WO2021030451A1

WO2021030451A1 - Glycerol as a permeation enhancer and compositions containing the same

Info

Publication number: WO2021030451A1
Application number: PCT/US2020/045953
Authority: WO
Inventors: Qi-Ying Hu; John Lee
Original assignee: Decibel Therapeutics, Inc
Priority date: 2019-08-14
Filing date: 2020-08-12
Publication date: 2021-02-18

Abstract

The invention provides auricular dosage forms containing glycerol as a permeation enhancer for therapeutic agent delivery to the inner ear via the round window membrane. Exemplary conditions that may be treated and/or prevented using the auricular dosage forms described herein are, without limitation, otic diseases, such as ceruminosis, ear pruritus, otitis externa, otalgia, tinnitus, vestibular dysfunction, ear fullness, Meniere's disease, auditory neuropathy, platinum-induced ototoxicity, and sensorineural hearing loss, among others.

Description

GLYCEROL AS A PERMEATION ENHANCER AND COMPOSITIONS CONTAINING THE SAME

FIELD OF THE INVENTION

The invention relates to the field of therapeutic treatment, such as of otic diseases and conditions in human patients.

BACKGROUND

The inner ear represents an environment in which a variety of important cells and tissue systems reside. Among the cells that are resident in this niche are sensory hair cells, which are specialized mechanosensory receptors found in vertebrate auditory, vestibular and lateral line organs that transduce vibratory and acoustic stimuli into the sensations of hearing and balance. Sensorineural hearing loss typically occurs when hair cells are damaged from infection, noise exposure, ototoxins, and age-related decline. Worldwide, 1 .3 billion humans suffer some form of hearing loss, while 360 million suffer debilitating hearing loss as a direct result of the absence of these sensory hair cells. Numerous well- known drugs are known to have ototoxic effects, including aminoglycoside antibiotics, cisplatin, loop diuretics, antimalarial sesquiterpene lactone endoperoxides, antimalarial quinines, salicylates, and interferon polypeptides. However, delivery therapeutic agents into the inner ear where they may exert a beneficial phenotype remains a challenge due to the difficulty associated with penetrating the epithelial barrier of the round window membrane. There exists a need for improved auricular dosage forms for delivery of therapeutic agents across the round window membrane.

SUMMARY OF THE INVENTION

The present disclosure relates to auricular dosage forms and methods for the otic delivery of therapeutic agents to subjects in need thereof, such as human subjects. Particularly, the auricular dosage forms and methods described herein can be used to effectuate the passage of therapeutic agents across the round window membrane of a subject into the inner ear, where the therapeutic agents may exert a beneficial effect. The auricular dosage forms and methods described herein solve a challenging biological problem, as the administration of therapeutic agents - particularly large substances, such as proteins, viral vectors, nucleic acids, and nanoparticles, among others - across the round window membrane has been a difficult barrier to overcome. The auricular dosage forms and methods described herein provide important clinical benefits, as these can be used not only to deliver therapeutic agents across the round window membrane and into the inner ear, but also sustain high, therapeutically effective concentrations of these agents in vivo for long periods of time.

In one aspect, the invention features an auricular dosage form including a therapeutic agent, a gelling agent, and a permeation enhancing amount of glycerol.

In some embodiments, the auricular dosage form is hypertonic. In certain embodiments, the calculated osmolarity of the auricular dosage form is 400-7,000 mOsm/L (e.g., 600-7,000 mOsm/L, 700- 7,000 mOsm/L, 800-7,000 mOsm/L, 900-7,000 mOsm/L, 1 ,000-7,000 mOsm/L, 1 ,500-7,000 mOsm/L, 2,000-7,000 mOsm/L, 2,500-7,000 mOsm/L, 3,000-7,000 mOsm/L, 600-6,000 mOsm/L, 700-6,000 mOsm/L, 800-6,000 mOsm/L, 900-6,000 mOsm/L, 1 ,000-6,000 mOsm/L, 1 ,500-6,000 mOsm/L, 2,000- 6,000 mOsm/L, 2,500-6,000 mOsm/L, 3,000-6,000 mOsm/L, 600-5,000 mOsm/L, 700-5,000 mOsm/L, 800-5,000 mOsm/L, 900-5,000 mOsm/L, 1 ,000-5,000 mOsm/L, 1 ,500-5,000 mOsm/L, 2,000-5,000 mOsm/L, 2,500-5,000 mOsm/L, 3,000-5,000 mOsm/L, 500-4,000 mOsm/L, 600-4,000 mOsm/L, 700- 4,000 mOsm/L, 800-4,000 mOsm/L, 900-4,000 mOsm/L, 1 ,000-4,000 mOsm/L, 1 ,500-4,000 mOsm/L, 2,000-4,000 mOsm/L, 2,500-4,000 mOsm/L, 3,000-4,000 mOsm/L, 500-3,000 mOsm/L, 600-3,000 mOsm/L, 700-3,000 mOsm/L, 800-3,000 mOsm/L, 900-3,000 mOsm/L, 1 ,000-3,000 mOsm/L, 1 ,500- 3,000 mOsm/L, 2,000-3,000 mOsm/L, 2,500-3,000 mOsm/L, 500-2,500 mOsm/L, 600-2,500 mOsm/L, 700-2,500 mOsm/L, 800-2,500 mOsm/L, 900-2,500 mOsm/L, 1 ,000-2,500 mOsm/L, 1 ,500-2,500 mOsm/L, 2,000-2,500 mOsm/L, 500-2,000 mOsm/L, 600-2,000 mOsm/L, 700-2,000 mOsm/L, 800-2,000 mOsm/L, 900-2,000 mOsm/L, 1 ,000-2,000 mOsm/L, 1 ,500-2,000 mOsm/L, 500-1 ,500 mOsm/L, 600- 1 ,500 mOsm/L, 700-1 ,500 mOsm/L, 800-1 ,500 mOsm/L, 900-1 ,500 mOsm/L, or 1 ,000-1 ,500 mOsm/L). Preferably, the calculated osmolarity of the auricular dosage form is 400-7,000 mOsm/L.

In other embodiments, the auricular dosage form includes at least 1% (w/v) (e.g., at least 5% (w/v), at least 10% (w/v), at least 15% (w/v), at least 20% (w/v), at least 25% (w/v), at least 30% (w/v), at least 35% (w/v), or at least 40% (w/v); e.g., 90% (w/v) or less, 80% (w/v) or less, 75% (w/v) or less, 70% (w/v) or less, 65% (w/v) or less, 60% (w/v) or less, 55% (w/v) or less, 50% (w/v) or less, 45% (w/v) or less, 40% (w/v) or less, or 30% (w/v) or less; e.g., 1% (w/v) to 90% (w/v), 5% (w/v) to 90% (w/v), 10% (w/v) to 90% (w/v), 15% (w/v) to 90% (w/v), 20% (w/v) to 90% (w/v), 25% (w/v) to 90% (w/v), 30% (w/v) to 90% (w/v), 35% (w/v) to 90% (w/v), 40% (w/v) to 90% (w/v), 1% (w/v) to 80% (w/v), 5% (w/v) to 80%

(w/v), 10% (w/v) to 80% (w/v), 15% (w/v) to 80% (w/v), 20% (w/v) to 80% (w/v), 25% (w/v) to 80% (w/v), 30% (w/v) to 80% (w/v), 35% (w/v) to 80% (w/v), 40% (w/v) to 80% (w/v), 1% (w/v) to 75% (w/v), 5% (w/v) to 75% (w/v), 10% (w/v) to 75% (w/v), 15% (w/v) to 75% (w/v), 20% (w/v) to 75% (w/v), 25% (w/v) to 75% (w/v), 30% (w/v) to 75% (w/v), 35% (w/v) to 75% (w/v), 40% (w/v) to 75% (w/v), 1 % (w/v) to 70% (w/v),

5% (w/v) to 70% (w/v), 10% (w/v) to 70% (w/v), 15% (w/v) to 70% (w/v), 20% (w/v) to 70% (w/v), 25% (w/v) to 70% (w/v), 30% (w/v) to 70% (w/v), 35% (w/v) to 70% (w/v), 40% (w/v) to 70% (w/v), 1% (w/v) to 65% (w/v), 5% (w/v) to 65% (w/v), 10% (w/v) to 65% (w/v), 15% (w/v) to 65% (w/v), 20% (w/v) to 65% (w/v), 25% (w/v) to 65% (w/v), 30% (w/v) to 65% (w/v), 35% (w/v) to 65% (w/v), 40% (w/v) to 65% (w/v),

1 % (w/v) to 60% (w/v), 5% (w/v) to 60% (w/v), 10% (w/v) to 60% (w/v), 15% (w/v) to 60% (w/v), 20% (w/v) to 60% (w/v), 25% (w/v) to 60% (w/v), 30% (w/v) to 60% (w/v), 35% (w/v) to 60% (w/v), 40% (w/v) to 60% (w/v), 1% (w/v) to 55% (w/v), 5% (w/v) to 55% (w/v), 10% (w/v) to 55% (w/v), 15% (w/v) to 55% (w/v),

20% (w/v) to 55% (w/v), 25% (w/v) to 55% (w/v), 30% (w/v) to 55% (w/v), 35% (w/v) to 55% (w/v), 40% (w/v) to 55% (w/v), 1% (w/v) to 50% (w/v), 5% (w/v) to 50% (w/v), 10% (w/v) to 50% (w/v), 15% (w/v) to 50% (w/v), 20% (w/v) to 50% (w/v), 25% (w/v) to 50% (w/v), 30% (w/v) to 50% (w/v), 35% (w/v) to 50% (w/v), 40% (w/v) to 50% (w/v), 1% (w/v) to 45% (w/v), 5% (w/v) to 45% (w/v), 10% (w/v) to 45% (w/v),

15% (w/v) to 45% (w/v), 20% (w/v) to 45% (w/v), 25% (w/v) to 45% (w/v), 30% (w/v) to 45% (w/v), 35% (w/v) to 45% (w/v), 40% (w/v) to 45% (w/v), 1% (w/v) to 40% (w/v), 5% (w/v) to 40% (w/v), 10% (w/v) to 40% (w/v), 15% (w/v) to 40% (w/v), 20% (w/v) to 40% (w/v), 25% (w/v) to 40% (w/v), 30% (w/v) to 40% (w/v), 35% (w/v) to 40% (w/v), 1% (w/v) to 35% (w/v), 5% (w/v) to 35% (w/v), 10% (w/v) to 35% (w/v),

15% (w/v) to 35% (w/v), 20% (w/v) to 35% (w/v), 25% (w/v) to 35% (w/v), 30% (w/v) to 35% (w/v), 1% (w/v) to 30% (w/v), 5% (w/v) to 30% (w/v), 10% (w/v) to 30% (w/v), 15% (w/v) to 30% (w/v), 20% (w/v) to 30% (w/v), 25% (w/v) to 30% (w/v), 1% (w/v) to 25% (w/v), 5% (w/v) to 25% (w/v), 10% (w/v) to 25%

(w/v), 15% (w/v) to 25% (w/v), or 20% (w/v) to 25% (w/v)) of glycerol.

In yet other embodiments, the gelling agent is hyaluronan, a polyoxyethylene-polyoxypropylene block copolymer, poly(lactic-co-glycolic) acid, polylactic acid, polycaprolactone, alginic acid or a salt thereof, polyethylene glycol, a cellulose, a cellulose ether, a carbomer, agar-agar, gelatin, glucomannan, galactomannan, xanthan gum, chitosan, pectin, starch, tragacanth, carrageenan, polyvinylpyrrolidone, polyvinyl alcohol, paraffin, petrolatum, silicates, fibroin, or a combination thereof. In still other embodiments, the auricular dosage form further contains a gelling agent. In some embodiments, the gelling agent is hyaluronan, hyaluronic acid, a polyoxyethylene-polyoxypropylene block copolymer, poly(lactic-co-glycolic) acid, polylactic acid, polycaprolactone, alginic acid or a salt thereof, polyethylene glycol, a cellulose, a cellulose ether, agar-agar, gelatin, glucomannan, galactomannan (e.g., locust bean gum or tara gum), xanthan gum, guar gum, chitosan, pectin, starch, tragacanth, carrageenan, polyvinylpyrrolidone, polyvinyl alcohol, paraffin, polyethoxylated sorbitan monolaurate, petrolatum, silicates, fibroin, gellan, CARBOPOL 940®, polyoxamines, lecithin gels, polysorbate-80, (poly)aniline derivatives, xyloglucane, collagen, silicon dioxide, tyloxapol, Cremophor, aluminum magnesium silicate, sodium stearate, bladderwrack, bentonite, eratonia, chondrus, dextrose, furcellaran, Ghatti gum, hectorite, lactose, sucrose, sucralose, maltodextrin, mannitol, sorbitol, honey, maize starch, wheat starch, rice starch, potato starch, oxypolygelatin, polygeline, sterculia gum, propylene carbonate, methyl vinyl ether/maleic anhydride copolymer, poly(methoxyethyl methacrylate), and poly(methoxyethoxyethyl methacrylate), and combinations thereof. In some embodiments, the gelling agent is a polyoxyethylene- polyoxypropylene block copolymer, alginic acid or a pharmaceutically acceptable salt thereof, collagen, hyaluronic acid or a pharmaceutically acceptable salt thereof, gelatin, or fibroin. In some embodiments, the polyoxyethylene-polyoxypropylene block copolymer is poloxamer 407. In some embodiments, the polyoxyethylene-polyoxypropylene block copolymer is poloxamer 188.

In some embodiments, the polyoxyethylene-polyoxypropylene block copolymer is present within the auricular dosage form at a concentration of from about 0.001% w/v to about 50% w/v. In some embodiments, the polyoxyethylene-polyoxypropylene block copolymer is present within the auricular dosage form at a concentration of from about 0.01% w/v to about 40% w/v. In some embodiments, the polyoxyethylene-polyoxypropylene block copolymer is present within the auricular dosage form at a concentration of from about 1% w/v to about 30% w/v. In some embodiments, the polyoxyethylene- polyoxypropylene block copolymer is present within the auricular dosage form at a concentration of about 20% w/v.

In further embodiments, the gelling agent is hyaluronan. In yet further embodiments, the gelling agent is a polyoxyethylene-polyoxypropylene block copolymer. In still further embodiments, the polyoxyethylene-polyoxypropylene block copolymer is poloxamer 407, poloxamer 188, or a combination thereof. In other embodiments, the gelling agent is a cellulose ether. In yet other embodiments, the cellulose ether is methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, methyl hydroxyethylcellulose, hydroxypropyl methylcellulose, hydroxypropylcellulose, or a combination thereof.

In still other embodiments, the gelling agent is fibroin. In some embodiments, the gelling agent is alginic acid or a salt thereof. In certain embodiments, the gelling agent is cross-linked. In particular embodiments, the gelling agent is ionically cross-linked. In further embodiments, the gelling agent is covalently cross-linked.

In yet further embodiments, the concentration of the therapeutic agent is at least 0.05M, at least 0.1 M, at least 0.2M, at least 0.3M, at least 0.4M, at least 0.5M, or at least 1 .0M; e.g., 2.5M or less, 2.0M or less, 1 .5M or less, 1 .0M or less, 0.5M or less, 0.4M or less, 0.3M or less, or 0.2M or less; e.g., 0.5M- 2.5M 0.05M to 1 .5 M, 0.05M to 0.5M, 0.05M to 0.2M, 0.05M to 0.1 M, 0.1 M to 1 5M, 0.1 M to 0.5M, 0.1 M to 0.2M, 0.2M to 1 5M, 0.2M to 0.5M, 0.5M to 1 5M, 0.05M to 1 .0 M, 0.05M to 0.5M, 0.05M to 0.2M, 0.05M to 0.1 M, 0.1 M to 1 0M, 0.1 M to 0.5M, 0.1 M to 0.2M, 0.2M to 1 0M, 0.2M to 0.5M, 0.5M to 1 0M, or 1 0M to 1.5M.

In still further embodiments, the auricular dosage form includes a pharmaceutically acceptable liquid solvent (e.g., water). In some embodiments, the pH of the dosage form is 6.5 to 8.5.

In certain embodiments, the auricular dosage form is an auricular unit dosage form. In particular embodiments, the auricular unit dosage form has a volume of at least 0.05 ml_ (e.g., at least 0.1 ml_, at least 0.2 ml_, at least 0.3 ml_, at least 0.4 ml_, at least 0.5 ml_, at least 0.6 ml_, at least 0.7 ml_, at least 0.8 ml_, at least 0.9 ml_, or at least 1 ml_; e.g., 1 .1 ml_ or less, 1 ml_ or less, 0.9 ml_ or less, 0.8 ml_ or less, 0.7 ml_ or less, 0.6 ml_ or less, 0.5 ml_ or less, 0.4 ml_ or less, 0.3 ml_ or less, or 0.2 ml_ or less; e.g., 0.05 ml_ to 1 .1 ml_, 0.1 ml_ to 1 .1 ml_, 0.2 ml_ to 1 .1 ml_, 0.3 ml_ to 1 .1 ml_, 0.4 ml_ to 1 .1 ml_, 0.5 ml_ to 1 .1 ml_, 0.6 ml_ to 1 .1 ml_, 0.7 ml_ to 1 .1 ml_, 0.8 ml_ to 1 .1 ml_, 0.9 ml_ to 1 .1 ml_, 1 ml_ to 1 .1 ml_, 0.05 ml_ to 1 ml_,

0.1 ml_ to 1 ml_, 0.2 ml_ to 1 ml_, 0.3 ml_ to 1 ml_, 0.4 ml_ to 1 ml_, 0.5 ml_ to 1 ml_, 0.6 ml_ to 1 mL, 0.7 ml_ to 1 mL, 0.8 mL to 1 mL, 0.9 mL to 1 mL, 0.05 mL to 0.9 mL, 0.1 mL to 0.9 mL, 0.2 mL to 0.9 mL, 0.3 mL to 0.9 mL, 0.4 mL to 0.9 mL, 0.5 mL to 0.9 mL, 0.6 mL to 0.9 mL, 0.7 mL to 0.9 mL, 0.8 mL to 0.9 mL,

0.05 mL to 0.8 mL, 0.1 mL to 0.8 mL, 0.2 mL to 0.8 mL, 0.3 mL to 0.8 mL, 0.4 mL to 0.8 mL, 0.5 mL to 0.8 mL, 0.6 mL to 0.8 mL, 0.7 mL to 0.8 mL, 0.05 mL to 0.7 mL, 0.1 mL to 0.7 mL, 0.2 mL to 0.7 mL, 0.3 mL to 0.7 mL, 0.4 mL to 0.7 mL, 0.5 mL to 0.7 mL, 0.6 mL to 0.7 mL, 0.05 mL to 0.6 mL, 0.1 mL to 0.6 mL,

0.2 mL to 0.6 mL, 0.3 mL to 0.6 mL, 0.4 mL to 0.6 mL, 0.5 mL to 0.6 mL, 0.05 mL to 0.5 mL, 0.1 mL to 0.5 mL, 0.2 mL to 0.5 mL, 0.3 mL to 0.5 mL, 0.4 mL to 0.5 mL, 0.05 mL to 0.4 mL, 0.1 mL to 0.4 mL, 0.2 mL to 0.4 mL, 0.3 mL to 0.4 mL, 0.05 mL to 0.3 mL, 0.1 mL to 0.3 mL, or 0.2 mL to 0.3 mL).

In some embodiments, upon administration (for example, upon intratympanic or transtympanic administration, such as intratympanic or transtympanic injection) to a mammalian subject, the therapeutic agent is delivered across the round window membrane of the subject. In some embodiments, upon administration (for example, upon intratympanic or transtympanic administration, such as intratympanic or transtympanic injection) to a mammalian subject, the therapeutic agent remains present within perilymph of the subject for at least from about 1 hour to about 6 weeks following the administration to the subject (e.g., at least 1 hour, about 12 hours, about 24 hours, about 1 week, about 2 weeks, about 3 weeks, about 4 weeks, about 5 weeks, about 6 weeks, or more). In some embodiments, upon administration (for example, upon intratympanic or transtympanic administration, such as intratympanic or transtympanic injection) to a mammalian subject, the therapeutic agent remains present within perilymph of the subject for at least from about 4 hours to about 6 weeks following the administration to the subject. In some embodiments, upon administration (for example, upon intratympanic or transtympanic administration, such as intratympanic or transtympanic injection) to a mammalian subject, the therapeutic agent remains present within perilymph of the subject for at least from about 8 hours to about 6 weeks following the administration to the subject. In some embodiments, upon administration (for example, upon intratympanic or transtympanic administration, such as intratympanic or transtympanic injection) to a mammalian subject, the therapeutic agent remains present within perilymph of the subject for at least from about 12 hours to about 6 weeks following the administration to the subject. In some embodiments, upon administration (for example, upon intratympanic or transtympanic administration, such as intratympanic or transtympanic injection) to a mammalian subject, the therapeutic agent remains present within perilymph of the subject for at least from about 24 hours to about 6 weeks following the administration to the subject. In some embodiments, upon administration (for example, upon intratympanic or transtympanic administration, such as intratympanic or transtympanic injection, such as intratympanic or transtympanic injection) to a mammalian subject, the therapeutic agent remains present within perilymph of the subject for at least from about 48 hours to about 6 weeks following the administration to the subject. In some embodiments, upon administration (for example, upon intratympanic or transtympanic administration, such as intratympanic or transtympanic injection) to a mammalian subject, the therapeutic agent remains present within perilymph of the subject for at least from about 72 hours to about 6 weeks following the administration to the subject. In some embodiments, upon administration (for example, upon intratympanic or transtympanic administration, such as intratympanic or transtympanic injection) to a mammalian subject, the therapeutic agent remains present within perilymph of the subject for at least from about 96 hours to about 6 weeks following the administration to the subject.

In some embodiments, the therapeutic agent is an anti-platinum chemoprotectant agent (e.g., an alkaline or ammonium thiosulfate salt or a solvate thereof, an alkaline diethyldithiocarbamate salt, amifostine, methionine, N-acetylcysteine, cysteine, 2-aminoethanethiol, glutathione (GSH) or a C1-C6 alkyl ester thereof, lysine, histidine, arginine, ethylene diamine tetraacetic acid, dimercaprol, dimercaptosuccinic acid, dimercapto-propane sulfonate salt, penicillamine, a-lipoic acid, or fursultiamine, or a salt thereof). In certain embodiments, the anti-platinum chemoprotectant agent is an alkaline thiosulfate salt, ammonium thiosulfate salt, or a solvate thereof. In particular embodiments, the alkaline thiosulfate salt is sodium thiosulfate or a solvate thereof. In further embodiments, the anti-platinum chemoprotectant agent is N-acetylcysteine or a salt thereof.

In some embodiments, the therapeutic agent is a neurotrophin, an immunomodulating agent, an aural pressure modulating agent, a corticosteroid, an antimicrobial agent, an antagonist of truncated TrkC or truncated TrkB, a non-natural TrkB or TrkC agonist, a TrkB receptor agonist antibody, a TrkB receptor agonist compound, a TrkC receptor agonist antibody, a TrkC receptor agonist compound, an Atohl modulator, a WNT modulator, or an anti-platinum chemoprotectant agent. In some embodiments, the therapeutic agent is a TrkB receptor agonist antibody. In some embodiments, the therapeutic agent is a TrkC receptor agonist antibody. In some embodiments, the therapeutic agent is a Wnt modulator. In some embodiments, the therapeutic agent is an Atohl modulator (e.g., an Atohl polypeptide or a nucleic acid vector engineered to express Atohl , e.g., human Atohl (Hathl )). In some embodiments, the therapeutic agent is an anti-platinum chemoprotectant agent.

In some embodiments, the therapeutic agent is a neurotrophin. In some embodiments, the neurotrophin is selected from neurotrophin-3 (NT-3), nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), a pan-neurotrophin (e.g., PNT-1) a chimeric neurotrophin, glial cell-line derived neurotrophic factor (GDNF), neurotrophin-4 (NT-4), fibroblast growth factor (FGF), insulin-like growth factor (IGF), epidermal growth factor (EGF), platelet-derived growth factor (PGF), mesencephalic astrocyte-derived neurotrophic factor (MANF), cerebral dopamine neurotrophic factor (CDNF), and combinations thereof.

In some embodiments, the neurotrophin is NT-3. In some embodiments, the NT-3 has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 1 . In some embodiments, the NT-3 has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 7. In some embodiments, the NT-3 has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the NT-3 has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 1 . In some embodiments, the NT-3 has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 7. In some embodiments, the NT-3 has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the NT-3 has an amino acid sequence having at least 95% (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 1 . In some embodiments, the NT-3 has an amino acid sequence having at least 95% (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 7. In some embodiments, the NT-3 has an amino acid sequence having at least 95% (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 8. In some embodiments, the NT-3 has an amino acid sequence that differs from the amino acid sequence of SEQ ID NO: 1 , SEQ ID NO: 7, or SEQ ID NO: 8 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. In some embodiments, the NT-3 is an NT-3 variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of SEQ ID NO: 1 , SEQ ID NO: 7, or SEQ ID NO: 8. In some embodiments, the NT-3 variant has the sequence of any one of SEQ ID NOs: 34-46. In some embodiments, the NT-3 variant has the sequence of SEQ ID NO: 35. In some embodiments, the NT-3 variant has the sequence of SEQ ID NO: 43. In some embodiments, the NT-3 variant has the sequence of SEQ ID NO: 44. In some embodiments, the NT-3 is an NT-3 variant having an amino acid sequence with one or more (e.g., 1 , 2,

3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of SEQ ID NO: 1 , SEQ ID NO: 7, or SEQ ID NO: 8 and/or one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) deleted amino acids relative to the amino acid sequence of SEQ ID NO: 1 , SEQ ID NO: 7, or SEQ ID NO: 8. In some embodiments, the NT-3 is encoded by a nucleic acid having the sequence of SEQ ID NO: 2 or SEQ ID NO: 56.

In some embodiments, the neurotrophin is NGF. In some embodiments, the NGF has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 5. In some embodiments, the NGF has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 6. In some embodiments, the NGF has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 5. In some embodiments, the NGF has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 6. In some embodiments, the NGF has an amino acid sequence having at least 95% (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 5. In some embodiments, the NGF has an amino acid sequence having at least 95% (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 6. In some embodiments, the NGF has an amino acid sequence that differs from the amino acid sequence of SEQ ID NO: 5 or SEQ ID NO:6 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. In some embodiments, the NGF is an NGF variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of SEQ ID NO: 5 or SEQ ID NO: 6. In some embodiments, the NGF variant has the sequence any one of SEQ ID NOs: 20-23. In some embodiments, the NGF is an NGF variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of SEQ ID NO: 5 or SEQ ID NO: 6 and/or one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) deleted amino acids relative to the amino acid sequence of SEQ ID NO: 5 or SEQ ID NO: 6. In some embodiments, the NGF variant has the sequence of SEQ ID NO: 24. In some embodiments, the NGF is encoded by a nucleic acid having the sequence of SEQ ID NO: 55 or SEQ ID NO: 62.

In some embodiments, the neurotrophin is NT-4. In some embodiments, the NT-4 has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 9. In some embodiments, the NT-4 has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 10. In some embodiments, the NT-4 has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 9. In some embodiments, the NT-4 has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 10. In some embodiments, the NT-4 has an amino acid sequence having at least 95% (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 9. In some embodiments, the NT-4 has an amino acid sequence having at least 95% (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 10. In some embodiments, the NT- 4 has an amino acid sequence that differs from the amino acid sequence of SEQ ID NO: 9 or SEQ ID NO:10 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. In some embodiments, the NT-4 is an NT-4 variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of SEQ ID NO: 9 or SEQ ID NO: 10. In some embodiments, the NT-4 is an NT-4 variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of SEQ ID NO: 9 or SEQ ID NO: 10 and/or one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) deleted amino acids relative to the amino acid sequence of SEQ ID NO: 9 or SEQ ID NO: 10. In some embodiments, the NT- 4 is encoded by a nucleic acid having the sequence of SEQ ID NO: 57.

In some embodiments, the neurotrophin is BDNF. In some embodiments, the BDNF has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 11. In some embodiments, the BDNF has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of any one of SEQ ID NOs: 12-15. In some embodiments, the BDNF has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 16. In some embodiments, the BDNF has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 11. In some embodiments, the BDNF has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of any one of SEQ ID NOs: 12-15. In some embodiments, the BDNF has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 16. In some embodiments, the BDNF has an amino acid sequence having at least 95% (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 11. In some embodiments, the BDNF has an amino acid sequence having at least 95% (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of any one of SEQ ID NOs: 12-15. In some embodiments, the BDNF has an amino acid sequence having at least 95% (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 16. In some embodiments, the BDNF has an amino acid sequence that differs from the amino acid sequence of any one of SEQ ID NOs: 11 -16 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. In some embodiments, the BDNF is a BDNF variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8,

9, 10 or more) amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOs: 11 -16. In some embodiments, the BDNF is a BDNF variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOs: 11 -16 and/or one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) deleted amino acids relative to the amino acid sequence of any one of SEQ ID NOs: 11 -16. In some embodiments, the BDNF is encoded by a nucleic acid having the sequence of any one of SEQ ID NOs: 58-61.

In some embodiments, the neurotrophin is a pan-neurotrophin. In some embodiments, the pan- neurotrophin is PNT-1 . In some embodiments, the PNT-1 has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 17. In some embodiments, the PNT-1 has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 17. In some embodiments, the PNT-1 has an amino acid sequence having at least 95% (e.g., at least 95%, 96%, 97%, 98%, 99%,

99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 17. In some embodiments, the PNT-1 has an amino acid sequence that differs from the amino acid sequence of SEQ ID NO: 17 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. In some embodiments, the PNT-1 is a PNT-1 variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of SEQ ID NO: 17. In some embodiments, the PNT-1 variant has the sequence any one of SEQ ID NOs: 25-28 or 31 -33. In some embodiments, the PNT-1 is a PNT-1 variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9,

10 or more) amino acid substitutions relative to the amino acid sequence of SEQ ID NO: 17 and/or one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) deleted amino acids relative to the amino acid sequence of SEQ ID NO: 17.

In some embodiments, the neurotrophin is a chimeric neurotrophin. In some embodiments, the chimeric neurotrophin is an NGF/BDNF chimera. In some embodiments, the chimeric neurotrophin has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 18. In some embodiments, the chimeric neurotrophin has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 19. In some embodiments, the chimeric neurotrophin has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 29. In some embodiments, the chimeric neurotrophin has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 30. In some embodiments, the chimeric neurotrophin has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 18. In some embodiments, the chimeric neurotrophin has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 19. In some embodiments, the chimeric neurotrophin has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 29. In some embodiments, the chimeric neurotrophin has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%,

91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 30. In some embodiments, the chimeric neurotrophin has an amino acid sequence having at least 95% (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 18. In some embodiments, the chimeric neurotrophin has an amino acid sequence having at least 95% (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 19. In some embodiments, the chimeric neurotrophin has an amino acid sequence having at least 95% (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 29. In some embodiments, the chimeric neurotrophin has an amino acid sequence having at least 95% (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 30. In some embodiments, the chimeric neurotrophin has an amino acid sequence that differs from the amino acid sequence of any one of SEQ ID NOs: 18, 19, 29, or 30 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. In some embodiments, the chimeric neurotrophin is a chimeric neurotrophin variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOs:

18, 19, 29, or 30. In some embodiments, the chimeric neurotrophin is a chimeric neurotrophin variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOs: 18, 19, 29, or 30 and/or one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) deleted amino acids relative to the amino acid sequence of any one of SEQ ID NOs: 18, 19, 29, or 30.

In some embodiments, the neurotrophin is CNTF. In some embodiments, the CNTF has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 47. In some embodiments, the CNTF has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 47. In some embodiments, the CNTF has an amino acid sequence having at least 95% (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 47. In some embodiments, the CNTF has an amino acid sequence that differs from the amino acid sequence of SEQ ID NO: 47 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. In some embodiments, the CNTF is a CNTF variant having an amino acid sequence with one or more (e.g., 1 , 2,

3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of SEQ ID NO: 47. In some embodiments, the CNTF is a CNTF variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of SEQ ID NO: 47 and/or one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) deleted amino acids relative to the amino acid sequence of SEQ ID NO: 47. In some embodiments, the CNTF is encoded by a nucleic acid having the sequence of SEQ ID NO: 63.

In some embodiments, the neurotrophin is IGF (e.g., IGF1 or IGF2). In some embodiments, the IGF is IGF1 and has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 48. In some embodiments, the IGF is IGF1 and has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 49. In some embodiments, the IGF is IGF1 and has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 50 or SEQ ID NO: 51 . In some embodiments, the IGF is IGF2 and has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 52. In some embodiments, the IGF is IGF2 and has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 53. In some embodiments, the IGF is IGF2 and has an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the IGF is IGF1 and has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 48. In some embodiments, the IGF is IGF1 and has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 49. In some embodiments, the IGF is IGF1 and has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 50 or SEQ ID NO: 65. In some embodiments, the IGF is IGF2 and has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91 %, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 52. In some embodiments, the IGF is IGF2 and has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 53. In some embodiments, the IGF is IGF2 and has an amino acid sequence having at least 90% sequence identity (e.g., at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the IGF is IGF1 and has an amino acid sequence having at least 95% sequence identity (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 48. In some embodiments, the IGF is IGF1 and has an amino acid sequence having at least 95% sequence identity (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 49. In some embodiments, the IGF is IGF1 and has an amino acid sequence having at least 95% sequence identity (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 50 or SEQ ID NO: 51 . In some embodiments, the IGF is IGF2 and has an amino acid sequence having at least 95% sequence identity (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 52. In some embodiments, the IGF is IGF2 and has an amino acid sequence having at least 95% sequence identity (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 53. In some embodiments, the IGF is IGF2 and has an amino acid sequence having at least 95% sequence identity (e.g., at least 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 54. In some embodiments, the IGF is IGF1 and has an amino acid sequence that differs from the amino acid sequence of any one of SEQ ID NOs: 48-51 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. In some embodiments, the IGF is IGF2 and has an amino acid sequence that differs from the amino acid sequence of any one of SEQ ID NOs: 52-54 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. In some embodiments, the IGF is an IGF1 variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOs: 48-51 . In some embodiments, the IGF is an IGF2 variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOs: 52-54. In some embodiments, the IGF is an IGF1 variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOs: 48-51 and/or one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) deleted amino acids relative to the amino acid sequence of any one of SEQ ID NOs: 48-51 . In some embodiments, the IGF is an IGF2 variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOs: 52-54 and/or one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) deleted amino acids relative to the amino acid sequence of any one of SEQ ID NOs: 52-54. In some embodiments, the IGF is IGF1 and is encoded by a nucleic acid having the sequence of any one of SEQ ID NOs: 64-66. In some embodiments, the IGF is IGF1 and is encoded by a nucleic acid having the sequence of SEQ ID NO: 67 or SEQ ID NO: 68.

In some embodiments, the therapeutic agent is an anti-platinum chemoprotectant agent. In some embodiments, the anti-platinum chemoprotectant agent is an alkaline or ammonium thiosulfate salt or a solvate thereof, an alkaline diethyldithiocarbamate salt, amifostine, methionine, N-acetylcysteine, cysteine, 2-aminoethanethiol, glutathione (GSH) or a C1-C6 alkyl ester thereof, lysine, histidine, arginine, ethylene diamine tetraacetic acid, dimercaprol, dimercaptosuccinic acid, dimercapto-propane sulfonate salt, penicillamine, a-lipoic acid, or fursultiamine, or a salt thereof. In some embodiments, the anti platinum chemoprotectant agent is an alkaline thiosulfate salt, ammonium thiosulfate salt, or a solvate thereof. In some embodiments, wherein the alkaline thiosulfate salt is sodium thiosulfate or a solvate thereof. In some embodiments, the anti-platinum chemoprotectant agent is N-acetylcysteine or a salt thereof.

In some embodiments, the therapeutic agent is a glial cell line-derived neurotrophic factor family ligand, a neuropoietic cytokine, an anti-inflammatory cytokine, a neuroprotection agent, growth differentiation factor 11 , erythropoietin (EPO), granulocyte-colony stimulating factor, granulocyte- macrophage colony stimulating factor, growth differentiation factor-9, thrombopoietin, transforming growth factor alpha (TGF-a), stromal cell-derived factor 1 , myostatin (growth differentiation factor 8), parathyroid hormone, parathyroid hormone related peptide, interleukin 1 receptor antagonist, fibroblast growth factor 18, high-mobility group protein 2, glucocorticoid receptor, fibroblast growth factor 9, hepatocyte growth factor, or a TGFp-superfamily protein. In some embodiments, the therapeutic agent is a glial cell line-derived neurotrophic factor family ligand selected from glial cell line-derived neurotrophic factor (GDNF), neurturin, artemin, and persephin.

In some embodiments, the therapeutic agent is a neuropoietic cytokine selected from interleukin- 6, interleukin-11 , inteleukin-27, leukemia inhibitory factor, cardiotrophin 1 , neuropoietin, cardiotrophin-like cytokine, and fibroblast growth factor 2.

In some embodiments, the therapeutic agent is an anti-inflammatory cytokine selected from interleukin-4 and interleukin-10.

In some embodiments, the therapeutic agent is a neuroprotection agent selected from neuregulin-1 and vascular endothelial growth factor (VEGF).

In some embodiments, the therapeutic agent is a TGFp-superfamily protein selected from TGFp, TGFp3, BMP2, and BMP7.

In some embodiments, the therapeutic agent is a nucleic acid vector. In some embodiments, the nucleic acid vector is a plasmid, cosmid, artificial chromosome, or viral vector. In some embodiments, the viral vector is an adeno-associated virus (AAV), adenovirus, lentivirus, retrovirus, poxvirus, baculovirus, herpes simplex virus, or a vaccinia virus. In some embodiments, the viral vector is an AAV vector. In some embodiments, the serotype of the AAV vector is selected from the group consisting of AAV1 , AAV2, AAV3, AAV4, AAV5, AAV6, AAV7, AAV8, AAV9, AAV10, rh10, rh39, rh43, rh74, Anc80, Anc80L65, DJ/8, DJ/9, 7m8, PHP.B, PHP.eb, and PHP.S. In some embodiments, the serotype of the AAV vector is AAV1 . In some embodiments, the serotype of the AAV vector isAAV2. In some embodiments, the serotype of the AAV vector is 7m8. In some embodiments, the AAV vector has a mutation at one or more surface- exposed tyrosine residues on capsid proteins, such as Tyr252 to Phe272 (Y252F), Tyr272 to Phe272 (Y272F), Tyr444 to Phe444 (Y444F), Tyr500 to Phe500 (Y500F), Tyr700 to Phe700 (Y700F), Tyr704 to Phe704 (Y704F), Tyr730 to Phe730 (Y730F), and Tyr 733 to Phe733 (Y733F). In some embodiments, the nucleic acid vector (e.g., AAV vector) is engineered to express a protein described herein (e.g., a neurotrophin, such as NT-3, NGF, NT-4, BDNF, CNTF, IGF, PNT-1 , or a chimeric neurotrophin, or Atohl ). In some embodiments, the nucleic acid vector includes the sequence of any one of SEQ ID NOs: 2 or 55-68.

In some embodiments, the therapeutic agent is an antibody or antigen-binding fragment thereof. The antibody or antigen-binding fragment thereof may be, for example, a monoclonal antibody or antigen binding fragment thereof, a polyclonal antibody or antigen-binding fragment thereof, a humanized antibody or antigen-binding fragment thereof, a bispecific antibody or antigen-binding fragment thereof, a dual-variable immunoglobulin domain, a single-chain Fv molecule (scFv), a diabody, a triabody, a nanobody, an antibody-like protein scaffold, a Fv fragment, a Fab fragment, a F(ab’)2 molecule, or a tandem di-scFv.

In some embodiments, the therapeutic agent is a liposome, vesicle, synthetic vesicle, exosome, synthetic exosome, dendrimer, or nanoparticle.

In some embodiments, the therapeutic agent is a small molecule, such as a small molecule that is not naturally round window membrane-penetrant.

In some embodiments, the therapeutic agent is an interfering RNA, such as a short interfering RNA (siRNA), a short hairpin RNA (shRNA), or a micro RNA (miRNA).

In some embodiments, the auricular dosage form is a gel at normal human body temperature. In some embodiments, the gel has a dynamic viscosity of at about 100 cP to about 1 ,000,000 cP, such as a dynamic viscosity of about 100 cP, 200 cP, 300 cP, 400 cP, 500 cP, 600 cP, 700 cP, 800 cP, 900 cP, 1 ,000 cP, 2,000 cP, 3,000 cP, 4,000 cP, 5,000 cP, 6,000 cP, 7,000 cP, 8,000 cP, 9,000 cP, 10,000 cP, 20,000 cP, 30,000 cP, 40,000 cP, 50,000 cP, 60,000 cP, 70,000 cP, 80,000 cP, 90,000 cP, 100,000 cP, 200,000 cP, 300,000 cP, 400,000 cP, 500,000 cP, 600,000 cP, 700,000 cP, 800,000 cP, 900,000 cP, or 1 ,000,000 cP.

In some embodiments, the auricular dosage form further contains a pharmaceutically acceptable liquid solvent, such as water.

In some embodiments, the auricular dosage form contains one or more agents selected from an antimicrobial agent, an arylcycloalkylamine, an elipticine derivative, an anti-apoptotic agent, a c-JNK inhibitor, an antioxidant, an NSAID, an analgesic, a neuroprotection agent, a glutamate modulator, an interleukin 1 modulator, an interleukin-1 antagonist, a corticosteroid, an anti-TNF agent, a calcineurin inhibitor, an IKK inhibitor, an interleukin inhibitor, a platelet activating factor antagonist, a TNF-a converting enzyme (TACE) inhibitor, a Toll-like receptor inhibitor, an autoimmune agent, an IL-1 modulator, an RNA interference agent, an aquaporin modulator, an estrogen-related receptor beta modulator, a GAP junction protein, a vasopressin receptor modulator, a NMDA receptor modulator, an ENaC receptor modulator, an osmotic diuretic, a progesterone receptor, a prostaglandin, a cytotoxic agent, a cytoprotective agent, anti-intercellular adhesion molecule-1 antibody, an Atohl modulator (e.g., an Atohl polypeptide or a nucleic acid vector engineered to express Atohl , e.g., human Atohl (Hathl )), a Mathl modulator, a BFtN-3 modulator, a carbamate, an estrogen receptor, a fatty acid, a gamma- secretase inhibitor, a glutamate-receptor modulator, a neurotrophic agent, salicylic acid, nicotine, a retinoblastoma protein modulator, an ion channel blocker, a thyroid hormone receptor modulator, a TRPV modulator, an adenosine modulator, a KCNQ modulator, a P2X modulator, a CNS modulating agent, an anticholinergic, an antihistamine, a GABA receptor modulator, a neurotransmitter reuptake inhibitor, a thyrotropin-releasing hormone, a free radical modulator, a metal atom chelator, a mitochondrial modulator, a nitric oxide synthase modulator, a sirtuin modulator, a purinergic receptor modulator, a truncated TrkC or TrkB antagonist, a truncated TrkC or TrkB isoform, a nucleic acid polymer antagonist, a small molecule antagonist, a polypeptide antagonist, a non-natural TrkC or TrkB agonist, a neurotrophin variant, a WNT modulator, an anti-platinum chemoprotectant agent, a glycogen synthase kinase 3 (GSK3) inhibitor (e.g., a GSK3p and/or GSK3a inhibitor), a protein kinase C beta modulator, a repulsive guidance molecule a (RGMa) inhibitor, a neogenin inhibitor, a SK2 channel activator, a BK channel activator, a sphingosine-1 -phosphate receptor modulator, a sternness driver, a differentiation inhibitor, an N-Methyl-D-Aspartate (NMDA) receptor antagonist, a histone deacetylase (FIDAC) inhibitor, a proteasome inhibitor, an EZFI2/FIMT inhibitor, a notch inhibitor, ebselen, ancrod, an a-amino-3-hydroxy-5- methyl-4-isoxazolepropionic acid (AMPA) glutamate-positive allosteric modulator, D-methionine, an antagonist of histamine type 4 receptors, a chemotherapeutic accumulation reducer, choline ester, plant alkaloid, reversible cholinesterase inhibitor, acetylcholine release promoter, anti-adrenergic agent, a sympathomimetic agent, an antineoplastic agent , R(+)-N-propargyl-1 -aminoindan, and R-azasetron besylate. In some embodiments, the auricular dosage form further includes one or more agents selected from the group consisting of an antimicrobial agent, an anti-apoptotic agent, a c-JNK inhibitor, an antioxidant, an NSAID, an analgesic, a neuroprotection agent, a glutamate modulator, an interleukin 1 modulator, an interleukin-1 antagonist, a corticosteroid, an anti-TNF agent, a calcineurin inhibitor, an IKK inhibitor, an interleukin inhibitor, a platelet activating factor antagonist, a TNF-a converting enzyme (TACE) inhibitor, a Toll-like receptor inhibitor, an IL-1 modulator, an RNA interference agent, an aquaporin modulator, an estrogen-related receptor beta modulator, a GAP junction protein, a vasopressin receptor modulator, an NMDA receptor modulator, an ENaC receptor modulator, an osmotic diuretic, a progesterone receptor, a prostaglandin, a cytotoxic agent, a cytoprotective agent, an anti-intercellular adhesion molecule-1 antibody, an Atohl modulator, a Mathl modulator, a BRN-3 modulator, a carbamate, an estrogen receptor, a fatty acid, a gamma-secretase inhibitor, a glutamate-receptor modulator, a neurotrophic agent, salicylic acid, nicotine, a retinoblastoma protein modulator, an ion channel blocker, a thyroid hormone receptor modulator, a TRPV modulator, an adenosine modulator, a KCNQ modulator, a P2X modulator, a CNS modulating agent, an anticholinergic, an antihistamine, a GABA receptor modulator, a neurotransmitter reuptake inhibitor, a thyrotropin-releasing hormone, a free radical modulator, a metal atom chelator, a mitochondrial modulator, a nitric oxide synthase modulator, a sirtuin modulator, a purinergic receptor modulator, a truncated TrkC or TrkB antagonist, a truncated TrkC or TrkB isoform, a non-natural TrkC or TrkB agonist, a neurotrophin variant, a WNT modulator, anti platinum chemoprotectant agent, a glycogen synthase kinase inhibitor, a protein kinase C beta modulator, a repulsive guidance molecule a (RGMa) inhibitor, a neogenin inhibitor, a SK2 channel activator, a BK channel activator, a sphingosine-1 -phosphate receptor modulator, an N-Methyl-D-Aspartate (NMDA) receptor antagonist, a histone deacetylase (HDAC) inhibitor, a proteasome inhibitor, an EZH2/HMT inhibitor, a notch inhibitor, ebselen, ancrod, an a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate-positive allosteric modulator, D-methionine, an antagonist of histamine type 4 receptors, reversible cholinesterase inhibitor, acetylcholine release promoter, anti-adrenergic agent, a sympathomimetic agent, an antineoplastic agent, R(+)-N-propargyl-1-aminoindan, and R-azasetron besylate.

In another aspect, the invention features a method of delivering a therapeutic agent across the round window membrane of a subject (e.g., a mammalian subject, such as a human subject) by providing to the subject (e.g., by way of direct administration to the subject) a therapeutically effective amount of the auricular dosage form of any of the above aspects or embodiments of the invention. In some embodiments, the auricular dosage form is administered to or near the round window membrane. In some embodiments, the auricular dosage form is administered intratympanically or transtympanically. In some embodiments, the method is used to treat an otic disease, such as ceruminosis or ceruminosis associated with an otic disease or condition, ear pruritus, otitis externa, otalgia, tinnitus, vestibular dysfunction (e.g., vertigo, dizziness, or loss of balance), ear fullness, hearing loss, Meniere's disease, sensorineural hearing loss (e.g., noise-induced hearing loss, age-related hearing loss (presbycusis), ototoxic drug-induced hearing loss, hearing loss related to head trauma, hearing loss related to infection), autoimmune ear disease, ototoxicity, excitotoxicity, hidden hearing loss, cochlear synaptopathy, endolymphatic hydrops, labyrinthitis, Ramsay Hunt's Syndrome, vestibular neuronitis, or microvascular compression syndrome, hyperacusis, presbystasis, central auditory processing disorder, auditory neuropathy, improvement of cochlea implant performance, or a combination thereof.

In another aspect, the invention features a method of treating a subject (e.g., a mammalian subject, such as a human subject) having or at risk of developing hearing loss (e.g., sensorineural hearing loss, deafness, or auditory neuropathy) by administering to the subject a therapeutically effective amount of the auricular dosage form of any of the above aspects or embodiments of the invention, such as embodiments in which the therapeutic agent is a neurotrophin, an immunomodulating agent, an aural pressure modulating agent, a corticosteroid, an antimicrobial agent, an antagonist of truncated TrkC or truncated TrkB, a non-natural TrkB or TrkC agonist, a TrkB receptor agonist antibody, a TrkB receptor agonist compound, a TrkC receptor agonist antibody, a TrkC receptor agonist compound, an Atohl modulator, a neuroprotection agent, WNT modulator, or an anti-platinum chemoprotectant agent (e.g., embodiments in which the therapeutic agent is a neurotrophin selected from NT-3, NGF, BDNF, CNTF, GDNF, NT-4, FGF, IGF, EGF, PGF, MANF, CDNF, a pan-neurotrophin (e.g., PNT-1), a chimeric neurotrophin (e.g., a NGF/BDNF chimera), and combinations thereof, or embodiments in which the therapeutic agent is an anti-platinum chemoprotectant agent such as sodium thiosulfate or N- acetylcysteine).

In some embodiments of any of the above aspects, the hearing loss is genetic hearing loss. In some embodiments, the genetic hearing loss is autosomal dominant hearing loss, autosomal recessive hearing loss, or X-linked hearing loss.

In some embodiments of any of the above aspects, the hearing loss is acquired hearing loss. In some embodiments, the acquired hearing loss is noise-induced hearing loss, age-related hearing loss, disease or infection-related hearing loss, head trauma-related hearing loss, or ototoxic drug-induced hearing loss.

In another aspect, the invention features a method of treating a subject (e.g., a mammalian subject, such as a human subject) having or at risk of developing vestibular dysfunction by administering to the subject a therapeutically effective amount of the auricular dosage form of any of the above aspects or embodiments of the invention, such as embodiments in which the therapeutic agent is a neurotrophin, an immunomodulating agent, an aural pressure modulating agent, a corticosteroid, an antimicrobial agent, an antagonist of truncated TrkC or truncated TrkB, a non-natural TrkB or TrkC agonist, a TrkB receptor agonist antibody, a TrkB receptor agonist compound, a TrkC receptor agonist antibody, a TrkC receptor agonist compound, an Atohl modulator, a neuroprotection agent, WNT modulator, or an anti platinum chemoprotectant agent (e.g., embodiments in which the therapeutic agent is a neurotrophin selected from NT-3, NGF, BDNF, CNTF, GDNF, NT-4, FGF, IGF, EGF, PGF, MANF, CDNF, a pan- neurotrophin (e.g., PNT-1), a chimeric neurotrophin (e.g., a NGF/BDNF chimera), and combinations thereof, or embodiments in which the therapeutic agent is an anti-platinum chemoprotectant agent such as sodium thiosulfate or N-acetylcysteine).

In some embodiments of any of the above aspects, the vestibular dysfunction is vertigo, dizziness, or loss of balance.

In another aspect, the invention features a method of promoting hair cell regeneration in a subject (e.g., a mammalian subject, such as a human subject) in need thereof by administering to the subject a therapeutically effective amount of the auricular dosage form of any of the above aspects or embodiments of the invention, such as embodiments in which the therapeutic agent is a neurotrophin, an immunomodulating agent, an aural pressure modulating agent, a corticosteroid, an antimicrobial agent, an antagonist of truncated TrkC or truncated TrkB, a non-natural TrkB or TrkC agonist, a TrkB receptor agonist antibody, a TrkB receptor agonist compound, a TrkC receptor agonist antibody, a TrkC receptor agonist compound, an Atohl modulator, a neuroprotection agent, WNT modulator, or an anti-platinum chemoprotectant agent (e.g., embodiments in which the therapeutic agent is a neurotrophin selected from NT-3, NGF, BDNF, CNTF, GDNF, NT-4, FGF, IGF, EGF, PGF, MANF, CDNF, a pan-neurotrophin (e.g., PNT-1 ), a chimeric neurotrophin (e.g., a NGF/BDNF chimera), and combinations thereof).

In another aspect, the invention features a method of promoting SGN regeneration in a subject (e.g., a mammalian subject, such as a human subject) in need thereof by administering to the subject a therapeutically effective amount of the auricular dosage form of any of the above aspects or embodiments of the invention, such as embodiments in which the therapeutic agent is a neurotrophin, an immunomodulating agent, an aural pressure modulating agent, a corticosteroid, an antimicrobial agent, an antagonist of truncated TrkC or truncated TrkB, a non-natural TrkB or TrkC agonist, a TrkB receptor agonist antibody, a TrkB receptor agonist compound, a TrkC receptor agonist antibody, a TrkC receptor agonist compound, an Atohl modulator, a neuroprotection agent, WNT modulator, or an anti-platinum chemoprotectant agent (e.g., embodiments in which the therapeutic agent is a neurotrophin selected from NT-3, NGF, BDNF, CNTF, GDNF, NT-4, FGF, IGF, EGF, PGF, MANF, CDNF, a pan-neurotrophin (e.g., PNT-1 ), a chimeric neurotrophin (e.g., a NGF/BDNF chimera), and combinations thereof).

In another aspect, the invention features a method of preventing or reducing ototoxic drug- induced hair cell damage or death in a subject (e.g., a mammalian subject, such as a human subject) in need thereof by administering to the subject a therapeutically effective amount of the auricular dosage form of any of the above aspects or embodiments of the invention, such as embodiments in which the therapeutic agent is a neurotrophin, an immunomodulating agent, an aural pressure modulating agent, a corticosteroid, an antimicrobial agent, an antagonist of truncated TrkC or truncated TrkB, a non-natural TrkB or TrkC agonist, a TrkB receptor agonist antibody, a TrkB receptor agonist compound, a TrkC receptor agonist antibody, a TrkC receptor agonist compound, an Atohl modulator, a neuroprotection agent, WNT modulator, or an anti-platinum chemoprotectant agent (e.g., embodiments in which the therapeutic agent is a neurotrophin selected from NT-3, NGF, BDNF, CNTF, GDNF, NT-4, FGF, IGF, EGF, PGF, MANF, CDNF, a pan-neurotrophin (e.g., PNT-1 ), a chimeric neurotrophin (e.g., a NGF/BDNF chimera), and combinations thereof, or embodiments in which the therapeutic agent is an anti-platinum chemoprotectant agent such as sodium thiosulfate or N-acetylcysteine).

In another aspect, the invention features a method of preventing or reducing ototoxic drug- induced SGN damage or death in a subject (e.g., a mammalian subject, such as a human subject) in need thereof by administering to the subject a therapeutically effective amount of the auricular dosage form of any of the above aspects or embodiments of the invention, such as embodiments in which the therapeutic agent is a neurotrophin, an immunomodulating agent, an aural pressure modulating agent, a corticosteroid, an antimicrobial agent, an antagonist of truncated TrkC or truncated TrkB, a non-natural TrkB or TrkC agonist, a TrkB receptor agonist antibody, a TrkB receptor agonist compound, a TrkC receptor agonist antibody, a TrkC receptor agonist compound, an Atohl modulator, a neuroprotection agent, WNT modulator, or an anti-platinum chemoprotectant agent (e.g., embodiments in which the therapeutic agent is a neurotrophin selected from NT-3, NGF, BDNF, CNTF, GDNF, NT-4, FGF, IGF, EGF, PGF, MANF, CDNF, a pan-neurotrophin (e.g., PNT-1 ), a chimeric neurotrophin (e.g., a NGF/BDNF chimera), and combinations thereof, or embodiments in which the therapeutic agent is an anti-platinum chemoprotectant agent such as sodium thiosulfate or N-acetylcysteine).

In some embodiments of any of the above aspects, the ototoxic drug is selected from the group including aminoglycosides (e.g., gentamycin, neomycin, streptomycin, tobramycin, kanamycin, vancomycin, and amikacin), antineoplastic drugs (e.g., platinum-containing chemotherapeutic agents, such as cisplatin, carboplatin, and oxaliplatin), ethacrynic acid, furosemide, salicylates (e.g., aspirin, particularly at high doses), and quinine.

In another aspect, the invention features a method of preventing or mitigating platinum-induced ototoxicity in a subject by administering to the subject a therapeutically effective amount of the auricular dosage form of any of the above aspects or embodiments of the invention, such as embodiments in which the therapeutic agent is a neurotrophin, an immunomodulating agent, an aural pressure modulating agent, a corticosteroid, an antimicrobial agent, an antagonist of truncated TrkC or truncated TrkB, a non natural TrkB or TrkC agonist, a TrkB receptor agonist antibody, a TrkB receptor agonist compound, a TrkC receptor agonist antibody, a TrkC receptor agonist compound, an Atohl modulator, a neuroprotection agent, WNT modulator, or an anti-platinum chemoprotectant agent (e.g., embodiments in which the therapeutic agent is a neurotrophin selected from NT-3, NGF, BDNF, CNTF, GDNF, NT-4,

FGF, IGF, EGF, PGF, MANF, CDNF, a pan-neurotrophin (e.g., PNT-1 ), a chimeric neurotrophin (e.g., a NGF/BDNF chimera), and combinations thereof, or embodiments in which the therapeutic agent is an anti-platinum chemoprotectant agent such as sodium thiosulfate or N-acetylcysteine).

In another aspect, the invention features a method of treating a subject (e.g., a mammalian subject, such as a human subject) having or at risk of developing tinnitus by administering to the subject a therapeutically effective amount of the auricular dosage form of any of the above aspects or embodiments of the invention, such as embodiments in which the therapeutic agent is a neurotrophin, an immunomodulating agent, an aural pressure modulating agent, a corticosteroid, an antimicrobial agent, an antagonist of truncated TrkC or truncated TrkB, a non-natural TrkB or TrkC agonist, a TrkB receptor agonist antibody, a TrkB receptor agonist compound, a TrkC receptor agonist antibody, a TrkC receptor agonist compound, an Atohl modulator, a neuroprotection agent, WNT modulator, or an anti-platinum chemoprotectant agent (e.g., embodiments in which the therapeutic agent is a neurotrophin selected from NT-3, NGF, BDNF, CNTF, GDNF, NT-4, FGF, IGF, EGF, PGF, MANF, CDNF, a pan-neurotrophin (e.g., PNT-1 ), a chimeric neurotrophin (e.g., a NGF/BDNF chimera), and combinations thereof, or embodiments in which the therapeutic agent is an anti-platinum chemoprotectant agent such as sodium thiosulfate or N- acetylcysteine).

In another aspect, the invention features a method of preventing or reducing hair cell damage or death in a subject (e.g., a mammalian subject, such as a human subject) in need thereof by administering to the subject a therapeutically effective amount of the auricular dosage form of any of the above aspects or embodiments of the invention, such as embodiments in which the therapeutic agent is a neurotrophin, an immunomodulating agent, an aural pressure modulating agent, a corticosteroid, an antimicrobial agent, an antagonist of truncated TrkC or truncated TrkB, a non-natural TrkB or TrkC agonist, a TrkB receptor agonist antibody, a TrkB receptor agonist compound, a TrkC receptor agonist antibody, a TrkC receptor agonist compound, an Atohl modulator, a neuroprotection agent, WNT modulator, or an anti platinum chemoprotectant agent (e.g., embodiments in which the therapeutic agent is a neurotrophin selected from NT-3, NGF, BDNF, CNTF, GDNF, NT-4, FGF, IGF, EGF, PGF, MANF, CDNF, a pan- neurotrophin (e.g., PNT-1), a chimeric neurotrophin (e.g., a NGF/BDNF chimera), and combinations thereof, or embodiments in which the therapeutic agent is an anti-platinum chemoprotectant agent such as sodium thiosulfate or N-acetylcysteine).

In another aspect, the invention features a method of preventing or reducing SGN damage or death in a subject (e.g., a mammalian subject, such as a human subject) in need thereof by administering to the subject a therapeutically effective amount of the auricular dosage form of any of the above aspects or embodiments of the invention, such as embodiments in which the therapeutic agent is a neurotrophin, an immunomodulating agent, an aural pressure modulating agent, a corticosteroid, an antimicrobial agent, an antagonist of truncated TrkC or truncated TrkB, a non-natural TrkB or TrkC agonist, a TrkB receptor agonist antibody, a TrkB receptor agonist compound, a TrkC receptor agonist antibody, a TrkC receptor agonist compound, an Atohl modulator, a neuroprotection agent, WNT modulator, or an anti platinum chemoprotectant agent (e.g., embodiments in which the therapeutic agent is a neurotrophin selected from NT-3, NGF, BDNF, CNTF, GDNF, NT-4, FGF, IGF, EGF, PGF, MANF, CDNF, a pan- neurotrophin (e.g., PNT-1), a chimeric neurotrophin (e.g., a NGF/BDNF chimera), and combinations thereof, or embodiments in which the therapeutic agent is an anti-platinum chemoprotectant agent such as sodium thiosulfate or N-acetylcysteine).

In another aspect, the invention features a method of increasing hair cell survival in a subject (e.g., a mammalian subject, such as a human subject) in need thereof by administering to the subject a therapeutically effective amount of the auricular dosage form of any of the above aspects or embodiments of the invention, such as embodiments in which the therapeutic agent is a neurotrophin, an immunomodulating agent, an aural pressure modulating agent, a corticosteroid, an antimicrobial agent, an antagonist of truncated TrkC or truncated TrkB, a non-natural TrkB or TrkC agonist, a TrkB receptor agonist antibody, a TrkB receptor agonist compound, a TrkC receptor agonist antibody, a TrkC receptor agonist compound, an Atohl modulator, a neuroprotection agent, or a WNT modulator (e.g., embodiments in which the therapeutic agent is a neurotrophin selected from NT-3, NGF, BDNF, CNTF, GDNF, NT-4, FGF, IGF, EGF, PGF, MANF, CDNF, a pan-neurotrophin (e.g., PNT-1), a chimeric neurotrophin (e.g., a NGF/BDNF chimera), and combinations thereof, or embodiments in which the therapeutic agent is an anti-platinum chemoprotectant agent such as sodium thiosulfate or N- acetylcysteine).

In another aspect, the invention features a method of increasing SGN survival in a subject (e.g., a mammalian subject, such as a human subject) in need thereof by administering to the subject a therapeutically effective amount of the auricular dosage form of any of the above aspects or embodiments of the invention, such as embodiments in which the therapeutic agent is a neurotrophin, an immunomodulating agent, an aural pressure modulating agent, a corticosteroid, an antimicrobial agent, an antagonist of truncated TrkC or truncated TrkB, a non-natural TrkB or TrkC agonist, a TrkB receptor agonist antibody, a TrkB receptor agonist compound, a TrkC receptor agonist antibody, a TrkC receptor agonist compound, an Atohl modulator, a neuroprotection agent, WNT modulator, or an anti-platinum chemoprotectant agent (e.g., embodiments in which the therapeutic agent is a neurotrophin selected from NT-3, NGF, BDNF, CNTF, GDNF, NT-4, FGF, IGF, EGF, PGF, MANF, CDNF, a pan-neurotrophin (e.g., PNT-1 ), a chimeric neurotrophin (e.g., a NGF/BDNF chimera), and combinations thereof, or embodiments in which the therapeutic agent is an anti-platinum chemoprotectant agent such as sodium thiosulfate or N- acetylcysteine).

In some embodiments of any of the above aspects, the hair cell is a cochlear hair cell. In some embodiments of any of the above aspects, the cochlear hair cell is an inner hair cell. In some embodiments of any of the above aspects, the cochlear hair cell is an outer hair cell. In some embodiments of any of the above aspects, the hair cell is a vestibular hair cell. In some embodiments of any of the above aspects, the hair cell is a mammalian hair cell. In some embodiments, the mammalian hair cell is a human hair cell. In some embodiments of any of the above aspects, the SGN is a mammalian SGN. In some embodiments of any of the above aspects, the mammalian SGN is a human SGN.

In some embodiments of any of the above aspects, the method further includes evaluating the hearing of the subject prior to administering the auricular dosage form (e.g., evaluating hearing using standard tests, such as audiometry, auditory brainstem response (ABR), electrochocleography (ECOG), or otoacoustic emissions).

In some embodiments of any of the above aspects, the method further includes evaluating the hearing of the subject after administering the auricular dosage form (e.g., evaluating hearing using standard tests, such as audiometry, ABR, ECOG, or otoacoustic emissions).

In some embodiments of any of the above aspects, the method further includes evaluating the vestibular function of the subject prior to administering the auricular dosage form (e.g., evaluating vestibular function using standard tests, such as electronystagmogram (ENG) or videonystagmogram (VNG), posturography, rotary-chair testing, ECOG, vestibular evoked myogenic potentials (VEMP), or specialized clinical balance tests).

In some embodiments of any of the above aspects, the method further includes evaluating the vestibular function of the subject after administering the auricular dosage form (e.g., evaluating vestibular function using standard tests, such as ENG or VNG, posturography, rotary-chair testing, ECOG, VEMP, or specialized clinical balance tests).

In some embodiments of any of the above aspects, the auricular dosage form is locally administered. In some embodiments, the auricular dosage form is administered to the ear of the subject (e.g., administered to the round window). In some embodiments, the auricular dosage form is administered intratympanically or transtympanically (e.g., administered by transtympanic or intratympanic injection).

In some embodiments of any of the above aspects, the auricular dosage form is administered in an amount sufficient to prevent or reduce hearing loss, prevent or reduce vestibular dysfunction, prevent or reduce tinnitus, delay the development of hearing loss, delay the development of vestibular dysfunction, slow the progression of hearing loss, slow the progression of vestibular dysfunction, improve hearing, improve vestibular function, improve hair cell function, prevent or reduce hair cell damage, prevent, slow, or reduce hair cell death, promote or increase hair cell survival, increase hair cell numbers, promote or induce hair cell regeneration, improve SGN function, prevent or reduce SGN damage, prevent, slow, or reduce SGN death, promote or increase SGN survival, increase SGN numbers, promote or induce SGN regeneration, preserve ribbon synapses, promote or increase ribbon synapse formation, maintain the connections between hair cells and SGNs, or increase or restore the connections between hair cells and SGNs.

In an additional aspect, the invention features a kit containing the auricular dosage form of any of the above aspects or embodiments of the invention. In some embodiments, the kit contains a package insert instructing a user of the kit to administer the auricular dosage form to a subject (e.g., a mammalian subject, such as a human subject) in need thereof. In some embodiments, the subject is suffering from an otic disease, such as ceruminosis or ceruminosis associated with an otic disease or condition, ear pruritus, otitis externa, otalgia, tinnitus, vestibular dysfunction (e.g., vertigo, dizziness, or loss of balance), ear fullness, hearing loss, Meniere's disease, sensorineural hearing loss (e.g., noise-induced hearing loss, age-related hearing loss (presbycusis), ototoxic drug-induced hearing loss, hearing loss related to head trauma, hearing loss related to infection), auto immune ear disease, ototoxicity, excitotoxicity, hidden hearing loss, cochlear synaptopathy, endolymphatic hydrops, labyrinthitis, Ramsay Hunt's Syndrome, vestibular neuronitis, or microvascular compression syndrome, hyperacusis, presbystasis, central auditory processing disorder, auditory neuropathy, improvement of cochlea implant performance, or a combination thereof. In some embodiments, the package insert instructs a user of the kit to administer the auricular dosage form to the subject in order to prevent or mitigate sensory hair cell death in the subject. Definitions

As used herein, the term “about” refers to a value that is within 10% above or below the noted value. For instance, a value of “about 5 pL” refers to a quantity that is from 4.5 pL to 5.5 pL.

As used herein, the term “cochlear hair cell” refers to group of specialized cells in the inner ear that are involved in sensing sound. There are two types of cochlear hair cells: inner hair cells and outer hair cells. Damage to cochlear hair cells and genetic mutations that disrupt cochlear hair cell function are implicated in hearing loss and deafness.

As used herein, the terms “conservative mutation,” “conservative substitution,” or “conservative amino acid substitution” refer to a substitution of one or more amino acids for one or more different amino acids that exhibit similar physicochemical properties, such as polarity, electrostatic charge, and steric volume. These properties are summarized for each of the twenty naturally-occurring amino acids in Table 1 , below.

Table 1. Representative physicochemical properties of naturally-occurring amino acids

^†based on volume in A³: 50-100 is small, 100-150 is intermediate, 150-200 is large, and >200 is bulky

From this table it is appreciated that the conservative amino acid families include, e.g., (i) G, A, V, L, I, P, and M; (ii) D and E; (iii) C, S and T; (iv) H, K and R; (v) N and Q; and (vi) F, Y and W. A conservative mutation or substitution is therefore one that substitutes one amino acid for a member of the same amino acid family (e.g., a substitution of Ser for Thr or Lys for Arg). The formal charge of an amino acid residue at a particular pH, such as physiological pH (7.4), can be determined using the Henderson-Hasselbalch equation, pH = pKa + log [A-]/[HA], as applied to the side-chain functional group of the amino acid of interest, wherein “HA” designates the protonated form of the side-chain substituent and “A-” designates the deprotonated form of the side-chain substituent. It will be appreciated by one of skill in the art that the Henderson-Hasselbalch equation may be applied multiple times to the same amino acid for those that contain side-chains that undergo more than one ionization at the pH of interest (e.g., pH of 7.4), such as those that contain a phosphate substituent, among others. The formal charge of an amino acid as described herein refers to the charge of the predominant form (i.e., the form present in the highest quantity at chemical equilibrium) of the amino acid side chain substituent (e.g., “HA” or “A-”) as determined by the Henderson-Hasselbalch equation. As used herein, the terms “neurotrophin-3” and its abbreviation, “NT-3,” are used interchangeably and refer to the protein growth factor that exerts growth or survival activating effects on various neurons of the central and/or peripheral nervous system, as well as to the nucleic acid encoding the protein. The terms “neurotrophin-3” and its abbreviation, “NT-3,” refer not only to wild-type forms of NT-3, but also to variants of wild-type NT-3 proteins that retain (or improve upon) the neuronal growth or survival activating properties of wild-type NT-3, as well as to nucleic acids encoding such variants. The amino acid sequence and corresponding cDNA sequence of a wild-type form of human NT-3 are provided herein as

SEQ ID NOs: 1 and 2, which correspond to UniProtKB Accession No. P20783 and to CCDS 8538.1 , respectively. These sequences are shown in Table 2, below. The amino acid sequence of isoform 2 of wild-type human NT-3 and its corresponding cDNA sequence (SEQ ID NOs: 21 and 48), the amino acid sequence of the mature form of wild-type human NT-3 (SEQ ID NO: 8), and amino acid sequences of variants of the mature form of wild-type human NT-3 (SEQ ID NOs: 34-46) are provided in Table 3, herein. Table 2. Amino acid and cDNA nucleic acid sequences of wild-type human NT-3

The terms “neurotrophin-3” and its abbreviation, “NT-3,” as used herein include, for example, forms of the human NT-3 protein that have an amino acid sequence that is at least 85% identical to the amino acid sequence of SEQ ID NOs: 1 , 7, or 8 (e.g., 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, or 100% identical to the amino acid sequence of SEQ ID NO:

1 , 7, or 8) and/or forms of the human NT-3 protein that contain one or more substitutions, insertions, and/or deletions (e.g., one or more conservative and/or nonconservative amino acid substitutions, such as up to 5, 10, 15, 20, 25, or more, conservative or nonconservative amino acid substitutions) relative to a wild-type NT-3 protein. Similarly, the terms “neurotrophin-3” and its abbreviation, “NT-3,” as used herein include, for example, forms of the human NT-3 gene that correspond to a cDNA having a nucleic acid sequence that is at least 85% identical to the nucleic acid sequence of SEQ ID NO: 16 or 48 (e.g., 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, or 100% identical to the amino acid sequence of SEQ ID NO: 2 or 48). As used herein, the term “dose” refers to the quantity of a therapeutic agent, such as a neurotrophin described herein (e.g., NT-3) that is administered to a subject for the treatment of a disorder or condition, such as to treat or prevent sensory hair cell loss). A therapeutic agent as described herein may be administered in the form of an auricular dosage form in a single dose or in multiple doses for the treatment of a particular indication. In each case, the auricular dosage form agent may be administered using one or more unit dosage forms. For instance, a single dose of 1 mg of a therapeutic agent may be administered using, e.g., two 0.5 mg unit dosage forms of the therapeutic agent, four 0.25 mg unit dosage forms of the therapeutic agent, one single 1 mg unit dosage form of the therapeutic agent, and the like.

As used herein, the term “endogenous” describes a molecule (e.g., a metabolite, polypeptide, nucleic acid, or cofactor) that is found naturally in a particular organism (e.g., a human) or in a particular location within an organism (e.g., an organ, a tissue, or a cell, such as a human cell).

As used herein, the term “exogenous” describes a molecule (e.g., a small molecule, polypeptide, nucleic acid, or cofactor) that is not found naturally in a particular organism (e.g., a human) or in a particular location within an organism (e.g., an organ, a tissue, or a cell, such as a human cell).

Exogenous materials include those that are provided from an external source to an organism or to cultured matter extracted there from.

As used herein, the term “interfering RNA” refers to a RNA, such as a short interfering RNA (siRNA), micro RNA (miRNA), or short hairpin RNA (shRNA) that suppresses the expression of a target RNA transcript, for example, by way of (i) annealing to the target RNA transcript, thereby forming a nucleic acid duplex; and (ii) promoting the nuclease-mediated degradation of the RNA transcript and/or (iii) slowing, inhibiting, or preventing the translation of the RNA transcript, such as by sterically precluding the formation of a functional ribosome-RNA transcript complex or otherwise attenuating formation of a functional protein product from the target RNA transcript. Interfering RNAs as described herein may be provided to a patient, such as a human patient having a neurological disorder described herein, in the form of, for example, a single- or double-stranded oligonucleotide, or in the form of a vector (e.g., a viral vector) containing a transgene encoding the interfering RNA. Exemplary interfering RNA platforms are described, for example, in Lam et al. , Molecular Therapy - Nucleic Acids 4:e252 (2015); Rao et al. , Advanced Drug Delivery Reviews 61 :746-769 (2009); and Borel et al., Molecular Therapy 22:692-701 (2014), the disclosures of each of which are incorporated herein by reference in their entirety.

“Percent (%) sequence complementarity” with respect to a reference polynucleotide sequence is defined as the percentage of nucleic acids in a candidate sequence that are complementary to the nucleic acids in the reference polynucleotide sequence, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence complementarity. A given nucleotide is considered to be “complementary” to a reference nucleotide as described herein if the two nucleotides form canonical Watson-Crick base pairs. For the avoidance of doubt, Watson-Crick base pairs in the context of the present disclosure include adenine-thymine, adenine-uracil, and cytosine-guanine base pairs. A proper Watson-Crick base pair is referred to in this context as a “match,” while each unpaired nucleotide, and each incorrectly paired nucleotide, is referred to as a “mismatch.” Alignment for purposes of determining percent nucleic acid sequence complementarity can be achieved in various ways that are within the capabilities of one of skill in the art, for example, using publicly available computer software such as BLAST, BLAST-2, or Megalign software. Those skilled in the art can determine appropriate parameters for aligning sequences, including any algorithms needed to achieve maximal complementarity over the full length of the sequences being compared. As an illustration, the percent sequence complementarity of a given nucleic acid sequence, A, to a given nucleic acid sequence, B, (which can alternatively be phrased as a given nucleic acid sequence, A that has a certain percent complementarity to a given nucleic acid sequence, B) is calculated as follows:

100 multiplied by (the fraction X/Y) where X is the number of complementary base pairs in an alignment (e.g., as executed by computer software, such as BLAST) in that program’s alignment of A and B, and where Y is the total number of nucleic acids in B. It will be appreciated that where the length of nucleic acid sequence A is not equal to the length of nucleic acid sequence B, the percent sequence complementarity of A to B will not equal the percent sequence complementarity of B to A. As used herein, a query nucleic acid sequence is considered to be “completely complementary” to a reference nucleic acid sequence if the query nucleic acid sequence has 100% sequence complementarity to the reference nucleic acid sequence.

“Percent (%) sequence identity” with respect to a reference polynucleotide or polypeptide sequence is defined as the percentage of nucleic acids or amino acids in a candidate sequence that are identical to the nucleic acids or amino acids in the reference polynucleotide or polypeptide sequence, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity. Alignment for purposes of determining percent nucleic acid or amino acid sequence identity can be achieved in various ways that are within the capabilities of one of skill in the art, for example, using publicly available computer software such as BLAST, BLAST-2, or Megalign software. Those skilled in the art can determine appropriate parameters for aligning sequences, including any algorithms needed to achieve maximal alignment over the full length of the sequences being compared. For example, percent sequence identity values may be generated using the sequence comparison computer program BLAST. As an illustration, the percent sequence identity of a given nucleic acid or amino acid sequence, A, to, with, or against a given nucleic acid or amino acid sequence, B, (which can alternatively be phrased as a given nucleic acid or amino acid sequence, A that has a certain percent sequence identity to, with, or against a given nucleic acid or amino acid sequence, B) is calculated as follows:

100 multiplied by (the fraction X/Y) where X is the number of nucleotides or amino acids scored as identical matches by a sequence alignment program (e.g., BLAST) in that program’s alignment of A and B, and where Y is the total number of nucleic acids in B. It will be appreciated that where the length of nucleic acid or amino acid sequence A is not equal to the length of nucleic acid or amino acid sequence B, the percent sequence identity of A to B will not equal the percent sequence identity of B to A.

As used herein, the term “auricular dosage form” refers to a composition containing a therapeutic agent to be administered auricularly (e.g., intratympanically or transtympanically) to a patient, such as a mammal, e.g., a human, in order to prevent, treat or control a particular disease or condition affecting the mammal, e.g., diseases and conditions described herein.

As used herein, the term “pharmaceutically acceptable” refers to those compounds, materials, compositions and/or dosage forms, which are suitable for contact with the tissues of a patient, such as a mammal (e.g., a human) without excessive toxicity, irritation, allergic response and other problem complications commensurate with a reasonable benefit/risk ratio.

As used herein in the context of therapeutic treatment, the terms "provide" and "providing" refer to the delivery of a therapeutic agent to a subject (e.g., a mammalian subject, such as a human) in need of treatment, such as a subject experiencing or at risk of developing a neurological disorder described herein. A therapeutic agent may be provided to a subject in need thereof, for instance, by direct administration of the therapeutic agent to the subject, or by administration of a prodrug that is converted in vivo to the therapeutic agent upon administration of the prodrug to the subject. Exemplary prodrugs include, without limitation, esters, phosphates, and other chemical functionalities susceptible to hydrolysis upon administration to a subject. Prodrugs include those known in the art, such as those described, for instance, in Vig et al. , Adv. Drug Deliv. Rev. 65:1370-1385 (2013), and Huttunen et al. , Pharmacol. Rev. 63:750-771 (2011 ), the disclosures of each of which are incorporated herein by reference in their entirety.

As used herein, the term “sample” refers to a specimen (e.g., blood, blood component (e.g., serum or plasma), urine, saliva, amniotic fluid, cerebrospinal fluid, tissue (e.g., placental or myometrial), pancreatic fluid, chorionic villus sample, and cells) isolated from a patient.

As used herein, the phrases “specifically binds” and “binds” refer to a binding reaction which is determinative of the presence of a particular protein in a heterogeneous population of proteins and other biological molecules that is recognized, e.g., by a ligand with particularity. A ligand (e.g., a protein, proteoglycan, or glycosaminoglycan) that specifically binds to a protein will bind to the protein, e.g., with a KD of less than 100 nM. For example, a ligand that specifically binds to a protein may bind to the protein with a KD of up to 100 nM (e.g., between 1 pM and 100 nM). A ligand that does not exhibit specific binding to a protein or a domain thereof will exhibit a KD of greater than 100 nM (e.g., greater than 200 nM, 300 nM, 400 nM, 500 nM, 600 nm, 700 nM, 800 nM, 900 nM, 1 mM, 100 mM, 500 mM, or 1 mM) for that particular protein or domain thereof. A variety of assay formats may be used to determine the affinity of a ligand for a specific protein. For example, solid-phase ELISA assays are routinely used to identify ligands that specifically bind a target protein. See, e.g., Harlow & Lane, Antibodies, A Laboratory Manual, Cold Spring Harbor Press, New York (1988) and Harlow & Lane, Using Antibodies, A Laboratory Manual, Cold Spring Harbor Press, New York (1999), for a description of assay formats and conditions that can be used to determine specific protein binding.

As used herein, the terms “subject’ and “patient” are used interchangeably and refer to an organism, such as a mammal (e.g., a human) that receives therapy for the treatment or prevention of a disease or condition described herein, for example, for an otic disease or condition, such as ear pruritus, otitis externa, otalgia, tinnitus, vestibular dysfunction (e.g., vertigo, dizziness, loss of balance), ear fullness, hearing loss, Meniere's disease, sensorineural hearing loss (e.g., noise-induced hearing loss, age-related hearing loss (presbycusis), ototoxic drug-induced hearing loss, hearing loss related to head trauma, hearing loss related to infection), autoimmune ear disease, ototoxicity, excitotoxicity, hidden hearing loss, cochlear synaptopathy, endolymphatic hydrops, labyrinthitis, Ramsay Hunt's Syndrome, vestibular neuronitis, or microvascular compression syndrome, hyperacusis, presbystasis, central auditory processing disorder, auditory neuropathy, improvement of cochlea implant performance, or a combination thereof.

As used herein, the terms “increasing” and “decreasing” refer to modulating resulting in, respectively, greater or lesser amounts, of function, expression, or activity of a metric relative to a reference. For example, subsequent to administration of an auricular dosage form in a method described herein, the amount of a marker of a metric (e.g., hearing, such as hearing measured using standard clinical tests) as described herein may be increased or decreased in a subject by at least 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 98% or more relative to the amount of the marker prior to administration. Generally, the metric is measured subsequent to administration at a time that the administration has had the recited effect, e.g., at least one week, one month, 3 months, or 6 months, after a treatment regimen has begun. As used herein, the terms “effective amount,” “therapeutically effective amount,” and a “sufficient amount” of an auricular dosage form, polypeptide, small molecule, or viral vector described herein refer to a quantity sufficient to, when administered to the subject, including a mammal, for example a human, effect beneficial or desired results, including clinical results, and, as such, an “effective amount” or synonym thereto depends upon the context in which it is being applied. For example, in the context of treating sensorineural hearing loss or vestibular dysfunction, it is an amount of the auricular dosage form sufficient to achieve a treatment response as compared to the response obtained without administration of the auricular dosage form. The amount of a given auricular dosage form described herein that will correspond to such an amount will vary depending upon various factors, such as the given agent, the pharmaceutical formulation, the route of administration, the type of disease or disorder, the identity of the subject (e.g. age, sex, weight) or host being treated, and the like, but can nevertheless be routinely determined by one skilled in the art. Also, as used herein, a “therapeutically effective amount” of an auricular dosage form of the present disclosure is an amount which results in a beneficial or desired result in a subject as compared to a control. As defined herein, a therapeutically effective amount of an auricular dosage form of the present disclosure may be readily determined by one of ordinary skill by routine methods known in the art. Dosage regimen may be adjusted to provide the optimum therapeutic response.

As used herein, “locally” or “local administration” means administration at a particular site of the body intended for a local effect and not a systemic effect. Examples of local administration are epicutaneous, inhalational, intra-articular, intrathecal, intravaginal, intravitreal, intrauterine, intra-lesional administration, lymph node administration, intratumoral administration, administration to the inner ear (e.g., transtympanic or intratympanic injection), and administration to a mucous membrane of the subject, wherein the administration is intended to have a local and not a systemic effect.

As used herein, the term “plasmid” refers to a to an extrachromosomal circular double stranded DNA molecule into which additional DNA segments may be ligated. A plasmid is a type of vector, a nucleic acid molecule capable of transporting another nucleic acid to which it has been linked. Certain plasmids are capable of autonomous replication in a host cell into which they are introduced (e.g., bacterial plasmids having a bacterial origin of replication and episomal mammalian plasmids). Other vectors (e.g., non-episomal mammalian vectors) can be integrated into the genome of a host cell upon introduction into the host cell, and thereby are replicated along with the host genome. Certain plasmids are capable of directing the expression of genes to which they are operably linked.

As used herein, the terms “spiral ganglion neuron” and “SGN” refer to a type of specialized cell in the inner ear that innervates cochlear hair cells. There are two main classes of SGNs: Type I SGNs, which innervate inner hair cells and transmit sound information to the central nervous system (CNS), and Type II SGNs, which innervate outer hair cells and are not required for the transmission of sound information to the CNS.

As used herein, the term “vestibular hair cell” refers to group of specialized cells in the inner ear that are involved in sensing movement and contribute to the sense of balance and spatial orientation. Vestibular hair cells are located in the semicircular canals and otolith organs (e.g., utricle and saccule) of the inner ear. Damage to vestibular hair cells and genetic mutations that disrupt vestibular hair cell function are implicated in vestibular dysfunction such as vertigo and imbalance disorders. As used herein, the term “wild-type” refers to a genotype with the highest frequency for a particular gene in a given organism.

As used herein in the context of an otic disease or condition, the terms “treat” or “treatment” refer to therapeutic treatment, in which the object is to slow, delay, or halt the progression or development of an otic disease or condition, e.g., in a human subject.

Unless otherwise indicated, all amino acid sequences using three-letter code or one-letter code are depicted in the N-terminal to C-terminal direction.

As used herein, the terms “amino acid,” “amino acid monomer,” and “amino acid residue” are used interchangeably and refer to naturally-occurring alpha-amino acid molecules, such as those set forth in Table 1 , herein. The terms “amino acid,” “amino acid monomer,” and “amino acid residue” additionally refer to variants of the amino acid molecules set forth in Table 1 , such as beta-amino acids and gamma- amino acids, as well as amino acids in which the side chain is located on the amino nitrogen (such as the amino acid monomers that comprise peptoids, described, for example, in Kwon and Kodedk, J. Am. Chem. Soc. 129:1508-1509 (2007), the disclosure of which is incorporated herein by reference). The terms “amino acid,” “amino acid monomer,” and “amino acid residue” additionally refer to variants of the amino acid molecules set forth in Table 1 in which the amino nitrogen atom is modified, for example, by way of N-alkylation (e.g., N-methylation). Examples of N-methylated amino acids are described in Chatterjee et al., Acc. Chem. Res. 41 :1331 -1342 (2008), the disclosure of which is incorporated herein by reference). The terms amino acid,” “amino acid monomer,” and “amino acid residue” additionally refer to amino acid variants that are configured so as to be joined to a neighboring amino acid by way of a peptide bond isostere.

As used herein the terms “peptide” and “polypeptide” are used interchangeably and refer to polymers containing repeating amino acid molecules covalently bound to one another by way of amide bonds (also referred to as peptide bonds) or peptide bond isosteres).

As used herein, the term “antibody” (Ab) refers to an immunoglobulin molecule that specifically binds to, or is immunologically reactive with, a particular antigen, and includes polyclonal, monoclonal, genetically engineered, and otherwise modified forms of antibodies, including, but not limited to, chimeric antibodies, humanized antibodies, heteroconjugate antibodies (e.g., bi- tri- and quad-specific antibodies, diabodies, triabodies, and tetrabodies), and antigen-binding fragments of antibodies, including e.g., Fab', F(ab')2, Fab, Fv, rlgG, and scFv fragments. In some embodiments, two or more portions of an immunoglobulin molecule are covalently bound to one another, e.g., via an amide bond, a thioether bond, a carbon-carbon bond, a disulfide bridge, or by a linker, such as a linker described herein or known in the art. Antibodies also include antibody-like protein scaffolds, such as the tenth fibronectin type III domain (¹⁰Fn3), which contains BC, DE, and FG structural loops similar in structure and solvent accessibility to antibody complementarity-determining regions (CDRs). The tertiary structure of the ¹⁰Fn3 domain resembles that of the variable region of the IgG heavy chain, and one of skill in the art can graft, e.g., the CDRs of a reference antibody onto the fibronectin scaffold by replacing residues of the BC, DE, and FG loops of ¹⁰Fn3 with residues from the CDR-H1 , CDR-H2, or CDR-H3 regions, respectively, of the reference antibody.

The term “antigen-binding fragment,” as used herein, refers to one or more fragments of an antibody that retain the ability to specifically bind to a target antigen. The antigen-binding function of an antibody can be performed by fragments of a full-length antibody. The antibody fragments can be a Fab, F(ab’)2, scFv, SMIP, diabody, a triabody, an affibody, a nanobody, an aptamer, or a domain antibody. Examples of binding fragments encompassed of the term “antigen-binding fragment” of an antibody include, but are not limited to: (i) a Fab fragment, a monovalent fragment consisting of the VL, VH, CL, and CH1 domains; (ii) a F(ab')2 fragment, a bivalent fragment comprising two Fab fragments linked by a disulfide bridge at the hinge region; (iii) a Fd fragment consisting of the VH and CH1 domains; (iv) a Fv fragment consisting of the VL and VH domains of a single arm of an antibody, (v) a dAb including VH and VL domains; (vi) a dAb fragment (Ward et al., Nature 341 :544-546, 1989), which consists of a VH domain; (vii) a dAb which consists of a VH or a VL domain; (viii) an isolated CDR; and (ix) a combination of two or more isolated CDRs which may optionally be joined by a synthetic linker. Furthermore, although the two domains of the Fv fragment, VL and VH, are coded for by separate genes, they can be joined, using recombinant methods, by a linker that enables them to be made as a single protein chain in which the VL and VH regions pair to form monovalent molecules (known as single-chain Fv (scFv); see, e.g., Bird et al., Science 242:423-426, 1988, and Fluston et al., Proc. Natl. Acad. Sci. USA 85:5879-5883, 1988). These antibody fragments can be obtained using conventional techniques known to those of skill in the art, and the fragments can be screened for utility in the same manner as intact antibodies. Antigen-binding fragments can be produced by recombinant DNA techniques, enzymatic or chemical cleavage of intact immunoglobulins, or, in some embodiments, by chemical peptide synthesis procedures known in the art.

As used herein, the term “bispecific antibodies” refers to monoclonal, often human or humanized antibodies that have binding specificities for at least two different antigens.

As used herein, the term “chimeric” antibody refers to an antibody having variable domain sequences (e.g., CDR sequences) derived from an immunoglobulin of one source organism, such as rat or mouse, and constant regions derived from an immunoglobulin of a different organism (e.g., a human, another primate, pig, goat, rabbit, hamster, cat, dog, guinea pig, member of the bovidae family (such as cattle, bison, buffalo, elk, and yaks, among others), cow, sheep, horse, or bison, among others). Methods for producing chimeric antibodies are known in the art. See, e.g., Morrison, 1985, Science 229(4719): 1202-7; Oi et al, 1986, BioTechniques 4:214-221 ; Gillies et al, 1985, J. Immunol. Methods 125:191-202; U.S. Pat. Nos. 5,807,715; 4,816,567; and 4,816,397; incorporated herein by reference.

As used herein, the term “complementarity-determining region” (CDR) refers to a hypervariable region found both in the light chain and the heavy chain variable domains. The more highly conserved portions of variable domains are called the framework regions (FRs). As is appreciated in the art, the amino acid positions that delineate a hypervariable region of an antibody can vary, depending on the context and the various definitions known in the art. Some positions within a variable domain may be viewed as hybrid hypervariable positions in that these positions can be deemed to be within a hypervariable region under one set of criteria while being deemed to be outside a hypervariable region under a different set of criteria. One or more of these positions can also be found in extended hypervariable regions. The antibodies described herein may comprising modifications in these hybrid hypervariable positions. The variable domains of native heavy and light chains each comprise four framework regions that primarily adopt a b-sheet configuration, connected by three CDRs, which form loops that connect, and in some cases form part of, the b-sheet structure. The CDRs in each chain are held together in close proximity by the FR regions in the order FR1-CDR1-FR2-CDR2-FR3-CDR3-FR4 and, with the CDRs from the other antibody chains, contribute to the formation of the target binding site of antibodies (see Kabat et al, Sequences of Proteins of Immunological Interest (National Institute of Health, Bethesda, Md. 1987; incorporated herein by reference). As used herein, numbering of immunoglobulin amino acid residues is done according to the immunoglobulin amino acid residue numbering system of Kabat et al, unless otherwise indicated.

As used herein, the term “derivatized antibodies” refers to antibodies that are modified by a chemical reaction so as to cleave residues or add chemical moieties not native to an isolated antibody. Derivatized antibodies can be obtained by glycosylation, acetylation, pegylation, phosphorylation, amidation, derivatization by addition of known chemical protecting/blocking groups, proteolytic cleavage, linkage to a cellular ligand or other protein. Any of a variety of chemical modifications can be carried out by known techniques, including, without limitation, specific chemical cleavage, acetylation, formylation, metabolic synthesis of tunicamycin, etc. using established procedures. Additionally, the derivative can contain one or more non-natural amino acids, e.g., using amber suppression technology (see, e.g., US Patent No. 6,964,859; incorporated herein by reference).

As used herein, the term “diabodies” refers to bivalent antibodies comprising two polypeptide chains, in which each polypeptide chain includes VH and VL domains joined by a linker that is too short (e.g., a linker composed of five amino acids) to allow for intramolecular association of VH and VL domains on the same peptide chain. This configuration forces each domain to pair with a complementary domain on another polypeptide chain so as to form a homodimeric structure. Accordingly, the term “triabodies” refers to trivalent antibodies comprising three peptide chains, each of which contains one VH domain and one VL domain joined by a linker that is exceedingly short (e.g., a linker composed of 1 -2 amino acids) to permit intramolecular association of VH and VL domains within the same peptide chain.

In order to fold into their native structure, peptides configured in this way typically trimerize so as to position the VH and VL domains of neighboring peptide chains spatially proximal to one another to permit proper folding (see Holliger et al., Proc. Natl. Acad. Sci. USA 90:6444-48, 1993; incorporated herein by reference).

As used herein, the term “framework region” or “FW region” includes amino acid residues that are adjacent to the CDRs. FW region residues may be present in, for example, human antibodies, rodent- derived antibodies (e.g., murine antibodies), humanized antibodies, primatized antibodies, chimeric antibodies, antibody fragments (e.g., Fab fragments), single-chain antibody fragments (e.g., scFv fragments), antibody domains, and bispecific antibodies, among others.

As used herein, the term “heterospecific antibodies” refers to monoclonal, preferably human or humanized, antibodies that have binding specificities for at least two different antigens. Traditionally, the recombinant production of heterospecific antibodies is based on the co-expression of two immunoglobulin heavy chain-light chain pairs, where the two heavy chains have different specificities (Milstein et al., Nature 305:537, 1983). Similar procedures are disclosed, e.g., in WO 93/08829, U.S. Pat. Nos.

6,210,668; 6,193,967; 6,132,992; 6,106,833; 6,060,285; 6,037,453; 6,010,902; 5,989,530; 5,959,084; 5,959,083; 5,932,448; 5,833,985; 5,821 ,333; 5,807,706; 5,643,759, 5,601 ,819; 5,582,996, 5,496,549, 4,676,980, WO 91 /00360, WO 92/00373, EP 03089, Traunecker et al., EMBO J. 10:3655 (1991), Suresh et al., Methods in Enzymology 121 :210 (1986); incorporated herein by reference. Heterospecific antibodies can include Fc mutations that enforce correct chain association in multi-specific antibodies, as described by Klein et al, mAbs 4(6):653-663, 2012; incorporated herein by reference.

As used herein, the term “human antibody” refers to an antibody in which substantially every part of the protein (e.g., CDR, framework, CL, CH domains (e.g., CH1 , CH2, CH3), hinge, (VL, VH)) is substantially non-immunogenic in humans, with only minor sequence changes or variations. A human antibody can be produced in a human cell (e.g., by recombinant expression), or by a non-human animal or a prokaryotic or eukaryotic cell that is capable of expressing functionally rearranged human immunoglobulin (e.g., heavy chain and/or light chain) genes. Further, when a human antibody is a single chain antibody, it can include a linker peptide that is not found in native human antibodies. For example, an Fv can comprise a linker peptide, such as two to about eight glycine or other amino acid residues, which connects the variable region of the heavy chain and the variable region of the light chain. Such linker peptides are considered to be of human origin. Fluman antibodies can be made by a variety of methods known in the art including phage display methods using antibody libraries derived from human immunoglobulin sequences. See U.S. Patent Nos. 4,444,887 and 4,716,111 ; and PCT publications WO 98/46645; WO 98/50433; WO 98/24893; WO 98/16654; WO 96/34096; WO 96/33735; and WO 91/10741 ; incorporated herein by reference. Fluman antibodies can also be produced using transgenic mice that are incapable of expressing functional endogenous immunoglobulins, but which can express human immunoglobulin genes. See, e.g., PCT publications WO 98/24893; WO 92/01047; WO 96/34096; WO 96/33735; U.S. Patent Nos. 5,413,923; 5,625, 126; 5,633,425; 5,569,825; 5,661 ,016; 5,545,806;

5,814,318; 5,885,793; 5,916,771 ; and 5,939,598; incorporated by reference herein.

As used herein, the term “humanized antibodies” refers to forms of non-human (e.g., murine) antibodies that are chimeric immunoglobulins, immunoglobulin chains or fragments thereof (such as Fv, Fab, Fab', F(ab')2 or other target-binding subdomains of antibodies) which contain minimal sequences derived from non-human immunoglobulin. In general, the humanized antibody will comprise substantially all of at least one, and typically two, variable domains, in which all or substantially all of the CDR regions correspond to those of a non-human immunoglobulin. All or substantially all of the FR regions may also be those of a human immunoglobulin sequence. The humanized antibody can also comprise at least a portion of an immunoglobulin constant region (Fc), typically that of a human immunoglobulin consensus sequence. Methods of antibody humanization are known in the art. See, e.g., Riechmann et al., Nature 332:323-7, 1988; U.S. Patent Nos: 5,530,101 ; 5,585,089; 5,693,761 ; 5,693,762; and 6,180,370 to Queen et al; EP239400; PCT publication WO 91/09967; U.S. Patent No. 5,225,539; EP592106; and EP519596; incorporated herein by reference.

As used herein, the term “monoclonal antibody” refers to an antibody that is derived from a single clone, including any eukaryotic, prokaryotic, or phage clone, and not the method by which it is produced.

As used herein, the term “multi-specific antibodies” refers to antibodies that exhibit affinity for more than one target antigen. Multi-specific antibodies can have structures similar to full immunoglobulin molecules and include Fc regions, for example IgG Fc regions. Such structures can include, but not limited to, IgG-Fv, lgG-(scFv)2, DVD-lg, (scFv)2-(scFv)2-Fc and (scFv)2-Fc-(scFv)2. In case of lgG-(scFv)2, the scFv can be attached to either the N-terminal or the C- terminal end of either the heavy chain or the light chain. Exemplary multi-specific molecules have been reviewed by Kontermann, 2012, mAbs 4(2):182-197, Yazaki et al, 2013, Protein Engineering, Design & Selection 26(3):187- 193, and Grote et al, 2012, in Proetzel & Ebersbach (eds.), Antibody Methods and Protocols, Methods in Molecular Biology vol. 901 , chapter 16:247-263; incorporated herein by reference. In some embodiments, antibody fragments can be components of multi-specific molecules without Fc regions, based on fragments of IgG or DVD or scFv. Exemplary multi-specific molecules that lack Fc regions and into which antibodies or antibody fragments can be incorporated include scFv dimers (diabodies), trimers (triabodies) and tetramers (tetrabodies), Fab dimers (conjugates by adhesive polypeptide or protein domains) and Fab trimers (chemically conjugated), are described by Fludson and Souriau, 2003, Nature Medicine 9:129- 134; incorporated herein by reference.

As used herein, the term “primatized antibody” refers to an antibody comprising framework regions from primate-derived antibodies and other regions, such as CDRs and/or constant regions, from antibodies of a non-primate source. Methods for producing primatized antibodies are known in the art.

See e.g., U.S. Patent Nos. 5,658,570; 5,681 ,722; and 5,693,780; incorporated herein by reference. For instance, a primatized antibody or antigen-binding fragment thereof described herein can be produced by inserting the CDRs of a non-primate antibody or antigen-binding fragment thereof into an antibody or antigen-binding fragment thereof that contains one or more framework regions of a primate.

As used herein, the term “scFv” refers to a single-chain Fv antibody in which the variable domains of the heavy chain and the light chain from an antibody have been joined to form one chain. scFv fragments contain a single polypeptide chain that includes the variable region of an antibody light chain (VL) (e.g., CDR-L1 , CDR-L2, and/or CDR-L3) and the variable region of an antibody heavy chain (VH) (e.g., CDR-H1 , CDR-H2, and/or CDR-H3) separated by a linker. The linker that joins the VL and VH regions of a scFv fragment can be a peptide linker composed of proteinogenic amino acids. Alternative linkers can be used to so as to increase the resistance of the scFv fragment to proteolytic degradation (e.g., linkers containing D-amino acids), in order to enhance the solubility of the scFv fragment (e.g., hydrophilic linkers such as polyethylene glycol-containing linkers or polypeptides containing repeating glycine and serine residues), to improve the biophysical stability of the molecule (e.g., a linker containing cysteine residues that form intramolecular or intermolecular disulfide bonds), or to attenuate the immunogenicity of the scFv fragment (e.g., linkers containing glycosylation sites). scFv molecules are known in the art and are described, e.g., in US patent 5,892,019, Flo et al. , (Gene 77:51 , 1989); Bird et al., (Science 242:423, 1988); Pantoliano et al., (Biochemistry 30:10117, 1991 ); Milenic et al., (Cancer Research 51 :6363, 1991 ); and Takkinen et al., (Protein Engineering 4:837, 1991 ). The VL and VH domains of a scFv molecule can be derived from one or more antibody molecules. It will also be understood by one of ordinary skill in the art that the variable regions of the scFv molecules described herein can be modified such that they vary in amino acid sequence from the antibody molecule from which they were derived. For example, in one embodiment, nucleotide or amino acid substitutions leading to conservative substitutions or changes at amino acid residues can be made (e.g., in CDR and/or framework residues). Alternatively or in addition, mutations are made to CDR amino acid residues to optimize antigen binding using art recognized techniques. scFv fragments are described, for example, in WO 2011/084714; incorporated herein by reference.

The term “pharmaceutically acceptable solvate” as used herein means a compound as described herein wherein molecules of a suitable solvent are incorporated in the crystal lattice. A suitable solvent is physiologically tolerable at the dosage administered. For example, solvates may be prepared by crystallization, recrystallization, or precipitation from a solution that includes organic solvents, water, or a mixture thereof. Examples of suitable solvents are ethanol, water (for example, mono-, di-, tri-, tetra-, and penta-hydrates), A/-methylpyrrolidinone (NMP), dimethyl sulfoxide (DMSO), A/,A/-dimethylformamide (DMF), A/,A/-dimethylacetamide (DMAC), 1 ,3-dimethyl-2-imidazolidinone (DMEU), 1 ,3-dimethyl-3, 4,5,6- tetrahydro-2-(1 H)-pyrimidinone (DMPU), acetonitrile (ACN), propylene glycol, ethyl acetate, benzyl alcohol, 2-pyrrolidone, benzyl benzoate, and the like. When the solvate is water-based, the solvate is referred to as a hydrate.

The term “alkaline salt,” as used herein, represents a sodium or potassium salt of a compound. Alkaline salts may be monobasic or, if the number of acidic moieties (e.g., -COOH, -SO3H, or -P(0)(0H)_n moieties) permits, dibasic or tribasic.

The term “alkyl,” as used herein, refers to an acyclic straight or branched chain saturated hydrocarbon group, which, has from 1 to 25 carbons, unless otherwise specified. Alkyl groups are exemplified by hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, and the like.

The term “ammonium salt,” as used herein, represents an NHV salt of a compound. Ammonium salts may be monobasic or, if the number of acidic moieties (e.g., -COOH, -SO3H, or -P(0)(OH)_n moieties) permits, dibasic or tribasic.

The term “platinum-based antineoplastic agent,” as used herein, represents a coordination compound of Pt(ll) or Pt(IV). Platinum-based antineoplastic agents are known in the art as platins. Typically, platinum-based antineoplastic agents include at least two coordination sites at the platinum center that are occupied by nitrogenous spectator ligand(s). The nitrogenous spectator ligands are monodentate or bidentate ligands, in which the donor atom is an sp³- or sp²-hybridized nitrogen atom within the ligand. Non-limiting examples of nitrogenous spectator ligands are ammonia, 1 ,2- cyclohexanediamine, a picoline, phenanthrin, or 1 ,6-hexanediamine. Non-limiting examples of platinum- based antineoplastic agents include cisplatin, carboplatin, oxaliplatin, nedaplatin, triplatin tetranitrate, phenanthriplatin, picoplatin, and satraplatin.

The term “substantially neutral,” used herein, refers to a pH level of 5.5 to about 8.5, as measured at 20 °C.

The term “gelling agent,” as used herein, refers to pharmaceutically acceptable excipient known in the art to produce a gel upon mixing with a solvent (e.g., an aqueous solvent). Non-limiting examples of gelling agents include hyaluronan, a polyoxyethylene-polyoxypropylene block copolymer (e.g., a poloxamer), poly(lactic-co-glycolic) acid, polylactic acid, polycaprolactone, alginic acid or a salt thereof, polyethylene glycol, a cellulose, a cellulose ether, a carbomer (e.g., CARBOPOL®), agar-agar, gelatin, glucomannan, galactomannan (e.g., guar gum, locust bean gum, or tara gum), xanthan gum, chitosan, pectin, starch, tragacanth, carrageenan, polyvinylpyrrolidone, polyvinyl alcohol, paraffin, petrolatum, silicates, fibroin, and combinations thereof.

The term “hypertonic,” as used herein in reference to auricular dosage forms, represents an auricular dosage form having a calculated osmolarity of 300 mOsm/L to 7,000 mOsm/L (e.g., 300 mOsm/L to 2,500 mOsm/L), which corresponds to 300 mmol to 7,000 mmol (e.g., 300 mOsm/L to 2,500 mmol) of ions and/or neutral molecules produced by dissolution of platinum-deactivating agent and any ionic, non-polymeric excipients in 1 L of solvent having calculated osmolarity of 0 mOsm/L. For the purpose of the present disclosure, the calculated osmolarity does not include ions and/or neutral molecules produced from polymeric excipients (e.g., from a gelling agent). For the purpose of this disclosure, polymeric excipients (e.g., a gelling agents) are deemed as not contributing to the calculated osmolarity of the auricular dosage forms disclosed herein.

The term “tonicity agent,” as used herein, refers to a class of pharmaceutically acceptable excipients that are used to control osmolarity of auricular dosage forms. Non-limiting examples of a tonicity agent include substantially neutral buffering agents (e.g., phosphate buffered saline, tris buffer, or artificial perilymph), dextrose, mannitol, glycerin, potassium chloride, and sodium chloride (e.g., as a hypertonic, isotonic, or hypotonic saline). Artificial perilymph is an aqueous solution containing NaCI (120-130 mM), KCI (3.5 mM), CaCI₂ (1 .3-1 .5 mM), MgCI₂ (1 .2 mM), glucose (5.0-11 mM), and buffering agents (e.g., NaHC03 (25 mM) and NaH₂P04 (0.75 mM), or HEPES (20 mM) and NaOH (adjusted to pH of about 7.5)).

The term “intratympanic,” as used herein in reference to a route of administration, means delivery to the round window by injection or infusion through an ear canal with a temporarily removed or lifted tympanic membrane or through a port created through an auditory bulla into the middle ear of a subject.

The term “transtympanic,” as used herein, in reference to a route of administration, means delivery to the round window by injection or infusion across tympanic membrane. A transtympanic injection may be performed directly through the tympanic membrane or through a tube embedded in the tympanic membrane (e.g., through a tympanostomy tube or grommet).

The term “inner ear injection,” as used herein, refers to the direct injection of drug into the inner ear space.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a chart showing perilymph concentration of the therapeutic agent delivered using auricular dosage forms of the invention.

FIG. 2 is a chart showing the average threshold sound pressure levels at 4, 24, and 32 kHz measured during auditory brainstem response (ABR) tests in guinea pigs administered Gel 8 (n = 5 animals). ABR recording was performed before surgery or dosing and on the 7^th and 14^th day after auricular dosage form dosing.

DETAILED DESCRIPTION

In general, the invention provides auricular dosage forms and methods of their use. The auricular dosage forms described herein include a therapeutic agent, a gelling agent, and a permeation enhancing amount of glycerol. Glycerol used in the auricular dosage forms described herein may be superior relative to permeabilizers for delivery of a therapeutic agent to an inner ear, e.g., by facilitating permeation of the therapeutic agent across the round window membrane. Thus, the auricular dosage forms and methods described herein address the problem of the therapeutic agent delivery across the round window membrane. The delivery of therapeutic agents through the round window membrane and into the inner ear is a longstanding challenge, particularly for larger molecular weight agents, such as proteins, antibodies, nucleic acids, viral vectors, and nanoparticles, among others. Advantageously, the auricular dosage forms and methods described herein may be used to control not only the passage of therapeutic agents across the round window membrane but also to control release profiles of the therapeutic agents to the inner ear.

Without wishing to be bound by theory, glycerol provides high osmotic pressure in the auricular dosage forms described herein, thereby facilitating a therapeutic agent permeation across a round window membrane. Advantageously, small molecular weight

Upon accessing the inner ear, the therapeutic agents may migrate to a particular site at which they may exert their biological effect. Exemplary conditions that may be treated and/or prevented using the auricular dosage forms described herein are, without limitation, otic diseases or conditions, such as ceruminosis or ceruminosis associated with an otic disease or condition, ear pruritus, otitis externa, otalgia, tinnitus, vestibular dysfunction (e.g., vertigo, dizziness, or loss of balance), ear fullness, hearing loss, Meniere's disease, sensorineural hearing loss (e.g., noise-induced hearing loss, age-related hearing loss (presbycusis), ototoxic drug-induced hearing loss, hearing loss related to head trauma, hearing loss related to infection), autoimmune ear disease, ototoxicity, excitotoxicity, hidden hearing loss, cochlear synaptopathy, endolymphatic hydrops, labyrinthitis, Ramsay Hunt's Syndrome, vestibular neuronitis, or microvascular compression syndrome, hyperacusis, presbystasis, central auditory processing disorder, auditory neuropathy, improvement of cochlea implant performance, or a combination thereof. The auricular dosage forms described herein may additionally be used to prevent or mitigate sensory hair cell death. Particular embodiments of the auricular dosage forms that can be used for this purpose include those in which the therapeutic agent is a neurotrophin, an immunomodulating agent, an aural pressure modulating agent, a corticosteroid, an antimicrobial agent, an antagonist of truncated TrkC or truncated TrkB, a non-natural TrkB or TrkC agonist, a TrkB receptor agonist antibody, a TrkB receptor agonist compound, a TrkC receptor agonist antibody, a TrkC receptor agonist compound, a WNT modulator, or an anti-platinum chemoprotectant agent. For example, auricular dosage forms that are particularly suited for this indication are those in which the therapeutic agent is a neurotrophin selected from NT-3, NGF, BDNF, CNTF, GDNF, NT-4, FGF, IGF, EGF, PGF, MANF, CDNF, a pan-neurotrophin (PNT-1 ), a chimeric neurotrophin (e.g., an NGF/BDNF chimera), or a combination thereof, or an anti-platinum chemoprotectant agent, such as sodium thiosulfate or N-acetylcysteine.

Glycerol

Auricular dosage forms disclosed herein include glycerol as a permeabilizer. An auricular dosage form disclosed herein may include, e.g., at least 1 % (w/v) (e.g., at least 5% (w/v), at least 10% (w/v), at least 15% (w/v), at least 20% (w/v), at least 25% (w/v), at least 30% (w/v), at least 35% (w/v), or at least 40% (w/v); e.g., 90% (w/v) or less, 80% (w/v) or less, 75% (w/v) or less, 70% (w/v) or less, 65% (w/v) or less, 60% (w/v) or less, 55% (w/v) or less, 50% (w/v) or less, 45% (w/v) or less, 40% (w/v) or less, or 30% (w/v) or less; e.g., 1% (w/v) to 90% (w/v), 5% (w/v) to 90% (w/v), 10% (w/v) to 90% (w/v), 15% (w/v) to 90% (w/v), 20% (w/v) to 90% (w/v), 25% (w/v) to 90% (w/v), 30% (w/v) to 90% (w/v), 35% (w/v) to 90% (w/v), 40% (w/v) to 90% (w/v), 1% (w/v) to 80% (w/v), 5% (w/v) to 80% (w/v), 10% (w/v) to 80% (w/v),

15% (w/v) to 80% (w/v), 20% (w/v) to 80% (w/v), 25% (w/v) to 80% (w/v), 30% (w/v) to 80% (w/v), 35% (w/v) to 80% (w/v), 40% (w/v) to 80% (w/v), 1% (w/v) to 75% (w/v), 5% (w/v) to 75% (w/v), 10% (w/v) to 75% (w/v), 15% (w/v) to 75% (w/v), 20% (w/v) to 75% (w/v), 25% (w/v) to 75% (w/v), 30% (w/v) to 75% (w/v), 35% (w/v) to 75% (w/v), 40% (w/v) to 75% (w/v), 1% (w/v) to 70% (w/v), 5% (w/v) to 70% (w/v),

10% (w/v) to 70% (w/v), 15% (w/v) to 70% (w/v), 20% (w/v) to 70% (w/v), 25% (w/v) to 70% (w/v), 30% (w/v) to 70% (w/v), 35% (w/v) to 70% (w/v), 40% (w/v) to 70% (w/v), 1% (w/v) to 65% (w/v), 5% (w/v) to 65% (w/v), 10% (w/v) to 65% (w/v), 15% (w/v) to 65% (w/v), 20% (w/v) to 65% (w/v), 25% (w/v) to 65% (w/v), 30% (w/v) to 65% (w/v), 35% (w/v) to 65% (w/v), 40% (w/v) to 65% (w/v), 1 % (w/v) to 60% (w/v),

5% (w/v) to 60% (w/v), 10% (w/v) to 60% (w/v), 15% (w/v) to 60% (w/v), 20% (w/v) to 60% (w/v), 25% (w/v) to 60% (w/v), 30% (w/v) to 60% (w/v), 35% (w/v) to 60% (w/v), 40% (w/v) to 60% (w/v), 1% (w/v) to 55% (w/v), 5% (w/v) to 55% (w/v), 10% (w/v) to 55% (w/v), 15% (w/v) to 55% (w/v), 20% (w/v) to 55% (w/v), 25% (w/v) to 55% (w/v), 30% (w/v) to 55% (w/v), 35% (w/v) to 55% (w/v), 40% (w/v) to 55% (w/v), 1 % (w/v) to 50% (w/v), 5% (w/v) to 50% (w/v), 10% (w/v) to 50% (w/v), 15% (w/v) to 50% (w/v), 20% (w/v) to 50% (w/v), 25% (w/v) to 50% (w/v), 30% (w/v) to 50% (w/v), 35% (w/v) to 50% (w/v), 40% (w/v) to 50% (w/v), 1% (w/v) to 45% (w/v), 5% (w/v) to 45% (w/v), 10% (w/v) to 45% (w/v), 15% (w/v) to 45% (w/v),

20% (w/v) to 45% (w/v), 25% (w/v) to 45% (w/v), 30% (w/v) to 45% (w/v), 35% (w/v) to 45% (w/v), 40% (w/v) to 45% (w/v), 1% (w/v) to 40% (w/v), 5% (w/v) to 40% (w/v), 10% (w/v) to 40% (w/v), 15% (w/v) to 40% (w/v), 20% (w/v) to 40% (w/v), 25% (w/v) to 40% (w/v), 30% (w/v) to 40% (w/v), 35% (w/v) to 40% (w/v), 1% (w/v) to 35% (w/v), 5% (w/v) to 35% (w/v), 10% (w/v) to 35% (w/v), 15% (w/v) to 35% (w/v),

20% (w/v) to 35% (w/v), 25% (w/v) to 35% (w/v), 30% (w/v) to 35% (w/v), 1% (w/v) to 30% (w/v), 5% (w/v) to 30% (w/v), 10% (w/v) to 30% (w/v), 15% (w/v) to 30% (w/v), 20% (w/v) to 30% (w/v), 25% (w/v) to 30% (w/v), 1% (w/v) to 25% (w/v), 5% (w/v) to 25% (w/v), 10% (w/v) to 25% (w/v), 15% (w/v) to 25% (w/v), or 20% (w/v) to 25% (w/v)) of glycerol.

Therapeutic Agents

Examples of therapeutic agents that may be incorporated into the auricular dosage forms described herein are neurotrophins, immunomodulating agents, aural pressure modulating agents, corticosteroids, antimicrobial agents, antagonists of truncated TrkC or truncated TrkB, non-natural TrkB or TrkC agonists, TrkB receptor agonist antibodies or antigen-binding fragments thereof, TrkB receptor agonist compounds, TrkC receptor agonist antibodies or antigen-binding fragments thereof, TrkC receptor agonist compounds, neuroprotection agents, Atohl modulators (e.g., an Atohl polypeptide or a nucleic acid vector engineered to express Atohl , e.g., human Atohl (Hathl )), WNT modulators, and anti platinum chemoprotectant agents (e.g., sodium thiosulfate or N-acetylcysteine).

Neurotrophins

The therapeutic agent may be, for example, a neurotrophin selected from neurotrophin-3 (NT-3), nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), glial cell-line derived neurotrophic factor (GDNF), neurotrophin-4 (NT-4), fibroblast growth factor (FGF), insulin-like growth factor (IGF), epidermal growth factor (EGF), platelet-derived growth factor (PGF), mesencephalic astrocyte-derived neurotrophic factor (MANF), cerebral dopamine neurotrophic factor (CDNF), a pan-neurotrophin (e.g., PNT-1 ), a chimeric neurotrophin (e.g., an NGF/BDNF chimera), and combinations thereof.

In some embodiments, the neurotrophic factor is NT-3. The NT-3 may have an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NOs: 1 , 7, or 8. The NT-3 may have, for example, an amino acid sequence that differs from the amino acid sequence of any one of SEQ ID NOs: 1 , 7, or 8 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. The NT-3 may be an NT-3 variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, or more) amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOs: 1 , 7, and 8. The NT-3 variant may have, for example, the sequence of any one of SEQ ID NOs: 34-46. In some embodiments, the NT-3 variant has the sequence of SEQ ID NO: 35. In some embodiments, the NT-3 variant has the sequence of SEQ ID NO: 43. In some embodiments, the NT-3 variant has the sequence of SEQ ID NO: 44. The NT-3 may be encoded by a nucleic acid having the sequence of SEQ ID NO: 2 or SEQ ID NO: 56. In some embodiments, the neurotrophic factor is NGF. The NGF may have an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NOs: 5 or 6. The NGF may have, for example, an amino acid sequence that differs from the amino acid sequence of SEQ ID NOs: 5 or 6 by only one or more conservative amino acid substitutions, such as by up to 11 , up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. The NGF may be an NGF variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, or more) amino acid substitutions relative to the amino acid sequence of SEQ ID NOs: 5 or 6. In some embodiments, the NGF variant has the sequence any one of SEQ ID NOs: 20- 23. In some embodiments, the NGF may be an NGF variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) amino acid substitutions relative to the amino acid sequence of SEQ ID NOs: 5 or 6 and one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10 or more) deleted amino acids relative to the amino acid sequence of SEQ ID NOs: 5 or 6. In some embodiments, the NGF variant has the sequence of SEQ ID NO: 24. The NGF may be encoded by a nucleic acid having the sequence of SEQ ID NO: 55 or SEQ ID NO: 62.

In some embodiments, the neurotrophic factor is NT-4. The NT-4 may have an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NOs: 9 or 10. The NT-4 may have, for example, an amino acid sequence that differs from the amino acid sequence of SEQ ID NOs: 9 or 10 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. The NT-4 may be an NT-4 variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, or more) amino acid substitutions relative to the amino acid sequence of SEQ ID NOs: 9 or 10. The NT-4 may be encoded by a nucleic acid having the sequence of SEQ ID NO: 57.

In some embodiments, the neurotrophic factor is BDNF. The BDNF may have an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of any one of SEQ ID NOs: 11 -16. The BDNF may have, for example, an amino acid sequence that differs from the amino acid sequence of any one of SEQ ID NOs: 11 -16 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. The BDNF may be a BDNF variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, or more) amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOs: 11 -16. The BDNF may be encoded by a nucleic acid having the sequence of any one of SEQ ID NOs: 58-61 .

In some embodiments, the neurotrophin is a pan-neurotrophin, such as PNT-1 . The PNT-1 may have an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 17. The PNT-1 may have, for example, an amino acid sequence that differs from the amino acid sequence of SEQ ID NO: 17 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. The PNT-1 may be a PNT-1 variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, or more) amino acid substitutions relative to the amino acid sequence of SEQ ID NO: 17. In some embodiments, the PNT-1 variant has the sequence any one of SEQ ID NOs: 25-28 or 31 -33.

In some embodiments, the neurotrophin is a chimeric neurotrophin. In some embodiments, the chimeric neurotrophin is an NGF/BDNF chimera. The chimeric neurotrophin may have an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of any one of SEQ ID NOs: 18, 19, 29, or 30. The chimeric neurotrophin may have, for example, an amino acid sequence that differs from the amino acid sequence of any one of SEQ ID NOs: 18, 19, 29, or 30 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. The chimeric neurotrophin may be a chimeric neurotrophin variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, or more) amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOs: 18, 19, 29, or 30.

In some embodiments, the neurotrophic factor is CNTF. The CNTF may have an amino acid sequence having at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of SEQ ID NO: 47. The CNTF may have, for example, an amino acid sequence that differs from the amino acid sequence of SEQ ID NO: 47 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. The CNTF may be a CNTF variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, or more) amino acid substitutions relative to the amino acid sequence of SEQ ID NO: 47. The CNTF may be encoded by a nucleic acid having the sequence of SEQ ID NO: 63.

In some embodiments, the neurotrophic factor is IGF. The IGF may have an amino acid sequence of IGF1 and have at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of any one of SEQ ID NOs: 48-51 . The IGF may have an amino acid sequence of IGF2 and have at least 85% sequence identity (e.g., at least 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.9%, 99.99%, or 100% sequence identity) to the amino acid sequence of any one of SEQ ID NOs: 52-54. The IGF (e.g., IGF1) may have, for example, an amino acid sequence that differs from the amino acid sequence of any one of SEQ ID NOs: 48-51 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. The IGF (e.g., IGF2) may have, for example, an amino acid sequence that differs from the amino acid sequence of any one of SEQ ID NOs: 52-54 by only one or more conservative amino acid substitutions, such as by up to 25, up to 20, up to 15, up to 10, or up to 5 conservative amino acid substitutions. The IGF may be an IGF1 variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, or more) amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOs: 48-51 . The IGF may be an IGF2 variant having an amino acid sequence with one or more (e.g., 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, or more) amino acid substitutions relative to the amino acid sequence of any one of SEQ ID NOs: 52-54. The IGF may be IGF1 and may be encoded by a nucleic acid having the sequence of any one of SEQ ID NOs: 64-66. The IGF may be IGF2 and may be encoded by a nucleic acid having the sequence of SEQ ID NO: 67 or SEQ ID NO: 68. In some embodiments, the therapeutic agent is a glial cell line-derived neurotrophic factor family ligand, a neuropoietic cytokine, an anti-inflammatory cytokine, a neuroprotection agent, growth differentiation factor 11 , erythropoietin (EPO), granulocyte-colony stimulating factor, granulocyte- macrophage colony stimulating factor, growth differentiation factor-9, thrombopoietin, transforming growth factor alpha (TGF-a), stromal cell-derived factor 1 , myostatin (growth differentiation factor 8), parathyroid hormone, parathyroid hormone related peptide, interleukin 1 receptor antagonist, fibroblast growth factor 18, high-mobility group protein 2, glucocorticoid receptor, fibroblast growth factor 9, hepatocyte growth factor, or a TGFp-superfamily protein.

In some embodiments, the therapeutic agent is a glial cell line-derived neurotrophic factor family ligand selected from glial cell line-derived neurotrophic factor (GDNF), neurturin, artemin, and persephin.

Exemplary neurotrophin sequences are provided in Table 3, below.

Table 3. Neurotrophin Sequences

Neuropoietic cytokines

Therapeutic agents that may be incorporated into the auricular dosage forms and methods described herein include neuropoietic cytokines, such as interleukin-6, interleukin-11 , inteleukin-27, leukemia inhibitory factor, cardiotrophin 1 , neuropoietin, cardiotrophin-like cytokine, and fibroblast growth factor 2.

Anti-inflammatory cytokines

Therapeutic agents that may be incorporated into the auricular dosage forms and methods described herein include anti-inflammatory cytokines. Examples of anti-inflammatory cytokines useful in conjunction with the auricular dosage forms and methods described herein are interleukin-4 and interleukin-10.

Neuroprotection agents

Therapeutic agents that may be incorporated into the auricular dosage forms and methods described herein include neuroprotection agents. For example, the auricular dosage forms described herein may contain a neuroprotection agent selected from neuregulin-1 and vascular endothelial growth factor (VEGF).

TGF 3 superfamily member proteins

Therapeutic agents that may be incorporated into the auricular dosage forms and methods described herein include TGFp superfamily member proteins. For example, the auricular dosage forms described herein may contain a TGFp-superfamily protein selected from TGFp, TGFp3, BMP2, and BMP7.

Immunomodulating agents

Therapeutic agents that may be incorporated into the auricular dosage forms and methods described herein include immunomodulating agents. For example, the auricular dosage forms described herein may contain an immunomodulating agent selected from the group including anti-TNF agents (e.g., anti-TNF antibodies, such as infliximab adalimumab, and golimumab; fusion proteins, such as etanercept; TACE inhibitors; IKK inhibitors; or calcineurin inhibitors) and toll-like receptor inhibitors.

Anti-platinum chemoprotectant agents

Therapeutic agents that may be incorporated into the auricular dosage forms and methods described herein include anti-platinum chemoprotectant agents. Without wishing to be bound by theory, anti-platinum chemoprotectant agents are believed to reduce or eliminate the toxicity of platin-based antineoplastic agents by competitively ligating and substantially coordinatively saturating the platinum centers present in the platinum-based antineoplastic agents. The concentration of an anti-platinum chemoprotectant agent in an auricular dosage form (e.g., a pharmaceutical dosage form) of the invention may be, e.g., at least 0.05M (e.g., at least 0.1 M, at least 0.2M, at least 0.3M, at least 0.4M, at least 0.5M, or at least 1 M). The concentration of an anti-platinum chemoprotectant agent in an auricular dosage form (e.g., an auricular unit dosage form) of the invention may be, e.g., about 2.5M or less (e.g., 2.0M or less,

1 .5M or less, 1 .0M or less, 0.5M or less, about 0.3M or less, or about 0.2M or less). Non-limiting examples of the concentrations of an anti-platinum chemoprotectant agent in an auricular dosage form (e.g., an auricular unit dosage form) of the invention may be, e.g., about 0.05M to about 1 .5 M, about 0.05M to about 0.5M, about 0.05M to about 0.2M, about 0.05M to about 0.1 M, about 0.1 M to about 1 .5M, about 0.1 M to about 0.5M, about 0.1 M to about 0.2M, about 0.2M to about 1 .5M, about 0.2M to about

0.5M, about 0.5M to about 1 .5M, 0.05M to about 1 .0 M, about 0.05M to about 0.5M, about 0.05M to about 0.2M, about 0.05M to about 0.1 M, about 0.1 M to about 1 .0M, about 0.1 M to about 0.5M, about 0.1 M to about 0.2M, about 0.2M to about 1 .0M, about 0.2M to about 0.5M, or about 0.5M to about 1 .0M, or about 1 .0M to about 1 .5M. Preferably, the concentration of an anti-platinum chemoprotectant agent in an auricular dosage form (e.g., an auricular unit dosage form) of the invention is 1 .0M to about 1 .5M.

Anti-platinum chemoprotectant agents are known in the art. Non-limiting examples of anti platinum chemoprotectant agents include an alkaline or ammonium thiosulfate salt (e.g., sodium thiosulfate, potassium thiosulfate, or ammonium thiosulfate) or a solvate thereof (e.g., sodium thiosulfate pentahydrate), an alkaline diethyldithiocarbamate salt, amifostine, methionine, N-acetylcysteine, cysteine, 2-aminoethanethiol, glutathione (GSH) or a C1-C6 alkyl ester thereof (e.g., glutathione ethyl ester: y-Glu- Cys-Gly-OEt) or a salt thereof, lysine or a salt thereof, histidine or a salt thereof, arginine or a salt thereof, ethylene diamine tetraacetic acid or a salt thereof (e.g., an alkaline salt), dimercaprol, dimercaptosuccinic acid or a salt thereof (e.g., an alkaline salt), dimercapto-propane sulfonate salt (e.g., alkaline salt or ammonium salt), penicillamine, a-lipoic acid or a salt thereof (e.g., an alkaline or ammounium salt), or fursultiamine or a salt thereof. Preferably, the anti-platinum chemoprotectant agent is an alkaline or ammonium thiosulfate salt. More preferably, the anti-platinum chemoprotectant agent is sodium thiosulfate.

Viral vectors

Viral genomes provide a rich source of vectors that can be used for the efficient delivery of a gene of interest into the genome of a target cell (e.g., a mammalian cell, such as a human cell). Viral genomes are particularly useful vectors for gene delivery because the polynucleotides contained within such genomes are typically incorporated into the genome of a target cell by generalized or specialized transduction. These processes occur as part of the natural viral replication cycle, and do not require added proteins or reagents to induce gene integration. Examples of viral vectors that may be incorporated into the auricular dosage forms described herein are adeno-associated viral (AAV) vectors (e.g., AAV1 , AAV2, AAV3, AAV4, AAV5, AAV6, AAV7, AAV8, AAV9, AAV10, rh10, rh39, rh43, rh74, Anc80, Anc80L65, DJ/8, DJ/9, 7m8, PHP.B, PHP.eb, and PHP.S), retrovirus, adenovirus (e.g., Ad5,

Ad26, Ad34, Ad35, and Ad48), parvovirus (e.g., adeno-associated viruses), coronavirus, negative strand RNA viruses such as orthomyxovirus (e.g., influenza virus), rhabdovirus (e.g., rabies and vesicular stomatitis virus), paramyxovirus (e.g. measles and Sendai), positive strand RNA viruses, such as picornavirus and alphavirus, and double stranded DNA viruses including adenovirus, herpesvirus (e.g., Herpes Simplex virus types 1 and 2, Epstein-Barr virus, cytomegalovirus), and poxvirus (e.g., vaccinia, modified vaccinia Ankara (MVA), fowlpox and canarypox). Other examples of viral vectors that may be used in conjunction with the auricular dosage forms and methods described herein are Norwalk virus, togavirus, flavivirus, reoviruses, papovavirus, hepadnavirus, and hepatitis virus, among others. Examples of retroviruses include: avian leukosis-sarcoma, mammalian C-type, B-type viruses, D-type viruses, HTLV-BLV group, lentivirus, spumavirus (Coffin, J. M., Retroviridae: The viruses and their replication, In Fundamental Virology, Third Edition, B. N. Fields, et al ., Eds., Lippincott-Raven Publishers, Philadelphia,

1996). Other examples include murine leukemia viruses, murine sarcoma viruses, mouse mammary tumor virus, bovine leukemia virus, feline leukemia virus, feline sarcoma virus, avian leukemia virus, human T-cell leukemia virus, baboon endogenous virus, Gibbon ape leukemia virus, Mason Pfizer monkey virus, simian immunodeficiency virus, simian sarcoma virus, Rous sarcoma virus and lentiviruses. Other examples of vectors are described, for example, in US Patent No. 5,801 ,030, the disclosure of which is incorporated herein by reference as it pertains to viral vectors for use in gene therapy.

Antibodies and antigen-binding fragments thereof

In some embodiments, the therapeutic agent is an antibody or antigen-binding fragment thereof, such as an antibody or antigen-binding fragment thereof that binds TrkB, TrkC, or a receptor thereof. The antibody or antigen-binding fragment thereof may be, for example, a monoclonal antibody or antigen binding fragment thereof, a polyclonal antibody or antigen-binding fragment thereof, a humanized antibody or antigen-binding fragment thereof, a bispecific antibody or antigen-binding fragment thereof, a dual-variable immunoglobulin domain, a single-chain Fv molecule (scFv), a diabody, a triabody, a nanobody, an antibody-like protein scaffold, a Fv fragment, a Fab fragment, a F(ab’)2 molecule, or a tandem di-scFv.

Exemplary TrkB- and TrkC-binding antibodies useful in conjunction with the auricular dosage forms and methods described herein are those produced by the cell lines shown in Table 4, below. Other TrkB- and TrkC-binding antibodies that may be used in conjunction with the auricular dosage forms and methods described herein are recited in WO 2017/019907.

Table 4. Examples of hybridoma lines producing TrkB- and TrkC-binding antibodies

Additional agents

Therapeutic agents that may be incorporated into the auricular dosage forms described herein further include liposomes, vesicles, synthetic vesicles, exosomes, synthetic exosomes, dendrimers, and nanoparticles. Additional examples of therapeutic agents that may be used in conjunction with the auricular dosage forms and methods described herein are small molecules, such as those that are not naturally round window membrane-penetrant. Further examples of such therapeutic agents are interfering RNA molecules, such as a short interfering RNA (siRNA), a short hairpin RNA (shRNA), and a micro RNA (miRNA). Exemplary interfering RNA molecules are those at are at least 85% complementary to, and/or that anneal to, a target nucleic acid of interest, thereby suppressing the expression of the target nucleic acid.

Additional examples of therapeutic agents that may be incorporated into the auricular dosage forms and methods described herein are, without limitation, antimicrobial agents, an arylcycloalkylamine, an elipticine derivative, anti-apoptotic agents, c-JNK inhibitors, antioxidants, NSAIDs, analgesics, neuroprotection agents, glutamate modulators, interleukin 1 modulators, interleukin-1 antagonists, corticosteroids, anti-TNF agents, calcineurin Inhibitors, IKK inhibitors, Interleukin inhibitors, platelet activating factor antagonists, TNF-a converting enzyme (TACE) inhibitors, Toll-like receptor inhibitors, autoimmune agents, IL-1 modulators, RNA interference agents, aquaporin modulators, estrogen-related receptor beta modulators, GAP junction proteins, vasopressin receptor modulators, NMDA receptor modulators, ENaC receptor modulators, osmotic diuretics, progesterone receptors, prostaglandins, cytotoxic agents, cytoprotective agents, anti-intercellular adhesion molecule-1 antibody, Atohl modulators (e.g., an Atohl polypeptide or a nucleic acid vector engineered to express Atohl , e.g., human Atohl (Hathl )), Mathl modulators, BRN-3 modulators, carbamates, estrogen receptors, fatty acids, gamma- secretase inhibitors, glutamate-receptor modulators, a neurotrophic agent, salicylic acid, nicotine, retinoblastoma protein modulators, ion channel blockers, thyroid hormone receptor modulators, TRPV modulators, adenosine modulators, KCNQ modulators, P2X modulators, CNS modulating agents, anticholinergics, antihistamines, GABA receptor modulators, neurotransmitter reuptake inhibitors, thyrotropin-releasing hormones, free radical modulators, metal atom chelators, mitochondrial modulators, nitric oxide synthase modulators, sirtuin modulators, purinergic receptor modulators, nucleic acid polymer antagonists, small molecule antagonists, polypeptide antagonists, a neurotrophin variant, a WNT modulator, an anti-platinum chemoprotectant agent, a protein kinase C beta modulator, a repulsive guidance molecule a (RGMa) inhibitor, a neogenin inhibitor, a SK2 channel activator, a BK channel activator, a sphingosine-1 -phosphate receptor modulator, a sternness driver, a differentiation inhibitor, an N-Methyl-D-Aspartate (NMDA) receptor antagonist, a histone deacetylase (FIDAC) inhibitor, a glycogen synthase kinase inhibitor (e.g., GSK3p and/or GSK3a inhibitor), a proteasome inhibitor, an EZFI2/FIMT inhibitor, a notch inhibitor, ebselen, ancrod, an a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) glutamate-positive allosteric modulator, D-methionine, an antagonist of histamine type 4 receptors, a chemotherapeutic accumulation reducer, choline ester, plant alkaloid, reversible cholinesterase inhibitor, acetylcholine release promoter, anti-adrenergic agent, a sympathomimetic agent, an antineoplastic agent, R(+)-N-propargyl-1-aminoindan, and R-azasetron besylate.

Other therapeutic agents that may be used in conjunction with the auricular dosage forms and methods described herein are recited in WO 2017/019907 and WO 2018/005830, the disclosures of which are incorporated herein by reference. Methods of Treatment

The auricular dosage forms described herein may be administered to a subject (e.g., a mammalian subject, such as a human patient) to treat and/or prevent one or more of a variety of pathologies. For example, the auricular dosage forms described herein may be used to deliver a therapeutic agent across the round window membrane of a subject (e.g., a mammalian subject, such as a human patient) so as to treat an otic disease, such as ceruminosis or ceruminosis associated with an otic disease or condition, ear pruritus, otitis externa, otalgia, tinnitus, vestibular dysfunction (e.g., vertigo, dizziness, or loss of balance), ear fullness, hearing loss, Meniere's disease, sensorineural hearing loss (e.g., noise-induced hearing loss, age-related hearing loss (presbycusis), ototoxic drug-induced hearing loss, hearing loss related to head trauma, hearing loss related to infection), autoimmune ear disease, ototoxicity, excitotoxicity, hidden hearing loss, cochlear synaptopathy, endolymphatic hydrops, labyrinthitis, Ramsay Flunt's Syndrome, vestibular neuronitis, or microvascular compression syndrome, hyperacusis, presbystasis, central auditory processing disorder, auditory neuropathy, improvement of cochlea implant performance, or a combination thereof.

Subjects that may be treated as described herein are subjects having or at risk of developing sensorineural hearing loss, deafness, auditory neuropathy, tinnitus, and/or vestibular dysfunction (e.g., subjects having or at risk of developing hearing loss, vestibular dysfunction, or both). The auricular dosage forms and methods described herein can be used to treat subjects having or at risk of developing damage to cochlear hair cells (e.g., damage related to acoustic trauma, disease or infection, head trauma, ototoxic drugs, or aging), subjects having or at risk of developing damage to vestibular hair cells (e.g., damage related to disease or infection, head trauma, ototoxic drugs, or aging), subjects having or at risk of developing damage to spiral ganglion neurons (SGNs) (e.g., damage related to acoustic trauma, disease or infection, head trauma, ototoxic drugs, or aging), subjects having or at risk of developing SGN degeneration, subjects having or at risk of developing sensorineural hearing loss, deafness, auditory neuropathy, or tinnitus, subjects having or at risk of developing vestibular dysfunction (e.g., dizziness, vertigo, or imbalance), subjects having tinnitus (e.g., tinnitus alone, or tinnitus that is associated with sensorineural hearing loss or vestibular dysfunction), subjects having a genetic mutation associated with hearing loss and/or vestibular dysfunction, or subjects with a family history of hereditary hearing loss, deafness, auditory neuropathy, tinnitus, or vestibular dysfunction. In some embodiments, the subject has hearing loss and/or vestibular dysfunction that is associated with or results from damage to or loss of hair cells (e.g., cochlear or vestibular hair cells) or SGNs. The methods described herein may include a step of screening a subject for one or more mutations in genes known to be associated with hearing loss or vestibular dysfunction prior to treatment with or administration of the auricular dosage forms described herein. A subject can be screened for a genetic mutation using standard methods known to those of skill in the art (e.g., genetic testing). The methods described herein may also include a step of assessing hearing and/or vestibular function in a subject prior to treatment with or administration of the auricular dosage forms described herein. Hearing can be assessed using standard tests, such as audiometry, auditory brainstem response (ABR), electrochocleography (ECOG), and otoacoustic emissions.

Vestibular function may be assessed using standard tests, such as eye movement testing (e.g., electronystagmogram (ENG) or videonystagmogram (VNG)), posturography, rotary-chair testing, ECOG, vestibular evoked myogenic potentials (VEMP), and specialized clinical balance tests, such as those described in Mancini and Horak, Eur J Phys Rehabil Med, 46:239 (2010). These tests can also be used to assess hearing and/or vestibular function in a subject after treatment with or administration of the auricular dosage forms described herein. The auricular dosage forms and methods described herein may also be administered as a preventative treatment to patients at risk of developing hearing loss and/or vestibular dysfunction, e.g., patients who have a family history of hearing loss or vestibular dysfunction (e.g., inherited hearing loss or vestibular dysfunction), patients carrying a genetic mutation associated with hearing loss or vestibular dysfunction who do not yet exhibit hearing impairment or vestibular dysfunction or patients exposed to risk factors for acquired hearing loss (e.g., acoustic trauma, disease or infection, head trauma, ototoxic drugs, or aging) or vestibular dysfunction (e.g., disease or infection, head trauma, ototoxic drugs, or aging).

The auricular dosage forms and methods described herein can be used to promote or induce hair cell regeneration in a subject (e.g., cochlear and/or vestibular hair cell regeneration) and/or SGN regeneration in a subject. Subjects that may benefit from auricular dosage forms that promote or induce hair cell regeneration and/or SGN regeneration include subjects suffering from hearing loss or vestibular dysfunction as a result of loss of hair cells and/or SGNs (e.g., loss of hair cells and/or SGNs related to trauma (e.g., acoustic trauma or head trauma), disease or infection, ototoxic drugs, or aging), and subjects with abnormal hair cells and/or SGNs (e.g., hair cells and/or SGNs that do not function properly when compared to normal hair cells), damaged hair cells and/or SGNs (e.g., hair cell and/or SGN damage related to trauma (e.g., acoustic trauma or head trauma), disease or infection, ototoxic drugs, or aging), or reduced hair cell and/or SGN numbers due to genetic mutations or congenital abnormalities. The auricular dosage forms and methods described herein can also be used to promote or increase hair cell survival and/or SGN survival (e.g., increase survival of damaged hair cells and/or SGNs, promote repair of damaged hair cells and/or SGNs, or preserve hair cells and/or SGNs in a subject at risk of loss of hair cells and/or SGNs (e.g., loss of hair cells and/or SGNs due to age, exposure to loud noise, disease or infection, head trauma, or ototoxic drugs)).

The auricular dosage forms and methods described herein can also be used to prevent or reduce hair cell and/or SGN damage or death (e.g., cochlear hair cell and/or vestibular hair cell damage or death and/or SGN damage or death). In some embodiments, the methods prevent or reduce ototoxic drug- induced hair cell and/or SGN damage or death. In some embodiments, the methods prevent or reduce ototoxic drug-induced hair cell and/or SGN damage or death in subjects who have been treated with ototoxic drugs, or who are currently undergoing or soon to begin treatment with ototoxic drugs. Ototoxic drugs are toxic to the cells of the inner ear (e.g., hair cells and SGNs), and can cause sensorineural hearing loss, vestibular dysfunction (e.g., vertigo, dizziness, or imbalance), tinnitus, or a combination of these symptoms. Drugs that have been found to be ototoxic include aminoglycoside antibiotics (e.g., gentamycin, neomycin, streptomycin, tobramycin, kanamycin, vancomycin, and amikacin), viomycin, antineoplastic drugs (e.g., platinum-containing chemotherapeutic agents, such as cisplatin, carboplatin, and oxaliplatin), loop diuretics (e.g., ethacrynic acid and furosemide), salicylates (e.g., aspirin, particularly at high doses), and quinine. In some embodiments, the methods described herein prevent or reduce hair cell and/or SGN damage or death (e.g., cochlear hair cell and/or vestibular hair cell damage or death and/or SGN damage or death) related to acoustic trauma, disease or infection, head trauma, or aging.

Particular embodiments of the auricular dosage forms that can be used to treat subjects having or at risk of developing sensorineural hearing loss, tinnitus, deafness, auditory neuropathy, and/or vestibular dysfunction, promote or induce hair cell and/or SGN regeneration, or prevent or reduce hair cell and/or SGN damage or death (e.g., ototoxic drug-induced hair cell and/or SGN damage or death, noise-induced hair cell and/or SGN damage or death, or age-related hair cell and/or SGN damage or death), or promote hair cell regeneration include those in which the therapeutic agent is a neurotrophin, an immunomodulating agent, an aural pressure modulating agent, a corticosteroid, an antimicrobial agent, an antagonist of truncated TrkC or truncated TrkB, a non-natural TrkB or TrkC agonist, a TrkB receptor agonist antibody, a TrkB receptor agonist compound, a TrkC receptor agonist antibody, a TrkC receptor agonist compound, a neuroprotection agent, an Atohl modulator (e.g., an Atohl polypeptide or a nucleic acid vector engineered to express Atohl , e.g., human Atohl (Hathl )), a WNT modulator or an anti platinum chemoprotectant agent. For example, auricular dosage forms that are particularly suited for these indications are those in which the therapeutic agent is a neurotrophin selected from NT-3, NGF, BDNF, CNTF, GDNF, NT-4, FGF, IGF, EGF, PGF, MANF, CDNF, a pan-neurotrophin (e.g., PNT-1), a chimeric neurotrophin (e.g., an NGF/BDNF chimera), or a combination thereof. In another example, auricular dosage forms that are suited for preventing or reducing ototoxic-drug induced hair cell and/or SGN damage or death, in particular, for preventing or mitigating platinum-induced ototoxicity, are those in which the therapeutic agent is an anti-platinum chemoprotectant agent (e.g., an alkaline or ammonium thiosulfate salt or a solvate thereof, an alkaline diethyldithiocarbamate salt, amifostine, methionine, N- acetylcysteine, cysteine, 2-aminoethanethiol, glutathione (GSH) or a C1-C6 alkyl ester thereof, lysine, histidine, arginine, ethylene diamine tetraacetic acid, dimercaprol, dimercaptosuccinic acid, dimercapto- propane sulfonate salt, penicillamine, a-lipoic acid, or fursultiamine, or a salt thereof, such as sodium thiosulfate or N-acetylcysteine).

The auricular dosage forms described herein are administered in an amount sufficient to improve hearing, improve vestibular function (e.g., improve balance or reduce dizziness or vertigo), treat, prevent, reduce or slow the development of tinnitus, treat, prevent, reduce, or delay the development of hearing loss, slow the progression of hearing loss, treat, prevent, reduce, or delay the development of vestibular dysfunction, slow the progression of vestibular dysfunction, prevent or reduce hair cell damage (e.g., hair cell damage related to acoustic trauma, head trauma, ototoxic drugs, disease or infection, or aging), prevent, slow, or reduce hair cell death (e.g., ototoxic drug-induced hair cell death, noise-related hair cell death, age-related hair cell death, disease or infection-related hair cell death, or head trauma-related hair cell death), promote or increase hair cell development, increase hair cell numbers (e.g., promote or induce hair cell regeneration), promote or increase hair cell survival, improve hair cell function, prevent or reduce SGN damage, prevent, slow, or reduce SGN death (e.g., ototoxic drug-induced SGN death or age-related SGN death), promote or increase SGN development, increase SGN numbers (e.g., promote or induce SGN regeneration), increase or promote SGN survival, promote SGN repair, improve SGN function, preserve ribbon synapses, promote or increase ribbon synapse formation, maintain the connections (e.g., synaptic connections) between hair cells and SGNs, or increase or restore the connections (e.g., synaptic connections) between hair cells and SGNs. Flearing may be evaluated using standard hearing tests (e.g., audiometry, ABR, electrochocleography (ECOG), and otoacoustic emissions) and may be improved by 5% or more (e.g., 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 125%, 150%, 200% or more) compared to hearing measurements obtained prior to treatment. Vestibular function may be evaluated using standard tests for balance and vertigo (e.g., eye movement testing (e.g., ENG or VNG), posturography, rotary-chair testing, ECOG, VEMP, and specialized clinical balance tests) and may be improved by 5% or more (e.g., 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 125%, 150%, 200% or more) compared to measurements obtained prior to treatment. In some embodiments, the auricular dosage forms are administered in an amount sufficient to improve the subject’s ability to understand speech. The auricular dosage forms described herein may also be administered in an amount sufficient to slow or prevent the development or progression of sensorineural hearing loss and/or vestibular dysfunction (e.g., in subjects who carry a genetic mutation associated with hearing loss or vestibular dysfunction, who have a family history of hearing loss or vestibular dysfunction (e.g., hereditary hearing loss or vestibular dysfunction), or who have been exposed to risk factors associated with hearing loss or vestibular dysfunction (e.g., ototoxic drugs, head trauma, disease or infection, or acoustic trauma) but do not exhibit hearing impairment or vestibular dysfunction (e.g., vertigo, dizziness, or imbalance), or in subjects exhibiting mild to moderate hearing loss or vestibular dysfunction). Hair cell numbers, hair cell function, SGN numbers, or SGN function may be evaluated indirectly based on hearing tests or tests of vestibular function, and may be increased by 5% or more (e.g., 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 125%, 150%, 200% or more) compared to hair cell numbers, hair cell function, SGN numbers, or SGN function prior to administration of the auricular dosage forms described herein. Hair cell damage or death and/or SGN damage or death may be reduced by 5% or more (e.g., 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%, 125%, 150%, 200% or more) compared to hair cell damage or death and/or SGN damage or death typically observed in untreated subjects, and can be evaluated indirectly based on standard hearing tests. These effects may occur, for example, within 1 week, 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 7 weeks, 8 weeks, 9 weeks, 10 weeks, 15 weeks, 20 weeks, 25 weeks, or more, following administration of the auricular dosage forms described herein. The patient may be evaluated 1 month, 2 months, 3 months, 4 months, 5 months, 6 months or more following administration of the auricular dosage form depending on the dose and route of administration used for treatment. Depending on the outcome of the evaluation, the patient may receive additional treatments.

Routes of Administration and Dosing

Auricular dosage forms may be administered once, or more than once (e.g., once annually, twice annually, three times annually, bi-monthly, or monthly). Auricular dosage forms are administered auricularly. In particular embodiments, the auricular dosage form is administered intratympanically or transtympanically.

In the methods of the invention, typically, a needle is used to pierce the tympanic membrane to instill drug into the middle ear space or traverse an existing PE tube or perforation of the ear drum to instill drug. A separate ventilation hole in the tympanic membrane may or may not be created to allow air to escape the middle ear space. The instilled drug may then target middle ear structures, cells or be designed to enter the inner ear via the round and oval membranes to affect specific targets. This may be accomplished, e.g., by instilling drug through the round window membrane, the oval window, a cochleostomy, or labrinthotomy approach. These surgical procedures may be accomplished by raising a tympanomeatal flap (lifting up the ear drum) and exposing the round window, stapes/oval window and promontory. A stapedotomy hole may be created in the footplate and the drug instilled into the vestibule by pump, injection, or some other method. Alternatively, the bony lip of the round window (RW) is removed (typically by drill) to expose the RW. The RW may then be pierced with a needle and the drug infused or the RW may be fenestrated and the drug instilled directly through the fenestration. Finally, an entirely separate entrance hole to the cochlea may be opened by drilling a cochleostomy hole into the cochlea and drug instilled.

Alternatively, rather than raising a tympanomeatal flap, a mastoidectomy may be performed and the facial recess opened to provide direct access to the oval and round windows as well as the promontory and the semicircular canals. Via this approach, all three sites can be used as just described. In addition, the labyrinth may be opened, much like a cochleostomy, for the instillation of drug. To dissipate fluid/pressure buildup in the inner ear, a separate opening into the RW or OW may be created to allow for excess perilymph to leak out.

In some embodiments, the amount of the auricular dosage form administered to the subject is, or the auricular unit dosage form has a volume of, at least 0.05 ml_ (e.g., at least 0.1 ml_, at least 0.2 ml_, at least 0.3 ml_, at least 0.4 ml_, at least 0.5 ml_, at least 0.6 ml_, at least 0.7 ml_, at least 0.8 ml_, at least 0.9 ml_, or at least 1 ml_; e.g., 1 .1 ml_ or less, 1 ml_ or less, 0.9 ml_ or less, 0.8 ml_ or less, 0.7 ml_ or less, 0.6 ml_ or less, 0.5 ml_ or less, 0.4 ml_ or less, 0.3 ml_ or less, or 0.2 ml_ or less; e.g., 0.05 ml_ to 1 .1 ml_, 0.1 ml_ to 1 .1 ml_, 0.2 ml_ to 1 .1 ml_, 0.3 ml_ to 1 .1 ml_, 0.4 ml_ to 1 .1 ml_, 0.5 ml_ to 1 .1 ml_, 0.6 ml_ to 1 .1 ml_, 0.7 ml_ to 1 .1 ml_, 0.8 ml_ to 1 .1 ml_, 0.9 ml_ to 1 .1 ml_, 1 ml_ to 1 .1 ml_, 0.05 ml_ to 1 ml_, 0.1 ml_ to 1 ml_, 0.2 ml_ to 1 ml_, 0.3 ml_ to 1 ml_, 0.4 ml_ to 1 ml_, 0.5 ml_ to 1 ml_, 0.6 ml_ to 1 ml_, 0.7 ml_ to 1 ml_, 0.8 ml_ to 1 ml_, 0.9 ml_ to 1 ml_, 0.05 ml_ to 0.9 ml_, 0.1 ml_ to 0.9 ml_, 0.2 ml_ to 0.9 ml_, 0.3 ml_ to 0.9 ml_, 0.4 ml_ to 0.9 ml_, 0.5 ml_ to 0.9 ml_, 0.6 ml_ to 0.9 ml_, 0.7 ml_ to 0.9 ml_, 0.8 ml_ to 0.9 ml_, 0.05 ml_ to 0.8 ml_, 0.1 ml_ to 0.8 ml_, 0.2 ml_ to 0.8 ml_, 0.3 mL to 0.8 ml_, 0.4 mL to 0.8 ml_, 0.5 mL to 0.8 ml_, 0.6 mL to 0.8 mL, 0.7 mL to 0.8 mL, 0.05 mL to 0.7 mL, 0.1 mL to 0.7 mL, 0.2 mL to 0.7 mL, 0.3 mL to 0.7 mL, 0.4 mL to 0.7 mL, 0.5 mL to 0.7 mL, 0.6 mL to 0.7 mL, 0.05 mL to 0.6 mL, 0.1 mL to 0.6 mL, 0.2 mL to 0.6 mL, 0.3 mL to 0.6 mL, 0.4 mL to 0.6 mL, 0.5 mL to 0.6 mL, 0.05 mL to 0.5 mL, 0.1 mL to 0.5 mL, 0.2 mL to 0.5 mL, 0.3 mL to 0.5 mL, 0.4 mL to 0.5 mL, 0.05 mL to 0.4 mL, 0.1 mL to 0.4 mL, 0.2 mL to 0.4 mL,

0.3 mL to 0.4 mL, 0.05 mL to 0.3 mL, 0.1 mL to 0.3 mL, or 0.2 mL to 0.3 mL).

In some embodiments, the auricular dosage form is configured to control the release profile of the therapeutic agent. In general, the release profile of the therapeutic agent is controlled in part by the physical and chemical interactions of the agent with the other components of the auricular dosage form, e.g., pH, solubility, hydration, complexation, and diffusivity. The auricular dosage form may allow for the immediate release of the therapeutic agent. In some embodiments, the auricular dosage form may allow for sustained release of the therapeutic agent. For example, the release of the therapeutic agent may be sustained from about 1 day to about 6 weeks, or more (e.g., for about 1 day, about 2 days, about 3 days, about 4 days, about 5 days, about 6 days, about 7 days, about 8 days, about 9 days, about 10 days, about 11 days, about 12 days, about 13 days, 14 days, 21 days, 28 days, 35 days, 42 days, 48 days, or more). The sustained release of the therapeutic agent may occur in a continuous matter, pulsatile manner, or a combination of both. In addition, the auricular dosage form may be configured for both an immediate release and controlled release of the therapeutic agent, and may further be dependent on the environmental or physiological conditions of the administration.

Other Components

The auricular dosage forms described herein may contain pharmaceutically acceptable diluents, carriers, and/or excipients. For example, the auricular dosage forms described herein may contain, e.g., liquid solvents, buffering agents, viscosity agents, and/or coloring agents. Certain excipients may perform multiple roles. For example, a liquid solvent, in addition to its function as a carrier, may be used as a buffering agent. Such solvents are known in the art, e.g., salines (e.g., hypertonic saline, hypotonic saline, isotonic saline, or phosphate-buffered saline) and artificial perilymph.

Liquid solvents that may be used in conjunction with the auricular dosage forms described herein include water, mineral oil, salines (e.g., hypertonic saline, hypotonic saline, isotonic saline, or phosphate- buffered saline), artificial perilymph, and tris buffer. Artificial perilymph is an aqueous solution containing NaCI (120-130 mM), KCI (3.5 mM), CaCI₂ (1 .3-1 .5 mM), MgCI₂ (1 .2 mM), glucose (5.0-11 mM), and buffering agents (e.g., NaHC03 (25 mM) and NaH₂P04 (0.75 mM), or HEPES (20 mM) and NaOH (adjusted to pH of about 7.5)).

Buffering agents may be used to adjust the pH of an auricular dosage form (e.g., a pharmaceutical dosage form) of the invention a substantially neutral pH level. Examples of buffering agents that may be used in the auricular dosage forms and methods described herein are known in the art, and include, without limitation, phosphate buffers and Good’s buffers (e.g., tris, MES, MOPS, TES, HEPES, HEPPS, tricine, and bicine). In addition to regulating pH, buffering agents may be used to control the osmolarity of the auricular dosage form.

Viscosity agents can be used to increase or decrease the dynamic viscosity of the auricular dosage form prior to administration or to control the dynamic viscosity post administration. Viscosity agents may further control the release profile of the compound of the auricular dosage form. Examples of viscosity agents that may be used in the auricular dosage forms and methods described herein are known in the art and include, without limitation, sodium stearate, bladderwrack, bentonite, eratonia, chondrus, dextrose, furcellaran, Ghatti gum, hectorite, lactose, sucrose, sucralose, maltodextrin, mannitol, sorbitol, honey, cellulose and its derivatives (e.g., ethyl cellulose, ethylhydroxyethyl cellulose, ethylmethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxyethylmethyl cellulose, hydroxypropyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl-cellulose (HPMC), sodium carboxymethyl-cellulose (CMC)), pectin, chondroitin sulfate, or a combination thereof.

The following examples are meant to illustrate the invention. They are not meant to limit the invention in any way.

EXAMPLES

The following examples are put forth so as to provide those of ordinary skill in the art with a description of how the auricular dosage forms and methods described herein may be used, made, and evaluated, and are intended to be purely exemplary of the invention and are not intended to limit the scope of what the inventors regards as their invention.

Example 1. Auricular dosage forms containing sodium thiosulfate and glycerol

Gel 1 (1M, 1% (w/v) hyaluronan)

Hyaluronan (30.68 mg; Pharma Grade 80, Kikkoman Biochemifa company) was added to 3 mL of distilled water. The resulting mixture was stirred at 4 C for 30 min. Sodium thiosulfate pentahydrate (744.90 mg) was added to the solution. The pH was adjusted to pH 7.21 by addition of NaOH (0.1 M, 2 pL). The resulting solution was filtered through 0.22 pm Millex-GV sterile filter with 1820 mOsmol/kg. Gel 2 (1M STS and glycerol (10%) in 1 % (w/v) hyaluronan)

Glycerol (300.45mg) was placed in a vial, and distilled water was added to 3 mL. Hyaluronan (30.86 mg; Pharma Grade 80, Kikkoman Biochemifa company) was added to the solution. The resulting mixture was stirred at 4 C for 60 min. Sodium thiosulfate pentahydrate (744.82 mg) was added to the solution. The mixture was stirred for 20 min at 4 C. The pH was adjusted to pH 6.93 by addition of NaOH (0.1 M, 1 mI_). The resulting solution was filtered through 0.22 pm Millex-GV sterile filter.

Gels 3, 4, 5, 6, 7, and 8 were prepared in a similar manner as Gel 2.

Gel 9

Poloxamer 407 (749.23mg) was added to PBS (1 x, 3.25 mL), and the mixture was stirred at 4 C for 40 min. Glycerol (798.24 mg) was added. Ebselen (10.51 mg) was placed in a vial, and 2.102 mL of the vehicle was added to ebselen. The mixture was stirred for 30 min at 4 C.

Gel 11

Glycerol (795.42 mg) was placed in a vial. Water (2mL) was added to the vial, and the mixture was stirred for 1 min. Hyaluronan (20.46 mg; Pharma Grade 80, Kikkoman Biochemifa company) was added to the vial, and the resulting mixture was stirred for 30 min in an ice bath. pH was measured as 7.24. The resulting solution was filtered through 0.22 pm Millex-GV sterile filter.

Example 2. Pharmacokinetics and Auditory Brainstem Response

Pre-operation:

Male guinea pigs weighing 200-300 g of approximately 5-7 weeks of age served as subjects (N = 5 per group). Prior to any procedures, animals were anesthetized using zolazepam hydrochloride (Zoletil 50; 20 mg/kg) 10 minutes before surgery via the intramuscular route.

Transtympanic injection:

1 . The hair was shaved around the left ear using an electric razor, and the skin was then cleaned using 75% ethanol.

2. A sterile surgical field was established and a sterile draping cloth was applied.

3. A small hole was created over the upper left side of the tympanic membrane with a metal syringe.

4. 50 pL of the auricular dosage form was delivered through the right side of tympanic membrane using a sterile glass Hamilton syringe with 25-26 G blunt needle. The solution was injected at a set rate.

5. After the injection, the position of the animal was unchanged, and the animal was kept lying on its side for more than 30 min.

Intratympanic injection: 1 . Under microscopic magnification, sharp scissors were used to create a 0.5-1 .5 cm postauricular skin incision, approximately 6-8 mm caudal to the auriculo-cephalic crease. Care was exercised to avoid cutting deeply to preserve underlying vascular structures.

2. Careful blunt dissection through the subcutaneous fat layer, muscles and tissues was performed with forceps. The cleidomastoideus muscle body was gently retracted until the shiny dome of the tympanic bulla periosteum came into view. At the caudal aspect of the bulla, the insertion of a deeper cervical muscle, the sternomastoideus came into view. The facial nerve, which becomes visible at the dorsal and rostral aspect of the bulla dome, was preserved during the operation.

3. A self-retaining retractor was placed prior to creating a small hole (0.5mm diameter) either with a drilling in the posterior part of the bulla. The bulla bone was uncapped in a dorsal and caudal direction using a pair of jeweler's tip forceps. The bone was removed in a piecemeal fashion under high magnification. Care was exercised not to puncture the stapedial artery, which lies directly beneath the bulla cap, as bleeding from this artery may compromise the procedure. The amount of bone removed was kept to a minimum to prevent excessive fluid entry to the middle ear while still allowing excellent visualization and access to the round window niche.

4. 10 or 90 mI_ of a gel auricular dosage form was delivered to the round window niche using a sterile glass Hamilton syringe with 25-26 G blunt needle.

5. The delivered agent was allowed to rest within the round window niche for up to 30 min. The small hole was covered with muscular tissue and tissue glue.

6 . The incision was closed with sutures (4-0 non-absorbable monofilament or 5-0 non-absorbable nylon) and tissue glue or wound clips. The entire procedure took approximately 3-5 minutes depending on agent specifications.

7. During the procedure and until recovery, animals were placed on a temperature controlled (38 °C) heating pad until consciousness was regained, at which time they were returned to the home-cage.

ABR/hearing testing

1 . Prior to ABR recording the tympanic membrane was inspected for otitis media using a surgical microscope. Animals with otitis media were excluded from the analysis.

2. A TDT RZ6 system was used to record the auditory brainstem response (ABR).

3. Animals were anaesthetized with zoletil (20 mg/kg, I.M.) and placed in a soundproof chamber.

4. Three stainless needle recording electrodes were inserted just under the skin and connected to the appropriate input on the PA4LI low impedance headstage: Channel 1 : Ipsilateral ear (same side as stimulus delivery); Reference: contralateral ear; Ground: Vertex (base of skull).

5. A computer-controlled TDT RZ6 System was used to generate the auditory pure tone and power amplified before being fed to a closed-field speaker to deliver sound stimuli. The same pure tone stimuli was repeated 512 times, the sound pressure levels were increased in a step of 10 dB SPL (5 dB around threshold) from 20 dB SPL to 90 dB SPL after every 512 repeated trials.

6. The lowest sound level which induced a brainstem response was regarded as the threshold. Hearing threshold was measured at 4, 24, and 32 kHz. ABR recording was performed before surgery or dosing and the 7^th and 14^th day after auricular dosage form dosing. The ABR was recorded first from the left ear and then from the right ear. Sampling collection:

Blood collection:

1 . Without preinflating in the euthanasia box, the guinea pig was placed in a box, and 100% carbon dioxide was introduced to cause the animal unconsciousness and to reduce animal suffering. Carbon dioxide flow was maintained for a minimum of 1 minute after the breath had stopped. The guinea pig was removed from the euthanasia box after death was confirmed.

2. Blood was collected immediately after euthanasia.

3. After the operator fixed the animal's back position, the needle was inserted at the front of the sternal ridge at 4-6 or slightly forward.

4. The needle was pulled back, and the blood was returned.

5. Volume: for each blood collection, ca. 1 ml_ of blood was collected.

CSF collection:

CSF was collected after euthanasia. A 0.5^*20 intravenous infusion needle was slowly lowered from 90° to the foramen magnum. The needle reached a distance of 4.5-5 mm under the skin, and 50- 200 mI of clear tissue fluid were withdrawn.

Perilymph collection:

1 . After euthanasia, the animal was stripped of excess skin and muscle tissue to obtain a complete auditory bulla, and the bulla wall was cut with small forceps to expose the cochlea. The basal turn of bulla was cleaned using small cotton ball.

2. The cochlear bottom circle and the round window were coated with bio glue. After drying, a unique microhole was hand drilled in the top circle of the cochlea.

3. A 2 mI_ volume of perilymph was then collected using a microcapillary inserted into the cochlear scala tympani.

4. Perilymph samples were stored at -80 ^SC until analysis.

The results of the pharmacokinetic and ABR studies are shown in FIGS. 1 and 2 and in Table 5.

Table 5

In Table 5, HA is hyaluronan. Terminal T1/2 was measured in hours.

Example 3. Delivery of a therapeutic agent across the round window membrane of a human patient

Using the auricular dosage forms and methods described herein, a physician can deliver a therapeutic agent into the inner ear of a subject (e.g., a mammalian subject, such as a human). For example, a physician may administer an auricular dosage form containing glycerol to a human patient so as to effectuate the passage of a therapeutic agent into the inner ear of the patient (e.g., through the round window membrane). The auricular dosage form may be administered so as to treat or mitigate one or more of a variety of otic disorders, such as ceruminosis or ceruminosis associated with an otic disease or condition, ear pruritus, otitis externa, otalgia, tinnitus, vestibular dysfunction (e.g., vertigo, dizziness, or loss of balance), ear fullness, hearing loss, Meniere's disease, sensorineural hearing loss (e.g., noise- induced hearing loss, age-related hearing loss (presbycusis), ototoxic drug-induced hearing loss, hearing loss related to head trauma, hearing loss related to infection), autoimmune ear disease, ototoxicity, excitotoxicity, hidden hearing loss, cochlear synaptopathy, endolymphatic hydrops, labyrinthitis, Ramsay Hunt's Syndrome, vestibular neuronitis, or microvascular compression syndrome, hyperacusis, presbystasis, central auditory processing disorder, auditory neuropathy, improvement of cochlea implant performance, or a combination thereof.

Upon determining that the patient has one or more of the above conditions and/or is a candidate for therapy, the physician may administer the auricular dosage form to the patient by way of one or more routes of administration described herein. For example, the physician may administer the auricular dosage forms to the patient auricularly, e.g., by intratympanic or transtympanic administration (e.g., injection). The physician may determine the optimal quantity of the auricular dosage form to administer to the patient. For example, the physician may choose to administer at least 0.05 ml_ of the auricular dosage form to the round window of the subject. Exemplary amounts of the auricular dosage form that may be administered to the subject are, without limitation, at least 0.05 ml_ (e.g., at least 0.1 ml_, at least 0.2 ml_, at least 0.3 ml_, at least 0.4 ml_, at least 0.5 ml_, at least 0.6 ml_, at least 0.7 ml_, at least 0.8 ml_, at least 0.9 ml_, or at least 1 ml_; e.g., 1 .1 ml_ or less, 1 ml_ or less, 0.9 ml_ or less, 0.8 ml_ or less, 0.7 ml_ or less, 0.6 ml_ or less, 0.5 ml_ or less, 0.4 ml_ or less, 0.3 ml_ or less, or 0.2 ml_ or less; e.g., 0.05 ml_ to 1 .1 ml_, 0.1 ml_ to 1 .1 ml_, 0.2 ml_ to 1 .1 ml_, 0.3 ml_ to 1 .1 ml_, 0.4 ml_ to 1 .1 ml_, 0.5 ml_ to 1 .1 ml_, 0.6 ml_ to 1 .1 ml_, 0.7 ml_ to 1 .1 ml_, 0.8 ml_ to 1 .1 ml_, 0.9 ml_ to 1 .1 ml_, 1 ml_ to 1 .1 ml_, 0.05 ml_ to 1 ml_,

0.1 ml_ to 1 ml_, 0.2 ml_ to 1 ml_, 0.3 ml_ to 1 ml_, 0.4 ml_ to 1 ml_, 0.5 ml_ to 1 ml_, 0.6 ml_ to 1 ml_, 0.7 ml_ to 1 ml_, 0.8 ml_ to 1 ml_, 0.9 ml_ to 1 ml_, 0.05 ml_ to 0.9 ml_, 0.1 ml_ to 0.9 ml_, 0.2 ml_ to 0.9 ml_, 0.3 ml_ to 0.9 ml_, 0.4 ml_ to 0.9 ml_, 0.5 ml_ to 0.9 ml_, 0.6 ml_ to 0.9 ml_, 0.7 ml_ to 0.9 ml_, 0.8 ml_ to 0.9 ml_,

0.05 ml_ to 0.8 ml_, 0.1 ml_ to 0.8 ml_, 0.2 ml_ to 0.8 ml_, 0.3 ml_ to 0.8 ml_, 0.4 ml_ to 0.8 ml_, 0.5 ml_ to 0.8 ml_, 0.6 ml_ to 0.8 ml_, 0.7 ml_ to 0.8 ml_, 0.05 ml_ to 0.7 ml_, 0.1 ml_ to 0.7 ml_, 0.2 ml_ to 0.7 ml_, 0.3 ml_ to 0.7 ml_, 0.4 ml_ to 0.7 ml_, 0.5 ml_ to 0.7 ml_, 0.6 ml_ to 0.7 ml_, 0.05 ml_ to 0.6 ml_, 0.1 ml_ to 0.6 ml_,

0.2 ml_ to 0.6 ml_, 0.3 ml_ to 0.6 ml_, 0.4 ml_ to 0.6 ml_, 0.5 ml_ to 0.6 ml_, 0.05 ml_ to 0.5 ml_, 0.1 ml_ to 0.5 mL, 0.2 mL to 0.5 mL, 0.3 mL to 0.5 mL, 0.4 mL to 0.5 mL, 0.05 mL to 0.4 mL, 0.1 mL to 0.4 mL, 0.2 mL to 0.4 mL, 0.3 mL to 0.4 mL, 0.05 mL to 0.3 mL, 0.1 mL to 0.3 mL, or 0.2 mL to 0.3 mL).

After a period of time, such as from about 1 day to about 6 weeks, or more, the physician may conduct an analysis to determine whether the therapeutic agent is still present in vivo at an effective level. The physician may obtain a sample from the patient, such as a blood sample or perilymph sample, and may determine whether the subject is a candidate for a subsequent administration of the therapeutic agent based, for example, on the concentration of the therapeutic agent remaining in the sample and the time from the initial administration at which the sample was obtained.

Example 4. Delivery of a neurotrophin across the round window membrane of a human patient to prevent or reduce sensory hair cell damage or death

A physician may administer an auricular dosage form containing glycerol to a human patient in order to treat, prevent, or reduce sensory hair cell damage or death in the subject. For example, a neurotrophin (e.g., neurotrophin-3 (NT-3), nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), glial cell-line derived neurotrophic factor (GDNF), neurotrophin-4 (NT-4), fibroblast growth factor (FGF), insulin-like growth factor (IGF), epidermal growth factor (EGF), platelet-derived growth factor (PGF), mesencephalic astrocyte-derived neurotrophic factor (MANF), cerebral dopamine neurotrophic factor (CDNF), a pan-neurotrophic factor (e.g., PNT-1 ), a chimeric neurotrophin (e.g., a NGF/BDNF chimera), or combinations thereof) may be admixed with glycerol, optionally in combination with a gelling agent (e.g., hyaluronan), and administered to the patient so as to treat, prevent, or reduce sensory hair cell damage or death. The resulting auricular dosage form may be administered to the patient by way, for example, of local administration, e.g., by intratympanic or transtympanic administration.

The physician may determine the optimal quantity of the auricular dosage form to administer to the patient. For example, the physician may choose to administer at least 0.05 mL of the auricular dosage form to the round window of the subject. Exemplary amounts of the auricular dosage form that may be administered to the subject are, without limitation, at least 0.1 mL, at least 0.2 mL, at least 0.3 mL, at least 0.4 mL, at least 0.5 mL, at least 0.6 mL, at least 0.7 mL, at least 0.8 mL, at least 0.9 mL, or at least 1 mL; e.g., 1 .1 mL or less, 1 mL or less, 0.9 mL or less, 0.8 mL or less, 0.7 mL or less, 0.6 mL or less, 0.5 mL or less, 0.4 mL or less, 0.3 mL or less, or 0.2 mL or less; e.g., 0.05 mL to 1 .1 mL, 0.1 mL to 1 .1 mL, 0.2 mL to 1 .1 mL, 0.3 mL to 1 .1 mL, 0.4 mL to 1 .1 mL, 0.5 mL to 1 .1 mL, 0.6 mL to 1 .1 mL, 0.7 mL to 1 .1 mL, 0.8 mL to 1 .1 mL, 0.9 mL to 1 .1 mL, 1 mL to 1 .1 mL, 0.05 mL to 1 mL, 0.1 mL to 1 mL, 0.2 mL to 1 mL, 0.3 mL to 1 mL, 0.4 mL to 1 mL, 0.5 mL to 1 mL, 0.6 mL to 1 mL, 0.7 mL to 1 mL, 0.8 mL to 1 mL, 0.9 mL to 1 mL, 0.05 mL to 0.9 mL, 0.1 mL to 0.9 mL, 0.2 mL to 0.9 mL, 0.3 mL to 0.9 mL, 0.4 mL to 0.9 mL, 0.5 mL to 0.9 mL, 0.6 mL to 0.9 mL, 0.7 mL to 0.9 mL, 0.8 mL to 0.9 mL, 0.05 mL to 0.8 mL, 0.1 mL to 0.8 mL, 0.2 mL to 0.8 mL, 0.3 mL to 0.8 mL, 0.4 mL to 0.8 mL, 0.5 mL to 0.8 mL, 0.6 mL to 0.8 mL, 0.7 mL to 0.8 mL, 0.05 mL to 0.7 mL, 0.1 mL to 0.7 mL, 0.2 mL to 0.7 mL, 0.3 mL to 0.7 mL, 0.4 mL to 0.7 mL, 0.5 mL to 0.7 mL, 0.6 mL to 0.7 mL, 0.05 mL to 0.6 mL, 0.1 mL to 0.6 mL, 0.2 mL to 0.6 mL, 0.3 mL to 0.6 mL, 0.4 mL to 0.6 mL, 0.5 mL to 0.6 mL, 0.05 mL to 0.5 mL, 0.1 mL to 0.5 mL, 0.2 mL to 0.5 mL,

0.3 mL to 0.5 mL, 0.4 mL to 0.5 mL, 0.05 mL to 0.4 mL, 0.1 mL to 0.4 mL, 0.2 mL to 0.4 mL, 0.3 mL to 0.4 mL, 0.05 mL to 0.3 mL, 0.1 mL to 0.3 mL, or 0.2 mL to 0.3 mL. After a period of time, such as from about 1 day to about 6 weeks, or more, the physician may conduct an analysis to determine whether the therapeutic agent is still present in vivo at an effective level. The physician may obtain a sample from the patient, such as a blood sample or perilymph sample, and may determine whether the subject is a candidate for a subsequent administration of the therapeutic agent based, for example, on the concentration of the therapeutic agent remaining in the sample and the time from the initial administration at which the sample was obtained.

Example 5. Delivery of an anti-platinum chemoprotectant agent across the round window membrane of a human patient to mitigate platinum-induced ototoxicity

A physician may administer an auricular dosage form containing glycerol to a human patient in order to treat, prevent, or reduce sensory hair cell damage or death in the subject. For example, a thiosulfate salt or a pharmaceutically acceptable solvate thereof may be admixed with glycerol, optionally in combination with a gelling agent (e.g., hyaluronan), and administered to the patient so as to treat, prevent, or reduce sensory hair cell damage or death. The resulting auricular dosage form may be administered to the patient by way, for example, of local administration, e.g., by intratympanic or transtympanic administration.

The physician may determine the optimal quantity of the auricular dosage form to administer to the patient. For example, the physician may choose to administer at least 0.05 ml_ of the auricular dosage form to the round window of the subject. Exemplary amounts of the auricular dosage form that may be administered to the subject are, without limitation, at least 0.1 ml_, at least 0.2 ml_, at least 0.3 ml_, at least 0.4 ml_, at least 0.5 ml_, at least 0.6 ml_, at least 0.7 ml_, at least 0.8 ml_, at least 0.9 ml_, or at least 1 ml_; e.g., 1 .1 ml_ or less, 1 ml_ or less, 0.9 ml_ or less, 0.8 ml_ or less, 0.7 ml_ or less, 0.6 ml_ or less, 0.5 ml_ or less, 0.4 ml_ or less, 0.3 ml_ or less, or 0.2 ml_ or less; e.g., 0.05 ml_ to 1 .1 ml_, 0.1 ml_ to 1 .1 ml_, 0.2 ml_ to 1 .1 ml_, 0.3 ml_ to 1 .1 ml_, 0.4 ml_ to 1 .1 ml_, 0.5 ml_ to 1 .1 ml_, 0.6 ml_ to 1 .1 ml_, 0.7 ml_ to 1 .1 ml_, 0.8 ml_ to 1 .1 ml_, 0.9 ml_ to 1 .1 ml_, 1 ml_ to 1 .1 ml_, 0.05 ml_ to 1 ml_, 0.1 ml_ to 1 ml_, 0.2 ml_ to 1 ml_, 0.3 ml_ to 1 ml_, 0.4 ml_ to 1 ml_, 0.5 ml_ to 1 ml_, 0.6 ml_ to 1 ml_, 0.7 ml_ to 1 ml_, 0.8 ml_ to 1 ml_, 0.9 ml_ to 1 ml_, 0.05 ml_ to 0.9 ml_, 0.1 ml_ to 0.9 ml_, 0.2 ml_ to 0.9 ml_, 0.3 ml_ to 0.9 ml_, 0.4 ml_ to 0.9 ml_, 0.5 ml_ to 0.9 ml_, 0.6 ml_ to 0.9 ml_, 0.7 ml_ to 0.9 ml_, 0.8 ml_ to 0.9 ml_, 0.05 ml_ to 0.8 ml_, 0.1 ml_ to 0.8 ml_, 0.2 ml_ to 0.8 ml_, 0.3 ml_ to 0.8 ml_, 0.4 ml_ to 0.8 ml_, 0.5 ml_ to 0.8 ml_, 0.6 ml_ to 0.8 ml_, 0.7 ml_ to 0.8 ml_, 0.05 ml_ to 0.7 ml_, 0.1 ml_ to 0.7 ml_, 0.2 ml_ to 0.7 ml_, 0.3 ml_ to 0.7 ml_, 0.4 ml_ to 0.7 ml_, 0.5 ml_ to 0.7 ml_, 0.6 ml_ to 0.7 ml_, 0.05 ml_ to 0.6 ml_, 0.1 ml_ to 0.6 ml_, 0.2 ml_ to 0.6 ml_, 0.3 ml_ to 0.6 ml_, 0.4 ml_ to 0.6 ml_, 0.5 ml_ to 0.6 ml_, 0.05 ml_ to 0.5 ml_, 0.1 ml_ to 0.5 ml_, 0.2 ml_ to 0.5 ml_,

0.3 ml_ to 0.5 ml_, 0.4 ml_ to 0.5 ml_, 0.05 mL to 0.4 ml_, 0.1 mL to 0.4 ml_, 0.2 mL to 0.4 ml_, 0.3 mL to 0.4 ml_, 0.05 mL to 0.3 mL, 0.1 mL to 0.3 mL, or 0.2 mL to 0.3 mL.

After a period of time, such as from about 1 day to about 6 weeks, or more, the physician may conduct an analysis to determine whether the therapeutic agent is still present in vivo at an effective level. The physician may obtain a sample from the patient, such as a blood sample or perilymph sample, and may determine whether the subject is a candidate for a subsequent administration of the therapeutic agent based, for example, on the concentration of the therapeutic agent remaining in the sample and the time from the initial administration at which the sample was obtained. OTHER EMBODIMENTS

All publications, patents, and patent applications mentioned in this specification are incorporated herein by reference to the same extent as if each independent publication or patent application was specifically and individually indicated to be incorporated by reference. While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the invention that come within known or customary practice within the art to which the invention pertains and may be applied to the essential features hereinbefore set forth, and follows in the scope of the claims.

Other embodiments are in the claims.

Claims

WHAT IS CLAIMED IS:

1 . An auricular dosage form comprising a therapeutic agent, a gelling agent, and a permeation enhancing amount of glycerol.

2. The auricular dosage form of claim 1 , wherein the auricular dosage form is hypertonic.

3. The auricular dosage form of claim 2, wherein the calculated osmolarity of the auricular dosage form is at least 400 mOsm/L.

4. The auricular dosage form of claim 3, wherein the calculated osmolarity of the auricular dosage form is at least 500 mOsm/L.

5. The auricular dosage form of claim 1 , wherein the calculated osmolarity of the auricular dosage form is at least 1 ,000 mOsm/L.

6. The auricular dosage form of any one of claims 2 to 4, wherein the calculated osmolarity of the auricular dosage form is 7,000 mOsm/L or less.

7. The auricular dosage form of claim 5, wherein the calculated osmolarity of the auricular dosage form is 6,000 mOsm/L or less.

8. The auricular dosage form of claim 6, wherein the calculated osmolarity of the auricular dosage form is 5,000 mOsm/L or less.

9. The auricular dosage form of claim 7, wherein the calculated osmolarity of the auricular dosage form is 4,000 mOsm/L or less.

10. The auricular dosage form of any one of claims 1 to 9, wherein the auricular dosage form comprises at least 1% (w/v).

11 . The auricular dosage form of claim 10, wherein the auricular dosage form comprises at least 5% (w/v) of glycerol.

12. The auricular dosage form of claim 10, wherein the auricular dosage form comprises at least 10% (w/v) of glycerol.

13. The auricular dosage form of claim 10, wherein the auricular dosage form comprises at least 15% (w/v) of glycerol.

14. The auricular dosage form of claim 10, wherein the auricular dosage form comprises at least 20% (w/v) of glycerol.

15. The auricular dosage form of claim 10, wherein the auricular dosage form comprises at least 25% (w/v) of glycerol.

16. The auricular dosage form of claim 10, wherein the auricular dosage form comprises at least 30% (w/v) of glycerol.

17. The auricular dosage form of claim 10, wherein the auricular dosage form comprises at least 35% (w/v) of glycerol.

18. The auricular dosage form of claim 10, wherein the auricular dosage form comprises at least 40% (w/v) of glycerol.

19. The auricular dosage form of any one of claims 1 to 18, wherein the auricular dosage form comprises 80% (w/v) of glycerol or less.

20. The auricular dosage form of any one of claims 1 to 18, wherein the auricular dosage form comprises 70% (w/v) of glycerol or less.

21 . The auricular dosage form of any one of claims 1 to 18, wherein the auricular dosage form comprises 65% (w/v) of glycerol or less.

22. The auricular dosage form of any one of claims 1 to 18, wherein the auricular dosage form comprises 60% (w/v) of glycerol or less.

23. The auricular dosage form of any one of claims 1 to 18, wherein the auricular dosage form comprises 55% (w/v) of glycerol or less.

24. The auricular dosage form of any one of claims 1 to 18, wherein the auricular dosage form comprises 50% (w/v) of glycerol or less.

25. The auricular dosage form of any one of claims 1 to 18, wherein the auricular dosage form comprises 45% (w/v) of glycerol or less.

26. The auricular dosage form of any one of claims 1 to 18, wherein the auricular dosage form comprises 40% (w/v) of glycerol or less.

27. The auricular dosage form of any one of claims 1 to 16, wherein the auricular dosage form comprises 30% (w/v) of glycerol or less.

28. The auricular dosage form of any one of claims 1 to 27, wherein the gelling agent is hyaluronan, a polyoxyethylene-polyoxypropylene block copolymer, poly(lactic-co-glycolic) acid, polylactic acid, polycaprolactone, alginic acid or a salt thereof, polyethylene glycol, a cellulose, a cellulose ether, a carbomer, agar-agar, gelatin, glucomannan, galactomannan, xanthan gum, chitosan, pectin, starch, tragacanth, carrageenan, polyvinylpyrrolidone, polyvinyl alcohol, paraffin, petrolatum, silicates, fibroin, or a combination thereof.

29. The auricular dosage form of claim 28, wherein the gelling agent is hyaluronan.

30. The auricular dosage form of claim 28, wherein the gelling agent is a polyoxyethylene- polyoxypropylene block copolymer.

31 . The auricular dosage form of claim 30, wherein the polyoxyethylene-polyoxypropylene block copolymer is poloxamer 407, poloxamer 188, or a combination thereof.

32. The auricular dosage form of claim 28, wherein the gelling agent is a cellulose ether.

33. The auricular dosage form of claim 32, wherein the cellulose ether is methylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, methyl hydroxyethylcellulose, hydroxypropyl methylcellulose, hydroxypropylcellulose, or a combination thereof.

34. The auricular dosage form of claim 28, wherein the gelling agent is fibroin.

35. The auricular dosage form of claim 28, wherein the gelling agent is alginic acid or a salt thereof.

36. The auricular dosage form of any one of claims 28 to 35, wherein the gelling agent is cross- linked.

37. The auricular dosage form of claim 36, wherein the gelling agent is ionically cross-linked.

38. The auricular dosage form of claim 36, wherein the gelling agent is covalently cross-linked.

39. The auricular dosage form of any one of claims 1 to 38, wherein the concentration of the therapeutic agent is at least 0.05M.

40. The auricular dosage form of claim 39, wherein the concentration of the therapeutic agent is at least 0.1 M.

41 . The auricular dosage form of claim 39, wherein the concentration of the therapeutic agent is at least 0.2M.

42. The auricular dosage form of claim 39, wherein the concentration of the therapeutic agent is at least 0.3M.

43. The auricular dosage form of claim 39, wherein the concentration of the therapeutic agent is at least 0.4M.

44. The auricular dosage form of claim 39, wherein the concentration of the therapeutic agent is at least 0.5M.

45. The auricular dosage form of claim 39, wherein the concentration of the therapeutic agent is at least 1 .0M.

46. The auricular dosage form of any one of claims 1 to 45, wherein the concentration of the therapeutic agent is 2.5M or less.

47. The auricular dosage form of claim 46, wherein the concentration of the therapeutic agent is 2.0M or less.

48. The auricular dosage form of claim 46, wherein the concentration of the therapeutic agent is 1 .5M or less.

49. The auricular dosage form of any one of claims 1 to 45, wherein the concentration of the therapeutic agent is 1 .0M or less.

50. The auricular dosage form of any one of claims 1 to 44, wherein the concentration of the therapeutic agent is 0.5M or less.

51 . The auricular dosage form of any one of claims 1 to 43, wherein the concentration of the therapeutic agent is 0.4M or less.

52. The auricular dosage form of any one of claims 1 to 42, wherein the concentration of the therapeutic agent is 0.3M or less.

53. The auricular dosage form of any one of claims 1 to 41 , wherein the concentration of the therapeutic agent is 0.2M or less.

54. The auricular dosage form of any one of claims 1 to 53, further comprising a pharmaceutically acceptable liquid solvent.

55. The auricular dosage form of claim 54, wherein pharmaceutically acceptable liquid solvent is water.

56. The auricular dosage form of any one of claims 1 to 55, wherein the pH of the dosage form is 6.5 to 8.5.

57. The auricular dosage form of any one of claims 1 to 56, wherein the auricular dosage form is an auricular unit dosage form.

58. The auricular dosage form of claim 57, wherein the auricular unit dosage form has a volume of at least 0.05 ml_.

59. The auricular dosage form of claim 57, wherein the auricular unit dosage form has a volume of at least 0.1 ml_.

60. The auricular dosage form of claim 57, wherein the auricular unit dosage form has a volume of at least 0.3 ml_.

61 . The auricular dosage form of claim 57, wherein the auricular unit dosage form has a volume of at least 0.5 ml_.

62. The auricular dosage form of claim 57, wherein the auricular unit dosage form has a volume of at least 0.8 ml_.

63. The auricular dosage form of any one of claims 57 to 62, wherein the auricular unit dosage form has a volume of 1 ml_ or less.

64. The auricular dosage form of any one of claims 57 to 62, wherein the auricular unit dosage form has a volume of 0.8 ml_ or less.

65. The auricular dosage form of any one of claims 57 to 61 , wherein the auricular unit dosage form has a volume of 0.5 ml_ or less.

66. The auricular dosage form of any one of claims 57 to 60, wherein the auricular unit dosage form has a volume of 0.3 ml_ or less.

67. The auricular dosage form of any one of claims 1 to 66, wherein the therapeutic agent is an anti platinum chemoprotectant agent.

68. The auricular dosage form of claim 67, wherein the anti-platinum chemoprotectant agent is an alkaline or ammonium thiosulfate salt or a solvate thereof, an alkaline diethyldithiocarbamate salt, amifostine, methionine, N-acetylcysteine, cysteine, 2-aminoethanethiol, glutathione (GSH) or a C1-C6 alkyl ester thereof, lysine, histidine, arginine, ethylene diamine tetraacetic acid, dimercaprol, dimercaptosuccinic acid, dimercapto-propane sulfonate salt, penicillamine, a-lipoic acid, or fursultiamine, or a salt thereof.

69. The auricular dosage form of claim 68, wherein the anti-platinum chemoprotectant agent is an alkaline thiosulfate salt, ammonium thiosulfate salt, or a solvate thereof.

70. The auricular dosage form of claim 69, wherein the alkaline thiosulfate salt is sodium thiosulfate or a solvate thereof.

71 . The auricular dosage form of claim 68, wherein the anti-platinum chemoprotectant agent is N- acetylcysteine or a salt thereof.

72. The auricular dosage form of any one of claims 1 to 66, wherein the therapeutic agent is a TrkB receptor agonist antibody.

73. The auricular dosage form of any one of claims 1 to 66, wherein the therapeutic agent is a TrkC receptor agonist antibody.

74. The auricular dosage form of any one of claims 1 to 66, wherein the therapeutic agent is an Atohl modulator.

75. The auricular dosage form of any one of claims 1 to 66, wherein the therapeutic agent is a WNT modulator.

76. The auricular dosage form of any one of claims 1 to 66, wherein the therapeutic agent is a neurotrophin selected from neurotrophin-3 (NT-3), nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), ciliary neurotrophic factor (CNTF), glial cell-line derived neurotrophic factor (GDNF), neurotrophin-4 (NT-4), fibroblast growth factor (FGF), insulin-like growth factor (IGF), epidermal growth factor (EGF), platelet-derived growth factor (PGF), mesencephalic astrocyte-derived neurotrophic factor (MANF), cerebral dopamine neurotrophic factor (CDNF), a pan-neurotrophic factor, a chimeric neurotrophic factor, and combinations thereof.

77. The auricular dosage form of claim 76, wherein the neurotrophic factor is NT-3.

78. The auricular dosage form of claim 77, wherein the NT-3 has an amino acid sequence having at least 85% sequence identity to the amino acid sequence of SEQ ID NO: 1 , SEQ ID NO: 7, or SEQ ID NO: 8.

79. The auricular dosage form of claim 78, wherein the NT-3 has an amino acid sequence having at least 90% sequence identity to the amino acid sequence of SEQ ID NO: 1 , SEQ ID NO: 7, or SEQ ID NO: 8.

80. The auricular dosage form of claim 79, wherein the NT-3 has an amino acid sequence having at least 95% sequence identity to the amino acid sequence of SEQ ID NO: 1 , SEQ ID NO: 7, or SEQ ID NO: 8.

81 . The auricular dosage form of claim 80, wherein the NT-3 has the amino acid sequence of SEQ ID NO: 1.

82. The auricular dosage form of claim 80, wherein the NT-3 has the amino acid sequence of SEQ ID NO: 7.

83. The auricular dosage form of claim 80, wherein the NT-3 has the amino acid sequence of SEQ ID NO: 8.

84. The auricular dosage form of claim 77, wherein the NT-3 is an NT-3 variant having one or more amino acid substitutions relative to amino acid sequence of SEQ ID NO: 8.

85. The auricular dosage form of claim 84, wherein the NT-3 variant has the amino acid sequence of any one of SEQ ID NOs: 34-46.

86. The auricular dosage form of any one of claims 1 to 85, wherein the therapeutic agent is a glial cell line-derived neurotrophic factor family ligand, a neuropoietic cytokine, an anti-inflammatory cytokine, a neuroprotection agent, growth differentiation factor 11 , erythropoietin (EPO), granulocyte-colony stimulating factor, granulocyte-macrophage colony stimulating factor, growth differentiation factor-9, thrombopoietin, transforming growth factor alpha (TGF-a), stromal cell-derived factor 1 , myostatin, parathyroid hormone, parathyroid hormone related peptide, interleukin 1 receptor antagonist, fibroblast growth factor 18, high-mobility group protein 2, glucocorticoid receptor, fibroblast growth factor 9, hepatocyte growth factor, or a TGFp-superfamily protein.

87. The auricular dosage form of claim 86, wherein the therapeutic agent is a glial cell line-derived neurotrophic factor family ligand selected from glial cell line-derived neurotrophic factor (GDNF), neurturin, artemin, and persephin.

88. The auricular dosage form of claim 86, wherein the therapeutic agent is a neuropoietic cytokine selected from interleukin-6, interleukin-11 , inteleukin-27, leukemia inhibitory factor, cardiotrophin 1 , neuropoietin, cardiotrophin-like cytokine, and fibroblast growth factor 2.

89. The auricular dosage form of claim 86, wherein the therapeutic agent is an anti-inflammatory cytokine selected from interleukin-4 and interleukin-10.

90. The auricular dosage form of claim 86, wherein the therapeutic agent is a neuroprotection agent selected from neuregulin-1 and vascular endothelial growth factor (VEGF).

91 . The auricular dosage form of claim 86, wherein the therapeutic agent is a TGFp-superfamily protein selected from TGFp, TGFp3, BMP2, and BMP7.

92. The auricular dosage form of any one of claims 1 to 66, wherein the therapeutic agent is a nucleic acid vector.

93. The auricular dosage form of claim 92, wherein the nucleic acid vector is a plasmid, cosmid, artificial chromosome, or viral vector.

94. The auricular dosage form of claim 93, wherein the viral vector is an adeno-associated virus (AAV), adenovirus, lentivirus, retrovirus, poxvirus, baculovirus, herpes simplex virus, or a vaccinia virus.

95. The auricular dosage form of claim 94, wherein the viral vector is an AAV vector.

96. The auricular dosage form of claim 95, wherein the serotype of the AAV vector is selected from the group consisting of AAV1 , AAV2, AAV3, AAV4, AAV5, AAV6, AAV7, AAV8, AAV9, AAV10, rh10, rh39, rh43, rh74, Anc80, Anc80L65, DJ/8, DJ/9, 7m8, PHP.B, PHP.eb, and PHP.S, preferably AAV1 .

97. The auricular dosage form of any one of claims 1 to 66, wherein the therapeutic agent is an antibody or antigen-binding fragment thereof.

98. The auricular dosage form of claim 97, wherein the antibody or antigen-binding fragment thereof is a monoclonal antibody or antigen-binding fragment thereof, a polyclonal antibody or antigen-binding fragment thereof, a humanized antibody or antigen-binding fragment thereof, a bispecific antibody or antigen-binding fragment thereof, a dual-variable immunoglobulin domain, a single-chain Fv molecule (scFv), a diabody, a triabody, a nanobody, an antibody-like protein scaffold, a Fv fragment, a Fab fragment, a F(ab’)2 molecule, or a tandem di-scFv.

99. The auricular dosage form of any one of claims 1 to 66, wherein the therapeutic agent is a small molecule.

100. The auricular dosage form of claim 99, wherein the small molecule is not naturally round window membrane-penetrant.

101 . The auricular dosage form of any one of claims 1 to 66, wherein the therapeutic agent is an interfering RNA.

102. The auricular dosage form of claim 101 , wherein the interfering RNA is a short interfering RNA (siRNA), a short hairpin RNA (shRNA), or a micro RNA (miRNA).

103. The auricular dosage form of any one of claims 1 to 102, wherein the dosage form is a gel at normal human body temperature.

104. The auricular dosage form of claim 103, wherein the gel has a dynamic viscosity of at about 100 cP to about 1 ,000,000 cP.

105. The auricular dosage form of any one of claims 1 to 104, wherein the auricular dosage form further comprises one or more agents selected from the group consisting of an antimicrobial agent, an arylcycloalkylamine, an elipticine derivative, an anti-apoptotic agent, a c-JNK inhibitor, an antioxidant, an NSAID, an analgesic, a neuroprotection agent, a glutamate modulator, an interleukin 1 modulator, an interleukin-1 antagonist, a corticosteroid, an anti-TNF agent, a calcineurin inhibitor, an IKK inhibitor, an interleukin inhibitor, a platelet activating factor antagonist, a TNF-a converting enzyme (TACE) inhibitor, a Toll-like receptor inhibitor, an autoimmune agent, an IL-1 modulator, an RNA interference agent, an aquaporin modulator, an estrogen-related receptor beta modulator, a GAP junction protein, a vasopressin receptor modulator, an NMDA receptor modulator, an ENaC receptor modulator, an osmotic diuretic, a progesterone receptor, a prostaglandin, a cytotoxic agent, a cytoprotective agent, an anti-intercellular adhesion molecule-1 antibody, an Atohl modulator, a Mathl modulator, a BFtN-3 modulator, a carbamate, an estrogen receptor, a fatty acid, a gamma-secretase inhibitor, a glutamate-receptor modulator, a neurotrophic agent, salicylic acid, nicotine, a retinoblastoma protein modulator, an ion channel blocker, a thyroid hormone receptor modulator, a TRPV modulator, an adenosine modulator, a KCNQ modulator, a P2X modulator, a CNS modulating agent, an anticholinergic, an antihistamine, a GABA receptor modulator, a neurotransmitter reuptake inhibitor, a thyrotropin-releasing hormone, a free radical modulator, a metal atom chelator, a mitochondrial modulator, a nitric oxide synthase modulator, a sirtuin modulator, a purinergic receptor modulator, a truncated TrkC or TrkB antagonist, a truncated TrkC or TrkB isoform, a nucleic acid polymer antagonist, a small molecule antagonist, a polypeptide antagonist, a non-natural TrkC or TrkB agonist, a neurotrophin variant, a WNT modulator, anti-platinum chemoprotectant agent, a glycogen synthase kinase inhibitor, a protein kinase C beta modulator, a repulsive guidance molecule a (RGMa) inhibitor, a neogenin inhibitor, a SK2 channel activator, a BK channel activator, a sphingosine-1 -phosphate receptor modulator, a sternness driver, a differentiation inhibitor, an N-Methyl-D-Aspartate (NMDA) receptor antagonist, a histone deacetylase (FIDAC) inhibitor, a proteasome inhibitor, an EZFI2/FIMT inhibitor, a notch inhibitor, ebselen, ancrod, an a-amino-3-hydroxy-5- methyl-4-isoxazolepropionic acid (AMPA) glutamate-positive allosteric modulator, D-methionine, an antagonist of histamine type 4 receptors, a chemotherapeutic accumulation reducer, choline ester, plant alkaloid, reversible cholinesterase inhibitor, acetylcholine release promoter, anti-adrenergic agent, a sympathomimetic agent, an antineoplastic agent, R(+)-N-propargyl-1-aminoindan, and R-azasetron besylate.

106. The auricular dosage form of any one of claims 1 to 104, wherein the auricular dosage form further comprises one or more agents selected from the group consisting of an antimicrobial agent, an anti-apoptotic agent, a c-JNK inhibitor, an antioxidant, an NSAID, an analgesic, a neuroprotection agent, a glutamate modulator, an interleukin 1 modulator, an interleukin-1 antagonist, a corticosteroid, an anti- TNF agent, a calcineurin inhibitor, an IKK inhibitor, an interleukin inhibitor, a platelet activating factor antagonist, a TNF-a converting enzyme (TACE) inhibitor, a Toll-like receptor inhibitor, an IL-1 modulator, an RNA interference agent, an aquaporin modulator, an estrogen-related receptor beta modulator, a GAP junction protein, a vasopressin receptor modulator, an NMDA receptor modulator, an ENaC receptor modulator, an osmotic diuretic, a progesterone receptor, a prostaglandin, a cytotoxic agent, a cytoprotective agent, an anti-intercellular adhesion molecule-1 antibody, an Atohl modulator, a Mathl modulator, a BRN-3 modulator, a carbamate, an estrogen receptor, a fatty acid, a gamma-secretase inhibitor, a glutamate-receptor modulator, a neurotrophic agent, salicylic acid, nicotine, a retinoblastoma protein modulator, an ion channel blocker, a thyroid hormone receptor modulator, a TRPV modulator, an adenosine modulator, a KCNQ modulator, a P2X modulator, a CNS modulating agent, an anticholinergic, an antihistamine, a GABA receptor modulator, a neurotransmitter reuptake inhibitor, a thyrotropin releasing hormone, a free radical modulator, a metal atom chelator, a mitochondrial modulator, a nitric oxide synthase modulator, a sirtuin modulator, a purinergic receptor modulator, a truncated TrkC or TrkB antagonist, a truncated TrkC or TrkB isoform, a non-natural TrkC or TrkB agonist, a neurotrophin variant, a WNT modulator, anti-platinum chemoprotectant agent, a glycogen synthase kinase inhibitor, a protein kinase C beta modulator, a repulsive guidance molecule a (RGMa) inhibitor, a neogenin inhibitor, a SK2 channel activator, a BK channel activator, a sphingosine-1 -phosphate receptor modulator, an N-Methyl-D- Aspartate (NMDA) receptor antagonist, a histone deacetylase (HDAC) inhibitor, a proteasome inhibitor, an EZH2/HMT inhibitor, a notch inhibitor, ebselen, ancrod, an a-amino-3-hydroxy-5-methyl-4- isoxazolepropionic acid (AMPA) glutamate-positive allosteric modulator, D-methionine, an antagonist of histamine type 4 receptors, reversible cholinesterase inhibitor, acetylcholine release promoter, anti- adrenergic agent, a sympathomimetic agent, an antineoplastic agent, R(+)-N-propargyl-1-aminoindan, and R-azasetron besylate.

107. A method of delivering a therapeutic agent across the round window membrane of a subject, the method comprising administering to the subject a therapeutically effective amount of the auricular dosage form of any one of claims 1 to 106.

108. The method of claim 107, wherein the auricular dosage form is administered to or near the round window membrane.

109. The method of claim 107 or 108, wherein the auricular dosage form is administered intratympanically or transtympanically.

110. The method of any one of claims 106 to 109, wherein the method is used to treat an otic disease.

111. The method of claim 110, wherein the otic disease is ceruminosis or ceruminosis associated with an otic disease or condition, ear pruritus, otitis externa, otalgia, tinnitus, vestibular dysfunction, vertigo, dizziness, loss of balance, ear fullness, hearing loss, Meniere's disease, sensorineural hearing loss, noise-induced hearing loss, age-related hearing loss (presbycusis), ototoxic drug-induced hearing loss, hearing loss related to head trauma, hearing loss related to infection, autoimmune ear disease, ototoxicity, excitotoxicity, hidden hearing loss, cochlear synaptopathy, endolymphatic hydrops, labyrinthitis, Ramsay Hunt's Syndrome, vestibular neuronitis, or microvascular compression syndrome, hyperacusis, presbystasis, central auditory processing disorder, auditory neuropathy, improvement of cochlea implant performance, or a combination thereof.

112. A method of treating a subject having or at risk of developing hearing loss, comprising administering to the subject a therapeutically effective amount of the auricular dosage form of any one of claims 1 to 106.

113. The method of claim 112, wherein the hearing loss is genetic hearing loss.

114. The method of claim 113, wherein the genetic hearing loss is autosomal dominant hearing loss, autosomal recessive hearing loss, or X-linked hearing loss.

115. The method of claim 114, wherein the hearing loss is acquired hearing loss.

116. The method of claim 115, wherein the acquired hearing loss is noise-induced hearing loss, age- related hearing loss, disease or infection-related hearing loss, head trauma-related hearing loss, or ototoxic drug-induced hearing loss.

117. A method of treating a subject having or at risk of developing vestibular dysfunction, comprising administering to the subject a therapeutically effective amount of the auricular dosage form of any one of claims 1 to 106.

118. The method of claim 117, wherein the vestibular dysfunction is vertigo, dizziness, or imbalance.

119. A method of promoting hair cell regeneration in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of the auricular dosage form of any one of claims 1 to 106.

120. A method of promoting spiral ganglion neuron (SGN) regeneration in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of the auricular dosage form of any one of claims 1 to 106.

121 . A method of preventing or reducing ototoxic drug-induced hair cell damage or death in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of the auricular dosage form of any one of claims 1 to 106.

122. A method of preventing or reducing ototoxic drug-induced SGN damage or death, comprising administering to the subject a therapeutically effective amount of the auricular dosage form of any one of claims 1 to 106.

123. The method of claim 116, 121 , or 122, wherein the ototoxic drug is selected from the group consisting of aminoglycosides, antineoplastic drugs, ethacrynic acid, furosemide, salicylates, and quinine.

124. A method of preventing or mitigating platinum-induced ototoxicity in a subject in need thereof, the method comprising administering to the subject a therapeutically effective amount of the auricular dosage form of any one of claims 1 to 106.

125. A method of treating a subject having or at risk of developing tinnitus, comprising administering to the subject a therapeutically effective amount of the auricular dosage form of any one of claims 1 to 106.

126. A method of preventing or reducing hair cell damage or death in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of the auricular dosage form of any one of claims 1 to 106.

127. A method of preventing or reducing SGN damage or death in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of the auricular dosage form of any one of claims 1 to 106.

128. The method of any one of claims 110 to 127, wherein the method further comprises evaluating the hearing of the subject prior to administering the auricular dosage form.

129. The method of any one of claims 110 to 128, wherein the method further comprises evaluating the hearing of the subject after administering the auricular dosage form.

130. The method of any one of claims 110 to 129, wherein the method further comprises evaluating the vestibular function of the subject prior to administering the auricular dosage form.

131 . The method of any one of claims 110 to 130, wherein the method further comprises evaluating the vestibular function of the subject after administering the auricular dosage form.

132. The method of any one of claims 110 to 128, wherein the auricular dosage form is locally administered.

133. The method of claim 132, wherein the auricular dosage form is administered intratympanically or transtympanically.

134. The method of any one of claims 110 to 133, wherein the auricular dosage form is administered in an amount sufficient to prevent or reduce hearing loss, prevent or reduce vestibular dysfunction, prevent or reduce tinnitus, delay the development of hearing loss, delay the development of vestibular dysfunction, slow the progression of hearing loss, slow the progression of vestibular dysfunction, improve hearing, improve vestibular function, improve hair cell function, prevent or reduce hair cell damage, prevent, slow, or reduce hair cell death, promote or increase hair cell survival, increase hair cell numbers, promote or induce hair cell regeneration, improve SGN function, prevent or reduce SGN damage, prevent, slow, or reduce SGN death, promote or increase SGN survival, increase SGN numbers, promote or induce SGN regeneration, preserve ribbon synapses, promote or increase ribbon synapse formation, maintain the connections between hair cells and SGNs, or increase or restore the connections between hair cells and SGNs.

135. The method of any one of claims 107 to 134, wherein the subject is a mammalian subject.

136. The method of claim 135, wherein the mammalian subject is a human subject.