WO2019002869A1

WO2019002869A1 - Chemotherapy

Info

Publication number: WO2019002869A1
Application number: PCT/GB2018/051811
Authority: WO
Inventors: Ruman RAHMAN; Richard Grundy; Toby Gould; Stuart Smith; Cheryl Rahman; Kevin Shakesheff
Original assignee: The University Of Nottingham
Priority date: 2017-06-29
Filing date: 2018-06-28
Publication date: 2019-01-03
Also published as: GB201710414D0

Abstract

The invention relates to a polymer paste for local chemotherapeutic drug delivery to a tissue site, the polymer paste comprising: a polymer and a carrier; and a pH sensitive chemotherapeutic alkylating agent, wherein the polymer paste is capable of solidifying into a matrix in situ at the tissue site, and wherein the polymer paste has an acidic pH of 6 or less, or an alkali pH of 8 or more. The invention further relates to use of the polymer paste and a kit to provide the polymer paste.

Description

CHEMOTHERAPY

The present invention relates to a polymer paste for local chemotherapeutic drug delivery to a tissue site and the use of such a polymer paste in treatments of cancer.

Glioblastoma (GBM) is the most common high-grade primary brain tumour in adults. It belongs to a group of brain tumours known as gliomas which grows from a brain cell called a glial cell. The median survival for adult GBM patients is around 14 months despite, surgery, chemotherapy and radiotherapy. Paediatric glioblastoma (pGBM) is one of the leading causes of childhood death due to cancer worldwide . The disease is currently incurable with a poor prognosis; only 19% of patients survive for 5 years or more after being diagnosed with pGBM. Chemotherapy has shown little effectiveness for adult or pGBM using current therapy methods. One difficulty when considering chemotherapy for brain cancers is that the brain' s structure, specifically the blood-brain barrier prevents drugs from reaching the tumour in effective doses. This hampers the delivery of drugs through the bloodstream or when given as an oral dose . This makes it particularly attractive to deliver drugs directly to brain tumours (local delivery) following surgery. Delivering drugs in this way potentially ensures that therapeutic doses of anti-cancer agents are delivered close to the residual brain cancer cells left behind after surgery, but also avoids the damage caused to healthy parts of the body when drugs are given systemically through the bloodstream. Wafer implants are a way of giving chemotherapy for brain tumours into the area of the tumour. The wafer is made of polymer that contains a chemotherapy drug. One example is the Gliadel™ Wafer (carmustine implant), which is indicated in patients with newly diagnosed high-grade malignant glioma as an adjunct to surgery and radiation, and also indicated in patients with recurrent glioblastoma multiforme as an adjunct to surgery. The Gliadel™ Wafer is implanted in the brain along the walls and floor of the cavity created after a malignant glioma has been surgically removed. Up to 8 wafers may be placed in the area where the tumour was located, and they dissolve in 2-3 weeks. The number of wafers implanted depends on the size of the space left after the removal of the tumour. As they degrade, the wafers release carmustine into the surrounding cells. This type of drug delivery has previously been shown to be successful in increasing survival (2 month survival benefit) in adult GBM patients. However, an issue with the chemotherapy wafer technology currently in use is that the disks are solid and have a tendency to slip/move position, and only release one drug, namely carmustine, as the polymer was tailored specifically for this drug. There is a clinical need to further develop local chemotherapy regimes that can eradicate residual tumour cells following surgical resection, thereby reducing the risk of tumour recurrence.

An alternative delivery system to wafer implants is the use of a biodegradable polymer paste. This formulation is in early pre-clinical development stages and consists of temperature-sensitive poly(lactic-co-glycolic acid) (PLGA)/poly(ethylene glycol) (PEG) microparticles. When the micro particles are mixed with a carrier solution they form a paste that can be moulded around the tumour resection cavity. The microparticles then fuse together at body temperature, which causes the paste to solidify into a matrix that retains its shape within the cavity. Chemotherapeutic drugs loaded into the carrier solution are released over time from the polymer matrix. Trichostatin A, etoposide and methotrexate have been released from the matrices over a 3-4 week period in vitro and etoposide has been released over 3 days in vivo, with released agents retaining cytotoxic capabilities. PLGA/PEG microparticle-based matrices moulded around a resection cavity wall are distinguishable in clinical scanning modalities. Matrices are non-toxic in vitro suggesting good biocompatibility in vivo. The polymer withstands fractionated radiotherapy, with no disruption of microparticle structure. This PLGA/PEG delivery system offers an innovative intra-cavity approach to administer chemotherapeutics for improved local control of malignant brain tumours. (Rahman et al 2013. PLOS one. Volume 8. Issue 10. pp. 1 - 10. e77435, which is incorporated herein by reference).

Temozolomide (TMZ) is a prodrug and an imidazotetrazine derivative of the alkylating agent dacarbazine. It is an oral chemotherapy drug typically used as a treatment of some brain cancers; as a second-line treatment for astrocytoma and a first-line treatment for GBM. Local delivery of TMZ is extremely difficult due to its stability. At neutral/physiological pH (pH 7) TMZ spontaneously converts by hydrolysis from TMZ (the pro-drug) to MTIC (5-(3-methyltriazen- l -yl)imidazole-4- carboxamide) (an intermediate), with a half-life for this conversion of 1.8 hours. The intermediate MTIC is itself also highly unstable at neutral/physiological pH with a half-life only slightly longer ( 1.9 hours) to convert to the active species, which is the methyldiazonium ion (a proximate reactive DNA methylating species), and a non- active AIC molecule (See Biochemistry. 1994 Aug 9;33(3 1): 9045 -5 1). Therefore, localised TMZ or MTIC delivery is severely hampered by the instability of each compound at neutral/physiological pH. Although a number of studies purport to observe TMZ release over a period of 2-7 days, they do not directly address this issue of instability and typically only indirectly measure TMZ release by proxy of how much TMZ remains in the biomaterial acting as the drug delivery system or do not mention how TMZ instability is overcome. These studies therefore do not take measures to overcome the short half-life of TMZ within a saline environment (Ling Y et al 2012. Int. Journal of Pharmaceutics 430: 266-275); Xu Y et al 2016. Oncotarget 7( 15):20890-20901).

A series of imidazotetrazine analogues of TMZ have been synthesised which are potentially more potent clinically, but which are also highly unstable in neutral pH, hampering their use in localised brain drug delivery systems (Zhang et al. Oncology 201 1 ;80: 195-207 DOI: 10.1 159/000327837).

Therefore, an aim of the present invention is to provide a local delivery platform with a tuneable pH environment specifically for the delivery of pH sensitive imidazotetrazines, thereby potentially improving chemotherapeutic approaches to treat tumours.

According to a first aspect of the present invention, there is provided a polymer paste for local chemotherapeutic drug delivery to a tissue site, the polymer paste comprising:

a polymer and a carrier; and

a pH sensitive chemotherapeutic alkylating agent,

wherein the polymer paste is capable of solidifying into a matrix in situ at the tissue site, and

wherein the polymer paste has an acidic pH of 6 or less, or an alkali pH of 8 or more.

In one embodiment, the polymer paste has an acidic pH of 6 or less when the chemotherapeutic alkylating agent is less stable at an alkali or neutral pH. In another embodiment, the polymer paste has an alkali pH of 8 or more when the chemotherapeutic alkylating agent is less stable at an acidic or neutral pH.

The invention offers an innovative approach to administer chemotherapeutics for improved local and potentially micrometastatic control of malignant brain tumours. Other tumour types requiring surgical excision, and leaving a cavity, would also potentially benefit from the polymer paste of the invention which can control local delivery of a chemotherapeutic alkylating agent to the remaining tissue and where the polymer paste will remain in situ. In particular, the polymer paste can be delivered intra-cavity and the polymer paste can be applied around the lining (wall) of the surgical cavity and will take the form of that cavity and remain in place for a sufficient period of time without slipping or dispersing. This advantageously overcomes the slippage issues of solid Gliadel™ Wafers which are pre-set/pre- solidified into a disk shape and cannot conform to the contours of the cavity. With the polymer paste around the walls of the surgical cavity the chemotherapeutic alkylating agent is closer to the residual cancer cells left behind. This delivery mode is an enhancement over pre-formed solid polymers such as the Gliadel Wafer.

Furthermore, the pH of the polymer paste can be altered to increase the stability of pH sensitive alkylating agents, such as TMZ, for longer-term controlled drug release . For example, in the case of TMZ, which is a pro-drug, the TMZ can be held in the matrix where it is protected from rapid conversion to the intermediate and active form by the acidic environment provided in the matrix. Upon controlled release from the matrix, TMZ and MTIC are exposed to a higher more neutral pH environment in the tissue. The invention specifically permits the delivery of pH-sensitive imidazotetrazines and other anti-cancer agents locally via the tuneable pH environment of the local delivery system.

By using a polymer paste which solidifies/sets to form a matrix after administration, a matrix can be formed which conforms to the shape of where it is placed, for example, the shape of a tissue cavity into which it is placed. This overcomes a problem with matrices or scaffolds fabricated prior to administration which must be fabricated to a specific shape ahead of administration, and cannot be inserted through a bottle-neck in a cavity. In one embodiment, the polymer paste is capable of solidifying into a matrix in situ at the tissue site.

The polymer paste may have a paste consistency. The polymer paste may be malleable . For example the polymer paste may be spreadable with a tool such as a spatula. The polymer paste may have a paste consistency prior to solidification into a matrix in situ at the tissue site. In one embodiment, the polymer paste may comprise temperature-sensitive polymer particles that solidify into a matrix in situ at the tissue site of delivery.

The polymer paste may (or may be arranged to) not dissipate when administered in situ, as water would, but instead takes the form of the site where it is administered. In one embodiment, the polymer paste remains substantially where it is applied, and does not dissipate. For example, more than about 90%, 95%, 98%, 99%, or 99.5% by weight of the polymer paste provided into a particular tissue site may remain at the site (prior to any degradation) .

Solidification of the matrix from the polymer paste, once administered to a human or non-human animal, may take from about 20 seconds to about 24 hours, alternatively between about 1 minute and about 5 hours, alternatively between about 1 minute and about 1 hour, alternatively less than about 30 minutes, alternatively less than about 20 minutes. In one embodiment, the solidification occurs in between about 1 minute and about 20 minutes from administration. The skilled person will understand that the pH of the polymer paste may be set at a level that is optimal for the desired stability of the chemotherapeutic alkylating agent, whilst also being biocompatible (e.g. avoiding-damage) with the tissue site . For example, for TMZ the optimal pH for stability is about 3. In one embodiment, the polymer paste has an acidic pH of about 5.5 or less. In another embodiment, the polymer paste has an acidic pH of about 5 or less. In another embodiment, the polymer paste has an acidic pH of about 4.5 or less. In another embodiment, the polymer paste has an acidic pH of about 4 or less. In another embodiment, the polymer paste has an acidic pH of about 3.5 or less. In another embodiment, the polymer paste has an acidic pH of about 3.2 or less. In another polymer paste, the polymer paste has an acidic pH of 3 or less. In another embodiment, the polymer paste has an acidic pH of between about 2 and about 6. In another embodiment, the polymer paste has an acidic pH of between about 2 and about 5. In another embodiment, the polymer paste has an acidic pH of between about 2 and about 4. In another embodiment, the polymer paste has an acidic pH of between about 2 and about 3.5. In another embodiment, the polymer paste has an acidic pH of between about 2.5 and about 4. In another embodiment, the polymer paste has an acidic pH of between about 2.5 and about 3.5. In another embodiment, the polymer paste has an acidic pH of between about 2.5 and about 3.2. In another embodiment, the polymer paste has an acidic pH of between about 2.8 and about 3.2. In another embodiment, the polymer paste has an acidic pH of between about 2.9 and about 3. 1. In another embodiment, the polymer paste has an acidic pH of about 3.

In one embodiment, the polymer paste has an alkali pH of about 8 or more. In another embodiment, the polymer paste has an alkali pH of about 8.5 or more. In another embodiment, the polymer paste has an alkali pH of about 9 or more. In another embodiment, the polymer paste has an alkali pH of about 9.5 or more. In another embodiment, the polymer paste has an alkali pH of about 10 or more. In another embodiment, the polymer paste has an alkali pH of between about 8 and about 10. In another embodiment, the polymer paste has an alkali pH of between about 8.5 and about 10. In another embodiment, the polymer paste has an alkali pH of between about 9 and about 10.

The pH of the overall polymer paste of the invention may be provided by the pH of the carrier solution. In one embodiment, the carrier has an acidic pH of about 5.5 or less. In another embodiment, the carrier has an acidic pH of about 5 or less. In another embodiment, the carrier has an acidic pH of about 4.5 or less. In another embodiment, the carrier has an acidic pH of about 4 or less. In another embodiment, the carrier has an acidic pH of about 3.5 or less. In another embodiment, the carrier has an acidic pH of about 3.2 or less. In another embodiment, the carrier has an acidic pH of 3 or less. In another embodiment, the carrier has an acidic pH of between about 2 and about 6. In another embodiment, the carrier has an acidic pH of between about 2 and about 5. In another embodiment, the carrier has an acidic pH of between about 2 and about 4. In another embodiment, the carrier has an acidic pH of between about 2 and about 3.5. In another embodiment, the carrier has an acidic pH of between about 2.5 and about 4. In another embodiment, the carrier has an acidic pH of between about 2.5 and about 3.5. In another embodiment, the carrier has an acidic pH of between about 2.5 and about 3.2. In another embodiment, the carrier has an acidic pH of between about 2.8 and about 3.2. In another embodiment, the carrier has an acidic pH of between about 2.9 and about 3.1. In another embodiment, the carrier has an acidic pH of about 3.

In one embodiment, the carrier has an alkali pH of about 8 or more. In another embodiment, the carrier has an alkali pH of about 8.5 or more. In another embodiment, the carrier has an alkali pH of about 9 or more. In another embodiment, the carrier has an alkali pH of about 9.5 or more. In another embodiment, the carrier has an alkali pH of about 10 or more. In another embodiment, the carrier has an alkali pH of between about 8 and about 10. In another embodiment, the carrier has an alkali pH of between about 8.5 and about 10. In another embodiment, the carrier has an alkali pH of between about 9 and about 10. In one embodiment, the acidic pH may be provided by an organic acid in the carrier. In one embodiment the organic acid has a pKa of at least 3. In one embodiment the organic acid has a pKa of at least 3.5, 3.7, 4, 4.2 or 4.5. In one embodiment the organic acid has a pKa of between 3 and 8. In another embodiment the organic acid has a pKa of between 3.5 and 6. The organic acid may comprise acetic acid or lactic acid. The pH may be controlled by a buffer in the carrier, such as an organic acid and its salt. For example, acetic acid with conjugate base sodium acetate .

Advantageously, the use of an organic acid in the carrier can avoid toxicity with the tissue/body of the subject. Additionally organic acids can be compatible with the polymer to avoid premature degradation or hindrance of solidification.

The carrier may be an aqueous carrier, in particular water or an aqueous solution or suspension, such as saline, plasma, buffers, such as Hank's Buffered Salt Solution (HBSS), Dulbecco's PBS, normal PBS and simulated body fluids.

In an embodiment wherein the polymer paste is alkaline pH (e.g. pH 8 or more), the alkaline pH may be provided by a weak base or a salt thereof, in the carrier. In one embodiment, the alkaline pH is provided by an ammonium chloride and ammonia in the carrier, preferably in equal quantity. The skilled person will appreciate that any other suitable alkaline buffer systems may be provided in the carrier for providing an alkaline pH. For example, the carrier may comprise a buffer selected from any of AMPSO, CABS, CHES, CAPS, CAPSO, Tris, Glycinamide, HEPBS or TAPS. The alkaline pH may be provided in the carrier by any buffer system with a pKa above 7.5. In one embodiment, the carrier comprises an organic acid. The skilled person will understand that the amount of organic acid in the carrier may be sufficient to provide the required pH of the carrier and/or polymer paste, such as less than pH6 or other pH options of the carrier and/or polymer paste provided according to the invention. The carrier may comprise between 0.05% and 0. 1 % v/v organic acid. For example, the carrier may comprise between 0.01 % and 0. 1 % v/v lactic acid. Alternatively, the carrier may comprise between 0.04% and 0.06% v/v lactic acid. In one embodiment, the carrier may comprise 0.05% v/v lactic acid.

The carrier may comprise between 0.01 % and 0.2% v/v acetic acid. Alternatively, the carrier may comprise between 0.04% and 0.2% v/v acetic acid. Alternatively, the carrier may comprise between 0.05% and 0. 15 % v/v acetic acid. Alternatively, the carrier may comprise between 0.09% and 0. 15 % v/v acetic acid. Alternatively, the carrier may comprise between 0.09% and 0. 1 1 % v/v acetic acid. In one embodiment, the carrier may comprise 0. 1 % v/v acetic acid.

The carrier may also include other known pharmaceutical excipients in order to improve the stability of the agent.

The polymer paste may comprise from about 20% to about 80% polymer and from about 20% to about 80% carrier; from about 30% to about 70% polymer and from about 30% to about 70% carrier; e.g. the polymer paste may comprise from about 40% to about 60% polymer and from about 40% to about 60% carrier; the polymer paste may comprise about 50% polymer and about 50% carrier. The aforementioned percentages all refer to percentage by weight.

The polymer material may comprise polymer particles, which may be microparticles. The polymer may be in the form of microparticles and/or nanoparticles.

The matrix-forming material may be formulated according to WO200809309 or WO2004084968, both of which are incorporated herein by reference. WO2008093094 and WO2004084968 describe compositions and methods for forming tissue scaffolds from polymer particles, such as PLGA and PLGA/PEG polymer blends. Such scaffolds have been developed to be capable of moulding or injection prior to solidifying in situ in a tissue site. The solidifying in situ can be achieved by, for example, exploiting and tuning the glass transition temperature of the polymer particles for interlinking/crosslinking of the polymer particles at body temperature. Interlinking events can also be facilitated by non-temperature related methods, such as by plasticisation by solvents. The matrix may comprise a porous structure, this may be achieved by leaving gaps between the particles and optionally further providing porous polymer particles. The resulting scaffolds maintain porosity that is useful for control of agent delivery. WO2010100506 (the contents of which are incorporated herein by reference) provides a similar injectable agent delivery system comprising a composition comprising: (i) an injectable scaffold material comprising discrete particles; and (ii) a carrier comprising an agent for delivery. The discrete particles are capable of interacting to form a scaffold/matrix.

Therefore, in one embodiment, the matrix-forming material may comprise polymer particles, for example microparticles. The polymer particles may be discrete in the polymer paste (i.e. not interlinked) prior to solidifying into a matrix.

The polymer particles may be capable of interlinking and solidifying into a matrix by sintering. The polymer particles may be capable of spontaneously solidifying when applied into the body tissue due to an increase in temperature post administration (e.g. increase in the temperature from room temperature to body temperature). This increase in temperature may cause the polymer particles to interact to form a matrix. Solidifying of the polymer particles into a matrix may be triggered by any appropriate means, for example, solidifying may be triggered by a change in temperature, a change in pH, a change in mechanical force (compression), or the introduction of an interlinking, cross-linking, setting agent or catalyst. The polymer of the polymer particles may be temperature sensitive .

The polymer particles may be interlinked or crosslinked by a variety of methods including, for example, physical entanglement of polymer chains, UV cross linking of acrylate polymers, Michael addition reaction of thiolate or acrylate polymers, thiolate polymers cross linked via vinyl sulphones, cross linking via succinimates of vinyl sulphones, cross linking via hydrazines, enzymatic crosslinking (for example, the addition of thrombin to fibrinogen), cross linking via the addition of salts or ions (especially Ca2+ ions), cross linking via isocyanates (for example, hexamethylene diisocyanate).

The polymer particles may be provided dry, for example prior to mixing with any carrier. The polymer particles may be in powder form at room temperature and may create a paste when mixed with the carrier. The polymer particles may be at least partially dispersible in the carrier. The polymer particles may not be soluble in the carrier at a temperature of 37°C or less.

The polymer of the matrix-forming material may be natural or synthetic.

The polymer particles may comprise or consist of one or more polymer. The polymer particles may comprise one or more polymer selected from the group comprising poly (a-hydroxyacids) including poly (D,L-lactide-co-glycolide)(PLGA), poly D,L-lactic acid (PDLLA), polyethyleneimine (PEI), polylactic or polyglcolic acids, poly-lactide poly-glycolide copolymers, and poly-lactide poly-glycolide polyethylene glycol copolymers, polyethylene glycol (PEG), polyesters, poly (ε-caprolactone), poly (3- hydroxy-butyrate), poly (s-caproic acid), poly (p-dioxanone), poly (propylene fumarate), poly (ortho esters), polyol/diketene acetals addition polymers, polyanhydrides, poly (sebacic anhydride) (PSA), poly

(carboxybiscarboxyphenoxyphosphazene) (PCPP), poly [bis (p-carboxyphenoxy) methane] (PCPM), copolymers of SA, CPP and CPM (as described in Tamat and Langer in Journal of Biomaterials Science Polymer Edition, 3, 3 15-353. 1992 and by Domb in Chapter 8 of The Handbook of Biodegradable Polymers, Editors Domb A J and Wiseman R M, Harwood Academic Publishers), poly (amino acids), poly (pseudo amino acids), polyphosphazenes, derivatives of poly [(dichloro) phosphazene], poly [(organo) phosphazenes], polyphosphates, polyethylene glycol polypropylene block co-polymers for example that sold under the trade mark Pluronics™, natural or synthetic polymers such as silk, elastin, chitin, chitosan, fibrin, fibrinogen, polysaccharides (including pectins), alginates, collagen, peptides, polypeptides or proteins, copolymers prepared from the monomers of any of these polymers, random blends of these polymers, any suitable polymer and mixtures or combinations thereof. The polymer particles may comprise polymer selected from the group comprising poly(a-hydroxyacids) such as poly lactic acid (PLA), polyglycolic acid (PGA), poly(D,L-lactide-co-glycolide)(PLGA), poly D, L-lactic acid (PDLLA), poly-lactide poly-glycolide copolymers, and combinations thereof. In one embodiment, the polymer particles comprise PLGA. The polymer particles may comprise polymer which is a blend of a poly(a-hydroxyacid) with poly(ethylene glycol) (PEG), such as a blend of a polymer or copolymer based on glycolic acid and/or lactic acid with PEG.

In one embodiment, the polymer particles comprise PLGA 95 : 5. Alternatively, the polymer particles may comprise PLGA 50: 50. Alternatively, the polymer particles may comprise PLGA 85 : 15. Alternatively, the polymer particles may comprise any PLGA between PLGA 85 : 15 and PLGA 95 : 5. Alternatively, the polymer particles may comprise PLGA 65 : 35. Alternatively, the polymer particles may comprise PLGA 72:25. PLGA having monomer ratios between the above PLGA embodiments may also be considered.

In embodiments wherein PEG is provided as a plasticiser in the polymer particle, the PEG may be up to 10% of the polymer particle content. Alternatively, the PEG may be up to 8% of the polymer particle content. Alternatively, the PEG may be up to 6% of the polymer particle content. Alternatively, the PEG may be up to 3% of the polymer particle content. Alternatively, the PEG may be up to 2% of the polymer particle content. Alternatively, the PEG may be up to 1 % of the polymer particle content. Alternatively, the PEG may be between 1 and 10% of the polymer particle content. Alternatively, the PEG may be between 5 and 8% of the polymer particle content. Alternatively, the PEG may be between 6 and 7% of the polymer particle content.

In embodiments wherein PEG is provided as a plasticiser in the polymer particle, the PEG may have a molecular weight of l OOODa or less. Alternatively the PEG is 800Da or less. Alternatively the PEG is 600Da or less. In one embodiment, the PEG is PEG400.

The polymer particles may comprise a plasticiser, which may or may not be PEG. The plasticiser may comprise PLGA, such as low molecular weight PLGA, for example less than l OKDa PLGA. Additionally or alternatively, the plasticiser may comprise the monomers of PLGA (i.e. DL-lactide and/or glycolide). The plasticiser may, for example, comprise polyethylene glycol (PEG), polypropylene glycol, poly (lactic acid) or poly (glycolic acid) or a copolymer thereof, polycaprolactone, and low molecule weight oligomers of these polymers, or conventional plasticisers, such as, adipates, phosphates, phthalates, sabacates, azelates and citrates.

The polymer particles may be biocompatible and/or biodegradable. By controlling the polymers used in the polymer particles the rate of scaffold degradation may be controlled. The scaffold material may comprise one or more types of polymer particles made from one or more type of polymer. Where more than one type of polymer microparticle is used each polymer particle may have a different solidifying property. For example, the polymer particles may be made from similar polymers but may have different melting temperatures or glass transition points.

In one embodiment, in order for the polymer particles to form a scaffold the temperature around the polymer particles, for example in the human or non-human animal where the polymer paste is administered, is approximately equal to, or greater than, the glass transition temperature of the polymer particles. At such temperatures the polymer particles may inter-link to one or more other polymer particles to form a scaffold. By inter-link it is meant that adjacent polymer particles become joined together. For example, the particles may inter-link due to entanglement of the polymer chains at the surface of one polymer particle with polymer chains at the surface of another polymer particle. There may be adhesion, cohesion or fusion between adjacent polymer particles.

A characteristic for the polymer particles, to form a matrix, may be the glass transition temperature (Tg). The matrix-forming material may comprise polymer particles which are formed of a polymer or a polymer blend that has a glass transition temperature (Tg) either close to or just above body temperature (such as from about 30°C to 45°C, e.g. from about 35°C to 40°C, for example from about 37°C to 40°C). Accordingly, at room temperature the polymer particles are below their Tg and behave as discrete polymer particles, but in the body the polymer particles soften and interact/stick to their neighbours. As the skilled person would appreciate, glass transition temperatures can be measured by differential scanning calorimetry (DSC) or rheology testing. In particular, glass transition temperature may be determined with DSC at a scan rate of 10°C/min in the first heating scan, wherein the glass transition is considered the mid-point of the change in enthalpy. A suitable instrument is a Perkin Elmer (Bucks, United Kingdom) DSC-7.

The polymer particles may be formed from a blend of poly(D,L-lactide-co- glycolide)(PLGA) and poly(ethylene glycol) (PEG) which has a Tg at or above body temperature. At body temperature these polymer particles can interact to from a scaffold, and during this process PEG may be lost from the surface of the polymer particles which will have the effect of raising the Tg and hardening the scaffold structure. The scaffold material may comprise only PLGA/PEG particles or other particle types may be included. In another embodiment, the scaffold material may comprise only PLGA particles.

The polymer particles may be solid, that is with a solid outer surface, or they may be porous. The polymer particles may be irregular or substantially spherical in shape . The polymer particles may be microparticles. The microparticles may have a size in their longest dimension of between about 300 and about 500 μιη. In another embodiment, the polymer microparticles may be 100 μιη or less. In another embodiment, the polymer microparticles may be 50 μιη or less. For example, the polymer microparticles may be between about 20 μιη and about 100 μιη, alternatively between about 20 μιη and about 50 μιη, alternatively between about 20 μιη and about 30 μιη. The size of the polymer particles may refer to the average size of a population of polymer microparticles.

The polymer microparticles may have a size in their longest dimension, or their diameter if they are substantially spherical, of less than about 3000μιη and optionally more than about Ι μιη. In one embodiment, the particles have a size in their longest dimension, or their diameter, of less than about Ι ΟΟΟμιη. The polymer microparticles may have a size in their longest dimension, or their diameter, of between about 50μιη and about 500μιη, alternatively between about Ι ΟΟμιη and about 500μιη. Polymer microparticles of the desired size may be unable to pass through a sieve or filter with a pore size of about 50μιη, but will pass through a sieve or filter with a pore size of about 500μηι. Alternatively, polymer microparticles of the desired size may be unable to pass through a sieve or filter with a pore size of about 200μιη, but will pass through a sieve or filter with a pore size of about 500μιη.

In an embodiment, wherein the polymer particles and/or carrier comprise a plasticiser, the solidifying of the matrix may be triggered by plasticiser interaction with the polymer particles, such that they inter-link to form the matrix. In particular, the plasticiser may alter the surface chemistry of the polymer particles such that the surface Tg is decreased, thereby allowing the polymer particles to stick/inter-link together.

The scaffold may form without the generation of heat or loss of an organic solvent. In one embodiment, the pH sensitive chemotherapeutic alkylating agent is provided in the carrier. In another embodiment, the pH sensitive chemotherapeutic alkylating agent is provided in the carrier and not in, or encapsulated by, the polymer. In another embodiment, the pH sensitive chemotherapeutic alkylating agent is provided in the carrier and/or encapsulated in the polymer.

The chemotherapeutic alkylating agent may be a pharmaceutically acceptable chemotherapeutic agent. The skilled person will be familiar with a large number of potential chemotherapeutic alkylating agents that may be suitable for controlled release in situ at a tissue site . For example, the alkylating agent may be in the form of a pro-drug or a precursor to a chemotherapeutic alkylating agent. The pro-drug may comprise a pH sensitive pro-drug. The precursor may comprise a pH sensitive precursor. The chemotherapeutic alkylating agent may be any pH sensitive chemotherapeutic alkylating agent, or pro-drug thereof. In particular, the term "chemotherapeutic alkylating agent" is also intended to refer to precursors thereof prior to their conversion to the active agent that is capable of alkylating DNA. A precursor may also include compounds having one or more intermediate compounds between conversion into the active agent that is capable of alkylating DNA. In one embodiment, the precursor, such as TMZ, is an immediate precursor, such as MTIC. In another embodiment, there is an intermediate precursor, such as MTIC, between the precursor, such as TMZ, and the active agent that is capable of alkylating DNA. The chemotherapeutic alkylating agent may comprise any agent selected from the group comprising ifosfamide (Ifex™); busulfan (Myleran™ or Busulfex™); cyclophosphamide (Cytoxan™); bendamustine (Treanda™ or Bendeka™); carboplatin (Paraplatin™); chlorambucil (Leukeran™); cyclophosphamide (Neosar™); cisplatin (Platinol™ or Platinol-AQ™); TMZ (Temodar™); melphalan (Alkeran™); carmustine (Gliadel™ or BiCNU™); lomustine (Gleostine™, CCNSB Capsules™, or CeeNU™); cyclophosphamide (Cytoxan Lyophilized); dacarbazine (DTIC-Dome™); oxaliplatin (Eloxatin™); melphalan (Evomela™); mechlorethamine (Mustargen™); thiotepa (Tepadina™ or Thioplex™); trabectedin (Yondelis™); streptozocin (Zanosar™), or a derivative thereof; or combinations thereof.

The chemotherapeutic alkylating agent may comprise an imidazotetrazine. For example, the chemotherapeutic alkylating agent may comprise or consist of TMZ, or an analogue thereof. An analogue of TMZ may comprise or consist of N3-propargyl.

The matrix formed by solidification of the polymer paste may be biodegradable. The matrix may be biocompatible. In one embodiment the matrix comprises a matrix of interlinked polymer particles, for example microparticles.

When the polymer paste solidifies (i.e. sets) to form a matrix it may change from a suspension or a deformable viscous state to a solid state in which the matrix formed is self-supporting and retains its shape. The matrix may be compressible without fracturing (for example a sponge or jelly consistency).

In one embodiment, the matrix of polymer particles is porous. The pores may be formed by voids within the polymer particles or by gaps between the polymer particles. In one embodiment, the pores are formed by voids within the polymer particles and by gaps between the polymer particles. The pores may be formed by the gaps, which are left between polymer particles used to form the matrix. The gaps between the polymer particles may not be filled with hydrogel. The matrix may have a pore volume (i.e. porosity) of at least about 30%. Alternatively, the matrix may have a pore volume (i.e. porosity) of at least about 40% or 50%. The pores may have an average diameter of about 100 microns. The matrix may have pores in the nanometre to millimetre range . The matrix may have pores of about 20 to about 50 microns, alternatively between about 50 and 120 microns. In one embodiment, the matrix has pores with an average size of 100 microns.

As the skilled man would appreciate, pore volume and pore size can be determined using microcomputer tomography (microCT) and/or scanning electron microscopy (SEM). For example, SEM can be carried out using a Philips 535M SEM instrument.

In one embodiment, the polymer paste for local chemotherapeutic drug delivery to a tissue site comprises PLGA:PEG polymer particles and/or PLGA polymer microparticles; a carrier having a pH of 6 or less, and TMZ, and optionally wherein the pH of the carrier is provided by an organic acid in the carrier. The pH may be between 2 and 6, alternatively between 2 and 4, alternatively about pH3.

According to another aspect of the present invention, there is provided a matrix formed from the polymer paste according to the invention herein.

According to another aspect of the present invention, there is provided a matrix for local delivery of a chemotherapeutic agent to a tissue, wherein the matrix is in the form of interlinked polymer particles, and

wherein the matrix has an acidic pH of less than 6, or an alkali pH of 8 or more.

The matrix may comprise a carrier surrounding and/or amongst the matrix, wherein the carrier has an acidic pH of less than 6 or an alkali pH of 8 or more. The carrier may comprise an organic acid, for example to provide the acidic pH.

The matrix may be shaped into the shape of the tissue cavity. The matrix may be spread onto, and at least partially take the shape of, the walls of the tissue cavity. The matrix may not fill the void of the cavity, for example, the matrix may line the cavity walls, but not fill the centre . The skilled person will understand that the dose of the chemotherapeutic alkylating agent (e .g. the amount in the polymer paste of the invention) may be dependent on the clinical context, such as the tumour mass, surgical resection cavity size and shape, the matrix implant size, or depending on the patient being treated. Therefore, in one embodiment the chemotherapeutic alkylating agent may be provided in the polymer paste at a dose of between about 10 and about 70% w/w (drug weight / polymer weight, w/w). In another embodiment the chemotherapeutic alkylating agent may be provided in the polymer paste at a dose of between about 20 and about 60% w/w (drug weight / polymer weight, w/w).

The chemotherapeutic alkylating agent may be released in an amount effective to have a desired chemotherapeutic effect. The local delivery of an agent may mean that the chemotherapeutic agent is released from the matrix into the environment around the matrix, for example surrounding tissues. The release of the chemotherapeutic alkylating agent into the tissue from the matrix may be a controlled release, such as a sustained release . In one embodiment, the agent release is sustained over a period at least 12 hours. In another embodiment, the agent release is sustained over a period at least 2 days. In another embodiment, the agent release is sustained over a period at least 5 days. In another embodiment, the agent release is sustained over a period at least 10 days. In another embodiment, the agent release is sustained over a period at least 2 weeks. The matrix may allow substantially zero or first order release rate of the chemotherapeutic agent from the matrix once the matrix has formed. A zero order release rate is a constant release of the agent over a defined time. The matrix may allow release of the chemotherapeutic alkylating agent for 4 weeks.

In one embodiment, the initial day 1 release is less than about 25 -33% of total loading. In another embodiment, the initial day 1 release is less than about 20% or less than about 10% or less than about 5%. This initial release may be followed by 1 - 10% release per day for about 7-28 days.

The release kinetics of the chemotherapeutic agent may be further modified by a number of means apparent to the skilled person. For example, adjustments to the PLGA copolymer ratio, end groups, molecular weight and/or particle size can all have an impact upon the release kinetics. The skilled person is able to determine by empirical studies appropriate combinations of these factors to provide the desired release profile.

Additional active agents may be provided in the polymer paste or matrix according to the invention. In one embodiment, the pH sensitive chemotherapeutic alkylating agent may be provided in combination with other active agents, such as other pH sensitive agents and/or anti-cancer therapeutic agents. The additional active agent may comprise or consist of a PARP inhibitor, such as olaparib. In another embodiment, the additional active agent may comprise or consist of a Topoisomerase II inhibitor, such as etoposide. In one embodiment, a combination of olaparib and TMZ is provided. In another embodiment, a combination of etoposide and TMZ is provided. In an embodiment where a combination of olaparib and TMZ is provided, the olaparib may be provided at a dose of between 0.4 μg/ml and 43 μg/ml, and optionally the TMZ may be provided at a dose of between about 58.25 μg/ml - 135.9 μg/ml. In another embodiment where a combination of olaparib and TMZ is provided, the olaparib may be provided at a dose of between 0.4 μg/ml and 43 μg/ml, and optionally the TMZ may be provided at a dose of about 97 μg/ml. In an embodiment where a combination of etoposide and TMZ is provided, the etoposide may be provided at a dose of between 0.2 μg/ml and 59 μg/ml, and optionally the TMZ may be provided at a dose of between about 58.25 μg/ml - 135.9 μg/ml. In another embodiment where a combination of etoposide and TMZ is provided, the etoposide may be provided at a dose of between 0.2 μg/ml and 59 μg/ml, and optionally the TMZ may be provided at a dose of between about 58.25 μg/ml - 135.9 μg/ml, and optionally the TMZ may be provided at a dose of about 97 μg/ml.

According to another aspect of the present invention, there is provided a method of treatment for cancer in a subject comprising the local administration of the polymer paste according to the invention to cancerous tissue or potentially cancerous tissue in the subject.

According to another aspect of the present invention, there is provided the polymer paste according to the invention for use for local administration to treat or prevent cancer in a subject. According to a further aspect of the present invention, there is provided the polymer paste according to the invention for use in treating or preventing cancer. The polymer paste may be intended to be administered locally. In one embodiment, the cancer is brain cancer, such as glioblastoma. In one embodiment the cancer comprises malignant glioma or recurrent glioblastoma multiforme. In one embodiment, the cancer comprises CNS tumour, such as children' s CNS tumour. For example, the cancer may comprise ependymoma, medulloblastoma, primitive neuroectodermal tumour (PNECT) of the CNS, and former CNS PNETs.

In another embodiment, the cancer may comprise breast cancer, pancreatic cancer, or liver cancer.

The subject may be any patient with cancer. The subject may be a child, for example under 16 years of age. The child may be under 10 years of age. In another embodiment, the subject may be an adult.

The subject may be post-operative, having undergone surgery to remove cancerous, pre-cancerous tissue, or suspected cancerous tissue .

The administration of the polymer paste may be into a post-operative cavity in the tissue following surgery. In one embodiment, the administration of the polymer paste is into a cavity in the tissue following surgical removal of cancerous, pre-cancerous tissue, or suspected cancerous tissue. In one embodiment, the polymer paste is applied around the wall of a cavity in tissue following surgical removal of cancerous, precancerous tissue, or suspected cancerous tissue . The polymer paste may not be applied to substantially fill the void of a cavity in tissue following surgical removal of cancerous, pre-cancerous tissue, or suspected cancerous tissue . In a further aspect, the invention provides a method of controlled local tissue delivery of a pH sensitive chemotherapeutic alkylating agent to a subject, the method comprising providing a polymer paste comprising discrete polymer particles and a carrier, wherein the chemotherapeutic alkylating agent is located within the discrete particles and/or carrier; administering the polymer paste to tissue of the subject; allowing the polymer paste to solidify into a matrix in the subject; and allowing the chemotherapeutic agent contained within the matrix to be released into the tissue of the subject at the site of administration,

wherein the polymer paste has an acidic pH of 6 or less or an alkali pH of 8 or more.

The polymer paste may have a pH of 5.5 or less. The polymer paste may have a pH of 5 or less. The polymer paste may have a pH of 4.5 or less. The polymer paste may have a pH of 4 or less. The polymer paste may have a pH of 3.5 or less. The polymer paste may have a pH of 3 or less. The polymer paste may have a pH of about 3. In another embodiment, the polymer paste may have a pH of 8 or more. In another embodiment, the polymer paste may have a pH of 9 or more. In another embodiment, the polymer paste may have a pH of 10 or more.

The half-life of the chemotherapeutic alkylating agent may be at least 10-fold greater at pH 4 or less, relative to the half-life at pH7. The half-life of the chemotherapeutic alkylating agent may be at least 10-fold greater at pH 3.5 or less, relative to the half- life at pH7. The half-life of the chemotherapeutic alkylating agent may be at least 10- fold greater at pH 3 or less, relative to the half-life at pH7. The half-life of the chemotherapeutic alkylating agent may be at least 10-fold greater at pH of between 2 and 4, relative to the half-life at pH7.

The chemotherapeutic alkylating agent may be released in an amount effective to have a desired chemotherapeutic effect. The local delivery of an agent may mean that the chemotherapeutic agent is released from the matrix into the environment around the matrix, for example surrounding tissues. The release of the chemotherapeutic alkylating agent into the tissue from the matrix may be a sustained release. In one embodiment, the agent release is sustained over a period at least 12 hours. In another embodiment, the agent release is sustained over a period at least 2 days. In another embodiment, the agent release is sustained over a period at least 5 days. In another embodiment, the agent release is sustained over a period at least 10 days. In another embodiment, the agent release is sustained over a period at least 2 weeks. The matrix may allow substantially zero or first order release rate of the chemotherapeutic agent from the matrix once the matrix has formed. A zero order release rate is a constant release of the agent over a defined time . The chemotherapeutic agent may be released by one or more of: diffusion of the chemotherapeutic agent through pores in the matrix; degradation of the matrix leading to increased porosity and improved outflow of fluid carrying the chemotherapeutic agent; and physical release of chemotherapeutic agent from the matrix. It is within the abilities of the skilled man to appreciate that the size and/or number of the pores in the matrix and/or the rate of degradation of the matrix can readily be selected by appropriate choice of starting material so as to achieve the desired rate of release. For example, the rate of release may be controlled by controlling the size and/or number of the pores in the matrix and/or the rate of degradation of the matrix. Other factors that can be controlled are the concentration of any suspending agent included in the carrier, the viscosity or physiochemical properties of the polymer paste, and the choice of carrier.

The chemotherapeutic alkylating agent may be added to the polymer paste immediately prior to administration to the subject.

According to another aspect, the invention provides a kit for providing a polymer paste for local delivery of a pH sensitive chemotherapeutic alkylating agent to a tissue site, the kit comprising

a polymer;

a liquid carrier

a pH sensitive chemotherapeutic alkylating agent,

wherein the polymer and carrier are capable of forming a polymer paste upon mixing, and the polymer paste is capable of solidifying into a matrix in situ at the tissue site.

The resulting polymer paste may have an acidic pH of 6 or less, or an alkali pH of 8 or more. In one embodiment, the carrier may have an acidic pH of 6 or less, or an alkali pH of 8 or more.

The kit may comprise the polymer and the carrier in separate containers. The pH sensitive chemotherapeutic alkylating agent may be provided pre-mixed in the carrier or separate. In one embodiment, the pH sensitive chemotherapeutic alkylating agent is provided in the form of a solid. The kit may comprise a spatula for use in applying the polymer paste. The term "pH sensitive" used in relation to a chemotherapeutic alkylating agent is understood to mean that the agent has decreased stability, in other words a decreased half-life, at physiological (i.e . neutral) pH relative to either a higher alkaline pH or a lower acidic pH (dependent on the chosen agent). For example, the half-life of the chemotherapeutic alkylating agent may be at least 10-fold greater at pH 4 or less, relative to the half-life at pH7.

The term "malleable" may be used interchangeably with "mouldable" and is understood to mean that the polymer paste may be capable of being shaped or moulded in situ, for example prior to solidification. The term "malleable" may include a paste or putty.

The term "paste" is understood to include a particulate polymer paste that is flowable and capable of being manipulated in shape by a spatula, and would take the form of a container or cavity, but would not immediately disperse from the site of its application, for example if submerged in water it may not immediately disperse or mix with the water. The term "putty" is understood to mean a solid material that is malleable or otherwise mouldable, such that is capable of being shaped and re-shaped prior to solidification, for example to take up the shape of a cavity. It may be malleable by hand.

The term "injectable" is understood to mean that the material is capable of being loaded into a syringe barrel and pushed through a nozzle aperture under normal human hand pressure.

The mechanical properties of a paste may be characterized by rheology (AR200 advanced Rheometer, TA Instruments).

The term "biocompatible" is understood to include non-toxic to the human or animal body. To be biocompatible, the polymer paste may not cause an immune response.

The term "biodegradeable" is understood to include the ability to breakdown over time in the tissue or body of a human or animal. The time for complete degradation may be at least 1 week, at least 1 month, at least 2 months, at least 6 months, or at least 12 months. The time for complete degradation may be no more than 2 months. The time for complete degradation may be no more than 1 month. The term "matrix" is understood to mean a solid mass of material having a 3 - dimensional structure. In embodiments of the invention, the matrix may be porous, having interconnected pores or gaps.

The term "polymer paste" is intended to refer to a composition that is capable of forming a matrix, i.e. a pre-matrix material. For example the matrix material may comprise a composition that is capable of solidifying into a matrix. The matrix material itself may or may not have a structure of a matrix until the matrix material has formed the matrix according to the methods herein. Reference to "a polymer paste that is capable of forming a matrix" may include the capability to form a matrix with no further intervention/process steps or components. In an alternative embodiment, reference to "a polymer paste that is capable of forming a matrix" may include the capability to form a matrix following further intervention/process steps and/or following addition of setting agents. The term "room temperature" is intended to refer to a temperature of from about 15°C to about 25°C, such as from about 20°C to about 25°C.

The term "solidifying herein is intended to refer to the act of sintering or otherwise fixing, the matrix material into a solid scaffold. The solidification may be actively promoted, for example by a change in conditions, such as temperature and/or pressure. In one embodiment, solidification is achieved by sintering. In one embodiment, solidification is achieved by addition of a setting agent and/or condition. In another embodiment, the solidification of the matrix-forming material into a solid matrix may be a passive step, for example the particles of the matrix-forming material may spontaneously interlink upon contact. This may be immediate interlinking upon contact, or for example over a period of time. In one embodiment, the solidification may be facilitated by leaching of plasticiser from polymer particles that may make up the matrix-forming material. Solidification may be facilitated by administration/ implantation to a body or tissue . The term "solidifying", "solidification" or "solidify" herein is intended to refer to the change of state from a flowable state (for example, that may take the shape of a receptacle) to a non-flowable state where, for example, the polymers or polymer particles of the matrix-forming material are interconnected and set in position relative to each other. For the purposes of the present invention a putty or gel-like material may be considered a solidified material. The term "flowable" may include liquid or solid particles, pellets or powder that are not interconnected and are capable of flowing. A "plasticiser" is a substance typically incorporated into a polymer to increase its flexibility, softness, distensibility or workability. Plasticizers can weaken the bonds holding the polymer molecules together and can have an effect on thermal and/or mechanical properties. The plasticiser may be a pharmaceutically acceptable plasticiser. The plasticiser may be a polymer solvent.

The terms "inter-link" or "interlinking" are intended to refer to polymers or polymer particles becoming physically connected and held together (i.e. interacting and sticking together). Inter-linking may be achieved by covalent, non-covalent, electrostatic, ionic, adhesive, cohesive or entanglement interactions between the polymer particles or polymer components of the matrix-forming material. The polymer or polymer particles of the matrix may be inter-linked.

The skilled person will understand that optional features of one embodiment or aspect of the invention may be applicable, where appropriate, to other embodiments or aspects of the invention.

Embodiments of the invention will now be described in more detail, by way of example only, with reference to the accompanying drawings. Figure 1 : Schematic illustration of PLGA/PEG microparticulate chemotherapy paste.

Figure 2 : Ex vivo proof-of-concept demonstrating neurosurgical application of PLGA/PEG chemotherapy paste. Image taken after polymer solidification showing close proximity to juvenile ovine brain tissue and retention within a pseudo-resection cavity lining.

Figure 3: Early proof-of-concept and clinical compatibility of PLGA/PEG matrices. (A) In vitro dual simultaneous release of methotrexate (MTX) and etoposide (ETOP) from PLGA/PEG matrices. Formulation 1 represents mixing MTX/ETOP and polymer microparticles within a saline carrier solution. Formulation 2 dampens the drug release burst as MTX/ETOP is encapsulated inside PLGA/PEG microspheres, offering an element of 'controlled drug release' . (B) Polymer can be distinguished from brain tissue in MRI (left) and

(C) CT (right) scans using an ex vivo juvenile sheep model. White arrows indicate pseudo resection cavity filled with polymer and black arrow indicates cavity lined with polymer (the more clinically-relevant scenario). (D) Efficacious ETOP release from PLGA/PEG determined by reduction in GBM bioluminescence (as a proxy for tumour size) in a mouse flank xenograft

(right) relative to untreated control (left).

Figure 4 : (A) In vitro release of TMZ from PLGA/PEG matrices. Cumulative release of TMZ into water as a percentage of the 500 μg loaded per matrix over 10 days. Matrices were prepared by using the modified formulation where

0.05% lactic acid is used as the carrier solution. Graph shows an initial burst release phase followed by sustained release of TMZ for 7 days. (B) Mass spectrum of 24-hour release from PLGA/PEG TMZ formulation showing stable preservation of the TMZ molecular ion at m/z 195 (arrow) (C) Chemical structure of TMZ and N3-propargyl analogue. The TMZ analogue N3 - propargyl was synthesised by substituting N3-methyl with propargyl. R = N3 mono-functional alkylating groups.

Figure 5 : TMZ, ETOP and Olaparib (OLA) tolerability in adult human GBM subcutaneous mouse xenografts. Blank PLGA/PEG was well tolerated over

100 days after implantation at day 3 (d3). A dose escalation of TMZ polymers revealed toxicity (rapid loss of animal weight) at 30% weight/weight (w/w), but well tolerated doses at 20% and 15% w/w. 50% w/w ETOP and OLA polymers were well tolerated in all animals. Data represent the mean of 3 mice per arm. d = day of PLGA/PEG blank or drug-containing implant. Figure 6: Tolerability and efficacy of PLGA/PEG/TMZ/ETOP in 9L syngeneic orthotopic gliomas. (Top) PLGA/PEG/TMZ/ETOP is moulded to a surgical resection cavity. (A) Kaplan-Meier survival plot for rats implanted with 9L gliosarcoma 5 days prior to surgical resection (Experiment 1) with a significant overall survival advantage for PLGA/PEG/TMZ/ETOP paste over sham surgery (49 vs. 14 days; p < 0.001), blank paste (49 vs. 14 days; p < 0.001) or oral TMZ (49 vs. 33 days; p < 0.004). (B) Kaplan-Meier survival plot for rats implanted with 9L gliosarcoma on the day of surgical resection (Experiment 2) with a significant overall survival advantage for PLGA/PEG/TMZ/ETOP paste over sham surgery or blank paste. (C) x4 H&E micrograph of animal treated with surgery alone showing extensive tumour recurrence (star). (D) x4 micrograph of animal treated with identical surgery plus PLGA/PEG/TMZ/ETOP paste with a gliotic scar (star) at the tumour site but no visible tumour recurrence. (E-F) No weight loss observed in

PLGA/PEG/TMZ/ETOP rats from Experiments 1 or 2. High dose (20% w/w TMZ / 50% w/w ETOPj; low dose (10% w/w TMZ / 25% w/w ETOPj.

Figure 7: Application of LESA-MS to measure brain drug distribution. (A) Schematic depiction of LESA-MS . Under robotic control, a liquid micro- junction of an extraction solvent is formed between the sample tip and surface of an organotypic rat brain slice . Drug molecules released from PLGA/PEG are extracted from the surface to the solvent at different spatial locations. (B) Solvent containing drug molecules and brain tissue analytes are sprayed through a nano-electrospray chip and detected by a mass spectrometer. (C) A cortical brain-slice showing 8 laterally distributed locations 2 mm apart is sampled by LESA-MS . (D) (Top) Total mass spectrum obtained by LESA-MS on cortical brain slices ex vivo whereby native tissue analytes and the carboplatin (CRB) target molecular ion is detected from one brain slice region as an example; (Bottom) Tandem MS/MS fragmentation of the molecular ion of CRB enables definitive label-free identification of the drug based upon a molecular fingerprint.

Figure 8 : In vivo efficacy of temozolomide(TMZ)-delivered by PLGA/PEG in a rat brain cancer model. Kaplan-Meier overall survival plots of F344 rats that were implanted with a brain tumour (9L) and either given no treatment (control; blue), surgery + oral TMZ (S/poT; green) or surgery + PLGA/PEG/TMZ (S/PT; yellow) . Animals that received surgery and PLGA/PEG delivered TMZ (S/PT, n=7) had a relatively increased mean overall survival of 3 1.0 days, with 14.3 % of animals deemed long-term survivors (P <

0.0001 vs. animals that received surgery and oral TMZ) .

Figure 9 : In vivo efficacy of combined temozolomide (TMZ) and etoposide (ETOP)-delivered by PLGA/PEG in a rat brain cancer model. Kaplan-Meier overall survival plots of F344 rats that were implanted with a brain tumour

(9L) and either given no treatment (control; blue), surgery + PLGA/PEG/TMZ/ETOP (S/PT&E; green), surgery + PLGA/PEG/TMZ/ETOP + radiotherapy (S/PT&E/R; yellow) or surgery + radiotherapy (S/R; purple). Animals that received surgery and PLGA/PEG delivered TMZ/ETOP with adjuvant radiotherapy (S/P/T&E/R, n=7) had an increased mean survival of

76.8 days relative to animals that received surgery and PLGA/PEG delivered TMZ/ETOP or surgery and radiotherapy (S/R, n=7) (P < 0.0001 vs. both groups). Figure 10: Summary of mean and median overall survival a rat brain cancers .

Long-term survivors are evident in PLGA/PEG treatment arms, relative to control arms, where PLGA/PEG-delivered TMZ/ETOP with adjuvant radiotherapy resulted in the highest relative percentage (57. 1%) of long-term survivors. Group labels - T, l Omg temozolomide; E, 25mg etoposide; S, surgery; R, irradiation ( l OGy); poT, oral temozolomide (50mg/kg/day for 5 days).

Figure 11 : Histology of rat brain tissue after 50 days post-PLGA/PEG- delivered TMZ/ETOP. H&E staining: (A) High dose PLGA/PEG/TMZ/ETOP showing gliotic scarring (denoted by *) but no recurrent tumour. (B-D) Blank

PLGA/PEG paste, oral TMZ and sham surgery respectively, show extensive tumour recurrence (denoted by *). Ki67 (proliferation marker) immunohistochemistry: (E) High dose PLGA/PEG/TMZ/ETOP showing site of surgical resection with no visible proliferative cells, evidence of a lack of tumour recurrence. (F-H) Blank PLGA/PEG paste, oral TMZ and sham surgery respectively, reveals significant numbers of dividing cells and invading cells (brown nuclear staining), evidence of tumour recurrence .

Examples

Materials and Methods:

Ex vivo surgical application of PLGA/PEG (Figure 2)

Cadaver sheep brains were sourced from a local abattoir after permission was granted to use these animal parts (C Brumpton Butchers Ltd, Nottingham). Heads were fixed in a vice and bilateral skin and muscle flaps raised. Three burrholes were performed with a Hudson brace on each fronto-temporal region of the cranium and joined with a Gigli saw to raise craniotomies. The dura was incised and flapped back, and secured with vicryl stay sutures. Incisions were made through the pia and the brain parenchyma excised to give a cavity of dimensions 2.5 x 2.5 x 2.5cm. PLGA/PEG blended microparticles were mixed with PBS in a 1 :0.6 ratio to form polymer-based paste and applied to the lining of the pseudo-resection cavity.

In vitro PLGA/PEG particle production (Figure 3)

Thermosensitive particles were fabricated from blends of 53kDa P_DL LGA (85 : 15 DLG 4CA) (Evonik Industries) and PEG 400 (Sigma Aldrich, UK) as previously described (ref 7). Briefly, a mixture of 93.5%: 6.5 % PLGA/PEG (w/v) was blended at 80-90°C on a hotplate, mixed and allowed to cool. Cooled polymer was then ground into particles and sieved to obtain the 100-200μιη particle size fraction.

Matrix preparation for in vitro release studies (Figure 3)

200 mg of PLGA/PEG particles were mixed with 160 μΐ saline carrier containing 1.5 mg of either Methotrexate (MTX) (Sigma, UK), Etoposide (ETOP) (Sigma, UK) or MTX and ETOP. The amount of solution was in the ratio of 1 : 0.8 so 160 μΐ of saline solution was used to form the paste. Particle paste was then formed into 3 cylindrical PTFE molds of 4 mm height and 6mm in diameter and incubated for 2 hours at 37 °C in a humidified incubator. The resulting matrices contained 500 μg of each drug each. In vitro release assay (Figure 3)

Triplicate scaffolds loaded with MTX and ETOP were placed in 1 mL of distilled water and incubated at 37 °C. At given time intervals the 1 mL pf water was removed, retained and replaced with fresh distilled water. The retained fraction was either assayed using HPLC and UV-Vis spectrophotometry at 295 nm and 324 nm for MTX and ETOP respectively, using a NanoDrop (ThermoFisher, UK). Non-drug loaded matrices containing saline carrier alone were used to test background absorbance readings. MRI and CT scanning of ex vivo brain (Figure 3)

MR imaging was performed using a clinical 3 T Achieva MR scanner (Philips Medical, Best, The Netherlands) with the specimen placed inside the 8 channel receive-only head coil. Routine fat-suppressed 3D turbo spin echo Tl- and T2 -weighted whole brain imaging was performed with acquisition resolution of lxlxl mm, 192x192x160 matrix, echo train length of 133, echo time of 262 ms, repetition time of 2500 ms, and 464 s overall scan time. The CT scans were acquired using an adult head protocol on a clinical Mx8000 IDT 16 scanner (Philips Medical, Best, The Netherlands). 144 slices, 1.5 mm thick, were acquired at 120 kV with 512x512 matrix and 0.45 mm in-pixel pixel size. In vivo etoposide release from PLGA/PEG matrices (Figure 3)

This study was approved by the University of Nottingham local Ethical Review Committee and granted by the UK Home Office (License No. PPL 40/3559), after consideration of the justification of animal research and good animal welfare. Six 4-6 week old male MF- 1 nude mice (3 mice per arm) were maintained under standard conditions as detailed in the UK Home Office Animals (Scientific Procedures) Act 1986 and studies conducted and reported in compliance with the 2010 NC3R ARRIVE guidelines. Animals U87 GBM cells tagged with a bioluminescent marker (DLuX) were injected subcutaneously into the left flank and the tumour grown for 15 days whilst monitoring using the IVIS Spectrum bioluminescent imaging system (PerkinElmer, UK). Mice with satisfactory tumour take and growth rates underwent partial tumour resection. The previous flank incision was re-opened and a biopsy punch/fine suction tip used to resect tumour back to the tumour/tissue interface, thus mimicking the surgical technique utilized in human patients undergoing comparable surgery for GBM. Etoposide-loaded PLGA/PEG matrices (experimental arm) or blank PLGA/PEG matrices (control arm) were moulded around the resection cavity. Animals were weighed daily by an experienced technician, any adverse effects noted, and sacrificed using cervical dislocation once their clinical condition deteriorated, in order to ameliorate suffering. Mice were sacrificed 3 days post-implantation and tumour tissue sectioned prior to staining with hematoxylin and eosin or glial fibrillary acidic protein (GFAP) (anti-GFAP (Abeam, ab726; 1 : 1000) .

LCMS analysis of TMZ (Figure 4)

200 mg of PLGA/PEG particles were mixed with a solution of 0.05% (w/v) Lactic Acid (Sigma, UK) containing 1.5 mg of TMZ (Sigma, UK) . The amount of solution was in the ratio of 1 : 0.8 so 160 μΐ of 0.05% (w/v) Lactic Acid solution was used to form the paste . Particle paste was then formed into 3 cylindrical PTFE molds of 4 mm height and 6mm in diameter and incubated for 2 hours at 37 °C in a humidified incubator. The resulting matrices contained 500 μg of each drug each. Chromatographic separation of TMZ was achieved using a Prominence HPLC (Shimadzu, Kyoto, Japan) with a Kinetex C I 8 50mm x 4.6mm 2.6μιη and a SecurityGuard cartridge C 18 3mm guard column (Phenomenex, California, USA) maintained at 30 °C. Analytes were eluted with HPLC grade (Sigma-Aldrich) mobile phases comprising 0.1 % aqueous formic acid (A) and 0. 1 % formic acid in acetonitrile (B) . The flow rate was 0.5 mL/min and the mobile phase system consisted of a starting condition of 5% buffer B, maintained for 1.5 minutes before increasing to 100% B at 2.5 minutes before returning to 5% B at 3 minutes. A final re-equilibration duration of 2 minutes at 5%B was employed giving a total run time of 5 minutes. An API4000 triple quadrupole LC-MS/MS (Applied Biosystems, California, USA) was used for analysis with electrospray ionisation performed in positive ion mode with the following source settings: curtain gas, 20; ion source gas 1 , 50; ion source gas 2, 40; ion spray voltage, 5500; collision gas, 6; entrance potential, 10; ionisation temperature, 500°C. Detection of TMZ was achieved using the transition m/z 195.088- > 138.0 in positive electrospray MRM mode with a dwell time of 150ms and the following mass spectrometer settings: Declustering Potential 5 1 , Entrance Potential 10, Collision Energy 13, Collision Cell Exit Potential 8.

TMZ sample extraction and analysis (Figure 4)

For analysis, 50μ1 sample was added to 450μ1 ethyl acetate and the resulting precipitate was vortexed for 10 seconds followed by centrifugation at 4°C for 3 minutes at 6000g. 300μ1 supernatant was then removed and dried down to residue under a steady stream of nitrogen gas. Samples were re-constituted in 150μ1 of 50 : 50 HPLC mobile phase A and B, before an injection of Ι ΟμΙ for analysis. A standard curve over the range 0.44 - 500ng/ml TMZ in matched matrix was prepared fresh on each day of analysis.

In vivo tolerabilitv of PLGA/PEG/TMZ/ETOP (Figure 5)

1 x 10^s U87 GBM cells were implanted subcutaneously in nude mice to generate xenografts. Tumour growth was monitored via bioluminescence using an IVIS scanner. Once tumours were large enough for partial resection, tumour was excised and PLGA/PEG paste loaded with 15-30% w/w TMZ and 50% w/w ETOP was applied to the surgical resection lining. Body weight was measured 2-3 times weekly over a period of 100 days and plotted against control animals which had sham surgery and blank PLGA/PEG paste . In vivo efficacy of PLGA/PEG/TMZ/ETOP (Figure 6)

The Johns Hopkins animal facilities are in compliance with the Animal Welfare Act regulations and Public Health Service Policy (see supporting ethics letter) and adhere to the UK Home Office Animals (Scientific Procedures) Act Amended Regulations 2012 and 2010 NC3R ARRIVE guidelines. Syngeneic HGG tumours (9L) were implanted into the brains of female Fischer 344 rats, 5-days prior to surgery (Group 1 ; Figure 6A and E) or concurrent with surgery (Group 2; Figure 6B and 6F). Oral TMZ in control arms was administered at 50mg/kg/day for 5 days, mimicking the human dosing regimen. Group 1 rats were randomly divided into the following arms : untreated (sham surgery) (n=2); surgery + oral TMZ (n=2); surgery + 50 mg blank PLGA/PEG paste (n=6); surgery + 50 mg PLGA/PEG containing 20% w/w TMZ ( 10 mg), 50% w/w ETOP (25 mg) (n=4); Surgery + 50 mg PLGA/PEG containing 10% w/w TMZ (5 mg), 25% w/w ETOP ( 12.5 mg) (n=4). Group 2 rats were randomly divided into the following arms: untreated (sham surgery) (n=2); surgery + 50 mg blank PLGA/PEG paste (n=6); surgery + 50 mg PLGA/PEG containing 20% w/w TMZ ( 10 mg), 50% w/w ETOP (25 mg) (n=4); Surgery + 50 mg PLGA/PEG containing 10% w/w TMZ (5 mg), 25% w/w ETOP ( 12.5 mg) (n=4). An overall increase in survival days of > 50% relative to controls was considered attributable to a therapeutic effect. Animals were monitored for up to 50 days post-surgery. Detection of diffused drug ex vivo using surface extraction mass spectrometry (Figure n

PLGA/PEG loaded with carboplatin was placed in the centre region of an organotypic rat coronal brain slice. Under robotic control, a liquid micro-junction of an extraction solvent was formed between the sample tip and surface of the brain slice. Carboplatin molecules released from PLGA/PEG were extracted from the surface to the solvent at 8 laterally distributed locations 2 mm apart. Solvent containing carboplatin molecules and brain tissue analytes were sprayed through a nano-electrospray chip and detected by a mass spectrometer. Tandem MS/MS fragmentation of the molecular ion of carboplatin enabled definitive label-free identification of the drug based upon a molecular fingerprint.

Discussion of results: Ex vivo proof-of-concept demonstrating neurosurgical application of PLGA/PEG chemotherapy paste (Figure 2):

After conducting a craniotomy of an ovine skull, PLGA/PEG paste (upon immediate mixing of PLGA/PEG microparticles and a saline carrier solution) was applied to a pseudo-resection surgical cavity using a simple spatula. This proof-of-concept demonstrates the clinical utility of rapidly applying the drug delivery system in a manner that will require little training for the neurosurgeon and minimal operating time. The image specifically shows PLGA/PEG paste after 15 minutes at 37°C (body temperature), where the polymer has solidified (sintered), taking the shape of the surgical cavity lining.

Early proof-of-concept and clinical compatibility of PLGA/PEG matrices (Figure 3) :

To demonstrate the capability of dual drug release in a controlled manner, methotrexate (MTX) and etoposide (ETOP) were mixed with PLGA/PEG microparticles (Formulation 1) or encapsulated within PLGA/PEG microspheres and mixed with PLGA/PEG microparticles (Formulation 2). Either formulation was placed in PBS solution at 37°, sampled at regular intervals, with absorbance of drug measured using HPLC and UV spectrometry. Formulation 1 results in a rapid burst release followed by near zero-order release of each drug, whereas Formulation 2 eliminates a burst phase of drug release and results in a relatively gradual zero-order release from commencement of release (Figure 3A). The result confirms the advantage of PLGA/PEG over delivery systems such as Gliadel®, whereby multiple drugs can be released simultaneously, particularly applicable to the next-generation of chemotherapy trials which will likely be multi-agent.

To establish whether PLGA/PEG interferes with MRI- and CT-based brain scans by causing image artifacts that obscure visualization of brain parenchyma and thereby potentially hampering identification of a recurrent tumour, an ovine head containing one polymer-filled and one polymer-lined pseudo-resection cavity was scanned ex vivo under standard clinical procedure. Cavities filled and lined with PLGA/PEG are distinguishable from the surrounding brain parenchyma using standard CT scanning. Similarly, cavities filled with PLGA/PEG are distinguishable from surrounding brain parenchyma using T2- and T l - weighted MRI scans. Edges of the cavity are clearly defined with no additional image artefacts observed from the PLGA/PEG, indicating insignificant spatial distortion and good contrast with brain parenchyma on T2 and T l MR. Therefore, application of PLGA/PEG matrices does not interfere with clinical scanning modalities used as standard procedures for the detection of brain tumours (Figure 3B-C).

Luciferase-tagged U87 GBM cells were used to generate subcutaneous xenografts in nude mice . ETOP-loaded polymer was moulded around a flank GBM resection cavity after performing partial tumour resection. Mice were sacrificed 3 days after implantation of the drug-loaded polymer to demonstrate proof-of-concept for in vivo drug release and gauge short-term drug diffusion distance. Treatment animals reveal a marked reduction in bioluminescence (proportional to tumour density) relative to animals treated with blank PLGA/PEG paste . The result indirectly confirms release of ETOP from PLGA/PEG paste in vivo and reveals the potential efficacy of the drug delivery system.

In vitro release of TMZ from PLGA/PEG matrices (Figure 4) :

The incorporation of 0.05% lactic acid in the carrier solution mixed with TMZ and PLGA/PEG microparticles, overcomes the instability of TMZ . Here, after a rapid burst phase of release, TMZ continues to be detected after 7- 10 days of the release period, in contrast to similar studies using alternative biomaterials, where the release period is approximately 1 -2 days (Figure 4A). Using advanced HPLC analytical methods, we confirmed the specific presence of the TMZ molecular ion with a m/z (mass/charge) fingerprint of 195 (Figure 4B). TMZ analogues have been synthesised which may potentially be efficacious against tumours which are TMZ-resistant; one such example is N3-propargyl which does not however cross the blood-brain-barrier and therefore makes it particularly suitable for localised drug delivery using PLGA/PEG paste.

TMZ. ETOP and Olaparib (OLA) tolerability in adult human GBM subcutaneous mouse xenografts (Figure 5):

To demonstrate the tolerability of a lead drug formulation, PLGA/PEG paste loaded with either TMZ and ETOP or TMZ and OLA were administered locally to a surgical resection cavity in human GBM xenograft tumours implanted subcutaneously in nude immune deficient mice . Dose escalation revealed a maximum tolerated dose of 50% w/w (polymer weight/drug weight) for ETOP and OLA and 20% w/w TMZ over a period of 100 days. A TMZ dose of 30% w/w resulted in loss of body weight abruptly after day 50 (Figure 5).

Tolerability and efficacy of PLGA/PEG/TMZ/ETOP in 9L syngeneic orthotopic gliomas (Figure 6):

Kaplan-Meier survival plot for rats implanted with 9L gliosarcoma 5 days prior to surgical resection (Experiment 1 , Figure 6 A) reveal a significant overall survival benefit for PLGA/PEG/TMZ/ETOP paste over sham surgery (49 vs. 14 days; p < 0.001), blank paste (49 vs. 14 days; p < 0.001) or oral TMZ (49 vs. 33 days; p < 0.004). Kaplan-Meier survival plot for rats implanted with 9L gliosarcoma on the day of surgical resection (Experiment 2) similarly reveal a significant overall survival benefit for PLGA/PEG/TMZ/ETOP paste over sham surgery or blank paste. Brains sectioned from treatment rats show a high degree of tumour recurrence adjacent to the surgical site in animals treated with surgery alone (Figure 6C), whereas rats treated with PLGA/PEG/TMZ/ETOP adjuvant to surgery shows no evidence of tumour recurrence (Figure 6D). The observed efficacious results from Experiments 1 and 2 are concurrent with no adverse toxicity as determined by no loss of body weight (Figure 6E-F) and no neurological deficits. Thus, PLGA/PEG/TMZ/ETOP administered 5 days post tumour implant or administered at the same time of tumour implant, results in a survival advantage in rats bearing orthotopic gliomas. The study warrants comprehensively extending to include sufficient animals for robust statistical significance and to test any possible synergy with adjuvant radiotherapy, thus fully mimicking the clinical treatment regime.

Application of LESA-MS to measure brain drug distribution (Figure 7) :

To enable the detection of drugs released from PLGA/PEG paste which have penetrated the normal brain, liquid extraction surface analysis-mass spectrometry (LESA-MS) was adapted as proof-of-concept. Carboplatin drug molecules were released from PLGA/PEG onto rat organotypic coronal slices ex vivo and were extracted from the surface to the solvent at different spatial locations using a robotic arm. Solvent containing carboplatin molecules and brain tissue analytes were sprayed through a nano-electrospray chip and detected by a mass spectrometer to reveal the total mass spectrum. Tandem MS/MS fragmentation of the molecular ion of carboplatin enabled definitive label-free identification of the drug based upon a unique molecular fingerprint. This proof-of-concept method to detect a label-free drug will permit the retrospective measurement of drugs released from PLGA/PEG paste in future orthotopic studies in vivo, using sections of brain tissue from sacrificed animals. As the LESA-MS method does not require any radio or fluorescent labelling of a drug, an accurate physiological drug penetration profile is permitted and multiple drugs released from PLGA/PEG may potentially be discriminated. Long term in vivo study (Figures 8 to 1 1)

A long term in vivo animal study was undertaken to compare the efficacy of a PLGA/PEG paste according to the invention to both oral temozolomide and adjuvant radiotherapy. The study included looking at long-term animal survival rates, with animals being sacrificed at day 120 post-treatment. In this study a single dose of TMZ was administered, this corresponded to the maximum tolerated dose as determined in Figure 6, namely TMZ 20% w/w; ETOP 50% w/w.

In an aspect of this study F344 rats that were implanted with a brain tumour (9L) and then treated with one of the following treatment regimens: • no treatment (control; blue),

• surgery + oral temozolomide (S/poT; green), or

• surgery + PLGA/PEG/ temozolomide paste according to the invention (S/PT; yellow).

Figure 8 demonstrates the in vivo efficacy of temozolomide(TMZ)-delivered by PLGA/PEG in a rat brain cancer model. The Kaplan-Meier overall survival plots show that rats that received surgery and PLGA/PEG delivered TMZ (S/PT, n=7) had a relatively increased mean overall survival of 3 1.0 days, with 14.3% of animals deemed long-term survivors (P < 0.0001 vs. animals that received surgery and oral TMZ).

Figure 9 demonstrates the in vivo efficacy of combined temozolomide (TMZ) and etoposide (ETOP)-delivered by PLGA/PEG in a rat brain cancer model. In this study F344 rats were implanted with a brain tumour (9L) and then treated with one of the following treatment regimens:

• no treatment (control; blue),

• surgery + PLGA/PEG/ temozolomide/etoposide (S/PT&E; green),

• surgery + PLGA/PEG/ temozolomide / etoposide + radiotherapy (S/PT&E/R; yellow), or

• surgery + radiotherapy (S/R; purple).

The Kaplan-Meier overall survival plots show that rats that that received surgery and PLGA/PEG delivered temozolomide/etoposide with adjuvant radiotherapy (S/P/T&E/R, n=7) had an increased mean survival of 76.8 days relative to animals that received surgery and PLGA/PEG delivered temozolomide/etoposide or surgery and radiotherapy (S/R, n=7) (P < 0.0001 vs. both groups) .

The table in Figure 10 summarises the mean and median overall survival of the animals described with reference to Figures 8 and 9. Long-term survivors are evident in PLGA/PEG treatment arms, relative to control arms, where PLGA/PEG-delivered TMZ/ETOP with adjuvant radiotherapy (XRT) resulted in the highest relative percentage (57. 1 %) of long-term survivors. Group labels - T, l Omg temozolomide; E, 25mg etoposide; S, surgery; R, irradiation ( l OGy); poT, oral temozolomide (50mg/kg/day for 5 days). Finally, Figure 1 1 shows the histology of rat brain tissue 50 days post-PLGA/PEG- delivered TMZ/ETOP. H&E staining: Each of 1 1A to 1 1H shows the histology of rat brain tissue which had been implanted with a brain tumour (9L) 50 days after treatment with one of the following treatment regimens:

• (A) - high dose PLGA/PEG/TMZ/ETOP

• (B) - blank PLGA/PEG paste

• (C) - oral TMZ

• (D) - sham surgery

· (E) - high dose PLGA/PEG/TMZ/ETOP

• (F) - blank PLGA/PEG paste

• (G) - oral TMZ

• (H) - sham surgery Figures 1 1A to 1 1 D depict samples stained with H&E (Hematoxylin and Eosin). In Figure, 1 1A in which rats were treated with a high dose of PLGA/PEG/TMZ/ETOP, gliotic scarring (denoted by *) is observed but no recurrent tumour. Whereas in Figures 1 1B to 1 1D extensive tumour recurrence (denoted by *) is observed. Figures H E to 1 1H depict samples in which immunohistochemistry has been used to stain for the proliferation marker Ki67. In Figure 1 IE, in which rats were treated with a high dose of PLGA/PEG/TMZ/ETOP, the site of surgical resection can be seen but there are no visible proliferative cells, evidence of a lack of tumour recurrence. Whereas in Figures 1 IF to 1 1H a significant numbers of dividing cells and invading cells (brown nuclear staining) are observed, which is evidence of tumour recurrence.

Summary

We have developed a novel local chemotherapeutic drug delivery system utilising a biodegradable polymer formulation of PLGA/PEG, which can be pasted around the tumour cavity left behind after brain surgery. As the polymer is much like toothpaste, it is easy and quick for the brain surgeon to administer. PLGA/PEG paste solidifies only at the patient's body temperature, ensuring that it remains moulded to the tumour cavity and close to the remaining brain cancer cells. Chemotherapy drugs mixed into PLGA/PEG can be gradually released over several weeks, with the polymer completely degrading after around two months and safely removed by the body. Importantly, pH sensitive chemotherapy drugs such as alkylating agents can be delivered with this system due to the ability to alter the pH of the carrier solution. This protects such drugs from being degraded or otherwise rendered inactive in the tumour cavity, as they remain within the polymer matrix in a suitable pH environment until they are gradually released from the matrix over time.

Claims

1. A polymer paste for local chemotherapeutic drug delivery to a tissue site, the polymer paste comprising:

a polymer and a carrier; and

a pH sensitive chemotherapeutic alkylating agent,

2. The polymer paste according to claim 1 , wherein the polymer paste has an acidic pH of 6 or less when the chemotherapeutic alkylating agent is less stable at an alkali or neutral pH.

3. The polymer paste according to claim 1 , wherein the polymer paste has an alkali pH of 8 or more when the chemotherapeutic alkylating agent is less stable at an acidic or neutral pH.

4. The polymer paste according to any preceding claim, wherein the polymer paste comprises temperature-sensitive polymer particles that solidify into a matrix in situ at the tissue site of delivery.

5. The polymer paste according to any preceding claim, wherein the pH sensitive chemotherapeutic alkylating agent is provided in the carrier.

6. The polymer paste according to any preceding claim, wherein the solidification of the matrix from the polymer paste, once administered to a human or non-human animal, takes less than 1 hour.

7. The polymer paste according to any preceding claim, wherein the acidic pH is provided by an organic acid in the carrier.

8. The polymer paste according to claim 7, wherein the organic acid has a pKa of at least 3.

9. The polymer paste according to claim 7 or claim 8, wherein the organic acid comprises acetic acid or lactic acid.

10. The polymer paste according to any preceding claim, wherein the carrier is aqueous.

1 1. The polymer paste according to any preceding claim, wherein the polymer paste comprises from about 20% to about 80% polymer and from about 20% to about 80% carrier.

12. The polymer paste according to any preceding claim, wherein the polymer comprises or consists of polymer particles, optionally wherein the polymer particles are polymer microparticles.

13. The polymer paste according to any preceding claim, wherein the polymer particles are capable of interlinking and solidifying into a matrix by sintering.

14. The polymer paste according to claim 12 or 13, wherein the polymer particles are capable of spontaneously solidifying when applied into the tissue due to an increase in temperature post administration.

15. The polymer paste according to any preceding claim, wherein the polymer is temperature sensitive.

16. The polymer paste according to any of claims 12 to 15, wherein the polymer particles are not soluble in the carrier at a temperature of 37°C or less.

17. The polymer paste according to any preceding claim, wherein the polymer comprises or consists of one or more polymers selected from the group comprising poly (a-hydroxyacids) including poly (D,L-lactide-co-glycolide)(PLGA), poly D,L- lactic acid (PDLLA), polyethyleneimine (PEI), polylactic or polyglcolic acids, poly- lactide poly-glycolide copolymers, and poly-lactide poly-glycolide polyethylene glycol copolymers, polyethylene glycol (PEG), polyesters, poly (ε-caprolactone), poly (3-hydroxy-butyrate), poly (s-caproic acid), poly (p-dioxanone), poly (propylene fumarate), poly (ortho esters), polyol/diketene acetals addition polymers, polyanhydrides, poly (sebacic anhydride) (PSA), poly

(carboxybiscarboxyphenoxyphosphazene) (PCPP), poly [bis (p-carboxyphenoxy) methane] (PCPM), copolymers of SA, CPP and CPM, poly (amino acids), poly (pseudo amino acids), polyphosphazenes, derivatives of poly [(dichloro) phosphazene], poly [(organo) phosphazenes], polyphosphates, polyethylene glycol polypropylene block co-polymers, natural or synthetic polymers such as silk, elastin, chitin, chitosan, fibrin, fibrinogen, polysaccharides (including pectins), alginates, collagen, peptides, polypeptides or proteins, copolymers prepared from the monomers of any of these polymers, random blends of these polymers, any suitable polymer and mixtures or combinations thereof.

18. The polymer paste according to any preceding claim, wherein the polymer comprises or consists of polymer selected from the group comprising poly(a- hydroxyacids) such as poly lactic acid (PLA), polyglycolic acid (PGA), poly(D,L- lactide-co-glycolide)(PLGA), poly D, L-lactic acid (PDLLA), poly-lactide poly- glycolide copolymers, and combinations thereof.

19. The polymer paste according to any preceding claim, wherein the polymer comprises PLGA.

20. The polymer paste according to any preceding claim, wherein the polymer comprises or consists of a polymer blend of PLGA and PEG.

21. The polymer paste according to any preceding claim, wherein the polymer is biocompatible.

22. The polymer paste according to any preceding claim, wherein the polymer is biodegradable; or particles of the polymer are biodegradable .

23. The polymer paste according to any of claims 12 to 23, wherein the polymer particles are formed of a polymer or a polymer blend that has a glass transition temperature (Tg) either close to or just above body temperature, such as from about 30°C to 45°C.

24. The polymer paste according to any preceding claim, wherein the chemotherapeutic alkylating agent comprises any agent selected from the group comprising ifosfamide (Ifex™); busulfan (Myleran™ or Busulfex™); cyclophosphamide (Cytoxan™); bendamustine (Treanda™ or Bendeka™); carboplatin (Paraplatin™); chlorambucil (Leukeran™); cyclophosphamide (Neosar™); cisplatin (Platinol™ or Platinol-AQ™); TMZ (Temodar™); melphalan (Alkeran™); carmustine (Gliadel™ or BiCNU™); lomustine (Gleostine™, CCNSB Capsules™, or CeeNU™); cyclophosphamide (Cytoxan Lyophilized); dacarbazine (DTIC-Dome™); oxaliplatin (Eloxatin™); melphalan (Evomela™); mechlorethamine (Mustargen™); thiotepa (Tepadina™ or Thioplex™); trabectedin (Yondelis™); streptozocin (Zanosar™), or a derivative thereof; or combinations thereof.

25. The polymer paste according to any preceding claim, wherein the chemotherapeutic alkylating agent comprises an imidazotetrazine.

26. The polymer paste according to any preceding claim, wherein the chemotherapeutic alkylating agent comprises TMZ, or an analogue thereof.

27. The polymer paste according to claim 26, wherein the analogue of TMZ comprises N3-propargyl.

28. The polymer paste according to any preceding claim, wherein the matrix formed by the polymer particles is porous.

29. The polymer paste according to claim 28, wherein the pores are formed by voids within the polymer particles and/or by gaps between the polymer particles.

30. The polymer paste according to any preceding claim, wherein the chemotherapeutic alkylating agent is provided in the polymer paste at a dose of between about 10 and about 70% w/w (drug weight / polymer weight, w/w).

3 1. A matrix formed from the polymer paste according to any of claims 1 to 30.

32. A matrix for local delivery of a pH sensitive chemotherapeutic alkylating agent to a tissue, wherein the matrix is in the form of interlinked polymer particles, and wherein the matrix has an acidic pH of less than 6, or an alkali pH of 8 or more.

33. The matrix according to claim 32, comprising a pH sensitive chemotherapeutic alkylating agent; optionally at a dose of between about 10 and about 70% w/w.

34. The matrix according to claim 32 or 33, wherein the matrix is shaped in the shape of the walls of a tissue cavity.

35. The polymer paste according to any of claims 1 to 30, or a matrix according to any of claims 3 1 to 34, further comprising an additional active agent.

36. The polymer paste according to any of claims 1 to 30, or 35, or a matrix according to any of claims 3 1 to 35, further comprising a PARP inhibitor and/or a Topoisomerase II inhibitor.

37. A method of treatment for cancer in a subject comprising the local administration of the polymer paste according to any of claims 1 to 30 to cancerous tissue or potentially cancerous tissue in the subject.

38. The polymer paste according any of claims 1 to 30, 35 or 36, or a matrix according to any of claims 3 1 to 36 for use to treat or prevent cancer in a subject.

39. The method according to claim 37, or the polymer paste for the use according to claim 38, wherein the cancer is brain cancer, breast cancer, pancreatic cancer, or liver cancer.

40. The method according to claim 37 or 39, or the polymer paste for the use according to claim 38 or 39, wherein the subject is post-operative, having undergone surgery to remove cancerous, pre-cancerous tissue, or suspected cancerous tissue; or the subject is in surgery having cancerous, pre-cancerous tissue, or suspected cancerous tissue removed.

41. The method according to any of claims 37, 39 or 40, or the polymer paste for the use according to any of claims 38 to 40, wherein the administration of the polymer paste is into a cavity in the tissue following surgical removal of cancerous, precancerous tissue, or suspected cancerous tissue.

42. The method according to any of claims 37, 39 to 41 , or the polymer paste for the use according to any of claims 38 to 41 , wherein the polymer paste is applied around the wall of a cavity in tissue following surgical removal of cancerous, pre-cancerous tissue, or suspected cancerous tissue .

43. The method according to any of claims 37, 39 to 42, or the polymer paste for the use according to any of claims 38 to 42, wherein the polymer paste is not applied to substantially fill the void of a cavity in tissue following surgical removal of cancerous, pre-cancerous tissue, or suspected cancerous tissue.

44. A method of controlled local tissue delivery of a pH sensitive chemotherapeutic alkylating agent to a subject, the method comprising providing a polymer paste comprising discrete polymer particles and a carrier, wherein the chemotherapeutic alkylating agent is located within the discrete particles and/or carrier; administering the polymer paste to tissue of the subject; allowing the polymer paste to solidify into a matrix in the subject; and allowing the chemotherapeutic agent contained within the matrix to be released into the tissue of the subject at the site of administration,

45. A kit for providing a polymer paste for local chemotherapeutic drug delivery to a tissue site, the kit comprising

a polymer;

a liquid carrier

a pH sensitive chemotherapeutic alkylating agent,

46. The kit according to claim 45, wherein the carrier has an acidic pH of 6 or less, or an alkali pH of 8 or more .

47. The kit according to claims 45 or 46, wherein the polymer and the carrier are provided in separate containers.

48. The kit according to any of claims 45 to 47, wherein the pH sensitive chemotherapeutic alkylating agent is provided pre-mixed in the carrier.

49. The kit according to any of claims 45 to 48, wherein the pH sensitive chemotherapeutic alkylating agent is provided in the form of a solid.

50. The kit according to any of claims 45 to 49, wherein the kit further comprises a spatula for use in applying the polymer paste.