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Definitions

• the present invention relates to methods of treatment neurological disorders and to a pharmaceutical composition for the treatment of chronic pain.
• antisense Methods of inhibiting the expression of genes through short single-stranded oligonucleotides or oligoribonucleotides or modified oligonucleotides perfectly complementary to the target mRNA are known as "antisense”.
• ASOs antisense oligonucleotides
• Antisense oligonucleotides are also being evaluated as medicaments for a wide variety of diseases.
• RNA interference is a process of sequence-specific, post-transcriptional gene silencing initiated by double-stranded RNA that is homologous in sequence to the silenced gene.
• RNAi RNA interference
• RNA interference The modulation of the function of a target nucleic acid by oligoribonucleotides which inhibit the expression of said target nucleic acid is generally referred to as "RNAi" or "RNA interference".
• Effective target-gene specific inhibition is usually achieved by short double-stranded (ds) oligoribonucleotide and with an overhang of approximately 2 nucleotides at the ends of at least 1 strand of the duplex.
• double-stranded oligoribonucleotides are known as short interfering RNAs (siRNAs) and have for instance been used as a tools to help elucidate gene function.
• oligonucleotides inhibiting the expression of specific target gene for therapeutic uses.
• One of the problems encountered is that, due to the special characteristics of oligonucleotides (such as for example high molecular weight, high amounts of negative charge, metabolic instability), delivery of free oligonucleotides to target tissues is generally much more limited in terms of the variety of disease target tissues, than for small molecule inhibitors: for instance, free oligonucleotides have low bioavailability when given orally to patients, systemic delivery of oligonucleotides leads to high levels of drug concentrated in a small number of organs, for example in liver, spleen and kidney, where the distribution is dependent on the format of the oligonucleotide (Feng et al., in 2000, European Journal of Pharmaceutical Sciences 10, 179-186).
• oligonucleotides Delivery of oligonucleotides to the Central Nervous System (CNS) poses particular problems due to the blood brain barrier (BBB) that free oligonucleotides cannot cross.
• BBB blood brain barrier
• One means to deliver oligonucleotides into the CNS is intrathecal delivery.
• the oligonucleotides need also to be efficiently internalised into target cells of the CNS in order to achieve the desired therapeutic effect.
• delivery reagents such as liposomes, cationic lipids, nanoparticles forming complexes are utilized in order to aid the intracellular intemalization of oligonucleotides into cells of neuronal origin.
• the present invention relates to a method to treat or ameliorate neurological disorders comprising intrathecal injection of an effective amount of a double stranded (ds) RNA into a subject in need, wherein said dsRNA inhibits the expression of a target gene.
• the neurological disorder is selected from the group consisting of Alzheimer, Parkinson, multiple sclerosis, schizophrenia, epilepsy, depression and pain.
• the disorder is chronic pain, preferably chronic neuropathic pain, cancer pain or osteoarthritis pain.
• the disorder is allodynia or hyperalgesia.
• the disorder is inflammatory chronic pain.
• the target gene is selected from the group consisting of purine receptors P1 or P2, Galanin R1 receptor, Vanilloid receptors 1, voltage gated calcium channel (N-type), the tetrodotoxin-resistant sodium channel Nav1.8 (PN3/SNS), TRPM8, IL- 24, IL-20Ralpha or IL-20Rbeta.
• P2 receptors most preferred is P 2 X 3 or P 2 X 2 -
• Further preferred target genes include Mob-5 or MMP7.
• the subject in need is preferably mammalian.
• the subject in need is rodent, preferably a rat.
• the subject in need is a monkey or a human.
• the amount of dsRNA that is intrathecally injected is 50 ⁇ g to 1500 ⁇ g, preferably more than 180 ⁇ g, more preferably more than 200 ⁇ g, more than 300 ⁇ g or more than 400 ⁇ g.
• the dsRNA comprises a double-stranded region of 15 to 25 nt, preferably of 19 nt.
• the dsRNA comprises a 3' overhang on the antisense or the sense strand or both strands of at least one nucleotide, preferably 1 , 2, 3 or 4 nucleotides.
• the penultimate nucleotide of the overhang is complementary to the mRNA target strand.
• the overhang contains at least one modified nucleotide, a preferred modification is a 2-MOE modification.
• the overhang comprises at least one UU and / or dTdT group. Also preferred is an overhang comprising UUUU or consisting of UUUU.
• the dsRNA comprises at least one modified linkage, preferred is at least one phosphorothioate linkage.
• dsRNA for the treatment of chronic pain.
• the dsRNA is preferably administered by intrathecal injection to a subject in need and inhibits the expression of a target gene.
• the chronic pain is chronic neuropathic pain
• the chronic pain is selected from the group consisting of cancer pain, osteoarthritis pain, allodynia or hyperalgesia.
• the targeted gene is a gene encoding a purine receptors P1 or P2, Galanin R1 receptor, Vanilloid receptors 1 , voltage gated calcium channel (N-type), the tetrodotoxin-resistant sodium channel Nav1.8 (PN3/SNS), TRPM8, IL- 24, IL-20Ralpha or IL-20Rbeta, most preferred is a gene encoding P 2 X3 or P 2 X 2 .
• Further preferred genes include Mob-5 or MMP7.
• Another aspect of the present invention relates to pharmaceutical compositions comprising an effective amount of dsRNA, wherein the dsRNA inhibits the expression of a target gene.
• These target genes are preferably overexpressed in chronic pain, preferably chronic neuropathic pain.
• Preferred target genes are the purine receptors P1 or P2, Galanin R1 receptor, Vanilloid receptors 1 , voltage gated calcium channel (N-type), the tetrodotoxin- resistant sodium channel Nav1.8 (PN3/SNS), TRPM8, IL-24, IL-20Ralpha or IL-20Rbeta. Particularly preferred are the P2 receptors, most preferred is P 2 X 3 or P 2 X 2 . Further preferred target genes include Mob-5 or MMP7.
• the pharmaceutical composition comprising an effective amount of a double stranded RNA is selected from the group consisting of SEQ ID Nos: 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 and 16.
• double-stranded ribonucleic acid refers to an oligoribonucleotide or polyribonucleotide, modified or unmodified, and fragments or portions thereof, of genomic or synthetic origin or derived from the expression of a vector, which may be partly or fully double-stranded and which may be blunt-ended or contain a 5'- and/or 3'-overhang, and also may be of a hairpin form comprising a single oligoribonucleotide which folds back upon itself to give a double-stranded region.
• dsRNA double-stranded ribonucleic acid
• RNA denotes short interfering RNAs and refers to short double stranded ribonucleic acids useful for RNAi.
• inhibition of gene expression means the reduction of the expression of said gene by at least 10%, 33%, 50%, 90%, 95% or 99%.
• the term "form" of or “format” of in relation to oligonucleotides refers to different chemical nature of the oligoribonucleotide, in particular to modifications as compared to naturally occurring ribonucleotides, such as for instance chemically modified 2'OH groups of the ribose moiety or the modified intemucleosidic linkages such as phosphothioate linkages, or the modified nucleobases such as for example 5-methyl-C.
• Subject refers to any human or nonhuman organism. Preferred are mammalian organisms.
• nucleotide means ribonucleotide or deoxyribonucleotide
• oligonucleotide and oligoribonucleotide are interchangeable and refer, depending on the context, to modified or unmodified oligonucleotides comprising ribonucleotides and / or deoxyribonucleotides.
• the present invention is based on the surprising discovery that intrathecally injected dsRNA inhibited the expression of a target gene thereby leading to a therapeutic effect in vivo, thus providing for the first time that a successful therapeutic treatment of a neurological disorder has been achieved by administration of dsRNA.
• the magnitude of the pharmacological effect from the siRNA on allodynia is much greater than that from the analogous antisense oligonucleotide.
• a dose limiting toxicity from use of the antisense oligonucleotide does not allow a pharmacological effect on allodynia to be observed, whereas no such does limiting toxicity was observed from use of the siRNA, showing the possible advantages of using siRNAs over ASOs.
• the present invention makes therefore dsRNA available for the therapeutic treatment of neurological diseases.
• the ribonucleic acid used for inhibition will have at least a partially double-stranded character, but may also be totally double-stranded.
• the RNA can be a single strand that is self-complementary or may comprise two or more separate complementary strands.
• RNAs also termed siRNAs, having a length of 10 to 50 nucleotides, preferably 15 to 25 nucleotides.
• dsRNA's composed of oligoribonucleotides having a duplex length of 17 to 21 ribonucleotides.
• the efficiency i.e. the degree of inhibition of the target gene, is dependent on a number of different factors including the specificity of the dsRNA for its target sequence. In this context, specificity means homology, i.e.
• sequence identity between the dsRNA in the duplex region and the target sequence it is understood by a person skilled in the art that 100% sequence identity is not required in order to achieve significant inhibition. Normally, at least 75% sequence identity between the dsRNA and the target sequence is sufficient in order to inhibit expression of the target nucleic acid. Preferred is a sequence identity of at least 80%, more preferred is a sequence identity of at least 90%. Most preferred is a sequence identity of at least 95% between the dsRNA and the target sequence. The best is clearly 100%. In order to target only the desired target mRNA, the siRNA reagent should have 100% homology to the target mRNA and at least 2 mismatched nucleotides to all other genes present in the cell or organism.
• Sequence identity may be optimized by sequence comparison and alignment algorithms known in the art (see Gribskov and Devereux, Sequence Analysis Primer, Stockton Press, 1991 , and references cited therein) and calculating the percent difference between the nucleotide sequences by, for example, the Smith-Waterman algorithm as implemented in the BESTFIT software program using default parameters (e.g., University of Wisconsin Genetic Computing Group).
• Another factor affecting the efficiency of the RNAi reagent is the target region of the target mRNA. The region of a target mRNA effective for inhibition by the RNAi reagent may be determined by experimentation.
• mRNA target region would be the coding region.
• untranslated regions particularly the 3'-UTR, splice junctions.
• transf ection assays as described in Elbashir et al. (2001) may be performed for this purpose.
• a number of other suitable assays and methods exist in the art which are well known to a person skilled in the art.
• the dsRNA according to the present invention may also contain modified nucleotide residues.
• siRNAs can exist in various formats as described in Tolen et al.2002, Nucl. Acids Res. 30, 1757-1766; Elbashir S.M. et al, 2001 EMBO J., 20, 6877-6888; FEBS 2002, 521, 195-199; Current Biology 2001 , 11 , 1776-1780; Nature Biotech. 2002, 19, 497-500; Nature Biotech.
• the dsRNA may be blunt ended or ligated at or on at least one end with either loops composed of ribonucleotides or deoxyribonucleotides or a chemical synthetic linker (WO00/44895).
• the ribonucleic acid contains 3'-end nucleotide overhangs on the antisense strand and / or the sense strands of the dsRNA of at least one ribonucleotide or deoxyribonucleotide, or modified nucleotide.
• overhangs with 1 , 2, 3 or 4 nucleotides.
• the overhangs may contain both ribonucleotide(s) and deoxyribonucleotide(s) which in addition may contain modified sugar moieties.
• the overhang may be of any sequence, but in a preferred embodiment, the overhang is complementary to the target mRNA strand.
• the overhang contains at least one UU group or dTdT group.
• the overhang on the antisense strand has the penultimate overhanging nucleotide complementary to the mRNA target strand.
• such an overhang is a 2-nucleotides overhang.
• the overhang is composed of 4 Us.
• the extreme 3'-position of the siRNA is a hydroxyl group.
• the 5'-end may be a hydroxyl or phosphate group.
• the sugar moieties may be unmodified or modified.
• Preferred modified sugar moieties oligonucleotides comprise one of the following at the 2' position: F; O-, S-, or N- alkyl; O-, S-, or N-alkenyl; O-, S- or N-alkynyl; or O-alkyl-O-alkyl, wherein the alkyl, alkenyl and alkynyl may be substituted or unsubstituted C 1 to C 10 alkyl or C2 to C10 alkenyl and alkynyl.
• oligonucleotides comprise one of the following at the 2' position: C1 to C10 lower alkyl, substituted lower alkyl, alkaryl, aralkyl, O-alkaryl or O-aralkyl, SH, SCH3, CI, Br, CN, CF3, OCF3, SOCH3, SO2 CH3, ONO2, NO2, N3, NH2, heterocycloalkyl, heterocycloalkaryl, aminoalkylamino, polyalkylamino, substituted silyl, an RNA cleaving group, a reporter group, an intercalator, a group for improving the pharmacokinetic properties of an oligonucleotide, or a group for improving the pharmacodynamic properties of an oligonucleotide, and other substituents having similar properties.
• a preferred modification includes 2'-methoxyethoxy (2'-O ⁇ CH2 CH2 OCH3, also known as 2'-O ⁇ (2-methoxyethyl) or 2'-MOE) (Martin et al., Helv. Chim. Acta, 1995, 78, 486- 504) i.e., an alkoxyalkoxy group.
• a further preferred modification includes 2'- dimethylaminooxyethoxy, i.e., a O(CH2)2 ON(CH3)2 group, also known as 2'-DMAOE, 2'- methoxy (2'-O-CH3), 2'-aminopropoxy (2'-OCH2 CH2 CH2 NH2).
• a further preferred modification of this category is the bicyclic class of modifications known collectively as LNAs (Locked Nucleic Acids) as described in Rajwanshi et al., Angew. Chem. Int. Ed. 2000, 39, 1656-1659.
• LNAs Locked Nucleic Acids
• One of skill in the art may use conventional methods to created such modified sugar structures.
• Representative United States patents that teach the preparation of such modified sugar structures include, but are not limited to, U.S. Pat. Nos. 4,981 ,957; 5,118,800; 5,700,920 and 5,969,116 each of which is incorporated by reference herein in its entirety.
• the internucleoside linkage of the dsRNA may be the "normal" 3' to 5' phosphodiester linkage or contain at least one chemically modified linkage.
• the at least one overhanging nucleotides contains one or more modified linkages, whereas the double-stranded part of the oligonucleotide contains phosphodiester internucleoside linkages.
• Preferred modified linkages include but are not limited to, for example, those disclosed in U.S. Pat. Nos. 3,687,808; 4,469,863 and 5,625050; each of which is incorporated by reference herein in its entirety.
• linkages are phosphorothioates, chiral phosphorothioates or phosphorodithioates.
• the oligoribonucleotides may be prepared by chemical synthesis (Micura R., Angewandte Chemie, International Edition (2002), 41(13), 2265-2268) on commercially available or homemade oligonucleotide synthesizers using a number of different chemistries that are well known in the art.
• the oligonucleotide may also be prepared by in vitro transcription of a suitable template using for instance a commercially available kit such as the SilencerTM siRNA construction kit by Ambion.
• the oligoribonucleotides may be synthesized by transcription of siRNA's intracellularly from plasmids through both transient or stable transfection (Paddison PJ et al., 2002, Genes and Development 16, 948- 958, Paul et al., 2002, Nat. Biotech 29, 505-508).
• dsRNA The effect of dsRNA on gene expression will typically result in expression of the target gene being inhibited by at least 10%, 33%, 50%, 90%, 95% or 99% when compared to a cell not treated according to the present invention.
• Lower doses of administered material, lower concentrations of dsRNA in the cell and/or longer times after administration of dsRNA may result in inhibition at a lower level and/or in a smaller fraction of cells (e.g., at least 10%, 20%, 50%, 75%, 90%, or 95% of targeted cells).
• Quantitation of gene expression can be established by assessing the amount of the targeted gene product in the cell. For example, any mRNA transcribed from the target gene may be detected with a hybridization probe, or RT-PCR based methodologies, or translated polypeptide may be detected with an antibody raised against the encoded polypeptide.
• the dsRNA is delivered in accordance with the present application by intrathecal injection (i.e. injection into the spinal fluid which bathes the brain and spinal chord tissue).
• intrathecal injection i.e. injection into the spinal fluid which bathes the brain and spinal chord tissue.
• Intrathecal injection of siRNA's into the spinal fluid can be performed as a bolus injection or via minipumps which can be implanted beneath the skin, providing a regular and constant delivery of siRNA into the spinal fluid.
• the amount of intrathecally injected dsRNA may vary from one target gene to another target gene and the appropriate amount that has to be applied may have to be determined individually for each target gene. Typically this amount will be in the range between 10 ⁇ g to 2mg, preferably 50 ⁇ g to 1500 ⁇ g, more preferably 100 ⁇ g to 1000 ⁇ g. It has been found in accordance with the present invention that the dose limiting toxicity was at much lower amount of oligoribonucleotides for ASOs than for siRNA. For instance, whereas a dose limiting toxicity in the rat model was observed at 180 ⁇ g per day for ASOs, such a dose limiting toxicity was still absent at 400 ⁇ g per day for siRNAs.
• the dose of the intrathecally injected siRNA is at least 50 ⁇ g, more preferably at least 100 ⁇ g, more preferably at least 150 ⁇ g per day, more preferably at least 180 ⁇ g, more preferably at least 200 ⁇ g, more preferably at least 300 ⁇ g, most preferably at least 400 ⁇ g. It will be apparent to a person of skill in the art that the dose of intrathecally injected dsRNA will have to be adjusted appropriately in other organisms, the appropriate dose for humans, for instance, may be considerably higher.
• the gene to be inhibited is expressed in the CNS.
• the target gene is often, but not always a gene which is misregulated, often upregulated in a given disease state.
• genes expressed in the CNS are genes for cytokines, genes causal for neuro-degeneration or regeneration such as Alzheimer or Parkinson or multiple sclerosis, viral genes from viruses infecting the CNS, genes causal for schizophrenia, epilepsy or depression. In a preferred embodiment the gene is causal for pain.
• Pain is a term that encompasses a spectrum of clinical states. Acute pain serves as a physiological warning for a potentially tissue-damaging situation. Chronic pain occurs when the stimulus and pain are unrelated and the pain is no longer a protective mechanism. Chronic pain states are characterised by a number of clinical features. As well as spontaneous pain, patients may exhibit hyperalgesia (a greatly exaggerated response to a noxious mechanical, temperature or chemical), and allodynia (previously non-noxious stimuli are now perceived as painful). All these features result from a complex series of events involving changes in the function of sensory nerves in the periphery and in the processing of sensory information in the spinal cord and brain. These changes occur in response to direct neuronal damage or in response to mediators released during tissue damage or inflammation.
• chronic pain syndromes can be defined as inflammatory (also known as nociceptive) or neuropathic.
• Chronic inflammatory pain occurs during conditions in which there is underlying inflammation such as rheumatoid arthritis, burns, muscle damage or surgical wounds.
• Knowledge of the mechanisms underlying inflammatory pain has advanced considerably over recent years and it is known to involve a variety of mediators and their activation and sensitization of the peripheral terminals of sensory nerves and the consequent longer term changes in reactivity of spinal cord neurons.
• Chronic neuropathic pain is caused where there is a primary lesion or dysfunction of the nervous system and occurs, for example, during conditions such as trigeminal neuralgia, diabetic neuropathy, post-herpetic neuralgia, amputation or physical nerve damage.
• Chronic neuropathic pain results from damage to nerves by trauma, by diseases such as diabetes, herpes zoster, or late-stage cancer (see below), or by chemical injury (e.g. some anti-HIV drugs). It may also develop after amputation (including mastectomy), and is involved in some low-back pain.
• chronic neuropathic pain The mechanisms of chronic neuropathic pain are poorly understood but are thought to involve spontaneous firing of sensory nerves due to the novel expression of certain classes of ion channel, sprouting of sensory fibres into different layers of the spinal cord, and changes in the expression of various neurotransmitters and receptors in the sensory nerves and spinal cord.
• chronic neuropathic pain has proven to be intractable and is resistant to the standard non- steroidal and opiate analgesics. There is therefore clearly an unmet clinical need for new analgesics to treat this type of pain.
• Cancer pain is the most common chronic pain syndrome (with probably inflammatory and neuropathic components). It is estimated that one third of patients with advanced cancer will develop skeletal metastases, particularly in breast, prostate and lung cancer.
• Metastatic bone disease commonly results in bone pain that is usually located to a discrete area and is described as a deep, boring sensation that aches and burns, accompanied by episodes of stabbing discomfort.
• the mechanisms responsible for bone cancer pain are unknown but it probably involves structural damage, periosteal irritation and nerve entrapment.
• Current treatment of bone cancer pain rests with opiates but the doses required results in unacceptable side-effects and at least 20 % of patients still have uncontrolled pain. Novel, well tolerated and effective analgesics are desired to optimise the quality of life of these patients (Coleman RE (1997) Cancer 80; 1588-1594).
• Osteoarthritis pain is the most common form of chronic neuropathic pain (with probably inflammatory and neuropathic components) for which people visit general practitioners. Osteoarthritis is a chronic disease involving progressive structural changes in joint tissues, principally cartilage, synovium and subchondral bone. Typically, arthritic joints exhibit cartilage oedema and erosion, subchondral bone and synovial thickening, and formation of bony oesteophytes, all contributing to a deformation of the articular surface. The principal clinical symptom of osteoarthritis is pain, although the mechanisms underlying the chronic neuropathic pain in this condition are not understood.
• the gene is causal for chronic pain.
• Genes causal for pain can be determined using for instance the animal models described hereinbelow.
• the gene encodes a member of the family of the purine receptors Pi or P 2 (Ralevic & Burnstock, Pharmacological Reviews 50 (1998), 413-492), preferably a member of the P Y or P 2 X subclass. More preferred are the P 2 X 3 or the P 2 X 2 gene.
• genes include, but are not limited to Cathepsin S (NM_004079), TrpM8 (NM_024080), the Galanin R1 receptor (Jacoby AS et al., Genomics (1997) 45:3496-508, NM_012958, NM_008082, NM_001480) or the genes described in US Patent Application 60/369893 such as for instance IL-24 (NM_006850), IL- 20Ralpha or IL-20Rbeta (NM_014432 and AAZ20504).
• the gene encodes a member of the Mob-5 familiy.
• Mob-5" refers to Mob-5, Genbank # AAF75553 as well as the human ortholog of this protein, Interleukin 24 (Genbank # AAA91780).
• the human ortholog of rat Mob-5 is also known as hMDA-7 as well as "suppression of tumorigenicity 16 (Jiang.H et al., Oncogene 11, 2477-2486,1995).
• genes include any and all forms of these polypeptides including, but not limited to, variants, partial forms, isoforms, precursor forms, full length polypeptides, fusion proteins or fragments of any of the above, from human or any other species.
• Apparent variants of Mob-5 include for instance c49a Genbank, Accession Number NM; AAB69171. Homologs of the above genes, which would be apparent to one of skill in the art, are also meant to be included in this definition.
• the term refers to the above genes isolated from naturally occurring sources of any species such as genomic DNA libraries as well as genetically engineered host cells comprising expression systems, or produced by chemical synthesis using, for instance, automated peptide synthesizers or a combination of such methods. Means for isolating and preparing such polypeptides are well understood in the art.
• the gene encodes MMP7 (matrilysin), a matrix metalloproteinase.
• MMP7 refers to any and all forms of this polypeptide including, but not limited to, variants, partial forms, isoforms, precursor forms, the full length polypeptide, fusion proteins containing the MMP7 sequence or fragments of any of the above, from human or any other species.
• the sequence of rat MMP7 may be found in Genbank, Accession Number NM_012864. Homologs and orthologs of MMP7, which would be apparent to one of skill in the art, are meant to be included in this definition.
• MMP7 isolated from naturally occurring sources of any species such as genomic DNA libraries as well as genetically engineered host cells comprising expression systems, or produced by chemical synthesis using, for instance, automated peptide synthesizers or a combination of such methods. Means for isolating and preparing such polypeptides are well understood in the art.
• the gene that is targeted is of mammalian origin, in a more preferred embodiment the gene is a rodent gene, most preferred is a rat gene. In another preferred embodiment the gene is a monkey or a human gene.
• Another aspect of the present invention provides a pharmaceutical composition comprising an effective amount of a double stranded RNA inhibiting the expression of a gene causal for pain in an amount effective to treat chronic pain in a subject in need.
• the gene is regulated in chronic neuropathic pain models).
• the genes encode for a Pi or P Purine Receptor, more preferably for a receptor of the P Y or P 2 X subclass. Most preferred are the P 2 X 3 or the P 2 X 2 gene.
• Vanilloid receptors 1 voltage gated calcium channel (N-type), the tetrodotoxin-resistant sodium channel Nav1.8 (PN3/SNS), TRPM8, the Galanin R1 receptor or the genes described in US Patent Application 60/369893 such as for instance IL-24, IL-20Ralpha or IL-20Rbeta.
• compositions disclosed herein useful for treating and/or ameliorating chronic pain are to be administered to a patient at therapeutically effective doses to treat or ameliorate symptoms of such disorders.
• a therapeutically effective dose refers to that amount of the compound sufficient to result in amelioration of pain symptoms of chronic pain based on, for example, use of the McGill pain score (Melzack, R. Pain (1975) Sept. 1 (3):277-299).
• compositions and formulations for intrathecal administration may include sterile aqueous solutions which may also contain buffers, diluents and other suitable additives such as, but not limited to, penetration enhancers, carrier compounds and other pharmaceutically acceptable carriers or excipients.
• compositions of the present invention include, but are not limited to, solutions, emulsions, and liposome-containing formulations.
• the pharmaceutical formulations of the present invention may be prepared according to conventional techniques well known in the pharmaceutical industry. Such techniques include the step of bringing into association the active ingredients with the pharmaceutical carrier(s) or excipient(s). In general the formulations are prepared by uniformly and intimately bringing into association the active ingredients with carriers.
• compositions of the present invention may be formulated into any of many appropriate dosage forms.
• the compositions of the present invention may for instance be formulated as suspensions in aqueous or mixed media.
• Aqueous suspensions may further contain substances which increase the viscosity of the suspension including, for example, sodium carboxymethylcellulose, sorbitol and/or dextran.
• the suspension may also contain stabilizers.
• compositions suitable for use in the invention include compositions wherein the active ingredients are contained in an effective amount to achieve the intended purpose.
• the determination of an effective dose is well within the capability of those skilled in the art.
• a therapeutically effective dose refers to that amount of active ingredient, i.e. double-stranded RNA in accordance with the present invention, useful to treat and/or ameliorate the pathological effects of chronic pain.
• Therapeutic efficacy and toxicity may be determined by standard pharmaceutical procedures in cell cultures or experimental animals, e.g., ED50 (the dose therapeutically effective in 50% of the population) and LD50 (the dose lethal to 50% of the population). The dose ratio between toxic and therapeutic effects is the therapeutic index, and it can be expressed as the ratio, LD50/ED50.
• Pharmaceutical compositions that exhibit large therapeutic indices are preferred. The data obtained from cell culture assays and animal studies is used in formulating a range of dosage for human use. The dosage contained in such compositions is preferably within a range of circulating concentrations that include the ED50 with little or no toxicity. The dosage varies within this range depending upon the dosage form employed, sensitivity of the patient, and the route of administration.
• the exact dosage will be determined by the practitioner, in light of factors related to the subject that requires treatment. Dosage and administration are adjusted to provide sufficient levels of the active moiety or to maintain the desired effect. Factors that may be taken into account include the severity of the disease state, general health of the subject, age, weight, and gender of the subject, diet, time and frequency of administration, drug combination(s), reaction sensitivities, and tolerance/response to therapy. Guidance as to particular dosages and methods of delivery is provided in the literature and generally available to practitioners in the art.
• Another aspect of the present invention provides the use of a double stranded RNA for the preparation of a medicament for the treatment of chronic pain.
• the double stranded RNA inhibits purine receptors P1 or P2 or Galanin R1 receptor or IL-24 or IL- 20Ralpha or IL-20Rbeta or MMP7, more preferably Mob-5 or P2X3 or P2X2.
• Said chronic pain is preferably cancer pain or osteoarthritis pain, more preferably hyperalgesia, most preferably allodynia.
• ASOs Antisense oligonucleotides
• the ASOs against P 2 X 3 and GAPDH are fully phosphorothioated 18-mers with nine nucleotides at the 3'-end modified with 2'-MOE groups and were synthesized using phosphoramidite chemistry (Eur. Pat. Appl. EP 992506 A2), HPLC-purified and characterized by electrospray mass spectrometry and capillary gel electrophoresis.
• the approximate base composition of the match oligonucleotides was maintained (Table 1 ).
• intemucleotidic linkages are phosphodiester
• N deoxyribonucleoside
• n 2'-O-(2-methoxyethyl) ribonucleoside
• c 2'-O-(2-methoxyethyl) 5- methyl cytidine
• t 2'-O-(2-methoxyethyl) 5-methyl uridine
• s phosphorothioate.
• Oligoribonucleotides siRNA's
• Modified synthetic oligoribonucleotides and modified antisense oligonucleotides described in this invention are prepared using standard phosphoramidite chemistry on ABI394 or Expedite/Moss Synthesizers (Applied Biosystems) for in vitro use and on OligoPilot II (Amersham Pharmacia Biotech) for in vivo purpose.
• Phosphoramidites are dissolved in acetonitrile at 0.05 M concentration (0.2M on Oligopilot II), coupling is made by activation of phosphoramidites by a 0.2 M solution of benzimidazolium triflate in acetonitrile. Coupling times are usually comprised between 3-6 minutes.
• a first capping is made using standard capping reagents. Sulfurization is made by using a 0.05 M solution of N-ethyl, N- phenyl-5-amino-1 ,2,4-dithiazol-3-thione for two minutes (described in EP-A-0992506). Oxidation is made by a 0.1 M iodine solution in THF/PyridineA/Vater (1 :1 :1) for two minutes. A second capping is performed after oxidation or sulfurization. Oligonucleotide growing chains are detritylated for the next coupling by 2% dichloroacetic acid in dichloromethane or dichloroethane.
• the support-bound compounds are cleaved and deprotected as "Trityl-on" by a Methylamine solution (41 % aqueous methylamine/33% ethanolic methylamine 1 :1 v/v) at 35°C for 6 h for oligoribonucleotides and by a 32% aqueous Ammonia solution at 55°C for 16h for antisense oligonucleotides. Resulting suspensions are lyophilised to dryness. For oligoribonucleotides, 2'-O-silyl groups are removed upon treatment with 1 M tetrabutylammonium fluoride 10min at 50°C and 6h at 35°C.
• the obtained crude solutions are directly purified by RP-HPLC.
• the purified detritylated compounds are analysed by Electrospray Mass spectrometry and Capillary Gel Electrophoresis and quantified by UV according to their extinction coefficient at 260 nM.
• the oligoribonucleotides and antisense oligonucleotides directed against rat P2X3 and MOB-5 and their controls are shown in table 3 and 4, respectively.
• RNAs NAS-8646 and NAS-8647, NAS-7556 and NAS-7557, NAS-4882 and NAS- 4883, NAS-4884 and NAS-4885, NAS-7127 and 7126 as well as NAS-10104 and NAS- 10105 are annealed together to give the siRNA's.
• NAS-8646 and NAS-8647 as well as NAS- 10104 and 10105 have 2'-MOE ribonucleotides at the 3'-terminus of the oligoribonucleotide, and the sequence NAS 8647 is fully complementary to the target gene.
• NAS-7556 and NAS- 7557 have 2'-MOE-A ribonucleotides at the 3'-terminus of the oligoribonucleotides; NAS- 4882 and NAS-4883 have 2-dT deoxyribonucleotides at the 3'-terminus of the oligoribonucleotide; NAS-4884 and NAS-4885 have 2-dT deoxyribonucleotides at the 3'- terminus of the oligoribonucleotide.
• the oligoribonucleotides NAS-7126 and 7127 target an unrelated gene.
• internucleotidic linkages are phosphodiester
• N ribonucleoside
• n 2 -O-(2-methoxyethyl) ribonucleoside
• c 2'-O-(2-methoxyethyl) 5- methyl cytidine
• t 2'-O-(2-methoxyethyl) 5-methyl uridine
• dN deoxyribonucleoside
• s phosphorothioate.
• RNAs NAS-11535 and NAS-11536, NAS-11537 and NAS-11538 are annealed together to give the siRNA's.
• rP 2 X 3/2 -CHO rP2X3 insert was obtained by PCR using as template RT from total rat DRG RNA and using the oligos listed below:
• P2X3-Hind-F CGCAAGCTTGGCTGTGAGCAGTTTCTCAGTATGAACTTG (SEQ ID No 17)
• P2X3- Sacl-R CTTGAGCTCGGGAAGAGGCCCTAGTGACCAATAG (SEQ ID No 18)
• the underlined sequence is a Hindi 11 restriction enzyme site added to the P2X3 complementary oligo.
• the Sacl site in the reverse primer was not used for cloning.
• the PCR product was amplified using Advantage-HF2 Polymerase with thermal cycling at 94°C for 30 s, 62°C for 60 s, and 68°C for 180 s for 6 cycles and 94°C for 30 s, and 68°C for 240 s for additional 29 cycles
• the PCR fragment was cloned in pGEM T-Easy (Promega) and sequenced with T7 and M13 reverse primers.
• the clone had the same sequence as the Genbank cDNA with accession number X91167.
• rP2X3 insert was cut out of pGEM T-Easy by digestion with Notl and subcloned into pcDNA5/FRT linearized with Notl and dephosphorylated.
• rP2X2 was obtained by digestion with BamHI and Xhol of a clone (see above). rP2X2 was subcloned into pcDNA5/FRT-Neo cut with the same enzymes.
• the cell line used was RBA (ATCC number 1747). It is rat skin derived, grows extremely tightly attached in a flattened out, skin-like morphology, and naturally expresses ras and mob-5 (known to be ras-downstream).
• Oligo concentration Average fg/50 ng total RNA 7428, 400nM 5.03E+02 7428, 200nM 5.47E+02 7428, 100nM 7.13E+02
• CHO-rP2X2/3 cells were transfected with 0.15; 0.3; 0.6 or 1.2 nmole of ASO or siRNA duplex using standard electrotransfection (10 6 cells/125 ul in Biorad cuvette 0.4 cm, 250V, 0.3 ⁇ , infinite resistance). Following electroporation, samples were immediately combined with 6 ml of the culture medium. In result, corresponding final concentration of ASO or siRNA reagents were 10, 50, 100 or 200 nM. Cells were plated on uncoated 96-well plates (Costar, Cat. #3904) and incubated at 37°C for 24h or 48h, followed by RNA or protein extraction, respectively.
• Reverse transcription and real time PCR was performed in a GeneAmp Sequence Detector 5700 (PE Biosystems) as follows: 2 minutes reverse transcription at 50°C, 10 minutes denaturation at 95°C followed by 50 cycles of denaturation for 15 sec at 95°C and annealing and elongation for 1 min at 60°C.
• the relative quantitation of gene expression was calculated as described in the ABI PRISM 7700 user bulletin #2 (PE Biosystems).
• the filters were blocked for 1 h with the blocking buffer contained in the ECF Western Blotting Kit (Amersham Pharmacia Biotech), washed several times in 1x PBS, pH 7.4 with 0.05% Tween 20, and incubated for 1h with the primary anti-P2X3-antibody (purchased from Neuromics) in a dilution 1:5000. With several washes in between, the filters were then incubated with the secondary antibody, tertiary antibody and ECF substrate from the ECF Western Blotting Kit following the manufacturer's suggestions. A quantification of the visualized bands was done with the software ImageQuantTM (Molecular Dynamics).
• FLIPR experiments were performed as follows. Briefly, cells were loaded with fluo-4 AM in presence of 2.5 mM probenicid for 30-45 min, washed twice with HBSS (Gibco) + 20mM HEPES, and transferred to the fluorescence reader (FLIPR, Molecular Devices). Drug plates were prepared at 5x the final concentration. Fluo-4 fluorescence was measured at a rate of 0.5 Hz for 3 min. Agonists were applied after 20 points baseline detection.
• FLIPR sequence files were analyzed using Igor Pro (Wavemetrics). Baseline was set as the average of 20 points before drug addition, peak was detected as maximal signal in the 50 data points after drug addition. Relative change of fluorescence (dF/F) was determined as (peak - baseline) / (baseline) values. These values were averaged, and for concentration-response analysis further analyzed by fitting a sigmoidal hill equation to the data. Data are presented as mean +/- S.E.M. or EC50 values as mean (95% confidence interval).
• In vivo animal models of chronic neuropathic pain include the following:
• CCI Chronic Constriction Injury
• the Chung model involves ligation of the spinal nerve.
• rats are anesthetized and placed into a prone position and an incision is made to the left of the spine at the L4-S2 level.
• a deep dissection through the paraspinal muscles and separation of the muscles from the spinal processes at the L4-S2 level will reveal part of the sciatic nerve as it branches to form the L4, L5 and L6 spinal nerves.
• the L6 transverse process is carefully removed with a small rongeur enabling visualisation of these spinal nerves.
• the L5 spinal nerve is isolated and tightly ligated with 7- 0 silk suture.
• the wound is closed with a single muscle suture (6-0 silk) and one or two skin closure clips and dusted with antibiotic powder.
• the L5 nerve is exposed as before but not ligated and the wound closed as before.
• the Axotomy model involves complete cut and ligation of the sciatic nerve.
• the nerve endings form neuromas but there is no behavioral correlate in this model as the nerve is not allowed to regenerate, and the foot is permanently denervated. (Kingery and Vallin, Pain 38, 321-32, 1989)
• the Complete Freund's Adjuvant -induced mechanical hyperalgesia may be used as a model of chronic inflammatory pain (Stein, C. et al. Pharmacol. Biochem. Behav. (1988) 31 :445-451).
• a male Sprague-Dawley or Wistar rat 200-250 g receives an intraplantar injection of 25 ⁇ complete Freund's adjuvant into one hind paw. A marked inflammation occurs in this hind paw.
• Drugs are generally administered for evaluation of efficacy, 24 hours after the inflammatory insult, when mechanical hyperalgesia is considered fully established.
• Wistar rats male are employed in the chronic neuropathic pain models described above. Rats weigh approximately 120-140 grams at the time of surgery. All surgery is performed under enflurane/O 2 inhalation anaesthesia.
• Oligonucleotide reagents used in the animal models have been named as the following: ASO: NAS-6798 (SEQ. ID 5), MSO: NAS-6799 (SEQ. ID 6), P2X3 RNAi: NAS-8646 and NAS-8647 (SEQ. ID 7 and 8 respectively), P2X3 RNAi missense: NAS-10104 and NAS- 10105 (SEQ. ID 19 and 20 respectively).
• dsRNA Intrathecal delivery of siRNA.
• Rats were anaesthetised and an incision made in the dorsal skin just lateral to the midline and approximately 10 mm caudal to the ventral iliac spines.
• a sterile catheter polyethylene PE10 tubing
• the catheter was then connected to an osmotic mini-pump (Alzet) delivering P2X3 receptor or MOB-5 receptor siRNA, missense siRNA or saline (1 ⁇ I h, 7 days) which was inserted subcutaneously in the left or right flank. The incision was closed with wound clips and dusted with antibiotic powder. Experiments determined 180 as well as 220 ⁇ g/day to have no signs of toxicity. Mechanical hyperalgesia was assessed on day 0, day 6 before administration of ⁇ , ⁇ -methylene-ATP (Me-ATP) and 1 h post Me-ATP by measuring paw withdrawal thresholds of both hindpaws to an increasing pressure stimulus using an Analgesymeter (Ugo-Basile, Milan).
• Me-ATP ⁇ , ⁇ -methylene-ATP
• Analgesymeter Ugo-Basile, Milan.
• the cut-off was set at 250 g and the end-point taken as paw withdrawal, vocalisation or overt struggling. Each animal was tested only once, in random order. The statistical significance of mechanical hyperalgesia data obtained from the different experimental animal groups was analysed using ANOVA followed by Tukey's HSD test. I.O ⁇ mol (in 10 ⁇ l) of Me-ATP was given intraplantar (ipl) to the contralateral hindpaw on the final day of the experiment. 1.0 h post administration, paw withdrawal thresholds to mechanical hyperalgesia were measured.
• FLIPR functional assay Downregulation of functional response to 10 ⁇ M Me-ATP agonist by transfection of ASO-NAS-5037 and siRNA NAS-8646/8647 into a CHO-r P2X2/P2X3 cell line at concentrations of 10, 50, 100, and 200 nM 48h prior to agonist treatment as compared to untreated control and to mismatch controls (MSO-5655and siRNA NAS-7557/7558).
• Rats were ligated on the left hind limb on day 0 and base line mechanical hyperalgesia was measured daily. An additional unligated group (na ⁇ ve) was set up as control. Rats were cannulated on day 11 and infused with vehicle, RNAi, RNAi missense or ASO for a further 6 days. Paw withdrawal thresholds (left paw) were measured daily. Vehicle: isotonic buffer, n 8/treatment group.

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