Field of the invention [0001 ] The present invention relates to the treatment of retinal neurodegenerative disorders, and more particularly to the treatment by maintaining the integrity of the cone photoreceptors and by reactivating cones which have already lost their outer segment.

Background Art

[0002] Neurodegenerative disorder encompasses a range of seriously debilitating conditions that are characterized by neuron degeneration.

[0003] Photoreceptors, such as rods and cones, are light-sensitive sensory neurons found on the posterior layer of the retina. They are also called photoreceptor cells or photoreceptor neurons.

[0004] Retinal neurodegenerative disorders or retinal degenerative diseases encompass different subgroups of pathologies: Rod-cone dystrophies, Cone dystrophies, Cone-rod dystrophies, and atrophic age-related macular degeneration.

[0005] Rod-cone dystrophies (RCD), such as retinitis pigmentosa (RP), are genetically heterogeneous retinal neurodegenerative diseases characterized by the progressive death of rod photoreceptors followed by the consecutive loss of cones. RP is one of the most common forms of inherited retinal degeneration, affecting around 1 :3,500 people worldwide (1), which represents 2 million patients worldwide. Mutations causing RP in over 63 distinct genes have been identified to date with a significant proportion of these mutations in rod- specific transcripts.

[0006] Cones dystrophies are characterized by the vision loss (age of onset ranging from the late teens to the sixties), sensitivity to bright lights, and poor color vision. Therefore, patients see better at dusk. Visual acuity usually deteriorates gradually, but it can deteriorate rapidly to 20/200. Later, in more severe cases, it drops to "counting fingers" vision. Color vision testing using color test plates (HRR series) reveals many errors on both red-green and blue-yellow plates.

[0007] Cone-Rod Dystrophies (CRD) refer to a group of inherited retinal degenerations (1 :30 — 40,000 people) that affect the photoreceptor (light sensing) cells that are responsible for capturing images from the visual field. These cells line the back of the eye in the region known as the retina. Cone photoreceptor cells are present throughout the retina, but are concentrated in the central region (the macula). They are useful for central (reading) vision. Rod photoreceptor cells are present throughout the retina except for the very center of the macula called the fovea where only cones are present. They are responsible for night vision. [0008] In contrast to typical retinitis pigmentosa (known as the Rod-Cone Dystrophies), which results from the loss of rod cells and later the cone cells, Cone-Rod Dystrophies can reflect the opposite sequence of events, where cone cells are primarily first affected with later loss of rods. The degree of vision loss becomes more severe over time. There are multiple types of Cone-Rod Dystrophies, which are determined by their genetic cause and pattern of inheritance.

[0009] Atrophic age-related macular degeneration (AMD) or advanced dry AMD, is an advanced form of age-related macular degeneration that can result in the progressive and irreversible loss of retina (photoreceptors, retinal pigment epithelium, choriocapillaris) which can lead to a loss of visual function over time (22, 23, 24, 25). It is estimated that atrophic AMD affects more than 5 million people worldwide and approximately 1 million patients in the US (26, 27), which is similar to the prevalence of neovascular (wet) AMD, the other advanced form of the disease.

[0010] In patients suffering from RCD, in particular from RP, vision loss develops in three successive steps.

[0011 ] RP patients initially present with loss of vision under dim-light conditions (night vision loss), corresponding to the loss of function and degeneration of rods with relative preservation of macular cone-mediated vision. This is felt as a minor handicap, where patients retain an almost normal way of life (19). [0012] The disease then progresses through a second more incapacitating step resulting from the loss of function and degeneration of cones. In this later stage of the degeneration, cones degenerate in the periphery leading to the well-known tunnel vision. Indeed, the center of the retina represents 5% of all photoreceptors in human and most mammals, and when this part is conserved, patients maintain a high acuity but restricted field of vision (20). [0013] The final stage of the disease corresponds to the degeneration of the foveolar cone photoreceptors, which leads to a total loss of vision in the patient. In this stage, some of the cones present viable cell bodies despite the degeneration of their light sensing outer segments. [0014] In modern society, in which much of the environment is artificially lit, and many activities rely on high acuity color vision, thus the retention of cone-mediated sight in RP patients would lead to a significant improvement in quality of life.

[0015] The loss of cones in RP subsets caused by rod-specific mutations is not perfectly understood, although several mechanisms, which are not necessarily mutually exclusive, have been proposed. Some hypothesized mechanisms implicate a ‘bystander effect’ whereby cone death is a consequence of the release of toxic byproducts from the degeneration of surrounding rods, or as a result of the loss of contact with rods, retinal pigment epithelium (RPE) or Muller glia. Alternatively, activation of Muller cells and the release of toxic molecules may play a role. Another hypothesis is that the quantities of oxygen or retinoids delivered to the photoreceptor layer by the RPE from the choroidal blood circulation are excessive and toxic as the metabolic load of rods is lost (2). Punzo et al. showed evidence that in murine models of retinal degeneration cones die in part as a result of starvation and nutritional imbalance, driven by the insulin/mammalian target of rapamycin pathway (3). Additionally, it has been suggested that the loss of a survival factor secreted by rods and required for cone survival may contribute to cone loss (4, 5).

[0016] In agreement with the last hypothesis, transplanted healthy retinal tissue has been shown to support cone survival in areas distant from the grafted tissue in the rd1 mouse (6, 7). [0017] International patent application W02008/148860A1 describes a family of trophic factors, called rod-derived cone viability factor (RdCVF) and RdCVF2 that are able to increase neuron survival and are useful for treating and/or preventing neurodegenerative disorders such as RP.

[0018] The rod-derived cone viability factor (RdCVF) was originally identified from a high- throughput method of screening cDNA libraries as a candidate molecule responsible for this rescue effect (4). Rods secrete RdCVF, and therefore, as rods die, the source of this paracrine factor is lost and RdCVF levels decrease. The loss of expression of RdCVF, and secreted factors like it, may therefore contribute to the secondary wave of cone degeneration observed in rod-cone dystrophies. [0019] RdCVF has been shown to mediate cone survival both in culture (8) and when injected subretinally in mouse and rat models of recessive and dominant forms of retinitis pigmentosa (4, 9). In 2010, Leveillard and Sahel (21 ) have shown that expression of RdCVF preserves cone-mediated vision by allowing the maintenance of cone outer segments, thereby increasing cone functional life. [0020] Besides, it has been shown that disruption of NxnM , the gene encoding RdCVF, renders mouse photoreceptors increasingly susceptible to photoreceptor dysfunction and cone loss over time (10).

[0021] NxnM encodes two protein isoforms through differential splicing. The isoform mediating cone survival, RdCVF is a truncated thioredoxin-fold protein of its longer counterpart, RdCVFL, which includes a C-terminal extension conferring enzymatic thiol- oxidoreductase activity (11). RdCVFL, which contains all the amino acids of RdCVF, is encoded by exons 1 and 2 of the NxnM gene and is a member of the thioredoxin family (12). Thioredoxins have diverse functions, including maintaining the proper reducing environment in cells and participating in apoptotic pathways. These functions are accomplished via thioloxidoreductase reactions mediated by a conserved CXXC catalytic site within a thioredoxin fold (13).

[0022] Byrne et al. (14) have shown that the two isoforms of encoding by NxnM have complementary functions. Systemic administration of an adeno-associated virus (AAV) encoding RdCVF improved cone function and delayed cone loss, while RdCVFL increased rhodopsin mRNA and reduced oxidative stress. RdCVFL prevents photo-oxidative damage to the rods (16).

[0023] International patent application WO 2016/185037 describes AAV vectors encoding both the short isoform RdCVF and the long isoform RdCVFL and the use of said vectors for treating retinal neurodegenerative pathologies such as retinitis pigmentosa.

[0024] A beneficial effect between RdCVF and RdCVFL has been demonstrated (15). On the one hand, RdCVF is produced and secreted by the retinal pigmented epithelium (RPE), protecting the cones by stimulating aerobic glycolysis through the RdCVF receptor at the cell surface of the cones by a non-cell autonomous mechanism (17). On the other hand, RdCVFL, protects the cones against oxidative damage in a cell autonomous manner, due to its thioloxidoreductase function.

[0025] Recently, it has been shown that the expression of G protein coupled inwardly rectifying potassium channel 2 (GIRK2) can delay vision loss, by preserving cone light- sensitivity in rd10 and RhoP347S mice and enhance visual acuity (18). Dormant cones, which are cones that have diminished outer segments and thus that became dysfunctional, could be rendered functional again thanks to the expression of GIRK2. Summary of the invention

[0026] The present invention relates to the combination of a nucleic acid encoding a short isoform of rod-derived cone viability factor (RdCVF), a nucleic acid encoding a long isoform of rod-derived cone viability factor (RdCVFL) and a nucleic acid encoding a G protein- activated Inward Rectifier potassium channel 2 (GIRK2), expressed through one, two or three viral vectors, said vectors may be within a single pharmaceutical composition or within several different pharmaceutical compositions (two or three).

[0027] According to a first aspect, the present invention relates to a pharmaceutical composition comprising one or several viral vectors, wherein said one or several viral vectors comprise a nucleic acid encoding RdCVF, a nucleic acid encoding RdCVFL and a nucleic acid encoding GIRK2.

[0028] In particular, the pharmaceutical composition comprises a single viral vector.

[0029] A second aspect of the invention deals with a viral vector comprising three nucleic acids respectively encoding RdCVF, RdCVFL and GIRK2. [0030] A third aspect of the invention relates to a kit comprising two or three pharmaceutical compositions.

[0031] The invention also relates to a pharmaceutical composition, a viral vector or a kit above mentioned, for the treatment of a retinal degenerative disease.

[0032] The combination of RdCVF, RdCVFL and GIRK2 described in the present application, allows to both preserve cone cells along with keeping them light responsive. This overcomes the light sensitivity loss that occurs when only trophic factors such as RdCVF and RdCVFL, are used, by implementing an additional approach to increase light sensitivity. Detailed description of the invention

[0033] The present invention relates to a single or several viral vectors comprising a nucleic acid encoding a short isoform of rod-derived cone viability factor (RdCVF), a nucleic acid encoding a long isoform of rod-derived cone viability factor (RdCVFL) and a nucleic acid encoding a G protein-activated Inward Rectifier potassium channel 2 (GIRK2), and the use thereof. When several, the viral vectors may be in a single or in separate pharmaceutical compositions such as distributed among two or three pharmaceutical compositions.

[0034] In one aspect, the present invention relates to a pharmaceutical composition comprising one or several viral vectors, said one or several viral vectors comprising a nucleic acid encoding a short isoform of rod-derived cone viability factor (RdCVF), a nucleic acid encoding a long isoform of rod-derived cone viability factor (RdCVFL) and a nucleic acid encoding a G protein -activated Inward Rectifier potassium channel 2 (GIRK2).

[0035] By “one or several viral vectors”, it means that said nucleic acid encoding RdCVF, said nucleic acid encoding RdCVFL and said nucleic acid encoding GIRK2 may be comprised in a single vector or in separate vectors such as 2 or 3 vectors.

[0036] In a particular embodiment, the pharmaceutical composition comprises three viral vectors respectively comprising a nucleic acid encoding RdCVF, a nucleic acid encoding RdCVFL and a nucleic acid encoding GIRK2.

[0037] In a particular embodiment, the pharmaceutical composition comprises two viral vectors wherein the first viral vector comprises a nucleic acid encoding RdCVF and a nucleic acid encoding RdCVFL, and the second viral vector comprises a nucleic acid encoding GIRK2.

[0038] In a particular embodiment, the pharmaceutical composition comprises two viral vectors wherein the first viral vector comprises a nucleic acid encoding RdCVF and a nucleic acid encoding GIRK2, and the second viral vector comprises a nucleic acid encoding RdCVFL.

[0039] In a particular embodiment, the pharmaceutical composition comprises two viral vectors wherein the first viral vector comprises a nucleic acid encoding GIRK2 and a nucleic acid encoding RdCVFL, and the second viral vector comprises a nucleic acid encoding RdCVF.

[0040] In a particular embodiment, the pharmaceutical composition comprises a single viral vector, said single viral vector comprising three nucleic acids respectively encoding RdCVF, RdCVFL and GIRK2.

[0041] In another aspect, the present invention relates to a kit comprising two or three pharmaceutical compositions.

[0042] When the kit comprises two pharmaceutical compositions, each pharmaceutical composition comprises respectively one viral vector as follows:

- a viral vector comprising a nucleic acid encoding RdCVF and a nucleic acid encoding RdCVFL, and a viral vector comprising a nucleic acid encoding GIRK2;

- a viral vector comprising a nucleic acid encoding RdCVF and a nucleic acid encoding GIRK2, and a viral vector comprising a nucleic acid encoding RdCVFL; or

- a viral vector comprising a nucleic acid encoding GIRK2 and a nucleic acid encoding RdCVFL, and a viral vector comprising a nucleic acid encoding RdCVF. [0043] Thus, in a particular embodiment, the invention relates to a kit comprising two pharmaceutical compositions, wherein:

- the first pharmaceutical composition comprises a viral vector which comprises a nucleic acid encoding RdCVF and a nucleic acid encoding RdCVFL, and - the second pharmaceutical composition comprises a viral vector which comprises a nucleic acid encoding GIRK2.

[0044] When the kit comprises three pharmaceutical compositions, each pharmaceutical composition comprises a single viral vector respectively comprising a nucleic acid encoding RdCVF, a nucleic acid encoding RdCVFL, and a nucleic acid encoding GIRK2.

[0045] Thus, in a particular embodiment, the invention relates to kit comprising three pharmaceutical compositions, wherein:

- the first pharmaceutical composition comprises a viral vector, said viral vector comprising a nucleic acid encoding RdCVF, - the second pharmaceutical composition comprises a viral vector, said viral vector comprising a nucleic acid encoding RdCVFL, and

- the third pharmaceutical composition comprises a viral vector, said viral vector comprising a nucleic acid encoding GIRK2. [0046] In a particular embodiment, the present invention relates to a kit comprising two pharmaceutical compositions, wherein:

- the first pharmaceutical composition comprises a viral vector which comprises a nucleic acid encoding RdCVF and a nucleic acid encoding RdCVFL, and

- the second pharmaceutical composition comprises a viral vector which comprises a nucleic acid encoding GIRK2.

[0047] In a particular embodiment, the present invention relates to a kit comprising three pharmaceutical compositions, wherein :

- the first pharmaceutical composition comprises a viral vector, said viral vector comprising a nucleic acid encoding RdCVF, - the second pharmaceutical composition comprises a viral vector, said viral vector comprising a nucleic acid encoding RdCVFL, and

- the third pharmaceutical composition comprises a viral vector, said viral vector comprising a nucleic acid encoding GIRK2. [0048] The pharmaceutical composition according to the present disclosure may further comprise an excipient pharmaceutically acceptable.

[0049] According to the present disclosure, “pharmaceutically acceptable” means that said excipient is generally safe and well tolerated for human or animal use following ocular administration, and should not interfere with the efficacy of the active ingredient (i.e. a viral vector as described in the present disclosure). As example, excipients pharmaceutically acceptable may be isotonic, sterile, saline solutions such as monosodium or disodium phosphate, sodium, potassium, calcium or magnesium chloride and the like or mixtures of such salts. These solutions may further comprise nonionic surfactants such as, e.g., Tween, Pluronic. In a particular embodiment, an excipient pharmaceutically acceptable is a phosphate-buffered saline (PBS) solution or a balanced-salt solution (BSS), even more particularly supplemented with 0.001% Pluronic. [0050] In another aspect, the present invention relates to a viral vector comprising three nucleic acids respectively encoding RdCVF, RdCVFL and GIRK2.

[0051] As used herein, the term Rod-derived Cone Viability Factor (RdCVF) refers to the short isoform encoded by the thioredoxin-like 6 (TXNL6) or Nucleoredoxin-like 1 (NXNL1) gene. It encompasses the RdCVF proteins of any animal species. Typically, the RdCVF proteins according to the present invention can be mammalian RdCVF proteins, including, but not limited to human, mice, rats, non-human primates, cats and dogs.

[0052] Typically, in mice, the short isoform (RdCVF) is a 109 amino-acid long protein references under Uniprot accession number Q91 W38. [0053] In the present application, the short isoform RdCVF is in particular the human short isoform (hRdCVF) as set forth in SEQ ID NO:1 .

[0054] In particular, said short isoform hRdCVF may be encoded by the nucleic acid as set forth in SEQ ID NO:3.

[0055] Alternatively, the nucleic acid encoding the short isoform hRdCVF can be a nucleic acid which differs from SEQ ID NO: 3 but encodes the same amino acid sequence SEQ ID NO:1.

[0056] Suitable nucleic acid sequences include but are not limited to:

- polymorphisms of the cDNA encoding human RdCVF; - combinations of polymorphisms (rare haplotypes) of the cDNA encoding human RdCVF. An example of rare haplotype cDNA is set forth as SEQ ID NO: 6;

- “optimized” sequences in which certain codons are replaced by codons that code for the same amino-acid. Suitable codon-optimized sequences encoding human RdCVF include, but are not limited to, the sequence as set forth in SEQ ID NO: 7;

- homologous sequences. For example, it has been found that the chimpanzee cDNA sequence encoding the short isoform of chimpanzee RdCVF can be used, since it encodes the same amino acid sequence as the human cDNA. The chimpanzee cDNA has the sequence as set forth in SEQ ID NO: 4. [0057] In particular, the short isoform hRdCVF is encoded by a nucleic acid corresponding to a codon-optimized cDNA as set forth in SEQ ID NO:7.

[0058] As used herein, the term “RdCVFL” refers to the long isoform encoded by the thioredoxin-like 6 (TXNL6) or Nucleoredoxin-like 1 (NXNL1) gene. It encompasses the RdCVFL proteins of any animal species. Typically, the RdCVFL proteins according to the present invention can be mammalian RdCVFL proteins, including, but not limited to human, mice, rats, non-human primates, cats and dogs.

[0059] Typically, in mice, the murine long isoform (RdCVFL) is a 217 amino-acid long protein referenced under Q8VC33. [0060] In the present application, the long isoform RdCVFL is in particular the human long isoform (hRdCVFL) having the sequence referenced under accession number Q96CM4 and as set forth in SEQ ID NO:2.

[0061] In particular, said short isoform hRdCVFL may be encoded by the nucleic acid as set forth in SEQ ID NO:5. [0062] Alternatively, the nucleic acid encoding the long isoform hRdCVFL can be a nucleic acid which differs from SEQ ID NO:5 but encodes the same amino acid sequence SEQ ID NO:2.

[0063] Suitable nucleic acid sequences include but are not limited to:

- polymorphisms of the cDNA encoding human RdCVFL or combinations thereof; - “optimized” sequences in which certain codons are replaced by codons that code for the same amino-acid. Suitable codon-optimized sequences encoding human RdCVFL include, but are not limited to, the sequence as set forth in SEQ ID NO:8;

- homologous sequences in other species. [0064] In particular, said short isoform hRdCVFL is encoded by a nucleic acid corresponding to a codon-optimized cDNA as set forth in SEQ ID NO:8.

[0065] As used herein, the term “GIRK2” refers to the G protein-activated Inward Rectifier potassium channel 2. It encompasses the GIRK2 proteins of any animal species. Typically, the GIRK2 proteins according to the present invention can be mammalian GIRK2 proteins, including, but not limited to human, mice, rats, non-human primates, cats and dogs.

[0066] In particular, the GIRK2 protein may be the human GIRK2 sequence as forth in SEQ ID NO:9. [0067] In particular, said human GIRK2 as forth in SEQ ID NO:9 may be encoded by the nucleic acid as set forth in SEQ ID NO:12.

[0068] Alternatively, the nucleic acid encoding the human GIRK2 can be a nucleic acid which differs from SEQ ID NO:12 but encodes the same amino acid sequence SEQ ID NO:9.

[0069] In particular, the GIRK2 protein may be the truncated rat GIRK2 sequence as forth in SEQ ID NQ:10.

[0070] In particular, said truncated rat GIRK2 as forth in SEQ ID NO:10 may be encoded by the nucleic acid as set forth in SEQ ID NO:35. [0071] In particular, the GIRK2 protein may be the mice GIRK2 sequence as forth in SEQ

ID NO:11 .

[0072] Suitable nucleic acid sequences include but are not limited to:

- polymorphisms of the cDNA encoding human GIRK2 or combinations thereof;

- “optimized” sequences in which certain codons are replaced by codons that code for the same amino-acid.

- homologous sequences in other species.

[0073] Examples of cDNA sequences of the transgenes RdCVF, RdCVFL and GIRK2 and amino acids sequences are provided at Table 1 and Table 2. [0074] Table 1 : cDNA sequences of transgenes

[0075] Table 2: Amino acids sequences of transgenes

[0076] Typically, the nucleic acids encoding respectively RdCVF, RdCVFL and GIRK2 are under the control of a promoter that allows the expression of said proteins in the target cells.

[0077] Suitable promoters can be ubiquitous promoters, such as the Chicken beta actin (CBA) promoter, the chicken beta hybrid (CBh) promoter, the cytomegalovirus (CMV) promoter, the CMV/CBA promoter, CAG promoter.

[0078] In particular, the CBh promoter is as set forth in SEQ ID NO: 13.

[0079] Suitable promoters can be promoters that enable the expression in the retina, preferably in retinal pigmented epithelial cells and photoreceptor cells such as cones and rods.

[0080] In one embodiment, the promoter allows nucleic acids expression in retinal pigmented epithelial cells and/or photoreceptor cells. Non-limiting examples are the rhodopsin kinase (GRK) promoters which target the expression in cones and rods, such as GRK1 promoter, GRK1 -93 promoter, IRBP promoter and mCAR promoter.

[0081] In particular, the GRK1 promoter is as set forth in SEQ ID NO: 14.

[0082] In particular, the GRK1 -93 promoter is as set forth in SEQ ID NO: 15.

[0083] In one embodiment, the promoter allows nucleic acids expression in cone photoreceptors. Non-limiting examples are the cone-opsin PR1 .7 promoter and the ProA7 promoter. In one embodiment, the promoter allows nucleic acids expression in cone photoreceptors. Non-limiting examples are cone-opsin PR1 .7 promoter or ProA7 promoter.

[0084] In particular, the PR1.7 promoter is as set forth in SEQ ID NO: 16.

[0085] In particular, the ProA7 promoter is as set forth in SEQ ID NO: 17.

[0086] Table 3 provides particular nucleic acids sequences of the promoters. [0087] Table 3: Promoters sequences

[0088] Typically, the short isoform of the NXNL1 gene is expressed at least by retinal pigmented epithelial cells, and the long isoform of the NXNL1 gene and GIRK2 are expressed at least by cone photoreceptor cells.

[0089] Typically, the expression of the nucleic acid encoding RdCVF is driven by a CBh promoter, in particular as set forth in SEQ ID NO:13.

[0090] Typically, the expression of the nucleic acid encoding RdCVFL is driven by the ProA7 promoter as set forth in SEQ ID NO:17 or the GRK1 promoter as set forth in SEQ ID NO:14.

[0091] Typically, the expression of the nucleic acid encoding GIRK2 is driven by the GRK1- 93 promoter as set forth in SEQ ID NO:15.

[0092] In a particular embodiment, when a viral vector above described comprises two or three nucleic acids encoding RdCVF, RdCVFL and/or GIRK2, each nucleic acid is under the control of a different promoter.

[0093] Typically, when the viral vector comprises three nucleic acids respectively encoding RdCVF, RdCVFL and GIRK2, the nucleic acid encoding RdCVF is under the control of a CBh promoter, the nucleic acid encoding RdCVFL is under the control of a ProA7 promotor or a GRK1 promoter, and the nucleic acid encoding GIRK2 is under the control of a GRK1- 93 promoter.

[0094] In a particular embodiment, when a viral vector above described comprises two or three nucleic acids encoding RdCVF, RdCVFL and/or GIRK2, at least two nucleic acids may be under the control of a same promoter and linked by a nucleic acid sequence encoding a 2A self-cleaving peptide. [0095] 2A self-cleaving peptides, or 2A peptides, is a class of 18-22 amino acids- long peptides, which can induce ribosomal skipping during translation of a protein in a cell. These peptides share a core sequence motif of DxExNPGP (SEQ ID NO:18).

[0096] As examples of 2A self-cleaving peptide P2A (SEQ ID NO:19), T2A (SEQ ID NO:20), E2A (SEQ ID NO:21 ) and F2A (SEQ ID NO:22) may be cited. Sequences are provided at Table 4.

[0097] Table 4: 2A self-cleaving peptides

[0098] In particular, the 2A self-cleaving peptide is the P2A peptide as set forth in SEQ ID NO: 19. In a particular embodiment, this P2A peptide is encoded by the nucleic acid sequence as set forth in SEQ ID NO:23.

[0099] In a particular embodiment, the viral vector above described comprises three nucleic acids respectively encoding RdCVF, RdCVFL and GIRK2, wherein the nucleic acid encoding RdCVF is under control of a promoter, in particular a CBh promoter, the nucleic acid encoding RdCVFL is under control of a promoter, in particular a GRK1 promoter, and it is linked to the nucleic acid encoding GIRK2 by a nucleic acid sequence encoding a 2A self-cleaving peptide, in particular the P2A peptide.

[0100] In a particular embodiment, the viral vector above described comprises three nucleic acids respectively encoding RdCVF, RdCVFL and GIRK2, wherein the nucleic acid encoding RdCVF is under control of a promoter, in particular a CBh promoter, and it is linked to the nucleic acid encoding RdCVFL by a nucleic acid sequence encoding a 2A self cleaving peptide, this latter being linked to the nucleic acid encoding GIRK2 by a nucleic acid sequence encoding a 2A self-cleaving peptide, in particular the P2A peptide.

[0101] In a particular embodiment, the viral vector above described comprises three nucleic acids respectively encoding RdCVF, RdCVFL and GIRK2, wherein the nucleic acid encoding RdCVF is under control of a promoter, in particular a CBh promoter, and it is linked to the nucleic acid encoding GIRK2 by a nucleic acid sequence encoding a 2A self-cleaving peptide, in particular the P2A peptide, this latter being linked to the nucleic acid encoding RdCVFL by a nucleic acid sequence encoding a 2A self-cleaving peptide, in particular the P2A peptide. [0102] As in all AAV vectors, the viral vector according to the invention comprises an ITR sequence in 5’ and an ITR sequence in 3’.

[0103] In a particular embodiment wherein the viral vector comprises two or three nucleic acids encoding RdCVF, RdCVFL and/or GIRK2 and wherein at least two nucleic acids are linked by a nucleic acid sequence encoding a 2A self-cleaving peptide, the nucleic acids are in any order following the 5’ITR. More particularly, the first nucleic acid following the 5’ITR is the nucleic acid encoding RdCVF.

[0104] In a particular embodiment wherein the viral vector comprises three nucleic acids encoding RdCVF, RdCVFL and/or GIRK2 and wherein the nucleic acids are all linked by a nucleic acid sequence encoding a 2A self-cleaving peptide, the first nucleic acid following the 5’ITR is the nucleic acid encoding RdCVF and the second is the nucleic acid encoding RdCVFL.

[0105] In a particular embodiment wherein the viral vector comprises three nucleic acids encoding RdCVF, RdCVFL and/or GIRK2 and wherein the nucleic acids are all linked by a nucleic acid sequence encoding a 2A self-cleaving peptide, the first nucleic acid following the 5’ITR is the nucleic acid encoding RdCVF and the second is the nucleic acid encoding GIRK2.

[0106] In a particular embodiment, the viral vector described in the present disclosure further comprises a posttranscriptional regulatory element (PRE). This is a DNA sequence that, when transcribed, creates a tertiary structure enhancing expression. This type of sequence is commonly used in molecular biology to increase expression of genes delivered by viral vectors.

[0107] In a more particular embodiment, it is a Woodchuck Hepatitis Virus PRE (WPRE), more particularly as set forth in SEQ ID NO:24.

SEQ ID NO:24 cgataatcaacctctggattacaaaatttgtgaaagattgactggtattcttaactatgt tgctccttttacgctatgtggatacgctgctttaatgc ctttgtatcatgctattgcttcccgtatggctttcattttctcctccttgtataaatcct ggttgctgtctctttatgaggagttgtggcccgttgtcaggc aacgtggcgtggtgtgcactgtgtttgctgacgcaacccccactggttggggcattgcca ccacctgtcagctcctttccgggactttcgctttc cccctccctattgccacggcggaactcatcgccgcctgccttgcccgctgctggacaggg gctcggctgttgggcactgacaattccgtggt gttgtcggggaagctgacgtcctttccatggctgctcgcctgtgttgccacctggattct gcgcgggacgtccttctgctacgtcccttcggccct caatccagcggaccttccttcccgcggcctgctgccggctctgcggcctcttccgcgtct tcgccttcgccctcagacgagtcggatctcccttt gggccgcctccccgcatcgg [0108] As used herein, the term “viral vector” has its general meaning in the art. In particular, it encompasses a vector derived from an adeno-associated virus (AAV), a herpesvirus (e.g., herpes simplex virus (HSV)), an adenovirus, a retrovirus, a lentivirus, or a vaccinia/poxvirus.

[0109] In the present disclosure, the expression “adeno-associated virus vector” or “AAV vector” has its general meaning in the art.

[0110] AAV and AAV vectors have been extensively described in the art as suitable vectors for gene delivery.

[0111] Indeed, AAV are non-pathogenic and display a broad range of tissue specificity, depending of their serotype. Typically, AAV according to the present invention are AAV able to target retinal cells.

[0112] Examples of AAV serotypes include, but are not limited to, AAV8, AAV2, AAV5, AAV7, AAV9.

[0113] In a particular embodiment, the AAV is an AAV8 (also referred to as AAV2/8).

[0114] In one embodiment, the AAV and the AAV vector according to the present invention is obtained according to the method described in international patent application WO2012/158757.

[0115] In a particular embodiment, the AAV capsid is obtained according to the method described in patent application US9193956B2.

[0116] The above cited AAVs may comprise a variant VP1 capsid protein, wherein the variant AAV capsid protein comprises an insertion peptide of from 7 amino acids to 11 amino acids in the GH loop of said capsid protein relative to a corresponding parental AAV capsid protein.

[0117] Said insertion peptide may be as set forth in SEQ ID NO:25, SEQ ID NO:26, SEQ ID NO:27, SEQ ID NO:28, SEQ ID NO:29, SEQ ID NO:30, SEQ ID NO:31 , SEQ ID NO:32, SEQ ID NO:33 as described in WO2019/077159 and at Table 5 below.

[0118] The insertion peptide may also be as set forth in SEQ ID NO:34 (28).

[0119] Table 5: Insertion peptide sequences [0120] Further examples of AAV are thus AAV serotypes as above mentioned, comprising such an insertion peptide.

[0121] The insertion peptide may also be as set forth in SEQ ID NO:37 (LAISDQTKHA). Thus, AAV serotypes as above mentioned may comprise an insertion peptide as set forth in SEQ ID NO:37.

[0122] In a particular embodiment, the above cited AAVs may comprise a variant AAV capsid protein as set forth in SEQ ID NO:36.

[0123] In a particular embodiment, the above cited AAVs may comprise a variant AAV capsid protein as described in SEQ ID NO:42 of WO2019104279A1.

[0124] In another aspect, the present invention deals with a pharmaceutical composition above described, a kit above described, or a viral vector above described for the treatment of a retinal degenerative disease. [0125] In the context of the invention, the term "treating" or "treatment", as used herein, means reversing, alleviating, inhibiting the progress of, or preventing the disorder or condition to which such term applies, or one or more symptoms of such disorder or condition (e.g., retinal degenerative diseases).

[0126] In the present application, the term “retinal degenerative disease” encompasses all diseases associated with rods and cones degeneration. It encompasses different subgroups of pathologies: Rod-cone dystrophies, Cone dystrophies, Cone-rod dystrophies, and atrophic age-related macular degeneration.

[0127] Thus, in a particular embodiment, the present invention relates to a pharmaceutical composition above described, a kit above described, or a viral vector above described for treatment of a retinal degenerative disease, wherein said retinal degenerative disease is a rod-cone dystrophy, a cone dystrophy, a cone-rod dystrophy or an atrophic age-related macular degeneration.

[0128] Retinal degenerative diseases include but are not limited to retinitis pigmentosa, age-related macular degeneration, Bardet-Biedel syndrome, Bassen-Kornzweig syndrome, Best disease, choroideremia, gyrate atrophy, Leber congenital amaurosis, Refsum disease, Stargardt disease or Usher syndrome.

[0129] In a particular embodiment, the retinal degenerative disease is a rod-cone dystrophy, more particularly the retinitis pigmentosa. [0130] In a particular embodiment, the pharmaceutical composition, the kit or the viral vector is administered to a patient in need by subretinal injection, intravitreal and suprachoroidal injection. The delivery of the vector may be submacular or subfoveal or a distal bleb from the fovea without detaching said region.

[0131] When the kit is administered, the pharmaceutical compositions of the kit may be administered simultaneously or separately over time.

[0132] The stoichiometry between the pharmaceutical compositions of the kit can be varied to obtain optimal protection and functional restoration.

[0133] The present invention also relates to a method for the treatment of a retinal degenerative disease comprising a step of administering to a patient in need of a therapeutically effective amount of a pharmaceutical composition above described, of a viral vector above described, or of pharmaceutical compositions comprised in kits above described.

[0134] The term "therapeutically effective amount" as used herein means an amount sufficient to achieve a desired biological effect, in this case increasing the neuron viability, and thus to reduce symptoms or progression of the disease in a patient in need. It is understood that the effective dosage will be dependent upon the age, sex, health, and weight of the recipient, kind of concurrent treatment, if any, frequency of treatment, and the nature of the effect desired. Flowever, the preferred dosage can be tailored to the individual subject, as is understood and determinable by one of skill in the art, without undue experimentation. [0135] The present invention also relates to the use of a pharmaceutical composition above described, a kit above described, or a viral vector above described, in the treatment of a retinal degenerative disease.

Brief Description of Drawings Fig. 1

[0136] [Fig. 1] is a map of plasmid 1 : CBh-hRdCVF-ProA7-hRdCVFL-GRK1-93-GIRK2

Fig. 2 [0137] [Fig. 2] is a map of plasmid 2: CBh-hRdCVF-GRK1 -hRdCVFL-GRK1 -93-GIRK2

Fig. 3

[0138] [Fig. 3] is a map of plasmid 3: CBh-hRdCVF-GRK1 -hRdCVFL-P2A-GIRK2 (+WPRE)

Fig. 4 [0139] [Fig. 4] is a map of plasmid 4: CBh-hRdCVF-P2A-hRdCVFL-P2A-GIRK2- (+WPRE)

Fig. 5

[0140] [Fig. 5] is a map of plasmid 5: CBh-hRdCVF-P2A-GIRK2-P2A-hRdCVFL- (+WPRE)

Fig. 6

[0141 ] [Fig. 6] shows the RdCVF, RdCVFL and GIRK expression 48h after transfection of 661 W cells with Plasmids 1 , 2 or 3. (A) RdCVF transcript was quantified using qPCR with the same set of primers for the three plasmids. (B) RdCVFL transcript was quantified using qPCR with the same set of primers for the three plasmids. (C) GIRK2 transcript was quantified using qPCR with the same set of primers for plasmids 1 and 2. GIRK2 transcript was quantified with a second set of primers that are specific for Plasmid 3.

Examples

[0142] Constructs design

[0143] Different plasmids are designed.

[0144] Plasmid 1 : CBh-hRdCVF-ProA7-hRdCVFL-GRK1-93-GIRK2 Plasmid 1 comprises a nucleic acid of SEQ ID NO:7 encoding the human short isoform RdCVF as set forth in SEQ ID NO:1 , under control of a promoter CBh as set forth in SEQ ID NO:13; a nucleic acid of SEQ ID NO:8 encoding the human long isoform RdCVFL as set forth in SEQ ID NO:2, under control of a promoter ProA7 as set forth in SEQ ID NO: 17; and a nucleic acid of SEQ ID NO: 35 encoding the truncated rat GIRK2 as set forth in SEQ ID NO:10, under control of a promoter GRK1 -93 as set forth in SEQ ID NO:15.

[0145] Plasmid 2: CBh-hRdCVF-GRK1 -hRdCVFL-GRK1 -93-GIRK2 Plasmid 2 comprises a nucleic acid of SEQ ID NO:7 encoding the human short isoform RdCVF as set forth in SEQ ID NO:1 , under control of a promoter CBh as set forth in SEQ ID NO:13; a nucleic acid of SEQ ID NO:8 encoding the human long isoform RdCVFL as set forth in SEQ ID NO:2, under control of a promoter GRK1 as set forth in SEQ ID NO:14; and a nucleic acid of SEQ ID NO: 35 encoding the truncated rat GIRK2 as set forth in SEQ ID NO:10, under control of a promoter GRK1 -93 as set forth in SEQ ID NO:15. [0146] Plasmid 3: CBh-hRdCVF-GRK1-hRdCVFL-P2A-GIRK2 - (+WPRE)

Plasmid 3 comprises a nucleic acid of SEQ ID NO:7 encoding the human short isoform RdCVF as set forth in SEQ ID NO:1 , under control of a promoter CBh as set forth in SEQ ID NO:13; a nucleic acid of SEQ ID NO:8 encoding the human long isoform RdCVFL as set forth in SEQ ID NO:2, under control of a promoter GRK1 as set forth in SEQ ID NO:14; which is linked to a nucleic acid of SEQ ID NO: 35 encoding the truncated rat GIRK2 as set forth in SEQ ID NO:10 by a nucleic acid sequence encoding a 2A self-cleaving peptide (P2A) as set forth in SEQ ID NO:23. Plasmid 3 further comprises a WPRE sequence as set forth in SEQ ID NO:24. [0147] Plasmid 4: CBh-hRdCVF-P2A-hRdCVFL-P2A-GIRK2- (+WPRE)

Plasmid 4 comprises a nucleic acid of SEQ ID NO:7 encoding the human short isoform RdCVF as set forth in SEQ ID NO:1 , under control of a promoter CBh as set forth in SEQ ID NO:13; this latter nucleic acid being linked by a nucleic acid sequence encoding a 2A self-cleaving peptide (P2A) as set forth in SEQ ID NO:23, to a nucleic acid of SEQ ID NO:8 encoding the human long isoform RdCVFL as set forth in SEQ ID NO:2, this latter being itself linked to a nucleic acid of SEQ ID NO:35 encoding the truncated rat GIRK2 as set forth in SEQ ID NO:10, by a nucleic acid sequence encoding a 2A self-cleaving peptide (P2A) as set forth in SEQ ID NO:23. Plasmid 4 further comprises a WPRE sequence as set forth in SEQ ID NO:24. [0148] Plasmid 5: CBh-hRdCVF-P2A-GIRK2-P2A-hRdCVFL- (+WPRE)

Plasmid 5 comprises a nucleic acid of SEQ ID NO:7 encoding the human short isoform RdCVF as set forth in SEQ ID NO:1 , under control of a promoter CBh as set forth in SEQ ID NO:13; this latter nucleic acid being linked by a nucleic acid sequence encoding a 2A self-cleaving peptide (P2A) as set forth in SEQ ID NO:23, to a nucleic acid of SEQ ID NO:35 encoding the truncated rat GIRK2 as set forth in SEQ ID NO:10, this latter being itself linked to a nucleic acid of SEQ ID NO:8 encoding the human long isoform RdCVFL as set forth in SEQ ID NO:2, by a nucleic acid sequence encoding a 2A self-cleaving peptide (P2A) as set forth in SEQ ID NO:23. Plasmid 5 further comprises a WPRE sequence as set forth in SEQ ID NO:24.

[0149] In vitro tests

[0150] 661 W cells were transfected using Lipofectamine reagent (Thermo Fisher) with the plasmids 1 , 2 and 3 above described. Each construct was tested in triplicates (three wells/plasmid). [0151] The RNA expression of each of RdCVF, RdCVFL and GIRK2 transgenes was then quantified by RT-qPCR. For that, 48 hours after transfection, RNAs were extracted using the Nucleospin RNA kit (Macherey-Nagel). RNAs were then treated with Turbo-DNAse kit (Thermo Fisher) to remove DNA. Reverse transcriptions were then performed the Supercript Reverse Transcriptase kit (Thermo Fisher) using oligodT primers. Finally, cDNA was amplified with qPCR (SYBR Green, Thermo Fisher) using plasmid-specific primers, that do not amplify endogenous 661 W cells transcripts.

[0152] RdCVF transcript was quantified using qPCR with the same set of primers for the three plasmids. RdCVFL transcript was quantified using qPCR with the same set of primers for the three plasmids. GIRK2 transcript was quantified using qPCR with the same set of primers for plasmids 1 and 2. GIRK2 transcript was quantified with a second set of primers that are specific for Plasmid 3.

[0153] Results of transgenes expression is shown on Figure 6.

[0154] The 3 tested plasmids are able to express the three transgenes.

[0155] In vivo tests

[0156] Plasmids 1 to 5 are packaged into AAV8, and then are tested in vivo in rd10 mice model by subretinal injection.

[0157] Each vector is tested in the left eye of 15 homozygous rd10 mice aged P15. Two doses are tested:

- Group 1 : 5e + 8 vg/eye in 1 mI (vg = viral genome);

- Group 2: 5e + 7 vg/eye in 1 mI.

[0158] The right eye is treated with 1 mI of a phosphate-buffered saline solution (PBS) with pluronic (poloxamers) at 0.001%, as control. [0159] Output measurements are performed at 15 days, 30 days, 2 months and 3 months post-injection.

[0160] Electroretinogram (ERG), optical coherence tomography (OCT) analysis and optokinetic reflex are carried out, along with histological analysis of retinas. Examination of the eye fundus are also performed in mice to check the expression of the transgene. Cited references

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