Compositions and methods for the treatment of disorders related to syntaxin-binding protein 1 deficiency

AAV capsid variants are used to enhance STXBP1 protein expression, addressing the inadequacies of current treatments for STXBP1-related disorders by effectively treating conditions like STXBP1 encephalopathy.

HK40134654APending Publication Date: 2026-07-10VOYAGER THERAPEUTICS INC
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Patent Information

Authority / Receiving Office
HK · HK
Patent Type
Applications
Current Assignee / Owner
VOYAGER THERAPEUTICS INC
Filing Date
2026-04-07
Publication Date
2026-07-10

AI Technical Summary

Technical Problem

Current treatments for STXBP1-related disorders, such as STXBP1 encephalopathy, are inadequate in effectively enhancing STXBP1 protein expression.

Method used

The use of an adeno-associated virus (AAV) capsid variant to deliver compositions that enhance STXBP1 protein expression.

Benefits of technology

Enhances STXBP1 protein expression, potentially treating STXBP1-related disorders like STXBP1 encephalopathy.

✦ Generated by Eureka AI based on patent content.

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Abstract

The disclosure relates to compositions and methods for altering, e.g., enhancing, the expression of STXBP1 proteins via delivery using an adeno-associated virus (AAV) capsid variant. The compositions and methods of the present disclosure are useful in the treatment of subjects diagnosed with, or suspected of having STXBP1 encephalopathy, or another STXBP1-related disorder.
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Description

CN Title: Compositions and Methods for Treating Disorders Associated with Synaptic Fusion Protein-Binding Protein 1 Deficiency CN Abstract: This disclosure relates to compositions and methods for altering, for example enhancing, STXBP1 protein expression via delivery using an adeno-associated virus (AAV) capsid variant. The compositions and methods disclosed herein can be used to treat subjects diagnosed with or suspected of having STXBP1 encephalopathy or other STXBP1-related disorders. 1 Abstract

Claims

CLAIMSWhat is claimed is:1 . An adeno-associated virus (A AV) particle comprising: a) an AAV capsid variant comprising an amino acid sequence having the following formula: [N1]-[N2.]-[N3], wherein:(i) optionally [N1] comprises XI, X2, and X3, wherein at least one of XI, X2, or X3 is G;(ii) [N2] comprises the amino acid sequence of SPH; and(iii) [N3] comprises X4, X5, and X6, wherein at least one of X4, X5, or X6 is a basic amino acid; and b) a viral genome comprising a syntaxin-binding protein 1 (STXBP1)-encoding sequence.

2. The AAV particle of claim 1, wherein the amino acid sequence [N1]-[N2]-[N3] is in hypervariable loop IV of the AAV capsid variant.

3. The AAV particle of claim 1 or claim 2, wherein the AAV capsid variant is an AAV9 capsid variant.

4. The AAV particle of any one of claims 1-3, wherein [N 1] comprises XI, X2, and X3, wherein at least one of XI, X2, or X3 is G.

5. The AAV particle of any one of claims 1-4, wherein [N2]-[N3] comprises the amino acid sequence of SPHSKA (SEQ ID NO: 941).

6. An adeno-associated virus (AAV) particle comprising a viral genome comprising a syntaxinbinding protein 1 (STXBP1)-encoding sequence and an AAV9 capsid variant comprising the amino acid sequence of SPHSKA (SEQ ID NO: 941).

7. The AAV particle of claim 6. wherein the amino acid sequence of SPHSKA (SEQ ID NO: 941) is in hypetvariable loop IV of the AAV9 capsid variant.

8. The AA V particle of claim 6 or claim 7, wherein the amino acid sequence of SPHSKA ( SEQ ID NO: 941) is present immediately subsequent to an amino acid position corresponding to position 455 of SEQ ID NO: 4 or SEQ ID NO: 36.

9. The AAV particle of any one of claims 6-8, wherein the AA V9 capsid variant further comprises one, two, or all of: an N at an amino acid position corresponding to position 452, an E at an aminoacid position corresponding to position 451, and / or a V at an amino acid position corresponding to position 453 of SEQ ID NO: 4.

10. The AA V particle of claim any one of claims 6-9, wherein the AAV9 capsid variant comprises the amino acid sequence of KTENVSGSPHSKAQNQQT (SEQ ID NO: 3272).

11. The AAV particle of any one of claims 6-10, wherein the AAV9 capsid variant comprises:(i) a VP I protein comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 4;(ii) a VP2 protein comprising an amino acid sequence having at least 90% identity' to positions 138-742 of SEQ ID NO: 4; and / or(iii) a VP3 protein comprising an amino acid sequence having at least 90% identity to positions 203-742 of SEQ ID NO: 4.

12. The AAV particle of any one of claims 6-11, wherein the AAV9 capsid variant comprises:(i) a ATI protein comprising an amino acid sequence having at least 95% identity to SEQ ID NO: 4;(ii) a VP2 protein comprising an amino acid sequence having at least 95% identity to positions 138-742 SEQ ID NO: 4; and / or(iii) a VP3 protein comprising an amino acid sequence having at least 95% identity to positions 203-742 of SEQ ID NO: 4.

13. The AAV particle of any one of claims 6-12, wherein the AAV9 capsid variant comprises :(i) a VP I protein comprising an amino acid sequence having at least 99% identity to SEQ ID NO: 4;(ii) a VP2 protein comprising an amino acid sequence having at least 99% identity to positions 138-742 of SEQ ID NO: 4; and / or(iii) a VP3 protein comprising an amino acid sequence having at least 99% identity' to positions 203-742 of SEQ ID NO: 4.

14. The AA V particle of any one of claims 6-13, wherein the AAV9 capsid variant comprises:(i) a VP I protein comprising the amino acid sequence of SEQ ID NO: 4;(ii) a VP2 protein comprising the amino acid sequence of positions 138-742 of SEQ ID NO: 4; and / or(iii) a VP3 protein comprising the amino acid sequence of positions 203-742 of SEQ ID NO:4.

15. The AAV particle of any one of claims 6-13. wherein the AAV9 capsid variant comprises:(i) the amino acid sequence of SPHSKA (SEQ ID NO: 941), wherein the amino acid sequence is present immediately subsequent to an amino acid position corresponding to position 455 of SEQ ID NO: 4:(ii) an E at an amino acid position corresponding to position 451 and a V at an amino acid position corresponding to position 453 of SEQ ID NO: 4; and(iii) no other modifications relative to wild type AAV9.

16. The AAV particle of any one of claims 6-8, wherein the AAV9 capsid variant further comprises one, two, or all of: an E at an amino acid position corresponding to position 451 , an R at an amino acid position corresponding to position 452, and / or a V at an amino acid position corresponding to position 453 of SEQ ID NO: 36.

17. The AAV particle of any one of claims 6-8 and 16, wherein the A.AV9 capsid variant comprises the amino acid sequence of KTERVSGSPHSK.AQNQQT (SEQ ID NO: 3589).

18. The AAV particle of any one of claims 6-8, 16, and 17, wherein the AAV9 capsid variant comprises:(i) a VP I protein comprising an amino acid sequence having at least 90% identity to SEQ ID NO: 36;(ii) a VP2 protein comprising an amino acid sequence having at least 90% identity to positions 138-742 SEQ ID NO: 36; and / or(iii) a VP3 protein comprising an amino acid sequence having at least 90% identity to positions 203-742 of SEQ ID NO: 36.

19. The AAV particle of any one of claims 6-8 and 16-18, wherein the AAV9 capsid variant comprises:(i) a VP I protein comprising an amino acid sequence having at least 95% identity to SEQ ID NO: 36;(ii) a VP2 protein comprising an amino acid sequence liaving at least 95% identity to positions 138-742 SEQ ID NO: 36; and / or(iii) a VP3 protein comprising an amino acid sequence liaving at least 95% identity to positions 203-742 of SEQ ID NO: 36.

20. The AAV particle of any one of claims 6-8 and 16-19, wherein the AAV9 capsid variant comprises:(i) a VP I protein comprising an amino acid sequence having at least 99% identity to SEQ IDNO: 36;(ii) a VP2 protein comprising an amino acid sequence having at least 99% identity to positions 138-742 of SEQ ID NO: 36; and / or(iii) a VP3 protein comprising an amino acid sequence having at least 99% identity to positions 203-742 of SEQ ID NO: 36.

21. The AAV particle of any one of claims 6-8 and 16-20, wherein the AAV9 capsid vanant comprises:(i) a VP I protein comprising the amino acid sequence of SEQ ID NO: 36;(ii) a VP2 protein comprising the amino acid sequence of positions 138-742 of SEQ ID NO: 36; and / or(iii) a VP3 protein comprising the amino acid sequence of positions 203-742 of SEQ ID NO: 36.

22. The AAV particle of any one of claims 6-8 and 16-20, wherein the AAV9 capsid variant comprises:(i) the amino acid sequence SPHSKA (SEQ ID NO: 941 ), wherein the amino acid sequence is present immediately subsequent to an amino acid position corresponding to position 455 of SEQ ID NO: 36;(ii) an E at an amino acid position corresponding to position 451, an R at an amino acid position corresponding to position 452, and a V at an amino acid position corresponding to position 453 of SEQ ID NO: 36; and(iii) no other modifications relative to wild type AAV9.

23. The AAV particle of any one of claims 1-4, wherein [N1]-[N2]-[N3] is present immediately subsequent to a position corresponding to the amino acid position 452 of SEQ ID NO: 982; and wherein the AAV capsid variant comprises an amino acid sequence at least 90% identical, e.g., at least 91%, at least 92%. at least 93%, at least 94%, at least 95%, at least 96%. at least 97%, at least 98%, at least 99%, or 100% identical, to the amino acid sequence of SEQ ID NO: 982, e.g., to positions 203-742 of SEQ ID NO: 982,24. The AAV particle of claim 23, wherein [N1] comprises GHD.

25. The AAV particle of claim 23 or claim 24, wherein [N1] comprises the amino acid G at a position corresponding to position 453, the amino acid H at position 454, and the amino acid D at position 455 of SEQ ID NO: 138 or SEQ ID NO: 982.

26. The AAA7particle of any one of claims 23-25, wherein [N3] comprises KSG.

27. The AA V particle of any one of claims 23-26, wherein the AAV capsid variant comprises:(i) a VP1 protein comprising the amino acid sequence of SEQ ID NO:

982. or an amino acid sequence having at least 90% identity to SEQ ID NO: 982;(ii) a VP2 protein comprising the amino acid sequence of positions 138-742 of SEQ ID NO:982 or an amino acid sequence having at least 90% identity to positions 138-742 SEQ ID NO: 982; or(iii) a AT3 protein comprising the amino acid sequence of positions 203-742 of SEQ ID NO:982 or an amino acid sequence having at least 90% identity to positions 203-742 of SEQ ID NO: 982.

28. The AAV particle of any one of claims 23-27, wherein the AAV capsid variant comprises:(i) a ATI protein comprising the amino acid sequence of SEQ ID NO: 982 or an amino acid sequence having at least 95% identity to SEQ ID NO: 982;(ii) a VP2 protein comprising the amino acid sequence of positions 138-742 of SEQ ID NO: 982 or an amino acid sequence having at least 95% identity to positions 138-742 SEQ ID NO: 982; or(iii) a VP3 protein comprising the amino acid sequence of positions 2.03-742. of SEQ ID NO:

982. or an amino acid sequence having at least 95% identity to positions 203-742 of SEQ ID NO: 982.

29. The AAV particle of any one of claims 23-28, wherein the AAV capsid variant comprises:(i) a VT1 protein comprising the amino acid sequence of SEQ ID NO: 982 or an amino acid sequence having at least 99% identity to SEQ ID NO: 982;(ii) a VP2 protein comprising the amino acid sequence of positions 138-742 of SEQ ID NO: 982 or an amino acid sequence having at least 99% identity to positions 138-742 SEQ ID NO: 982; or(iii) a VP3 protein comprising the amino acid sequence of positions 203-742 of SEQ ID NO: 982 or an amino acid sequence having at least 99% identity to positions 203-742 of SEQ ID NO: 982.

30. The AAV particle of any one of claims 23-29, wherein the AAV capsid variant comprises:(i) a VT1 protein comprising the amino acid sequence of SEQ ID NO: 982;(ii) a VP2 protein comprising the amino acid sequence of positions 138-742. of SEQ ID NO: 982; or(iii) a AT3 protein comprising tiie amino acid sequence of positions 203-742 of SEQ ID NO: 982.

31. The AAV particle of any one of claims 1-30, wherein the viral genome encodes a wildtype STXBP1 protein.

32. The AAV particle of any one of claims 1-31, wherein the viral genome encodes a human STXBP1 protein.

33. The AA V particle of claim 31 or claim 32, wherein the STXBP1 protein comprises the amino acid sequence of SEQ ID NO: 6413.

34. The AAV particle of any one of claims 1-33, wherein the STXBP1 -encoding sequence comprises a nucleotide sequence that is at least 90% identical (e.g., at least 90% at least 91%, at least 92%, at least 93%, at least 94%, at least 95%. at least 96%, at least 97%, at least 98%, at least 99%. or 100% identical) to SEQ ID NO: 6414.

35. The AAV particle of claim 34, wherein the STXBP1 -encoding sequence comprises a nucleotide sequence that is at least 95% identical to SEQ ID NO: 6414.

36. The AAV particle of claim 35, wherein the STXBP1 -encoding sequence comprises a nucleotide sequence that is at least 99% identical to SEQ ID NO: 6414.

37. The AA V particle of claim 36, wherein the STXBP1 -encoding sequence comprises the nucleotide sequence of SEQ ID NO: 6414.

38. The AAV particle of claim 36, wherein the STXBP1 -encoding sequence consists of the nucleotide sequence of SEQ ID NO: 6414.

39. The AAV particle of any one of claims 1-38, wherein the viral genome comprises a promoter operably linked to the STXBP1 -encoding sequence.

40. The AAV particle of claim 39, wherein the promoter is human elongation factor 1a-subunit (EFla), cytomegalovirus (CMV) immediate-early enhancer and / or promoter, chicken β-actin (CBA), CAG, CAG derivative, β glucuronidase (GUSB), or ubiquitin C (UBC), neuron-specific enolase (NSE), platelet-derived growth factor (PDGF), platelet-derived growth factor B-chain (PDGF-P), intercellular adhesion molecule 2 (ICAM-2), synapsin (Syn), synapsin 1 (Sy nl), methyl-CpG binding protein 2 (MeCP2), Ca2+ / cahnoduiin-dependent protein kinage II (CaMKII), metabotropic glutamate receptor 2. (mGluR2). neurofilament light (NFL) or heavy (NFH), p-globm minigene nβ2, preproenkephaiin (PPE), enkephalin (Enk) and excitatory amino acid transporter 2 (EAAT2), glial fibrillary acidic protein (GFAP), myelin basic protein (MBP), a cardiovascular promoter (e.g., aMHC, cTnT, and CMV-MLC2k), a liver promoter (e.g., hAAT, TBG), a skeletal muscle promoter (e.g., desmin, MCK, C512) or a fragment, e.g., a truncation, or a functional variant thereof.41 . The AAV particle of any one of claims 1-40, wherein the viral genome further comprises an inverted terminal repeat (ITR) sequence.

42. The AA V particle of claim 41, wherein the viral genome comprises an ITR sequence positioned 5’ relative to the STXBP1 -encoding sequence.

43. The AAV particle of claim 41 or ciaim 42. wherein the viral genome comprises an ITR sequence positioned 3’ relative to the STXBP1 -encoding sequence.

44. The AAV particle of any of claims 41-43, wherein the viral genome comprises an ITR sequence positioned 5’ relative to the STXBP1 -encoding sequence and an ITR sequence positioned 3’ relative to the STXBP1 -encoding sequence.

45. An adeno-associated virus (AAV) particle comprising a viral genome comprising a syntaxinbinding protein 1 (STXBP1)-encoding sequence and an AAV capsid variant comprising:(i) a VP 1 protein comprising the amino acid sequence of SEQ ID NO: 4;(ii) a VP2 protein comprising the amino acid sequence of positions 138-742 of SEQ ID NO:4; and / or(iii) a VP3 protein comprising the amino acid sequence of positions 203-742 of SEQ ID NO: 4.

46. An adeno-associated virus (AAV) particle comprising a viral genome comprising syntaxinbinding protein 1 (STXBP1 (-encoding sequence and an AAV capsid variant comprising:(i) a VP 1 protein comprising the amino acid sequence of SEQ ID NO: 36;(ii) a VP2 protein comprising the amino acid sequence of positions 138-742 of SEQ ID NO: 36; and / or(iii) a VP3 protein comprising the amino acid sequence of positions 203-742 of SEQ ID NO: 36.

47. A cell comprising the AAV particle of any one of claims 1-46, optionally wherein the cell is a mammalian cell (e.g., an HEK293 cell), an insect cell (e.g., an Sf9 cell), or a bacterial cell.

48. A method of making the AA V particle of any one of claims 1-46, the method comprising:(i) providing a cell comprising the viral genome comprising a STXBP1 -encoding sequence and a nucleic acid encoding the AAV capsid variant; and(ii) incubating the cell under conditions suitable to encapsulate the viral genome in the AAV capsid variant; thereby making the AAV particle.

49. The method of claim 48, wherein:(a) the viral genome comprises the nucleotide sequence of SEQ ID NO: 6414 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, al least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98% , or at least 99% identical) thereto; and(b) the AAV capsid variant comprises:(i) a VP I protein comprising the amino acid sequence of SEQ ID NO: 4 or an amino acid sequence having at least 90% identity (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity) to SEQ ID NO: 4;(ii) a VP2 protein comprising the amino acid sequence of positions 138-742 of SEQ ID NO: 4 or an amino acid sequence having at least 90% identity (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity) to positions 138-742 SEQ ID NO: 4; or(iii) a VP3 protein comprising the amino acid sequence of positions 203-742 of SEQ ID NO: 4 or an amino acid sequence hatring at least 90% identity (e.g., at least 90%, at least 91%, at least 92%, at least 93%, al least 94%, at least 95%, at least 96%, at least 97%, al least 98%, or at least 99% identity) to positions 203-742 of SEQ ID NO: 4.

50. The method of claim 49, wherein the AAV capsid variant comprises the amino acid sequence of SEQ ID NO: 4, the amino acid sequence of positions 138-742 of SEQ ID NO: 4, and / or the amino acid sequence of positions 203-742 of SEQ ID NO: 4.51 . The method of claim 48, wherein:(a) the viral genome comprises the nucleotide sequence of SEQ ID NO: 6414 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%. at least 94%, at least 95%, at least 96%. at least 97%, at least 98%, or at least 99% identical) thereto; and(b) the AAV capsid variant comprises:(i) a VP I protein comprising the amino acid sequence of SEQ ID NO: 36 or an amino acid sequence having at least 90% identity (e.g., at least 90%, at least 91%, at least 92%, al least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity) to SEQ ID NO: 36;(ii) a VP2 protein comprising the amino acid sequence of positions 138-742 of SEQ ID NO: 36 or an amino acid sequence having at least 90% identity (e.g., at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity) to positions 138-742 SEQ ID NO: 36; or(iii) a VP3 protein comprising the amino acid sequence of positions 203-742 of SEQ ID NO: 36 or an amino acid sequence having at least 90% identity (e.g., at least 90%, at least 91%. at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%. or at least 99% identity) to positions 203-742 of SEQ ID NO: 36.

52. The method of claim 51, wherein the AAV capsid variant comprises the amino acid sequence of SEQ ID NO: 36, the amino acid sequence of positions 138-742 of SEQ ID NO:

36. and / or the amino acid sequence of positions 203-742 of SEQ ID NO: 36.

53. The method of claim 48, wherein:(a) the viral genome comprises the nucleotide sequence of SEQ ID NO: 6414 or a nucleotide sequence that is at least 90% identical (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%. at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identical) thereto; and(b) the AAV capsid variant comprises:(i) a VP I protein comprising the amino acid sequence of SEQ ID NO: 982 or an amino acid sequence having at least 90% identity (e.g.. at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity) to SEQ ID NO: 982;(ii) a VP2 protein comprising the amino acid sequence of positions 138-742 of SEQ ID NO: 982 or an amino acid sequence having at least 90% identity (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity) to positions 138-742 SEQ ID NO: 982; or(iii) a VP3 protein comprising the amino acid sequence of positions 203-742 of SEQ ID NO: 982 or an amino acid sequence having at least 90% identity (e.g., at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least 99% identity) to positions 203-742 of SEQ ID NO: 982.

54. The method of claim 53, wherein the AAV capsid variant comprises the amino acid sequence of SEQ ID NO: 982, the amino acid sequence of positions 138-742 of SEQ ID NO: 982, and / or the amino acid sequence of positions 203-742 of SEQ ID NO: 982.

55. The method of any one of claims 48-54, further comprising, prior to step (i), introducing a first nucleic acid molecule comprising the viral genome into the cell.

56. The method of any one of claims 48-55, wherein the cell comprises a second nucleic acid molecule encoding the AAV capsid variant, optionally wherein the method further comprises, prior to step (i), introducing the second nucleic acid molecule into the cell.

57. The method of any one of claims 48-56, wherein the cell comprises a mammalian cell (e.g., anHEK2.93 cell), an insect cell (e.g., an Sf9 cell), or a bacterial cell.

58. A pharmaceutical composition comprising the AAV particle of any one of claims 1-46, and a pharmaceutically acceptable excipient.

59. A pharmaceutical composition comprising the AAV particle of any one of claims 5-22, and a pharmaceutically acceptable excipient.

60. A pharmaceutical composition comprising the AAV particle of any one of claims 9-15 and 45, and a pharmaceutically acceptable excipient.

61. A pharmaceutical composition comprising the AAV particle of any one of claims 16-22 and 46, and a pharmaceutically acceptable excipient.

62. A method of delivering an AAV particle encoding an STXBP1 protein to a subject, comprising administering to the subject an effective amount of the pharmaceutical composition of any one of claims 58-61 or the AAV particle of any one of claims 1-46.

63. The method of claim 62, wherein the subject has, has been diagnosed with having, or is at risk of having a STXBP1 -rela ted disorder, optionally wherein the STXBP1 -related disorder is a STXBP1- related neurodegenerative or neuromuscular disorder.

64. The method of claim 62 or claim 63, wherein the subject has, has been diagnosed with having, or is at risk of having STXBP1 encephalopathy, epileptic encephalopathy, Ohtahara syndrome. developmental encephalopathy, West syndrome, early myoclonic epileptic encephalopathy, Lennox- Gaustaut syndrome, autism (e.g., autism with STXBP1 mutations and optionally further mutations). Dravet syndrome (not caused by mutations in SCN1A), or Rett syndrome phenotype (not caused by mutation of MECP2 or CDKL5).

65. A method of treating a subject having or diagnosed with having an STXBP1 -related disorder, comprising administering to tire subject an effective amount of the pharmaceutical composition of any one of claims 58-61 or the AAVparticle of any one of claims 1-46.

66. A method of treating a subject having or diagnosed with having an STXBP 1 -related disorder, comprising administering to the subject an effective amount of the pharmaceutical composition of claim 59 or the AAV particle of any one of claims 5-22.

67. A method of treating a subject having or diagnosed with having an STXBP 1 -related disorder, comprising administering to the subject an effective amount of the pharmaceutical composition of claim 60 or the AAV particle of any one of claims 9-15 and 45.

68. A method of treating a subject having or diagnosed with having an STXBP 1 -related disorder, comprising administering to the subject an effec tive amount of the pharmaceutical composition of claim 61 or the AAV particle of any one of claims 16-22 and 46.

69. The method of any- one of claims 65-68, wherein the STXBP 1 -related disorderis an STXBP1- related neurodegenerative or neuromuscular disorder.

70. The method of claim 69, wherein the STXBP 1 -related neurodegenerative or neuromuscular disorder is STXBP1 encephalopathy, epileptic encephalopathy, Ohtahara syndrome, developmental encephalopathy, West syndrome, early myoclonic epileptic encephalopathy, Lennox-Gaustaut syndrome, autism (e.g., autism with STXBP 1 mutations and optionally further mutations), Dravet syndrome (not caused by mutations in SCN1A), or Rett syndrome phenotype (not caused by mutation of JMECP2 or CDKL5).

71. A method of treating a subject having STXBP1 encephalopathy or diagnosed with having STXBP 1 encephalopathy, comprising administering to the subject an effective amount of the pharmaceutical composition of any one of claims 58-61 or the AAV particle of any one of claims 1- 46.

72. A method of treating a subject having STXBP 1 encephalopathy or diagnosed with having STXBP1 encephalopathy, comprising administering to the subject an effective amount of pharmaceutical composition of claim 59 or the A AV particle of any one of claims 5-22.

73. A method of treating a subject having STXBP 1 encephalopathy or diagnosed with having STXBP 1 encephalopathy , comprising administering to the subject an effective amount of the pharmaceutical composition of claim 60 or the AAV particle of any one of claims 9-15 and 45.

74. A method of treating a subject having STXBP1 encephalopathy or diagnosed with having STXBP1 encephalopathy, comprising administering to the subject an effective amount of the pharmaceutical composition of claim 61 or the AAV particle of any one of claims 16-22 and 46.

75. The method of any one of claims 62-74, wherein the subject lias one or more mutations in the STXBP1 gene.

76. The method of any one of claims 62-75, wherein the subject has a reduced level of STXBP1 activity as compared to a reference level in a subject who does not have an STXBP1 -related disorder.

77. The method of any one of claims 65-76, wherein the treating results in prevention of progression of the disorder in the subject.

78. The method of any' one of claims 65-77, wherein the treating results in amelioration of at least one symptom of the disorder and / or a change in one or more biomarkers of the disorder.

79. The method of claim 78, wherein the one or more biomarkers comprises an STXBP1 activity or neurofilament light chain.

80. The method of claim 78, wherein the at least one symptom comprises epilepsy, autistic features, ataxia, generalized tremors, dystonia, or a combination thereof.

81. The method of any one of claims 62-80, wherein the subject is a human.

82. The method of any one of claims 62-81, wherein the AAV particle is delivered to a cell, tissue, or region of the CNS, e.g., a region of the brain or spinal cord, e.g., the parenchyma, the cortex, substantia nigra, caudate cerebellum, striatum, corpus callosum, cerebellum, brain stem caudate- putamen, thalamus, superior colliculus, the spinal cord, or a combination thereof, and / or to neurons, e.g. GABAergic neurons, ghttamatergic neurons, or a combination thereof83. The method of any one of claims 62-82, further comprising evaluating, e.g., measuring, the level of STXBP1 expression, e.g., STXBP1 gene expression. STXBP1 niRNA expression, and / or STXBP1 protein expression, in the subject, e.g., in a cell, tissue, or fluid of lire subject84. The method of claim 83, wherein the level of STXBP1 protein expression is measured by an ELISA, a Western blot, or an immunohistochemistry' assay.

85. The method of claim 83 or claim 84, wherein evaluating the level of STXBP1 expression is performed prior to and subsequent to administration of the AAV particle, optionally wherein the level of STXBP1 expression prior to treatment is compared to the level of STXBP1 expression subsequent to administration.

86. The method of any one of claims 83-85, comprising evaluating the level of STXBP1 expression in a cell or tissue of the central nervous system (e.g., parenchyma).

87. The method of any one of claims 83-86. wherein the subject’s level of STXBP1 protein expression subsequent to administration is increased relative to the subject’s level of STXBP1 protein expression prior to administration.

88. The method of any one of claims 62-87, further comprising evaluating, e.g., measuring, the level of STXBP1 activity in the subject, e.g., in a cell or tissue of the subject.

89. The method of any one of claims 62-88, wherein the administration results in an increase in:(i) STXBP1 activity in a cell, tissue, (e.g., a cell or tissue of the CNS, e.g., the cortex, striatum, thalamus, cerebellum, and / or brainstem), and / or fluid (e.g., CSF and / or serum) of the subject, relative to STXBP1 activity in the subject prior to the administration;(ii) viral genomes (VG) per cell level in a CNS tissue (e.g.. the cortex, striatum, thalamus, cerebellum, brainstem, and / or spinal cord) of the subject, relative to the subject’s VG per ceil level in a peripheral tissue; and / or(iii) STXBP1 mRNA expression in a cell or tissue (e.g., a cell or tissue of the CNS, e.g., the cortex, thalamus, and / or brainstem) of the subject, as compared to STXBP1 mRNA expression in the subject prior to the administration.

90. The method of any one of claims 65-89, further comprising administering to the subject an additional agent suitable for treatment or prevention of an STXBP1 -related disorder; optionally wherein the additional agent comprises one or more anti-epileptic drugs (e.g., levetiracetam, phenobarbital, clobazam, topiramate), adrenocorticotropic hormone, or a combination thereof.

91. The method of any one of claims 65-90, further comprising administering an immunosuppressant to the subject.

92. The method of claim 91, wherein the immunosuppressant comprises a corticosteroid (e.g., prednisone, prednisolone, methylprednisolone, and / or dexamethasone), rapamycin, mycophenolate mofetil, tacrolimus, rituximab, and / or eculizumab hydroxy chloroquine.

93. The pharmaceutical composition of any one of claims 58-61 or the A AV particle of any one of claims 1-46, for use in the treatment of an STXBP1 -related disorder; optionally wherein the STXBP1- related disorder is STXBP1 encephalopathy, epileptic encephalopathy, Ohtahara syndrome, developmental encephalopathy, West syndrome, early myoclonic epileptic encephalopathy, Lennox- Gaustaut syndrome, autism (e.g., autism with STXBP1 mutations and optionally further mutations), Dravet syndrome (not caused by mutations in SCN1A), or Rett syndrome phenotype (not caused by mutation of MECP2 or CDKL5).

94. Use of the pharmaceutical composition of any one of claims 58-61 or the AAV particle of any one of claims 1-46 in the manufacture of a medicament for the treatment of an STXBP1 -related disorder; optionally wherein the STXBP1 -related disorder is STXBP1 encephalopathy, epileptic encephalopathy, Ohtahara syndrome, developmental encephalopathy, West syndrome, early myoclonic epileptic encephalopathy, Lennox-Gaustaut syndrome, autism (e.g., autism with STXBP1 mutations and optionally further mutations), Dravet syndrome (not caused by mutations in SCN1 A), or Rett syndrome phenotype (not caused by mutation of MECP2 or CDKL5).