COMPOSITIONS AND METHODS OF TREATING MUSCLE ATROPHY AND MYOTONIC DYSTROPHY

1 . A small interfering RNA (siRNA) conjugate comprising: an anti-transferrin receptor antibody or an antigen binding fragment thereof conjugated to an siRNA, wherein the siRNA hybridizes to a target sequence of human DMPK mRNA, wherein the siRNA comprises a guide strand comprising a nucleic acid sequence selected from a group consisting of SEQ ID NOs: 13463, 14048, 14047, 14049, 14146, 14072, 13478, 14147, 12234, and 14199; wherein the siRNA conjugate mediates RNA interference against the human DMPK mRNA.

2 . The siRNA conjugate of claim 1 , wherein the passenger strand and the guide strand each independently comprises at least one 2′ modified nucleotide, at least one modified internucleotide linkage, or at least one inverted abasic moiety.

3 . The siRNA conjugate of claim 1 , wherein the siRNA conjugate comprises a linker connecting the anti-transferrin receptor antibody to the siRNA.

4 . The siRNA conjugate of claim 4 , wherein the linker is a non-polymeric linker.

5 . The siRNA conjugate of claim 2 , wherein the at least one 2′ modified nucleotide comprises 2′-O-methyl, 2′-O-methoxyethyl (2′-O-MOE), 2′-deoxy, 2′-deoxy-2′-fluoro, 2′-O-aminopropyl (2′-O-AP), 2′-O-dimethylaminoethyl (2′-O-DMAOE), 2′-O-dimethylaminopropyl (2′-O-DMAP), 2′-O-dimethylaminoethyloxyethyl (2′-O-DMAEOE), or 2′-O—N-methylacetamido (2′-O—NMA) modified nucleotide.

6 . The siRNA conjugate of claim 2 , wherein the at least one 2′ modified nucleotide comprises locked nucleic acid (LNA) or ethylene nucleic acid (ENA).

7 . The siRNA conjugate of claim 2 , wherein the at least one modified internucleotide linkage comprises a phosphorothioate linkage or a phosphorodithioate linkage.

8 . The siRNA conjugate of claim 2 , wherein the at least one inverted abasic moiety is at least one terminus.

9 . The siRNA conjugate of claim 1 , wherein the siRNA conjugate has a drug to antibody ratio of from 1 to 4.

10 . A method of treating myotonic dystrophy in a subject in need thereof, wherein the method comprises administering to the subject an appropriate amount of a small interfering RNA (siRNA) conjugate comprising: an anti-transferrin receptor antibody or a fragment thereof conjugated to an siRNA, wherein the siRNA hybridizes to a target sequence of human DMPK mRNA, wherein the siRNA comprises a guide strand comprising a nucleic acid sequence selected from a group consisting of SEQ ID NOs: 13463, 14048, 14047, 14049, 14146, 14072, 13478, 14147, 12234, and 14199; wherein the siRNA conjugate mediates RNA interference against the human DMPK mRNA.

11 . The method of claim 10 , wherein myotonic dystrophy is myotonic dystrophy type 1 (DM1).

12 . A small interfering RNA (siRNA) conjugate comprising an anti-transferrin receptor antibody or an antigen binding fragment thereof conjugated to an siRNA, wherein siRNA molecule hybridizes to a target sequence of the human DMPK mRNA (NM_001288766.1) from positions 1945 to 2699.

13 . The siRNA conjugate of claim 12 , wherein the passenger strand and the guide strand each independently comprises at least one 2′ modified nucleotide, at least one modified internucleotide linkage, or at least one inverted abasic moiety.

14 . The siRNA conjugate of claim 12 , wherein the siRNA conjugate comprises a linker connecting the anti-transferrin receptor antibody to the siRNA.

15 . The siRNA conjugate of claim 14 , wherein the linker is a non-polymeric linker.

16 . The siRNA conjugate of claim 13 , wherein the at least one 2′ modified nucleotide comprises 2′-O-methyl, 2′-O-methoxyethyl (2′-O-MOE), 2′-deoxy, 2′-deoxy-2′-fluoro, 2′-O-aminopropyl (2′-O-AP), 2′-O-dimethylaminoethyl (2′-O-DMAOE), 2′-O-dimethylaminopropyl (2′-O-DMAP), 2′-O-dimethylaminoethyloxyethyl (2′-O-DMAEOE), or 2′-O—N-methylacetamido (2′-O—NMA) modified nucleotide.

17 . The siRNA conjugate of claim 13 , wherein the at least one 2′ modified nucleotide comprises locked nucleic acid (LNA) or ethylene nucleic acid (ENA).

18 . The siRNA conjugate of claim 12 , wherein the siRNA conjugate has a drug to antibody ratio of from 1 to 4.