Compositions and Methods for Inhibiting Expression of a Mutant Gene

Abstract

The present invention relates to a double-stranded ribonucleic acid (dsRNA) for inhibiting the expression of a mutant gene, comprising a first strand that has a complementary region that is complementary to at least a portion of an RNA transcript of at least part of the mutant target gene and a second strand of the dsRNA complementary or substantially complementary to the first strand. The invention further relates to a pharmaceutical composition comprising the dsRNA and a pharmaceutically acceptable carrier. The pharmaceutical compositions are useful for inhibiting the expression of a target mutant gene, as well as for treating diseases caused by expression of the target gene. The invention also relates to methods for inhibiting the expression of a target mutant gene, as well as methods for treating diseases caused by the expression of the target gene.

1 . A double-stranded ribonucleic acid (dsRNA) for selective inhibition of expression of a mutant K-Ras gene, the dsRNA comprising:
 a first strand that has a complementary region that is complementary to at least a portion of an RNA transcript of at least part of the mutant K-Ras gene; and   a second strand of the dsRNA, wherein the first and second strands are complementary or substantially complementary to each other,   wherein the first and second strands of the dsRNA are 19 to less than 30 nucleotides in length,   wherein the complementary region of the first strand of the dsRNA contains a mismatch relative to the mutant K-Ras gene and at least one more mismatch relative to a wild type form of the mutant K-Ras gene, and   wherein the dsRNA selectively inhibits expression of the mutant K-Ras gene in a mammalian cell relative to the wild-type form of the mutant K-Ras gene.   
     
     
         2 . The dsRNA of  claim 1 , wherein the mismatch relative to the mutant K-Ras gene is at least 2 nucleotides from an end of the first strand. 
     
     
         3 . The dsRNA of  claim 1 , wherein the mutant K-Ras gene comprises a point mutation that is absent from the wild-type form of the K-Ras gene. 
     
     
         4 . The dsRNA of  claim 1 , wherein the first strand comprises a nucleotide mismatch with the second strand. 
     
     
         5 . The dsRNA of  claim 1 , wherein the first and second strands are 23 nucleotides in length. 
     
     
         6 . The dsRNA of  claim 1 , wherein the first and second strands are 21 nucleotides in length. 
     
     
         7 . The dsRNA of  claim 1 , wherein the first and second strands of the dsRNA are 19 to 24 nucleotides in length. 
     
     
         8 . The dsRNA of  claim 1 , wherein the mutant K-Ras gene is an oncogene with a mutation at codon 12. 
     
     
         9 . The dsRNA of  claim 1 , wherein selectively inhibiting expression further comprises the dsRNA having a substantially greater inhibitory effect on expression of the mutant K-Ras gene in the cell than on the wild-type form of the mutant K-Ras gene. 
     
     
         10 . The dsRNA of  claim 1 , wherein the second strand of the dsRNA is from 1 to 4 nucleotides longer than the first strand such that the dsRNA has a 1 to 4 nucleotide single stranded region at either the 5′ or 3′ end of the second strand. 
     
     
         11 . The dsRNA of  claim 1 , wherein the second strand of the dsRNA is from 1 to 4 nucleotides longer than the first strand such that the dsRNA has a 1 to 4 nucleotide single stranded region at the 3′ end of the second strand. 
     
     
         12 . The dsRNA of  claim 1 , wherein the second strand of the dsRNA is from 1 to 2 nucleotides longer than the first strand such that the dsRNA has a 1 to 2 nucleotide single stranded region at either the 5′ or 3′ end of the second strand. 
     
     
         13 . The dsRNA of  claim 1 , wherein the second strand of the dsRNA is from 1 to 2 nucleotides longer than the first strand such that the dsRNA has a 1 to 2 nucleotide single stranded region at the 3′ end of the second strand. 
     
     
         14 . A pharmaceutical composition for selectively inhibiting the expression of a mutant K-Ras gene in a mammal, the composition comprising:
 a dsRNA and pharmaceutically acceptable carrier, wherein the dsRNA comprises:
 a first strand that has a complementary region that is complementary to at least a portion of an RNA transcript of at least part of the mutant K-Ras gene; and 
 a second strand of the dsRNA, wherein the first and second strands are complementary or substantially complementary to each other, 
 wherein the first and second strands of the dsRNA are 19 to less than 30 nucleotides in length, 
 wherein the complementary region of the first strand of the dsRNA contains a mismatch relative to the mutant K-Ras gene and at least one more mismatch relative to a wild type form of the mutant K-Ras gene, and 
 wherein the dsRNA selectively inhibits expression of the mutant K-Ras gene in a mammalian cell relative to the wild-type form of the mutant K-Ras gene. 
   
     
     
         15 . The pharmaceutical composition of  claim 14 , wherein the mismatch relative to the mutant K-Ras gene is at least 2 nucleotides from an end of the first strand. 
     
     
         16 . The pharmaceutical composition of  claim 14 , wherein the mutant K-Ras gene comprises a point mutation that is absent from the wild-type form of the K-Ras gene. 
     
     
         17 . The pharmaceutical composition of  claim 14 , wherein the first strand comprises a nucleotide mismatch with the second strand. 
     
     
         18 . The pharmaceutical composition of  claim 14 , wherein the first and second strands are 23 nucleotides in length. 
     
     
         19 . The pharmaceutical composition of  claim 14 , wherein the first and second strands of the dsRNA are 19 to 24 nucleotides in length. 
     
     
         20 . The pharmaceutical composition of  claim 14 , wherein the mutant K-Ras gene is an oncogene with a mutation at codon 12. 
     
     
         21 . The pharmaceutical composition of  claim 14 , wherein selectively inhibiting expression further comprises the dsRNA having a substantially greater inhibitory effect on expression of the mutant K-Ras gene in the cell than on the wild-type form of the mutant K-Ras gene. 
     
     
         22 . The pharmaceutical composition of  claim 14 , wherein the second strand of the dsRNA is from 1 to 2 nucleotides longer than the first strand such that the dsRNA has a 1 to 2 nucleotide single stranded region at either the 5′ or 3′ end of the second strand. 
     
     
         23 . The pharmaceutical composition of  claim 14 , wherein the second strand of the dsRNA is from 1 to 2 nucleotides longer than the first strand such that the dsRNA has a 1 to 2 nucleotide single stranded region at the 3′ end of the second strand. 
     
     
         24 . The pharmaceutical composition of  claim 14 , wherein the complementary RNA strand is complementary to an RNA transcript of the K-Ras mutant gene. 
     
     
         25 . The pharmaceutical composition of  claim 14 , wherein the dosage unit of dsRNA is in a range of 0.01 to 5.0 milligrams, 0.01 to 2.5 milligrams, 0.1 to 200 micrograms, 0.1 to 100 micrograms, 1.0 to 50 micrograms, or 1.0 to 25 micrograms per kilogram body weight of the mammal. 
     
     
         26 . The pharmaceutical composition of  claim 14 , wherein the dosage unit of dsRNA is in a range of 1.0 to 25 micrograms per kilogram body weight of the mammal. 
     
     
         27 . The pharmaceutical composition of  claim 14 , wherein the mammal is a human. 
     
     
         28 . The pharmaceutical composition of  claim 14 , wherein the pharmaceutically acceptable carrier is an aqueous solution. 
     
     
         29 . The pharmaceutical composition of  claim 28 , wherein the aqueous solution is phosphate buffered saline. 
     
     
         30 . The pharmaceutical composition of  claim 14 , wherein the pharmaceutically acceptable carrier comprises a micellar structure selected from the group consisting of: a liposome, capsid, capsoid, polymeric nanocapsule, and polymeric microcapsule. 
     
     
         31 . The pharmaceutical composition of  claim 30 , wherein the polymeric nanocapsule and polymeric microcapsule comprise polybutylcyanoacrylate. 
     
     
         32 . The pharmaceutical composition of  claim 14 , which is formulated to be administered by inhalation, infusion, injection, or orally. 
     
     
         33 . The pharmaceutical composition of  claim 14 , which is formulated to be administered by intravenous or intraperitoneal injection. 
     
     
         34 . A method for selectively in inhibiting the expression of a mutant K-Ras gene in a cell, comprising introducing into the cell the dsRNA of  claim 1 , and maintaining the cell for a time sufficient to obtain the selective inhibition of expression of the gene. 
     
     
         35 . The method of  claim 34 , wherein the cell is a colon cancer cell. 
     
     
         36 . A method of treating a disease caused by the expression of a mutant K-Ras gene in a mammal, comprising administering to the mammal the dsRNA of  claim 1 . 
     
     
         37 . The method of  claim 36 , wherein the disease is colon cancer.