MODIFIED iRNA AGENTS

Abstract

The invention relates to iRNA agents, which preferably include a monomer in which the ribose moiety has been replaced by a moiety other than ribose. The inclusion of such a monomer can allow for modulation of a property of the iRNA agent into which it is incorporated, e.g., by using the non-ribose moiety as a point to which a ligand or other entity, e.g., a lipophilic moiety. e.g., cholesterol, is directly, or indirectly, tethered. The invention also relates to methods of making and using such modified iRNA agents.

What is claimed is: 
     
         1 - 19 . (canceled) 
     
     
         20 . A modified double-stranded iRNA agent with reduced off-target RNAi silencing activity, comprising:
 a. an antisense strand that is complementary to a target gene; and   b. a sense strand that is complementary to said antisense strand and comprises at least one modified nucleotide in the region corresponding to the target cleavage site, wherein said modified nucleotide is abasic;   
       wherein said reduced-off-target RNAi silencing activity is relative to a corresponding unmodified iRNA agent. 
     
     
         21 . The modified double-stranded iRNA agent of  claim 20 , wherein the modified nucleotide is a 2-deoxy nucleotide. 
     
     
         22 . The modified double-stranded iRNA agent of  claim 20 , wherein the modified nucleotide is at the first position of the cleavage site of the sense strand. 
     
     
         23 . The modified double-stranded iRNA agent of  claim 20 , wherein the modified nucleotide is at the second position of the cleavage site of the sense strand. 
     
     
         24 . The modified double-stranded iRNA agent of  claim 20 , wherein the modified nucleotide is at the third position of the cleavage site of the sense strand. 
     
     
         25 . The modified double-stranded iRNA agent of  claim 20 , wherein the sense strand and antisense strand are each 15 to 30 nucleobases in length. 
     
     
         26 . The modified double-stranded iRNA agent of  claim 20 , wherein the sense strand and antisense strand are each 17 to 25 nucleobases in length. 
     
     
         27 . The modified double-stranded iRNA agent of  claim 20 , wherein the sense strand and antisense strand are each 19 to 23 nucleobases in length. 
     
     
         28 . The modified double-stranded iRNA agent of  claim 20 , wherein the iRNA agent comprises a single-stranded overhang on at least one terminal end. 
     
     
         29 . The modified double-stranded iRNA agent of  claim 28 , wherein the single-stranded overhang consists of 1, 2, or 3 nucleobases. 
     
     
         30 . The modified double-stranded iRNA agent of  claim 20 , wherein the iRNA agent comprises two 21-nucleotide-long strands, wherein the strands form a double-stranded region of 19 consecutive base pairs having a two-nucleotide overhang at the 3′-end, wherein the cleavage site region corresponds to positions 9-12 from the 5′-end of the sense strand. 
     
     
         31 . The modified double-stranded iRNA agent of  claim 30 , wherein the cleavage site region corresponds to position 10 or 11 from the 5′-end of the sense strand. 
     
     
         32 . The modified double-stranded iRNA agent of  claim 30 , wherein the cleavage site region corresponds to position 10 from the 5′-end of the sense strand.