iRNA AGENTS WITH BIOCLEAVABLE TETHERS

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The invention relates to iRNA agents, which preferably include a monomer in which the ribose moiety has been replaced by a moiety other than ribose that further includes a tether having one or more linking groups, in which at least one of the linking groups is a cleavable linking group. The tether in turn can be connected to a selected moiety, e.g., a ligand, e.g., a targeting or delivery moiety, or a moiety which alters a physical property. The cleavable linking group is one which is sufficiently stable outside the cell such that it allows targeting of a therapeutically beneficial amount of an iRNA agent (e.g., a single stranded or double stranded iRNA agent), coupled by way of the cleavable linking group to a targeting agent—to targets cells, but which upon entry into a target cell is cleaved to release the iRNA agent from the targeting agent.

What is claimed is: 
     
         1 . A modified RNA agent comprising a sense strand and an antisense strand, wherein one or more ribose replacement modification subunit (RRMS) comprising a cell-permeation peptide or a cell-targeting ligand is incorporated into at least one of said strands via a phosphatase-cleavable linking group, and wherein the RRMS is a cyclic or acyclic carrier. 
     
     
         2 . The modified RNA agent of  claim 1 , wherein the RRMS is a cyclic carrier selected from the group consisting of hydroxyproline, piperidine, morpholine, piperazine, and decalin/indane. 
     
     
         3 . The modified RNA agent of  claim 1 , wherein the RRMS is an acyclic carrier based on the backbones selected from the group consisting of serinol and bis(hydroxyalkyl)amine. 
     
     
         4 . The modified RNA agent of  claim 1 , wherein the phosphatase-cleavable linking group is a phosphate-based linking group. 
     
     
         5 . The modified RNA agent of  claim 4 , wherein the phosphate-based linking group is selected from the group consisting of —O—P(O)(OR k )—O—, —O—P(S)(OR k )—O—, —O—P(S)(SR k )—O—,
 —S—P(O)(OR k )—O—, —O—P(O)(OR k )—S—, —S—P(O)(OR k )—S—, —O—P(S)(OR k )—S—, 
 —S—P(S)(OR k )—O—, —O—P(O)(R k )—O—, —O—P(S)(R k )—O—, —S—P(O)(R k )—O—, —S—P(S)(R k )—O—, 
 —S—P(O)(R k )—S—, and —O—P(S)(R k )—S—, wherein R k  at each occurrence is, independently, H, C 1 -C 10  alkyl, C 1 -C 10  haloalkyl, C 6 -C 10  aryl, or C 7 -C 12  aralkyl. 
 
     
     
         6 . The modified RNA agent of  claim 4 , wherein the phosphate-based linking group is selected from the group consisting of —O—P(O)(OH)—O—, —O—P(S)(OH)—O—, —O—P(S)(SH)—O—,
 —S—P(O)(OH)—O—, —O—P(O)(OH)—S—, —S—P(O)(OH)—S—, —O—P(S)(OH)—S—, —S—P(S)(OH)—O—, 
 —O—P(O)(H)—O—, —O—P(S)(H)—O—, —S—P(O)(H)—O—, —S—P(S)(H)—O—, —S—P(O)(H)—S—, and 
 —O—P(S)(H)—S—. 
 
     
     
         7 . The modified RNA agent of  claim 1 , wherein the RRMS is incorporated into the sense strand. 
     
     
         8 . The modified RNA agent of  claim 7 , wherein the RRMS is incorporated into the 3′ end of the sense strand. 
     
     
         9 . The modified RNA agent of  claim 8 , wherein the RRMS is placed within 1, 2, or 3 positions of the 3′ end of the sense strand. 
     
     
         10 . The modified RNA agent of  claim 1 , wherein the RRMS is incorporated into the antisense strand. 
     
     
         11 . The modified RNA agent of  claim 10 , wherein the RRMS is incorporated into the 3′ end of the antisense strand. 
     
     
         12 . The modified RNA agent of  claim 1 , wherein the sense strand and the antisense strand are independently 17 to 25 nucleotides in length. 
     
     
         13 . The modified RNA agent of  claim 1 , wherein the modified RNA agent includes a duplex region between 17 and 23 pairs in length. 
     
     
         14 . The modified RNA agent of  claim 1 , wherein the modified RNA agent includes at least one 3′ overhang of 2-3 nucleotides in length. 
     
     
         15 . The modified RNA agent of  claim 1 , wherein the cell-permeation peptide or cell-targeting ligand is selected from the group consisting of an α-helical linear peptide, a disulfide bond-containing peptide, a peptide containing only one or two dominating amino acids, and a bipartite amphipathic peptide. 
     
     
         16 . The modified RNA agent of  claim 1 , wherein the cell-permeation peptide or cell-targeting ligand is an RGD peptide or its variants, or a ligand that targets an integrin. 
     
     
         17 . The modified RNA agent of  claim 16 , wherein the cell-permeation peptide or cell-targeting ligand is an RGD peptide or a ligand that targets the alpha- V  beta-3 integrin. 
     
     
         18 . The modified RNA agent of  claim 1 , wherein at least two RRMS subunits are incorporated into at least one of said strands. 
     
     
         19 . The modified RNA agent of  claim 18 , wherein at least two RRMS subunits are incorporated into the sense strand. 
     
     
         20 . The modified RNA agent of  claim 18 , wherein at least two RRMS subunits are incorporated into the antisense strand.