By Donald Zuhn

On March 7, 2007, INEX Pharmaceuticals Corp. and Alnylam Pharmaceuticals, Inc. announced that the United States Patent and Trademark Office (USPTO) issued a Notice of Allowance for U.S. Application No. 09/431,594, which covers nucleic acid-lipid compositions.  According to the statement released by INEX, the allowed claims "cover[] cationic liposome compositions that contain oligonucleotides, including double-stranded RNAs such as siRNAs."  INEX and Alnylam will be adding the new patent to previously issued U.S. Patent Nos. 5,976,567; 6,815,432; and 6,858,225, which INEX states cover the "delivery of oligonucleotides with cationic liposomes." 
In an identical release issued by Alnylam, Chief Intellectual Property Counsel Dr. Robert Millman stated that "[g]iven both the newly allowed claims and previously issued patents, we believe that the Wheeler and Semple patent series represent the broadest intellectual property estate covering lipid-based delivery technologies for RNAi therapeutics."  Information about RNA interference (RNAi) can be found here.

The patent issuing from the ‘594 application will contain 28 claims.  The sole independent claim reads as follows:

    A nucleic acid-lipid particle for introducing a nucleic acid into a cell, said particle comprising a cationic lipid, a non-cationic lipid, a conjugated lipid that inhibits aggregations of particles, and a nucleic acid, wherein said nucleic acid is encapsulated in the lipid of said particle and is resistant in aqueous solution to degradation with a nuclease, wherein said particle has a charge ratio of cationic lipid to anionic nucleic acid of 1:1 to 8:1, and wherein:

    said cationic lipid is a member selected from the group consisting of N,N-dioleyl-
N,N-dimethylammonium chloride (DODAC), N,N-distearyl-N,N-dimethylammonium bromide (DDAB), N-(1-(2,3-dioleoyloxy)propyl)-N,N,N-trimethylammonium chloride (DOTAP), N-(1-(2,3-dioleyloxy)propyl)-N,N,N-trimethylammonium chloride (DOTMA), and N,N-dimethyl-2,3-dioleyloxy)propvylamine (DODMA), and a mixture of two or more of the above;

    said non-cationic lipid is selected from the group consisting of DOPE, POPC, and EPC; and

    said conjugated lipid is a PEG-lipid.