Isis Pharmaceuticals Inc. has exclusively licensed Vical Inc.'scationic lipids to use for delivery of antisense molecules.Isis (NASDAQ:ISIP) will pay royalties to the privately held genetherapy company, but other terms were not disclosed.Isis scientists have published on the ability of lipids similar toVical's proprietary compounds to enhance the activity ofantisense oligonucleotides in mammalian cells.
The cationic lipids are "much simpler" delivery vehicles thanliposomes or liposomal microspheres, said Robert Zaugg, Vical'ssenior director of business development. Various anticancerdrugs are being delivered by liposomes, while liposomalmicrospheres are being developed to enhance vaccine and painkiller delivery.
With cationic lipids, "you get more of your substance in withless lipid," Zaugg said. Only 10 percent to 20 percent of a drugis incorporated into liposomes, while "virtually 100 percent" ofdrug gets incorporated into cationic lipids, he said.
Although the physico-chemical properties of the lipids are notyet clear, Zaugg said they may help molecules cross into cellsby virtue of their cationic, or positive, charge. Most nucleotidesand proteins are negatively charged, and are repelled by like-charged cell membrane components.
Zaugg noted that Vical of San Diego can deliver its therapeuticgene sequences directly into muscle, but still intends to use thelipid technology to get the genes into non-muscle tissue.
Most gene therapy companies have wrestled with getting theiragents into cells, a hurdle Vical claims to side-step. Now Vical'slipid chemistry will help antisense achieve its therapeuticobjective with "a more basic" delivery system than waspreviously available, said Lynne Parshall, vice president andgeneral counsel for Isis.
Stock of the Carlsbad, Calif., company closed at $12.75, down 75cents, on Wednesday. -- Roberta Friedman, Ph.D.
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