Many academic and private-sector RNAi researchers believe that HIV is one of the most promising targets for RNAi-based therapeutic intervention. One of these is Irvin Chen, director of the UCLA AIDS Institute, who has recently begun testing a stem cell-based RNAi treatment in monkeys, and presented in vitro data at the first meeting of the Oligonucleotide Therapeutics Society held in late September in New York City.
Chen conceded that the approach faces significant hurdles, including the prerequisite to destroy a patient’s existing stem cell population through radiation therapy — a risky proposition for individuals with HIV because it could sap their already-weakened immune system.
“I think that RNAi is going to be a good approach for HIV disease,” Chen said. “We have a very discrete target, the virus, and either directly targeting the virus itself or … knocking out a co-receptor for HIV-1 … will be a very effective means of preventing HIV replication.”
According to Chen, the approach he is taking in a proof-of-concept study involves treating a rhesus macaque with cytokines that increase levels of stem cells in the blood. “Basically, [the treatment] mobilizes stem cells from the bone marrow so that they appear in the blood,” he explained. “Then, you can harvest those stem cells, purify them, put in whatever gene therapy reagent you want — say, a vector expressing RNAi — and infuse those back into a patient [intravenously].”
The vector Chen is using expresses an siRNA against CCR5, a co-receptor essential for replication in about 95 percent of all HIV-1 strains, he said. “Experiments [on the importance of CCR5] have already been done in nature — there are people that are naturally resistant to HIV because they lack CCR5. They can’t be infected at all by those strains of HIV that use the co-receptor.”
— Doug Macron
US Patent application 20050215497. Inhibitor oligonucleotides and their use for specific repression of a gene. Inventors: Annick Harel-Bellan, Slimane Ait-Si-Ali, Florence Cabon-Georget, Anne Chauchereau, Francois Dautry, Luis Martinez. Filed: September 27, 2004.
This technology covers “two complementary oligonucleotide sequences forming a hybrid comprising each at one of their 3’ or 5’ ends one to five non-matched nucleotides forming single-stranded ends overlapping from the hybrid, one of said oligonucleotide sequences being substantially complementary of a target sequence belonging to a DNA or RNA molecule to be specifically repressed,” according to the abstract.
US Patent application 20050214851. siRNA knockout assay method and constructs. Inventors: Gert-Jan Arts, Ellen Vera Langemeijer, Ivo Piest, Helmuth Hendrikus Gerardus Van Es, Godefridus Augustinus Maria Michiels. Assignee: Galapagos. Filed: May 13, 2005.
This patent covers isolated polynucleotides and vectors “useful for down-regulation of specific RNA in cells, including a first sequence of about 17 to about 23 nucleotides, complementary to said RNA, and linked to a second sequence capable of forming a loop when said second sequence is RNA.”
GE Healthcare will manufacture microRNA arrays on its CodeLink platform for Ambion, which will market the product. Known as mirVana miRNA microarrays, these include a panel of known human, mouse, and rat miRNAs, as well as proprietary microRNAs from Ambion.
Meanwhile, Ambion signed a deal with Rosetta Genomics to get access to that company’s proprietary microRNA sequences. Under the agreement, Ambion will adapt its platform to detect, quantify, and characterize proprietary microRNA sequences discovered by Rosetta, a developer of microRNA-based therapeutics and diagnostics.
Alnylam Pharmaceuticals and Isis Pharmaceuticals signed a co-exclusive license agreement to acquire IP from Stanford University related to the discovery and development of therapeutics for hepatitis C infection by inhibiting liver-specific microRNAs.
Galapagos will work with Amsterdam Molecular Therapeutics, the Netherlands Institute for Brain Research, and the Vrije Universiteit Amsterdam to develop treatments for acute spinal cord and peripheral nerve damage. Terms of the deal call for the Dutch company to provide access to its siRNA vectors on a fee-for-service basis. The collaboration aims to develop drugs that promote nerve regeneration and reduce the effect of neural scarring.
Sirna Therapeutics could gain as much as $250 million in milestone and other payments as part of a deal with Allergan to develop an RNAi-based therapeutic for age-related macular degeneration. Sirna will also help discover and develop RNAi-based drugs for other ophthalmic diseases.