Benitec's three-pronged RNA attack on HIV
patients in the first ever human trial of its RNA therapy, which
attacks HIV on three separate fronts.
During a talk at this week's International Aids Society (IAS) meeting in Sydney, Dr John Rossi from the Beckman Research Institute, City of Hope, California, outlined Benitec's RNA interference (RNAi) therapy, which he has collaborated on, and said that the first patient in the Phase I clinical trial will be dosed "sometime this week." Although HIV/AIDS can build up resistance to existing drugs alarmingly quickly, Rossi explained that attacking the virus on three fronts could enable the drug to fend off resistance for longer; it's easy to mutate around one thing but much more difficult if there's three to contend with. Also, the mutations that he has observed so far "make the virus weak," he said, and it later reverts back to the original sequence. He explained that the drug uses a lentivirus vector to deliver genes that encode for three different forms of RNA to battle the virus: RNAi in the form of short hairpin RNA (shRNA) that targets an exon in the transactivator of transcription (Tat) and Regulator of Virion (Rev) gene (shI), a decoy for the HIV TAT-reactive element (TAR), and a ribozyme that targets the host cell CCR5 chemokine receptor (CCR5RZ). The scientists are using two different techniques to introduce the DNA into the body. The first one is where they remove a patient's own bone marrow progenitor cells, genetically modify them using the virus and then reinfuse them into the patient during a bone marrow transplant. The company claims that "if successful, the new treatment could allow patients' bodies to produce HIV-resistant white blood cells indefinitely." Benitec and City of Hope are also using a similar approach, only with T cells instead of stem cells explained Rossi. He went on to explain that the anti-CCR5 ribozyme may prevent the virus from entering the cell but if it does get in and start to produce RNAs, the drug will capture that RNA and also move Tat away from the virus. Not only does the drug attempt to knock back virus levels, Rossi said it also aims to destroy the lymphoma that develops in many HIV-positive patients. The trial itself will be treating five patients in this subgroup, with the results expected within a year.
