Drug companies race to develop HIV CCR5 inhibitors

The world's leading drugmakers are racing to be first to market with a new kind of pill that can block HIV virus before it enters human cells, experts said on Wednesday. If successful, so-called CCR5 inhibitors should have fewer toxic side effects and offer hope to patients whose virus has developed resistance to existing antiretroviral medicines. Pfizer, with a product already in final Phase III tests, is a few months ahead, but both GlaxoSmithKline and Schering-Plough are on its tail. CCR5 inhibitors work by blocking a key portal on the surface of immune system cells HIV must latch on to in order to infect the cells. With the portal blocked, the virus is unable to penetrate the cells and make copies of itself. Graeme Moyle, an HIV expert at the Chelsea and Westminster Hospital in London, said he expected the first CCR5 drugs to reach the market in 2007 or 2008. "We need these drugs," Moyle told reporters. "We have downsides with the medications we have at present in terms of toxicity, in terms of patient adherence, and in terms of the management of virus resistance, which makes the need for new drug classes absolutely critical." Moyle said CCR5 pills from all three companies showed similar effectiveness in early tests and were as good as the best existing drugs in reducing levels of virus in the blood. More information on their performance is expected at the 12th Conference on Retroviruses and Opportunistic Infections to be held February 22-25 in Boston. (Reuters, with additional reporting by Advocate.com)