Data on experimental anti-HIV drugs released at San Francisco conference

Data on several new anti-HIV drugs in development were released this week at the 11th Conference on Retroviruses and Opportunistic Infections, held in San Francisco. Researchers from GlaxoSmithKline report that data from a Phase I clinical trial of experimental HIV fusion inhibitor 873149 were so encouraging that the company is now enrolling patients in a Phase II trial of the drug. Phase I results showed that the drug completely blocked the CCR5 receptors on the surface of immune system cells that HIV latches onto by 95% to 100% regardless of the dose used. When the receptors are blocked, HIV cannot bind to and infect the cells. The company plans to announce preliminary results from the Phase II trial later this year. Officials from Pharmasset and Incyte report that preliminary results from a Phase II clinical trial of their experimental nucleoside reverse transcriptase inhibitor Reverset showed that the once-daily medication reduced blood-based viral loads by 98% in study patients who took the drug for 10 days. Early tests showed the drug is effective in treating HIV that is resistant to AZT and 3TC. The Phase II trial is ongoing. Schering-Plough announced that early clinical trials of its experimental fusion inhibitor SCH-D showed the drug is safe and well-tolerated. SCH-D binds to the CCR5 receptors on the surface of immune system cells, preventing HIV from latching onto the cells and infecting them. On average, the drug reduced the viral loads of 48 study patients to one fiftieth of their levels prior to treatment. The drug is designed to work for people initially infected with HIV; those whose immune systems are already damaged by HIV tend to have viruses that favor another surface receptor on immune system cells. The company is planning a Phase II trial that will include 200 people. Bristol-Myers Squibb presented data from its Phase I clinical trial of its fusion inhibitor BMS-488043. Patients who took the drug twice a day for eight days had significant reductions in blood-based viral loads and rises in T-cell counts when compared to a placebo group. The drug also was shown to be safe and well-tolerated. A Phase II trial is planned.