CROI: Maraviroc Has Double Success In Failing HIV Patients

LOS ANGELES, Feb. 28 -- A investigational anti-HIV drug called maraviroc, the first CCR5 inhibitor, significantly outperformed placebo in patients who were failing anti-retroviral therapy, according to interim results from two major phase III trials.

The 24-week data from the ongoing MOTIVATE-1 and MOTIVATE-2 studies had been eagerly awaited since preliminary results released at the International AIDS Conference last summer in Toronto showed a marked benefit for the drug.

The two identically designed studies were "remarkably consistent" in efficacy and safety results, Howard Mayer, M.D., of Pfizer in New London, Conn., told the Conference on Retroviruses and Opportunistic Infections here.

Among patients who were resistant to at least one drug in each of the approved classes of antiretroviral medications, maraviroc sharply reduced viral load, improved the immune system, and was safe and well-tolerated, said Dr. Mayer. The data were from planned interim analyses.

The CCR5 inhibitors block one of the receptors used by HIV to enter the cell. Unlike other anti-retroviral drugs, maraviroc acts on the host cell, rather than HIV.

The drug is only applicable to people infected with a CCR5-tropic virus, about half of all infections.

Dr. Mayer said the MOTIVATE-1 study, in the U.S. and Canada, enrolled 601 people who were randomized to an optimized background therapy consisting of up to six other drugs, plus placebo, maraviroc once a day, or maraviroc twice a day.

At 24 weeks, the study found:

• 60.4% of the twice-daily group and 54.7% of the once-daily group had fewer than 400 copies of viral RNA per milliliter of serum, compared with 31.4% in the placebo group. Both treatment arms were significantly different (P

Dr. Mellors, who was not involved in the research, noted that Pfizer first identified the compound in 2000 and is now part-way through two major phase III trials.

"It's a quite extraordinary development time-line," he said.