Pivotal Data Presented at the 14th Conference on Retroviruses and Opportunistic Infections (CROI) LOS ANGELES, March 1 /PRNewswire-FirstCall/ -- At this week's major HIV/AIDS research meeting, Pfizer presented pivotal data of its experimental medicine, maraviroc, which tackles HIV in an entirely new way. A 24 week analysis showed that approximately twice as many patients receiving maraviroc with an optimized background regimen achieved undetectable virus in the blood than if an optimized regimen was given alone. The new data, presented at the 14th Conference on Retroviruses and Opportunistic Infections (CROI), support the accelerated United States and European regulatory review of maraviroc as a treatment for patients infected with HIV that is "CCR5 tropic," -- enters immune cells by a receptor known as CCR5. A test confirms whether a patient is infected with CCR5-tropic HIV. In addition, patients receiving maraviroc and an optimized regimen saw an increase in CD4 cells nearly twice that seen in those receiving optimized regimen alone. Adverse events in the group receiving maraviroc plus an optimized regimen were similar to those receiving an optimized regimen alone when adjusted for duration of exposure. "Data from the two identical studies are remarkably consistent and demonstrate significant decreases in viral load and increases in CD4 cells when maraviroc is added to the standard optimized treatment regimen," said Dr. Howard Mayer, Pfizer's global clinical lead for the maraviroc development program, who also presented the trial results. If approved, maraviroc would be the first new oral class of HIV medicines in more than a decade, meeting the urgent need of HIV patients for new drug classes. Discovered by Pfizer scientists in 1997, maraviroc is an oral medicine that blocks viral entry to human cells. Rather than fighting HIV inside white blood cells, it prevents the virus from entering uninfected cells by blocking its predominant entry route, the CCR5 co-receptor. Recently, regulatory authorities in the U.S., Europe and Canada granted accelerated review of maraviroc. Accelerated reviews are granted to potential medicines that if approved have the potential to fulfill an unmet medical need. Pfizer is also in the process of submitting marketing applications around the world to make maraviroc available globally. The U.S. Food and Drug Administration's Antiviral Drugs Advisory Committee will discuss maraviroc in April. Pfizer is committed to bringing meaningful improvement to the lives of people living with HIV/AIDS and those at risk around the world. This commitment is embodied in Pfizer's products, partnerships, pipeline and philanthropy. Current initiatives include the U.S. Southern States HIV/AIDS Prevention Initiative; the building of the Infectious Disease Institute in Kampala, Uganda; the Pfizer Global Health Fellows Program; and the Diflucan(R) Partnership Program. For more information on these and other Pfizer initiatives, go to http://www.pfizer.com/. Background on data supporting maraviroc The latest results were analyzed at 24 weeks from the ongoing multicenter, double-blind, placebo-controlled phase 2b/3 MOTIVATE trials (Maraviroc Plus Optimized Therapy in Viremic Antiretroviral Treatment Experienced Patients). In both studies, approximately twice as many patients treated with maraviroc plus optimized background therapy (OBT) for either once or twice daily dosing achieved undetectable viral loads (