Pfizer's Maraviroc, Novel Medicine For HIV, Significantly Reduces Viral Load, in Combination Therapy Across Range of Treatment-Experienced Patients

LOS ANGELES, March 1 /PRNewswire/ --

- Pivotal Data Presented at the 14th Conference on Retroviruses and Opportunistic Infections (CROI)

- Maraviroc Under Accelerated Review in USA and Europe

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 (<50 copies/mL HIV RNA) compared to those receiving placebo plus OBT (MOTIVATE-1, 42.2% and 48.5% respectively versus 24.6%; MOTIVATE-2, 40.8% and 45.6% respectively versus 20.9%). Patients receiving maraviroc with OBT for once or twice daily treatment arms also had significantly higher increases in CD4 cells than patients receiving placebo plus OBT (MOTIVATE-1, 107 cells/mm3 and 111 cells/mm3 respectively versus 52 cells/mm3; MOTIVATE-2, 112 cells/mm3 and 102 cells/mm3 respectively versus 64 cells/mm3).

The groups receiving maraviroc plus OBT in both studies had a low rate of discontinuation due to adverse events regardless of once or twice daily dosing, similar to the group receiving OBT alone (MOTIVATE-1, 5% and 4% respectively versus 5%; MOTIVATE-2, 5% and 4% respectively versus 2%).

In the MOTIVATE 1-2 trials, patients were randomized to receive OBT combined with either placebo or maraviroc, dosed once or twice daily. OBT included 3-6 anti-retrovirals, with or without low-dose ritonavir. The primary endpoint was the mean reduction in HIV-1 RNA from baseline to week 24. MOTIVATE 1 is being conducted at clinical investigational sites in the U.S. and Canada and MOTIVATE 2 in Europe, Australia, and the U.S.

In December 2006, Pfizer announced plans to establish a multi-national Expanded Access Program, a clinical study that provides maraviroc to patients who have limited or no approved treatment options due to resistance or intolerance to existing drug classes. The program is open for enrollment with a target to enroll patients from over 30 countries.

Pfizer is also studying the utility of maraviroc in treatment naive patients who have never undergone any HIV medical treatment in an ongoing study.

The independent Data Safety Monitoring Board (DSMB) for maraviroc met on January 15, 2007 to continue to monitor the ongoing clinical programs. In addition to recommending that the MOTIVATE program continues as currently designed, the DSMB also recommended that the fully enrolled and ongoing maraviroc trial in treatment-naïve patients continue.

DISCLOSURE NOTICE: The information contained in this release is as of March 1, 2007. Pfizer assumes no obligation to update any forward-looking statements contained in this release as the result of new information or future events or developments.

This release contains forward-looking information that involves substantial risks and uncertainties regarding a product candidate that is under review by the United States Food and Drug Administration (FDA), the European Medicines Evaluation Agency (EMEA) and certain other regulatory authorities. Such risks and uncertainties include, among other things, whether and when the FDA, the EMEA and other regulatory authorities will approve the product candidate, their decisions regarding labeling and other matters that could affect its availability or commercial potential, as well as competitive developments.

A further list and description of risks and uncertainties can be found in Pfizer's Annual Report on Form 10-K for the fiscal year ended December 31, 2006 and in its reports on Form 10-Q and Form 8-K.

Web site: http://www.pfizer.com