Pfizer's Maraviroc to Receive Accelerated Regulatory Reviews in the U.S. and Europe

Pfizer announced today that marketing authorization applications for maraviroc will receive accelerated review in both the United States and Europe. Accelerated reviews are granted to potential medicines that, if approved, would represent significant improvements over current therapies.

If approved by the regulatory agencies, maraviroc will be the first in a new class of HIV/AIDS treatments called CCR5 antagonists that work by blocking viral entry. Rather than fighting HIV inside white blood cells, CCR5 antagonists prevent the virus produced by infected cells from entering uninfected cells by blocking its predominant entry route, the CCR5 co- receptor.

"There is a profound global need for new medicines to help HIV/AIDS patients," said John LaMattina, president, Pfizer Global Research and Development. "We expect that CCR5 antagonists, like maraviroc, will become critically important new treatment options for patients who are resistant or intolerant to their current HIV/AIDS therapies."

The U.S. Food and Drug Administration (FDA) priority review process takes place within a six-month period. Pfizer submitted the U.S. and EU maraviroc marketing applications in December 2006. An FDA Advisory Panel is scheduled for April 24. Pfizer has begun pursuing regulatory approval for maraviroc in other countries to enable broad access to the drug.

Moving with Urgency

The discovery of maraviroc dates back to 1997 when Pfizer research scientists in Sandwich, UK designed the molecule following the publication of two significant research findings. A study was published in 1996 that described resistance to HIV-1 infection in certain Caucasian subjects, and in the same year, another journal reported the binding of HIV to the CCR5 receptor. Scientists noted that about one percent of Europeans who lacked the genes for CCR5 receptors were the very ones who were resistant to acquiring HIV infection. This finding suggested that blocking the virus's entry through this gateway may lead to a breakthrough therapy. Based on these emerging scientific insights and patient need, the maraviroc team significantly accelerated development time.

"This is the kind of targeted science that underscores our commitment to research and development in a range of infectious diseases where there is high human cost due to drug resistance," said Dr. Ethan Weiner, senior vice president, Pfizer Global Research and Development. "Maraviroc is an outstanding example of rapid development and continuous innovation through which Pfizer researchers quickly translated a scientific hypothesis into a promising compound in this area of great medical need."

Maraviroc is the seventh Pfizer new drug application to receive "Priority Review" status from the FDA over the past two years. Other priority review FDA approvals include Sutent for advanced kidney cancer and gastrointestinal stromal tumors, Chantix for smoking cessation, Revatio for pulmonary arterial hypertension, and Macugen for age-related macular degeneration which can lead to blindness in elderly patients.

Pivotal Trials

The marketing applications follow Pfizer's review of efficacy and safety data from two pivotal phase 3 trials. The trials, MOTIVATE-1 and 2 (Maraviroc plus Optimized Therapy In Viremic Antiretroviral Treatment-Experienced patients), represent 24-week data comparing Optimized Background Therapy, with or without maraviroc, in over 1,000 highly treatment-experienced patients with CCR5-tropic HIV-1. These study results have been accepted for presentation at an upcoming HIV conference.

In addition, the independent Data Safety Monitoring Board (DSMB) for maraviroc met on January 15, 2007 and continues to monitor the ongoing clinical program. The DSMB recommended that the maraviroc Phase 3 registrational trials, in both treatment-naïve and treatment-experienced patients, continue as currently designed.

Update on Expanded Access Program

In December 2006, Pfizer announced plans to establish a multi-national Expanded Access Program to provide maraviroc to patients with limited available treatment options based on its safety and efficacy observed in clinical trials to date. The program is now open for enrollment with a target to enroll patients from over 30 countries.

Through partnerships and focused philanthropic efforts, Pfizer strives to support HIV prevention efforts, build improved healthcare infrastructure, and further access to HIV/AIDS medicines. 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® Partnership Program. For more information on these and other Pfizer initiatives, go to http://www.pfizer.com/