Maraviroc works by blocking the virus from entering uninfected cells through the CCR5 co-receptor.

Pfizer’s HIV/AIDS therapy that blocks viral entry will receive accelerated review of its marketing approval in the U.S. and Europe. If approved, maraviroc will be the first in a new class of HIV/AIDS treatments called CCR5 antagonists. 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.

“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,” John LaMattina, president, Pfizer global R&D.

The FDA’s priority review process takes place within a six-month period as opposed to the usual 10 months. Pfizer says that an FDA advisory panel is scheduled for April 24. It is also pursuing regulatory approval for maraviroc in other countries.

Pfizer’s work on this potential treatment started in 1997. A study in 1996 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. Pfizer scientists noted that about one percent of Europeans who lacked the genes for CCR5 receptors were the ones who were resistant to acquiring HIV infection. This finding prompted them to design a molecule that would block the virus’ entry through this gateway.

The marketing applications follow Pfizer’s review of efficacy and safety data from two pivotal Phase III trials. The trials, MOTIVATE-1 and 2, studied Maraviroc plus optimized therapy in viremic antiretroviral treatment-experienced patients.

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