Pfizer and Monogram Collaborate on HIV Tropism Assay

Pfizer Inc. (New York, NY, USA) and Monogram Biosciences (South San Francisco, CA, USA) have announced a non-exclusive collaboration to make Monogram's HIV co-receptor tropism assay available for use on a global basis. The assay is a diagnostic tool to show tropism, the path taken by the virus to access human CD4 cells.

CD4 or T-cells are specialized immune cells that help protect the body from infection. HIV attacks these types of cells and uses them to make more copies of HIV. In doing so, the CD4 cell becomes unable to do its job of protecting the body. At first, the body can make more T-cells but eventually the number of working T-cells decreases. This weakens the immune system and leaves the body at risk for different types of infections.

Tropism information helps identify patients most likely to respond to CCR5 antagonists. These are a class of drugs designed to block viral entry through the CCR5 co-receptor. Studies have shown that 80-85% of patients newly diagnosed with HIV and previously untreated with HIV therapy have the dominant CCR5-tropic virus. This drops to 50-60% in patients who have been treated before with anti-retroviral medicines.

Pfizer has a CCR5-antagonist, maraviroc, in phase III development and has used the Monogram tropism assay to select patients for enrollment in late-stage clinical studies. The agreement expands this clinical trial collaboration and provides for global availability of Monogram's assay in a multi-year collaboration.

"CCR5 antagonists have a mechanism of action different from currently approved drugs”, said John LaMattina, president, Pfizer Global Research and Development. "With this collaboration we are working to advance global access to diagnostics that may better access the potential for CCR5 antagonists to fulfill an unmet need.”



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