Pfizer and Monogram Biosciences have entered into a non-exclusive collaboration to make Monogram's HIV Co-Receptor Tropism Assay available for patient 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.

Under the terms of the agreement announced, Pfizer and Monogram will collaborate to make Monogram's Co-Receptor Tropism Assay available globally. Pfizer also entered into an agreement to invest $25 million in Monogram this month through a Senior Secured Convertible Note, payable in May 2010.

Tropism information is intended to help identify patients who are most likely to respond to a class of investigational drugs known as CCR5 antagonists. CCR5 antagonists are designed to block viral cell entry through the CCR5 co-receptor.

According to the release, Pfizer has a CCR5 antagonist, maraviroc, in phase 3 development and has used the Monogram tropism assay to select patients for enrolment in late- stage clinical studies. The agreement announced today expands this clinical trial collaboration and provides for global availability of Monogram's assay in a multi-year collaboration.

"Because of the important role the Co-Receptor Tropism Assay is believed to play in CCR5 antagonist clinical development, we are pleased to be expanding our partnership with Pfizer. We look forward to working together so that the right medicine can be made available to the right patients at the right time," said William D.Young, Monogram CEO.

"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 new diagnostics that may better assess the potential for CCR5 antagonists to fulfil an unmet medical need," he added.