TORONTO—Scientists from Pfizer Global R&D presented the results of Phase IIb studies of maraviroc, one of a new class of anti-HIV drugs called CCR5 antagonists. Unlike the predominant retroviral inhibitors, which largely target the virus after it has entered white cells, CCR5 antagonists prevent the virus from entering the cells by blocking its interaction with CCR5, its predominant route of entry.

 

The 24-week study of 186 late-stage patients examined whether maraviroc, when used in combination with a combination therapy, would increase the incidence of HIV infection via another cell receptor (CxCR4) and lead to more rapid diminishing of CD4 cell counts. The scientists found that although viral load reduction was similar between maraviroc and placebo, the CD4 increase was greater in the treatment group, with no indication of further toxicities.

 

The company will use this data in conjunction with ongoing Phase III studies.