Merck Decides to Stop Development of Vicriviroc for Treatment of HIV

		SUMMARY: Merck Research Laboratories announced on July 15 that it would discontinue development of its investigational CCR5 antagonist vicriviroc for the treatment of HIV infection in both treatment-naive and treatment-experienced patients, due to unimpressive results in clinical trials. All ongoing studies of the drug, as well as long-term open-label distribution, will be halted.

Researchers presented data at the 17th Conference on Retroviruses and Opportunistic Infections this past February showing that vicriviroc did not demonstrate non-inferiority to an optimized background regimen plus placebo among treatment-experienced participants in the twin VICTOR trials. The drug did perform well for people with fewer active background drugs, however, raising the issue of how the benefits of new drugs should be evaluated in an era of highly effective antiretroviral therapy.

As previously reported, Merck informed investors in January that it did not plan to seek U.S. Food and Drug Administration (FDA) approval of vicriviroc for treatment-experienced patients, but at the time indicated that the company would continue to evaluate the drug as first-line therapy. Merck has now decided to stop testing vicriviroc in this group too, based on data from a Phase 2 trial that will be presented at an upcoming scientific meeting.

In a statement issued July 15, 2010, the company stated:

"Merck has decided to discontinue the development of vicriviroc for the treatment of HIV infection. This decision was based on the overall clinical data from Phase III trials in treatment-experienced patients and a recently completed Phase II trial in treatment-naive patients.

All ongoing clinical studies of vicriviroc, including those that involve long-term open-label distribution of the therapy, will be terminated, and study participants will be transitioned to appropriate available therapies.

Merck has a long-standing commitment to the research and development of innovative therapies for people with HIV that spans nearly 25 years and remains committed to HIV research and to the development of new therapies."

In addition, Lisa Dunkle, Merk's Executive Director of Clinical Research, sent a letter to investigators urging them to wind up ongoing clinical trials as soon as possible.

"You should plan as soon as feasible to bring in all study subjects still receiving vicriviroc for evaluation and for you to determine the best regimen of available antiretroviral agents for them to receive in your location," she wrote. "Where time is required to obtain these agents, Merck will try to work with you to assure a smooth transition, recognizing that we have a limited supply of vicriviroc at this time."

Merck said it will halt development of vicriviroc for the treatment of HIV infection, but did not say whether the company plans to pursue research for other indications.

7/16/10

Sources

Merck. Statement from Merck regarding the development of vicriviroc for the treatment of HIV infection. July 15, 2010.

LM Dunkle. Investigator Letter. July 15, 2010.