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Merck Defers Seeking FDA Approval Of Vicriviroc For Treatment-Experienced HIV Patients

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Published: Feb 2, 2010 9:14 pm
Merck Defers Seeking FDA Approval Of Vicriviroc For Treatment-Experienced HIV Patients

On January 20, 2010, Merck announced to investors that it would not pursue FDA approval of vicriviroc as an HIV therapy for treatment-experienced patients at this time – a decision prompted by unsatisfactory clinical trial results.

However, Robert Consalvo, the company’s Director of Global Product Communications & Advocacy Relations, indicated in email correspondence with the Beacon that Merck could revisit evaluating vicriviroc for treatment-experienced individuals at a later date.

Vicriviroc is a type of drug known as a CCR5 antagonist. This means that it acts by preventing the reaction between the virus and the CCR5 protein, which is found on the surface of human cells.

Because HIV requires the CCR5 protein to replicate, the successful action of such a drug would inhibit virus progression.

Despite positive reports of drug effectiveness this fall, vicriviroc has now encountered an obstacle on the road to Food and Drug Administration (FDA) approval.

According to the FAQ released by Merck Investor Relations, “In two Phase 3 studies in this patient population, vicriviroc did not meet the primary efficacy endpoint. These studies enrolled a high percentage of patients who had three or more active drugs in their optimized background therapy regimen.”

Failure to pass Phase 3 trials indicates that among the hundreds to thousands tested who were already on antiretroviral treatment, the drug’s effectiveness was not adequate.

However, evaluation of the drug among treatment-naive patients will proceed as planned. Currently these trials have reached Phase 2.

Only one other drug of the CCR5 antagonist class, Maraviroc, has been FDA approved for use. It has seen limited success so far, likely due to the fact that before the drug is prescribed, patients must first be tested to see if they are infected with a susceptible virus strain.

Vicriviroc is one of Merck’s many new acquisitions as a result of the company’s recent merger with Schering-Plough.

For more information, please see the Merck Investor Relations FAQ.

Photo by Hoggheff aka Hank Ashby aka Mr. Freshtags on Flickr – some rights reserved.
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