Setback for Merck & Co as vicriviroc disappoints in Ph III

Disappointing results from one of US drug major Merck & Co's pipeline candidates, vicriviroc, are a setback for the company. The drug did not meet the primary efficacy endpoint in two Phase III clinical trials with HIV patients who have already been treated with other products. Following this, Merck said it has shelved plan to seek marketing approval for the drug, which came with its $68 billion acquisition of fellow drug major Schering-Plough last year.

Earlier, results from a mid-stage trial of vicriviroc in treatment-experienced patients found that the drug was being well tolerated and was effective during the two years of therapy. Merck will continue Phase II studies of the drug in treatment-naive HIV patients, for which patient enrollment is complete. Analysts at Zacks Equity research said they had high hopes for the compound.

The Zacks analysts not that Merck's other HIV drug Isentress (raltegravir) is approved in combination with other antiretroviral agents for the treatment of HIV infection in treatment-experienced as well as previously untreated patients. The drug recorded worldwide sales of $179 million for the third quarter of 2009, an increase of 84% compared with the year-ago period. The HIV market is highly competitive with products such as Selzentry (maraviroc) from Pfizer, Intelence (etravirine, ETV, TMC-125) and Viread (tenofovir disoproxil fumarate) of Johnson & Johnson, and Atripla (efavirenz tenofovir emtricitabine) and Truvada (tenofovir/emtricitabine) from Gilead Sciences.