Merck & Co Inc. (MRK) announced positive results from its Phase 3 clinical trial evaluating the safety and efficacy of its HIV drug, doravirine (MK-1439). The late-stage trial met its primary efficacy endpoint, and generated comparable results which were at par with Johnson & Johnson’s (JNJ) blockbuster HIV drug Prezista (darunavir), which was approved in June 2006.

The trial compared the efficacy of two drug combinations, one comprised of doravirine with tenofovir disoproxil fumarate/emtricitabine (TDF/FTC), and another comprised of ritonavir-boosted darunavir with tenofovir disoproxil fumarate/emtricitabine (TDF/FTC), to treat adults with previously untreated (treatment-naive) HIV-1 infection.

Promising Combo-Drug Results

In the 383-patient study, the results indicate that doravirine cocktail therapy removed all signs of the HIV virus among 83.8% (321/383) participants compared to 79.9% (306/383) participants for the Prezista combination.

“The results of this study provide solid evidence of the efficacy and safety profile of doravirine as a potential treatment option for treatment-naive HIV-1 patients,” said Dr. Kathleen Squires, director of infectious diseases at Thomas Jefferson University in Philadelphia.

Competitive HIV Drug Market

If approved, Merck will get a promising successor to its existing HIV drug, Isentress (raltegravir), which was first approved in October 2007. Isentress has been on the market for the past decade and generates annual revenue of around $1.4 billion.

Merck will face competition from Gilead Sciences Inc.’s (GILD) bictegravir (formerly called GS-9883) and GlaxoSmithKline PLC’s (GSK) two-drug combination comprised of dolutegravir with Johnson & Johnson’s rilpivirine, both of which reported positive results. (For more, see Gilead's HIV Drug Reports Positive Data.)

Gilead’s Genvoya and GSK’s Tivicy (dolutegravir) are the currently approved therapies for HIV. (For more, see Gilead, GlaxoSmithKline Race for HIV Cure.)