CROI 2014Promising preliminary results from a trial of Merck’s MK-5172 and MK-8742, given with or without ribavirin, showed that the combination therapy was as safe in treating genotype 1 of hepatitis C virus (HCV) among those coinfected with HIV as it was among those monoinfected with hep C. The treatment appears to boast near-perfect success rates. Results from the C-WORTHY study, which is a Phase II, randomized, dose-responsive, parallel-group, multiple-site, open-label trial comparing various difficult-to-treat populations among a group of 450 people with hep C, were presented at the Conference on Retroviruses and Opportunistic Infections (CROI) in Boston.

The coinfected segment of the study included 59 people coinfected with HIV and genotype 1 of HCV who were treatment naive, did not have cirrhosis and who were taking a stable antiretroviral regimen to treat HIV: Isentress (raltegravir) and Viread (tenofovir) or Ziagen (abacavir) with either Epivir (3TC) or Emtriva (emtricitabine ) These participants were compared with 65 people monoinfected with genotype 1 of hep C. All the participants were randomized to receive the NS3/4A protease inhibitor MK-5172 and the NS5A replication complex inhibitor MK-8742 for 12 weeks either with or without ribavirin.

At the end of treatment, all 29 of the coinfected participants who took ribavirin and 90 percent of those who did not (26/29) had undetectable hep C. Meanwhile, among the monoinfected participants, 94 percent of those who took ribavirin (49/52) and all 13 of those who did not achieved an undetectable viral count.

Twelve weeks must pass after the end of treatment for researchers to determine if a participant has been cured of hep C. Merck intends to present such results at a meeting in the spring.

Of the three coinfected participants who failed treatment, one completed the therapy but was then lost to follow-up, and two others maintained low levels of one or both of MK-5172 and MK-8742 and experienced virologic breakthrough at the eight-week mark during treatment.

The most common adverse side effects were fatigue (7 percent) and headache (8 percent). There was no difference in side effects between the coinfected and monoinfected groups.

To read the Merck press release, click here.