- Merck has designed a trial studying two of its drugs, grazoprevir and elbasvir, in combination with Sovaldi (sofosbuvir), in order to establish whether a mere 4-week regimen could provide a high level of cure in hepatitis C (HCV)-infected patients.
- In treatment naive HCV-infected patients treated with this regimen, only 38.7% had no detectable sign of the hep C virus after four weeks—and 19 of the 31 treated patients relapsed before the 12-week mark.
- The best results Merck got out of this trial involved patients with cirrhosis who were treated for eight weeks. Just under 95% of these patients had no detectable virus, but they will not be deemed cured until 12 weeks after stopping treatment.
This is an interesting time in virology, with a great deal of innovation occurring in the treatment of various genotypes of HCV, especially HCV-1. Within the last three years, the duration of treatment has been pushed down from 48 weeks to 8 weeks in some cases (using Gilead's Harvoni (ledipasvir/sofosbuvir).
However, Merck's efforts to further condense that treatment timeline may not be tenable, as evidenced by these clinical trial results. The thought process behind Merck's approach was to combine three antiviral drugs with different modes of action to address the virus from different angles.
Though it makes sense in theory, it seems that with currently available drugs, treating HCV-infected patients for four weeks may allow them to attain "no detectable virus" status for a short period, but results in high levels of relapse and poor outcomes at the 12-weeks-post-treatment mark. That's the standard timeline for when a cure is considered definitive—or isn't.