Hard-to-Cure Patients May Benefit from Merck's HCV Drug

Merck (MRK) presented interim data from an ongoing phase II study on its once-daily, all-oral hepatitis C virus (:HCV) combination regimen – MK-5172 (a NS3/4A protease inhibitor) and MK-8742 (a NS5A replication complex inhibitor). The additional data was presented at the annual meeting of the European Association for the Study of the Liver (:EASL).

The randomized, dose-responsive, parallel-group, multiple-site, double-blind, phase II C-WORTHy study is evaluating the efficacy and safety of MK-5172/MK-8742 in patients with chronic HCV genotype 1 infection (GT1). Interim analysis revealed that impressive sustained virologic response rates (:SVR) were observed for 12 or 18 weeks after 4 to 8 weeks of completion of therapy in hard-to-cure patients. Hard-to-cure patients include first-line patients with liver cirrhosis, prior-null responder patients with and without cirrhosis and patients with HIV/HCV co-infection.

The study assessed MK-5172 plus MK-8742 in different patient populations for different treatment durations with or without ribavirin (RB.V). SVR rates for 12 and 18 weeks in treatment-naïve cirrhotic patients were 97% (both) in the MK-5172/MK-8742 arm as compared to 90% and 97%, respectively, in patients who received MK-5172/MK-8742 plus RBV.

SVR rates for 12 and 18 weeks in prior-null responder patients were higher in MK-5172/MK-8742 plus RBV arm (94% and 100%, respectively) as compared to the MK-5172/MK-8742 arm (91% and 97%, respectively). 12-weeks SVR rate in treatment-naïve, non-cirrhotic patients with HCV/HIV co-infection treated with MK-5172/MK-8742 was 90% and MK-5172/MK-8742 plus RBV was 97%.

Based on encouraging data from phase II studies, Merck has initiated a phase III program, C-EDGE, which will evaluate the safety and efficacy of MK-5172/MK-8742 with and without RBV in several genotypes and a range of patient populations with chronic HCV.

Our Take

We are pleased with the string of positive data presented by Merck on its investigational HCV therapy. We believe that it has a good chance of gaining approval based on high response rates. A new successful HCV treatment would provide a boost to Merck’s sales. We note that Merck’s HCV drug, Victrelis, recorded revenues of $428 million (down 15%) in 2013.

Several companies are working on getting their all-oral treatment regimens for HCV patients with GT1 in the market. Gilead Sciences Inc. (GILD) is looking to get its once-daily fixed-dose HCV cocktail treatment, ledipasvir plus Sovaldi, approved in the U.S. The company has already submitted a marketing application to the FDA. Meanwhile, Bristol-Myers Squibb Company (BMY) is not far behind. A few days back, the company submitted a marketing application for its all-oral combination of daclatasvir and asunaprevir. The FDA has granted Breakthrough Therapy designation to the combination. AbbVie Inc. (ABBV) is also developing an oral investigational fixed-dose combination regimen (phase III) targeting this lucrative market. We believe that apart from efficacy and safety, dosing and pricing will play crucial roles in determining the winner.

Merck currently carries a Zacks Rank #3 (Hold). Bristol-Myers is a better-ranked stock with a Zacks Rank #2 (Buy).

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