Merck Announces Presentation of Interim Data from Study of Investigational Combination of HCV Therapies MK-5172 and MK-8742 at the 2013 American Association for the Study of Liver Diseases (AASLD) Annual Meeting

WHITEHOUSE STATION, N.J.--(BUSINESS WIRE)--Merck (NYSE: MRK), known as MSD outside of the United States and Canada, announced the presentation of interim data from the ongoing C-WORTHY Study, a Phase II clinical trial evaluating the efficacy and safety of an all-oral regimen combining once-daily MK-5172, an investigational hepatitis C virus (HCV) NS3/4A protease inhibitor, and MK-8742, an investigational HCV NS5A replication complex inhibitor, with or without twice-daily ribavirin, administered for 12 weeks to treatment-naïve, non-cirrhotic patients with HCV genotype 1a and 1b infection. The interim data show that the administration of MK-5172 and MK-8742 in combination is associated with a sustained virologic response (lack of detectable and quantifiable HCV) 12 weeks following the end of study therapy (SVR12). Merck previously announced that the U.S. Food and Drug Administration (FDA) granted Breakthrough Therapy designation to MK-5172/MK-8742 for treatment of chronic HCV infection.

"We are encouraged by these preliminary data for the combination of MK-5172 and MK-8742," said, Dr. Eliav Barr, vice president, Infectious Diseases, Merck Research Laboratories. "These data provide further support that we can advance these candidates, which are currently in Phase IIB clinical development, into a broader evaluation in a diverse range of HCV patients."


In the C-WORTHY Study, 65 patients (45% male, 11% African American, and 58% genotype 1a infection) were enrolled in one of three 12-week treatment arms (see TABLE). The ribavirin (RBV) arms were stratified by genotype 1a versus genotype 1b. The RBV-free arm included only genotype 1b-infected patients. Virologic response was assessed each week during treatment and at 2, 4, 8, 12 and 24 weeks after the end of treatment. The primary efficacy endpoint of the trial was the proportion of patients who achieved sustained virologic response at post-treatment follow-up week 12 (SVR12).

The primary analysis population was per protocol, including patients who did not have protocol violations and had received the correct study medications. A total of 58/65 enrolled patients met these criteria (see TABLE).

Of the seven patients who were not in the per-protocol population, four achieved SVR12 and three discontinued early for reasons other than adverse experiences or virologic failure.

Among the entire study population of 65 patients, one patient (1.5%) experienced a relapse with detectable HCV RNA at follow-up week 4 and 12.


Primary Analysis Population: Per Protocol*

Arm Regimen N GT1a / GT1b SVR4 SVR12#
1 MK-5172 (100 mg) + MK-8742 (20 mg) + ribavirin 22 76% / 24% 22/22




2 MK-5172 (100 mg) + MK-8742 (50 mg) + ribavirin 24 70% / 30% 23/24




3 MK-5172 (100 mg) + MK-8742 (50 mg) 12 0% / 100%




* Seven Patients were excluded from the Per Protocol Population


  • 4 patients received incorrect RBV doses (3 received <50% of the prescribed dose:1 given RBV in the RBV-free arm); all achieved HCV-RNA <25 IU/mL at FU12
  • 3 patients discontinued early:1 patient at Day 3 (violated protocol inclusion criterion), and 2 patients at Day 22 and Day 35 (withdrew consent – patients had undetectable HCV RNA at the time of discontinuation)

#Two patients have not reached SVR12

The most frequently reported adverse events occurring in the study were fatigue (26%), headache (22%), nausea (18%), diarrhea (12%), dizziness (11%) and rash (11%). The incidence of anemia (<10 mg/dL hemoglobin) and elevated total bilirubin levels to 2 times the upper limit of normal was 19 percent and 4 percent, respectively, in the RBV-containing arms (combined arms 1 and 2), and 0 percent and 0 percent, respectively, in the RBV-free arm. No grade 3 or 4 laboratory abnormalities were observed. There were eight cases of rash. Seven cases of rash were observed in the RBV-containing arms; half of these cases were attributed to RBV. The single case in the RBV-free arm was not study drug related and was mild in intensity. No early discontinuations due to drug-related adverse events were recorded.

The C-WORTHY trial has been expanded to evaluate the safety and efficacy of MK-5172 and MK-8742, with or without RBV, in difficult-to-cure HCV genotype 1-infected patient populations. Approximately 400 additional HCV genotype 1-infected patients have been enrolled in this trial. The expanded C-WORTHY study is testing:

  • 8 week regimen of MK-5172/MK-8742 + RBV in treatment naïve non-cirrhotic patients
  • 12 week regimen of MK-5172/MK-8742 without RBV in treatment-naïve non-cirrhotic patients
  • 12 week regimens (MK-5172/MK-8742 with or without RBV) among HIV co-infected patients
  • 12 or 18 week regimens (MK-5172/MK-8742 with or without RBV) in patients with cirrhosis
  • 12 or 18 week regimens (MK-5172/MK-8742 with or without RBV) in patients who had failed to respond to prior peginterferon and RBV therapy ("null responders").

Details on the C-WORTHY Study, as well as additional phase II trials for MK-5172 and MK-8742, can be viewed on

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