Oral combination therapy for HCV delivers 85% SVR4

An all-oral, direct-acting antiviral combination therapy of samatasvir and simeprevir plus ribavirin resulted in up to 85% of patients achieving sustained virologic response at 4 weeks after completing the 12-week regimen, a company news release said.

The parallel-group phase 2 HELIX-1 clinical trial is designed to evaluate the antiviral activity, safety and tolerability of a weight-based dose of ribavirin along with samatasvir, a pan-genotypic NS5A inhibitor from Idenix Pharmaceuticals, and 150 mg simeprevir, a once-daily protease inhibitor developed by Janssen and Medivir, the release said.

In part A of the trial, 63 treatment-naive, noncirrhotic, genotype 1b or genotype 4 HCV-infected patients were randomly assigned therapy with either 50 mg, 100 mg or 150 mg samatasvir, the release said. Among the 20 patients assigned 50 mg samatasvir, 17 (85%) demonstrated SVR4. Among 21 patients receiving 100 mg samatasvir, SVR was demonstrated by 16 (76%). And among 150-mg patients, 10 of 19 (53%) achieved SVR4, while three patients prematurely discontinued treatment.

In part B, additional exploratory cohorts were added to analyze the impact of 25 mg samatasvir in conjunction with simeprevir and ribavirin on genotype 1b patients and the impact of 100 mg samatasvir in genotype 6 patients. No treatment-related serious adverse events were reported. Full results of the HELIX-1 trial are expected to be presented at a scientific meeting this year, the release said.

The HELIX-2 trial, a phase 2 study analyzing samatasvir, simeprevir and TMC647055, a once-daily non-nucleoside polymerase inhibitor boosted with low-dose ritonavir being developed by Janssen, is under way. It will evaluate safety and efficacy with and without ribavirin among genotype 1 treatment-naive patients and those who have relapsed after interferon and ribavirin therapy.

“We also have successfully completed the single-dose portion of the phase 1/2 clinical trial of IDX21437, a next-generation uridine nucleotide prodrug inhibitor, and the 7-day proof-of-concept portion of the study is under way,” Ron Renaud, president and CEO of Idenix, said in the release. “Based on these important developments, we are on track to initiate an Idenix-sponsored combination study of samatasvir and IDX21437 by mid-2014.”