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Hard-to-Treat Hepatitis C Patients Relapse after Stopping Interferon-Free GS-7977/Ribavirin Regimen


A majority of prior null responders with difficult-to-treat hepatitis C virus (HCV) genotype 1 experienced viral rebound after completing treatment with an all-oral regimen of the HCV nucleotide polymerase inhibitor GS-7977 plus ribavirin.

Direct-acting antiviral agents (DAAs) have ushered in a new era of hepatitis C treatment, and researchers are hard at work to develop oral DAA combinations that can produce a cure without interferon and its notorious side effects.

One promising agent, GS-7977, has demonstrated promising results in early studies. Formerly known as PSI-7977, the drug was renamed when Gilead Sciences acquired Pharmasset late last year.

As reported at the American Association for the Study of Liver Diseases meeting (AASLD 2011) this past November, 100% of previously untreated patients with easier-to-treat HCV genotypes 2 or 3 achieved sustained virological response -- generally considered a cure -- with 12 weeks of GS-7977 plus ribavirin.

Another study found that about 90% of treatment-naive people with HCV genotype 1 achieved a cure with PSI-7977 plus pegylated interferon and ribavirin for 12 weeks, followed by pegylated interferon/ribavirin alone for another 12 weeks.

Last week, however, Gilead announced new data showing that the short, all-oral regimen is not effective for the more challenging population of genotype 1 prior null responders -- those who showed little or no response to previous interferon-based therapy.

In the ongoing ELECTRON trial, 6 out of 10 hard-to-treat patients using GS-7977 plus ribavirin without interferon experienced viral relapse within 4 weeks after finishing the 12-week course of treatment; 2 of the 10 patients in this study arm have not yet relapsed but are still undergoing evaluation, and 2 others do not yet have sufficient data.

Gilead indicated that clinical trials are continuing to test GS-7977 in other patient subgroups, and the company also plans to study it in combination with other DAAs.

Below is an edited excerpt from Gilead's press release describing the study and its latest findings.

Gilead Announces Data for Genotype 1 Null Responder Hepatitis C Patients Enrolled in ELECTRON Study

Viral Relapse Seen Post Treatment with GS-7977 Plus Ribavirin

Awaiting Data for Treatment-Naive Genotype 1 Patients

Foster City, Calif. -- February 17, 2012 -- Gilead Sciences, Inc. (NASDAQ:GILD) announced today that the majority of hepatitis C genotype 1 patients with a prior "null" response to an interferon (IFN)-containing regimen enrolled in the ongoing ELECTRON study experienced viral relapse within four weeks of completing 12 weeks of treatment with GS-7977 plus ribavirin (RBV). Ten patients were randomized to this arm of the ELECTRON study and data are available for eight of the 10 patients at this time. Among these eight patients, six have experienced viral relapse. Two patients have not relapsed; however, they have only reached the two week post-treatment time point.

"These data answer an important question about the use of GS-7977 and ribavirin for the treatment of genotype 1 null responder patients, suggesting that additional direct acting antivirals may be necessary to effectively treat this patient population," said Norbert Bischofberger, PhD, Executive Vice President of Research and Development and Chief Scientific Officer. "We will continue to explore a number of therapeutic approaches to address this significant unmet medical need, including combinations with other oral antivirals."

GS-7977 is a nucleotide analog polymerase inhibitor that is currently being studied for the treatment of chronic hepatitis C. A number of ongoing Phase 2 and Phase 3 studies are evaluating the safety and efficacy of the compound with and without RBV and/or pegylated interferon (Peg-IFN) in patients with genotypes 1-6 who are treatment naive, treatment experienced, or have had a "null" response to Peg-IFN.

Genotype 2 and 3 data from the ELECTRON study were presented at the 62nd annual meeting of the American Association for the Study of Liver Diseases (The Liver Meeting 2011). Data from the genotype 1 null responder arm of the study will be presented at an upcoming scientific conference.

Results from ongoing studies in genotype 1 treatment-naive patients will be available in the coming months. The first data evaluating GS-7977 plus RBV for 12 weeks in genotype 1 naive patients will come from an arm of the QUANTUM study with 25 patients at the end of the first quarter of 2012. This will be followed in the second quarter by data from the ELECTRON study involving 25 patients and, early in the third quarter, data on GS-7977 and RBV treatment for 24 weeks from an arm of the QUANTUM study will become available.

About Gilead Sciences

Gilead Sciences is a biopharmaceutical company that discovers, develops and commercializes innovative therapeutics in areas of unmet medical need. The company’s mission is to advance the care of patients suffering from life-threatening diseases worldwide. Headquartered in Foster City, California, Gilead has operations in North America, Europe and Asia Pacific. For more information on Gilead Sciences, please visit the company’s website at or call Gilead Public Affairs at 1-800-GILEAD-5 or 1-650-574-3000.



Gilead Sciences. Gilead Announces Data for Genotype 1 Null Responder Hepatitis C Patients Enrolled in ELECTRON Study. Press release. February 17, 2012.