Various updates have been announced pertaining to Gilead Sciences’ late-stage, forthcoming candidates for the treatment of chronic hepatitis C infection (HCV).

The company made public results of an ongoing Phase 2 ELECTRON study analyzing the nucleotide sofosbuvir and the NS5A inhibitor GS-5885, as well as giving a progress report on several Phase 2 and 3 clinical trials assessing a once a day daily, fixed dose pill mixture containing both medicines.

Outcomes from eight other parts of the ELECTRON study were published earlier this month.

Norbert Bischofberger, PhD, Executive Vice President, Research and Development and Chief Scientific Officer, Gilead Sciences, said:

“Since the acquisition of Pharmasset only a year ago, we have fully enrolled four Phase 3 studies of sofosbuvir and during the first quarter of this year we will have initiated two Phase 3 studies of the sofosbuvir and GS-5885 fixed-dose combination. We are on track to submit the initial regulatory filing for sofosbuvir by mid-2013 and to file for approval of the fixed-dose combination of sofosbuvir and GS-5885 in 2014.”


The results came from a 12 week course of oral treatment with softosbuvir, GS-5885 and ribavirin (RBV) with patients with genotype 1 HCV who have not showed any progress from interferon therapy.

Data presented in November showed that three out of nine participants stayed HCV RNA undetectable four weeks following treatment (SVR4). The most recent announcement verifies that all nine patients in this particular group reached SVR4. The patients will continue to be followed to monitor sustained virologic response rates at 12 and 24 weeks (SVR12 and SVR24).

ION-1: A Phase 3 trial that started in October of 2012 and is measuring sofosbuvir/GS-5885 with and without RBV for 12 or 24 weeks. After an analysis of results from the two 12 week parts of an enrollment of 200 patients, ION-1 will recruit more participants and examine sofosbuvir/GS-5885 in 800 people.

ION-2: The 2nd Phase 3 trial for sofosbuvir/GS-5885 is planning on starting to screen patients this month. The study will analyze the fixed-dose combination with RBV for 12 weeks and with and without RBV for 24 weeks of treatment for patients with genotype 1 HCV. Individuals in this study will have not responded to earlier treatment with IFN or IFN with a protease inhibitor.

LONESTAR: Enrollment is taking place for another Phase 2 study of sofosbuvir/GS-5885 for 12 weeks and of sofosbuvir/GS-5885 with and without RBV for 8 weeks, for patients with genotype 1 HCV who have not responded to previous treatment. There will be two more parts to this trial that will assess sofosbuvir/GS-5885 with and without RBV for 12 weeks for patients with genotype 1 HCV who had previously had a protease inhibitor-containing regimen. This is the first study to assess the combination of sofosbuvir and GS-5885 for just an 8 week time period for treatment.

Sofosbuvir and GS-5885, as well as the fixed-dose combination, are new exploratory products and their safety and effectiveness have not been proven as of yet.

Written by Kelly Fitzgerald