Gilead Sciences Inc. announced that the company's Marketing Authorisation Application (MAA) for sofosbuvir, a once-daily oral nucleotide analogue inhibitor for the treatment of chronic hepatitis C virus (HCV) infection, which was submitted to the European Medicines Agency (EMA) on April 17, 2013, has been fully validated and is now under assessment. The data submitted in this MAA support the use of sofosbuvir and ribavirin (RBV) as an all-oral therapy for patients with genotype 2 and 3 HCV infection, and for sofosbuvir in combination with RBV and pegylated interferon (peg-IFN) for treatment-naïve patients with genotype 1, 4, 5 and 6 HCV infection. The MAA for sofosbuvir is supported primarily by data from four Phase 3 studies, NEUTRINO, FISSION, POSITRON and FUSION, in which 12 or 16 weeks of sofosbuvir-based therapy was found to be superior or non-inferior to currently available treatment options or historical controls, based on the proportion of patients who had a sustained virologic response (HCV undetectable) 12 weeks after completing therapy (SVR12).

Gilead Sciences Inc. announced results from a Phase 2 study (Study 101-08) evaluating idelalisib (formerly GS-1101), an investigational, targeted, oral inhibitor of PI3K delta, in combination with rituximab for older patients with treatment-naïve chronic lymphocytic leukemia (CLL). This regimen achieved a complete response (CR) rate of 19% and an overall response rate (ORR) of 97%, with estimated progression-free survival (PFS) at 24 months of 93%. CLL is a slow-growing cancer that induces the production of too many mature white blood cells. It is the second most common type of leukemia in the United States and can lead to life-threatening complications, including serious infection. Currently, patients with CLL are usually treated first with rituximab in combination with one or more chemotherapy agents. Among the 64 patients in the study, Kaplan-Meier estimated PFS at 24 months was 93%. The median time on treatment was 14 months, with 33 patients remaining on treatment. The median time to response was two months. No relapses on study have been reported. The nine patients with chromosome 17p deletion (del 17p) (n=6) or mutation in the TP53 gene (n=3), which have been linked to poor prognosis, all responded to therapy including three with a complete response. Ninety-four percent of patients with thrombocytopenia at baseline responded to treatment (16/17), as did all patients with anemia at baseline (17/17). Of patients with systemic symptoms such as extreme fatigue, fever, night sweats or weight loss (known as "B symptoms") at baseline, 77% (20/26) were asymptomatic by eight weeks. Patients completing 48 weeks of therapy without progression could continue to receive idelalisib in an extension study. Forty-three patients completed 48 weeks of treatment (21 discontinued -- 17 due to adverse events, three due to death and one due to other reasons); 40 patients entered the extension study and 33 remain on treatment. During the primary and extension study, Grade 3 diarrhea and/or colitis was reported in 33% of patients, Grade >=3 pneumonia in 17% and Grade >=3 transaminase elevations (measure of liver function) in 23 percent of patients.

On January 30, 2013, Gilead Sciences Inc. Board adopted an amendment to the company's Restated Certificate of Incorporation to increase the authorized number of shares of the company's common stock from 2,800,000,000 shares to 5,600,000,000 shares. At the annual meeting of the company held on may 8, 2013, the company's stockholders approved an amendment to its restated certificate of incorporation.