Four ongoing Phase 3 studies will support Gilead’s initial regulatory filing in mid-2013 for an all-oral therapy with sofosbuvir plus RBV among genotype 2/3 treatment-naïve, treatment-experienced and interferon-intolerant patients, and for sofosbuvir in combination with RBV and peg-IFN among treatment-naïve patients with HCV genotypes 1, 4, 5 and 6. Topline results from the first Phase 3 study, POSITRON, were announced in November 2012, and results from the remaining three studies (FISSION, FUSION and NEUTRINO) are anticipated in Q1 2013. Results from ION-1, ION-2 and LONESTAR are intended to support a regulatory filing for the fixed-dose combination of sofosbuvir/GS-5885 by mid-2014.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. Forward-Looking Statement This press release includes forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 that are subject to risks, uncertainties and other factors, including the possibility that the proportion of patients who maintain a sustained virologic response 12 and 24 weeks post-treatment in the null responder arm of the ELECTRON study will not be as favorable as the sustained virologic response rates reported in this press release, and the possibility of unfavorable results from additional arms of ELECTRON and other clinical trials involving sofosbuvir and sofosbuvir and GS-5885 with and without RBV. As a result, sofosbuvir and GS-5885 as single agents or as a fixed-dose combination may never be successfully commercialized. In addition, Gilead may make a strategic decision to discontinue development of the compounds or the fixed-dose combination regimen if, for example, Gilead believes commercialization will be difficult relative to other opportunities in its pipeline. Further, Gilead may be unable to file for regulatory approval of sofosbuvir and the fixed-dose combination of sofosbuvir/GS-5885 in the currently anticipated timelines or at all. If marketing approval is granted for any of these products, there may be significant limitations on their use. These risks, uncertainties and other factors could cause actual results to differ materially from those referred to in the forward-looking statements. The reader is cautioned not to rely on these forward-looking statements. These and other risks are described in detail in Gilead’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2012, as filed with the U.S. Securities and Exchange Commission. All forward-looking statements are based on information currently available to Gilead, and Gilead assumes no obligation to update any such forward-looking statements.