Gilead Announces 100 Percent Sustained Virologic Response Rate (SVR4) for an Interferon-Free Regimen of Sofosbuvir (GS-7977), GS-5885 and Ribavirin in Treatment-Naïve Genotype 1 Hepatitis C Infected Patients

- Phase 3 Study with a Fixed-Dose Combination Tablet of Sofosbuvir and GS-5885 Now Underway -

BOSTON--(BUSINESS WIRE)--Nov. 10, 2012-- Gilead Sciences (Nasdaq: GILD) today announced interim data from the ongoing Phase 2 ELECTRON study examining a 12-week course of therapy with the investigational nucleotide sofosbuvir (formerly referred to as GS-7977), the NS5A inhibitor GS-5885 and ribavirin in patients with genotype 1 chronic hepatitis C virus (HCV) infection. Among treatment-naïve patients receiving this combination, 100 percent (n=25/25) remained HCV RNA undetectable four weeks after completing therapy (SVR4). These data will be presented on Tuesday, November 13^th at the 63rd annual meeting of the American Association for the Study of Liver Diseases (The Liver Meeting 2012) in Boston.

“These results indicate that adding GS-5885 to sofosbuvir-based regimens may enhance SVR rates, potentially offering HCV genotype 1 infected patients a convenient 12-week course of oral therapy,” said Professor Edward Gane, MD, Deputy Director and Hepatologist, New Zealand Liver Transplant Unit, Auckland City Hospital in New Zealand, and principal investigator of the ELECTRON study. “Along with other data from the ELECTRON study, these results add to the growing body of evidence supporting the potential for effective sofosbuvir-based all-oral regimens.”

Gilead recently initiated the first Phase 3 trial (ION-I) evaluating a fixed-dose combination of sofosbuvir and GS-5885 in treatment-naïve genotype 1 patients. This four-arm study is evaluating the fixed-dose combination with and without ribavirin for 12-and 24-week durations in 800 patients, 20 percent of whom have evidence of cirrhosis.

Data from five additional arms of the ELECTRON study examining sofosbuvir-based therapy in various patient populations also will be presented:

Preliminary data from a subset of an ongoing cohort in the ELECTRON study in which nine genotype 1 previous null responders were treated with sofosbuvir, GS-5885 and ribavirin for 12 weeks also will be presented on Tuesday. Thus far, three of the nine patients have reached the four-week post-treatment time point and all three remain HCV negative.

Both sofosbuvir in combination with ribavirin and sofosbuvir in combination with GS-5885 and ribavirin were well tolerated in the ELECTRON study. In the sofosbuvir combined with GS-5885 and ribavirin groups, there was one discontinuation due to an adverse event unrelated to study drugs. Despite stopping therapy at week 8, this patient also achieved SVR4.

The most common adverse events were headache, fatigue, upper respiratory tract infection and nausea. The most common clinically significant grade 3/4 laboratory abnormality was a hemoglobin reduction.

Additional Safety Data for GS-5885

In a poster presentation at The Liver Meeting on Sunday, November 11^th, investigators will report combined safety data for more than 1,000 patients who have received at least one dose of GS-5885, in combination with other HCV medicines, in six ongoing Phase 2 clinical trials. In this analysis, 616 patients received a 30 mg dose and 423 patients received the 90 mg dose of GS-5885, which is being assessed in Phase 3 research. More than 700 patients completed at least 12 weeks of treatment with GS-5885. Approximately 70 percent of patients were treatment-naïve and 70 percent had HCV genotype 1a infection.

Researchers concluded that GS-5885 is safe and well tolerated. No laboratory abnormalities or other safety signal of concern has been observed in the GS-5885 development program.

Sofosbuvir and GS-5885 are investigational products and their safety and efficacy have not yet been established.

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 weeks post-treatment will not be as favorable as the sustained virologic response rates reported in this press release, the possibility that results from the arm of the ELECTRON study evaluating the efficacy and safety of sofosbuvir, GS-5885 and ribavirin in genotype 1 previous null responder patients will not be favorable once four and 12 week post-treatment data from all nine patients are available and the possibility of unfavorable results from additional arms of the ELECTRON study and subsequent clinical trials involving sofosbuvir and GS-5885 with and without ribavirin. As a result, sofosbuvir and GS-5885 as single agents or as a fixed-dose combination may never be successfully commercialized. Further, 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. 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 Annual Report on Form 10-K 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.

For more information on Gilead Sciences, please visit the company’s website at www.gilead.com, follow Gilead on Twitter (@GileadSciences) or call Gilead Public Affairs at 1-800-GILEAD-5 or 1-650-574-3000.

Source: Gilead Sciences, Inc.

Gilead Sciences, Inc.Patrick O’Brien, 650-522-1936InvestorsorCara Miller, 650-522-1616Media