Gilead's Second Phase 3 Clinical Study of the Investigational Antiretroviral Quad Regimen Meets 48-Week Primary Objective

Gilead's Second Pivotal Phase 3 Clinical Study of the Investigational Antiretroviral Quad Regimen Meets 48-Week Primary Objective

- Company to Host Conference Call at 4:30 p.m. Eastern Time Today -

FOSTER CITY, Calif., Sep 19, 2011 (BUSINESS WIRE) --

Gilead Sciences, Inc. (Nasdaq: GILD) today announced that the second pivotal Phase 3 clinical trial (Study 103) of its investigational fixed-dose, single-tablet "Quad" regimen of elvitegravir, cobicistat, emtricitabine and tenofovir disoproxil fumarate, being evaluated for HIV-1 infection in treatment-naïve patients, met its primary objective of non-inferiority at week 48 as compared to ritonavir-boosted atazanavir plus Truvada(R) (emtricitabine/tenofovir disoproxil fumarate) based on the proportion of subjects who achieved HIV RNA levels (viral load) of less than 50 copies/mL.

The primary endpoint analysis indicated that 90 percent of patients in the Quad arm compared to 87 percent in the ritonavir-boosted atazanavir plus Truvada arm (95 percent CI for the difference: -1.9 percent to 7.8 percent) achieved HIV RNA of less than 50 copies/mL through week 48. The predefined criterion for non-inferiority was a lower bound of a two sided 95 percent CI of -12 percent. The discontinuation rate due to adverse events was higher in the ritonavir-boosted atazanavir arm (5.1 percent) as compared to the Quad (3.1 percent). This difference was driven primarily by elevated bilirubin levels observed in the ritonavir-boosted atazanavir arm. Other adverse events and laboratory abnormalities were similar between the two arms. Gilead plans to submit these data for presentation at a scientific conference early next year.

"The 90 percent response rate observed on the Quad arm in this study is an unprecedented result and speaks to the potency, safety and convenience of an integrase-based single-tablet regimen," said Norbert Bischofberger, PhD, Executive Vice President, Research and Development and Chief Scientific Officer, Gilead Sciences. "Based on the availability of data from both pivotal Studies 102 and 103, we are now working toward filing for U.S. regulatory approval of the Quad by the end of the year."

Conference Call

At 4:30 p.m. Eastern Time today, Gilead's management will host a conference call and a simultaneous webcast to discuss results from this study. To access the webcast live via the internet, please connect to the company's website at 15 minutes prior to the conference call to ensure adequate time for any software download that may be needed to hear the webcast. Alternatively, please call 1-866-730-5770 (U.S.) or 1-857-350-1594 (international) and dial the participant passcode 86019231 to access the call.

A replay of the webcast will be archived on the company's website for one year, and a phone replay will be available approximately two hours following the call through September 21, 2011. To access the phone replay, please call 1-888-286-8010 (U.S.) or 1-617-801-6888 (international) and dial the participant passcode 88891133.

About Study 103

Study 103 is a randomized, double-blind clinical trial comparing the efficacy, safety and tolerability of the Quad versus ritonavir-boosted atazanavir plus Truvadaover a 96-week period at more than 200 study sites in North America, South America, Europe and Asia Pacific. Eligible participants are HIV-infected treatment-naïve adults with HIV RNA levels greater than or equal to 5,000 copies/mL. Trial participants were randomized (1:1) to receive a once-daily tablet containing elvitegravir 150 mg/cobicistat 150 mg/emtricitabine 200 mg/tenofovir disoproxil fumarate 300 mg (n=353) or ritonavir 100 mg and atazanavir 300 mg plus Truvada (emtricitabine/tenofovir disoproxil fumarate) (n=355).

The primary endpoint of the study is the proportion of patients achieving HIV RNA levels of less than 50 copies/mL at 48 weeks of treatment. Secondary objectives will evaluate the efficacy, safety and tolerability of the treatment regimens through 96 weeks of treatment.

The study is ongoing in a blinded fashion. After week 96, subjects will continue to take their blinded study drug until treatment assignments have been unblinded, at which point all subjects will be given the option to participate in an open-label rollover extension and receive the Quad single-tablet regimen. Additional information about the study can be found at

The Quad, elvitegravir and cobicistat are investigational products and have not yet been determined safe or efficacious in humans.

About the Quad

The Quad contains four Gilead compounds in a complete once-daily, single-tablet regimen: elvitegravir, an investigational integrase inhibitor; cobicistat, an investigational pharmacoenhancing or "boosting" agent that increases blood levels of certain HIV medicines; and Truvada. The Phase 3 clinical program for the Quad includes two studies (Studies 102 and 103) which are evaluating the Quad regimen versus a standard of care among HIV-1 infected antiretroviral treatment-naïve adults. Study 102, a randomized, double-blind clinical trial comparing the efficacy, safety and tolerability of the Quad versus Atripla(R) (efavirenz 600 mg/emtricitabine 200 mg/tenofovir disoproxil fumarate 300 mg) is ongoing, and the company announced that the study met its primary objective of non-inferiority at week 48 on August 15, 2011.

About Elvitegravir

Elvitegravir is an HIV integrase inhibitor. Unlike other classes of antiretroviral agents, integrase inhibitors interfere with HIV replication by blocking the ability of the virus to integrate into the genetic material of human cells. Elvitegravir was licensed by Gilead from Japan Tobacco Inc. (JT) in March 2005. Under the terms of Gilead's agreement with JT, Gilead has exclusive rights to develop and commercialize elvitegravir in all countries of the world, excluding Japan, where JT retains rights.

About Cobicistat

Cobicistat is Gilead's proprietary potent mechanism-based inhibitor of cytochrome P450 3A (CYP3A), an enzyme that metabolizes drugs in the body. In addition to studying the agent as part of an integrase-based fixed-dose regimen, Gilead is also examining cobicistat's potential stand-alone role in boosting commercially available HIV protease inhibitors, which are used in many HIV treatment regimens.

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.