96-Week Data from Gilead's Study 934 Comparing Viread® and Emtriva® to Combivir® Both in Combination with Sustiva® Presented at XVI International AIDS Conference

Business Wire, August 14, 2006

TORONTO -- Gilead Sciences, Inc. (Nasdaq:GILD) today announced the presentation of 96-week data from an ongoing clinical trial (Study 934) comparing a once-daily regimen of Viread(R) (tenofovir disoproxil fumarate), Emtriva(R) (emtricitabine) and Sustiva(R) (efavirenz) to a twice-daily regimen of Combivir(R) (lamivudine/zidovudine) with Sustiva once daily in treatment-naive adults with HIV. Viread, Emtriva and Sustiva are available in the United States as the fixed-dose product ATRIPLA(TM) (efavirenz 600 mg/ emtricitabine 200 mg/ tenofovir disoproxil fumarate 300 mg), through a U.S. joint venture between Bristol-Myers Squibb and Gilead Sciences. ATRIPLA is currently approved in the United States for the treatment of HIV-1 infection in adults.

Study 934 is an ongoing Phase III, open-label clinical trial in the United States and Europe. Ninety-six week data are being presented by Joel Gallant, MD, Johns Hopkins University School of Medicine, Baltimore, at the XVI International AIDS Conference taking place August 13-18 in Toronto (Poster # TUPE0064). Data from this analysis have not been reviewed by the U.S. Food & Drug Administration.

"We now have two-year data suggesting that the once-daily regimen contained in Atripla is convenient and tolerable for many patients, and can provide effective, durable viral suppression over the long term," said Dr. Gallant. "Long-term studies like this one are important to demonstrate the durability of antiretroviral regimens, as patients are beginning to initiate treatment earlier and remain on treatment for longer periods of time."

Study 934

Study 934 is a Phase III, randomized, open-label, active-controlled, multicenter, non-inferiority study that enrolled 517 HIV-infected patients in the United States and Europe. The study's primary endpoint was at 48 weeks and the study is continuing through 144 weeks. The prespecified primary efficacy population included all patients who received at least one dose of study medication and who did not have NNRTI resistance at baseline (n=487). Participants in one arm of the study received Viread 300 mg, Emtriva 200 mg and Sustiva 600 mg, all dosed once daily. Patients in the comparator arm received Combivir twice daily and Sustiva 600 mg once daily. At study entry, patients had not previously received antiretroviral therapy and had HIV RNA (viral load) greater than 10,000 copies/mL.

After 96 weeks of treatment (n=463), 75 percent of patients in the Viread/Emtriva/Sustiva arm compared to 62 percent of patients in the Combivir/Sustiva arm achieved and maintained HIV RNA less than 400 copies/mL using the Time to Loss of Virologic Response algorithm (TLOVR) (p=0.004; 95% CI, 4% to 21%). Sixty-seven percent of patients in the Viread/Emtriva/Sustiva arm compared to 61 percent of patients in the Combivir/Sustiva arm achieved and maintained HIV RNA less than 50 copies/mL using the TLOVR algorithm (p=0.16; 95% CI, -2% to 15%). Patients receiving Viread/Emtriva/Sustiva experienced a greater mean increase from baseline in CD4 cell counts at week 96 compared to those receiving Combivir/Sustiva (270 vs. 237 cells/mm3; p=0.036).

Genotypic resistance analyses were performed on all patients from the primary efficacy population who either had confirmed plasma HIV RNA greater than 400 copies/mL or discontinued study drug early. Through 96 weeks, no patients in either arm of the study developed the K65R mutation, which is associated with reduced susceptibility to Viread. Fewer Viread/Emtriva/Sustiva patients developed the M184V/I mutation, which is associated with resistance to Emtriva and to the lamivudine component of Combivir (2 patients, vs. 9 in the Combivir/Sustiva arm; p=0.036).

After 96 weeks of treatment, a significantly greater percentage of patients in the Combivir/Sustiva group experienced adverse events that resulted in discontinuation of study medications compared to the Viread/Emtriva/Sustiva arm (11 vs. 5 percent, respectively; p=0.023). The most common cause of discontinuation related to study drug in the Combivir/Sustiva arm was anemia (14 patients, vs. 0 in the Viread/Emtriva/Sustiva arm; p less than 0.001), and in the Viread/Emtriva/Sustiva arm was rash, which occurred in 4 patients.

Renal safety was similar and renal function remained stable through 96 weeks in the two groups. No patient discontinued study medication due to renal events. Patients receiving Viread/Emtriva/Sustiva had a significantly greater median increase from baseline in weight compared to patients receiving Combivir/Sustiva (2.7 kg vs. 0.5 kg, respectively; p less than 0.001). In addition, in a subset of patients with 48- and 96-week data, a significant median decrease in limb fat was seen in the Combivir/Sustiva arm (decrease from 6.0 to 5.5 kg; n=44; p=0.001) while a significant median increase was observed in the Viread/Emtriva/Sustiva arm (increase from 7.4 to 8.1 kg; n=49; p=0.01).

Important Product Safety Information

Lactic acidosis and severe hepatomegaly with steatosis, including fatal cases, have been reported with the use of nucleoside analogues alone or in combination with other antiretrovirals.