144-Week Data from Gilead's Study 934 Comparing Truvada® to Combivir® Both in Combination with Sustiva® Presented At International AIDS Society Meeting in Sydney

Business Wire, July 23, 2007

SYDNEY, Australia -- Gilead Sciences, Inc. (Nasdaq:GILD) today announced the presentation of 144-week data from an ongoing clinical trial, Study 934, comparing a once-daily regimen of Truvada([R]) (emtricitabine and tenofovir disoproxil fumarate) and Sustiva([R]) (efavirenz) to a twice-daily regimen of Combivir([R]) (lamivudine/zidovudine) with Sustiva once daily in treatment-naive adults with HIV. Data were presented by Jose Arribas, MD, of the University Hospital La Paz, Madrid, Spain at the 4th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention taking place July 22-25 in Sydney, Australia (Poster #WEPEB029).

Study 934 is an ongoing Phase III, open-label clinical trial in the United States and Europe. Truvada is a fixed-dose once-daily tablet containing Gilead's Viread([R]) (tenofovir disoproxil fumarate) and Emtriva([R]) (emtricitabine). At study initiation, patients received Viread and Emtriva with Sustiva. At week 96, which coincided with commercial availability of Truvada in the United States, all patients receiving Viread, Emtriva and Sustiva were switched to receive a simplified regimen of Truvada and Sustiva. Truvada is currently the most commonly prescribed nucleoside backbone for combination HIV therapy in the United States.

Truvada and Sustiva are also 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 Company and Gilead Sciences. Atripla was approved in the United States on July 12, 2006.

"These data demonstrate the safety and efficacy profile of the components of Atripla over three years," commented Dr. Arribas. "As the treatment landscape for HIV improves and patients live longer, the importance of a proven and durable first-line regimen with simple dosing is critical."

Study 934 Results

Study 934 is a Phase III, open-label, non-inferiority study that enrolled 517 HIV-infected patients in the United States and Europe. Two patients were protocol violations and six never received drug, resulting in an intent to treat population of 509 patients. The study's primary endpoint was at 48 weeks and the study has continued through 144 weeks. Twenty-two patients with baseline non-nucleoside reverse transcriptase inhibitor (NNRTI) mutations and 31 patients who completed week 48 and week 96 of the study with HIV RNA (viral load) less than 400 copies/mL but did not consent to participate after week 96 were excluded from the week 144 efficacy population. Participants were originally randomized to receive Viread 300 mg, Emtriva 200 mg and Sustiva 600 mg, all dosed once daily, or Combivir twice daily and Sustiva 600 mg once daily. At study entry, patients were treatment-naive, had HIV RNA greater than 10,000 copies/mL and any CD4 cell count. At week 96, patients receiving Viread, Emtriva and Sustiva were switched to a regimen of Truvada/Sustiva.

After 144 weeks of treatment, 71 percent of Truvada/Sustiva patients compared to 58 percent of Combivir/Sustiva patients achieved and maintained viral load less than 400 copies/mL using the Time to Loss of Virologic Response algorithm (TLOVR) (n=456, p=0.004; 95% CI, 4.2% to 21.6%). Sixty-four percent of patients in the Truvada/Sustiva arm compared to 56 percent of patients in the Combivir/Sustiva arm achieved and maintained viral load less than 50 copies/mL using TLOVR (n=458, p=0.08; 95% CI, -0.8% to 17%). The mean increase from baseline in CD4 cell counts at week 144 was 312 and 271 cells/mm3 in the Truvada/Sustiva and Combivir/Sustiva arms, respectively (p=0.09).

Genotypic resistance analyses were performed on patients without pre-existing baseline NNRTI resistance mutations who either had confirmed plasma HIV RNA greater than 400 copies/mL or discontinued study drug early. Through 144 weeks, no patients in either arm of the study developed the K65R mutation, which is associated with reduced susceptibility to Viread. Fewer Truvada/Sustiva patients developed the M184V/I mutation, which is associated with resistance to Emtriva and to the lamivudine component of Combivir (2 vs. 10 patients; p=0.02).

After 144 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 Truvada/Sustiva arm (11 vs. 5 percent, respectively; p=0.01). The most common cause of discontinuation in the Combivir/Sustiva arm was anemia/hemoglobin decrease (14 vs. 0 patients in the Truvada/Sustiva arm), and in the Truvada/Sustiva arm was rash (4 patients vs. 1 patient in the Combivir/Sustiva arm).

Renal adverse events were uncommon at 144 weeks, consistent with study data at weeks 48 and 96. No patient discontinued study medication due to renal events.

After 144 weeks of treatment, patients in the Combivir/Sustiva arm experienced greater mean elevations from baseline in fasting total cholesterol levels (36 vs. 24 mg/dL in the Truvada/Sustiva arm; p=0.005) and greater mean increases from baseline in fasting triglycerides (36 vs. 4 mg/dL in the Truvada/Sustiva arm; p=0.047).