1. Lack of Pharmacokinetic Interaction Between Ritonavir-Boosted GS-9137 (Elvitegravir) and Tipranavir/r Anita A. Mathias 1, John Hinkle 1, Jeff Enejosa 1, Peter J. Piliero 2, and Brian P. Kearney 1 Anita A. Mathias 1, John Hinkle 1, Jeff Enejosa 1, Peter J. Piliero 2, and Brian P. Kearney 1 1 Gilead Sciences, Foster City, CA; 2 Boehringer Ingelheim Pharmaceuticals, Inc, Ridgefield, CT 4th International AIDS Conference (IAS) July 22-25, 2007 Sydney, Australia

2. Results Open-label, multiple dose, three treatment, six sequence crossover study % GMR (90% CI) (n = 26) PK ParameterEVGTPVRTV (TPV/r vs. EVG+TPV/r) AUC tau 92.4 (78.7, 108)88.9 (80.0, 98.8)99.1 (86.3, 114) C max 106 (89.4, 126)91.6 (83.8,100)106 (88.2, 126) C tau 90.4 (69.8, 117)88.9 (77.4, 102)110 (91.7, 133) TPV C tau of 6050 ng/mL = 5-fold greater than protein-binding adjusted IC 90 for multiple PI resistant HIV-1 (King JR and Acosta EP, Clin. Pharmacokinet; 2006; 45(7):665-682) C tau consistent with historical controls (US Prescribing Information) Safety No deaths, or SAE were reported in this study No subject discontinued for an AE during treatment of EVG/r alone; 4 subjects discontinued for AE (G1/2 LFT elevations or rash) while receiving TPV/r

3. Conclusions The steady-state pharmacokinetics of EVG or TPV were not altered following coadministration of EVG with ritonavir-boosted TPV; including maintenance of trough concentrations EVG can be coadministered with TPV/r without any dose adjustment Treatment with EVG/r alone was generally well tolerated. Treatment with TPV/r alone or in combination with EVG was associated with an increased incidence of treatment-emergent and -related adverse events