1. Copyright ©2011 Merck & Co., Inc., Whitehouse Station, New Jersey, USA, All Rights Reserved IAS 2011_ Abstract # WEPDB0102 Sustained Efficacy and Tolerability of Raltegravir after 240 Weeks of Combination ART in Treatment-Naive HIV-1 Infected Patients: Final Analysis of Protocol 004 E. Gotuzzo 1, B.-Y. Nguyen 2, M. Markowitz 3, F. Mendo 4, W. Ratanasuwan 5, C. Lu 2, S. Bhanja 2, H. Teppler 2, and the Protocol 004 Part II Study Team 1 Hospital Nacional Cayetano Heredia, Lima, Peru; 2 Merck Research Labs, North Wales, PA, United States; 3 Aaron Diamond AIDS Research Center, New York, NY, United States; 4 Hospital Nacional Edgardo Rebagliati, Lima, Peru; 5 Siriraj Hospital, Bangkok, Thailand

2. Copyright ©2011 Merck & Co., Inc., Whitehouse Station, New Jersey, USA, All Rights Reserved IAS 2011_ Abstract # WEPDB0102 Percentage of Patients with HIV RNA < 50 copies/mL (NC=F) Change from Baseline in CD4 Cell Counts (OF) Virologic and Immunologic Responses 301.7 275.6 63.2% 68.8% Week 240 (OF approach): RAL 89% EFV 77% Raltegravir

3. Copyright ©2011 Merck & Co., Inc., Whitehouse Station, New Jersey, USA, All Rights Reserved IAS 2011_ Abstract # WEPDB0102 Safety Summary: Week 240 Overall adverse event (AE) profiles, all causality –Generally similar for RAL and EFV (other than neuropsychiatric AEs) –Similar frequencies reported at Weeks 192 and 240 Drug-related clinical AEs –Less common with RAL than EFV: 55% vs 76% (p=0.017) Neuropsychiatric symptoms* –Most occurred by Week 48 –At Week 240: 38% for RAL vs 63% for EFV Malignancies † –3.1% (5/160 pts) in RAL group, none considered drug-related –2.6% (1/38 pts) in EFV group, 1 event (GI carcinoma) possibly drug-related Grade 3 / 4 lab abnormalities uncommon –Similar frequencies reported at Weeks 192 and 240 Minimal effect of RAL on serum lipids *Abnormal dreams, adjustment disorder with depressed mood, depressed mood, depression, dizziness, insomnia, nightmare, psychotic disorder, somnolence, suicidal ideation, suicide attempt. † Cases included: in RAL group: 1 pt with B-cell lymphoma, 2 pts with Kaposi’s sarcoma, 1 pt with basal cell carcinoma and squamous cell carcinoma (SC), and 1 pt with non-small cell lung carcinoma; in EFV group: 1 pt with gastrointestinal carcinoma (possibly drug-related) and SC.

4. Copyright ©2011 Merck & Co., Inc., Whitehouse Station, New Jersey, USA, All Rights Reserved IAS 2011_ Abstract # WEPDB0102 Exploratory Analysis: Prognostic Factors Associated With CD4 Cell Count at Yearly Time Points Prognostic Factor P-value † Wk 48Wk 96Wk 144Wk 192Wk 240 Baseline CD4 cell count (cells/mm 3 ) <0.0001 Week 8 HIV RNA decline (log 10 copies/mL) 0.0005<0.0001 Treatment Group0.28870.35920.97780.6421 0.6057 † p-Value calculated from a linear regression model with CD4 cell count separately at each time point as the dependent variable adjusted for baseline CD4 cell count (c/mm 3 ), Week 8 HIV RNA decline (log 10 copies/mL) and treatment group. Significant predictors for CD4 cell count (at 0.05 critical value) at each time point were: (1) baseline CD4 count and (2) log HIV RNA decline at week 8.

5. Copyright ©2011 Merck & Co., Inc., Whitehouse Station, New Jersey, USA, All Rights Reserved IAS 2011_ Abstract # WEPDB0102 CONCLUSIONS RAL + TDF/3TC demonstrated sustained antiretroviral efficacy through 5 years, similar to EFV + TDF/3TC: –HIV RNA <50 copies/mL in 69% of RAL patients vs 63% of EFV patients –CD4 counts continued to increase through 5 years in both groups RAL was generally well tolerated over 5 years: –Safety profile similar to Week 144 (3 years) and Week 192 (4 years) –Drug-related AEs less frequent with RAL than EFV –RAL has minimal effect on LDL-cholesterol and triglycerides In an exploratory analysis, statistically significant predictors for CD4 cell count at each yearly time point were baseline CD4 count and early (week 8) log HIV RNA decline.