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Abacavir/lamivudine (ABC/3TC) shows robust virologic responses in ART-naïve patients for baseline (BL) viral loads (VL) of ³100,000c/mL and <100,000c/mL by endpoint used in ACTG5202
Presented by Keith Pappa, United States.
K. Pappa1, J. Hernandez2, B. Ha1, M. Shaefer2, C. Brothers2, Q. Liao3
1GlaxoSmithKline, Infectious Diseases MDC, U.S. HIV Collaborative Studies, Research Triangle Park, NC, United States, 2GlaxoSmithKline, Infectious Diseases MDC, U.S. HIV, Research Triangle Park, NC, United States, 3GlaxoSmithKline, MDC BDS-Infectious Diseases, U.S., Research Triangle Park, NC, United States
Background: ACTG5202 is an ongoing randomized trial in 1858 ART-naïve pts evaluating open-label efavirenz (EFV) or ritonavir-boosted atazanavir (ATV/r) combined with ABC/3TC or tenofovir/emtricitabine (TDF/FTC). A recent review of ACTG5202 by the DSMB noted greater risk of virologic failure and adverse events in ABC/3TC-treated pts compared to TDF/FTC-treated pts with BL VL³100,000 c/mL. An analysis was performed of other clinical trials using ABC/3TC-containing regimens using the efficacy endpoint defined in ACTG5202 to assess impact of BL VL on virologic response.
Methods: 48-wk efficacy data in 2940 ART-naïve pts were analyzed by BL VL strata (<100,000 and ³100,000c/mL) from 6 clinical trials. The efficacy endpoint using Kaplan-Meier analysis was time to virologic failure (defined as confirmed VL ³1,000c/mL at or after 16 wks and before 24 wks, or VL ³200c/mL at or after 24 wks). The safety endpoint was defined as time to onset of first grade 3/4 sign, symptom, or lab toxicity at least 1 grade higher than BL. Tabled below are the Kaplan-Meier estimates of the probability of reaching the safety endpoint.
Results: By 48 wks, 87%-95% of subjects did not experience virologic failure. The safety endpoint outcome was similar in both strata.
Conclusions: Using the efficacy and safety endpoint defined in ACTG5202, this analysis of 6 clinical trials showed that the efficacy of ABC/3TC-containing regimens was robust in ART-naïve pts irrespective of BL VLs.