Why We Do the Things We Do: ACTG 5202 and Our Choice of NRTIs

Initial antiretroviral therapy (ART) almost always consists of two nucleoside reverse transcriptase inhibitors (NRTIs) plus a third drug. For the NRTI backbone, current guidelines indicate a strong preference for tenofovir/FTC over abacavir/3TC, mainly because of virologic efficacy differences previously demonstrated in the ACTG 5202 study. In that 96-week trial, treatment-naive patients were stratified by viral load (< or ≥100,000 copies/mL) and randomized to receive either tenofovir/FTC or abacavir/3TC, each in combination with efavirenz or ritonavir-boosted atazanavir. Midway through the study, a review by the data and safety monitoring board revealed that, among patients with baseline viral loads ≥100,000 copies/mL, abacavir/3TC was ass…