Efficacy and safety of a once-daily fixed-dose combination of abacavir/lamivudine compared with abacavir twice daily and lamivudine once daily as separate entities in antiretroviral-experienced HIV-1-infected patients (CAL30001 study)

Background: A one-tablet, once-daily abacavir/lamivudine fixed-dose combination (FDC) has been recently approved to treat HIV-1 infection. Methods: A randomized, open-label, parallel-group, multicenter study to compare the efficacy and safety of the FDC group to the separate entities (SE) group, in combination with tenofovir and a new protease inhibitor or nonncleoside reverse transcription inhibitor in antiretroviral-experienced adults experiencing virologic failure (VF). Eligible subjects had viral loads > 1000 copies/mL with :<= 3 nonnucleoside reverse transcription inhibitor-associated mutations. The primary efficacy end point was time-average changed from baseline (average area under the Curve minus baseline) in plasma HIV-1 RNA over 48 weeks. Results: A total of 186 subjects were enrolled. The average area under the curve minus baseline was - 1.65 and - 1.83 log(10) copies/ mL in the FDC and SE groups, respectively (intention to treat; 95% confidence interval: -0.13, 0.38). Patients in the FDC (50%) and SE groups (47%) achieved viral loads < 50 copies/mL based oil the time to loss of virologic response algorithm. VF was low and similar ill both groups (FDC, 16%; SE, 18%). Tolerability was similar between the 2 groups. Conclusions: The FDC group had noninferior efficacy over 48 weeks to the SE group in treatment-experienced subjects with VF.