Long-term effectiveness of unboosted atazanavir plus abacavir/lamivudine in subjects with virological suppression: A prospective cohort study.

Effectiveness data of an unboosted atazanavir (ATV) with abacavir/lamivudine (ABC/3TC) switch strategy in clinical routine are scant.We evaluated treatment outcomes of ATV + ABC/3TC in pretreated subjects in the EuroSIDA cohort when started with undetectable plasma HIV-1 viral load (pVL), performing a time to loss of virological response (TLOVR <50 copies/mL) and a snapshot analysis at 48, 96, and 144 weeks. Virological failure (VF) was defined as confirmed pVL >50 copies/mL.We included 285 subjects, 67% male, with median baseline CD4 530 cells, and 44 months with pVL ≤50 copies/mL. The third drug in the previous regimen was ritonavir-boosted atazanavir (ATV/r) in 79 (28%), and another ritonavir-boosted protease inhibitor (PI/r) in 29 (10%). Ninety (32%) had previously failed with a PI. Proportions of people with virological success at 48/96/144 weeks were 90%/87%/88% (TLOVR) and 74%/67%/59% (snapshot analysis), respectively. The rates of VF were 8%/8%/6%. Rates of adverse events leading to study discontinuation were 0.4%/1%/2%. The multivariable adjusted analysis showed an association between VF and nadir CD4+ (hazard ratio [HR] 0.63 [95% confidence interval [CI]: 0.42-0.93] per 100 cells higher), time with pVL ≤50 copies/mL (HR 0.87 [95% CI: 0.79-0.96] per 6 months longer), and previous failure with a PI (HR 2.78 [95% CI: 1.28-6.04]). Resistance selection at failure was uncommon.A switch to ATV + ABC/3TC in selected subjects with suppressed viremia was associated with low rates of VF and discontinuation due to adverse events, even in subjects not receiving ATV/r. The strategy might be considered in those with long-term suppression and no prior PI failure.
Competing Interests: Authorship: JML has been a member of speakers’ bureaus and received fees from lectures, educational activities, or for participating in advisory boards from Janssen-Cilag, Merck, Sharp & Dohme, ViiV Healthcare, Gilead Sciences, and Bristol-Myers Squibb. CP has received a research grant from Gilead, and has received fees for educational activities from Abbott, Glaxo Smith Kline, and Merck Sharp & Dohme. KF has received honoraria from Gilead Sciences and Bristol-Myers Squibb and research grants from Gilead Sciences. H-JS has received speaker honoraria from AbbVie, ViiV, Bristol-Myers Squibb, Merck Sharp & Dohme, Gilead Sciences, and Janssen Cilag, and scientific advice from Bristol-Myers Squibb, Merck Sharp & Dohme, Gilead Sciences, and Janssen Cilag. RP has served as a consultant or advisor to Gilead Sciences, Inc, and ViiV Healthcare, and has received research grants from ViiV Healthcare, Gilead Sciences, and MSD. JML led the design of the analysis on behalf of the EuroSIDA Study group, had full access to all the data in the study, and had final responsibility for the decision to submit for publication. EuroSIDA gathered and assured quality of the data collected from the participating sites. AC-L analyzed the data based on the statistical analysis plan. The manuscript was written by JML, edited by AC-L, and reviewed by the writing group members. The writing group vouches for the data, analysis, and content of the manuscript. The remaining authors disclose no conflicts of interest.