Background:
Cabotegravir plus rilpivirine long-acting (CAB+RPV LA) administered every 2 months (Q2M) is the first and only complete LA regimen recommended for virologically suppressed people living with HIV-1. Here, we report HIV-1 RNA viral blips and target virus not detected (TND), as well as the impact of HIV-1 RNA blips on viral load measurements at Month 12 and confirmed virologic failure (CVF), in participants switching to CAB+RPV LA vs. continuing daily oral bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) through Month 12 in the SOLAR study.
Methods:
SOLAR (NCT04542070) is a Phase 3b, randomized (2:1), open-label, multicenter, noninferiority study assessing switching virologically suppressed adults to CAB+RPV LA Q2M vs. continuing BIC/FTC/TAF. The analysis was based on the modified intention-to-treat exposed (mITT-E) population (exclusion of one trial site for non-compliance to protocol entry criteria). HIV-1 RNA viral blips were defined as a single HIV-1 RNA value between 50 and <200 c/mL with adjacent values <50 c/mL. CVF was defined as two consecutive HIV-1 RNA ≥200 c/mL values. Plasma samples were analyzed for HIV-1 RNA viral load using the Abbott RealTime HIV-1 assay, and TND outcomes were provided for HIV-1 RNA <40 c/mL.
Results:
Of 670 participants (mITT-E), 447 (67%) switched to LA and 223 (33%) continued BIC/FTC/TAF. The proportion of participants with HIV-1 viral blips through Month 12 was 4% (n=19/447) in the CAB+RPV LA arm and 4% (n=9/223) in the BIC/FTC/TAF arm. Of participants with viral blips, 5% (n=1/19) and 11% (n=1/9) in the CAB+RPV LA and BIC/FTC/TAF arms, respectively, had HIV-1 RNA ≥50 c/mL at Month 12; no participants with HIV-1 RNA viral blips developed CVF. The proportions of participants with viral blips were consistently ≤1% of participants with available data across both treatment arms at any time point. TND outcomes at individual study visits were similar between study arms (CAB+RPV LA, 85–88%; BIC/FTC/TAF, 80–86%), and the proportions of participants with HIV-1 RNA <40 c/mL (CAB+RPV LA, 90–97%; BIC/FTC/TAF, 90–97%) were comparable between treatment arms through Month 12.
Conclusions:
The proportions of study participants with HIV-1 RNA viral blips, TND, and HIV-1 RNA <40 c/mL were similar between CAB+RPV LA and BIC/FTC/TAF through Month 12. HIV-1 viral blips with CAB+RPV LA did not appear to be associated with CVF, consistent with prior CAB+RPV LA Phase 3 clinical study data.
