Month 12 outcomes of switching to long-acting cabotegravir + rilpivirine with an oral lead-in versus continuing bictegravir/emtricitabine/tenofovir alafenamide in the Phase 3b randomized SOLAR study

Cabotegravir + rilpivirine (CAB + RPV) dosed every 2 months (Q2M) is the only complete long-acting (LA) regimen for maintaining HIV-1 virologic suppression. In some regions, prescribing information mandates a 4-week oral lead-in (OLI) before initiating CAB + RPV LA. To support clinical decision-making in these areas, we report a pre-specified analysis in adults living with HIV-1 who switched to CAB + RPV LA with an OLI versus continuing daily oral bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) for maintaining virologic suppression in the Phase 3b, randomized, open-label, SOLAR study. In SOLAR, participants with HIV-1 RNA <50 copies/mL were randomized (2:1) to either intramuscular CAB + RPV LA Q2M, with a 1-month optional once-daily OLI of CAB + RPV, or to continue daily oral BIC/FTC/TAF. Month 12 endpoints included virologic response, safety, and patient-reported outcomes. Of 670 participants, 173 (39 %) switched to CAB + RPV LA with OLI, 274 (61 %) switched to CAB + RPV LA starting directly with injections, and 223 (33 %) continued BIC/FTC/TAF. At Month 12, the proportions of participants with HIV-1 RNA ≥50 copies/mL (CAB + RPV LA OLI, 1 % [n = 2/173]; BIC/FTC/TAF, <1 % [n = 1/223]) and HIV-1 RNA <50 copies/mL (CAB + RPV LA OLI, 87 % [n = 151/173]; BIC/FTC/TAF, 93 % [n = 207/223]) were similar between arms. Excluding injection site reactions, adverse events were comparable between arms; however, more participants in the CAB + RPV LA OLI arm had adverse events leading to withdrawal (5 % [n = 8/173] versus <1 % [n = 2/227]). Overall, 87 % (n = 142/163) of participants who switched preferred CAB + RPV LA OLI to BIC/FTC/TAF. Switching to CAB + RPV LA OLI demonstrated comparable efficacy to continuing BIC/FTC/TAF, was well tolerated and preferred by most participants who switched. ClinicalTrials.gov; NCT04542070 (https://clinicaltrials.gov/study/NCT04542070).