Background:
Cabotegravir (CAB)+rilpivirine (RPV) administered monthly or Q2M is a complete long-acting (LA) regimen for maintaining HIV-1 suppression. We present results from SOLAR, the first randomized comparison of CAB+RPV LA Q2M vs. continued daily oral bictegravir/emtricitabine/tenofovir alafenamide (B/FTC/TAF).
Methods:
SOLAR (NCT04542070) is a Phase 3b, randomized (2:1), open-label, multicenter, noninferiority (NI) study assessing switching virologically suppressed adults to CAB+RPV LA (with/without oral lead-in [OLI]) Q2M vs. continuing B/FTC/TAF. The primary analysis was based on the pre-specified modified intention-to-treat exposed (mITT-E) population (n=11 excluded from the ITT-E for protocol deviation). The primary endpoint was the proportion with plasma HIV-1 RNA ≥50 c/mL (FDA Snapshot, 4% NI margin) at M11 (LA without OLI)/M12 (LA with OLI and B/FTC/TAF). Other endpoints were the proportion with plasma HIV-1 RNA < 50 c/mL (FDA Snapshot, –12% NI margin), incidence of confirmed virologic failure (CVF; 2 consecutive HIV-1 RNA ≥200 c/mL), safety, tolerability, treatment satisfaction (HIV Treatment Satisfaction Questionnaire status version [HIVTSQs]), and preference.
Results:
Of 670 participants (mITT-E), 447 switched to LA (n=173 [39%] with OLI; n=274 [61%] without OLI) and 223 (33%) continued B/FTC/TAF. Baseline (BL) characteristics were similar between arms; 18% were female sex at birth, 21% were Black, median age (range) was 37 years (18–74). At M11/12, noninferior efficacy of LA vs. B/FTC/TAF was demonstrated for the proportion with HIV-1 RNA ≥50 c/mL (Table). 2 (0.4%) and 3 (0.6%) participants receiving LA had CVF in the mITT-E and ITT-E populations, respectively; all developed resistance at failure. Excluding injection site reactions (ISRs), AEs and serious AEs were comparable between arms, although drug-related AEs were more frequent in the LA arm (20% vs. < 1%). More LA arm participants had AEs leading to withdrawal (6% vs. < 1%). Most ISRs were Grade 1 or 2 (98%). Mean adjusted HIVTSQs scores improved significantly (p< 0.001) for LA (+3.36) vs. B/FTC/TAF (–1.59) participants from BL (LA, 57.88; B/FTC/TAF, 58.38; descriptive) to M11/12. Most (90%, n=382/425) participants preferred LA vs. oral therapy (5%, n=21/425) at M11/12 or withdrawal.
Conclusions:
At M11/12, CAB+RPV LA Q2M demonstrated noninferior virologic efficacy vs. B/FTC/TAF. Switching to CAB+RPV LA from B/FTC/TAF was efficacious, well tolerated, improved treatment satisfaction, and was preferred by most participants.
SOLAR Key Efficacy and Safety Outcomes at Month 12