884. Patient Adherence to Long-Acting Injectable Cabotegravir + Rilpivirine Through 48 Weeks of Maintenance Therapy in the Phase 3 ATLAS and FLAIR Studies

BACKGROUND: Cabotegravir (CAB) and rilpivirine (RPV) are under development as a novel long-acting (LA) regimen for maintenance of HIV virologic suppression. Pooled Week 48 data from pivotal Phase 3 trials demonstrated noninferiority of CAB LA + RPV LA vs. current antiretroviral regimen (CAR) on the primary endpoint, proportion of subjects with HIV-1 RNA ≥50 c/mL (1.9% and 1.7%, respectively). Adherence to dosing visits, use of oral dosing (bridging) to cover planned missed injections and injection tolerability were examined for subjects in the ATLAS and FLAIR studies. METHODS: Virologically suppressed subjects (HIV-1 RNA < 50 c/mL) were randomized to switch to CAB LA + RPV LA or to continue CAR. On-time injections occurred Q4 weeks within a +7-day dosing window of the projected dosing date. Adherence to LA therapy was calculated as the number of on-time injection visits divided by the number of expected dosing visits through Week 48. Injection visits outside the pre-specified window and missed injection visits with/without the use of oral dosing were quantified. Injection tolerability was assessed via adverse event reporting. RESULTS: A total of 14,682 injections of CAB and RPV were administered to 581 subjects during 6,920 injection visits. 98% of injection visits took place within the allowed ±7-day dosing window with 3,194 (46%) on the projected dosing date. Forty-six (<1%) injection visits were early and 106 (2%) were late. Oral bridging was used in 16 subjects overall; 8 planned missed injection visits were successfully covered, with no change to virologic suppression status. No subject with HIV-1 RNA ≥ 50 c/mL at Week 48 had missed/late injection visits. 25% (3,663/14,682) of injections were associated with local injection site reactions (ISRs). The most common ISR was pain (3,087/3,663 = 84%). Most ISRs were grade 1–2 (99%), short duration (median 3 days), with few associated discontinuations (<1%). CONCLUSION: Subjects receiving CAB LA + RPV LA demonstrated high rates of adherence to injection visits through week 48, with 98% of injections occurring within the ±7-day dosing window. Oral bridging with CAB and RPV was an effective strategy for maintaining viral load suppression to cover missed injection visits. Injections were well-tolerated with few associated discontinuations. [Image: see text] [Image: see text] DISCLOSURES: All Authors: No reported Disclosures.