BACKGROUND: Cabotegravir (GSK1265744) is an integrase strand transfer inhibitor 
in development as a long-acting (LA) intramuscular injectable suspension for 
HIV-1 pre-exposure prophylaxis (PrEP).
OBJECTIVE: We report participant outcomes from the phase IIa ECLAIR study 
related to tolerability, acceptability, and satisfaction of cabotegravir LA.
METHODS: The ECLAIR study (ClinicalTrials.gov identifier, NCT02076178) was a 
randomized, placebo-controlled study in healthy men not at high risk of 
acquiring HIV-1. Participants were randomized (5:1) to once-daily oral 
cabotegravir 30 mg or placebo tablets for 4 weeks, followed by gluteal 
intramuscular injections of cabotegravir LA 800 mg or saline placebo every 12 
weeks. The primary objective was to evaluate the safety of cabotegravir LA over 
three injection cycles (to Week 41). Secondary objectives assessed the 
tolerability, satisfaction, and acceptability of cabotegravir LA.
RESULTS: Among 115 participants who received injections in the cabotegravir 
(n = 94) and placebo (n = 21) groups, 93% (n = 87) and 95% (n = 20) completed 
the injection phase, respectively. Injection intolerability led to withdrawal in 
4 participants (4%) receiving cabotegravir LA. The most frequently reported 
Grade ≥2 adverse event was injection-site pain. Most participants (74% [n = 67]) 
receiving consecutive injections favored cabotegravir LA vs oral cabotegravir. 
Most participants were satisfied with cabotegravir LA (75% [n = 64]), were 
willing to continue (79% [n = 68]), and would recommend (87% [n = 75]) the 
therapy.
CONCLUSIONS: While Grade ≥2 injection-site pain was common, most participants 
reported overall satisfaction with and preference for cabotegravir LA, with few 
discontinuations due to injection intolerance. These findings support 
investigation of cabotegravir LA as an alternative to daily oral PrEP regimens.