Willingness of people with cystic fibrosis receiving elexacaftor/tezacaftor/ivacaftor (ETI) to participate in randomized modulator and inhaled antimicrobial clinical trials

•Willingness to enroll in clinical trials was assessed for those on CFTR modulators.•Willingness to enroll was associated with proposed trial length and comparator.•Shorter trials and active comparators were favored over alternatives.•Future studies in people on CFTR modulators will be feasible for some trial designs. To assess the feasibility of enrolling people with CF (pwCF) taking the CFTR modulator elexacaftor/tezacaftor/ivacaftor (ETI) in clinical trials of a new modulator. PwCF receiving ETI at CHEC-SC study (NCT03350828) enrollment were surveyed for interest in 2-week to 6-month placebo- (PC) and active-comparator (AC) modulator studies. Those taking inhaled antimicrobials (inhABX) were surveyed for interest in PC inhABX studies. Of 1791 respondents, 75% [95% CI 73, 77] would enroll in a 2-week PC modulator study versus 51% [49, 54] for a 6-month study; 82% [81, 84] and 63% [61, 65] would enroll in 2-week and 6 month AC studies; 77% [74, 80] of 551 taking inhABX would enroll in a 2-week PC inhABX study versus 59% [55, 63] for a 6-month study. Previous clinical trial experience increased willingness. Study designs will affect feasibility of future clinical trials of new modulators and inhABX in people receiving ETI.