Clinical Effectiveness of Elexacaftor/Tezacftor/Ivacaftor in People with Cystic Fibrosis.

Rationale: The cystic fibrosis (CF) modulator drug elexacaftor/tezacaftor/ivacaftor (ETI) proved highly effective in controlled clinical trials for individuals with ≥1 F508del allele, which occurs in at least 85% of people with CF (PwCF). Objective: PROMISE is a post-approval study to understand the broad effects of ETI through 30 months clinical use in a more diverse US patient population with planned analyses after 6 months. Methods: Prospective, observational study in 487 PwCF age ≥12 years with ≥1 F508del allele starting ETI for the first time. Assessments occurred before and 1, 3, and 6 months into ETI therapy. Outcomes included change in ppFEV1, sweat chloride concentration, body mass index, and self-reported respiratory symptoms. Results: average age was 25.1 years. 44.1% entered the study using tezacaftor/ivacaftor or lumacaftor/ivacaftor while 6.7% were using ivacaftor, consistent with F508del homozygosity and G551D allele, respectively. At 6 months into ETI therapy, ppFEV1 improved 9.76 percentage points (95% CI 8.76, 10.76) from baseline, CFQ-R Respiratory Domain score improved 20.4 points (95% CI 18.3, 22.5), and sweat chloride decreased -41.7 mmol/L (95% CI 43.8, 39.6). BMI also significantly increased. Changes were larger in those naive to modulators but substantial in all groups, including those treated with ivacaftor at baseline. Conclusions: ETI by clinical prescription provided large improvements in lung function, respiratory symptoms, and BMI in a diverse population naive to modulator drug therapy, using existing two-drug combinations, or using ivacaftor alone. Each group also experienced significant reductions in sweat chloride concentration, which correlated with improved ppFEV1 in the overall study population.