Abstract
Background Elexacaftor-tezacaftor-ivacaftor has been approved in Europe for people with cystic fibrosis with at least one F508del CFTR variant. Additionally, it is approved by the US Food and Drug Administration (FDA) for people with cystic fibrosis with at least one of 177 rare variants. The aims of this study were to describe the clinical response to elexacaftor-tezacaftor-ivacaftor for people with cystic fibrosis without a F508del CFTR variant in France and to determine CFTR variant responsiveness to elexacaftor-tezacaftor-ivacaftor based on the observed clinical response. Methods The French compassionate programme expanded access to elexacaftor-tezacaftor-ivacaftor to people with cystic fibrosis, aged 6 years and older, without a F508del variant, excluding those with two variants previously characterised as non-responsive. Participants at France's 47 cystic fibrosis centres were given a 4-6 week trial of elexacaftor-tezacaftor-ivacaftor and response was determined by a centralised committee based on evolution of clinical data, lung function, and sweat chloride concentration. Responsiveness of individual CFTR variants was derived from observed clinical responses. Findings The first compassionnate programme was launched on May 19, 2022; by March 8, 2024, 516 people with cystic fibrosis had been identified for inclusion in this real-word study: 37 were not included due to the presence of two variants previously characterised as non-responsive to elexacaftor-tezacaftor-ivacaftor, and 479 (229 females [48%] and 250 males [52%]) received elexacaftor-tezacaftor-ivacaftor for 4-6 weeks. Among 443 participants who received no CFTR modulator before elexacaftor-tezacaftor-ivacaftor, 83 had at least one FDAapproved variant, of whom 81 (98%) were responders and continued elexacaftor-tezacaftor-ivacaftor; in responders, mean absolute change in sweat chloride was -44•5 mmol/L (95% CI -39•1 to -49•8) and percentage of predicted FEV 1 (ppFEV 1 ) was 11•1 percentage points (95% CI 8•4 to 13•7; both comparisons p<0•0001). Among 360 participants with no FDA-approved variant and no previous CFTR modulator, 177 (49%) were responders; in responders, mean absolute change in sweat chloride was -20•5 mmol/L (-17•2 to -23•8) and ppFEV 1 was 13•2 percentage points (11•4 to 15•0; both comparisons p<0•0001). Among 36 participants who were receiving ivacaftor before elexacaftortezacaftor-ivacaftor, 32 (89%) continued elexacaftor-tezacaftor-ivacaftor. Of 251 individual CFTR variants, 64 (28 FDA-approved) were classified as responsive or possibly responsive to elexacaftor-tezacaftor-ivacaftor, and 123 (two FDA-approved) as non-responsive or possibly non-responsive to elexacaftor-tezacaftor-ivacaftor. Interpretation In France, over half of the population with cystic fibrosis without a F508del variant responded to elexacaftor-tezacaftor-ivacaftor, with most responders having no FDA-approved variant. The treatment period was relatively short and further research is warranted to describe the long-term safety and effectiveness of elexacaftortezacaftor-ivacaftor in this population.