(163) Long-term safety and efficacy of elexacaftor/tezacaftor/ivacaftor in children 6 years and older with cystic fibrosis and ≥1 F508del allele: 96-week interim results from an open-label extension study

Background: A 24-week, Phase 3 open-label study showed elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) was safe and efficacious in children 6 through 11 years of age with cystic fibrosis (CF) and at least one F508del-CFTR allele. All children who completed this trial entered a 192-week Phase 3, open-label extension study to assess long-term safety and efficacy. Here, we report results of the 96-week interim analysis (IA).

Methods: Dosing in the study is based on weight. Children who weigh < 30 kg receive ELX 100 mg once daily (qd)/TEZ 50 mg qd/IVA 75 mg every 12 hours (q12h) while children weighing ≥ 30 kg receive ELX 200 mg qd/TEZ 100 mg qd/IVA 150 mg q12h (adult dose). The primary endpoint is safety and tolerability; secondary endpoints include absolute changes in percent predicted FEV₁ (ppFEV₁), sweat chloride, CF Questionnaire-Revised (CFQ-R) respiratory domain score, body mass index, lung clearance index_2.5 (LCI_2.5), weight and weight-for-age z score, and height and height-for-age, z-score from parent study baseline, and number of pulmonary exacerbations (PEx) and CF-related hospitalizations. Data collection for the 96-week IA will be based on the date the last participant reaches Week 96 (Extended Week 96).

Results: 64 children (F508del/minimal function [F/MF] genotypes, n=36; F508del/ F508del [F/F] genotype, n=28) were enrolled and dosed. The last patient visit for this 96-week IA will take place in May 2022. Results from primary and secondary endpoints will be presented.

Conclusions: Pending

Acknowledgements: This work was funded by Vertex Pharmaceuticals Incorporated.

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