https://clinicaltrials.gov/study/NCT06413368

15 patients 0-17 years with Cystic Fibrosis

VX-121/VX-661/VX-561 Film-coated tablet, Kalydeco 75 mg film-coated tablets, VX-445/VX-661/VX-770 film-coated fixed-dose combination tablet, VX-121/VX-661/VX-561 Film-coated tablet, Kaftrio 37.5 mg/25 mg/50 mg film-coated tablets, Kalydeco 150 mg film-coated tablets, VX-445/VX-661/VX-770 fixed-dose combination tablet

Part A: PK parameters of VX-121, TEZ, D-IVA, and relevant metabolites, Part A: Safety and tolerability as determined by adverse events (AEs), clinical laboratory values, standard 12 lead ECGs, vital signs, and pulse oximetry, Part B: Safety and tolerability as determined by AEs, clinical laboratory values, standard 12-lead ECGs, vital signs, and pulse oximetry