Tezacaftor/ivacaftor in people with cystic fibrosis heterozygous for minimal function CFTR mutations

Abstract

Background: Tezacaftor/ivacaftor is a CFTR modulator approved to treat people with cystic fibrosis (pwCF) who are homozygous (F/F) or heterozygous for the F508del-CFTR mutation and a residual function mutation (F/RF). This randomized, double-blind, placebo-controlled Phase 3 study evaluated the efficacy, safety, tolerability, and pharmacokinetics (PK) of tezacaftor/ivacaftor in participants ≥12 years of age heterozygous for the F508del-CFTR mutation and a minimal function mutation (F/MF), which produces no CFTR protein or a protein unresponsive to tezacaftor/ivacaftor in vitro.

Methods: Participants were randomized 1:1 to receive tezacaftor/ivacaftor or placebo for 12 weeks. The primary endpoint was the absolute change from baseline in percent predicted forced expiratory volume in 1 second (ppFEV1) between the tezacaftor/ivacaftor and placebo groups through week 12. Key secondary endpoints included absolute change from baseline in CF Questionnaire-Revised respiratory domain scores and the number of pulmonary exacerbations through week 12 and the absolute change from baseline in body mass index at week 12. A prespecified interim analysis (IA) for futility was conducted when approximately 50% of a planned enrollment of 300 participants reached week 12 of the study.

Results: At the time of the IA, 83 participants were randomized to tezacaftor/ivacaftor and 85 to placebo; 165 participants completed treatment. The study failed to demonstrate that tezacaftor/ivacaftor significantly improved ppFEV1 or any of the key secondary endpoints and was terminated for futility. The safety profile and PK parameters of tezacaftor/ivacaftor were similar to those reported in prior studies in participants ≥12 years of age with CF.

Conclusions: Tezacaftor/ivacaftor did not show a clinically meaningful benefit in participants with F/MF genotypes but was generally safe and well tolerated, consistent with the safety profile reported in other Phase 3 studies (NCT02516410).

Keywords: Cystic fibrosis; Ivacaftor; Tezacaftor.

Conflict of interest statement

Declaration of Competing Interest All authors received nonfinancial support (assistance with manuscript preparation) from ArticulateScience LLC, which received funding from Vertex Pharmaceuticals Incorporated. Additional disclosures are as follows: DC, CAO, NA, and LTW are employees of Vertex Pharmaceuticals Incorporated and may own stock or stock options in Vertex Pharmaceuticals Incorporated. AM: Coordinator for the Vertex tezacaftor/ivacaftor clinical trial 661-107 and fees for their institution (Robert Debré Hospital, Paris, France) during the conduct of the study; participation in advisory boards and educational meetings with Vertex Pharmaceuticals Incorporated outside of the submitted work. CW: Income on a per-patient basis derived from pharmaceutical studies (Vertex Pharmaceuticals Incorporated and Boehringer-Ingelheim); research grant from Novo Nordisk Pharmaceuticals for the P/L-CF-IDEA study; Vertex Pharmaceuticals P/L honorarium to attend the CF International Advisory Board Meeting in February 2014; Vertex Pharmaceuticals P/L honorarium to attend CF Medical Advisory Board Meeting in Adelaide in April 2014; Novartis Pharmaceuticals P/L honorarium to present a symposium at the National Pediatric Congress in Lebanon in May 2014; Vertex Pharmaceuticals P/L return travel and honorarium for lecture & discussions at the European CF Conference in Gothenburg in June 2014; DKBmed, LLC honorarium to present symposium at the North American CF Conference Georgia in October 2014; Vertex Pharmaceuticals P/L honorarium to present as speaker in an educational meeting series in Brisbane and Sydney in April 2015; Vertex Pharmaceuticals P/L honorarium to attend the Vertex Steering Committee Meetings on the VX15-770-123 study in 2014; Vertex Pharmaceuticals P/L honorarium for Vertex Medical Advisory Board-Innovative endpoints in CF in August 2015; University of Miami honorarium for meeting attendance in 2015; Thorax honorarium for associate editor duties in Q3/Q4 2015; BMJ honorarium for work as a reviewer; Vertex Pharmaceuticals 2015 Chicago return flight and accommodation for work as investigator in lumacaftor study; Vertex Pharmaceuticals 2015–2017 honorarium for being a speaker at Vertex-sponsored educational meeting series in Australia; Vertex Pharmaceuticals 2016 Phoenix return flight and accommodation as investigator in the Next Gen study; Vertex Pharmaceuticals December 2016 honoraria for work as a speaker at a Vertex-sponsored educational meeting in Liverpool, UK; DKBmed eCF review issue honoraria in January 2017; Vertex Pharmaceuticals March 2017 honoraria for being a speaker at TSANZ meeting; Vertex Pharmaceuticals Incorporated 2014–2018 honorarium for acting as a consultant on the Vertex Orkambi 6-11 HTA Advisory Board, the Global Pediatric Advisory Committee, the Global Medical Advisory Board, and the VIA Grants Committee; Gilead Sciences Ltd. honorarium for meeting attendance on CF imaging; honorarium for In Vivo Academy Limited for webcast meeting attendance at ECFC 2018; Vertex Pharmaceuticals P/L honorarium to present as a speaker in an educational meeting at ECFC in Belgrade 2018; Vertex Pharmaceuticals Incorporated honorarium to attend the Next Gen Early Lifecycle Management Plan in London in 2018; Vertex Pharmaceuticals P/L to act as consultant and to render such services in the form of documents, advice, meetings, and conferences from October 2018 to present; Vertex Pharmaceuticals (Australia) P/L to attend as a steering committee member at the Medical Symposium Event (SHIFT 2019) in Perth in 2019; Vertex Pharmaceuticals P/L to attend the EU Real World Evidence steering committee in Amsterdam in 2019; Current board positions: International Advisory Board, Vertex Pharmaceuticals P/L; Associate Editor, Thorax; Associate Editor, Respirology. EK: Grants from Vertex Pharmaceuticals Incorporated during the conduct of the study; speaker honorarium and membership in scientific advisory board at Vertex Pharmaceuticals Incorporated outside the submitted work. HE: participated in an advisory board meeting with Vertex Pharmaceuticals Incorporated outside of the submitted work.

Copyright © 2020 The Author(s). Published by Elsevier B.V. All rights reserved.