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Della Sala A, Prono G, Hirsch E, Ghigo A. Role of Protein Kinase A-Mediated Phosphorylation in CFTR Channel Activity Regulation. Front Physiol 2021; 12:690247. [PMID: 34211404 PMCID: PMC8240754 DOI: 10.3389/fphys.2021.690247] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 05/10/2021] [Indexed: 11/17/2022] Open
Abstract
Cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel expressed on the apical membrane of epithelial cells, where it plays a pivotal role in chloride transport and overall tissue homeostasis. CFTR constitutes a unique member of the ATP-binding cassette transporter superfamily, due to its distinctive cytosolic regulatory (R) domain carrying multiple phosphorylation sites that allow the tight regulation of channel activity and gating. Mutations in the CFTR gene cause cystic fibrosis, the most common lethal autosomal genetic disease in the Caucasian population. In recent years, major efforts have led to the development of CFTR modulators, small molecules targeting the underlying genetic defect of CF and ultimately rescuing the function of the mutant channel. Recent evidence has highlighted that this class of drugs could also impact on the phosphorylation of the R domain of the channel by protein kinase A (PKA), a key regulatory mechanism that is altered in various CFTR mutants. Therefore, the aim of this review is to summarize the current knowledge on the regulation of the CFTR by PKA-mediated phosphorylation and to provide insights into the different factors that modulate this essential CFTR modification. Finally, the discussion will focus on the impact of CF mutations on PKA-mediated CFTR regulation, as well as on how small molecule CFTR regulators and PKA interact to rescue dysfunctional channels.
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Affiliation(s)
- Angela Della Sala
- Molecular Biotechnology Center, Department of Molecular Biotechnology and Health Sciences, University of Turin, Turin, Italy
| | | | - Emilio Hirsch
- Molecular Biotechnology Center, Department of Molecular Biotechnology and Health Sciences, University of Turin, Turin, Italy.,Kither Biotech S.r.l, Turin, Italy
| | - Alessandra Ghigo
- Molecular Biotechnology Center, Department of Molecular Biotechnology and Health Sciences, University of Turin, Turin, Italy.,Kither Biotech S.r.l, Turin, Italy
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McKone EF, DiMango EA, Sutharsan S, Barto TL, Campbell D, Ahluwalia N, Higgins M, Owen CA, Tullis E. A phase 3, randomized, double-blind, parallel-group study to evaluate tezacaftor/ivacaftor in people with cystic fibrosis heterozygous for F508del-CFTR and a gating mutation. J Cyst Fibros 2020; 20:234-242. [PMID: 33339768 DOI: 10.1016/j.jcf.2020.11.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 10/30/2020] [Accepted: 11/03/2020] [Indexed: 01/29/2023]
Abstract
BACKGROUND Tezacaftor (TEZ)/ivacaftor (IVA) is an approved CFTR modulator shown to be efficacious and generally safe and well tolerated in people ≥12 years of age with cystic fibrosis (CF) homozygous for the F508del-CFTR mutation or heterozygous for the F508del-CFTR mutation and a residual function mutation. Although previous studies with IVA alone showed clinical benefits in people with CFTR gating mutations, TEZ/IVA has not yet been evaluated in a Phase 3 study of participants heterozygous for F508del-CFTR and a gating mutation (F/gating genotypes). Here, we present results from a randomized, double-blind, IVA-controlled, parallel-group, Phase 3 study assessing the efficacy, safety, and pharmacokinetics (PK) of TEZ/IVA in participants ≥12 years of age with F/gating genotypes. METHODS Enrolled participants entered a 4-week IVA run-in period to create a stable IVA baseline. Participants were then randomized to receive IVA or TEZ/IVA for 8 weeks in an active comparator treatment period (ACTP). The primary endpoint was absolute change in percent predicted forced expiratory volume in 1 second (ppFEV1). Key secondary endpoints were relative change in ppFEV1 and absolute change in CF Questionnaire-Revised respiratory domain score. Secondary endpoints included absolute change in sweat chloride (SwCl) concentration, PK parameters, and safety. All endpoints except PK parameters and safety were assessed from baseline through Week 8. RESULTS Sixty-nine participants (92.0%) in the IVA group and 75 participants (98.7%) in the TEZ/IVA group completed treatment. No improvements were seen in efficacy endpoints from baseline at the end of the IVA run-in period through the end of the ACTP in the IVA group. No significant differences in ppFEV1 or any key secondary endpoint were observed between the IVA and TEZ/IVA groups. SwCl concentrations decreased more in the TEZ/IVA versus IVA group during the ACTP. The safety profile and PK parameters of TEZ/IVA were consistent with those of previous studies in participants ≥12 years of age with CF. CONCLUSIONS This Phase 3 study showed that the dual-combination regimen of TEZ/IVA demonstrated clinical efficacy but did not have significantly greater clinical efficacy than IVA alone in participants ≥12 years of age with F/gating genotypes. However, as reported in other studies, TEZ/IVA was generally safe and well tolerated (NCT02412111).
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Affiliation(s)
- Edward F McKone
- St. Vincent's University Hospital, Elm Park, Dublin 4, Ireland.
| | - Emily A DiMango
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, Columbia University, 622 West 168 Street, PH 8 East, Room 101, New York, NY 10032, United States.
| | - Sivagurunathan Sutharsan
- Division of Cystic Fibrosis, Department of Pulmonary Medicine, University Medicine Essen-Ruhrlandklinik, University of Duisburg-Essen, Essen, Germany.
| | - Tara Lynn Barto
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, Baylor College of Medicine, 7200 Cambridge Street, Houston, TX 77030.
| | - Daniel Campbell
- Vertex Pharmaceuticals Incorporated, 50 Northern Avenue, Boston, MA 02210, United States.
| | - Neil Ahluwalia
- Vertex Pharmaceuticals Incorporated, 50 Northern Avenue, Boston, MA 02210, United States.
| | - Mark Higgins
- Vertex Pharmaceuticals (Europe) Limited, Level 9, Paddington Central, 2 Kingdom Street, London W2 6BD, United Kingdom.
| | - Caroline A Owen
- Vertex Pharmaceuticals Incorporated, 50 Northern Avenue, Boston, MA 02210, United States.
| | - Elizabeth Tullis
- Division of Respirology, Department of Medicine, St. Michael's Hospital, University of Toronto, 30 Bond Street, Toronto, Ontario M5B 1W8, Canada.
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Davies JC, Sermet-Gaudelus I, Naehrlich L, Harris RS, Campbell D, Ahluwalia N, Short C, Haseltine E, Panorchan P, Saunders C, Owen CA, Wainwright CE. A phase 3, double-blind, parallel-group study to evaluate the efficacy and safety of tezacaftor in combination with ivacaftor in participants 6 through 11 years of age with cystic fibrosis homozygous for F508del or heterozygous for the F508del-CFTR mutation and a residual function mutation. J Cyst Fibros 2020; 20:68-77. [PMID: 32967799 DOI: 10.1016/j.jcf.2020.07.023] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 07/24/2020] [Accepted: 07/26/2020] [Indexed: 12/21/2022]
Abstract
BACKGROUND The CFTR modulator tezacaftor/ivacaftor was efficacious and generally safe and well tolerated in Phase 3 studies in participants ≥12 years of age with cystic fibrosis (CF) homozygous for the F508del-CFTR mutation or heterozygous with a residual function-CFTR mutation (F/F or F/RF respectively). We evaluated tezacaftor/ivacaftor's efficacy and safety over 8 weeks in participants 6 through 11 years of age with these mutations. METHODS Participants were randomized 4:1 to tezacaftor/ivacaftor or a blinding group (placebo for F/F, ivacaftor for F/RF). The primary endpoint was within-group change from baseline in the lung clearance index 2·5 (LCI2·5) through Week 8. Secondary endpoints were change from baseline in sweat chloride (SwCl), cystic fibrosis questionnaire-revised (CFQ-R) respiratory domain score, and safety. RESULTS Sixty-seven participants received at least one study drug dose. Of those, 54 received tezacaftor/ivacaftor (F/F, 42; F/RF, 12), 10 placebo, and 3 ivacaftor; 66 completed the study. The within-group change in LCI2·5 was significantly reduced (improved) by -0·51 (95% CI: -0·74, -0·29). SwCl concentration decreased (improved) by -12·3 mmol/L and CFQ-R respiratory domain score increased (improved, nonsignificantly) by 2·3 points. There were no serious adverse events (AEs) or AEs leading to tezacaftor/ivacaftor discontinuation or interruption. The most common AEs (≥10%) in participants receiving tezacaftor/ivacaftor were cough, headache, and productive cough. CONCLUSIONS Tezacaftor/ivacaftor improved lung function (assessed using LCI) and CFTR function (measured by SwCl concentration) in participants 6 through 11 years of age with F/F or F/RF genotypes. Tezacaftor/ivacaftor was safe and well tolerated; no new safety concerns were identified.
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Affiliation(s)
- Jane C Davies
- National Heart and Lung Institute, Imperial College London, London, United Kingdom; Royal Brompton & Harefield NHS Foundation Trust, London, United Kingdom.
| | - Isabelle Sermet-Gaudelus
- INSERM U1151, Institut Necker Enfants Malades, Université Paris Sorbonne, Paris, France, Hôpital Necker-Enfants malades, Paris, France
| | - Lutz Naehrlich
- Department of Pediatrics, Justus Liebig University Giessen, Giessen, Germany; Universities of Giessen and Marburg Lung Center, The German Center for Lung Research, Giessen, Germany
| | - R Scott Harris
- Vertex Pharmaceuticals Incorporated, Boston, MA, United States
| | - Daniel Campbell
- Vertex Pharmaceuticals Incorporated, Boston, MA, United States
| | - Neil Ahluwalia
- Vertex Pharmaceuticals Incorporated, Boston, MA, United States
| | - Christopher Short
- National Heart and Lung Institute, Imperial College London, London, United Kingdom; Royal Brompton & Harefield NHS Foundation Trust, London, United Kingdom
| | - Eric Haseltine
- Vertex Pharmaceuticals Incorporated, Boston, MA, United States
| | - Paul Panorchan
- Vertex Pharmaceuticals Incorporated, Boston, MA, United States
| | - Clare Saunders
- National Heart and Lung Institute, Imperial College London, London, United Kingdom; Royal Brompton & Harefield NHS Foundation Trust, London, United Kingdom
| | - Caroline A Owen
- Vertex Pharmaceuticals Incorporated, Boston, MA, United States
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