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Oliver KE, Carlon MS, Pedemonte N, Lopes-Pacheco M. The revolution of personalized pharmacotherapies for cystic fibrosis: what does the future hold? Expert Opin Pharmacother 2023; 24:1545-1565. [PMID: 37379072 PMCID: PMC10528905 DOI: 10.1080/14656566.2023.2230129] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 06/16/2023] [Accepted: 06/23/2023] [Indexed: 06/29/2023]
Abstract
INTRODUCTION Cystic fibrosis (CF), a potentially fatal genetic disease, is caused by loss-of-function mutations in the gene encoding for the CFTR chloride/bicarbonate channel. Modulator drugs rescuing mutant CFTR traffic and function are now in the clinic, providing unprecedented breakthrough therapies for people with CF (PwCF) carrying specific genotypes. However, several CFTR variants are unresponsive to these therapies. AREA COVERED We discussed several therapeutic approaches that are under development to tackle the fundamental cause of CF, including strategies targeting defective CFTR mRNA and/or protein expression and function. Alternatively, defective chloride secretion and dehydration in CF epithelia could be restored by exploiting pharmacological modulation of alternative targets, i.e., ion channels/transporters that concur with CFTR to maintain the airway surface liquid homeostasis (e.g., ENaC, TMEM16A, SLC26A4, SLC26A9, and ATP12A). Finally, we assessed progress and challenges in the development of gene-based therapies to replace or correct the mutant CFTR gene. EXPERT OPINION CFTR modulators are benefiting many PwCF responsive to these drugs, yielding substantial improvements in various clinical outcomes. Meanwhile, the CF therapy development pipeline continues to expand with the development of novel CFTR modulators and alternative therapeutic strategies with the ultimate goal of providing effective therapies for all PwCF in the foreseeable future.
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Affiliation(s)
- Kathryn E. Oliver
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, USA
- Center for Cystic Fibrosis and Airways Disease Research, Emory University and Children’s Healthcare of Atlanta, Atlanta, Georgia, USA
| | - Marianne S. Carlon
- Laboratory of Respiratory Diseases and Thoracic Surgery (BREATHE), Department of Chronic Diseases and Metabolism, KU Leuven, Leuven, Belgium
- Center for Molecular Medicine, KU Leuven, Leuven, Belgium
| | | | - Miquéias Lopes-Pacheco
- Biosystems & Integrative Sciences Institute (BioISI), Faculty of Sciences, University of Lisbon, Lisbon, Portugal
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Chen J, Thrasher K, Fu L, Wang W, Aghamohammadzadeh S, Wen H, Tang L, Keeling KM, Falk Libby E, Bedwell DM, Rowe SM. The synthetic aminoglycoside ELX-02 induces readthrough of G550X-CFTR producing superfunctional protein that can be further enhanced by CFTR modulators. Am J Physiol Lung Cell Mol Physiol 2023; 324:L756-L770. [PMID: 37014818 PMCID: PMC10202470 DOI: 10.1152/ajplung.00038.2023] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/29/2023] [Accepted: 04/02/2023] [Indexed: 04/05/2023] Open
Abstract
Ten percent of cystic fibrosis (CF) patients carry a premature termination codon (PTC); no mutation-specific therapies exist for these individuals. ELX-02, a synthetic aminoglycoside, suppresses translation termination at PTCs (i.e., readthrough) by promoting the insertion of an amino acid at the PTC and restoring expression of full-length CFTR protein. The identity of amino acids inserted at PTCs affects the processing and function of the resulting full-length CFTR protein. We examined readthrough of the rare G550X-CFTR nonsense mutation due to its unique properties. We found that forskolin-induced swelling in G550X patient-derived intestinal organoids (PDOs) was significantly higher than in G542X PDOs (both UGA PTCs) with ELX-02 treatment, indicating greater CFTR function from the G550X allele. Using mass spectrometry, we identified tryptophan as the sole amino acid inserted in the G550X position during ELX-02- or G418-mediated readthrough, which differs from the three amino acids (cysteine, arginine, and tryptophan) inserted in the G542X position after treatment with G418. Compared with wild-type CFTR, Fischer rat thyroid (FRT) cells expressing the G550W-CFTR variant protein exhibited significantly increased forskolin-activated Cl- conductance, and G550W-CFTR channels showed increased PKA sensitivity and open probability. After treatment with ELX-02 and CFTR correctors, CFTR function rescued from the G550X allele in FRTs reached 20-40% of the wild-type level. These results suggest that readthrough of G550X produces greater CFTR function because of gain-of-function properties of the CFTR readthrough product that stem from its location in the signature LSGGQ motif found in ATP-binding cassette (ABC) transporters. G550X may be a particularly sensitive target for translational readthrough therapy.NEW & NOTEWORTHY We found that forskolin-induced swelling in G550X-CFTR patient-derived intestinal organoids (PDOs) was significantly higher than in G542X-CFTR PDOs after treatment with ELX-02. Tryptophan (W) was the sole amino acid inserted in the G550X position after readthrough. Resulting G550W-CFTR protein exhibited supernormal CFTR activity, PKA sensitivity, and open probability. These results show that aminoglycoside-induced readthrough of G550X produces greater CFTR function because of the gain-of-function properties of the CFTR readthrough product.
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Affiliation(s)
- Jianguo Chen
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Kari Thrasher
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, United States
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Lianwu Fu
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, United States
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Wei Wang
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | | | - Hui Wen
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Liping Tang
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Kim M Keeling
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, United States
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Emily Falk Libby
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - David M Bedwell
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, United States
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Steven M Rowe
- Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
- Gregory Fleming James Cystic Fibrosis Research Center, University of Alabama at Birmingham, Birmingham, Alabama, United States
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3
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Foucaud P, Mercier JC. CFTR pharmacological modulators: A great advance in cystic fibrosis management. Arch Pediatr 2023; 30:1-9. [PMID: 36509624 DOI: 10.1016/j.arcped.2022.11.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 09/16/2022] [Accepted: 11/11/2022] [Indexed: 12/13/2022]
Abstract
Cystic fibrosis is a severe monogenic disease that affects around 7400 patients in France. More than 2100 mutations in the cystic fibrosis conductance transmembrane regulator (CFTR), the gene encoding for an epithelial ion channel that normally transports chloride and bicarbonate, lead to mucus dehydration and impaired bronchial clearance. Systematic neonatal screening in France since 2002 has enabled early diagnosis of cystic fibrosis. Although highly demanding, supportive treatments including daily chest physiotherapy, inhaled aerosol therapy, frequent antibiotic courses, nutritional and pancreatic extracts have improved the prognosis. Median age at death is now beyond 30 years. Ivacaftor was the first CFTR modulator found to both reduce sweat chloride concentration and improve pulmonary function in the rare CFTR gating mutations. Combinations of modulators such as lumacaftor + ivacaftor or tezacaftor + ivacaftor were found to improve pulmonary function both in patients homozygous for the F508del mutation characterized by the lack of CFTR protein and those heterozygous for F508del with minimal CFTR activity. The triple combination of ivacaftor + tezacaftor + elexacaftor was recently shown to significantly improve pulmonary function and quality of life, to normalize sweat chloride concentration, and to reduce the need for antibiotic therapy in patients with at least one F508del mutation (83% in France). These impressive data, however, need to be confirmed in the long term. Nevertheless, it is encouraging to hear treated patients testify about their markedly improved quality of life and to observe that the number of lung transplants for cystic fibrosis decreased dramatically in France after 2020, despite the COVID pandemic, with no increase in deaths without lung transplant.
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Affiliation(s)
- P Foucaud
- Vice-Président de l'Association Vaincre la Mucoviscidose, 181 Rue de Tolbiac, Paris 75013, France.
| | - J C Mercier
- Membre de la Commission de Transparence, Haute Autorité de Santé, 5 avenue du Stade de France, Saint Denis 93210, France
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Pranke IM, Varilh J, Hatton A, Faucon C, Girodon E, Dreano E, Chevalier B, Karri S, Reix P, Durieu I, Bidou L, Namy O, Taulan M, Hinzpeter A, Sermet-Gaudelus I. The U UGA C sequence provides a favorable context to ELX-02 induced CFTR readthrough. J Cyst Fibros 2022:S1569-1993(22)01392-3. [DOI: 10.1016/j.jcf.2022.10.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 09/22/2022] [Accepted: 10/24/2022] [Indexed: 11/18/2022]
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Fang X, Yeh JT, Hwang TC. Pharmacological Responses of the G542X-CFTR to CFTR Modulators. Front Mol Biosci 2022; 9:921680. [PMID: 35813815 PMCID: PMC9263564 DOI: 10.3389/fmolb.2022.921680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Accepted: 05/16/2022] [Indexed: 11/13/2022] Open
Abstract
Cystic fibrosis (CF) is a lethal hereditary disease caused by loss-of-function mutations of the chloride channel cystic fibrosis transmembrane conductance regulator (CFTR). With the development of small-molecule CFTR modulators, including correctors that facilitate protein folding and expression and potentiators that promote channel activity, about 90% of the CF patients are now receiving efficacious target therapies. G542X-CFTR, a premature termination codon (PTC) mutation, is the most common disease-associated mutation found in the remaining 10% of patients that await effective drugs to rectify the fundamental defects caused by PTC. In this study, we employed biophysical and biochemical techniques to characterize the pharmacological responses of the translational products of G542X-CFTR to a range of new CFTR modulators. Specifically, we identified two different proteins translated from the G542X-CFTR cDNA using western blotting: the C-terminus truncated protein that responds to the C1 corrector which binds to the N-terminal part of the protein and a full-length CFTR protein through the read-through process. Electrophysiological data suggest that the read-through protein, but not the C-terminus truncated one, is functional and responds well to CFTR potentiators despite a lower open probability compared to wild-type CFTR. As the expression of the read-through products can be increased synergistically with the read-through reagent G418 and C1 corrector, but not with combinations of different types of correctors, we concluded that an efficacious read-through reagent is a prerequisite for mitigating the deficits of G542X-CFTR. Moreover, the CFTR potentiators may help improve the effectiveness of future combinational therapy for patients carrying PTCs such as G542X.
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Affiliation(s)
- Xinxiu Fang
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States
| | - Jiunn-Tyng Yeh
- School of Medicine, National Yang Ming Chiao Tung University College of Medicine, Taipei, Taiwan
- *Correspondence: Jiunn-Tyng Yeh,
| | - Tzyh-Chang Hwang
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States
- Department of Pharmacology, National Yang Ming Chiao Tung University College of Medicine, Taipei, Taiwan
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Shaughnessy CA, Yadav S, Bratcher PE, Zeitlin PL. Receptor-mediated activation of CFTR via prostaglandin signaling pathways in the airway. Am J Physiol Lung Cell Mol Physiol 2022; 322:L305-L314. [PMID: 35020527 PMCID: PMC8858663 DOI: 10.1152/ajplung.00388.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Cystic fibrosis (CF) is a genetic disease caused by mutations of the gene encoding a cAMP-activated Cl- channel, the cystic fibrosis transmembrane conductance regulator (CFTR). CFTR modulator therapies consist of small-molecule drugs that rescue mutant CFTR. Regimens of single or combinations of CFTR modulators still rely on endogenous levels of cAMP to regulate CFTR activity. We investigated CFTR activation by the natural mediator prostaglandin E2 (PGE2) and lubiprostone (a Food and Drug Administration-approved drug known to target prostaglandin receptors) and tested the hypothesis that receptor-mediated CFTR activators can be used in combination with currently available CFTR modulators to increase function of mutant CFTR. Primary-cultured airway epithelia were assayed in Ussing chambers. Experimental CFTR activators and established CFTR modulators were applied for 24 h and/or acutely and analyzed for their effect on CFTR activity as measured by changes in short-circuit current (ISC). In non-CF airway epithelia, acute application of lubiprostone and PGE2 activated CFTR to the levels comparable to forskolin (Fsk). Pretreatment (24 h) with antagonists to prostaglandin receptors EP2 and EP4 abolished the ability of lubiprostone to acutely activate CFTR. In F508del homozygous airway epithelia pretreated with the triple combination of elexacaftor, tezacaftor, and ivacaftor (ELEXA/TEZ/IVA; i.e., Trikafta), acute application of lubiprostone was able to maximally activate CFTR. Prolonged (24 h) cotreatment of F508del homozygous epithelia with ELEXA/TEZ/IVA and lubiprostone increased acute CFTR activation by ∼60% compared with the treatment with ELEXA/TEZ/IVA alone. This work establishes the feasibility of targeting prostaglandin receptors to activate CFTR on the airway epithelia and demonstrates that cotreatment with lubiprostone can further restore modulator-rescued CFTR.
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Affiliation(s)
| | - Sangya Yadav
- 1Department of Pediatrics, National Jewish Health, Denver, Colorado
| | - Preston E. Bratcher
- 1Department of Pediatrics, National Jewish Health, Denver, Colorado,2Department of Pediatrics, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
| | - Pamela L. Zeitlin
- 1Department of Pediatrics, National Jewish Health, Denver, Colorado,2Department of Pediatrics, University of Colorado Denver, Anschutz Medical Campus, Aurora, Colorado
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Michaels WE, Pena-Rasgado C, Kotaria R, Bridges RJ, Hastings ML. Open reading frame correction using splice-switching antisense oligonucleotides for the treatment of cystic fibrosis. Proc Natl Acad Sci U S A 2022; 119:e2114886119. [PMID: 35017302 PMCID: PMC8784102 DOI: 10.1073/pnas.2114886119] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 12/03/2021] [Indexed: 12/11/2022] Open
Abstract
CFTR gene mutations that result in the introduction of premature termination codons (PTCs) are common in cystic fibrosis (CF). This mutation type causes a severe form of the disease, likely because of low CFTR messenger RNA (mRNA) expression as a result of nonsense-mediated mRNA decay, as well as the production of a nonfunctional, truncated CFTR protein. Current therapeutics for CF, which target residual protein function, are less effective in patients with these types of mutations due in part to low CFTR protein levels. Splice-switching antisense oligonucleotides (ASOs), designed to induce skipping of exons in order to restore the mRNA open reading frame, have shown therapeutic promise preclinically and clinically for a number of diseases. We hypothesized that ASO-mediated skipping of CFTR exon 23 would recover CFTR activity associated with terminating mutations in the exon, including CFTR p.W1282X, the fifth most common mutation in CF. Here, we show that CFTR lacking the amino acids encoding exon 23 is partially functional and responsive to corrector and modulator drugs currently in clinical use. ASO-induced exon 23 skipping rescued CFTR expression and chloride current in primary human bronchial epithelial cells isolated from a homozygote CFTR-W1282X patient. These results support the use of ASOs in treating CF patients with CFTR class I mutations in exon 23 that result in unstable CFTR mRNA and truncations of the CFTR protein.
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Affiliation(s)
- Wren E Michaels
- Center for Genetic Diseases, Chicago Medical School, Rosalind Franklin University of Science and Medicine, North Chicago, IL 60064
- School of Graduate and Postdoctoral Studies, Rosalind Franklin University of Science and Medicine, North Chicago, IL 60064
| | - Cecilia Pena-Rasgado
- Center for Genetic Diseases, Chicago Medical School, Rosalind Franklin University of Science and Medicine, North Chicago, IL 60064
| | - Rusudan Kotaria
- Center for Genetic Diseases, Chicago Medical School, Rosalind Franklin University of Science and Medicine, North Chicago, IL 60064
| | - Robert J Bridges
- Center for Genetic Diseases, Chicago Medical School, Rosalind Franklin University of Science and Medicine, North Chicago, IL 60064;
| | - Michelle L Hastings
- Center for Genetic Diseases, Chicago Medical School, Rosalind Franklin University of Science and Medicine, North Chicago, IL 60064;
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Integrity and Stability of PTC Bearing CFTR mRNA and Relevance to Future Modulator Therapies in Cystic Fibrosis. Genes (Basel) 2021; 12:genes12111810. [PMID: 34828417 PMCID: PMC8621375 DOI: 10.3390/genes12111810] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/16/2021] [Accepted: 11/18/2021] [Indexed: 12/26/2022] Open
Abstract
Major advances have recently been made in the development and application of CFTR (cystic fibrosis transmembrane conductance regulator) mutation class-specific modulator therapies, but to date, there are no approved modulators for Class I mutations, i.e., those introducing a premature termination codon (PTC) into the CFTR mRNA. Such mutations induce nonsense-mediated decay (NMD), a cellular quality control mechanism that reduces the quantity of PTC bearing mRNAs, presumably to avoid translation of potentially deleterious truncated CFTR proteins. The NMD-mediated reduction of PTC-CFTR mRNA molecules reduces the efficacy of one of the most promising approaches to treatment of such mutations, namely, PTC readthrough therapy, using molecules that induce the incorporation of near-cognate amino acids at the PTC codon, thereby enabling translation of a full-length protein. In this study, we measure the effect of three different PTC mutations on the abundance, integrity, and stability of respective CFTR mRNAs, using CFTR specific RT-qPCR-based assays. Altogether, our data suggest that optimized rescue of PTC mutations has to take into account (1) the different steady-state levels of the CFTR mRNA associated with each specific PTC mutation; (2) differences in abundance between the 3' and 5' regions of CFTR mRNA, even following PTC readthrough or NMD inhibition; and (3) variable effects on CFTR mRNA stability for each specific PTC mutation.
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Cohen-Cymberknoh M, Slae M, Wilschanski M. A Green Light for Stop Mutations. Am J Respir Cell Mol Biol 2021; 64:531-532. [PMID: 33705685 PMCID: PMC8086040 DOI: 10.1165/rcmb.2021-0060ed] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Malena Cohen-Cymberknoh
- Faculty of Medicine Hebrew University Jerusalem, Israel.,Pediatric Pulmonology Unit.,Cystic Fibrosis Center Hadassah-Hebrew University Medical Center Jerusalem, Israel
| | - Mordechai Slae
- Faculty of Medicine Hebrew University Jerusalem, Israel.,Cystic Fibrosis Center and.,Pediatric Gastroenterology Unit Hadassah-Hebrew University Medical Center Jerusalem, Israel
| | - Michael Wilschanski
- Faculty of Medicine Hebrew University Jerusalem, Israel.,Cystic Fibrosis Center and.,Pediatric Gastroenterology Unit Hadassah-Hebrew University Medical Center Jerusalem, Israel
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Bergeron C, Cantin AM. New Therapies to Correct the Cystic Fibrosis Basic Defect. Int J Mol Sci 2021; 22:ijms22126193. [PMID: 34201249 PMCID: PMC8227161 DOI: 10.3390/ijms22126193] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 05/31/2021] [Accepted: 06/04/2021] [Indexed: 12/24/2022] Open
Abstract
Rare diseases affect 400 million individuals worldwide and cause significant morbidity and mortality. Finding solutions for rare diseases can be very challenging for physicians and researchers. Cystic fibrosis (CF), a genetic, autosomal recessive, multisystemic, life-limiting disease does not escape this sad reality. Despite phenomenal progress in our understanding of this disease, treatment remains difficult. Until recently, therapies for CF individuals were focused on symptom management. The discovery of the cystic fibrosis transmembrane conductance regulator (CFTR) gene and its product, a protein present at the apical surface of epithelial cells regulating ion transport, allowed the scientific community to learn about the basic defect in CF and to study potential therapies targeting the dysfunctional protein. In the past few years, promising therapies with the goal to restore CFTR function became available and changed the lives of several CF patients. These medications, called CFTR modulators, aim to correct, potentialize, stabilize or amplify CFTR function. Furthermore, research is ongoing to develop other targeted therapies that could be more efficient and benefit a larger proportion of the CF community. The purpose of this review is to summarize our current knowledge of CF genetics and therapies restoring CFTR function, particularly CFTR modulators and gene therapy.
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Affiliation(s)
- Christelle Bergeron
- Department of Medicine, Respiratory Division, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC J1H 5N4, Canada;
| | - André M. Cantin
- Department of Medicine, Respiratory Division, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC J1H 5N4, Canada;
- Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Respiratory Division, Faculty of Medicine, University of Sherbrooke, 3001, 12e Avenue Nord, Sherbrooke, QC J1H 5N4, Canada
- Correspondence: ; Tel.: +1-819-346-1110 (ext. 14893); Fax: +1-819-564-5377
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Phenotyping Rare CFTR Mutations Reveal Functional Expression Defects Restored by TRIKAFTA TM. J Pers Med 2021; 11:jpm11040301. [PMID: 33920764 PMCID: PMC8071105 DOI: 10.3390/jpm11040301] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/12/2021] [Accepted: 04/13/2021] [Indexed: 12/15/2022] Open
Abstract
The rare Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) mutations, c.1826A > G (H609R) and c.3067_3072delATAGTG (I1023_V1024del), are associated with severe lung disease. Despite the existence of four CFTR targeted therapies, none have been approved for individuals with these mutations because the associated molecular defects were not known. In this study we examined the consequences of these mutations on protein processing and channel function in HEK293 cells. We found that, similar to F508del, H609R and I1023_V1024del-CFTR exhibited reduced protein processing and altered channel function. Because the I1023_V1024del mutation can be linked with the mutation, I148T, we also examined the protein conferred by transfection of a plasmid bearing both mutations. Interestingly, together with I148T, there was no further reduction in channel function exhibited by I1023-V1024del. Both H609R and I1023_V1024del failed to exhibit significant correction of their functional expression with lumacaftor and ivacaftor. In contrast, the triple modulator combination found in TRIKAFTATM, i.e., tezacaftor, elexacaftor and ivacaftor rescued trafficking and function of both of these mutants. These in-vitro findings suggest that patients harbouring H609R or I1023_V1024del, alone or with I148T, may benefit clinically from treatment with TRIKAFTATM.
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