51
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Turner MJ, Luo Y, Thomas DY, Hanrahan JW. The dual phosphodiesterase 3/4 inhibitor RPL554 stimulates rare class III and IV CFTR mutants. Am J Physiol Lung Cell Mol Physiol 2020; 318:L908-L920. [PMID: 32159371 DOI: 10.1152/ajplung.00285.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Over 2,000 mutations have been reported in the cystic fibrosis transmembrane conductance regulator (cftr) gene, many of which cause disease but are rare and have no effective treatment. Thus, there is an unmet need for new, mutation-agnostic therapies for cystic fibrosis (CF). Phosphodiesterase (PDE) inhibitors are one such class of therapeutics that have been shown to elevate intracellular cAMP levels and stimulate CFTR-dependent anion secretion in human airway epithelia; however, the number of people with CF that could be helped by PDE inhibitors remains to be determined. Here we used Fisher rat thyroid (FRT) cells stably transduced with rare human CFTR mutants and studied their responsiveness to the dual phosphodiesterase 3/4 inhibitor RPL554 (Verona Pharma). Through its inhibitory effect on PDE4D, we find that RPL554 can elevate intracellular cAMP leading to a potentiation of forskolin-stimulated current mediated by R334W, T338I, G551D, and S549R mutants of CFTR when used alone or in combination with CFTR modulators. We also were able to reproduce these effects of RPL554 on G551D-CFTR when it was expressed in primary human bronchial epithelial cells, indicating that RPL554 would have stimulatory effects on rare CFTR mutants in human airways and validating FRT cells as a model for PDE inhibitor studies. Furthermore, we provide biochemical evidence that VX-809 causes surprisingly robust correction of several class III and IV CFTR mutants. Together, our findings further support the therapeutic potential of RPL554 for patients with CF with class III/IV mutations and emphasize the potential of PDEs as potential drug targets that could benefit patients with CF.
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Affiliation(s)
- Mark J Turner
- Department of Physiology, McGill University, Montreal, Quebec, Canada.,Cystic Fibrosis Translational Research Centre, McGill University, Montreal, Quebec, Canada
| | - Yishan Luo
- Department of Physiology, McGill University, Montreal, Quebec, Canada.,Cystic Fibrosis Translational Research Centre, McGill University, Montreal, Quebec, Canada
| | - David Y Thomas
- Cystic Fibrosis Translational Research Centre, McGill University, Montreal, Quebec, Canada.,Department of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - John W Hanrahan
- Department of Physiology, McGill University, Montreal, Quebec, Canada.,Cystic Fibrosis Translational Research Centre, McGill University, Montreal, Quebec, Canada
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52
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Kleizen B, Hunt JF, Callebaut I, Hwang TC, Sermet-Gaudelus I, Hafkemeyer S, Sheppard DN. CFTR: New insights into structure and function and implications for modulation by small molecules. J Cyst Fibros 2020; 19 Suppl 1:S19-S24. [DOI: 10.1016/j.jcf.2019.10.021] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/17/2019] [Accepted: 10/18/2019] [Indexed: 12/22/2022]
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53
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Lopes-Pacheco M. CFTR Modulators: The Changing Face of Cystic Fibrosis in the Era of Precision Medicine. Front Pharmacol 2020; 10:1662. [PMID: 32153386 PMCID: PMC7046560 DOI: 10.3389/fphar.2019.01662] [Citation(s) in RCA: 262] [Impact Index Per Article: 65.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 12/19/2019] [Indexed: 12/22/2022] Open
Abstract
Cystic fibrosis (CF) is a lethal inherited disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene, which result in impairment of CFTR mRNA and protein expression, function, stability or a combination of these. Although CF leads to multifaceted clinical manifestations, the respiratory disorder represents the major cause of morbidity and mortality of these patients. The life expectancy of CF patients has substantially lengthened due to early diagnosis and improvements in symptomatic therapeutic regimens. Quality of life remains nevertheless limited, as these individuals are subjected to considerable clinical, psychosocial and economic burdens. Since the discovery of the CFTR gene in 1989, tremendous efforts have been made to develop therapies acting more upstream on the pathogenesis cascade, thereby overcoming the underlying dysfunctions caused by CFTR mutations. In this line, the advances in cell-based high-throughput screenings have been facilitating the fast-tracking of CFTR modulators. These modulator drugs have the ability to enhance or even restore the functional expression of specific CF-causing mutations, and they have been classified into five main groups depending on their effects on CFTR mutations: potentiators, correctors, stabilizers, read-through agents, and amplifiers. To date, four CFTR modulators have reached the market, and these pharmaceutical therapies are transforming patients' lives with short- and long-term improvements in clinical outcomes. Such breakthroughs have paved the way for the development of novel CFTR modulators, which are currently under experimental and clinical investigations. Furthermore, recent insights into the CFTR structure will be useful for the rational design of next-generation modulator drugs. This review aims to provide a summary of recent developments in CFTR-directed therapeutics. Barriers and future directions are also discussed in order to optimize treatment adherence, identify feasible and sustainable solutions for equitable access to these therapies, and continue to expand the pipeline of novel modulators that may result in effective precision medicine for all individuals with CF.
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Affiliation(s)
- Miquéias Lopes-Pacheco
- Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisbon, Lisbon, Portugal
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54
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McCague AF, Raraigh KS, Pellicore MJ, Davis-Marcisak EF, Evans TA, Han ST, Lu Z, Joynt AT, Sharma N, Castellani C, Collaco JM, Corey M, Lewis MH, Penland CM, Rommens JM, Stephenson AL, Sosnay PR, Cutting GR. Correlating Cystic Fibrosis Transmembrane Conductance Regulator Function with Clinical Features to Inform Precision Treatment of Cystic Fibrosis. Am J Respir Crit Care Med 2020; 199:1116-1126. [PMID: 30888834 DOI: 10.1164/rccm.201901-0145oc] [Citation(s) in RCA: 65] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Rationale: The advent of precision treatment for cystic fibrosis using small-molecule therapeutics has created a need to estimate potential clinical improvements attributable to increases in cystic fibrosis transmembrane conductance regulator (CFTR) function. Objectives: To derive CFTR function of a variety of CFTR genotypes and correlate with key clinical features (sweat chloride concentration, pancreatic exocrine status, and lung function) to develop benchmarks for assessing response to CFTR modulators. Methods: CFTR function assigned to 226 unique CFTR genotypes was correlated with the clinical data of 54,671 individuals enrolled in the Clinical and Functional Translation of CFTR (CFTR2) project. Cross-sectional FEV1% predicted measurements were plotted by age at which measurement was obtained. Shifts in sweat chloride concentration and lung function reported in CFTR modulator trials were compared with function-phenotype correlations to assess potential efficacy of therapies. Measurements and Main Results: CFTR genotype function exhibited a logarithmic relationship with each clinical feature. Modest increases in CFTR function related to differing genotypes were associated with clinically relevant improvements in cross-sectional FEV1% predicted over a range of ages (6-82 yr). Therapeutic responses to modulators corresponded closely to predictions from the CFTR2-derived relationship between CFTR genotype function and phenotype. Conclusions: Increasing CFTR function in individuals with severe disease will have a proportionally greater effect on outcomes than similar increases in CFTR function in individuals with mild disease and should reverse a substantial fraction of the disease process. This study provides reference standards for clinical outcomes that may be achieved by increasing CFTR function.
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Affiliation(s)
- Allison F McCague
- 1 McKusick-Nathans Institute of Genetic Medicine, School of Medicine
| | - Karen S Raraigh
- 1 McKusick-Nathans Institute of Genetic Medicine, School of Medicine
| | | | | | - Taylor A Evans
- 1 McKusick-Nathans Institute of Genetic Medicine, School of Medicine
| | - Sangwoo T Han
- 1 McKusick-Nathans Institute of Genetic Medicine, School of Medicine
| | - Zhongzhou Lu
- 1 McKusick-Nathans Institute of Genetic Medicine, School of Medicine
| | - Anya T Joynt
- 1 McKusick-Nathans Institute of Genetic Medicine, School of Medicine
| | - Neeraj Sharma
- 1 McKusick-Nathans Institute of Genetic Medicine, School of Medicine
| | - Carlo Castellani
- 2 Cystic Fibrosis Center, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Joseph M Collaco
- 3 Eudowood Division of Pediatric Respiratory Sciences, School of Medicine
| | | | | | | | - Johanna M Rommens
- 7 Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Anne L Stephenson
- 8 Department of Respirology, Adult Cystic Fibrosis Program, St. Michael's Hospital, Toronto, Ontario, Canada
| | - Patrick R Sosnay
- 9 Pulmonary and Critical Care Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Garry R Cutting
- 1 McKusick-Nathans Institute of Genetic Medicine, School of Medicine
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55
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Towards next generation therapies for cystic fibrosis: Folding, function and pharmacology of CFTR. J Cyst Fibros 2020; 19 Suppl 1:S25-S32. [PMID: 31902693 PMCID: PMC7052731 DOI: 10.1016/j.jcf.2019.12.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 12/16/2019] [Accepted: 12/18/2019] [Indexed: 12/19/2022]
Abstract
The treatment of cystic fibrosis (CF) has been transformed by orally-bioavailable small molecule modulators of the cystic fibrosis transmembrane conductance regulator (CFTR), which restore function to CF mutants. However, CFTR modulators are not available to all people with CF and better modulators are required to prevent disease progression. Here, we review selectively recent advances in CFTR folding, function and pharmacology. We highlight ensemble and single-molecule studies of CFTR folding, which provide new insight into CFTR assembly, its perturbation by CF mutations and rescue by CFTR modulators. We discuss species-dependent differences in the action of the F508del-CFTR mutation on CFTR expression, stability and function, which might influence pharmacological studies of CFTR modulators in CF animal models. Finally, we illuminate the identification of combinations of two CFTR potentiators (termed co-potentiators), which restore therapeutically-relevant levels of CFTR activity to rare CF mutations. Thus, mechanistic studies of CFTR folding, function and pharmacology inform the development of highly effective CFTR modulators.
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56
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Wang C, Zhao P, Sun S, Teckman J, Balch WE. Leveraging Population Genomics for Individualized Correction of the Hallmarks of Alpha-1 Antitrypsin Deficiency. CHRONIC OBSTRUCTIVE PULMONARY DISEASES-JOURNAL OF THE COPD FOUNDATION 2020; 7:224-246. [PMID: 32726074 DOI: 10.15326/jcopdf.7.3.2019.0167] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Deep medicine is rapidly moving towards a high-definition approach for therapeutic management of the patient as an individual given the rapid progress of genome sequencing technologies and machine learning algorithms. While considered a monogenic disease, alpha-1 antitrypsin (AAT) deficiency (AATD) patients present with complex and variable phenotypes we refer to as the "hallmarks of AATD" that involve distinct molecular mechanisms in the liver, plasma and lung tissues, likely due to both coding and non-coding variation as well as genetic and environmental modifiers in different individuals. Herein, we briefly review the current therapeutic strategies for the management of AATD. To embrace genetic diversity in the management of AATD, we provide an overview of the disease phenotypes of AATD patients harboring different AAT variants. Linking genotypic diversity to phenotypic diversity illustrates the potential for sequence-specific regions of AAT protein fold design to play very different roles during nascent synthesis in the liver and/or function in post-liver plasma and lung environments. We illustrate how to manage diversity with recently developed machine learning (ML) approaches that bridge sequence-to-function-to-structure knowledge gaps based on the principle of spatial covariance (SCV). SCV relationships provide a deep understanding of the genotype to phenotype transformation initiated by AAT variation in the population to address the role of genetic and environmental modifiers in the individual. Embracing the complexity of AATD in the population is critical for risk management and therapeutic intervention to generate a high definition medicine approach for the patient.
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Affiliation(s)
- Chao Wang
- Department of Molecular Medicine, Scripps Research, La Jolla, California
| | - Pei Zhao
- Department of Molecular Medicine, Scripps Research, La Jolla, California
| | - Shuhong Sun
- Department of Molecular Medicine, Scripps Research, La Jolla, California
| | - Jeffrey Teckman
- Pediatrics and Biochemistry, Saint Louis University, and Cardinal Glennon Children's Medical Center, St. Louis, Missouri
| | - William E Balch
- Department of Molecular Medicine, Scripps Research, La Jolla, California
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57
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Pallin M, Daley C. Positive clinical outcomes following ivacaftor treatment in a cystic fibrosis patient with the genotype 3272–26A > G/Q493X. J Cyst Fibros 2020; 19:e3-e4. [DOI: 10.1016/j.jcf.2019.11.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 11/14/2019] [Accepted: 11/15/2019] [Indexed: 11/28/2022]
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58
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Park JK, Shrivastava A, Zhang C, Pollok BA, Finkbeiner WE, Gibb ER, Ly NP, Illek B. Functional Profiling of CFTR-Directed Therapeutics Using Pediatric Patient-Derived Nasal Epithelial Cell Models. Front Pediatr 2020; 8:536. [PMID: 33014932 PMCID: PMC7500161 DOI: 10.3389/fped.2020.00536] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 07/27/2020] [Indexed: 12/11/2022] Open
Abstract
Functional profiling of CFTR-directed therapeutics offers the potential to provide significant benefits to young people with cystic fibrosis (CF). However, the development of 2D airway epithelial cell models for individual response tests in CF children remains a central task. The objective of this study was to determine the utility of EpiXTM technology for expansion of nasal epithelial cells for use in electrophysiological CFTR function measurements. An initial harvest of as few as 20,000 cells was sufficient to expand up to 50 million cells that were used to generate air-liquid interface (ALI) cultures for ion transport studies with the Ussing assay. CFTR function was assessed by measuring responses to forskolin and the CFTR potentiator VX-770 (ivacaftor) in ALI cultures generated from passage 3 and 4 cells. Short-circuit current (Isc) measurements of blocked CFTR currents (ΔICFTRinh) discriminated CFTR function between healthy control (wild type, WT) and patients with intermediate (F508del/R117H-7T: 56% WT) and severe (F508del/F508del: 12% WT) CF disease. For the mixed genotypes, CFTR activity for F508del/c.850dupA was 12% WT, R334W/406-1G>A was 24% WT, and CFTRdele2,3(21 kb)/CFTRdele2,3(21 kb) was 9% WT. The CFTR correctors VX-809 (lumacaftor) and VX-661 (tezacaftor) significantly increased CFTR currents for F508del/R117H to 73 and 67% WT, respectively. Cultures with the large deletion mutation CFTRdele2,3(21 kb) unexpectedly responded to VX-661 treatment (20% WT). Amiloride-sensitive sodium currents were robust and ranged between 20-80 μA/cm2 depending on the subject. In addition to characterizing the electrophysiological profile of mutant CFTR activity in cultures for five genotypes, our study exemplifies the promising paradigm of bed-to-bench side cooperation and personalized medicine.
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Affiliation(s)
- Jeffrey KiHyun Park
- UCSF Benioff Children's Hospital Oakland, Children's Hospital Oakland Research Institute, Oakland, CA, United States
| | | | | | | | - Walter E Finkbeiner
- Department of Pathology, UCSF and Zuckerberg San Francisco General Hospital, San Francisco, CA, United States
| | - Elizabeth R Gibb
- Department of Pediatrics, UCSF Benioff Children's Hospital San Francisco, San Francisco, CA, United States
| | - Ngoc P Ly
- Department of Pediatrics, UCSF Benioff Children's Hospital San Francisco, San Francisco, CA, United States
| | - Beate Illek
- UCSF Benioff Children's Hospital Oakland, Children's Hospital Oakland Research Institute, Oakland, CA, United States.,Department of Pediatrics, UCSF Benioff Children's Hospital San Francisco, San Francisco, CA, United States
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59
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Han ST, Cutting GR. Molecular Genetics of Cystic Fibrosis. Respir Med 2020. [DOI: 10.1007/978-3-030-42382-7_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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60
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Sharma N, Cutting GR. The genetics and genomics of cystic fibrosis. J Cyst Fibros 2019; 19 Suppl 1:S5-S9. [PMID: 31879237 DOI: 10.1016/j.jcf.2019.11.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 11/06/2019] [Accepted: 11/08/2019] [Indexed: 02/07/2023]
Abstract
Genetics is the branch of biology concerned with study of individual genes and how they work whereas genomics is involved with the analysis of all genes and their interactions. Both of these approaches have been applied extensively to CF. Identification of the CFTR gene initiated the dissection of CF genetics at the molecular level. Subsequently, thousands of variants were found in the gene and the functional consequences of a subset have been studied in detail. The completion of the human genome ushered in a new phase of study where the role of genes beyond CFTR could be evaluated for their contribution to the severity of CF. This will be a brief overview of the contribution of these complementary methods to our understanding of CF pathogenesis.
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Affiliation(s)
- N Sharma
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - G R Cutting
- Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America.
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61
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Phuan PW, Tan JA, Rivera AA, Zlock L, Nielson DW, Finkbeiner WE, Haggie PM, Verkman AS. Nanomolar-potency 'co-potentiator' therapy for cystic fibrosis caused by a defined subset of minimal function CFTR mutants. Sci Rep 2019; 9:17640. [PMID: 31776420 PMCID: PMC6881293 DOI: 10.1038/s41598-019-54158-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 11/07/2019] [Indexed: 12/11/2022] Open
Abstract
Available CFTR modulators provide no therapeutic benefit for cystic fibrosis (CF) caused by many loss-of-function mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel, including N1303K. We previously introduced the concept of ‘co-potentiators’ (combination-potentiators) to rescue CFTR function in some minimal function CFTR mutants. Herein, a screen of ~120,000 drug-like synthetic small molecules identified active co-potentiators of pyrazoloquinoline, piperidine-pyridoindole, tetrahydroquinoline and phenylazepine classes, with EC50 down to ~300 nM following initial structure-activity studies. Increased CFTR chloride conductance by up to 8-fold was observed when a co-potentiator (termed ‘Class II potentiator’) was used with a classical potentiator (‘Class I potentiator’) such as VX-770 or GLPG1837. To investigate the range of CFTR mutations benefitted by co-potentiators, 14 CF-associated CFTR mutations were studied in transfected cell models. Co-potentiator efficacy was found for CFTR missense, deletion and nonsense mutations in nucleotide binding domain-2 (NBD2), including W1282X, N1303K, c.3700A > G and Q1313X (with corrector for some mutations). In contrast, CFTR mutations G85E, R334W, R347P, V520F, R560T, A561E, M1101K and R1162X showed no co-potentiator activity, even with corrector. Co-potentiator efficacy was confirmed in primary human bronchial epithelial cell cultures generated from a N1303K homozygous CF subject. The Class II potentiators identified here may have clinical benefit for CF caused by mutations in the NBD2 domain of CFTR.
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Affiliation(s)
- Puay-Wah Phuan
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA.
| | - Joseph-Anthony Tan
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Amber A Rivera
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Lorna Zlock
- Department of Pathology, University of California, San Francisco, San Francisco, CA, USA
| | - Dennis W Nielson
- Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA
| | - Walter E Finkbeiner
- Department of Pathology, University of California, San Francisco, San Francisco, CA, USA
| | - Peter M Haggie
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Alan S Verkman
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA.,Department of Physiology, University of California, San Francisco, San Francisco, CA, USA
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62
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Joshi D, Ehrhardt A, Hong JS, Sorscher EJ. Cystic fibrosis precision therapeutics: Emerging considerations. Pediatr Pulmonol 2019; 54 Suppl 3:S13-S17. [PMID: 31715091 PMCID: PMC6871648 DOI: 10.1002/ppul.24547] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 10/08/2019] [Indexed: 11/11/2022]
Abstract
Small molecules that address fundamental defects underlying cystic fibrosis (CF), including modulators such as the approved drugs ivacaftor, lumacaftor, tezacaftor, and elexacaftor, have advanced dramatically over the past few years and are transforming care and prognosis among individuals with this disease. The new treatment strategies are predicated on established scientific insight concerning pathogenesis, and applying "personalized" or "precision" interventions for specific abnormalities of the cystic fibrosis transmembrane conductance regulator (CFTR). Even with the advent of highly effective triple drug combinations-which hold great promise for the majority of patients with CF worldwide-barriers to precision therapy remain. These include refractory CFTR variants (premature truncation codons, splice defects, large indels, severe missense mutations, and others) not addressed by available modulators, and access to leading-edge therapeutic compounds for patients with ultrarare forms of CF. In addition to describing the remarkable progress that has occurred regarding CF precision medicine, this review outlines some of the remaining challenges. The CF experience is emblematic of many conditions for which personalized interventions are actively being sought.
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Affiliation(s)
- D Joshi
- Emory University School of Medicine Department of Pediatrics, and Children’s Healthcare of Atlanta, GA, USA
| | - A Ehrhardt
- Emory University School of Medicine Department of Pediatrics, and Children’s Healthcare of Atlanta, GA, USA
| | - JS Hong
- Emory University School of Medicine Department of Pediatrics, and Children’s Healthcare of Atlanta, GA, USA
| | - EJ Sorscher
- Emory University School of Medicine Department of Pediatrics, and Children’s Healthcare of Atlanta, GA, USA
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63
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Mutation-specific dual potentiators maximize rescue of CFTR gating mutants. J Cyst Fibros 2019; 19:236-244. [PMID: 31678009 DOI: 10.1016/j.jcf.2019.10.011] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 10/04/2019] [Accepted: 10/08/2019] [Indexed: 12/14/2022]
Abstract
BACKGROUND The potentiator ivacaftor (VX-770) has been approved for therapy of 38 cystic fibrosis (CF) mutations (∼10% of the patient population) associated with a gating defect of the CF transmembrane conductance regulator (CFTR). Despite the success of VX-770 treatment of patients carrying at least one allele of the most common gating mutation G551D-CFTR, some lung function decline and P. aeruginosa colonization persist. This study aims at identifying potentiator combinations that can considerably enhance the limited channel activity of a panel of CFTR gating mutants over monotherapy. METHODS The functional response of 13 CFTR mutants to single potentiators or systematic potentiator combinations was determined in the human bronchial epithelial cell line CFBE41o- and a subset of them was confirmed in primary human nasal epithelia (HNE). RESULTS In six out of thirteen CFTR missense mutants the fractional plasma membrane (PM) activity, a surrogate measure of CFTR channel gating, reached only ∼10-50% of WT channel activity upon VX-770 treatment, indicating incomplete gating correction. Combinatorial potentiator profiling and cluster analysis of mutant responses to 24 diverse investigational potentiators identified several compound pairs that improved the gating activity of R352Q-, S549R-, S549N-, G551D-, and G1244E-CFTR to ∼70-120% of the WT. Similarly, the potentiator combinations were able to confer WT-like function to G551D-CFTR in patient-derived human nasal epithelia. CONCLUSION This study suggests that half of CF patients with missense mutations approved for VX-770 administration, could benefit from the development of dual potentiator therapy.
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64
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Chen KG, Zhong P, Zheng W, Beekman JM. Pharmacological analysis of CFTR variants of cystic fibrosis using stem cell-derived organoids. Drug Discov Today 2019; 24:2126-2138. [PMID: 31173911 DOI: 10.1016/j.drudis.2019.05.029] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 05/09/2019] [Accepted: 05/30/2019] [Indexed: 12/29/2022]
Abstract
Cystic fibrosis (CF) is a life-shortening genetic disease caused by mutations of CFTR, the gene encoding cystic fibrosis transmembrane conductance regulator. Despite considerable progress in CF therapies, targeting specific CFTR genotypes based on small molecules has been hindered because of the substantial genetic heterogeneity of CFTR mutations in patients with CF, which is difficult to assess by animal models in vivo. There are broadly four classes (e.g., II, III, and IV) of CF genotypes that differentially respond to current CF drugs (e.g., VX-770 and VX-809). In this review, we shed light on the pharmacogenomics of diverse CFTR mutations and the emerging role of stem cell-based organoids in predicting the CF drug response. We discuss mechanisms that underlie differential CF drug responses both in organoid-based assays and in CF clinical trials, thereby facilitating the precision design of safer and more effective therapies for individual patients with CF.
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Affiliation(s)
- Kevin G Chen
- NIH Stem Cell Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA; Department of Microbiology and Immunology, Georgetown University Medical Center, Washington DC, 20057, USA.
| | - Pingyu Zhong
- Singapore Immunology Network, Agency for Science, Technology and Research (A⁎STAR), 8A Biomedical Grove, Singapore 138648, Singapore
| | - Wei Zheng
- National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jeffrey M Beekman
- Department of Pediatric Pulmonology, Wilhelmina Children's Hospital, Regenerative Medicine Center Utrecht, University Medical Center, Utrecht University, Utrecht, The Netherlands
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65
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Aksit MA, Bowling AD, Evans TA, Joynt AT, Osorio D, Patel S, West N, Merlo C, Sosnay PR, Cutting GR, Sharma N. Decreased mRNA and protein stability of W1282X limits response to modulator therapy. J Cyst Fibros 2019; 18:606-613. [PMID: 30803905 DOI: 10.1016/j.jcf.2019.02.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 02/14/2019] [Accepted: 02/14/2019] [Indexed: 12/13/2022]
Abstract
BACKGROUND Cell-based studies have shown that W1282X generates a truncated protein that can be functionally augmented by modulators. However, modulator treatment of primary cells from individuals who carry two copies of W1282X generates no functional CFTR. To understand the lack of response to modulators, we investigated the effect of W1282X on CFTR RNA transcript levels. METHODS qRT-PCR and RNA-seq were performed on primary nasal epithelial (NE) cells of a previously studied individual who is homozygous for W1282X, her carrier parents and control individuals without nonsense variants in CFTR. RESULTS CFTR RNA bearing W1282X in NE cells shows a steady-state level of 4.2 ± 0.9% of wild-type (WT) CFTR RNA in the mother and 12.4 ± 1.3% in the father. NMDI14, an inhibitor of nonsense-mediated mRNA decay (NMD), restored W1282X mRNA to almost 50% of WT levels in the parental NE cells. RNA-seq of the NE cells homozygous for W1282X showed that CFTR transcript level was reduced to 1.7% of WT (p-value: 4.6e-3). Negligible truncated CFTR protein was generated by Flp-In 293 cells stably expressing the W1282X EMG even though CFTR transcript was well above levels observed in the parents and proband. Finally, we demonstrated that NMD inhibition improved the stability and response to correctors of W1282X-CFTR protein expressed in the Flp-In-293 cells. CONCLUSION These results show that W1282X can cause substantial degradation of CFTR mRNA that has to be addressed before efforts aimed at augmenting CFTR protein function can be effective.
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Affiliation(s)
- M A Aksit
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - A D Bowling
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - T A Evans
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - A T Joynt
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - D Osorio
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - S Patel
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins Hospital, Baltimore, MD, United States
| | - N West
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins Hospital, Baltimore, MD, United States
| | - C Merlo
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins Hospital, Baltimore, MD, United States
| | - P R Sosnay
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins Hospital, Baltimore, MD, United States
| | - G R Cutting
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - N Sharma
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States.
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Foil KE, Powers A, Raraigh KS, Wallis K, Southern KW, Salinas D. The increasing challenge of genetic counseling for cystic fibrosis. J Cyst Fibros 2018; 18:167-174. [PMID: 30527892 DOI: 10.1016/j.jcf.2018.11.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Revised: 10/30/2018] [Accepted: 11/26/2018] [Indexed: 12/12/2022]
Abstract
Genetic counseling for cystic fibrosis (CF) is challenged by intricate molecular mechanisms, complex phenotypes, and psychosocial needs. CFTR variant interpretation has become critical; this manuscript examines variant nomenclature and classes, as well as opportunities and challenges posed by genetic technologies and genotype-directed therapies. With post-graduate training in medical genetics and counseling, genetic counselors educate patients and families, facilitate testing and interpretation, and help integrate genetic information into diagnosis and treatment. They support families, ranging from carrier couples or new parents, to children understanding their disease, to adults with CF contemplating reproduction. The changing face of CF increasingly highlights the critical importance of genetic information to patients and their families. Genetic counselors are uniquely poised to translate this information in diagnostics and personalized care. Genetic counselors straddle molecular and clinical realms, helping patients adapt, plan, and gain access to appropriate therapies.
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Affiliation(s)
- Kimberly E Foil
- Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, Medical University of South Carolina, Charleston, SC, 29425, United States.
| | - Amy Powers
- Division of Pediatric Pulmonary and Sleep Medicine, University of Minnesota Health, Minneapolis, MN, 55455, United States.
| | - Karen S Raraigh
- Institute of Genetic Medicine, Johns Hopkins University, Baltimore, MD 21287, United States.
| | - Kimberly Wallis
- Center for Human Genetics, University Hospitals Cleveland Medical Center, Cleveland, OH 44106, Kimberly, United States.
| | - Kevin W Southern
- Department of Women's and Children's Health, Alder Hey Children's Hospital, University of Liverpool, Liverpool, England L12 2AP, United Kingdom.
| | - Danieli Salinas
- Children's Hospital Los Angeles, Pediatric Pulmonology Division, Department of Pediatrics, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, United States.
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Sharma N, Evans TA, Pellicore MJ, Davis E, Aksit MA, McCague AF, Joynt AT, Lu Z, Han ST, Anzmann AF, Lam ATN, Thaxton A, West N, Merlo C, Gottschalk LB, Raraigh KS, Sosnay PR, Cotton CU, Cutting GR. Capitalizing on the heterogeneous effects of CFTR nonsense and frameshift variants to inform therapeutic strategy for cystic fibrosis. PLoS Genet 2018; 14:e1007723. [PMID: 30444886 PMCID: PMC6267994 DOI: 10.1371/journal.pgen.1007723] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 11/30/2018] [Accepted: 09/28/2018] [Indexed: 12/18/2022] Open
Abstract
CFTR modulators have revolutionized the treatment of individuals with cystic fibrosis (CF) by improving the function of existing protein. Unfortunately, almost half of the disease-causing variants in CFTR are predicted to introduce premature termination codons (PTC) thereby causing absence of full-length CFTR protein. We hypothesized that a subset of nonsense and frameshift variants in CFTR allow expression of truncated protein that might respond to FDA-approved CFTR modulators. To address this concept, we selected 26 PTC-generating variants from four regions of CFTR and determined their consequences on CFTR mRNA, protein and function using intron-containing minigenes expressed in 3 cell lines (HEK293, MDCK and CFBE41o-) and patient-derived conditionally reprogrammed primary nasal epithelial cells. The PTC-generating variants fell into five groups based on RNA and protein effects. Group A (reduced mRNA, immature (core glycosylated) protein, function <1% (n = 5)) and Group B (normal mRNA, immature protein, function <1% (n = 10)) variants were unresponsive to modulator treatment. However, Group C (normal mRNA, mature (fully glycosylated) protein, function >1% (n = 5)), Group D (reduced mRNA, mature protein, function >1% (n = 5)) and Group E (aberrant RNA splicing, mature protein, function > 1% (n = 1)) variants responded to modulators. Increasing mRNA level by inhibition of NMD led to a significant amplification of modulator effect upon a Group D variant while response of a Group A variant was unaltered. Our work shows that PTC-generating variants should not be generalized as genetic 'nulls' as some may allow generation of protein that can be targeted to achieve clinical benefit.
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Affiliation(s)
- Neeraj Sharma
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Taylor A. Evans
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Matthew J. Pellicore
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Emily Davis
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Melis A. Aksit
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Allison F. McCague
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Anya T. Joynt
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Zhongzhu Lu
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Sangwoo T. Han
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Arianna F. Anzmann
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Anh-Thu N. Lam
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Abigail Thaxton
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins Hospital, Baltimore, Maryland, United States of America
| | - Natalie West
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins Hospital, Baltimore, Maryland, United States of America
| | - Christian Merlo
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins Hospital, Baltimore, Maryland, United States of America
| | - Laura B. Gottschalk
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Karen S. Raraigh
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Patrick R. Sosnay
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins Hospital, Baltimore, Maryland, United States of America
| | - Calvin U. Cotton
- Departments of Pediatrics, Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Garry R. Cutting
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
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Wang Y, Cai Z, Gosling M, Sheppard DN. Potentiation of the cystic fibrosis transmembrane conductance regulator Cl− channel by ivacaftor is temperature independent. Am J Physiol Lung Cell Mol Physiol 2018; 315:L846-L857. [DOI: 10.1152/ajplung.00235.2018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Ivacaftor is the first drug to target directly defects in the cystic fibrosis transmembrane conductance regulator (CFTR), which causes cystic fibrosis (CF). To understand better how ivacaftor potentiates CFTR channel gating, here we investigated the effects of temperature on its action. As a control, we studied the benzimidazolone UCCF-853, which potentiates CFTR by a different mechanism. Using the patch-clamp technique and cells expressing recombinant CFTR, we studied the single-channel behavior of wild-type and F508del-CFTR, the most common CF mutation. Raising the temperature of the intracellular solution from 23 to 37°C increased the frequency but reduced the duration of wild-type and F508del-CFTR channel openings. Although the open probability ( Po) of wild-type CFTR increased progressively as temperature was elevated, the relationship between Po and temperature for F508del-CFTR was bell-shaped with a maximum Po at ~30°C. For wild-type CFTR and to a greatly reduced extent F508del-CFTR, the temperature dependence of channel gating was asymmetric with the opening rate demonstrating greater temperature sensitivity than the closing rate. At all temperatures tested, ivacaftor and UCCF-853 potentiated wild-type and F508del-CFTR. Strikingly, ivacaftor but not UCCF-853 abolished the asymmetric temperature dependence of CFTR channel gating. At all temperatures tested, Po values of wild-type CFTR in the presence of ivacaftor were approximately double those of F508del-CFTR, which were equivalent to or greater than those of wild-type CFTR at 37°C in the absence of the drug. We conclude that the principal effect of ivacaftor is to promote channel opening to abolish the temperature dependence of CFTR channel gating.
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Affiliation(s)
- Yiting Wang
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, United Kingdom
| | - Zhiwei Cai
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, United Kingdom
| | - Martin Gosling
- Enterprise Therapeutics, Sussex Innovation Centre, University of Sussex, Science Park Square, Brighton, United Kingdom
- Sussex Drug Discovery Centre, School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - David N. Sheppard
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol, United Kingdom
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Noel S, Sermet-Gaudelus I, Sheppard DN. N1303K: Leaving no stone unturned in the search for transformational therapeutics. J Cyst Fibros 2018; 17:555-557. [PMID: 30126793 DOI: 10.1016/j.jcf.2018.07.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Sabrina Noel
- INSERM U1151, Institut Necker Enfants Malades, Paris, France; Université Paris Descartes, Paris, France
| | - Isabelle Sermet-Gaudelus
- INSERM U1151, Institut Necker Enfants Malades, Paris, France; Université Paris Descartes, Paris, France
| | - David N Sheppard
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom.
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