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Lin WY, Sohma Y, Hwang TC. Synergistic Potentiation of Cystic Fibrosis Transmembrane Conductance Regulator Gating by Two Chemically Distinct Potentiators, Ivacaftor (VX-770) and 5-Nitro-2-(3-Phenylpropylamino) Benzoate. Mol Pharmacol 2016; 90:275-85. [PMID: 27413118 PMCID: PMC4998663 DOI: 10.1124/mol.116.104570] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 07/12/2016] [Indexed: 01/12/2023] Open
Abstract
Cystic fibrosis (CF) is caused by loss-of-function mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene encoding a phosphorylation-activated but ATP-gated chloride channel. Previous studies suggested that VX-770 [ivacaftor, N-(2,4-di-tert-butyl-5-hydroxyphenyl)-4-oxo-1,4-dihydroquinoline-3-carboxamide], a CFTR potentiator now used in clinics, increases the open probability of CFTR by shifting the gating conformational changes to favor the open channel configuration. Recently the chloride channel blocker and CFTR potentiator 5-nitro-2-(3-phenylpropylamino) benzoate (NPPB) has been reported to enhance CFTR activity by a mechanism that exploits the ATP hydrolysis-driven, nonequilibrium gating mechanism unique to CFTR. Surprisingly however, NPPB increased the activity of nonhydrolytic G551D-CFTR, the third most common disease-associated mutation. Here, we further investigated the mechanism of NPPB's effects on CFTR gating by assessing its interaction with well-studied VX-770. Interestingly, once G551D-CFTR was maximally potentiated by VX-770, NPPB further increased its activity. However, quantitative analysis of this drug-drug interaction suggests that this pharmacologic synergism is not due to independent actions of NPPB and VX-770 on CFTR gating; instead, our data support a dependent mechanism involving two distinct binding sites. This latter idea is further supported by the observation that the locked-open time of a hydrolysis-deficient mutant K1250A was shortened by NPPB but prolonged by VX-770. In addition, the effectiveness of NPPB, but not of VX-770, was greatly diminished in a mutant whose second nucleotide-binding domain was completely removed. Interpreting these results under the framework of current understanding of CFTR gating not only reveals insights into the mechanism of action for different CFTR potentiators but also brings us one step forward to a more complete schematic for CFTR gating.
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Affiliation(s)
- Wen-Ying Lin
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (W.-Y.L., T.-C.H.); Department of Pharmacology, School of Medicine, Keio University, Tokyo Japan (Y.S.)
| | - Yoshiro Sohma
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (W.-Y.L., T.-C.H.); Department of Pharmacology, School of Medicine, Keio University, Tokyo Japan (Y.S.)
| | - Tzyh-Chang Hwang
- Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri (W.-Y.L., T.-C.H.); Department of Pharmacology, School of Medicine, Keio University, Tokyo Japan (Y.S.)
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Cholon DM, Esther CR, Gentzsch M. Efficacy of lumacaftor-ivacaftor for the treatment of cystic fibrosis patients homozygous for the F508del-CFTR mutation. EXPERT REVIEW OF PRECISION MEDICINE AND DRUG DEVELOPMENT 2016; 1:235-243. [PMID: 27482545 DOI: 10.1080/23808993.2016.1175299] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cystic fibrosis (CF) results from mutations in the CF transmembrane conductance regulator (CFTR) gene, which codes for the CFTR channel protein. The most common mutation in CF is F508del, which produces a misfolded protein with diminished channel activity. The development of small-molecule CFTR-modulator compounds offers an exciting and novel approach for pharmacological treatment of CF. The corrector lumacaftor helps rescue F508del-CFTR to the cell surface, and potentiator ivacaftor increases F508del-CFTR channel activity. The combination of lumacaftor-ivacaftor (Vertex Pharmaceuticals Incorporated) represents the first FDA-approved therapy for CF patients with two copies of the F508del mutation. Although this combination therapy is the first treatment to directly target the F508del-CFTR mutation, patients taking this drug displayed only modest improvements in lung function. This article summarizes recent data from clinical trials and research discoveries relating to the lumacaftor-ivacaftor treatment, and considers options for identifying future therapies that will be most efficacious for all CF patients.
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Affiliation(s)
- Deborah M Cholon
- Marsico Lung Institute/Cystic Fibrosis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Charles R Esther
- Marsico Lung Institute/Cystic Fibrosis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Division of Pediatric Pulmonology, Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Martina Gentzsch
- Marsico Lung Institute/Cystic Fibrosis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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Dhooghe B, Haaf JB, Noel S, Leal T. Strategies in early clinical development for the treatment of basic defects of cystic fibrosis. Expert Opin Investig Drugs 2016; 25:423-36. [PMID: 26878157 DOI: 10.1517/13543784.2016.1154041] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
INTRODUCTION Twenty-six years after the identification of the gene responsible for cystic fibrosis (CF), controversies still surround the pathogenesis of the disease that continues to burden and shorten lives. Therefore, finding effective therapeutic strategies that target the basic defect of CF is crucially needed. AREAS COVERED This review offers a comprehensive survey of fundamental therapies in early stages of development for the treatment of CF. The first part describes recent strategies targeting the basic defect either at the gene or at the transcript level. The second part summarizes a panel of novel strategies targeting protein repair. The third part reports strategies targeting non-CFTR channels. EXPERT OPINION Recent major breakthroughs in CF therapy have been made, raising hope to find a cure for CF. Apart from Vertex corrector and potentiator molecules (lumacaftor, ivacaftor, VX-661) and from ataluren, used to correct nonsense mutations, most compounds being currently tested are in very early (I-II) phases of development and definitive clinical results are keenly expected. Among the broad list of molecules and strategies being tested, the QR-010 compound and inhibitors of phosphodiesterase type 5 (sildenafil, vardenafil) could reveal a strong potentiality as therapeutic candidates to cure CF.
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Affiliation(s)
- Barbara Dhooghe
- a Louvain centre for Toxicology and Applied Pharmacology , Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain , Brussels , Belgium
| | - Jérémy Boris Haaf
- a Louvain centre for Toxicology and Applied Pharmacology , Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain , Brussels , Belgium
| | - Sabrina Noel
- a Louvain centre for Toxicology and Applied Pharmacology , Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain , Brussels , Belgium
| | - Teresinha Leal
- a Louvain centre for Toxicology and Applied Pharmacology , Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain , Brussels , Belgium
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Matthes E, Goepp J, Carlile GW, Luo Y, Dejgaard K, Billet A, Robert R, Thomas DY, Hanrahan JW. Low free drug concentration prevents inhibition of F508del CFTR functional expression by the potentiator VX-770 (ivacaftor). Br J Pharmacol 2016; 173:459-70. [PMID: 26492939 DOI: 10.1111/bph.13365] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 07/22/2015] [Accepted: 10/12/2015] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND AND PURPOSE The most common cystic fibrosis (CF) mutation F508del inhibits the gating and surface expression of CFTR, a plasma membrane anion channel. Optimal pharmacotherapies will probably require both a 'potentiator' to increase channel open probability and a 'corrector' that improves folding and trafficking of the mutant protein and its stability at the cell surface. Interaction between CF drugs has been reported but remains poorly understood. EXPERIMENTAL APPROACH CF bronchial epithelial cells were exposed to the corrector VX-809 (lumacaftor) and potentiator VX-770 (ivacaftor) individually or in combination. Functional expression of CFTR was assayed as the forskolin-stimulated short-circuit current (Isc ) across airway epithelial monolayers expressing F508del CFTR. KEY RESULTS The potentiated Isc response during forskolin stimulation was increased sixfold after pretreatment with VX-809 alone and reached ~11% that measured across non-CF monolayers. VX-770 (100 nM) and genistein (50 μM) caused similar levels of potentiation, which were not additive and were abolished by the CFTR inhibitor CFTRinh -172. The unbound fraction of VX-770 in plasma was 0.13 ± 0.04%, which together with previous measurements in patients given 250 mg p.o. twice daily, suggests a peak free plasma concentration of 1.5-8.5 nM. Chronic exposure to high VX-770 concentrations (>1 μM) inhibited functional correction by VX-809 but not in the presence of physiological protein levels (20-40 mg·mL(-1) ). Chronic exposure to a low concentration of VX-770 (100 nM) together with VX-809 (1 μM) also did not reduce the forskolin-stimulated Isc , relative to cells chronically exposed to VX-809 alone, provided it was assayed acutely using the same, clinically relevant concentration of potentiator. CONCLUSIONS AND IMPLICATIONS Chronic exposure to clinically relevant concentrations of VX-770 did not reduce F508del CFTR function. Therapeutic benefit of VX-770 + VX-809 (Orkambi) is probably limited by the efficacy of VX-809 rather than by inhibition by VX-770.
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Affiliation(s)
- Elizabeth Matthes
- Department of Physiology, McGill University, Montréal, QC, Canada.,CF Translational Research Centre, McGill University, Montréal, QC, Canada
| | - Julie Goepp
- Department of Physiology, McGill University, Montréal, QC, Canada.,CF Translational Research Centre, McGill University, Montréal, QC, Canada
| | - Graeme W Carlile
- CF Translational Research Centre, McGill University, Montréal, QC, Canada.,Department of Biochemistry, McGill University, Montréal, QC, Canada
| | - Yishan Luo
- Department of Physiology, McGill University, Montréal, QC, Canada.,CF Translational Research Centre, McGill University, Montréal, QC, Canada
| | - Kurt Dejgaard
- Department of Biochemistry, McGill University, Montréal, QC, Canada
| | - Arnaud Billet
- Department of Physiology, McGill University, Montréal, QC, Canada.,CF Translational Research Centre, McGill University, Montréal, QC, Canada
| | - Renaud Robert
- Department of Physiology, McGill University, Montréal, QC, Canada.,CF Translational Research Centre, McGill University, Montréal, QC, Canada
| | - David Y Thomas
- CF Translational Research Centre, McGill University, Montréal, QC, Canada.,Department of Biochemistry, McGill University, Montréal, QC, Canada
| | - John W Hanrahan
- Department of Physiology, McGill University, Montréal, QC, Canada.,CF Translational Research Centre, McGill University, Montréal, QC, Canada.,Research Institute of the McGill University Health Centre, Montréal, QC, Canada
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