Additional general modulator references from 2020 onwards

Lopes-Pacheco M.  CFTR Modulators: The Changing Face of Cystic Fibrosis in the Era of Precision Medicine, Front Pharmacol.  2020 Feb 21;10:1662. doi: 10.3389/fphar.2019.01662. eCollection 2019. [Pubmed]  (Full version on internet)

Miquela Lopes-Pacheco

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.

Dr Miqueias Lopes-Pacheco is at Biosystems & Integrative Sciences Institute, Faculty of Sciences, University of Lisbon, Lisbon, Portugal.

– This is a very detailed extensively referenced account of the present situation concerning modulators. The full text is available and can be recommended.

Egan ME.  Emerging Technologies for Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Restoration in all People with CF.   Pediatr Pulmonol. 2020 Jul 18. doi: 10.1002/ppul.24965. Online ahead of print.[Pubmed]

          Mary Egan

These therapies optimize the function of the patients’ endogenous mutant Cystic FibrosisTransmembrane Conductance Regulator (CFTR), which results in return of CFTR channel function. 2019 will be remembered as a landmark year for the Cystic Fibrosis (CF) community because it marks the year when effective modulator therapy became available for most CF patients. It is unlikely that this approach will provide a game changing therapy for all. In part because the response to even the most promising modulator therapy is variable and an area of active investigation. Also, there are about 10% of patients with CF who don’t produce a mutant protein to modulate, potentiate or optimize and for these patients such therapies are unlikely to be of significant benefit. Efforts to develop small molecule therapy to promote protein production in patients with nonsense mutations such as PTC124 has proved to be far more challenging than predicted.

There is a need to develop new therapeutic approaches that can work for this patient population. These new therapies will be genetic-based therapies that include ribonucleic acid (RNA) therapies, deoxyribonucleic acid (DNA) therapies and gene editing technologies. Each approach will result in functional CFTR expression in CF affected cells. Ideally, these approaches would require less frequent dosing than effective modulators, which are given daily. For instance, RNA based treatments could be given periodically.

Ultimately, treatment with certain gene-altering treatments could be given once in a lifetime and lead to a permanent cure.  In this review which is based on Plenary 1 from the North American Cystic Fibrosis Conference in 2019 which is based on Plenary 1 from the North American Cystic Fibrosis Conference in 2019 the potential of RNA therapies, gene transfer therapies and gene editing therapies for the treatment of CF are reviewed, as well as the challenges that will need to be faced as we harness the power of these emerging therapies towards a one-time cure.

 Dr Marie E Egan is  Professor of Pediatrics (Respiratory) and of Cellular and Molecular Physiology; Director Cystic fibrosis Center and Vice Chair of Research Pediatrics, School of Medicine, Yale University, New Haven, CT, USA.

Geraint B RogersSteven L TaylorLucas R HoffmanLucy D Burr.   The impact of CFTR modulator therapies on CF airway microbiology.   J Cyst Fibros 2020 May;19(3):359-364. doi: 10.1016/j.jcf.2019.07.008.Epub 2019 Aug[Pubmed]

         Geraint Rodgers

Major historical advances in cystic fibrosis (CF) respiratory clinical care, including mechanical airway clearance and inhaled medications, have aimed to address the consequences of cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction. In contrast, CFTR modulator therapies instead target the underlying protein defect that leads to CF lung disease. The extent to which these therapies might reduce susceptibility to chronic lung infections remains to be seen. However, by improving airway clearance, reducing the requirement for antibiotics, and in some cases, through direct antimicrobial effects, CFTR modulators are likely to result in substantial changes in CF airway microbiology. These changes could contribute substantially to the clinical benefit associated with modulator therapies, as well as providing an important indicator of treatment efficacy and residual pathophysiology. Indeed, the widespread introduction of modulator therapies might require us to re-consider our models of CF airway microbiology.

Prof Geraint B Rogers is a molecular microbiologist and microbial ecologist. He is the Director, Microbiome Research at SAHMRI, leads a laboratory based within the Flinders University School of Medicine, Adelaide

Koliarne TongDaniel BarkerMegan FranceLucy BurrHugh GrevilleSimone VisserPeter MiddletonClaire WainwrightDouglas DorahyPeter Wark.  Lumacaftor/ivacaftor reduces exacerbations in adults homozygous for Phe508del mutation with severe lung disease.  J Cyst Fibros   2020 May;19(3):415-420.doi: 10.1016/j.jcf.2019.12.006. Epub 2019 Dec 15.[Pubmed]

Peter Wark

       Koliarne Tong

Background: Lumacaftor/ivacaftor (LUM/IVA) improves outcomes in cystic fibrosis (CF) patients homozygous for Phe508del with ppFEV1 > 40%. There is limited safety or efficacy data in patients with ppFEV1 < 40%. We determined whether LUM/IVA in patients with ppFEV1 < 40 would reduce the rate of pulmonary exacerbations.
Methods: This was a case control study performed on patients > 12 years, homozygous for Phe508del CFTR mutation and with ppFEV1 < 40%. Control subjects were matched for age, sex and ppFEV1, and had mutations ineligible for LUM/IVA. We assessed the rate of pulmonary exacerbations requiring intravenous antibiotics, the mean rate of change in ppFEV1 over 12 months and all adverse events.
Results: Data was collected from 7 Australian CF centres on 105 patients; 72 on LUM/IVA and 33 controls. LUM/IVA demonstrated a large reduction in exacerbations with an incident rate ratio of 0.455 (95%CI; 0.306 – 0.676), p < 0.001 after adjusting for the number of exacerbations in the previous 12 months. LUM/IVA prolonged the time to first exacerbation and reduced the rate of decline in ppFEV1 over 12 months. Adverse events were common; chest tightness or dyspnoea was experienced by 55% and resulted in cessation of treatment in 32%.
Conclusions: Treatment with LUM/IVA resulted in a substantially lower rate of pulmonary exacerbations, prolonged time to first exacerbation and slowed the rate of decline of ppFEV1 in participants with severe lung disease. Adverse reactions to LUM/IVA however were unacceptably frequent and resulted in a very high discontinuation rate.

Dr Koliarne Tong is Staff Specialist in Respiratory and Sleep at the Adult Cystic Fibrosis Centre, John Hunter Hospital, Australia.

Professor Peter Wark, the corresponding author, a senior staff specialist in Respiratory and Sleep Medicine at John Hunter Hospital, Newcastle and a conjoint Professor with the University of Newcastle

Tétard C, Mittaine M, Bui S, Beaufils F, Maumus P, Fayon M, Burgel PR, Lamireau T, Delhaes L, Mas E, Enaud R. Reduced Intestinal Inflammation with Lumacaftor/Ivacaftor in Adolescents with Cystic Fibrosis.  J Pediatr Gastroenterol Nutr. 2020 Jul 30. doi: 10.1097/MPG.0000000000002864. Online ahead of print. [Pubmed]
A chronic intestinal inflammation may occur in patients with cystic fibrosis (CF), while no therapeutic management is proposed. While Lumacaftor/Ivacaftor is well-known to modulate the defective cystic fibrosis transmembrane conductance regulator (CFTR) protein in lungs, no data are available on the impact of this treatment on CF intestinal disorders. The authors therefore investigated the evolution of intestinal inflammation after initiation of Lumacaftor/Ivacaftor in CF adolescents (median of follow-up: 336 days (IQR: 278;435)). Median fecal calprotectin concentrations decreased significantly after Lumacaftor/Ivacaftor initiation (102 μg/g (IQR: 69;210)) compared to the baseline (713 μg/g (IQR:148;852), p = 0.001).

To their knowledge, this study showed for the first time that CF-related intestinal inflammation is improved by Lumacaftor/Ivacaftor treatment.

From Centre Hospitalier Universitaire de Bordeaux, CHU Bordeaux, CRCM Pédiatrique, Bordeaux, France.

Tétard C, Mittaine M, Bui S, Beaufils F, Maumus P, Fayon M, Burgel PR, Lamireau T, Delhaes L, Mas E, Enaud R.Reduced Intestinal Inflammation with Lumacaftor/Ivacaftor in Adolescents with Cystic Fibrosis.  J Pediatr Gastroenterol Nutr. 2020 Jul 30. doi: 10.1097/MPG.0000000000002864. Online ahead of print. [Pubmed]
A chronic intestinal inflammation may occur in patients with cystic fibrosis (CF), while no therapeutic management is proposed. While Lumacaftor/Ivacaftor is well-known to modulate the defective cystic fibrosis transmembrane conductance regulator (CFTR) protein in lungs, no data are available on the impact of this treatment on CF intestinal disorders. The authors therefore investigated the evolution of intestinal inflammation after initiation of Lumacaftor/Ivacaftor in CF adolescents (median of follow-up: 336 days (IQR: 278;435)). Median fecal calprotectin concentrations decreased significantly after Lumacaftor/Ivacaftor initiation (102 μg/g (IQR: 69;210)) compared to the baseline (713 μg/g (IQR:148;852), p = 0.001).

To their knowledge, this study showed for the first time that CF-related intestinal inflammation is improved by Lumacaftor/Ivacaftor treatment.

From Centre Hospitalier Universitaire de Bordeaux, CHU Bordeaux, CRCM Pédiatrique, Bordeaux, France.

Marcus A Mall ENaC inhibition in cystic fibrosis: potential role in the new era of CFTR modulator therapies.  Eur Respir J 2020 Jul 30;2000946.doi: 10.1183/13993003.00946-2020.Online ahead of print [Pubmed]

     Marcus A Mall

Cystic fibrosis transmembrane conductance regulator (CFTR) modulators are the first approved drugs targeting underlying epithelial ion/fluid transport defects in patients with cystic fibrosis (CF). Current CFTR modulators restore mutant CFTR activity to up to ∼50% of normal CFTR Cl channel function, translating into improvements in percentage predicted FEV1 and other clinical outcomes. In addition, reductions in airway bacterial colonisation are observed; however, patients fail to eradicate bacteria over time and still experience pulmonary exacerbations, and long-term safety of CFTR modulator therapy remains unknown. Currently approved CFTR modulators are predicted to be effective for up to 90% of patients. A mutation-agnostic approach could address the remaining 10% with CFTR mutations unresponsive to CFTR modulator therapy and may act together with CFTR modulator therapy to further improve epithelial ion/fluid transport and clinical outcomes. Together with CFTR and other Cl channels, the epithelial Na+ channel (ENaC) is key to regulating airway surface liquid homeostasis. ENaC activity is limiting for Na+/fluid absorption and remains intact or may even be increased in CF airways, leading to increased Na+/fluid absorption, airway surface dehydration, impaired mucociliary clearance, bacterial infection, inflammation and progressive lung damage – the major cause of CF-related morbidity and mortality. Inhibition of ENaC in the airways is therefore an attractive therapeutic target to counteract airway surface dehydration and downstream consequences in CF lung disease. This review examines ENaC inhibition in CF therapy, and describes a new ENaC inhibitor with potential mutation-agnostic therapeutic benefit, both alone, and in synergy with CFTR modulators.

Professor Marcus Mall is at Department of Pediatric Pulmonology, Immunology and Critical Care Medicine, Charité – Universitätsmedizin Berlin,  Berlin Institute of Health and the  German Center for Lung Research (DZL), associated partner site, Berlin