Furin as a therapeutic target in cystic fibrosis airways disease.

Clinical management of cystic fibrosis (CF) has been greatly improved by the development of small molecule modulators of the CF transmembrane conductance regulator (CFTR). These drugs help to address some of the basic genetic defects of CFTR; however, no suitable CFTR modulators exist for 10% of people with CF (PWCF). An alternative, mutation-agnostic therapeutic approach is therefore still required. In CF airways, elevated levels of the proprotein convertase furin contribute to the dysregulation of key processes that drive disease pathogenesis. Furin plays a critical role in the proteolytic activation of the epithelial sodium channel; hyperactivity of which causes airways dehydration and loss of effective mucociliary clearance. Furin is also responsible for the processing of transforming growth factor-ß, which is increased in bronchoalveolar lavage fluid from PWCF and is associated with neutrophilic inflammation and reduced pulmonary function. Pathogenic substrates of furin include Pseudomonas exotoxin A, a major toxic product associated with Pseudomonas aeruginosa infection and the spike glycoprotein of severe acute respiratory syndrome coronavirus 2, the causative pathogen for coronavirus disease 2019. In this review we discuss the importance of furin substrates in the progression of CF airways disease and highlight selective furin inhibition as a therapeutic strategy to provide clinical benefit to all PWCF.

Impact of elexacaftor/tezacaftor/ivacaftor on depression and anxiety in cystic fibrosis.

BACKGROUND: Cystic fibrosis (CF) is associated with worsening of depression and anxiety symptoms. Elexacaftor/tezacaftor/ivacaftor (Trikafta®), a cystic fibrosis transmembrane regulator (CFTR) modulator approved in 2019, significantly improves lung function, decreases pulmonary exacerbations, and improves quality of life. Studies are needed to evaluate the effects of Trikafta on symptoms of anxiety and depression. RESEARCH QUESTION: Do adults with CF report a change in depression and anxiety symptoms after Trikafta initiation? STUDY DESIGN AND METHODS: A retrospective chart review was conducted of patients with CF (n = 127) receiving care from January 2015 through February 2022. Data collected included demographics, annual PHQ-9 and GAD-7 scores, FEV1 percent predicted at each visit, BMI, consistency and timeline of Trikafta use, mental health diagnoses, counseling/psychotherapy use, psychiatric medication use, prescriber of psychiatric medications, number of psychiatric emergency department visits and psychiatric hospital admissions, and sleep disturbances. RESULTS: Of the 127 patients screened for eligibility, 100 patients were included. Data collected yielded 563 PHQ-9, 563 GAD-7, and 560 ppFEV1 data points. No significant changes in average PHQ-9 or GAD-7 scores were found after Trikafta initiation or due to the COVID-19 pandemic. However, 22% of patients initiated or had a change in psychiatric medications, and patients with changes in psychiatric medications had significantly higher PHQ-9 and GAD-7 scores than patients not prescribed psychiatric medications. Trikafta use improved lung function by an average of 5.23% (p = 8.56e-08). Around a quarter (23%) of all patients reported sleep issues after initiating Trikafta. INTERPRETATION: No significant changes in average PHQ-9 and GAD-7 scores were found after Trikafta initiation. A quarter of patients required a change in psychiatric medications, and significant differences in depression and anxiety scores were found between patients with a change in psychiatric medications and those not prescribed medication. Twenty-three percent of patients reported a prevalence of sleep issues after Trikafta initiation.

The outcome of COVID-19 in children with chronic lung disease: Systematic review and meta-analyses.

BACKGROUND: Few studies have examined the impact of Coronavirus disease 2019 (COVID-19) infection on children with chronic lung disease (CLD). OBJECTIVE: To perform a systematic review and meta-analysis to determine the prevalence, risk factors for contracting COVID-19, and complications of COVID-19, in children with CLD. METHODS: This systematic review was based on articles published between January 1, 2020 and July 25, 2022. Children under 18 years old, with any CLD and infected with COVID-19 were included. RESULTS: Ten articles involving children with asthma and four involving children with cystic fibrosis (CF) were included in the analyses. The prevalence of COVID-19 in children with asthma varied between 0.14% and 19.1%. The use of inhaled corticosteroids (ICS) was associated with reduced risk for COVID-19 (risk ratio [RR]: 0.60, 95% confidence interval [CI]: 0.40-0.90). Uncontrolled asthma, younger age, AND moderate-severe asthma were not significant risk factors for contracting COVID-19. Children with asthma had an increased risk for hospitalization (RR: 1.62, 95% CI: 1.07-2.45) but were not more likely to require assisted ventilation (RR: 0.51, 95% CI: 0.14-1.90). The risk of COVID-19 infection among children with CF was <1%. Posttransplant and cystic fibrosis-related diabetes mellitus (CFRDM) patients were at an increased risk for hospitalization and intensive care treatment. CONCLUSION: Hospitalizations were higher in children with asthma with COVID-19 infection. However, using ICS reduced the risk of COVID-19 infection. As for CF, postlung transplantation and CFRDM were risk factors for severe disease.

A survey assessing the impact of COVID-19 and elexacaftor/tezacaftor/ifavacaftor on both physical and mental health in adults with cystic fibrosis.

In this letter to the editor, we report 82 persons with CF (PwCF) self-reported changes in mental and physical health and potential attribution with either the COVID-19 pandemic and the initiation elexacaftor/tezacaftor/ivacaftor (ETI). Emerging evidence has shown an association with ETI and mental health adverse events. The close proximity of ETI FDA approval and prescribing in PwCF and the COVID-19 pandemic present a challenge in determining the cause of mental health decline. We report 33 (40%) of respondents felt that COVID-19 contributed to a worsening of either their anxiety, depression, or both and 7 (9%) of respondents felt that ETI contributed to a worsening in their anxiety, depression, or both. Eighteen (23%) of respondents felt that ETI had contributed to improvement their mental health. This letter highlights multiple factors that could be impacting mental health beyond ETI. As the COVID-19 pandemic is moving toward an endemic phase, future studies may have more success in deciphering ETI effects on mental health.

Impact of Digital Technologies on Clinical Care for Adults with Cystic Fibrosis.

The coronavirus disease 2019 pandemic accelerated the implementation of digital technologies, which have now become embedded as essential tools for the management of chronic disease, including cystic fibrosis (CF). Despite subsequent easing of restrictions and because of improved clinical stability resulting from the introduction of highly effective modulator therapy, digital technologies including video and telephone consultations and remote monitoring are likely to remain integral to the future delivery of CF health care. In this article, we explore some of the key developments in digital technologies, barriers to their adoption, and how the CF community is likely to embrace lessons learned from the recent pandemic to help modernize and reshape the future of CF care.

Respiratory Viruses and Cystic Fibrosis.

The threat of respiratory virus infection to human health and well-being has been clearly highlighted by the coronavirus disease 2019 (COVID-19) pandemic. For people with cystic fibrosis (CF), the clinical significance of viral infections long predated the emergence of severe acute respiratory syndrome coronavirus 2. This article reviews the epidemiology, diagnosis, and treatment of respiratory virus infection in the context of CF as well as the current understanding of interactions between viruses and other microorganisms in the CF lung. The incidence of respiratory virus infection in CF varies by age with young children typically experiencing more frequent episodes than adolescents and adults. At all ages, respiratory viruses are very common in CF and are associated with pulmonary exacerbations. Respiratory viruses are identified at up to 69% of exacerbations, while viruses are also frequently detected during clinical stability. The full impact of COVID-19 in CF is yet to be established. Early studies found that rates of COVID-19 were lower in CF cohorts than in the general population. The reasons for this are unclear but may be related to the effects of shielding, infection control practices, maintenance CF therapies, or the inflammatory milieu in the CF lung. Observational studies have consistently identified that prior solid organ transplantation is a key risk factor for poor outcomes from COVID-19 in CF. Several key priorities for future research are highlighted. First, the impact of highly effective CFTR modulator therapy on the epidemiology and pathophysiology of viral infections in CF requires investigation. Second, the impact of respiratory viruses on the development and dynamics of the CF lung microbiota is poorly understood and viral infection may have important interactions with bacteria and fungi in the airway. Finally, bacteriophages represent a key focus of future investigation both for their role in transmission of antimicrobial resistance and as a promising treatment modality for multiresistant pathogens.

Advanced Cystic Fibrosis Lung Disease and Lung Transplantation in the Era of Cystic Fibrosis Transmembrane Conductance Regulator Modulators.

Cystic fibrosis transmembrane conductance regulator (CFTR) modulators have changed the clinical landscape of cystic fibrosis (CF) by improving clinically significant outcome measures and quality of life of people with CF (pwCF). There are now long-term data showing improved 5-year survival with the use of ivacaftor, and the field continues to evolve at a rapid pace with the continued development of highly effective CFTR modulators. While the randomized controlled trials of CFTR modulators excluded patients with severe lung disease (forced expiratory volume in 1 second <40% predicted), observational data based on case reports and registry data show similar benefits in those with advanced lung disease. This has altered clinical practice particularly as it pertains to the role of lung transplantation in CF. This article describes the impact of highly effective modulator therapy (HEMT) on the natural history of CF and the influence on the timing of referral and consideration of listing for lung transplantation. CF clinicians play a pivotal role to ensure that the impetus of the CF foundation consensus guidelines to facilitate timely referral for lung transplantation is not lost among the excitement of anticipated sustained benefit from HEMT. While the widespread availability of elexacaftor/tezacaftor/ivacaftor over the past 2 years has been associated with a sharp drop in the number of people referred for consideration for lung transplantation and the number of people wait-listed for lung transplantation, it is difficult to accurately determine the true impact due to the confounding effect of the coronavirus disease 2019 pandemic. It is expected that lung transplantation will remain an important treatment for a smaller number of pwCF. Lung transplantation offers survival benefits in CF, and there remains an imperative to ensure timely consideration of lung transplantation in patients with advanced disease to further reduce the number of pwCF dying without consideration of lung transplant.

Suicide attempts in adolescents with cystic fibrosis on Elexacaftor/Tezacaftor/Ivacaftor therapy.

Elexacaftor/Tezacaftor/Ivacaftor (ETI) is a recently approved cystic fibrosis (CF) transmembrane conductance regulator modulator therapy that has shown promising clinical and laboratory improvements on multiple organ systems in people with CF (pwCF). While original clinical trials found little to no effect on depression and anxiety, many post-marketing reports have suggested that ETI may be associated with adverse mental health effects. Here we report on two pwCF with adverse mental health effects shortly after starting ETI. Although many factors such as the burden of living with a chronic disease or widespread effects of the Covid-19 pandemic may have contributed to these events, similar reports have led to mounting concern that ETI may be the cause of such events. Regular mental health screening before the initiation of ETI and monitoring for signs and symptoms of mental diseases afterward should be a routine part of care, given the gravity of possible outcomes.

CFTR pharmacological modulators: A great advance in cystic fibrosis management.

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.

Potential opportunities and challenges for infection prevention and control for cystic fibrosis in the modern era.

PURPOSE OF REVIEW: We describe recent changes in care for people with cystic fibrosis (PwCF) that could impact infection prevention and control (IP&C) practices. RECENT FINDINGS: Current IP&C guidelines primarily aim to prevent acquisition and transmission of pathogens in PwCF utilizing evidence-based recommendations for healthcare settings. Currently, highly effective modulator therapy (HEMT) is dramatically improving the clinical manifestations of cystic fibrosis and reducing pulmonary exacerbations and hospitalizations. Thus, it is feasible that long-term, sustained improvements in pulmonary manifestations of cystic fibrosis could favorably alter cystic fibrosis microbiology. The COVID-19 pandemic increased the use of virtual care, enabling PwCF to spend less time in healthcare settings and potentially reduce the risk of acquiring cystic fibrosis pathogens. The increasing use of whole genome sequencing (WGS) shows great promise in elucidating sources of cystic fibrosis pathogens, shared strains, and epidemic strains and ultimately could allow the cystic fibrosis community to monitor the safety of changed IP&C practices, if deemed appropriate. Finally, given the nonhealthcare environmental reservoirs for cystic fibrosis pathogens, practical guidance can inform PwCF and their families about potential risks and mitigation strategies. SUMMARY: New developments in the treatment of PwCF, a shift toward virtual care delivery of care, and use of WGS could change future IP&C practices.

Infection control in cystic fibrosis: evolving perspectives and challenges.

PURPOSE OF REVIEW: This article reviews the impact of some of the most recent changes in clinical care management in cystic fibrosis on infection prevention practice and advice for people with cystic fibrosis. RECENT FINDINGS: People with cystic fibrosis (CF) consistently highlight infection control as one of their major concerns. Infection prevention guidance and practice has facilitated successful decreases in rates of many transmissible CF pathogens. The coronavirus disease 2019 pandemic highlighted the clinical significance of respiratory viral infections and has accelerated the implementation of remote monitoring and telemedicine consultations as standard practice in CF. The continued improvement in health of the CF population is being further augmented by the introduction of new therapies, in particular cystic fibrosis transmembrane conductance regulator modulators. Infection prevention will remain pertinent to CF care, but these recent changes in clinical practice will have ongoing implications for infection prevention guidance in CF. SUMMARY: Recent changes in CF clinical care have implications that will lead to further evolution of infection control practice and advice.

Chloride channels in the lung: Challenges and perspectives for viral infections, pulmonary arterial hypertension, and cystic fibrosis.

Fine control over chloride homeostasis in the lung is required to maintain membrane excitability, transepithelial transport as well as intra- and extracellular ion and water homeostasis. Over the last decades, a growing number of chloride channels and transporters have been identified in the cells of the pulmonary vasculature and the respiratory tract. The importance of these proteins is underpinned by the fact that impairment of their physiological function is associated with functional dysregulation, structural remodeling, or hereditary diseases of the lung. This paper reviews the field of chloride channels and transporters in the lung and discusses chloride channels in disease processes such as viral infections including SARS-CoV- 2, pulmonary arterial hypertension, cystic fibrosis and asthma. Although chloride channels have become a hot research topic in recent years, remarkably few of them have been targeted by pharmacological agents. As such, we complement the putative pathophysiological role of chloride channels here with a summary of their therapeutic potential.

Pharmacist-administered audiology screening for pediatric cystic fibrosis patients exposed to high-dose aminoglycosides: A pilot study.

This pilot study successfully implemented a standardized protocol for tablet-based ototoxicity screening in pediatric cystic fibrosis (CF) patients exposed to aminoglycosides. Further studies are needed to assess the impact of implementation in a larger number of patients, as well as to determine barriers that may exist at centers with variation in available resources. This method of ototoxicity screening represents an accessible alternative to traditional audiology testing, and given the continued improvements in expected life span for people with CF, it is imperative that patients have regular access to this type of screening to allow for early identification of medication-related toxicities.

Mechanism of action, resistance, synergism, and clinical implications of azithromycin.

BACKGROUND: Azithromycin (AZM), sold under the name Zithromax, is classified as a macrolide. It has many benefits due to its immunomodulatory, anti-inflammatory, and antibacterial effects. This review aims to study different clinical and biochemisterial aspects and properties of this drug which has a priority based on literature published worldwide. METHODS: Several databases including Web of Science, Google Scholar, PubMed, and Scopus were searched to obtain the relevant studies. RESULTS: AZM mechanism of action including the inhibition of bacterial protein synthesis, inhibition of proinflammatory cytokine production, inhibition of neutrophil infestation, and macrophage polarization alteration, gives it the ability to act against a wide range of microorganisms. Resistant organisms are spreading and being developed because of the irrational use of the drug in the case of dose and duration. AZM shows synergistic effects with other drugs against a variety of organisms. This macrolide is considered a valuable antimicrobial agent because of its use as a treatment for a vast range of diseases such as asthma, bronchiolitis, COPD, cystic fibrosis, enteric infections, STIs, and periodontal infections. CONCLUSIONS: Our study shows an increasing global prevalence of AZM resistance. Thus, synergistic combinations are recommended to treat different pathogens. Moreover, continuous monitoring of AZM resistance by registry centers and the development of more rapid diagnostic assays are urgently needed.

Physiologically-Based Pharmacokinetic-Led Guidance for Patients With Cystic Fibrosis Taking Elexacaftor-Tezacaftor-Ivacaftor With Nirmatrelvir-Ritonavir for the Treatment of COVID-19.

Cystic fibrosis transmembrane conductance regulator (CFTR) modulating therapies, including elexacaftor-tezacaftor-ivacaftor, are primarily eliminated through cytochrome P450 (CYP) 3A-mediated metabolism. This creates a therapeutic challenge to the treatment of coronavirus disease 2019 (COVID-19) with nirmatrelvir-ritonavir in people with cystic fibrosis (CF) due to the potential for significant drug-drug interactions (DDIs). However, the population with CF is more at risk of serious illness following COVID-19 infection and hence it is important to manage the DDI risk and provide treatment options. CYP3A-mediated DDI of elexacaftor-tezacaftor-ivacaftor was evaluated using a physiologically-based pharmacokinetic modeling approach. Modeling was performed incorporating physiological information and drug-dependent parameters of elexacaftor-tezacaftor-ivacaftor to predict the effect of ritonavir (the CYP3A inhibiting component of the combination) on the pharmacokinetics of elexacaftor-tezacaftor-ivacaftor. The elexacaftor-tezacaftor-ivacaftor models were verified using independent clinical pharmacokinetic and DDI data of elexacaftor-tezacaftor-ivacaftor with a range of CYP3A modulators. When ritonavir was administered on Days 1 through 5, the predicted area under the curve (AUC) ratio of ivacaftor (the most sensitive CYP3A substrate) on Day 6 was 9.31, indicating that its metabolism was strongly inhibited. Based on the predicted DDI, the dose of elexacaftor-tezacaftor-ivacaftor should be reduced when coadministered with nirmatrelvir-ritonavir to elexacaftor 200 mg-tezacaftor 100 mg-ivacaftor 150 mg on Days 1 and 5, with delayed resumption of full-dose elexacaftor-tezacaftor-ivacaftor on Day 9, considering the residual inhibitory effect of ritonavir as a mechanism-based inhibitor. The simulation predicts a regimen of elexacaftor-tezacaftor-ivacaftor administered concomitantly with nirmatrelvir-ritonavir in people with CF that will likely decrease the impact of the drug interaction.

Real-World Outcomes in Cystic Fibrosis Telemedicine Clinical Care in a Time of a Global Pandemic.

BACKGROUND: During the COVID-19 pandemic, the University of Virginia adult cystic fibrosis (CF) center transitioned from in-person clinical encounters to a model that included interdisciplinary telemedicine. The pandemic presented an unprecedented opportunity to assess the impact of the interdisciplinary telemedicine model on clinical CF outcomes. RESEARCH QUESTION: What are the clinical outcomes of a care model that includes interdisciplinary telemedicine (IDC-TM) compared with in-person clinical care for patients with CF during the COVID-19 pandemic? STUDY DESIGN AND METHODS: Adults with CF were included. The prepandemic year was defined as March 17, 2019, through March 16, 2020, and the pandemic year (PY) was defined as March 17, 2020, through March 16, 2021. Patients were enrolled starting in the PY. Prepandemic data were gathered retrospectively. Telemedicine visits were defined as clinical encounters via secured video communication. Hybrid visits were in-person evaluations by physician, with in-clinic video communication by other team members. In-person visits were encounters with in-person providers only. All encounters included previsit screening. Outcomes were lung function, BMI, exacerbations, and antibiotic use. FEV1 percent predicted, exacerbations, and antibiotic use were adjusted for the effect of elexacaftor/tezacaftor/ivacaftor treatment. RESULTS: One hundred twenty-four patients participated. One hundred ten patients were analyzed (mean age, 35 years; range, 18-69 years). Ninety-five percent had access to telemedicine (n = 105). Telemedicine visits accounted for 64% of encounters (n = 260), hybrid visits with telemedicine support accounted for 28% of encounters (n = 114), and in-person visits accounted for 7% of encounters (n = 30). No difference in lung function or exacerbation rate during the PY was found. BMI increased from 25 to 26 kg/m2 (t100 = -4.72; P < .001). Antibiotic use decreased from 316 to 124 episodes (z = 8.81; P < .0001). INTERPRETATION: This CF care model, which includes IDC-TM, successfully monitored lung function and BMI, identified exacerbations, and followed guidelines-based care during the pandemic. A significant decrease in antibiotic use suggests that social mitigation strategies were protective. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT04402801; URL: www. CLINICALTRIALS: gov.

The immunomodulatory effects of macrolide antibiotics in respiratory disease.

Macrolide antibiotics are well known for their antibacterial properties, but extensive research in the context of inflammatory lung disease has revealed that they also have powerful immunomodulatory properties. It has been demonstrated that these drugs are therapeutically beneficial in various lung diseases, with evidence they significantly reduce exacerbations in patients with COPD, asthma, bronchiectasis and cystic fibrosis. The efficacy demonstrated in patients infected with macrolide tolerant organisms such as Pseudomonas aeruginosa supports the concept that their efficacy is at least partly related to immunomodulatory rather than antibacterial effects. Inconsistent data and an incomplete understanding of their mechanisms of action hampers the use of macrolide antibiotics as immunomodulatory therapies. Macrolides recently demonstrated no clinically relevant immunomodulatory effects in the context of COVID-19 infection. This review provides an overview of macrolide antibiotics and discusses their immunomodulatory effects and mechanisms of action in the context of inflammatory lung disease.

Protein kinase CK2: a potential therapeutic target for diverse human diseases.

CK2 is a constitutively active Ser/Thr protein kinase, which phosphorylates hundreds of substrates, controls several signaling pathways, and is implicated in a plethora of human diseases. Its best documented role is in cancer, where it regulates practically all malignant hallmarks. Other well-known functions of CK2 are in human infections; in particular, several viruses exploit host cell CK2 for their life cycle. Very recently, also SARS-CoV-2, the virus responsible for the COVID-19 pandemic, has been found to enhance CK2 activity and to induce the phosphorylation of several CK2 substrates (either viral and host proteins). CK2 is also considered an emerging target for neurological diseases, inflammation and autoimmune disorders, diverse ophthalmic pathologies, diabetes, and obesity. In addition, CK2 activity has been associated with cardiovascular diseases, as cardiac ischemia-reperfusion injury, atherosclerosis, and cardiac hypertrophy. The hypothesis of considering CK2 inhibition for cystic fibrosis therapies has been also entertained for many years. Moreover, psychiatric disorders and syndromes due to CK2 mutations have been recently identified. On these bases, CK2 is emerging as an increasingly attractive target in various fields of human medicine, with the advantage that several very specific and effective inhibitors are already available. Here, we review the literature on CK2 implication in different human pathologies and evaluate its potential as a pharmacological target in the light of the most recent findings.

Drug therapies for reducing gastric acidity in people with cystic fibrosis.

BACKGROUND: Malabsorption of fat and protein contributes to poor nutritional status in people with cystic fibrosis. Impaired pancreatic function may also result in increased gastric acidity, leading in turn to heartburn, peptic ulcers and the impairment of oral pancreatic enzyme replacement therapy. The administration of gastric acid-reducing agents has been used as an adjunct to pancreatic enzyme therapy to improve absorption of fat and gastro-intestinal symptoms in people with cystic fibrosis. It is important to establish the evidence regarding potential benefits of drugs that reduce gastric acidity in people with cystic fibrosis. This is an update of a previously published review. OBJECTIVES: To assess the effect of drug therapies for reducing gastric acidity for: nutritional status; symptoms associated with increased gastric acidity; fat absorption; lung function; quality of life and survival; and to determine if any adverse effects are associated with their use. SEARCH METHODS: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register which comprises references identified from comprehensive electronic and non-electronic database searches, handsearches of relevant journals,  abstract books and conference proceedings. Both authors double checked the reference lists of the searches Most recent search of the Group's Trials Register: 26 April 2021. On the 26 April 2021 further searches were conducted on the clinicaltrials.gov register to identify any ongoing trials that may be of relevance. The WHO ICTRP database was last searched in 2020 and is not currently available for searching due to the Covid-19 pandemic. SELECTION CRITERIA: All randomised and quasi-randomised trials involving agents that reduce gastric acidity compared to placebo or a comparator treatment. DATA COLLECTION AND ANALYSIS: Both authors independently selected trials, assessed trial quality and extracted data. MAIN RESULTS: The searches identified 40 trials; 17 of these, with 273 participants, were suitable for inclusion, but the number of trials assessing each of the different agents was small. Seven trials were limited to children and four trials enrolled only adults. Meta-analysis was not performed, 14 trials were of a cross-over design and we did not have the appropriate information to conduct comprehensive meta-analyses. All the trials were run in single centres and duration ranged from five days to six months. The included trials were generally not reported adequately enough to allow judgements on risk of bias. However, one trial found that drug therapies that reduce gastric acidity improved gastro-intestinal symptoms such as abdominal pain; seven trials reported significant improvement in measures of fat malabsorption; and two trials reported no significant improvement in nutritional status. Only one trial reported measures of respiratory function and one trial reported an adverse effect with prostaglandin E2 analogue misoprostol. No trials have been identified assessing the effectiveness of these agents in improving quality of life, the complications of increased gastric acidity, or survival. AUTHORS' CONCLUSIONS: Trials have shown limited evidence that agents that reduce gastric acidity are associated with improvement in gastro-intestinal symptoms and fat absorption. Currently, there is insufficient evidence to indicate whether there is an improvement in nutritional status, lung function, quality of life, or survival. Furthermore, due to the unclear risks of bias in the included trials, we are unable to make firm conclusions based on the evidence reported therein. We therefore recommend that large, multicentre, randomised controlled clinical trials are undertaken to evaluate these interventions.