Prime editing functionally corrects cystic fibrosis-causing CFTR mutations in human organoids and airway epithelial cells.

Prime editing is a recent, CRISPR-derived genome editing technology capable of introducing precise nucleotide substitutions, insertions, and deletions. Here, we present prime editing approaches to correct L227R- and N1303K-CFTR, two mutations that cause cystic fibrosis and are not eligible for current market-approved modulator therapies. We show that, upon DNA correction of the CFTR gene, the complex glycosylation, localization, and, most importantly, function of the CFTR protein are restored in HEK293T and 16HBE cell lines. These findings were subsequently validated in patient-derived rectal organoids and human nasal epithelial cells. Through analysis of predicted and experimentally identified candidate off-target sites in primary stem cells, we confirm previous reports on the high prime editor (PE) specificity and its potential for a curative CF gene editing therapy. To facilitate future screening of genetic strategies in a translational CF model, a machine learning algorithm was developed for dynamic quantification of CFTR function in organoids (DETECTOR: "detection of targeted editing of CFTR in organoids").

Distribution of pathogenic variants in the CFTR gene in a representative cohort of people with cystic fibrosis in the Kingdom of Bahrain.

BACKGROUND: Cystic fibrosis (CF) is a rare multi-systemic recessive disorder. The spectrum and the frequencies of CFTR mutations causing CF vary amongst different populations in Europe and the Middle East. In this study, we characterised the distribution of CF-causing mutations (i.e. pathogenic variants in the  CFTR gene) in a representative CF cohort from the Kingdom of Bahrain based on a three-decade-long analysis at a single tertiary centre. We aim to improve CF genetic diagnostics, introduce of CF neonatal screening and provide CFTR modulator therapy (CFTRm). METHODS: CFTR genotyping  and associated clinical information were drawn from a longitudinal cohort. We sequenced 56 people with CF (pwCF) that had one or both CFTR mutations unidentified and carried out comprehensive bioinformatic- and family-based segregation analyses of detected variants, including genotype-phenotype correlations and disease incidence estimates. The study methodology could serve as a basis for other non-European CF populations with a high degree of consanguinity. RESULTS: Altogether 18 CF-causing mutations  were identified, 15 of which were not previously detected in Bahrain, accounting for close to 100% of all population-specific alleles. The most common alleles comprise c.1911delG [2043delG; 22.8%], c.2988+1G > A [3120+1G>A; 16.3%], c.2989-1G>A [3121-1G>A; 14.1%], c.3909C>G [N1303K; 13.0%], and c.1521_1523delCTT [p.PheF508del; 7.6%]. Although the proportion of 1st cousin marriages has decreased to 50%, the frequency of homozygosity in our pwCF is 67.4%, thereby indicating that CF still occurs in large, often related, families. pwCF in Bahrain present with faltering growth, pancreatic insufficiency and classical sino-pulmonary manifestations. Interestingly, two pwCF also suffer from sickle cell disease. The estimated incidence of CF in Bahrain based on data from the last three decades is 1 in 9,880 live births. CONCLUSION: The most commonCF-causing  mutations in Bahraini pwCF were identified, enabling more precise diagnosis, introduction of two-tier neonatal screening and fostering administration of CFTRm.

A new era of targeting cystic fibrosis with non-viral delivery of genomic medicines.

Cystic fibrosis (CF) is a complex genetic respiratory disorder that necessitates innovative gene delivery strategies to address the mutations in the gene. This review delves into the promises and challenges of non-viral gene delivery for CF therapy and explores strategies to overcome these hurdles. Several emerging technologies and nucleic acid cargos for CF gene therapy are discussed. Novel formulation approaches including lipid and polymeric nanoparticles promise enhanced delivery through the CF mucus barrier, augmenting the potential of non-viral strategies. Additionally, safety considerations and regulatory perspectives play a crucial role in navigating the path toward clinical translation of gene therapy.

Identification of an ultra-rare Alu insertion in the CFTR gene: Pitfalls and challenges in genetic test interpretation.

Cystic fibrosis (CF) is a life-limiting genetic disorder characterized by defective chloride ion transport due to mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Early detection through newborn screening programs significantly improves outcomes for individuals with CF by enabling timely intervention. Here, we report the identification of an Alu element insertion within the exon 15 of CFTR gene, initially overlooked in standard next-generation sequencing analyses. However, using traditional molecular techniques, based on polymerase chain reaction and Sanger sequencing, allowed the identification of the Alu element and the reporting of a correct diagnosis. Our analysis, based on bioinformatics tools and molecular techniques, revealed that the Alu element insertion severely affects the gene expression, splicing patterns, and structure of CFTR protein. In conclusion, this study emphasizes the importance of how the integration of human expertise and modern technologies represents a pivotal step forward in genomic medicine, ensuring the delivery of precision healthcare to individuals affected by genetic diseases.

Predicting lung function decline in cystic fibrosis: the impact of initiating ivacaftor therapy.

BACKGROUND: Modulator therapies that seek to correct the underlying defect in cystic fibrosis (CF) have revolutionized the clinical landscape. Given the heterogeneous nature of lung disease progression in the post-modulator era, there is a need to develop prediction models that are robust to modulator uptake. METHODS: We conducted a retrospective longitudinal cohort study of the CF Foundation Patient Registry (N = 867 patients carrying the G551D mutation who were treated with ivacaftor from 2003 to 2018). The primary outcome was lung function (percent predicted forced expiratory volume in 1 s or FEV1pp). To characterize the association between ivacaftor initiation and lung function, we developed a dynamic prediction model through covariate selection of demographic and clinical characteristics. The ability of the selected model to predict a decline in lung function, clinically known as an FEV1-indicated exacerbation signal (FIES), was evaluated both at the population level and individual level. RESULTS: Based on the final model, the estimated improvement in FEV1pp after ivacaftor initiation was 4.89% predicted (95% confidence interval [CI]: 3.90 to 5.89). The rate of decline was reduced with ivacaftor initiation by 0.14% predicted/year (95% CI: 0.01 to 0.27). More frequent outpatient visits prior to study entry and being male corresponded to a higher overall FEV1pp. Pancreatic insufficiency, older age at study entry, a history of more frequent pulmonary exacerbations, lung infections, CF-related diabetes, and use of Medicaid insurance corresponded to lower FEV1pp. The model had excellent predictive accuracy for FIES events with an area under the receiver operating characteristic curve of 0.83 (95% CI: 0.83 to 0.84) for the independent testing cohort and 0.90 (95% CI: 0.89 to 0.90) for 6-month forecasting with the masked cohort. The root-mean-square errors of the FEV1pp predictions for these cohorts were 7.31% and 6.78% predicted, respectively, with standard deviations of 0.29 and 0.20. The predictive accuracy was robust across different covariate specifications. CONCLUSIONS: The methods and applications of dynamic prediction models developed using data prior to modulator uptake have the potential to inform post-modulator projections of lung function and enhance clinical surveillance in the new era of CF care.

A promoter-dependent upstream activator augments CFTR expression in diverse epithelial cell types.

The cystic fibrosis transmembrane conductance regulator (CFTR) gene encodes an anion-selective channel found in epithelial cell membranes. Mutations in CFTR cause cystic fibrosis (CF), an inherited disorder that impairs epithelial function in multiple organs. Most men with CF are infertile due to loss of intact genital ducts. Here we investigated a novel epididymis-selective cis-regulatory element (CRE), located within a peak of open chromatin at -9.5 kb 5' to the CFTR gene promoter. Activation of the -9.5 kb CRE alone by CRISPRa had no impact on CFTR gene expression. However, CRISPRa co-activation of the -9.5 kb CRE and the CFTR gene promoter in epididymis cells significantly augmented CFTR mRNA and protein expression when compared to promoter activation alone. This increase was accompanied by enhanced chromatin accessibility at both sites. Furthermore, the combined CRISPRa strategy activated CFTR expression in other epithelial cells that lack open chromatin at the -9.5 kb site and in which the locus is normally inactive. However, the -9.5 kb CRE does not function as a classical enhancer of the CFTR promoter in transient reporter gene assays. These data provide a novel mechanism for activating/augmenting CFTR expression, which may have therapeutic utility for mutations that perturb CFTR transcription.

In utero and postnatal ivacaftor/lumacaftor therapy rescues multiorgan disease in CFTR-F508del ferrets.

Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR) gene, with F508del being the most prevalent mutation. The combination of CFTR modulators (potentiator and correctors) has provided benefit to CF patients carrying the F508del mutation; however, the safety and effectiveness of in utero combination modulator therapy remains unclear. We created a F508del ferret model to test whether ivacaftor/lumacaftor (VX-770/VX-809) therapy can rescue in utero and postnatal pathologies associated with CF. Using primary intestinal organoids and air-liquid interface cultures of airway epithelia, we demonstrate that the F508del mutation in ferret CFTR results in a severe folding and trafficking defect, which can be partially restored by treatment with CFTR modulators. In utero treatment of pregnant jills with ivacaftor/lumacaftor prevented meconium ileus at birth in F508del kits and sustained postnatal treatment of CF offspring improved survival and partially protected from pancreatic insufficiency. Withdrawal of ivacaftor/lumacaftor treatment from juvenile CF ferrets reestablished pancreatic and lung diseases, with altered pulmonary mechanics. These findings suggest that in utero intervention with a combination of CFTR modulators may provide therapeutic benefits to individuals with F508del. This CFTR-F508del ferret model may be useful for testing therapies using clinically translatable endpoints.

Mutational spectrum of CFTR in cystic fibrosis patients with gastrointestinal and hepatobiliary manifestations.

BACKGROUND: Cystic fibrosis (CF) is a rare and debilitating autosomal recessive disorder. It hampers the normal function of various organs and causes severe damage to the lungs, and digestive system leading to recurring pneumonia. Cf also affects reproductive health eventually may cause infertility. The disease manifests due to genetic aberrations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. This study aimed to screen for CFTR gene variants in Pakistani CF patients representing variable phenotypes. METHODS: Clinical exome and Sanger sequencing were performed after clinical characterization of 25 suspected cases of CF (CF1-CF25). ACMG guidelines were followed to interpret the clinical significance of the identified variants. RESULTS: Clinical investigations revealed common phenotypes such as pancreatic insufficiency, chest infections, chronic liver and lung diseases. Some patients also displayed symptoms like gastroesophageal reflux disease (GERD), neonatal cholestasis, acrodermatitis, diabetes mellitus, and abnormal malabsorptive stools. Genetic analysis of the 25 CF patients identified deleterious variants in the CFTR gene. Notably, 12% of patients showed compound heterozygous variants, while 88% had homozygous variants. The most prevalent variant was p. (Met1Thr or Met1?) at 24%, previously not reported in the Pakistani population. The second most common variant was p. (Phe508del) at 16%. Other variants, including p. (Leu218*), p. (Tyr569Asp), p. (Glu585Ter), and p. (Arg1162*) were also identified in the present study. Genetic analysis of one of the present patients showed a pathogenic variant in G6PD in addition to CFTR. CONCLUSION: The study reports novel and reported variants in the CFTR gene in CF patients in Pakistani population having distinct phenotypes. It also emphasizes screening suspected Pakistani CF patients for the p. (Met1Thr) variant because of its increased observance and prevalence in the study. Moreover, the findings also signify searching for additional pathogenic variants in the genome of CF patients, which may modify the phenotypes. The findings contribute valuable information for the diagnosis, genetic counseling, and potential therapeutic strategies for CF patients in Pakistan.

Cystic Fibrosis Foundation Evidence-Based Guideline for the Management of CRMS/CFSPID.

A multidisciplinary committee developed evidence-based guidelines for the management of cystic fibrosis transmembrane conductance regulator-related metabolic syndrome/cystic fibrosis screen-positive, inconclusive diagnosis (CRMS/CFSPID). A total of 24 patient, intervention, comparison, and outcome questions were generated based on surveys sent to people with CRMS/CFSPID and clinicians caring for these individuals, previous recommendations, and expert committee input. Four a priori working groups (genetic testing, monitoring, treatment, and psychosocial/communication issues) were used to provide structure to the committee. A systematic review of the evidence was conducted, and found numerous case series and cohort studies, but no randomized clinical trials. A total of 30 recommendations were graded using the US Preventive Services Task Force methodology. Recommendations that received ≥80% consensus among the entire committee were approved. The resulting recommendations were of moderate to low certainty for the majority of the statements because of the low quality of the evidence. Highlights of the recommendations include thorough evaluation with genetic sequencing, deletion/duplication analysis if <2 disease-causing variants were noted in newborn screening; repeat sweat testing until at least age 8 but limiting further laboratory testing, including microbiology, radiology, and pulmonary function testing; minimal use of medications, which when suggested, should lead to shared decision-making with families; and providing communication with emphasis on social determinants of health and shared decision-making to minimize barriers which may affect processing and understanding of this complex designation. Future research will be needed regarding medication use, antibiotic therapy, and the use of chest imaging for monitoring the development of lung disease.

Pulmonary Vascular Dysfunctions in Cystic Fibrosis.

Cystic fibrosis (CF) is an inherited disorder caused by a deleterious mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Given that the CFTR protein is a chloride channel expressed on a variety of cells throughout the human body, mutations in this gene impact several organs, particularly the lungs. For this very reason, research regarding CF disease and CFTR function has historically focused on the lung airway epithelium. Nevertheless, it was discovered more than two decades ago that CFTR is also expressed and functional on endothelial cells. Despite the great strides that have been made in understanding the role of CFTR in the airway epithelium, the role of CFTR in the endothelium remains unclear. Considering that the airway epithelium and endothelium work in tandem to allow gas exchange, it becomes very crucial to understand how a defective CFTR protein can impact the pulmonary vasculature and overall lung function. Fortunately, more recent research has been dedicated to elucidating the role of CFTR in the endothelium. As a result, several vascular dysfunctions associated with CF disease have come to light. Here, we summarize the current knowledge on pulmonary vascular dysfunctions in CF and discuss applicable therapies.

Diversity of CFTR variants across ancestries characterized using 454,727 UK biobank whole exome sequences.

BACKGROUND: Limited understanding of the diversity of variants in the cystic fibrosis transmembrane conductance regulator (CFTR) gene across ancestries hampers efforts to advance molecular diagnosis of cystic fibrosis (CF). The consequences pose a risk of delayed diagnoses and subsequently worsened health outcomes for patients. Therefore, characterizing the spectrum of CFTR variants across ancestries is critical for revolutionizing molecular diagnoses of CF. METHODS: We analyzed 454,727 UK Biobank (UKBB) whole-exome sequences to characterize the diversity of CFTR variants across ancestries. Using the PanUKBB classification, the participants were assigned into six major groups: African (AFR), American/American Admixed (AMR), Central South Asia (CSA), East Asian (EAS), European (EUR), and Middle East (MID). We segregated ancestry-specific CFTR variants, including those that are CF-causing or clinically relevant. The ages of certain CF-causing variants were determined and analyzed for selective pressure effects, and curated phenotype analysis was performed for participants with clinically relevant CFTR genotypes. RESULTS: We detected over 4000 CFTR variants, including novel ancestry-specific variants, across six ancestries. Europeans had the most unique CFTR variants [n = 2212], while the American group had the least unique variants [n = 23]. F508del was the most prevalent CF-causing variant found in all ancestries, except in EAS, where V520F was the most prevalent. Common EAS variants such as 3600G > A, V456A, and V520, which appeared approximately 270, 215, and 338 generations ago, respectively, did not show evidence of selective pressure. Sixteen participants had two CF-causing variants, with two being diagnosed with CF. We found 154 participants harboring a CF-causing and varying clinical consequences (VCC) variant. Phenotype analysis performed for participants with multiple clinically relevant variants returned significant associations with CF and its pulmonary phenotypes [Bonferroni-adjusted p < 0.05]. CONCLUSIONS: We leveraged the UKBB database to comprehensively characterize the broad spectrum of CFTR variants across ancestries. The detection of over 4000 CFTR variants, including several ancestry-specific and uncharacterized CFTR variants, warrants the need for further characterization of their functional and clinical relevance. Overall, the presentation of classical CF phenotypes seen in non-CF diagnosed participants with more than one CF-causing variant indicates that they may benefit from current CFTR modulator therapies.

Prevalence of common autosomal recessive mutation carriers in women in the Southern Vietnam following the application of expanded carrier screening.

The common autosomal recessive (AR) mutation carrier is still unknown in Vietnam. This study aims to identify the most common AR gene mutation carriers in women of reproductive age to build a Vietnamese-specific carrier screening panel for AR and X-linked disorders in the preconception and prenatal healthcare program. A cross-sectional study was conducted at University Medical Center-Branch 2 in Ho Chi Minh City from December 1st, 2020, to June 30th, 2023. 338 women have consented to take a 5 mL blood test to identify 540 recessive genes. The carrier screening panel was designed based on the American College of Medical Genetics and Genomics (ACMG)-recommended genes and suggestions from 104 clinical experts in Vietnam. Obstetricians and genetic experts counseled all positive testing results to discuss the possibility of recessive diseases in their offspring. The most common recessive disorders were defined at a prevalence of 1 in 60 or greater, and those were added to a Vietnamese-specific carrier screening panel. 338 non-pregnant and pregnant women underwent the expanded carrier screening (ECS). The carrier frequency was 63.6%, in which 215 women carried at least one AR gene mutation. GJB2 hearing impairment was identified as the most common chronic condition (1 in 5). The second most common AR disorder was beta-thalassemia (1 in 16), followed by cystic fibrosis (1 in 23), G6PD deficiency (1 in 28), Wilson's disease (1 in 31), Usher's syndrome (1 in 31), and glycogen storage disease (1 in 56). Seven common recessive genes were added in ethnic-based carrier screening. Women in the South of Vietnam have been carried for many recessive conditions at high frequency, such as hearing impairment, genetic anemia, and cystic fibrosis. It is necessary to implement a preconception and prenatal screening program by using seven widely popular AR genes in a Vietnamese-specific carrier screening panel to reduce the burden related to AR and X-linked disorders.

Functional rescue of CFTR in rectal organoids from patients carrying R334W variant by CFTR modulators and PDE4 inhibitor Roflumilast.

BACKGROUND: Many disease-causing variants in the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) gene remain uncharacterized and untreated. Restoring the function of the impaired CFTR protein is the goal of personalized medicine, particularly in patients carrying rare CFTR variants. In this study, functional defects related to the rare R334W variant were evaluated after treatment with CFTR modulators or Roflumilast, a phosphodiesterase-4 inhibitor (PDE4i). METHODS: Rectal organoids from subjects with R334W/2184insA and R334W/2183AA > G genotypes were used to perform the Forskolin-induced swelling (FIS) assay. Organoids were left drug-untreated or treated with modulators VX-770 (I), VX-445 (E), and VX-661 (T) mixed, and their combination (ETI). Roflumilast (R) was used alone or as a combination of I + R. RESULTS: Our data show a significant increase in FIS rate following treatment with I alone. The combined use of modulators, such as ETI, did not increase further swelling than I alone, nor in protein maturation. Treatment with R shows an increase in FIS response similar to those of I, and the combination R + I significantly increases the rescue of CFTR activity. CONCLUSIONS: Equivalent I and ETI treatment efficacy was observed for both genotypes. Furthermore, significant organoid swelling was observed with combined I + R used that supports the recently published data describing a potentiating effect of only I in patients carrying the variant R334W and, at the same time, corroborating the role of strategies that include PDE4 inhibitors further to potentiate the effect of I for this variant.

Influence of the BsmI polymorphism of the vitamin D receptor gene on the levels of vitamin D, inflammatory and oxidative stress profile in patients with cystic fibrosis supplemented with Colecalciferol megadose.

OBJECTIVE: Evaluate the influence of the BsmI polymorphism of the vitamin D receptor gene on vitamin D levels, and inflammatory and oxidative stress markers in patients with Cystic Fibrosis supplemented with cholecalciferol megadose. METHODS: We performed a single-arm, non-randomized pre- and post-study of 17 patients aged 5 to 20 years with cystic fibrosis diagnosed with vitamin D insufficiency/deficiency 25-hydroxy vitamin< 30 ng/mL. Individuals were genotyped for the BsmI polymorphism of the vitamin D receptor gene and all received cholecalciferol supplementation of 4,000 IU daily for children aged 5 to 10 years and 10,000 IU for children over 10 years of age for 8 weeks. Interviews were conducted with personal data, sun exposure, anthropometric and blood samples of 25-hydroxy vitamin parathormone, serum calcium, ultrasensitive C-reactive protein, alpha 1 acid glycoprotein, total antioxidant capacity, malondialdehyde and kidney and liver function. Inter- and intra-group assessment was assessed by paired t-test Anova test or its non-parametric counterparts. RESULTS: The individuals were mostly male and reported no adverse effects from the use of supplementation, 64 % had 25-hydroxy vitamin levels >30 ng/mL. Patients with BB and Bb genotypes showed increased serum levels of 25-hydroxy vitamin. The group with BB genotype showed a reduction in alpha 1 acid glycoprotein. And individuals with the bb genotype had high levels of malondialdehyde compared to the pre-intervention time. CONCLUSION: It is concluded that variations of the BsmI polymorphism of the vitamin D receptor gene have different responses in vitamin D levels and markers of inflammation and oxidative stress.

Discovery of GLPG2737, a Potent Type 2 Corrector of CFTR for the Treatment of Cystic Fibrosis in Combination with a Potentiator and a Type 1 Co-corrector.

Cystic fibrosis (CF) is caused by mutations in the CF transmembrane conductance regulator (CFTR) protein. This epithelial anion channel regulates the active transport of chloride and bicarbonate ions across membranes. Mutations result in reduced surface expression of CFTR channels with impaired functionality. Correctors are small molecules that support the trafficking of CFTR to increase its membrane expression. Such correctors can have different mechanisms of action. Combinations may result in a further improved therapeutic benefit. We describe the identification and optimization of a new pyrazolol3,4-bl pyridine-6-carboxylic acid series with high potency and efficacy in rescuing CFTR from the cell surface. Investigations showed that carboxylic acid group replacement with acylsulfonamides and acylsulfonylureas improved ADMET and PK properties, leading to the discovery of the structurally novel co-corrector GLPG2737. The addition of GLPG2737 to the combination of the potentiator GLPG1837 and C1 corrector 4 led to an 8-fold increase in the F508del CFTR activity.

Abnormal functional lymphoid tolerance and enhanced myeloid exocytosis are characteristics of resting and stimulated PBMCs in cystic fibrosis patients.

Introduction: Cystic Fibrosis (CF) is the commonest genetically inherited disease (1 in 4,500 newborns) and 70% of people with CF (pwCF) harbour the F508Del mutation, resulting in misfolding and incorrect addressing of the channel CFTR to the epithelial membrane and subsequent dysregulation of fluid homeostasis. Although studies have underscored the importance and over-activation of myeloid cells, and in particular neutrophils in the lungs of people with CF (pwCF), relatively less emphasis has been put on the potential immunological bias in CF blood cells, at homeostasis or following stimulation/infection. Methods: Here, we revisited, in an exhaustive fashion, in pwCF with mild disease (median age of 15, median % FEV1 predicted = 87), whether their PBMCs, unprimed or primed with a 'non specific' stimulus (PMA+ionomycin mix) and a 'specific' one (live P.a =PAO1 strain), were differentially activated, compared to healthy controls (HC) PBMCs. Results: 1) we analysed the lymphocytic and myeloid populations present in CF and Control PBMCs (T cells, NKT, Tgd, ILCs) and their production of the signature cytokines IFN-g, IL-13, IL-17, IL-22. 2) By q-PCR, ELISA and Luminex analysis we showed that CF PBMCs have increased background cytokines and mediators production and a partial functional tolerance phenotype, when restimulated. 3) we showed that CF PBMCs low-density neutrophils release higher levels of granule components (S100A8/A9, lactoferrin, MMP-3, MMP-7, MMP-8, MMP-9, NE), demonstrating enhanced exocytosis of potentially harmful mediators. Discussion: In conclusion, we demonstrated that functional lymphoid tolerance and enhanced myeloid protease activity are key features of cystic fibrosis PBMCs.

Use of CFTR Modulators for Cystic Fibrosis in a Patient with Liver Transplant and ESRD on Hemodialysis.

Cystic fibrosis is an autosomal recessive disorder caused by mutations of the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein. The most recent therapeutic approach to cystic fibrosis aims to correct structural and functional abnormalities of CFTR protein. CFTR modulators including ivacaftor-tezacaftor-elexacaftor are used in patients with F508del mutation, with clinical improvement. To date, there are no experiences of CFTR modulator therapy in cystic fibrosis patients with organ transplantation and severe renal impairment. We report the case of a patient diagnosed with cystic fibrosis with F508del mutation, who underwent liver transplantation at the age of 19 and started hemodialysis at the age of 24 due to end-stage renal disease secondary to membranous glomerulonephritis. She was treated with Kaftrio (ivacaftor-tezacaftor-elexacaftor) with clinical benefits on appetite, improvement of body mass index, and reduction of pulmonary exacerbations. A reduction of dosage to 75% of the standard dose was required due to alterations of the liver function. Conclusions. Use of CFTR modulators in patient with cystic fibrosis, liver transplant and end-stage renal disease could be considered safe but a clinical and laboratoristic monitoring of hepatic function is needed.

CFTR function is impaired in a subset of patients with pancreatitis carrying rare CFTR variants.

BACKGROUND: Many affected by pancreatitis harbor rare variants of the cystic fibrosis (CF) gene, CFTR, which encodes an epithelial chloride/bicarbonate channel. We investigated CFTR function and the effect of CFTR modulator drugs in pancreatitis patients carrying CFTR variants. METHODS: Next-generation sequencing was performed to identify CFTR variants. Sweat tests and nasal potential difference (NPD) assays were performed to assess CFTR function in vivo. Intestinal current measurement (ICM) was performed on rectal biopsies. Patient-derived intestinal epithelial monolayers were used to evaluate chloride and bicarbonate transport and the effects of a CFTR modulator combination: elexacaftor, tezacaftor and ivacaftor (ETI). RESULTS: Of 32 pancreatitis patients carrying CFTR variants, three had CF-causing mutations on both alleles and yielded CF-typical sweat test, NPD and ICM results. Fourteen subjects showed a more modest elevation in sweat chloride levels, including three that were provisionally diagnosed with CF. ICM indicated impaired CFTR function in nine out of 17 non-CF subjects tested. This group of nine included five carrying a wild type CFTR allele. In epithelial monolayers, a reduction in CFTR-dependent chloride transport was found in six out of 14 subjects tested, whereas bicarbonate secretion was reduced in only one individual. In epithelial monolayers of four of these six subjects, ETI improved CFTR function. CONCLUSIONS: CFTR function is impaired in a subset of pancreatitis patients carrying CFTR variants. Mutations outside the CFTR locus may contribute to the anion transport defect. Bioassays on patient-derived intestinal tissue and organoids can be used to detect such defects and to assess the effect of CFTR modulators.

[Therapeutics in cystic fibrosis: Clinical revolution and new challenges]. / Traitements de la mucoviscidose - Révolution clinique et nouveaux défis.

Over time, cystic fibrosis has become a model of synergy between research in pathophysiology and cell biology, and clinical advances. Therapies targeting the CFTR protein, in particular CFTR modulators, have transformed the prognosis of patients, bringing the hope of a normal life with the possibility of starting a family and growing old, challenging established statistics. However, patients are not yet cured, and side effects remain insufficiently documented. Epidemiological changes create new challenges for the management of cystic fibrosis. Approximately 10 % of patients still lack a therapeutic option. The community of researchers, pharmaceutical industries, patient associations, and health authorities remains committed to monitor the long-term effects of these still poorly characterised treatments, and to explore new pharmacological approaches, such as gene therapies.

Title: Traitements de la mucoviscidose - Révolution clinique et nouveaux défis. Abstract: Avec le temps, la mucoviscidose est devenue un exemple de synergie entre la recherche en biologie cellulaire et les progrès cliniques. Les thérapies protéiques ont enfin apporté l'espoir d'une vie normale aux patients, bouleversant ainsi les statistiques épidémiologiques établies. Néanmoins, les patients ne guérissent pas, et l'évolution épidémiologique de la maladie ouvre de nouveaux défis pour la prise en charge des malades. Par ailleurs, environ 10 % des patients demeurent sans solution thérapeutique. De nouvelles stratégies sont ainsi envisagées et la communauté des chercheurs, industriels, patients et autorités de santé reste mobilisée pour suivre les effets à long terme de ces nouveaux traitements et explorer de nouvelles approches pharmacologiques.