Long term clinical effectiveness of ivacaftor in people with the G551D CFTR mutation

Amelioration of airway and GI disease in G551D-CF ferrets by AAV1 and AAV6

Gene therapy for CF has concentrated on targeting the lung. Here we took a different approach by injecting into the cephalic vein and spraying into the trachea of G551D, CF ferrets either AAV1 or 6 containing Δ27-264-CFTR, a truncated version of CFTR. Treatment with the potentiator VX-770 was halted for 7 days before instillation to induce a disease phenotype. Indeed, all ferrets were pancreas-insufficient when they entered the study. Four ferrets (three receiving AAV1 and one AAV6) were necropsied 48 days after vector delivery, and four (three receiving AAV6, one AAV1) were euthanized or died prior to the planned necropsy. AAV1 or AAV6 vector genomes, mRNA expression, and CFTR protein were detected in all tracheal and lung samples and in the liver, pancreas, and ileum of the treated ferrets. Surface and basal airway cells, pancreatic and bile ducts, and ileal crypts and villi were successfully transduced. Obstruction of the airways accompanied by pulmonary hemorrhaging, plugged pancreatic and bile ducts as well as mucous plugs in the ileum were noticed in untreated but absent from transduced ferrets necropsied at 48 days. Transduction of G551D ferrets suggests that a combination of systemic and airway application may be the preferred route of delivery for CF.

Systematic optimization of prime editing for the efficient functional correction of CFTR F508del in human airway epithelial cells

Prime editing (PE) enables precise and versatile genome editing without requiring double-stranded DNA breaks. Here we describe the systematic optimization of PE systems to efficiently correct human cystic fibrosis (CF) transmembrane conductance regulator (CFTR) F508del, a three-nucleotide deletion that is the predominant cause of CF. By combining six efficiency optimizations for PE-engineered PE guide RNAs, the PEmax architecture, the transient expression of a dominant-negative mismatch repair protein, strategic silent edits, PE6 variants and proximal 'dead' single-guide RNAs-we increased correction efficiencies for CFTR F508del from less than 0.5% in HEK293T cells to 58% in immortalized bronchial epithelial cells (a 140-fold improvement) and to 25% in patient-derived airway epithelial cells. The optimizations also resulted in minimal off-target editing, in edit-to-indel ratios 3.5-fold greater than those achieved by nuclease-mediated homology-directed repair, and in the functional restoration of CFTR ion channels to over 50% of wild-type levels (similar to those achieved via combination treatment with elexacaftor, tezacaftor and ivacaftor) in primary airway cells. Our findings support the feasibility of a durable one-time treatment for CF.

Sex Differences Persist After Treatment With Ivacaftor in People With Cystic Fibrosis

BACKGROUND

Historically, studies show that female patients with cystic fibrosis (CF) have worse pulmonary outcomes than male patients, including decreased life expectancy. It is unknown whether this disparity persists in the new era of highly effective modulator therapies. Ivacaftor has been available in the United States for > 10 years, allowing for the opportunity to understand the impact this therapy may have on sex disparities in CF. We hypothesized that female patients will continue to show worse outcomes because we suspect that the disparity is not driven solely by ion channel dysfunction.

RESEARCH QUESTION

Does a difference in outcomes between male and female patients persist after the initiation of ivacaftor in people with CF?

STUDY DESIGN AND METHODS

We conducted a retrospective cohort study using the CF Foundation Patient Registry comparing changes in pulmonary exacerbation rate, lung function (FEV1 % predicted), and presence of Pseudomonas aeruginosa among male patients vs female patients before and after initiation of treatment with the highly effective modulator ivacaftor.

RESULTS

The cohort comprised 1,900 people with CF who were treated with ivacaftor between 2010 and 2017; 928 patients (48.84%) were male and 972 patients (51.16%) were female with a mean age of 33.09 years. Male patients showed a significant decrease in pulmonary exacerbations after ivacaftor treatment (from 0.38 to 0.34; adjusted rate ratio, 0.89; P = .028), whereas female patients did not (from 0.48 to 0.45; adjusted rate ratio, 0.95; P = .174). FEV1 % predicted similarly decreased in both male and female patients before vs after ivacaftor treatment. P aeruginosa prevalence decreased to a similar extent in both male and female patients after ivacaftor treatment.

INTERPRETATION

Our findings demonstrate that sex disparities in CF persist in those treated with ivacaftor because of differences in pulmonary exacerbations. More research is needed to determine the specific pathophysiologic drivers of this disparity.

Effect of Modulator Therapies on Nutritional Risk Index in Adults with Cystic Fibrosis: A Prospective Cohort Study

Background: Modulator therapies improve weight and body mass index (BMI) in cystic fibrosis (CF) patients. We aimed to compare the nutritional risk index (NRI) in adult CF patients receiving modulator (MT) or only non-modulator (conventional) therapies (non-MT). Methods: A single-center prospective cohort study was conducted between June and December 2023. The NRI based on weight gain and albumin was calculated at beginning and end of a 12-week period in both groups. This design was pragmatic, since it was based on individual patient access to MT for 12 weeks. Results: In total, 107 patients were included [mean (SD) age: 23.85 (4.98) years, 54.7% male, 46.7% MT]. In the MT group, mean (SD) weight (kg) and albumin (g/dL) increased significantly [changes: +3.09 (2.74) and +0.17 (0.37); p < 0.001]. In the non-MT group, weight and albumin decreased significantly [changes: -0.99 (1.73) and -0.12 (0.30); p < 0.001]. Compared to the MT group, baseline mean (SD) NRI in the non-MT group was significantly higher [100.65 (11.80) vs. 104.10 (10.10); p = 0.044]. At the end of the 12 weeks, mean (SD) NRI in the MT group was higher than in the non-MT group [104.18 (10.40) vs. 102.58 (12.39); p = 0.145]. In the MT group, the NRI category improved in 22 (44%), and worsened in 3 (6%) patients (p < 0.001). In the non-MT group, the NRI category improved in 2 (3.5%), and worsened in 10 (17.5%) patients (p < 0.001). Conclusions: This is the first study reporting on a positive effect of MT on NRIs, based on weight gain and albumin. Personalized nutrition and routine follow-up of adults with CF based on NRI is recommended prior to MT initiation.

Highly effective cystic fibrosis transmembrane conductance (regulator) modulator therapy: shifting the curve for most while leaving some further behind

PURPOSE OF REVIEW

Traditional cystic fibrosis (CF) care had been focused on early intervention and symptom mitigation. With the advent of highly effective cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy (HEMT), in particular, the approval of elexacaftor/tezacaftor/ivacaftor in 2019, there has been a dramatic improvement in outcomes in CF. The purpose of this article is to review the benefits, limitations, and impact of HEMT as well as discuss the new implications, challenges, and hope that modulators bring to people with CF (pwCF).

RECENT FINDINGS

HEMT has demonstrated sustained improvement in lung function, nutrition, quality of life, and survival for over 90% of pwCF. As HEMT has delivered such promise, there is a small but significant portion of pwCF who do not benefit from HEMT due to ineligible mutations, intolerance, or lack of accessibility to modulators.

SUMMARY

HEMT has significantly improved outcomes, but continued research is needed to understand the new challenges and implications the era of HEMT will bring, as well as how to provide equitable care to those who are unable to benefit from HEMT.

Elexacaftor-tezacaftor-ivacaftor decreases pseudomonas abundance in the sinonasal microbiome in cystic fibrosis

BACKGROUND

Chronic rhinosinusitis (CRS) is common in individuals with cystic fibrosis (CF) and is marked by chronic inflammation and episodes of infection that negatively impact quality of life. Several studies have shown that elexacaftor-tezacaftor-ivacaftor (ETI) improves symptoms and examination findings in CF-CRS. The current study determines the effect of ETI on the sinonasal microbiota in CF.

METHODS

Sinonasal samples were collected under endoscopic visualization before and after starting ETI. Samples were subjected to 16S amplicon sequencing and sequences were processed with the QIIME2 pipeline with subsequent analysis using the vegan R-package.

RESULTS

Twenty-nine individual baseline samples and 23 sample pairs pre-/post-ETI were available. At baseline, the cohort had samples dominated by Staphylococcus, and alpha diversity was lower than that of a published reference set of individuals without sinonasal disease. Individuals with prior sinus surgery had lower alpha diversity as measured by Shannon Index, Observed Richness, and Faith's phylogenetic diversity Index. Beta diversity differed between individuals with and without allergic rhinitis, with higher Staphylococcus abundance in those with allergic rhinitis. No change in alpha or beta diversity was seen after a median of 9 months on ETI. With ETI, the Pseudomonas genus and the genus containing Burkholderia decreased in samples containing these taxa at baseline. Pseudomonas abundance decreased with treatment as measured by qPCR. Core sinonasal microbiome members Staphylococcus, Corynebacterium, and Streptococcus were unchanged, while Moraxella increased with ETI.

CONCLUSIONS

Treatment with ETI leads to a reduction in Pseudomonas abundance within the sinonasal microbiome of individuals with Pseudomonas at baseline.

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.

Preservation of β-cell Function in Pancreatic Insufficient Cystic Fibrosis With Highly Effective CFTR Modulator Therapy

CONTEXT

Elexacaftor/tezacaftor/ivacaftor (ETI; Trikafta) enhances aberrant cystic fibrosis transmembrane conductance regulator function and may improve the insulin secretory defects associated with a deterioration in clinical outcomes in pancreatic insufficient cystic fibrosis (PI-CF).

OBJECTIVE

This longitudinal case-control study assessed changes in β-cell function and secretory capacity measures over 2 visits in individuals with PI-CF who were initiated on ETI after the baseline visit (2012-2018) and (1) restudied between 2019 and 2021 (ETI group) vs (2) those restudied between 2015 and 2018 and not yet treated with cystic fibrosis transmembrane conductance regulator modulator therapy (controls).

METHODS

Nine ETI participants (mean ± SD age, 25 ± 5 years) and 8 matched controls were followed up after a median (interquartile range) 5 (4-7) and 3 (2-3) years, respectively (P < .01), with ETI initiation a median of 1 year before follow-up. Clinical outcomes, glucose-potentiated arginine, and mixed-meal tolerance test measures were assessed with comparisons of within- and between-group change by nonparametric testing.

RESULTS

Glucose-potentiated insulin and C-peptide responses to glucose-potentiated arginine deteriorated in controls but not in the ETI group, with C-peptide changes different between groups (P < .05). Deterioration in basal proinsulin secretory ratio was observed in controls but improved, as did the maximal arginine-induced proinsulin secretory ratio, in the ETI group (P < .05 for all comparisons). During mixed-meal tolerance testing, early insulin secretion improved as evidenced by more rapid insulin secretory rate kinetics.

CONCLUSION

ETI preserves β-cell function in CF through effects on glucose-dependent insulin secretion, proinsulin processing, and meal-related insulin secretion. Further work should determine whether early intervention with ETI can prevent deterioration of glucose tolerance in PI-CF.

Use of adenine base editing and homology-independent targeted integration strategies to correct the cystic fibrosis causing variant, W1282X

Small molecule drugs known as modulators can treat ~90% of people with cystic fibrosis (CF), but do not work for premature termination codon variants such as W1282X (c.3846G>A). Here we evaluated two gene editing strategies, Adenine Base Editing (ABE) to correct W1282X, and Homology-Independent Targeted Integration (HITI) of a CFTR superexon comprising exons 23-27 (SE23-27) to enable expression of a CFTR mRNA without W1282X. In Flp-In-293 cells stably expressing a CFTR expression minigene bearing W1282X, ABE corrected 24% of W1282X alleles, rescued CFTR mRNA from nonsense mediated decay and restored protein expression. However, bystander editing at the adjacent adenine (c.3847A>G), caused an amino acid change (R1283G) that affects CFTR maturation and ablates ion channel activity. In primary human nasal epithelial cells homozygous for W1282X, ABE corrected 27% of alleles, but with a notably lower level of bystander editing, and CFTR channel function was restored to 16% of wild-type levels. Using the HITI approach, correct integration of a SE23-27 in intron 22 of the CFTR locus in 16HBEge W1282X cells was detected in 5.8% of alleles, resulting in 7.8% of CFTR transcripts containing the SE23-27 sequence. Analysis of a clonal line homozygous for the HITI-SE23-27 produced full-length mature protein and restored CFTR anion channel activity to 10% of wild-type levels, which could be increased three-fold upon treatment with the triple combination of CF modulators. Overall, these data demonstrate two different editing strategies can successfully correct W1282X, the second most common class I variant, with a concomitant restoration of CFTR function.

Chronic daily respiratory care needs in people with cystic fibrosis treated with highly effective cystic fibrosis transmembrane conductance regulator modulators

PURPOSE OF REVIEW

Cystic fibrosis is a genetic disease that increases risk of death from respiratory failure because of impairment in mucociliary clearance. Complex daily care regimens including medications and airway clearance techniques (ACTs) aim to preserve lung function and alleviate symptoms for people with cystic fibrosis (pwCF). The success of highly effective modulator therapy (HEMT) permits evaluation of treatment simplification. In this review, we evaluate adjustments made in daily respiratory care among pwCF taking HEMT and the feasibility of treatment simplification.

RECENT FINDINGS

Treatment simplification has been identified as a top priority among pwCF, with recent studies showing pwCF are willing to sacrifice mild to moderate amounts of lung function and longevity to reduce treatment burden. Retrospective studies have shown that patients taking HEMT with better baseline lung function have lower adherence to and prescription of inhaled medications. A randomized, controlled trial found that short-term discontinuation of dornase alfa or hypertonic saline was clinically noninferior to continuation of these medications. Major knowledge gaps remain about withdrawing ACTs.

SUMMARY

This review highlights trials evaluating the feasibility of treatment simplification among pwCF taking HEMT. More data is needed to evaluate approaches to simplification in this phenotypically diverse patient population.

Delivering a New Future for People With Cystic Fibrosis

Treatment, prognosis, and quality of life for people with cystic fibrosis (CF) have improved steadily since the initial description of the disease, but most dramatically in the past decade. In 2021, the median predicted survival increased to 53 years, compared with 17 years in 1970. The recent improvement in outcomes is attributable to the advent of cystic fibrosis transmembrane regulator (CFTR) modulators, small molecules that enhance the function of defective CFTR protein. The first CFTR modulator, ivacaftor, received Food and Drug Administration approval in 2011 to treat a single CFTR variant, comprising only 4% of those affected by CF. With the demonstration of efficacy, drug approval has been expanded to other variants. Multiple CFTR modulators used in combination with ivacaftor augment efficacy and increase the number of CFTR variants amenable to therapy. Approval of elexecaftor/tezecaftor/ivacaftor in 2019 increased the number of individuals who could benefit from highly effective modulator therapy (HEMT) to ∼90% of the CF population in the United States. HEMT has been dramatically effective, with overall improvements in lung function, quality of life, nutritional status, and, in women, increased fertility. HEMT may delay the onset of other CF-related comorbidities. Although off-target effects, including hepatotoxicity, drug-drug interactions, and putative mental health issues can complicate use, modulator therapy has been generally well tolerated. Ten percent of people with CF have variants that are not amenable to modulator treatment. HEMT, despite its great cost and limited global access, has brought legitimate hope and changed the lives of a significant majority of individuals and families affected by CF in North America.

Nutritional management of people living with cystic fibrosis throughout life and disease continuum: Changing times, new challenges

Cystic fibrosis (CF) is a genetic disease caused by mutations in the gene encoding for the ion channel cystic fibrosis transmembrane conductance regulator (CFTR). The management of CF disease has evolved in recent decades from treating downstream disease manifestations affecting the airways, the lungs and the gastrointestinal system to addressing the CFTR gene defect. The advent of CFTR modulators, which correct the functionality of the defective CFTR, contributes to reshaping the landscape of CF demographics, prognosis and therapies, including nutritional management. A spectrum of clinical manifestations is emerging within the same patient population where undernutrition and nutritional deficiencies coexist with excessive weight gain and metabolic derangements. Such contrasting presentations challenge current practices, require adjustments to traditional approaches, and involve more individualised interventions. This narrative review examines the current state of knowledge on the nutritional management of people living with cystic fibrosis from early life to adulthood in the era of CFTR modulation.

Association of Pseudomonas aeruginosa infection stage with lung function trajectory in children with cystic fibrosis

BACKGROUND

Pseudomonas aeruginosa (Pa) infection in cystic fibrosis (CF) is characterized in stages: never (prior to first positive culture) to incident (first positive culture) to chronic. The association of Pa infection stage with lung function trajectory is poorly understood and the impact of age on this association has not been examined. We hypothesized that FEV1 decline would be slowest prior to Pa infection, intermediate after incident infection and greatest after chronic Pa infection.

METHODS

Participants in a large US prospective cohort study diagnosed with CF prior to age 3 contributed data through the U.S. CF Patient Registry. Cubic spline linear mixed effects models were used to evaluate the longitudinal association of Pa stage (never, incident, chronic using 4 different definitions) with FEV1 adjusted for relevant covariates. Models contained interaction terms between age and Pa stage.

RESULTS

1,264 subjects born 1992-2006 provided a median 9.5 (IQR 0.25 to 15.75) years of follow up through 2017. 89% developed incident Pa; 39-58% developed chronic Pa depending on the definition. Compared to never Pa, incident Pa infection was associated with greater annual FEV1 decline and chronic Pa infection with the greatest FEV1 decline. The most rapid FEV1 decline and strongest association with Pa infection stage was seen in early adolescence (ages 12-15).

CONCLUSIONS

Annual FEV1 decline worsens significantly with each Pa infection stage in children with CF. Our findings suggest that measures to prevent chronic infection, particularly during the high-risk period of early adolescence, could mitigate FEV1 decline and improve survival.

Current and Future Therapeutic Approaches of Exocrine Pancreatic Insufficiency in Children with Cystic Fibrosis in the Era of Personalized Medicine

This review presents current updates of pancreatic enzyme replacement therapy in children with cystic fibrosis based on literature published in the last decade and some special considerations regarding pancreatic enzyme replacement therapy in the era of new therapies, such as cystic fibrosis transmembrane conductance regulator modulator therapies. Few articles evaluate the efficacy of pancreatic enzyme replacement therapy in the pediatric population, and most studies also included children and adults with cystic fibrosis. Approximately 85% of cystic fibrosis patients have exocrine pancreatic insufficiency and need pancreatic enzyme replacement therapy. Fecal elastase is the most commonly used diagnostic test for exocrine pancreatic insufficiency, although this value can fluctuate over time. While it is used as a diagnostic test, it cannot be used for monitoring the effectiveness of pancreatic enzyme replacement therapy and for adjusting doses. Pancreatic enzyme replacement therapy, the actual treatment for exocrine pancreatic insufficiency, is essential in children with cystic fibrosis to prevent malabsorption and malnutrition and needs to be urgently initiated. This therapy presents many considerations for physicians, patients, and their families, including types and timing of administration, dose monitoring, and therapy failures. Based on clinical trials, pancreatic enzyme replacement therapy is considered effective and well-tolerated in children with cystic fibrosis. An important key point in cystic fibrosis treatment is the recent hypothesis that cystic fibrosis transmembrane conductance regulator modulators could improve pancreatic function, further studies being essential. Pancreatic enzyme replacement therapy is addressed a complication of the disease (exocrine pancreatic insufficiency), while modulators target the defective cystic fibrosis transmembrane conductance regulator protein. Exocrine pancreatic insufficiency in cystic fibrosis remains an active area of research in this era of cystic fibrosis transmembrane conductance regulator modulator therapies. This new therapy could represent an example of personalized medicine in cystic fibrosis patients, with each class of modulators being addressed to patients with specific genetic mutations.

Nutritional impact of CFTR modulators in children with cystic fibrosis

Background

Nutritional status is a major prognostic factor for breathing and the survival of patients with cystic fibrosis (CF). Since 2012, the development of CFTR modulators has considerably transformed the outcome of this disease. Indeed, both lung function and body mass index are improved by CFTR modulators, such as Lumacaftor/Ivacaftor. However, few data exist regarding the outcome of nutritional intakes under Lumacaftor/Ivacaftor.

Methods

We conducted a prospective single-center study in children with CF treated with Lumacaftor/Ivacaftor to evaluate their nutritional intake before and after treatment.

Results

Thirty-four children were included in this study, with a median age of 12.4 years [11.9; 14.7]. There was no significant improvement in weight, height or BMI. Patients' total energy intake was not significantly changed with Lumacaftor/Ivacaftor, while carbohydrate intakes decreased significantly. We found that blood levels of vitamin E and Selenium were significantly increased under Lumacaftor/Ivacaftor, without a significant increase in supplementation. In patients with a BMI Z-score < 0 at treatment initiation, there was a significant improvement in weight and BMI Z-score, while TEI and carbohydrate intakes were significantly lower.

Conclusion

We showed that treatment with Lumacaftor/Ivacaftor improved the nutritional status of patients without necessarily being associated with an increase in nutritional intake. Although these data need to be confirmed in larger cohorts, they support the hypothesis that weight gain under modulators is multifactorial, and may be related to a decrease in energy expenditure or an improvement in absorption.

VOCAL: An observational study of ivacaftor for people with cystic fibrosis and selected non-G551D-CFTR gating mutations

BACKGROUND

VOCAL was an observational study of the effect of long-term ivacaftor on real-world clinical outcomes and healthcare resource utilization (HCRU) in people with cystic fibrosis (pwCF) in Italy, the Netherlands, and the UK.

METHODS

pwCF aged ≥6 years with non-G551D-CFTR gating mutations were eligible. Prospective data were collected up to 48 months after enrollment; retrospective data were collected to ensure that 12 months of pre-ivacaftor data were available. Endpoints included absolute change from baseline in percent predicted forced expiratory volume in 1 second (ppFEV₁) and measures of nutritional status. Pulmonary exacerbation (PEx) rates, HCRU, and respiratory microbiology during ivacaftor treatment were compared with data from the 12-month period before initiation.

RESULTS

Seventy-three eligible pwCF were enrolled and received ivacaftor; 65 (89.0%) completed the study (48 [65.8%] completed ≥48 months of ivacaftor). During the first 6 months of ivacaftor, ppFEV₁, body mass index (BMI), and BMI-for-age z-score showed least-squares mean absolute improvements of 10.8 percentage points, 0.79 kg/m², and 0.54, respectively; improvements were maintained through 48 months. Rates of PEx, antibiotic use due to PEx, and hospitalization decreased by >50% during ivacaftor treatment compared with before ivacaftor. The number of respiratory cultures and sputum was lower post-ivacaftor, as was the percentage of pwCF with positive respiratory cultures for 3 of 9 pathogens evaluated (Pseudomonas aeruginosa, Aspergillus fumigatus, Stenotrophomonas maltophilia). Reported safety results were consistent with CF and ivacaftor's known safety profile.

CONCLUSIONS

These results demonstrate the positive long-term effectiveness of ivacaftor on clinical outcomes and HCRU in pwCF with non-G551D-CFTR gating mutations in real-world settings.

Characterizing CFTR modulated sweat chloride response across the cf population: Initial results from the CHEC-SC study

BACKGROUND

CHEC-SC is an ongoing epidemiologic study characterizing modulator-induced sweat chloride (SC) responses across the CF population, with interim results available prior to the availability of triple combination modulator therapy.

METHODS

Eligible participants had been prescribed a modulator for ≥90 days with re-enrollment allowed upon establishment of a new modulator. Pre-modulator SC values were obtained from chart review; post-modulator sweat was collected and analyzed locally. SC changes were descriptively summarized with biologic sex effects adjusted for age, weight, and CFTR genotype. Heterogeneity in ivacaftor SC response was characterized in relation to published CFTR functional responses.

RESULTS

1848 participants provided 2004 SC measurements, 26.2% on ivacaftor, 39.1% on lumacaftor/ivacaftor, and 34.7% on tezacaftor/ivacaftor. Average SC changes for all modulators were consistent with those reported in previous clinical studies, with greater variation in SC response observed among rarer mutations and notable shifts in the proportion with SC <60mmol/L independent of the magnitude of SC change. Ivacaftor induced in vitro CFTR functional change was significantly correlated with ivacaftor-modulated SC response (Pearson correlation= ‒0.52, 95% CI: ‒0.773, ‒0.129). Average SC change from ivacaftor to tezacaftor/ivacaftor was ‒4.9 mmol/L (n=17,95% CI:‒9.3, ‒0.5) and differed from those switching from lumacaftor/ivacaftor (10.0 mmol/L, n=139, 95% CI:7.8,12.3). Sex at birth was not associated with SC response.

CONCLUSIONS

CHEC-SC is the largest study characterizing modulator-induced SC changes across the CF population. There was a strong association between ivacaftor induced in vitro CFTR function and SC response across a genotypically heterogenous cohort. Biological sex was not associated with SC response.

Toward a Broader Understanding of Cystic Fibrosis Epidemiology and Its Impact on Clinical Manifestations

The incidence of cystic fibrosis remains constant in North America and Western Europe is 1 in 3500 live births, but survival and quality of life have improved. The cystic fibrosis population has shifted toward the adult age range with a concomitant shift in the spectrum of complications. Survival increased because of aggressive symptomatic therapy, earlier diagnosis by newborn screening, and the introduction of modulators of the cystic fibrosis transmembrane conductance regulator, so that predicted median survival age is now about 50 years. In the United States, members of low socioeconomic status populations or members of racial or ethnic minorities have benefitted less from these advances.

Update on Clinical Outcomes of Highly Effective Modulator Therapy

Based on the cystic fibrosis transmembrane conductance regulator (CFTR) genotype, approximately 90% of people with cystic fibrosis (CF) are candidates for highly effective modulator therapy (HEMT). Clinical trials conducted over the last 11 years have shown that these oral therapies substantially restore CFTR function, leading to improvements in lung function, nutritional status, and health-related quality of life. Here, we review safety and efficacy data from phase 3 clinical trials and observational studies which support the use of HEMT in most adults and children with CF. We also discuss opportunities for additional investigation in groups underrepresented or excluded from phase 3 clinical trials, and challenges in the evaluation of the safety and efficacy of HEMT at increasingly earlier stages of CFTR-mediated pathophysiology.

Plasma and cellular ivacaftor concentrations in patients with cystic fibrosis

Access to cystic fibrosis transmembrane conductance regulator (CFTR) modulators has been gradually increasing for people with cystic fibrosis, the first of which was ivacaftor, a CFTR potentiator that is part of all clinically available modulator treatments. In this study, we hypothesized that the steady-state concentrations in blood and tissue are highly variable in patients taking ivacaftor in a real-world context, which may have an impact on the treatment approach. We collected nasal epithelial cells to estimate target site concentrations and blood samples to estimate pharmacokinetic parameters at a steady state. We found that patients on ivacaftor monotherapy have variable concentrations well above the maximal effective concentration and may maintain concentrations necessary for the clinical benefit even if dosing is reduced. We also are the first to provide detailed target site concentration data over time, which shows that tissue concentrations do not fluctuate significantly and do not correlate with plasma concentrations. These findings show that some patients may have higher-than-expected concentrations and may benefit from tailored dosing to balance clinical response with side effects or adherence needs.

Drugs, Drugs, Drugs: Current Treatment Paradigms in Cystic Fibrosis Airway Infections

Airway infections have remained a prominent feature in persons living with cystic fibrosis (CF) despite the dramatic improvements in survival in the past decades. Antimicrobials are a cornerstone of infection management for both acute and chronic maintenance indications. Historic clinical trials of antimicrobials in CF have led to the adoption of consensus guidelines for their use in clinical care. More recently, however, there are efforts to re-think the optimal use of antimicrobials for care with the advent of novel and highly effective CF transmembrane conductance regulator modulator therapies. Encouragingly, however, drug development has remained active concurrently in this space. Our review focuses on the evidence for and perspectives regarding antimicrobial use in both acute and maintenance settings in persons with CF. The therapeutic innovations in CF and how this may affect antimicrobial approaches are also discussed.

Cystic fibrosis year in review 2021

People with cystic fibrosis (CF) have an amazing outlook with the treatment availability of highly effective modulators. Unfortunately, not all people with CF are eligible for modulators leading to continued pulmonary exacerbations and advanced lung disease. Additionally, optimizing diagnosis and evaluation for CF in the newborn period continues to be an area of focus for research. This review article will work to cover articles published in 2021 with high clinical relevance related to the above topics; however, due to the extensive body of research published, this review will not be comprehensive.

Left behind: The potential impact of CFTR modulators on racial and ethnic disparities in cystic fibrosis

The advent of CFTR modulators, a genomic specific medication, revolutionized the treatment of CF for many patients. However, given that these therapeutics were only developed for specific CFTR mutations, not all people with CF have access to such disease-modifying drugs. Racial and ethnic minority groups are less likely to have CFTR mutations that are approved for CFTR modulators. This exclusion has the potential to widen existing health disparities.

“Acquiring the Skills Needed to Communicate What Is in Our Teams’ Heart: Love, Compassion and Partnership”: Qualitative Analysis of Intact Multidisciplinary Teams’ Experience of Relationship-Centered Communication Training

The Partnership Enhancement Program (PEP) is a 6-hour relationship-centered communication training for intact cystic fibrosis (CF) teams. The aim of this study was to analyze qualitative responses from survey participants regarding their takeaways from the training. A total of 210 professionals participated in 20 pilot workshops at 19 care centers in the United States from November 2018 to December 2019. After the workshop, qualitative feedback was captured by PEP facilitators during a feedback gathering session or submitted immediately in writing by participants. The manuscript team used grounded theory and qualitative methods of coding to identify recurring themes across participant responses. Thematic analysis revealed 5 primary themes and a web of interconnected subthemes. Primary themes include the acquisition of skills to improve communication, strengthened patient/provider connection, improved quality of communication, improved team building, and the ability to change and enhance practice. Participants who completed PEP training endorse acquiring communication skills that increase coproduction of care with patients and caregivers as well as improve relationships across the healthcare system.

CFTR Modulator Therapies: Potential Impact on Airway Infections in Cystic Fibrosis

Cystic Fibrosis (CF) is an autosomal recessive disease caused by mutations in the gene encoding for the Cystic Fibrosis Transmembrane conductance Regulator (CFTR) protein, expressed on the apical surface of epithelial cells. CFTR absence/dysfunction results in ion imbalance and airway surface dehydration that severely compromise the CF airway microenvironment, increasing infection susceptibility. Recently, novel therapies aimed at correcting the basic CFTR defect have become available, leading to substantial clinical improvement of CF patients. The restoration or increase of CFTR function affects the airway microenvironment, improving local defence mechanisms. CFTR modulator drugs might therefore affect the development of chronic airway infections and/or improve the status of existing infections in CF. Thus far, however, the full extent of these effects of CFTR-modulators, especially in the long-term remains still unknown. This review aims to provide an overview of current evidence on the potential impact of CFTR modulators on airway infections in CF. Their role in affecting CF microbiology, the susceptibility to infections as well as the potential efficacy of their use in preventing/decreasing the development of chronic lung infections and the recurrent acute exacerbations in CF will be critically analysed.

The Changing Landscape of Nutrition in Cystic Fibrosis: The Emergence of Overweight and Obesity

Cystic fibrosis has historically been characterized by malnutrition, and nutrition strategies have placed emphasis on weight gain due to its association with better pulmonary outcomes. As treatment for this disease has significantly improved, longevity has increased and overweight and obesity have emerged issues in this population. The effect of excess weight and adiposity on CF clinical outcomes is unknown but may produce similar health consequences and obesity-related diseases as those observed in the general population. This review examines the prevalence of overweight and obesity in CF, the medical and psychological impact, as well as the existing evidence for treatment in the general population and how this may be applied to people with CF. Clinicians should partner with individuals with CF and their families to provide a personalized, interdisciplinary approach that includes dietary modification, physical activity, and behavioral intervention. Additional research is needed to identify the optimal strategies for preventing and addressing overweight and obesity in CF.

Precision Medicine Based on CFTR Genotype for People with Cystic Fibrosis

Cystic fibrosis (CF) is an autosomal recessive genetic condition that is caused by variants in the cystic fibrosis transmembrane conductance regulator gene. This causes multisystem disease due to dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) ion channel at the apical surface of epithelia. Until recently, treatment was directed at managing the downstream effects in affected organs, principally improving airway clearance and treating infection in the lungs and improving malabsorption in the gastrointestinal tract. Care delivered by multidisciplinary teams has yielded incremental improvements in outcomes. However, the development of small-molecule CFTR modulator drugs over the last decade has heralded a new era of CF therapeutics. Modulators target the underlying defect and improve CFTR function. Either monotherapy or a combination of modulators is used depending on the specific genotype and class of CFTR disease-causing variants that an individual has. Both ivacaftor and the ivacaftor/tezacaftor/elexacaftor combination have been demonstrated to be associated with clinically very significant benefits in randomised trials and have rapidly been made available as part of standard care in many countries. CFTR modulators represent one of the best examples of precision medicine to date. They are expensive, however, and equity of access to them worldwide remains an issue. Studies and approvals are also ongoing for children under the age of 6 years for ivacaftor/tezacaftor/elexacaftor. Furthermore, no modulators are available for around 10% of the people with CF. In this review, we firstly summarise the genetics, pathophysiology and clinical problems associated with CF. We then discuss the development of CFTR modulators and key clinical trials to support their use along with other potential future therapeutic approaches.

Increasing life expectancy in cystic fibrosis: Advances and challenges

Since the first description of cystic fibrosis in 1938, there have been significant advances in both quality of life and longevity for people living with this disease. In this article we describe the milestones of the last 80 years and what we perceive to be the remaining barriers to normalcy for this population.

The Relationship between Body Composition, Dietary Intake, Physical Activity, and Pulmonary Status in Adolescents and Adults with Cystic Fibrosis

Measures of body fat and lean mass may better predict important clinical outcomes in patients with cystic fibrosis (CF) than body mass index (BMI). Little is known about how diet quality and exercise may impact body composition in these patients. Dual X-ray absorptiometry (DXA) body composition, 24-h dietary recall, and physical activity were assessed in a cross-sectional analysis of 38 adolescents and adults with CF and 19 age-, race-, and gender-matched healthy volunteers. Compared with the healthy volunteers, participants with CF had a lower appendicular lean mass index (ALMI), despite no observed difference in BMI, and their diets consisted of higher glycemic index foods with a greater proportion of calories from fat and a lower proportion of calories from protein. In participants with CF, pulmonary function positively correlated with measures of lean mass, particularly ALMI, and negatively correlated with multiple measures of body fat after controlling for age, gender, and BMI. Higher physical activity levels were associated with greater ALMI and lower body fat. In conclusion, body composition measures, particularly ALMI, may better predict key clinical outcomes in individuals with CF than BMI. Future longitudinal studies analyzing the effect of dietary intake and exercise on body composition and CF-specific clinical outcomes are needed.

Effects of Elexacaftor/Tezacaftor/Ivacaftor Therapy on CFTR Function in Patients with Cystic Fibrosis and One or Two F508del Alleles

RATIONALE

The CFTR modulator combination elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) was shown to improve clinical outcomes and sweat chloride concentration (SCC) in patients with cystic fibrosis (CF) and one or two F508del alleles. However, the effect of ELX/TEZ/IVA on CFTR function in the airways and intestine has not been studied.

OBJECTIVES

To assess the effect of ELX/TEZ/IVA on CFTR function in airway and intestinal epithelia in patients with CF and one or two F508del alleles aged 12 years and older.

METHODS

This prospective observational multicenter study assessed clinical outcomes including FEV1 %predicted and body mass index, and the CFTR biomarkers SCC, nasal potential difference (NPD) and intestinal current measurement (ICM) before and 8-16 weeks after initiation of ELX/TEZ/IVA.

MEASUREMENTS AND MAIN RESULTS

A total of 107 patients with CF including 55 patients with one F508del and a minimal function mutation and 52 F508del homozygous patients were enrolled in this study. In patients with one F508del allele, NPD and ICM showed that ELX/TEZ/IVA improved CFTR function in nasal epithelia to a level of 46.5% (IQR, 27.5-72.4; P<0.001) and in intestinal epithelia to 41.8% of normal (IQR, 25.1-57.6; P<0.001). In F508del homozygous patients, ELX/TEZ/IVA exceeded improvement of CFTR function observed with TEZ/IVA and increased CFTR-mediated Cl- secretion to a level of 47.4% of normal (IQR, 19.3-69.2; P<0.001) in nasal and to 45.9% (IQR, 19.7-66.6; P<0.001) in intestinal epithelia.

CONCLUSIONS

Treatment with ELX/TEZ/IVA results in effective improvement of CFTR function in airway and intestinal epithelia in patients with CF and one or two F508del alleles.

Clinical Effectiveness of Elexacaftor/Tezacftor/Ivacaftor in People with Cystic Fibrosis

Rationale

The cystic fibrosis (CF) modulator drug, elexacaftor/tezacaftor/ivacaftor (ETI), proved highly effective in controlled clinical trials for individuals with at least one F508del allele, which occurs in at least 85% of people with CF.

Objectives

PROMISE is a postapproval study to understand the broad effects of ETI through 30 months’ clinical use in a more diverse U.S. patient population with planned analyses after 6 months.

Methods

Prospective, observational study in 487 people with CF age 12 years or older with at least one F508del allele starting ETI for the first time. Assessments occurred before and 1, 3, and 6 months into ETI therapy. Outcomes included change in percent predicted FEV₁ (ppFEV₁), sweat chloride concentration, body mass index (BMI), and self-reported respiratory symptoms.

Measurements and Main Results

Average age was 25.1 years, and 44.1% entered the study using tezacaftor/ivacaftor or lumacaftor/ivacaftor, whereas 6.7% were using ivacaftor, consistent with F508del homozygosity and G551D allele, respectively. At 6 months into ETI therapy, ppFEV₁ improved 9.76 percentage points (95% confidence interval [CI], 8.76 to 10.76) from baseline, cystic fibrosis questionnaire–revised respiratory domain score improved 20.4 points (95% CI, 18.3 to 22.5), and sweat chloride decreased −41.7 mmol/L (95% CI, −43.8 to −39.6). BMI also significantly increased. Changes were larger in those naive to modulators but substantial in all groups, including those treated with ivacaftor at baseline.

Conclusions

ETI by clinical prescription provided large improvements in lung function, respiratory symptoms, and BMI in a diverse population naive to modulator drug therapy, using existing two-drug combinations, or using ivacaftor alone. Each group also experienced significant reductions in sweat chloride concentration, which correlated with improved ppFEV₁ in the overall study population.

Clinical trial registered with www.clinicaltrials.gov (NCT NCT04038047).

Real-World Long-Term Ivacaftor for Cystic Fibrosis in France: Clinical Effectiveness and Healthcare Resource Utilization

Introduction

Ivacaftor is a cystic fibrosis transmembrane conductance regulator (CFTR) potentiator that has demonstrated clinical benefits in phase 3 trials. We report results from a real-world study (BRIO) to assess the effectiveness of ivacaftor in people with cystic fibrosis (pwCF) in France.

Methods

BRIO was an observational study conducted at 35 centers in France. Both pwCF initiating ivacaftor treatment and those already taking ivacaftor were included and prospectively followed for 24 months. The primary objective was to evaluate the effect of ivacaftor on percent predicted forced expiratory volume in 1 s (ppFEV₁); secondary objectives were evaluating the effect of ivacaftor on clinical effectiveness, healthcare resource utilization (HCRU), and safety.

Results

A total of 129 pwCF were enrolled; 58.9% were aged < 18 years; 64.3% had a G551D-CFTR allele. Mean age at ivacaftor initiation was 19.1 years (range, 2–64 years); ppFEV₁ increased by a least squares mean of 8.49 percentage points in the first 6 months and was sustained through 36 months of ivacaftor use. Growth metrics increased during the first 12 months post-ivacaftor and remained stable. The rate of pulmonary exacerbations (PEx) decreased during the 12 months post-ivacaftor compared with the 12 months pre-ivacaftor; estimated rate ratios (95% CI) were 0.57 (0.43–0.75) for PEx events and 0.25 (0.13–0.48) for PEx requiring hospitalization. No new safety concerns were identified; no deaths occurred.

Conclusions

The results from this real-world study of ivacaftor usage in France were consistent with prior clinical trial outcomes, confirming the clinical effectiveness of ivacaftor, as well as an associated reduction in HCRU.

Supplementary Information

The online version contains supplementary material available at 10.1007/s41030-021-00158-5.

New Therapies to Correct the Cystic Fibrosis Basic Defect

Rare diseases affect 400 million individuals worldwide and cause significant morbidity and mortality. Finding solutions for rare diseases can be very challenging for physicians and researchers. Cystic fibrosis (CF), a genetic, autosomal recessive, multisystemic, life-limiting disease does not escape this sad reality. Despite phenomenal progress in our understanding of this disease, treatment remains difficult. Until recently, therapies for CF individuals were focused on symptom management. The discovery of the cystic fibrosis transmembrane conductance regulator (CFTR) gene and its product, a protein present at the apical surface of epithelial cells regulating ion transport, allowed the scientific community to learn about the basic defect in CF and to study potential therapies targeting the dysfunctional protein. In the past few years, promising therapies with the goal to restore CFTR function became available and changed the lives of several CF patients. These medications, called CFTR modulators, aim to correct, potentialize, stabilize or amplify CFTR function. Furthermore, research is ongoing to develop other targeted therapies that could be more efficient and benefit a larger proportion of the CF community. The purpose of this review is to summarize our current knowledge of CF genetics and therapies restoring CFTR function, particularly CFTR modulators and gene therapy.

A new era for people with cystic fibrosis

Cystic fibrosis is the most prevalent inherited disease caused by a defect in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The impaired electrolyte homeostasis caused by the mutated or absent protein leads to symptoms in multiple organ systems. However, the pulmonary manifestation with chronic infections and eventually respiratory failure remains the most important threat. Until one decade ago, only symptomatic treatment was available. However, since 2012, different combinations of CFTR modulators are available for people with cystic fibrosis (pwCF) that carry different mutations. The advent of these drugs has impressively changed life expectancy and quality of life in people with cystic fibrosis and raised new challenges regarding long-term complications and tapering of conventional therapies.Conclusion: In this review, we provide an update on the latest developments around diagnostics, treatment, and prognosis of pwCF. What is Known: • Cystic fibrosis is an incurable and life-shortening disease asking for life-long symptomatic treatment. • Three combination CFTR modulating drugs has gained marked approval over the last 10 years. What is New: • The emerge of new (modulating) therapies contribute to the increasing life expectancy. • A high unmet need to develop new therapies for people with CF who cannot access or benefit from these drugs remains. This review gives an update on the current status.