Elexacaftor/tezacaftor/ivacaftor influences body composition in adults with cystic fibrosis: a fully automated CT-based analysis.

A poor nutritional status is associated with worse pulmonary function and survival in people with cystic fibrosis (pwCF). CF transmembrane conductance regulator modulators can improve pulmonary function and body weight, but more data is needed to evaluate its effects on body composition. In this retrospective study, a pre-trained deep-learning network was used to perform a fully automated body composition analysis on chest CTs from 66 adult pwCF before and after receiving elexacaftor/tezacaftor/ivacaftor (ETI) therapy. Muscle and adipose tissues were quantified and divided by bone volume to obtain body size-adjusted ratios. After receiving ETI therapy, marked increases were observed in all adipose tissue ratios among pwCF, including the total adipose tissue ratio (+ 46.21%, p < 0.001). In contrast, only small, but statistically significant increases of the muscle ratio were measured in the overall study population (+ 1.63%, p = 0.008). Study participants who were initially categorized as underweight experienced more pronounced effects on total adipose tissue ratio (p = 0.002), while gains in muscle ratio were equally distributed across BMI categories (p = 0.832). Our findings suggest that ETI therapy primarily affects adipose tissues, not muscle tissue, in adults with CF. These effects are primarily observed among pwCF who were initially underweight. Our findings may have implications for the future nutritional management of pwCF.

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.

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.

Impact of CFTR modulator therapy on body composition as assessed by thoracic computed tomography: A follow-up study.

OBJECTIVE: Treatment with cystic fibrosis transmembrane conductance regulator (CFTR) modulators in individuals with cystic fibrosis (CF) has brought a significant change in forced expiratory volume in 1 second (FEV1) and clinical parameters. However, it also results in weight gain. The aim of our study is to evaluate the effect of CFTR modulator treatment on body composition, measured by computed tomography (CT). METHODS: Adult subjects with CF under follow-up at La Princesa University Hospital were recruited. All of them were on elexacaftor-tezacaftor-ivacaftor (ELX/TEZ/IVA) treatment. Body composition analysis was conducted using CT scans and an open-source software. The results were then compared with bioimpedance estimations, as well as other clinical and spirometry data. RESULTS: Our sample consisted of 26 adult subjects. The fat mass compartments on CT scans correlated with similar compartments on bioimpedance, and normal-density muscle mass exhibited a strong correlation with phase angle. Higher levels of very low-density muscle prior to treatment were associated with lower final FEV1 and less improvement in FEV1 after therapy. We observed an increase in total body area (P < 0.001), driven by increases in total fat mass (P < 0.001), subcutaneous fat (P < 0.001), visceral fat (P = 0.002), and intermuscular fat (P = 0.022). The only muscle compartment that showed an increase after treatment was very low-density muscle (P = 0.032). CONCLUSIONS: CT scans represent an opportunity to assess body composition on CF. Combination treatment with CFTR modulators, leads to an improvement in FEV1 and to an increase in body mass in all compartments primarily at the expense of fat mass.

Persistence and evolution of Pseudomonas aeruginosa following initiation of highly effective modulator therapy in cystic fibrosis.

Today, more than 90% of people with cystic fibrosis (pwCF) are eligible for the highly effective cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy called elexacaftor/tezacaftor/ivacaftor (ETI) and its use is widespread. Given the drastic respiratory symptom improvement experienced by many post-ETI, clinical studies are already underway to reduce the number of respiratory therapies, including antibiotic regimens, that pwCF historically relied on to combat lung disease progression. Early studies suggest that bacterial burden in the lungs is reduced post-ETI, yet it is unknown how chronic Pseudomonas aeruginosa populations are impacted by ETI. We found that pwCF remain infected throughout their upper and lower respiratory tract with their same strain of P. aeruginosa post-ETI, and these strains continue to evolve in response to the newly CFTR-corrected airway. Our work underscores the continued importance of CF airway microbiology in the new era of highly effective CFTR modulator therapy. IMPORTANCE: The highly effective cystic fibrosis transmembrane conductance regulator modulator therapy Elexakaftor/Tezacaftor/Ivacaftor (ETI) has changed cystic fibrosis (CF) disease for many people with cystic fibrosis. While respiratory symptoms are improved by ETI, we found that people with CF remain infected with Pseudomonas aeruginosa. How these persistent and evolving bacterial populations will impact the clinical manifestations of CF in the coming years remains to be seen, but the role and potentially changing face of infection in CF should not be discounted in the era of highly effective modulator therapy.

Year in review 2023 - Back to the future.

This review synthesizes articles published in 2023, focusing on the impact of elexacaftor-tezacaftor-ivacaftor (ETI) in cystic fibrosis (CF) care. Real-world data highlights sustained benefits of ETI across age groups, while challenges like neuropsychological side effects persist. Beyond CFTR modulators, research explores telemedicine and novel therapies. Prioritizing equitable access and addressing unmet needs remain crucial for comprehensive CF management.

Organic Synthesis and Current Understanding of the Mechanisms of CFTR Modulator Drugs Ivacaftor, Tezacaftor, and Elexacaftor.

The monogenic rare disease Cystic Fibrosis (CF) is caused by mutations in the gene encoding the CF transmembrane conductance (CFTR) protein, an anion channel expressed at the apical plasma membrane of epithelial cells. The discovery and subsequent development of CFTR modulators-small molecules acting on the basic molecular defect in CF-have revolutionized the standard of care for people with CF (PwCF), thus drastically improving their clinical features, prognosis, and quality of life. Currently, four of these drugs are approved for clinical use: potentiator ivacaftor (VX-770) alone or in combination with correctors lumacaftor, (VX-809), tezacaftor (VX-661), and elexacaftor (VX-445). Noteworthily, the triple combinatorial therapy composed of ivacaftor, tezacaftor, and elexacaftor constitutes the most effective modulator therapy nowadays for the majority of PwCF. In this review, we exploit the organic synthesis of ivacaftor, tezacaftor, and elexacaftor by providing a retrosynthetic drug analysis for these CFTR modulators. Furthermore, we describe the current understanding of the mechanisms of action (MoA's) of these compounds by discussing several studies that report the key findings on the molecular mechanisms underlying their action on the CFTR protein.

Lumacaftor/Ivacaftor Population Pharmacokinetics in Pediatric Patients with Cystic Fibrosis: A First Step Toward Personalized Therapy.

BACKGROUND: A major breakthrough in cystic fibrosis (CF) therapy was achievedAQ1 with CFTR modulators. The lumacaftor/ivacaftor combination is indicated for the treatment of CF in pediatric patients above 6 years old. Pharmacokinetic (PK) studies of lumacaftor/ivacaftor in these vulnerable pediatric populations are AQ2crucial to optimize treatment protocols. OBJECTIVES AND METHODS: The objectives of this study were to describe the population PK (PPK) of lumacaftor and ivacaftor in children with CF, and to identify factors associated with interindividual variability. The association between drug exposure and clinical response was also investigated. RESULTS: A total of 75 children were included in this PPK study, with 191 concentrations available for each compound and known metabolites (lumacaftor, ivacaftor, ivacaftor-M1, and ivacaftor-M6). PPK analysis was performed using Monolix software. A large interindividual variability was observed. The main sources of interpatient variability identified were patient bodyweight and hepatic function (aspartate aminotransferase). Forced expiratory volume in the first second (FEV1) was statistically associated with the level of exposure to ivacaftor after 48 weeks of treatment. CONCLUSIONS: This study is the first analysis of lumacaftor/ivacaftor PPK in children with CF. These data suggest that dose adjustment is required after identifying variability factors to optimize efficacy. The use of therapeutic drug monitoring as a basis for dose adjustment in children with CF may be useful.

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.

PTI-801 (posenacaftor) shares a common mechanism with VX-445 (elexacaftor) to rescue p.Phe508del-CFTR.

The deletion of a phenylalanine at position 508 (p.Phe508del) in the CFTR anion channel is the most prevalent variant in people with Cystic Fibrosis (CF). This variant impairs folding and stability of the CF transmembrane conductance regulator (CFTR) protein, resulting in its defective trafficking and premature degradation. Over the last years, therapeutic accomplishments have been attained in developing small molecules that partially correct p.Phe508del-CFTR defects; however, the mechanism of action (MoA) of these compounds has only started to be uncovered. In this study, we employed biochemical, fluorescence microscopy, and functional assays to examine the efficacy and properties of PTI-801, a newly developed p.Phe508del-CFTR corrector. To exploit its MoA, we assessed PTI-801 effects in combination with low temperature, genetic revertants of p.Phe508del-CFTR (the in cis p.Val510Asp, p.Gly550Glu, p.Arg1070Trp, and 4RK) and other correctors. Our results demonstrated that PTI-801 rescues p.Phe508del-CFTR processing, PM trafficking, and channel function (upon agonist stimulation) with greater correction effects in combination with ABBV-2222, FDL-169, VX-661, or VX-809, but not with VX-445. Although PTI-801 exhibited no potentiator activity on low temperature- and corrector-rescued p.Phe508del-CFTR, this compound displayed similar behavior to that of VX-445 on genetic revertants. Such evidence associated with the lack of additivity when PTI-801 and VX-445 were combined indicates that they share a common binding site to correct p.Phe508del-CFTR defects. Despite the high efficacy of PTI-801 in combination with ABBV-2222, FDL-169, VX-661, or VX-809, these dual corrector combinations only partially restored p.Phe508del-CFTR conformational stability, as shown by the lower half-life of the mutant protein compared to that of WT-CFTR. In summary, PTI-801 likely shares a common MoA with VX-445 in rescuing p.Phe508del-CFTR, thus being a feasible alternative for the development of novel corrector combinations with greater capacity to rescue mutant CFTR folding and stability.

Lung clearance index (LCI2.5) changes after initiation of Elexacaftor/Tezacaftor/Ivacaftor in children with cystic fibrosis aged between 6 and 11 years: The "real-world" differs from trial data.

BACKGROUND: Elexacaftor in combination with Tezacaftor and Ivacaftor (ETI) became licensed in the United Kingdom in early 2022 for children aged 6-11 years with cystic fibrosis (CF) and an eligible mutation. Many in this age group have excellent prior lung health making quantitative measurement of benefit challenging. Clinical trials purport that lung clearance index (LCI2.5) measurement is most suitable for this purpose. OBJECTIVES: This study aimed to understand the clinical utility of LCI2.5 in detecting change after commencing ETI in the real world. PATIENT SELECTION/METHODS: Baseline anthropometric data were collected along with spirometry (forced expiratory volume in 1 s [FEV1], forced vital capacityFV and LCI2.5 measures in children aged 6-11 years with CF before starting ETI. Measures were repeated after a mean (range) of 8.2 (7-14) months of ETI treatment. The primary endpoint was a change in LCI2.5, with secondary endpoints including change in FEV1 and change in body mass index (BMI) also reported. RESULTS: Twelve children were studied (seven male, mean age 9.5 years at baseline). Our study population had a mean (SD) LCI2.5 of 7.01 (1.14) and FEV1 of 96 (13) %predicted at baseline. Mean (95% confidence interval) changes in LCI2.5 [-0.7 (-1.4, 0), p = .06] and BMI [+0.7 (+0.1, +1.3), p = .03] were observed, along with changes in FEV1 of +3.1 (-1.9, +8.1) %predicted. CONCLUSIONS: Real-world changes in LCI2.5 (-0.7) are different to those reported in clinical trials (-2.29). Lower baseline LCI2.5 as a result of prior modulator exposure, high baseline lung health, and new LCI2.5 software analyses all contribute to lower LCI2.5 values being recorded in the real world of children with CF.

Efficacy of Elexacaftor-Tezacaftor-Ivacaftor on chronic rhinosinusitis in cystic fibrosis.

PURPOSE: Our work aims to add evidence on the effectiveness of Elexacaftor-Tezacaftor-Ivacaftor on chronic rhinosinusitis in cystic fibrosis. MATERIALS AND METHODS: We conducted an observational retrospective cohort study at the Cystic Fibrosis Center of a tertiary care hospital to investigate the effect of Elexacaftor-Tezacaftor-Ivacaftor on chronic rhinosinusitis in cystic fibrosis patients, aged 12 or older. The study's endpoints were the change in the occurrence of acute exacerbations of chronic rhinosinusitis, and the variation of the endoscopic and radiologic findings scored using the Lund-Kennedy endoscopic scale, Lund-Mackay, and modified Lund-Mackay radiologic scales, in patients who underwent both pre-treatment and post-treatment examinations. RESULTS: The study population comprised 136 patients, of which 28 underwent both pre-treatment and post-treatment nasal endoscopy and 15 had pre- and post-treatment CT scans. Elexacaftor-Tezacaftor-Ivacaftor provided a significant improvement in chronic rhinosinusitis. The mean number of acute exacerbations of chronic rhinosinusitis per year in the pre-treatment time was 0.55 versus 0.35 during the treatment (p < 0.0021). The Lund-Kennedy scale had a pre-treatment average score of 4.21 points versus 1.5 points after the start of Elexacaftor-Tezacaftor-Ivacaftor (p < 0.0001). The average Lund-Mackay and modified Lund-Mackay scores in the pre-treatment time were respectively 14.6 and 16.45 points; and after the start of the therapy, they became 5.87 and 6.73 (p < 0.0001). CONCLUSION: Elexacaftor-Tezacaftor-Ivacaftor was associated with fewer acute exacerbations of chronic rhinosinusitis, and a significant improvement of chronic rhinosinusitis evaluated endoscopically and radiologically. To our knowledge, this is the first study investigating the change in the occurrence of acute exacerbation of chronic rhinosinusitis in patients affected by cystic fibrosis in therapy with Elexacaftor-Tezacaftor-Ivacaftor.

Effects of highly effective modulator therapy on the dynamics of the respiratory mucosal environment and inflammatory response in cystic fibrosis.

BACKGROUND: While the widespread initiation of elexacaftor/tezacaftor/ivacaftor (ETI) has led to dramatic clinical improvements among persons with cystic fibrosis (pwCF), little is known about how ETI affects the respiratory mucosal inflammatory and physiochemical environment, or how these changes relate to lung function. METHODS: We performed a prospective, longitudinal study of adults with CF and chronic rhinosinusitis (CF-CRS) followed at our CF center (n = 18). Endoscopic upper respiratory tract (paranasal sinus) aspirates from multiple visit dates, both pre- and post-ETI initiation, were collected and tested for cytokines, metals, pH, and lactate levels. Generalized estimating equations were used to identify relationships between ETI and upper respiratory tract (URT) biomarker levels, and between URT biomarkers and lung function or clinical sinus parameters. RESULTS: ETI was associated with decreased upper respiratory mucosal cytokines B-cell activating factor (BAFF), IL-12p40, IL-32, IL-8, IL-22 and soluble tumor necrosis factor-1 (sTNFR1), and an increase in a proliferation-inducing ligand (APRIL) and IL-19. ETI was also associated with decreased URT levels of copper, manganese, and zinc. In turn, lower URT levels of BAFF, IL-8, lactate, and potassium were each associated with ~1.5% to 4.3% improved forced expiratory volume in 1 s (FEV1), while higher levels of IFNγ, iron, and selenium were associated with ~2% to 10% higher FEV1. CONCLUSIONS: Our observations suggest a dampening of inflammatory signals and restriction in microbial nutrients in the upper respiratory tract with ETI. These findings improve our understanding of how ETI impacts the mucosal environment in the respiratory tract, and may give insight into the improved infectious and inflammatory status and the resulting clinical improvements seen in pwCF.

Impact of elexacaftor/tezacaftor/ivacaftor on lipid and fat-soluble vitamin levels and association with body mass index.

INTRODUCTION: Cystic fibrosis transmembrane conductance regulator (CFTR) modulators improve gastrointestinal absorption of nutrients and may result in changes in body mass index (BMI), serum lipids, and fat-soluble vitamin levels. We hypothesized that serum lipids and vitamin levels would increase with CFTR modulator therapy and that greater increase in lipids and vitamin levels would be related to greater increase in BMI. METHODS: A retrospective study was performed to evaluate the impact of elexacaftor/tezacaftor/ivacaftor (ETI) on nutritional parameters, serum lipids, and fat-soluble vitamin levels. Pre-ETI values (<2 years prior) and post-ETI values (>1 month after) were compared. Linear regression was used to evaluate whether change in BMI is associated with the change in lipid and/or vitamin levels and whether modulator duration is associated with the degree of rise in lipid and/or vitamin levels. RESULTS: Adults and adolescents with CF (n = 137) were evaluated before and 31-300 days after starting ETI. Median BMI (adults 21.9 vs. 23.5 kg/m2 ; adolescents 48 vs. 63 percentile) increased after initiation of ETI. Total cholesterol (126 vs. 154 mg/dL), low-density lipoprotein cholesterol (63 vs. 78 mg/dL), non-high-density lipoprotein cholesterol (84 vs. 102 mg/dL), and high density lipoprotein cholesterol (43 vs. 49 mg/dL) increased after ETI, while triglycerides and very low density lipoprotein did not change. Median values for vitamin D (34.5 vs. 38.0 ng/mL) and vitamin A (40.1 vs. 47.9 µg/dL) increased, while vitamin E did not change significantly. There was no significant correlation between BMI change or duration of modulator therapy with vitamin levels or lipid changes. CONCLUSION: After initiation of ETI therapy, serum lipids increased in our population, but most values remained within the normal range. Vitamins A and D levels increased post-ETI and no changes were noted in vitamin E. No significant correlation between the degree of BMI change and the magnitude of increase in lipids or vitamin levels was found.

Gilbert's syndrome leads to elevated bilirubin after initiation of elexacaftor/tezacaftor/ivacaftor in people with cystic fibrosis.

Nine people with cystic fibrosis (pwCF) were found to have isolated elevations in serum total bilirubin after starting elexacaftor/tezacaftor/ivacaftor (ETI) that were associated with Gilbert's Syndrome. In longitudinal examination, total bilirubin levels increased substantially after initiation of ETI without elevations in liver transaminases in those with this syndrome. Because elevated bilirubin levels in Gilbert's Syndrome are benign, ETI was able to be continued in these individuals. Genetic testing for this relatively common syndrome should be strongly considered for pwCF experiencing isolated hyperbilirubinemia after starting ETI, since appropriate diagnosis may help pwCF avoid unnecessary interruption in this therapy with significant health benefits in CF.

Elexacaftor/tezacaftor/ivacaftor improves chronic rhinosinusitis detected by magnetic resonance imaging in children with cystic fibrosis on long-term therapy with lumacaftor/ivacaftor.

INTRODUCTION: Previous studies using magnetic resonance imaging (MRI) demonstrated early onset and progression of chronic rhinosinusitis (CRS) from infancy to school age, and response to lumacaftor/ivacaftor (LUM/IVA) therapy in children with cystic fibrosis (CF). However, the effect of elexacaftor/tezacaftor/ivacaftor (ELX/TEZ/IVA) on CRS detected by MRI in children with CF and at least one F508del mutation, and potential incremental effects of ELX/TEZ/IVA compared to LUM/IVA in F508del homozygous children have not been studied. METHODS: 30 children with CF with at least one F508del mutation underwent three longitudinal paranasal sinus MRI before (MRI1), without (n = 16) or with LUM/IVA therapy (n = 14, MRI2), and with ELX/TEZ/IVA therapy (MRI3, mean age at therapy initiation 11.1 ± 3.4y, range 6-16y). MRI were evaluated using the CRS-MRI score. RESULTS: After therapy initiation with ELX/TEZ/IVA, the prevalence and in maxillary and sphenoid sinuses the dominance of mucopyoceles decreased (35% vs. 0 %, p<0.001 and 26% vs. 8 %, p < 0.05, respectively). This leads to a reduction in mucopyocele subscore (-3.4 ± 1.9, p < 0.001), and sinus subscores in MRI3 (maxillary sinus: -5.3 ± 3.1, p < 0.001, frontal sinus: -1.0 ± 1.9, p < 0.01, sphenoid subscore: -2.8 ± 3.5, p < 0.001, ethmoid sinus: -1.7 ± 1.9, p < 0.001). The CRS-MRI sum score decreased after therapy initiation with ELX/TEZ/IVA by -9.6 ± 5.5 score points (p < 0.001). The strength in reduction of mucopyoceles subscore and CRS-MRI sum score was independent of a pretreatment with LUM/IVA from MRI1-MRI2 (p = 0.275-0.999). CONCLUSIONS: ELX/TEZ/IVA therapy leads to improvement of CRS in eligible children with CF. Our data support the role of MRI for comprehensive monitoring of CRS disease severity and response to therapy in children with CF.

Eradication of Mycobacterium abscessus infection in cystic fibrosis with initiation of Elexacaftor/Tezacaftor/Ivacaftor.

Mycobacterium abscessus is a nontuberculous mycobacterium that is often multi-drug resistant, difficult to eradicate and associated with a rapid decline in lung function in cystic fibrosis (CF). Elexacaftor/Tezacaftor/Ivacaftor (ETI) is a combination CFTR modulator that improves lung function and decreases exacerbations, but limited data exists about its impact on respiratory infections. A 23-year-old male with CF (F508del, unknown) was diagnosed with Mycobacterium abscessus subspecies abscessus infection. He completed 12-weeks of intensive therapy, followed by oral continuation therapy. Antimicrobials were later discontinued for optic neuritis secondary to linezolid. He remained off antimicrobials with persistently positive sputum cultures. He then initiated ETI, and bronchoscopy eight months later suggested eradication of M. abscessus. By modulating CFTR protein function, ETI may improve innate airway defence mechanisms, facilitating the clearance of infections such as M. abscessus. This case highlights the potential positive implications of ETI on the challenging treatment of M. abscessus infections in CF.

Analysis of iron status after initiation of elexacaftor/tezacaftor/ivacaftor in people with cystic fibrosis.

BACKGROUND: Iron deficiency is highly prevalent in people with cystic fibrosis (PwCF). While elexacaftor/tezacaftor/ivacaftor (ETI) has shown remarkable improvements in respiratory symptoms in PwCF, the effect of ETI on iron status remains unknown. This study aims to identify the effect of ETI on iron status in PwCF. METHODS: A single-center retrospective cohort study of 127 adult PwCF was conducted to assess the impact of ETI on iron, ferritin, transferrin levels, and percent saturation of transferrin (PSAT). Data were collected from the electronic medical record from January 2017 to September 2022, encompassing 2 years before and after ETI initiation. The primary outcome was serum iron parameters: iron, ferritin, transferrin, and PSAT levels following ETI treatment. Secondary outcomes analyzed iron supplementation. Univariate and multivariate mixed-effects models were used for the analysis of ETI. RESULTS: After adjusting for covariates, following ETI initiation, the mean iron level increased by 20.24 µg/dL (p < .001), ferritin levels were 31.4% (p < .001) higher, PSAT showed a 5.09 percentage point increase (p < .001), and transferrin levels increased by 2.71 mg/dL (p = .439). Patients with and without iron supplementation experienced a significant increase in iron after ETI (p < .001). CONCLUSIONS: ETI is associated with a significant increase in iron, ferritin, and PSAT levels. Patients with and without iron supplementation demonstrated a significant increase in iron. This study shows the benefits of ETI on iron status in PwCF. However, further translational studies are required to understand the impact of ETI on iron absorption and metabolism in PwCF.