Who are the 10%? - Non eligibility of cystic fibrosis (CF) patients for highly effective modulator therapies

Beyond the 10%: Unraveling the genetic diversity in Turkish cystic fibrosis patients not eligible for CFTR modulators

BACKGROUND

Cystic fibrosis (CF) is an autosomal recessive disease caused by variants of CFTR gene. Over 2000 variants have been identified, and new drugs called CFTR modulators have been developed to target specific defects in the CFTR protein. However, these drugs are only suitable for patients with certain variants of CFTR, and eligibility rates vary depending on race and geographical region. This study aimed to reveal the detailed genotype and clinical characteristics of people with CF (pwCF) at our center in Turkey, a developing country, who are not eligible for CFTR modulators.

METHODS

A total of 445 pwCF followed up at Marmara University were reviewed retrospectively. Variants of the patients ineligible to CFTR modulators were classified based on American College of Medical Genetics guidelines, CFTR classification, the change in the encoded protein, and the variant type.

RESULTS

The study revealed that 139 (31.2%) patients weren't eligible for CFTR modulators. There were 60 different variants in the 276 alleles, as two were missing. The majority of patients had missense or nonsense variants, and that the most common variant was c.1545_1546del, which can be said unique to this geography.

CONCLUSION

The study highlights the importance of detecting the variants of ineligible patients in detail to guide future approaches for more targeted and effective interventions in CF care. Testing the effectiveness of CFTR modulators for rare or newly occurring variants is crucial to ensure equal access for pwCF to these therapies from different racial backgrounds and ethnic minorities.

Impact of sociodemographic status and sex on chronic rhinosinusitis and olfaction in people with cystic fibrosis

BACKGROUND

Sociodemographic status (SDS) including race/ethnicity and socioeconomic status as approximated by education, income, and insurance status impact pulmonary disease in people with cystic fibrosis (PwCF). The relationship between SDS and chronic rhinosinusitis (CRS) remains understudied.

METHODS

In a prospective, multi-institutional study, adult PwCF completed the 22-Question SinoNasal Outcome Test (SNOT-22), Smell Identification Test (SIT), Questionnaire of Olfactory Disorder Negative Statements (QOD-NS), and Cystic Fibrosis Questionnaire-Revised (CFQ-R). Lund-Kennedy scores, sinus computed tomography, and clinical data were collected. Data were analyzed across race/ethnicity, sex, and socioeconomic factors using multivariate regression.

RESULTS

Seventy-three PwCF participated with a mean age of 34.7 ± 10.9 years and 49 (67.1%) were female. Linear regression identified that elexacaftor/tezacaftor/ivacaftor (ETI) use (β = ‒4.09, 95% confidence interval [CI] [‒6.08, ‒2.11], p < 0.001), female sex (β = ‒2.14, 95% CI [‒4.11, ‒0.17], p = 0.034), and increasing age (β = ‒0.14, 95% CI [‒0.22, ‒0.05], p = 0.003) were associated with lower/better endoscopy scores. Private health insurance (β = 17.76, 95% CI [5.20, 30.32], p = 0.006) and >16 educational years (β = 13.50, 95% CI [2.21, 24.80], p = 0.020) were associated with higher baseline percent predicted forced expiratory volume in one second (ppFEV1). Medicaid/Medicare insurance was associated with worse endoscopy scores, CFQ-R respiratory scores, and ppFEV1 (all p < 0.017), and Hispanic/Latino ethnicity was associated with worse SNOT-22 scores (p = 0.047), prior to adjustment for other cofactors. No other SDS factors were associated with SNOT-22, QOD-NS, or SIT scores.

CONCLUSIONS

Differences in objective measures of CRS severity exist among PwCF related to sex, age, and ETI use. Variant status and race did not influence patient-reported CRS severity measures or olfaction in this study. Understanding how these factors impact response to treatment may improve care disparities among PwCF.

CLINICAL TRIALS

NCT04469439.

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.

Comparison of clinical features of cystic fibrosis patients eligible but not on CFTR modulators to ineligible for CFTR modulators

INTRODUCTION

Cystic fibrosis transmembrane conductance regulator (CFTR) modulator drugs target the underlying defect and improve CFTR function. They are a part of standard care in many countries, but not all patients are eligible for these drugs due to age and genotype. Here, we aimed to determine the characteristics of non-eligible patients for CFTR modulators in the CF registry of Turkey (CFRT) to highlight their clinical needs.

METHODS

This retrospective cohort study included CF patient data from the CFRT in 2021. The decision of eligibility for the CFTR modulator was determined according to the 'Vertex treatment-Finder' on the Vertex® website. Demographic and clinical characteristics of patients were compared between eligible (group 1) and ineligible (group 2) groups for CFTR modulators.

RESULTS

Among the study population (N = 1527), 873 (57.2%) were in group 1 and 654 (42.8%) were in group 2. There was no statistical difference between groups regarding sex, meconium ileus history, diagnoses via newborn screening, FEV1 z-score, CF-associated complications, organ transplant history, and death. Patients in group 2 had a higher incidence of pancreatic insufficiency (87.7% vs. 83.2%, p = .010), lower median height z-scores (-0.87 vs. -0.55, p < .001), lower median body mass index z-scores (-0.65 vs. -0.50, p < .001), longer days receiving antibiotics due to pulmonary exacerbation (0 [interquartile range, IQR: 0-2] vs. 0 [IQR: 0-7], p = 0.001), and more non-invasive ventilation support (2.6% vs. 0.9%, p = 0.008) than patients in group 1.

CONCLUSION

The ineligible group had worse clinical outcomes than the eligible group. This highlights their need for life-changing drugs to improve clinical outcomes.

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").

How representative are clinical trial cohorts of the general CF population? Implications for trial planning

Understanding the number of patients eligible to participate in research is important to design protocols and define research priorities. We reviewed the records of all patients with CF, age 12+, who receive care at our centre. We assessed their eligibility for trial participation based on common trial inclusion/exclusion criteria. 643 patients were included in the analysis, 31 were modulator ineligible(MI). Only 198(31 %) of the total cohort and 7(23 %) of the MI cohort were eligible for participation based on the hypothetical criteria. The most common reason for ineligibility was ppFEV1 ≥90 % followed by clinical instability, complex comorbidity and anticipated inability to adhere to the protocol. We suggest this would be a useful exercise for centres planning to either participate in, or refer subjects into, upcoming trials to undertake for their own cohort. We also make suggestions for protocol designs that optimise the number of patients who are eligible to participate.

A systematic review on the use of bacteriophage in treating Staphylococcus aureus and Pseudomonas aeruginosa infections in cystic fibrosis

BACKGROUND

Respiratory infections caused by Staphylococcus aureus and Pseudomonas aeruginosa are a major concern for cystic fibrosis (CF) patients due to increasing antibiotic resistance. Bacteriophages, which are viruses that selectively target and kill bacteria, are being studied as an alternative treatment for these infections. This systematic review evaluates the safety and effectiveness of bacteriophages for the treatment of CF-related infections caused by S. aureus and/or P. aeruginosa. We conducted a search for original, published articles in the English language up to March 2023. Studies that administered bacteriophages via intravenous, nebulised, inhaled, or intranasal routes were included, with no comparators required. In vitro and in vivo studies were eligible for inclusion, and only animal in vivo studies that utilised a CF transmembrane conductance regulator (CFTR) animal model were included. Bacteriophage treatment resulted in a decrease in bacterial load in both humans and animals infected with P. aeruginosa. Complete eradication of P. aeruginosa was only observed in one human subject. Additionally, there was a reduction in biofilm, improvement in resistance profile, and reduced pulmonary exacerbations in individual case reports. Evidence suggests that bacteriophage therapy may be a promising treatment option for CF-related infections caused by P. aeruginosa and S. aureus. However, larger and more robust trials are needed to establish its safety and efficacy and create necessary evidence for global legislative frameworks.

Cystic fibrosis year in review 2022

Remarkable medical advancements have been made for people with cystic fibrosis (CF) in recent years, with an abundance of research continuing to be conducted worldwide. With concern for limitations in access to highly effective CFTR modulators, as well as the recent Coronavirus Disease-19 pandemic, there has been a consistent effort to understand and improve CF screening, disease burden, diagnosis, and management. Our aim in this review is to present articles from 2022 with an emphasis on clinically relevant studies. We hope this will serve as a broad overview of the research published in the past year.

The Lived Experience of African American Persons with Cystic Fibrosis

Background: Cystic fibrosis (CF) is a rare genetic disease affecting approximately 30,000 people in the United States (US). African American persons with CF are even rarer, comprising approximately 5% of this population. Purpose: The purpose of this study was to explore the lived experiences of African American persons with CF to identify potential disparities in health care. Methods: Descriptive phenomenology was used to explore lived experiences of African American persons with CF over age 18 recruited from CF Foundation-accredited Centers in the US, CF-specific social media, and via snowball sampling. Study data was obtained through telephone interviews that were audio-recorded, transcribed verbatim, and analyzed using Colaizzi's method of thematic analysis. Results: Six men and six women (ages 23-45) completed the study. Interviews revealed three themes: (1) Accepting a Diagnosis of CF; (2) Desiring a Normal Life while Living with an Invisible Disease; and 3) A Slippery Slope of Subtle Racism. Each theme had 2-3 subthemes. Conclusions: It is critical to explore the unique challenges faced by African American persons with CF in order to develop interventions that improve their daily lives and create better futures. Implications for Practice: Findings highlight the unique challenges faced by underrepresented groups with CF and the need to address health inequities to improve care delivery.

Advancing the pipeline of cystic fibrosis clinical trials: a new roadmap with a global trial network perspective

The growing use of modulator therapies aimed at restoring cystic fibrosis transmembrane conductance regulator (CFTR) protein function in people with cystic fibrosis has fundamentally altered clinical trial strategies needed to advance new therapeutics across an orphan disease population that is now divided by CFTR modulator eligibility. The development of a robust pipeline of nucleic acid-based therapies (NABTs)-initially directed towards the estimated 10% of the cystic fibrosis population who are genetically ineligible for, or intolerant of, CFTR modulators-is dependent on the optimisation of restricted trial participant resources across multiple development programmes, a challenge that will preclude the use of gold standard placebo-controlled trials. Advancement of a full pipeline of symptomatic therapies across the entire cystic fibrosis population will be challenged by smaller effect sizes and uncertainty regarding their clinical importance in a growing modulator-treated population with more mild and stable pulmonary disease. In this Series paper, we aim to lay the foundation for clinical trial strategy and community partnership that must deviate from established and familiar precedent to advance the future pipeline of cystic fibrosis therapeutics.

Understanding and addressing the needs of people with cystic fibrosis in the era of CFTR modulator therapy

Cystic fibrosis is a multiorgan disease caused by impaired function of the cystic fibrosis transmembrane conductance regulator (CFTR). Since the introduction of the CFTR modulator combination elexacaftor-tezacaftor-ivacaftor (ETI), which acts directly on mutant CFTR to enhance its activity, most people with cystic fibrosis (pwCF) have seen pronounced reductions in symptoms, and studies project marked increases in life expectancy for pwCF who are eligible for ETI. However, modulator therapy has not cured cystic fibrosis and the success of CFTR modulators has resulted in immediate questions about the new state of cystic fibrosis disease and clinical challenges in the care of pwCF. In this Series paper, we summarise key questions about cystic fibrosis disease in the era of modulator therapy, highlighting state-of-the-art research and clinical practices, knowledge gaps, new challenges faced by pwCF and the potential for future health-care challenges, and the pressing need for additional therapies to treat the underlying genetic or molecular causes of cystic fibrosis.

CFTR modulator therapy: transforming the landscape of clinical care in cystic fibrosis

Following discovery of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in 1989 and subsequent elucidation of the varied CFTR protein abnormalities that result, a new era of cystic fibrosis management has emerged-one in which scientific principles translated from the bench to the bedside have enabled us to potentially treat the basic defect in the majority of children and adults with cystic fibrosis, with a resultant burgeoning adult cystic fibrosis population. However, the long-term effects of these therapies on the multiple manifestations of cystic fibrosis are still under investigation. Understanding the effects of modulators in populations excluded from clinical trials is also crucial. Furthermore, establishing appropriate disease measures to assess efficacy in the youngest potential trial participants and in those whose post-modulator lung function is in the typical range for people without chronic lung disease is essential for continued drug development. Finally, recognising that a health outcome gap has been created for some people and widened for others who are not eligible for, cannot tolerate, or do not have access to modulators is important.

Reproductive Counseling and Care in Cystic Fibrosis: A Multidisciplinary Approach for a New Therapeutic Era

With the advent of highly effective modulator therapies, many people with cystic fibrosis (CF) are living longer, healthier lives. Pregnancy rates for women with CF more than doubled between 2019 and 2021, reflecting increases in both planned and unplanned pregnancies. For men with CF, CF-associated infertility can be mitigated with assistive reproductive technology, yet patient knowledge of these challenges and options is variable. Preconception and prenatal counseling for individuals with CF and for parents of children with CF who wish to expand their families requires nuanced discussions to promote informed reproductive decisions, drawing from a combination of standard practice recommendations and CF-specific assessments. This review article synthesizes the current literature and practice recommendations regarding reproductive counseling and care in CF, outlining the role of genetic counseling, carrier screening, teratogen counseling, in vitro fertilization and pre-implantation genetic diagnosis, and careful assessment and management of cystic fibrosis-related diabetes when present. Via a multidisciplinary, patient-centered approach, clinicians can support adults with CF and parents of children with CF as they make informed reproductive decisions and embark on family planning.

Critical disease burdens of Australian adults with cystic fibrosis: Results from an online survey

BACKGROUND

The objective of this study was to conduct a web-based questionnaire to investigate self-reported phenotypes and disease burdens of individuals living in Australia and diagnosed with cystic fibrosis (CF) using a case-control study design.

METHODS

An online questionnaire was distributed to individuals with CF and healthy control subjects. Overall health rating, medications, family history, education, clinical indicators of disease, and symptoms, including their severity and frequency, were evaluated.

RESULTS

There was a total of 119 respondents consisting of 59 people living with CF and 60 controls. The CF cohort had significantly lower tertiary educational levels compared to controls. The analysis specific to the CF cohort depicted a significant correlation between the frequency of hospitalizations and the level of education in the CF cohort. Of the 26 self-reported symptoms of CF that were analyzed, 14 were significantly higher in the people living with CF. The CF cohort reporting symptoms of chronic pain (25%) described an increase in the burden of disease, depicting a 30% longer mean hospitalization, increased consumption of medications and significant relationships with four other symptoms, including muscle aches, digestive issues, pancreatic insufficiency, and abdominal swelling.

CONCLUSIONS

The nationwide survey identified a diverse range of clinical manifestations experienced by the Australian CF population. Chronic pain, linked to aging and the changing landscape of disease, was a significant indicator of the burden of disease. A comprehensive understanding of the phenotypic profiles and symptom variability will contribute to future research and provide insights into the impacts of disease and the burden of therapy, particularly in children, at the start of their health journey.

Furin as a therapeutic target in cystic fibrosis airways disease

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

Characterization of CFTR mutations in people with cystic fibrosis and severe liver disease who are not eligible for CFTR modulators

Cystic-fibrosis-related liver disease (CFLD) is a variable phenotype of CF. The severe CFLD variant with cirrhosis or portal hypertension has a poor prognosis and life expectancy. CFTR modulator therapies are now available for people with CF and eligibility for such treatment is based on their CFTR genotype. We evaluated the genetic eligibility for elexacaftor, tezacaftor, ivacaftor (ETI), and ivacaftor (IVA) monotherapy in a previously reported CF cohort of 1591 people with CF of whom 171 with severe CFLD. Based on their CFTR mutations, 13% (N=184/1420) of subjects without CFLD and 11% (N=19/171) of those with severe CFLD are not eligible for either ETI or IVA therapy. The non-eligible patients without CFLD or with severe CFLD can currently not take advantage of the potential benefits of these new treatments. Although this study cannot provide any data regarding the effect of ETI or IVA on the progression of severe CFLD, the consequences for ineligibility of patients with extreme liver phenotype may be even more significant because of their poorer disease risk profile.

Managing cystic fibrosis in children aged 6-11yrs: a critical review of elexacaftor/tezacaftor/ivacaftor combination therapy

INTRODUCTION

Cystic fibrosis is a life-limiting, autosomal recessive genetic disorder resulting in multi-organ disease due to CF transmembrane conductance regulator (CFTR) protein dysfunction. CF treatment previously focused on mitigation of disease signs and symptoms. The recent introduction of highly effective CFTR modulators, for which ~90% of people with CF are CFTR variant-eligible, has resulted in substantial health improvements.

AREAS COVERED

In this review, we will describe the clinical trials leading to approval of the highly effective CFTR modulator, elexacaftor-tezacaftor-ivacaftor (ETI), with a focus on the safety and efficacy of this treatment in children aged 6-11 years.

EXPERT OPINION

The use of ETI in variant-eligible children aged 6-11 is associated with marked clinical improvements with a favorable safety profile. We anticipate that introduction of ETI in early childhood may result in the prevention of pulmonary, gastrointestinal, and endocrine complications from CF, consequently leading to previously unimaginable gains in the quality and quantity of life. However, there is an urgent need to develop effective treatments for the remaining 10% of people with CF who are not eligible or unable to tolerate ETI treatment, and to increase access of ETI to more pwCF across the world.