Prenatal cystic fibrosis transmembrane conductance regulator modulator therapy: A promising way to change the impact of cystic fibrosis

[Cystic fibrosis in childhood and adulthood]

BACKGROUND

Cystic fibrosis (CF, or mucoviscidosis) is one of the rare diseases with a fatal course and with the highest prevalence. Formerly known as a purely childhood disease, this multisystemic disease follows an autosomal recessive inheritance pattern and results in a malfunction of the cystic fibrosis transmembrane conductance regulator (CFTR) channel, leading to the production of viscous secretions. The prognosis and outcome of CF are determined by the severity of the involvement of the lungs. Other typically affected organs include the pancreas, liver and intestines.

OBJECTIVE

This article reviews the clinical presentation and evolution of CF with a focus on the new era of the highly effective CFTR modulator treatment.

MATERIAL AND METHODS

An overview of the current state of knowledge on the care for CF patients is presented.

RESULTS AND DISCUSSION

The introduction of the CF newborn screening, the increased understanding of the disease and the development of novel treatment options have substantially increased the quality of life and life expectancy of people with CF. As a result, more than half of CF patients in Germany are now older than 18 years of age and the complications of a chronic disease as well as organ damage due to the intensive treatment are gaining in importance. The highly effective CFTR modulator treatment results in a significant improvement in CFTR function, lung function, body mass index and quality of life and is available to approximately 90% of patients in Germany, based on the genotype. Nevertheless, further research including the development of causal treatment, e.g., gene therapy, targeting the underlying defect in the remaining 10% of CF patients, is urgently needed. Even in adult patients, CF with a mild course or a CFTR-related disease should be considered, e.g., in cases of bronchiectasis and/or recurrent abdominal complaints.

Extent of foetal exposure to maternal elexacaftor/tezacaftor/ivacaftor during pregnancy

BACKGROUND AND PURPOSE

Cystic fibrosis (CF) patients are living longer and healthier due to improved treatments, e.g. cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy elexacaftor/tezacaftor/ivacaftor (ETI), with treatment possibly occurring in pregnancy. The risk of ETI to foetuses remain unknown. Thus the effect of maternally administered ETI on foetal genetic and structural development was investigated.

EXPERIMENTAL APPROACH

Pregnant Sprague Dawley rats were orally treated with ETI (6.7 mg·kg-1·day-1 elexacaftor + 3.5 mg·kg-1·day-1 tezacaftor + 25 mg·kg-1·day-1 ivacaftor) for 7 days from E12 to E19. Tissue samples collected at E19 were analysed using histology and RNA sequencing. Histological changes and differentially expressed genes (DEG) were assessed.

KEY RESULTS

No overt structural abnormalities were found in foetal pancreas, liver, lung and small intestine after 7-day ETI exposure. Very few non-functionally associated DEG in foetal liver, lung and small intestine were identified using RNA-seq. 29 DEG were identified in thymus (27 up-regulated and two down-regulated) and most were functionally linked to each other. Gene ontology enrichment analysis revealed that multiple muscle-related terms were significantly enriched. Many more DEG were identified in cortex (44 up-regulated and four down-regulated) and a group of these were involved in central nervous system and brain development.

CONCLUSION AND IMPLICATION

Sub-chronic ETI treatment in late pregnancy does not appear to pose a significant risk to the genetic and structural development of many foetal tissues. However, significant gene changes in foetal thymic myoid cells and cortical neuronal development requires future follow-up studies to assess the risk to these organs.

[Therapeutics in cystic fibrosis: Clinical revolution and new challenges]

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

Fetal drug exposure after maternally administered CFTR modulators Elexacaftor/Tezacaftor/Ivacaftor in a rat model

BACKGROUND

The potential effects of the very effective cystic fibrosis triple combination drug, Elexacaftor/Tezacaftor/Ivacaftor (ETI) in pregnancy on prenatal development of offspring remain largely unknown.

RESEARCH QUESTION

We aimed to investigate the fetal tissue distribution pattern of maternally administered ETI by placental transfer in the rat fetuses.

STUDY DESIGN AND METHODS

Sprague Dawley pregnant rats were administered ETI (6.7 mg/kg/d elexacaftor + 3.5 mg/kg/d tezacaftor + 25 mg/kg/d ivacaftor) traced with [3 H]-ivacaftor in single dose acute experiments (intraperitoneal injection) or treated orally with ETI (the same dose) for 7 days in sub-chronic experiments. Fetal tissue samples were collected at embryonic day (E) 19 and analyzed using liquid scintillation counting for acute experiments or liquid chromatography-mass spectrometry for sub-chronic experiments.

RESULTS

On day E19, after acute exposure, the entry of ivacaftor into fetal brain (brain/plasma concentration ratios <50%) was significantly lower than to other tissues (>100%). However, after sub-chronic exposure, the entry of all 3 components into the developing brain was comparably extensive as into other tissues (tissue/plasma ratios, 260 - 1000%). Each component of ETI accumulated in different fetal tissues to approximately equal extent. Inter-litter differences on fetal drug distribution were found in cortex for ivacaftor, muscle for tezacaftor and cortex and mid/hindbrain for elexacaftor. Fetal plasma concentrations of ETI (ng/mL) were variable between litters. The entry of ivacaftor and tezacaftor into adult brain appeared to be restricted (<100%).

INTERPRETATION

Fetal rats are exposed to maternally ingested ETI after sub-chronic exposure, potentially impacting fetal development. The brain entry data highlights the need for attention be paid to any long-term potential effects ETI exposure could have on normal brain development.

Use of CFTR modulators in special populations, part 1: Pregnancy and lactation

Safety and efficacy data regarding cystic fibrosis transmembrane conductance regulator (CFTR) modulator use in the setting of pregnancy or breastfeeding remains lacking due to exclusion from key trials and lack of multicenter prospective and retrospective studies in the post-CFTR modulator era. A scoping review of English articles from the period of January 1, 2012, to July 31, 2023, was conducted utilizing PubMed and EmBase databases with the following terms: "special population (pregnancy, lactation, breastfeeding)" AND "ivacaftor OR lumacaftor OR tezacaftor OR elexacaftor"; "cystic fibrosis transmembrane conductance regulator" AND "off label drug use." Search results were reviewed by title and abstract for duplications and relevance. Relative to pregnancy or breastfeeding, a total of 18 publications were included for review. Majority of case reports and surveys concluded maternal and infant health were preserved throughout gestation. Likewise, breastfeeding infant case reports show possible changes in liver function and lens opacities, though risk may be increased with both in-utero and breastfeeding exposure. Ivacaftor (IVA) and lumacaftor (LUM) concentrations in fetal cord blood and maternal blood were found to be equivalent. Yet, low concentrations of IVA and LUM were detectable in breastmilk and infant plasma. Current safety data surrounding CFTR modulator use in the setting of pregnancy and lactation is relatively reassuring; however, long-term safety remains unclear, necessitating ongoing observation, and reporting by care teams. As such, treatment decisions should be individualized and coproduced.

The modern landscape of fertility, pregnancy, and parenthood in people with cystic fibrosis

PURPOSE OF REVIEW

With improved long-term survival and the expanding availability of cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapies that treat the underlying genetic defect in cystic fibrosis, more people are interested in parenthood. Cystic fibrosis care centers and people with cystic fibrosis need more information to guide decisions related to parenting.

RECENT FINDINGS

Here we present currently available data on fertility, pregnancy, and parenthood in the modern era of cystic fibrosis care. Fertility may be improving in female individuals with cystic fibrosis with the use of CFTR modulator therapies, and there is an associated increase in annual pregnancies. Infertility in male individuals with cystic fibrosis remains approximately 97-98% and is unchanged with CFTR modulators in those already born with cystic fibrosis. As more female individuals with cystic fibrosis experience pregnancy, questions remain about the impact of pregnancy on their health and that of their child. Fortunately, there are multiple routes to becoming a parent; however, more work is needed to understand the impact of pregnancy and parenthood in the context of CF as some previous data suggests potential challenges to the health of parents with cystic fibrosis.

SUMMARY

We encourage cystic fibrosis care teams to have knowledge and resources available to support the reproductive goals of all individuals with cystic fibrosis.

Update on Cystic Fibrosis in Pediatric Patients

PURPOSE OF REVIEW

Cystic fibrosis is an inherited, multisystem disease that affects the gastrointestinal system in numerous ways. This article reviews the nutritional, gastrointestinal, and hepatobiliary manifestations of cystic fibrosis with an emphasis on the effects of CFTR modulator therapy.

RECENT FINDINGS

The life expectancy of individuals with cystic fibrosis has increased substantially in recent years. CFTR modulator therapy improves pulmonary function and results in weight gain. An individualized approach to nutrition is encouraged. Pancreatic exocrine function may improve with intervention early in life. The use of non-invasive methods to screen for hepatobiliary involvement is recommended. Highly effective CFTR modulators lead to increased survival and improved quality of life for many individuals. Their effects on gastrointestinal symptoms and hepatobiliary disease are not fully understood. Patient-reported outcome measures and biomarkers are important clinical endpoints for studying the effects of modulators.

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.

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.

Ocular development after highly effective modulator treatment early in life

Highly effective cystic fibrosis (CF) transmembrane conductance regulator (CFTR) modulator therapies (HEMT), including elexacaftor-tezacaftor-ivacaftor, correct the underlying molecular defect causing CF. HEMT decreases general symptom burden by improving clinical metrics and quality of life for most people with CF (PwCF) with eligible CFTR variants. This has resulted in more pregnancies in women living with CF. All HEMT are known to be able pass through the placenta and into breast milk in mothers who continue on this therapy while pregnant and breast feeding. Toxicity studies of HEMT in young rats demonstrated infant cataracts, and case reports have reported the presence of congenital cataracts in early life exposure to HEMT. This article reviews the evidence for how HEMT influences the dynamic and interdependent processes of healthy and abnormal lens development in the context of HEMT exposure during pregnancy and breastfeeding, and raises questions that remain unanswered.