Incidence of transaminitis in adults with cystic fibrosis taking elexacaftor/tezacaftor/ivacaftor

Liver biochemical indexes and cholesterol metabolism in cystic fibrosis patients with F508del/CFTR variant genotype after elexacaftor/tezacaftor/ivacaftor treatment

Modulators of cystic fibrosis transmembrane conductance regulator (CFTR) improved cystic fibrosis (CF) patients' outcome. The elexacaftor/tezacaftor/ivacaftor (ETI) combination was safe and effective improving lung function in patients with different CFTR genotypes, including at least one F508del mutation. However, cases with liver damage were reported. We describe 105 CF patients heterozygous for F508del in trans with another CFTR mutation, treated for 1 year with ETI. We analyzed liver biochemical parameters and cholesterol metabolism, including lathosterol and phytosterols, surrogate markers of cholesterol de-novo synthesis and absorption, respectively. The treatment significantly improved sweat chloride, body mass index and forced expiratory volume in 1 s, whereas it caused a significant increase of total and conjugated bilirubin, ALT and GGT, even if no patients developed CF liver disease. Such alterations were less relevant than those previously observed in ETI-treated F508del homozygous patients. Furthermore, ETI treatment significantly increased serum cholesterol by enhancing its absorption (correlation between serum cholesterol and phytosterols). Whereas, we observed a normalization of de-novo biosynthesis (lathosterol reduction) that was not observed in homozygous patients. These data suggest that the second mutation in trans with the F508del contributes to reduce the liver cholesterol accumulation and thus, the triggering of liver inflammation. However, no differences in the alteration of biochemical indexes were observed between CF patients with and without liver steatosis, and between patients with different mutations in trans with the F508del. Such data suggest to further investigate the effects of ETI therapy on liver function indexes and new predictive biomarkers.

Cystic fibrosis year in review 2023

This past year, there were many important advances for patients with cystic fibrosis (CF). Of the many publications related to CF in 2023, there was further evaluation of highly effective modulator therapy, new assessments and guidelines for clinical manifestations and therapies for CF, advances in newborn screening and diagnosis, and evaluation of outcomes for people with CF transmembrane conductance regulator-related metabolic syndrome/CF screen positive, inconclusive diagnosis. The aim of this review article is not to provide a full assessment of the wide range of articles published in 2023, but to provide a brief review of publication that may lead to changes in clinical care.

One year of treatment with elexacaftor/tezacaftor/ivacaftor in patients with cystic fibrosis homozygous for the F508del mutation causes a significant increase in liver biochemical indexes

Introduction: Modulators of cystic fibrosis transmembrane conductance regulator mutated protein significantly improved the outcome of patients with cystic fibrosis (CF). We describe 63 patients who were independently followed up in two CF regional centers (i.e., Campania and Tuscany regions). Methods: All patients were homozygous for the F508del mutation and were treated with lumacaftor/ivacaftor (LI) for 3 years, followed by 1 year of treatment with elexacaftor/tezacaftor/ivacaftor (ETI). We studied the biochemical parameters of liver damage and cholesterol metabolism. Results: Beyond the improvement of BMI and lung function with LI treatment and even more with ETI, we found that the 3 years of LI treatment significantly improved liver function parameters (total and conjugated bilirubin, ALT, AP, and GGT), while the subsequent ETI treatment caused a significant increase of such parameters. Discussion: We confirm that treatment with LI does not correct hypocholesterolemia, whereas treatment with ETI significantly increases serum cholesterol. Such an increase is likely due to enhanced de novo biosynthesis, as indicated by the significant increase in serum lathosterol, and it is likely that the subsequent liver cholesterol accumulation may contribute to triggering inflammation and worsening liver biochemical indexes. The increase in serum bilirubin and ALT that we observed in approximately 94% and 84% of patients treated with ETI, respectively, suggests further investigation of the impact of ETI therapy on liver function indexes.

Aetiology of Significant Liver Test Abnormalities in a Single-Centre Cohort of People with Cystic Fibrosis Exposed to Elexacaftor/Tezacaftor/Ivacaftor, Utilizing the Updated RUCAM

BACKGROUND

The cystic fibrosis (CF) transmembrane conductance regulator (CFTR) modulator elexacaftor/tezacaftor/ivacaftor (E/T/I) has been associated with substantial multisystem benefits for people with CF eligible for therapy. In a minority, tolerance has been limited by hepatic toxicity. It is unknown whether there may be particular risk factors for significant drug-induced elevation in transaminases.

OBJECTIVE

We aimed to determine the cause of raised transaminases following the introduction of E/T/I, and whether E/T/I can safely be continued in some individuals with elevated transaminases.

METHODS

At a large, single, adult CF centre, individuals with transaminases >3 × the upper limit of normal (ULN) since commencing E/T/I underwent clinical assessment to exclude known causes of raised transaminases. Where an alternative cause could not be identified, individuals were discussed with hepatology to advise on further investigations to establish aetiology in addition to calculation of the updated Roussel Uclaf Causality Assessment Method (RUCAM) score to assess causality grading of drug-induced liver injury (DILI) due to E/T/I, and to guide management of ongoing CFTR modulator therapy.

RESULTS

Of 337 adults taking E/T/I for a median of 27 months, 19 (5.6%) had transaminases >3 × ULN. In 12 individuals, there was clear evidence of an aetiology unrelated to E/T/I (RUCAM scores -2 to 1 [excluded-unlikely]). Of the remaining cases, two had RUCAM scores in the 'possible' range and one had a RUCAM score in the 'probable' range. Liver biopsy was performed in four individuals, showing hepatic steatosis in one individual, normal histology in one individual, and hepatocyte necrosis suggestive of DILI in two individuals. E/T/I was suspended in those with hepatocyte necrosis, with one permanent discontinuation due to synthetic dysfunction. One individual with hepatocyte necrosis on histology was successfully re-established on E/T/I therapy.

CONCLUSIONS

Alternative causes were identified in the majority of patients with clinically significant increases in transaminases following E/T/I, highlighting the importance of thorough investigation. Multidisciplinary assessment involving an experienced hepatologist is crucial in cases of diagnostic uncertainty or suggestion of significant DILI, as discontinuation of therapy can have significant consequences for individuals.

Elexacaftor-Tezacaftor-Ivacaftor: A Life-Changing Triple Combination of CFTR Modulator Drugs for Cystic Fibrosis

Cystic fibrosis (CF) is a potentially fatal monogenic disease that causes a progressive multisystemic pathology. Over the last decade, the introduction of CF transmembrane conductance regulator (CFTR) modulator drugs into clinical practice has profoundly modified the lives of many people with CF (PwCF) by targeting the fundamental cause of the disease. These drugs consist of the potentiator ivacaftor (VX-770) and the correctors lumacaftor (VX-809), tezacaftor (VX-661), and elexacaftor (VX-445). In particular, the triple combination of CFTR modulators composed of elexacaftor, tezacaftor, and ivacaftor (ETI) represents a life-changing therapy for the majority of PwCF worldwide. A growing number of clinical studies have demonstrated the safety and efficacy of ETI therapy in both short- and long-term (up to two years of follow-up to date) and its ability to significantly reduce pulmonary and gastrointestinal manifestations, sweat chloride concentration, exocrine pancreatic dysfunction, and infertility/subfertility, among other disease signs and symptoms. Nevertheless, ETI therapy-related adverse effects have also been reported, and close monitoring by a multidisciplinary healthcare team remains vital. This review aims to address and discuss the major therapeutic benefits and adverse effects reported by the clinical use of ETI therapy for PwCF.