Phase 1 Study to Assess the Safety and Pharmacokinetics of Elexacaftor/Tezacaftor/Ivacaftor in Subjects Without Cystic Fibrosis With Moderate Hepatic Impairment

Cystic fibrosis liver disease in the new era of cystic fibrosis transmembrane conductance regulator (CFTR) modulators

Cystic fibrosis liver disease (CFLD) is characterised by a wide heterogenity of manifestations and severity. It represents a major cause of morbidity in people with cystic fibrosis (PwCF), which will be of increasing relevance as survival increases in the new era of cystic fibrosis care. No medical therapy currently available has evidence to treat or prevent progression of liver disease. Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) modulators may be transformative on pulmonary, nutritional and quality of life, but direct effect on long term liver disease outcomes is not yet established. Drug-associated hepatic adverse effects may be common, and clinician familiarity with drug-monitoring recommendations is essential. Longitudinal studies are required to understand the effect of CFTR modulators on the incidence and natural history of CFLD, including with early treatment initiation, in established advanced liver disease, and post liver transplantation.

Management of liver disease and portal hypertension in cystic fibrosis: a review

INTRODUCTION

Cystic fibrosis (CF)-associated liver disease can significantly affect the quality of life and survival of people with CF. The hepatobiliary manifestations in CF are various, with focal/multilobular biliary cirrhosis more common in children and porto-sinusoidal vascular disease (PSVD) in young adults. Portal hypertensive complications, particularly bleeding from esophagogastric varices and hypersplenism are common, while liver failure is rarer and mainly linked to biliary disease.

AREAS COVERED

This review explores current therapeutic options for CF-associated liver disease, presenting ongoing studies and new insights into parthenogenesis for potential future therapies.

EXPERT OPINION

Monitoring for signs of portal hypertension is essential. Limited evidence supports ursodeoxycholic acid (UDCA) efficacy in halting CF liver disease progression. The effect of cystic fibrosis transmembrane conductance regulator (CFTR) modulators on liver outcomes lacks definitive data, since patients with CF-related liver disease were excluded from trials due to potential hepatotoxicity. A proposed approach involves using UDCA and modulators in early stages, along with anti-inflammatory agents, with further therapeutic strategies awaiting randomized trials. Prevention of portal hypertensive bleeding includes endoscopic sclerotherapy or ligation of esophageal varices. Nonselective beta-blockers may also prevent bleeding and could be cautiously implemented. Other non-etiological treatments require investigation.

Elexacaftor/Tezacaftor/Ivacaftor use in Pediatric Cystic Fibrosis Patients with Advanced Liver Disease

BACKGROUND

Cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy extends the life expectancy of people with cystic fibrosis (PwCF). However, CFTR modulators have not been well studied in patients with cystic fibrosis liver disease (CFLD), specifically those with advanced liver disease with portal hypertension. The purpose of this report is to describe the use of elexacaftor/tezacaftor/ivacaftor (ETI) in pediatric CF patients with advanced CFLD.

METHODS

This retrospective case series included PwCF < 18 years old with baseline advanced CFLD initiated on ETI.

RESULTS

Eleven PwCF and advanced CFLD were treated with ETI; six started a reduced dose regimen. No patient required treatment interruption and four patients received dose changes related to increase in transaminase and/or bilirubin elevations. Mean (SD) change in ppFEV1 from prior to ETI to highest value during therapy was 14.27 % (4.25) (p = 0.007). When evaluating the group as whole, AST decreased from baseline to last reported -15.18 (23.23) units/L (p = 0.054) and ALT slightly increased 0.73 (39.13) units/L (p = 0.96). Bilirubin increased minimally overall for patients with mean change from baseline of 0.83 (1.33) mg/dL [range -0.5-3] (p = 0.17). A model for time on ETI showed a significant decrease in AST over time of 0.955 per month of ETI but no other liver biochemistries were significant. No patient experienced decompensation of CFLD.

CONCLUSION

ETI therapy in pediatric CF patients with advanced CFLD can be beneficial in improving pulmonary and nutritional outcomes without negative impact on liver biochemistries or hepatic outcomes. Close monitoring is recommended to ensure safety and tolerability.

Effects of elexacaftor/tezacaftor/ivacaftor on liver fibrosis markers in adults with cystic fibrosis

BACKGROUND

There are limited studies to date on the effects of elexacaftor/tezacaftor/ivacaftor (E/T/I) on markers of liver fibrosis in adults with cystic fibrosis (CF). This study aims to analyse changes in makers of liver fibrosis before and after initiation of E/T/I in CF adults.

METHODS

Outcome measures of liver fibrosis, including liver stiffness measurement (LSM) using FibroScan, AST-to-platelet-ratio index (APRI) and gamma-GT-to-platelet-ratio (GPR) were available in 74 CF adults following initiation of E/T/I. This was compared to historical data collected in 2018 prior to UK availability of E/T/I.

RESULTS

The median duration of E/T/I therapy at the time liver fibrosis markers were repeated was 21 (IQR: 17-25) months. There was an increase in APRI from historical measurement to follow-up but no change in LSM or GPR. There were no differences in change in fibrosis markers according to CF liver disease (CFLD) status, although those with a raised LSM at baseline (>6.8 kPa) (n = 14) had a significant reduction in LSM from historical measurement to follow-up versus those with a normal historical value (-3.3 kPa vs 0.25 kPa, p < 0.01).

CONCLUSIONS

Apart from APRI, we found no changes in liver fibrosis outcomes after initiation of E/T/I in adults with CF. Those with a historical diagnosis of CFLD had no significant worsening or improvement of liver fibrosis markers. We did observe a reduction in LSM in those with liver nodularity, with an initial highest result suggesting a potential positive treatment effect of E/T/I in this category of those with severe CFLD.

Stepwise Introduction of Elexacaftor-Tezacaftor-Ivacaftor in Patients With Cystic Fibrosis and Liver Cirrhosis Child-Pugh A or B Using Clinical and Therapeutic Drug Monitoring: A Case Series

PURPOSE

Cystic fibrosis (CF) is a monogenetic disease caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein and affecting multiple organs, including the lungs and liver. Almost 90% of people affected carry at least 1 Phe508del CFTR mutation. Medical treatment with the CFTR-modulating drug elexacaftor-tezacaftor-ivacaftor (ETI) has been proven to be efficacious in carriers of at least 1 Phe508del CFTR mutation. Use of ETI in patients with CF (pwCF) and liver cirrhosis is still controversial. Therefore, stepwise introduction of ETI in pwCF and liver cirrhosis Child-Pugh A or B was evaluated using clinical and therapeutic drug monitoring.

METHODS

Seven consecutive pwCF received ETI. Four dosing steps were defined, at each of which the patients underwent clinical examination, routine blood tests, and therapeutic drug monitoring. Exposure of elexacaftor, tezacaftor, and ivacaftor was assessed by means of determination of AUC.

FINDINGS

ETI was successfully introduced and maintained in all pwCF. In those with Child-Pugh B cirrhosis (n = 2), diminishment of the dose as recommended by the label resulted in AUC values that were lower than the mean AUC values in pwCF without hepatic impairment, as reported previously.

IMPLICATIONS

Despite the limitations of this small case series, stepwise elevation of ETI dose did not induce clinical adverse effects or increases in serum liver test results under strict clinical follow-up and therapeutic drug monitoring, and may allow tolerable introduction of this therapy in pwCF and cirrhosis Child-Pugh A and possibly B.

Changes in liver biochemistry and tacrolimus levels following the introduction of elexacaftor/tezacaftor/ivacaftor in patients with cystic fibrosis and liver transplant

INTRODUCTION

Elevated liver function tests (LFTs) are reported in individuals with cystic fibrosis (CF) starting elexacaftor/tezacaftor/ivacaftor (ETI). We report our experience with ETI in CF liver transplant patients.

METHOD

All CF liver transplant patients under the care of the Leeds CF team were commenced on ETI. Liver biopsies were performed when ALT >3 times upper limit of normal with or without bilirubin elevation. Treatment was guided by transplant hepatology and CF teams. Clinical data including lung function, LFTs and tacrolimus levels were collected.

RESULTS

Four patients (3 male, 1 female) on tacrolimus were commenced on ETI. Median time post liver transplantation was 6.5 years. Three patients underwent liver biopsy. One biopsy was abnormal with immune-mediated liver injury, which responded to increased immunosuppression. Management of tacrolimus levels proved straightforward.

CONCLUSION

ETI therapy in CF post liver transplant recipients was encouraging. Normal liver biopsy provides re-assurance to continue treatment despite elevated LFTs.

Cystic fibrosis liver disease in the post-modulator era

PURPOSE OF REVIEW

Highly effective modulators of cystic fibrosis transmembrane conductance regulator (CFTR) function have had dramatic impact on pulmonary and nutritional outcomes in persons with cystic fibrosis (pwCF). The impact on liver disease in pwCF was not the focus of the registration trials. The purpose of this review is to assess the current literature on the impact of HEMT on liver disease, progression, regression, and safety.

RECENT FINDINGS

Short-term studies of HEMT in pwCF have shown that there is no significant impact on the frequency of liver enzyme abnormalities. There is no evidence for significant improvement in liver enzymes over time on HEMT therapy. There is conflicting data on improvement in liver fibrosis determined by fibrosis indices (APRI and GPR) or elastography. One study showed improvement, and another showed worsening in younger (<20 years old) pwCF. There are reports of resolution or improvement in hepatic steatosis. There are rare reports of severe acute hepatitis and one report of hepatic decompensation leading to liver transplantation due to drug-induced liver disease.

SUMMARY

HEMT have not been shown to have a significant impact on improving liver disease or preventing fibrosis with short-term therapy. Longer studies are needed to assess the impact of HEMT on liver disease in pwCF.