Acute Liver Failure in a Pediatric Patient with Congenital Dysery-Thropoietic Anemia Type I Treated with Deferasirox

Whole-exome sequencing for genetic diagnosis of idiopathic liver injury in children

Genome-wide approaches, such as whole-exome sequencing (WES), are widely used to decipher the genetic mechanisms underlying inter-individual variability in disease susceptibility. We aimed to dissect inborn monogenic determinants of idiopathic liver injury in otherwise healthy children. We thus performed WES for 20 patients presented with paediatric-onset recurrent elevated transaminases (rELT) or acute liver failure (ALF) of unknown aetiology. A stringent variant screening was undertaken on a manually-curated panel of 380 genes predisposing to inherited human diseases with hepatobiliary involvement in the OMIM database. We identified rare nonsynonymous variants in nine genes in six patients (five rELT and one ALF). We next performed a case-level evaluation to assess the causal concordance between the gene mutated and clinical symptoms of the affected patient. A genetic diagnosis was confirmed in four rELT patients (40%), among whom two carried novel mutations in ACOX2 or PYGL, and two had previously-reported morbid variants in ABCB4 or PHKA2. We also detected rare variants with uncertain clinical significance in CDAN1, JAG1, PCK2, SLC27A5 or VPS33B in rELT or ALF patients. In conclusion, implementation of WES improves diagnostic yield and enables precision management in paediatric cases of liver injury with unknown aetiology, in particular recurrent hypertransaminasemia.

Deferasirox-induced liver injury and Fanconi syndrome in a beta-thalassemia major male

A 33-year-old male presenting with subacute abdominal pain was found to have hyperbilirubinaemia, hypokalaemia and hyponatraemia. This was in the setting of transitioning between deferasirox iron chelator formulations, from dispersible tablets to film-coated tablets for ongoing treatment of chronic iron overload secondary to transfusion requirement for beta-thalassemia major. A liver biopsy demonstrated acute cholestasis with patchy confluent hepatocellular necrosis and mild to moderate microvesicular steatosis. Based on the histological, biochemical and clinical findings, the diagnosis of hepatotoxicity and Fanconi-like syndrome was made. The patient improved clinically and biochemically with cessation of the deferasirox film-coated tablets and supportive management. To our knowledge, this is the first case report of hepatotoxicity and Fanconi-like syndrome occurring due to deferasirox film-coated tablets with previous tolerance of dispersible deferasirox tablets. It is important to raise clinical awareness of this potentially severe complication.

The iron chelator Deferasirox causes severe mitochondrial swelling without depolarization due to a specific effect on inner membrane permeability

The iron chelator Deferasirox (DFX) causes severe toxicity in patients for reasons that were previously unexplained. Here, using the kidney as a clinically relevant in vivo model for toxicity together with a broad range of experimental techniques, including live cell imaging and in vitro biophysical models, we show that DFX causes partial uncoupling and dramatic swelling of mitochondria, but without depolarization or opening of the mitochondrial permeability transition pore. This effect is explained by an increase in inner mitochondrial membrane (IMM) permeability to protons, but not small molecules. The movement of water into mitochondria is prevented by altering intracellular osmotic gradients. Other clinically used iron chelators do not produce mitochondrial swelling. Thus, DFX causes organ toxicity due to an off-target effect on the IMM, which has major adverse consequences for mitochondrial volume regulation.

Effects of deferasirox dose and decreasing serum ferritin concentrations on kidney function in paediatric patients: an analysis of clinical laboratory data from pooled clinical studies

BACKGROUND

Serious and fatal deferasirox-induced kidney injury has been reported in paediatric patients. This study aimed to investigate the effects of deferasirox dose and serum ferritin concentrations on kidney function and the effect of impaired kidney function on dose-normalised deferasirox minimum plasma concentration (C_min).

METHODS

We did a case-control analysis using pooled data from ten clinical studies. We identified transfusion-dependent patients with thalassaemia, aged 2-15 years, who were receiving deferasirox and had available baseline and follow-up serum creatinine and ferritin measurements. Cases of acute kidney injury (AKI) were defined according to an estimated glomerular filtration rate (eGFR) threshold of 90 mL/min per 1·73 m² or less (if baseline eGFR was ≥100 mL/min per 1·73 m²), an eGFR of 60 mL/min per 1·73 m² or less (if baseline eGFR was <100 mL/min per 1·73 m²), or an eGFR decrease from baseline of at least 25%. Cases were matched to control visits (eGFR ≥120 mL/min per 1·73 m²) on age, sex, study site, and time since drug initiation. We calculated rate ratios for AKI using conditional logistic regression, and evaluated the effect of eGFR changes on C_min.

FINDINGS

Among 1213 deferasirox-treated paediatric patients, 162 cases of AKI and 621 matched control visits were identified. Patients with AKI had a mean 50·2% (SD 15·5) decrease in eGFR from baseline, compared with a 6·9% (29·8) decrease in controls. A significantly increased risk for AKI (rate ratio 1·26, 95% CI 1·08-1·48, p=0·00418) was observed per 5 mg/kg per day increase in deferasirox dispersible tablet dose (equivalent to a 3·5 mg/kg per day dose of film-coated tablets or granules), above the typical starting dose (20 mg/kg per day). An increased risk (1·25, 1·01-1·56, p=0·0400) for AKI was also observed per 250 μg/L decrease in serum ferritin, starting from 1250 μg/L. High-dose deferasirox (dispersible tablet dose >30 mg/kg per day) resulted in an increased risk (4·47, 1·25-15·95, p=0·0209) for AKI when serum ferritin was less than 1000 μg/L. Decreases in eGFR were associated with increased C_min.

INTERPRETATION

Deferasirox can cause AKI in a dose-dependent manner. The increased AKI risk with high-dose deferasirox and lower serum ferritin concentration is consistent with overchelation as a causative factor. Small decreases in eGFR correlate with increased deferasirox C_min, especially in younger patients. Physicians should closely monitor renal function and serum ferritin, use the lowest effective dose to maintain acceptable body iron burden, and interrupt deferasirox treatment when AKI or volume depletion are suspected.

FUNDING

None.

Significant Hyperbilirubinemia and Acute Hepatocellular Jaundice in a Pediatric Patient Receiving Deferasirox: A Case Report

Despite a boxed warning, postmarketing reports of deferasirox-associated hepatic injury in patients with chronic transfusions are not well described. Hepatic impairment, including failure, has been reported to occur more frequently in patients older than 55 years and in those with significant comorbidities, including liver cirrhosis and multiorgan failure. In this case report, we describe significant hyperbilirubinemia and acute hepatocellular jaundice related to deferasirox in a 7-year-old female being treated for iron overload secondary to chronic transfusions. This report outlines a unique case without preexisting risk factors in which other causes of liver injury are excluded as defined by the Roussel Uclaf Causality Assessment Method, which indicates a probable score of deferasirox causing the injury.

Fulminant Liver Failure in a Child With β-Thalassemia on Deferasirox: A Case Report

Deferesirox (DFX), an oral chelating agent, is used to treat chronic iron overload in several hematological diseases such as β-thalassemia, sickle cell disease, and myelodysplastic anemia. DFX is generally well tolerated with the exception of gastrointestinal disturbances and rash, although cases of renal toxicity, as well as acute and chronic liver failure, have been reported in adults and children. Here we describe a 3-year-old girl with β-thalassemia undergoing treatment with DFX who presented with acute liver failure and Fanconi's syndrome. It is important for pediatric gastroenterologists, hepatologists, and hematologists to be aware that the commonly used drug DFX can lead to acute liver failure in children, and liver function should be monitored closely in all patients taking DFX.

Acute Liver Failure During Deferasirox Chelation: A Toxicity Worth Considering

This case report details a unique case of acute, reversible liver failure in a 12-year-old male with sickle cell anemia on chronic transfusion protocol and deferasirox chelation. There is substantial literature documenting deferasirox-induced renal injury, including Fanconi syndrome, but less documentation of hepatic toxicity and few reports of hepatic failure. The case highlights the importance of close monitoring of ferritin, bilirubin, and transaminases for patients on deferasirox.