Six Year Data for IBAT Inhibitor Treatment for Alagille Syndrome

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RJ Sokol et al. Hepatology 2023; 78: 1698-1710. Open Access! Predictors of 6-year event-free survival in Alagille syndrome patients treated with maralixibat, an ileal bile acid transporter inhibitor

In this study, the authors examined 43 potential predictors of outcomes in pediatric patients (n=76) treated with maralixibat (MRX). The median duration of MRX treatment was 4.7 years. Key findings:

  • There were 10 liver transplantations, 3 decompensations, 2 deaths, and 1 surgical biliary diversion; thus, 16/76 (21%) had liver-related events.
  • The 6-year event-free survival improved with a clinically meaningful >1-point ItchRO(Obs) reduction from baseline to W48 (88% vs. 57%; p = 0.005), W48 bilirubin < 6.5 mg/dL (90% vs. 43%; p < 0.0001), and W48 serum bile acid < 200 µmol/L (85% vs. 49%; p = 0.001). These parameters were also predictive of 6-year transplant-free survival.
  • In this cohort, younger children (<36 months) fared worse, though this was likely related to selection bias as they had more severe cholestasis. In the discussion, the authors note that in their cohort, “there is a survivor bias such that older children are inherently healthier or they would have already undergone transplantation.”
  • Improved event-free survival could be largely related to symptomatic improvement. Many kids with Alagille require transplantation due to refractory pruritus. Since this study did not include histology or noninvasive techniques to assess hepatic fibrosis, it is unclear if there was also improvement in underlying liver function/fibrosis subsequent to reduction in toxic bile acid retention.
  • 46/76 (61%) had improvement in pruritus, 52/76 (68%) had improvement in bilirubin, and 56/76 (74%) had improvement in serum bile acids.

In their discussion, the authors note that in the GALA study, “which included natural history data from >1400 patients, 358 patients required a liver transplant, with 69% being transplanted for intractable pruritus.4“

My take: In patients with moderate to severe pruritus, patients who respond to IBAT inhibitors are likely to have improvement in important clinical outcomes.

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