A phase 2 trial of short-term intravenous N-acetylcysteine in biliary atresia after Kasai portoenterostomy.

Background: For infants with biliary atresia, the only treatment that can establish bile flow and delay need for liver transplant is the Kasai portoenterostomy (KP). Unfortunately, the KP has variable success. In this study, we hypothesized that intravenous N-acetylcysteine (IV NAC) treatment following KP would improve bile flow.

Methods: This was a phase 2 study following the two-stage "minimax" trial design. Participants received IV NAC (150 mg/kg/day) for 7 days after KP, and the primary endpoint was achieving total serum bile acids (TSBA) ≤10 μmol/L within 24 weeks of KP. Secondary endpoints were clinical markers and the occurrence of sentinel events.

Results: There were 12 participants in stage 1 who received treatment, with none achieving TSBAs ≤10 μmol/L within 24 weeks of KP. As a result, no participants were enrolled in stage 2. There were 32 adverse events in 11 participants, including 5 serious adverse events which were considered part of the participants' natural clinical course and not directly attributable to NAC treatment. Analyses of secondary outcomes demonstrated no difference in clinical markers or occurrence of sentinel events between study participants and matched historical controls.

Conclusions: This study demonstrates how the two-stage "minimax" trial design can be used to efficiently evaluate potential therapies for BA. Although the primary endpoint was not met, NAC therapy was generally well-tolerated. NAC therapy may prove efficacious in future trials with (i) a less stringent primary endpoint and/or (ii) a longer course of treatment (NCT03499249).