Unveiling Hepatic Protein Alterations in Neonatal and Infant Biliary Atresia

Pediatric populations differ from adults in drug elimination capacity. While current scaling methods account for enzyme and transporter maturation, they overlook comorbidities, such as biliary atresia (BA), a liver disease appearing within the first 2-8 weeks of life that can progress to cirrhosis. Such conditions may impair hepatic drug clearance, requiring dose adjustments. Physiologically based pharmacokinetic (PBPK) tools aim to address such cases and have been advocated to fill gaps in clinical data instead of less formalized and evidence-based guesswork. However, the paucity of systems data in rare disease populations has hindered the development of robust PBPK models. This study used global liquid chromatography and tandem mass spectrometry (LC-MS/MS) proteomics to quantify drug-metabolizing enzymes and transporters in diseased neonatal (n = 13) and infant (n = 12) liver samples, revealing significant expression changes in biliary atresia (BA) livers vs. controls (n = 19). Based on cohort means, CYP2A6, CYP2B6, and CYP2E1 levels were 6-17-fold higher in BA livers compared to controls, while CYP4F11 and CYP20A1 were reduced. UGT1A1, UGT2B4, and UGT2B7 showed up to 16-fold higher abundance in neonates with BA. Among transporters, ABCF1 abundance increased dramatically (46-fold), whereas B3AT/SLC4A1, ADT1/SLC25A4, and S27A5/SLC27A5 were decreased. The observed alterations suggest that assuming similar liver function in BA and non-BA patients has implications, with impact varying by drug clearance pathway. While in silico models can explore this, clinical pharmacokinetic studies in BA are essential for verification. To our knowledge, such studies are absent. Our observations underscore the urgent need for dedicated pharmacokinetic studies in BA patients to improve precision dosing.