Pilot study with IBAT inhibitor A4250 for the treatment of cholestatic pruritus in primary biliary cholangitis

Pruritus is a common complication of cholestatic liver diseases. Inhibition of the ileal bile acid transporter (IBAT/ASBT) may emerge as treatment option. Our aim was to assess tolerability and effect on pruritus of the selective IBAT inhibitor A4250 in patients with primary biliary cholangitis (PBC). Ten patients with PBC and bile acid sequestrant treatment of cholestatic pruritus were after a two-week wash out of the bile acid sequestrant treated with either 0.75 mg (n = 4) or 1.5 mg (n = 5) of A4250 for four weeks. Patients' pruritus was assessed by Visual Analogue Scale (VAS), 5-D itch scale and the pruritus module of the PBC40 questionnaire. Plasma bile acids and 7α-hydroxy-4-cholesten-3-one were measured by UPLC-MS/MS, plasma fibroblast growth factor 19 by ELISA, and serum autotaxin activity by homemade assay. All nine patients exposed to A4250 reported a remarkable improvement in pruritus, until none or mild according to 5-D itch, VAS and PBC40 pruritus. Five patients finished the study prematurely due to abdominal pain (5/5) and diarrhoea (4/5). The high incidence of probably bile acid malabsorption-related diarrhoea and abdominal pain in the bile acid sequestrant pre-Treated population indicates that the start dose of A4250 may have been too high for adult patients.