Pegbelfermin selectively reduces secondary bile acid concentrations in patients with non-alcoholic steatohepatitis

Abstract

Background & aims: Increased serum bile acids (BAs) have been observed in patients with non-alcoholic steatohepatitis (NASH). Pegbelfermin (PGBF), a polyethylene glycol-modified (PEGylated) analogue of human fibroblast growth factor 21 (FGF21), significantly decreased hepatic steatosis and improved fibrosis biomarkers and metabolic parameters in patients with NASH in a phase IIa trial. This exploratory analysis evaluated the effect of PGBF on serum BAs and explored potential underlying mechanisms.

Methods: Serum BAs and 7α-hydroxy-4-cholesten-3-one (C4) were measured by HPLC-mass spectrometry (MS) using serum collected in studies of patients with NASH (NCT02413372) and in overweight/obese adults (NCT03198182) who received PGBF. Stool samples were collected in NCT03198182 to evaluate faecal BAs by liquid chromatography (LC)-MS and the faecal microbiome by metagenetic and metatranscriptomic analyses.

Results: Significant reductions from baseline in serum concentrations of the secondary BA, deoxycholic acid (DCA), and conjugates, were observed with PGBF, but not placebo, in patients with NASH; primary BA concentrations did not significantly change in any arm. Similar effects of PGBF on BAs were observed in overweight/obese adults, allowing for an evaluation of the effects of PGBF on the faecal microbiome and BAs. Faecal transcriptomic analysis showed that the relative abundance of the gene encoding choloylglycine hydrolase, a critical enzyme for secondary BA synthesis, was reduced after PGBF, but not placebo, administration. Furthermore, a trend of reduction in faecal secondary BAs was observed.

Conclusions: PGBF selectively reduced serum concentrations of DCA and conjugates in patients with NASH and in healthy overweight/obese adults. Reduced choloylglycine hydrolase gene expression and decreased faecal secondary BA levels suggest a potential role for PGBF in modulating secondary BA synthesis by gut microbiome. The clinical significance of DCA reduction post-PGBF treatment warrants further investigation.

Lay summary: Pegbelfermin (PGBF) is a hormone that is currently being studied in clinical trials for the treatment of non-alcoholic fatty liver disease. In this study, we show that PGBF treatment can reduce bile acids that have previously been shown to have toxic effects on the liver. Additional studies to understand how PGBF regulates bile acids may provide additional information about its potential use as a treatment for fatty liver.

Keywords: ALT, alanine aminotransferase; AST, aspartate aminotransferase; ApoA1, apolipoprotein A1; BA, bile acid; BSH, bile salt hydrolase; Bile salt hydrolase; Biomarkers; C4; C4, 7α-hydroxy-4-cholesten-3-one; CA, cholic acid; CDCA, chenodeoxycholic acid; CYP7A1, cytochrome P450 7A1; DCA, deoxycholic acid; Deoxycholic acid; FGF21; FGF21, fibroblast growth factor 21; FXR, farnesoid X receptor; GCA, glyco-cholic acid; GCDCA, glyco-chenodeoxycholic acid; GDCA, glyco-deoxycholic acid; GUDCA, glyco-ursodeoxycholic acid; HFF, hepatic fat fraction; HbA1c, glycated haemoglobin; LC, liquid chromatography; LCA, lithocholic acid; MS, mass spectrometry; Microbiome; NAFLD, non-alcoholic fatty liver disease; NASH, non-alcoholic steatohepatitis; PEGylated, polyethylene glycol-conjugated; PGBF, pegbelfermin; PRO-C3, N-terminal type III collagen propeptide; QD, once daily; QW, once weekly; T2DM, type 2 diabetes mellitus; TCA, tauro-cholic acid; TCDCA, tauro-chenodeoxycholic acid; TDCA, tauro-deoxycholic acid; UDCA, ursodeoxycholic acid; baiCD, 7α-hydroxy-3-oxo-delta4-cholenoic acid oxidoreductase; baiH, 7β-hydroxy-3-oxo-delta4-cholenoic acid oxidoreductase; hdhA, 7-alpha-hydroxysteroid dehydrogenase.

Graphical abstract

Fig. 1

Change in serum concentration of secondary BAs in patients with NASH. (A) Percentage and (B) absolute change in serum concentration of DCA + conjugates in patients from study NCT02413372. In (A), error = bootstrapped 95% CI; in (B), whiskers extend to most extreme data point that is ≤1.5× the IQR from the box. BA, bile acid; D, day; DCA, deoxycholic acid; GDCA, glyco-deoxycholic acid; NASH, non-alcoholic steatohepatitis; PGBF, pegbelfermin; QD, once daily; QW, once week; TDCA, tauro-deoxycholic acid.

Fig. 2

Percentage change in primary BA concentrations in patients with NASH. Percentage change in serum primary BA concentrations in patients from study NCT02413372; error = bootstrapped 95% CI. BA, bile acid; CA, cholic acid; CDCA, chenodeoxycholic acid; D, day; GCA, glyco-cholic acid; GCDCA, glyco-chenodeoxycholic acid; NASH, non-alcoholic steatohepatitis; PGBF, pegbelfermin; QD, once daily; QW, once weekly; TCA, tauro-cholic acid; TCDCA, tauro-chenodeoxycholic acid.

Fig. 3

Effects of PGBF on total DCA + conjugates, total primary BAs, and total BAs in patients with NASH. (A) Percentage change from baseline of DCA + conjugates and total primary BAs; error = bootstrapped 95% CI. (B) Fraction of DCA + conjugates and total primary BAs relative to total serum BAs. (C) Percentage change from baseline total serum BAs from study NCT02413372. Whiskers extend to most extreme data point that is ≤1.5× the IQR from the box. BA, bile acid; D, day; DCA, deoxycholic acid; NASH, non-alcoholic steatohepatitis; PGBF, pegbelfermin; QD, once daily; QW, once weekly.

Fig. 4

Effects of PGBF on C4 concentration and LDL/HDL ratio in patients with NASH. (A) Percentage and (B) absolute change in C4. (C) Percentage change in LDL/HDL ratio. (D) Correlation between percentage change in C4 from baseline to Day 112 and percentage change in LDL/HDL ratio from baseline to Day 112 from study NCT02413372. In (A), error = bootstrapped 95% CI; in (B and C), whiskers extend to most extreme data point that is ≤1.5× the IQR from the box. C4, 7α-hydroxy-4-cholesten-3-one; D, day; NASH, non-alcoholic steatohepatitis; PGBF, pegbelfermin; QD, once daily; QW, once weekly.

Fig. 5

Percentage of primary and secondary BA concentrations in relation to the total BA pool in healthy overweight or obese adults. Total DCA + conjugates (DCA, GDCA, and TDCA) and total primary BAs (CA, GCA, TCA, CDCA, GCDCA, and TCDCA) as a percentage of the total BA pool from study NCT03198182. Median percentages for each arm at each time point are presented. Formal statistical analyses were not performed on these data because of the small sample size. BA, bile acid; CA, cholic acid; CDCA, chenodeoxycholic acid; D, day; DCA, deoxycholic acid; GCA, glyco-cholic acid; GCDCA, glyco-chenodeoxycholic acid; GDCA, glyco-deoxycholic acid; PGBF, pegbelfermin; QW, once weekly; TCA, tauro-cholic acid; TCDCA, tauro-chenodeoxycholic acid; TDCA, tauro-deoxycholic acid.

Fig. 6

Effects of PGBF on faecal levels of choloylglycine hydrolase (BSH) gene, DCA, and LCA in healthy overweight or obese adults. (A) Relative faecal levels of choloylglycine hydrolase gene. (B) Percentage change from baseline to Day 15 in relative faecal choloylglycine hydrolase gene levels. (C) Faecal DCA and LCA levels at baseline and Day 15. (D) Percentage change from baseline to Day 15 in faecal DCA and LCA levels from study NCT03198182. Whiskers extend to most extreme data point that is ≤1.5× the IQR from the box. BSH, bile salt hydrolase; D, day; DCA, deoxycholic acid; LCA, lithocholic acid; PGBF, pegbelfermin; QD, once daily; QW, once weekly.