Pegbelfermin in Patients With Nonalcoholic Steatohepatitis and Stage 3 Fibrosis (FALCON 1): A Randomized Phase 2b Study

Abstract

Background & aims: Pegbelfermin is a polyethlene glycol-conjugated analog of human fibroblast growth factor 21, a nonmitogenic hormone that regulates energy metabolism. This phase 2b study evaluated 48-week pegbelfermin treatment in patients with nonalcoholic steatohepatitis (NASH) and stage 3 (bridging) fibrosis.

Methods: The FALCON 1 study (NCT03486899) was a multicenter, randomized (1:1:1:1), double-blind, placebo-controlled study. Patients with biopsy-confirmed NASH and stage 3 fibrosis (N = 197) received weekly subcutaneous pegbelfermin (10, 20, or 40 mg) or placebo injections for 48 weeks. The week 24 primary endpoint was a ≥1-point decrease in fibrosis score without NASH worsening or NASH improvement without fibrosis worsening; pegbelfermin dose response was assessed using a Cochran-Armitage trend test across proportions (1-sided α = 0.05). Secondary/exploratory endpoints included histological and noninvasive measures of steatosis, fibrosis, and liver injury/inflammation.

Results: At week 24, the primary endpoint was met by 14% (placebo) vs 24%-31% (pegbelfermin arms); statistical significance was not reached due to lack of pegbelfermin dose response (P = .134). At weeks 24 and 48, more patients who received pegbelfermin had ≥30% relative reductions in hepatic fat fraction (magnetic resonance imaging-proton density fat fraction) vs placebo, although no differences reached statistical significance. In the pegbelfermin arms, improvements in liver fibrosis (magnetic resonance elastography and N-terminal type III collagen propeptide) and liver injury/inflammation (alanine aminotransferase, aspartate aminotransferase) were observed vs placebo. Adverse events occurred at similar frequencies across arms. No treatment-related serious adverse events were observed.

Conclusions: The FALCON 1 study did not meet its primary endpoint; a ≥1-point decrease in fibrosis score without NASH worsening or NASH improvement without fibrosis worsening assessed via biopsy. Pegbelfermin was generally well tolerated during 48 weeks of treatment.

Keywords: Bridging Fibrosis; FGF21; NASH.