Population Pharmacokinetics and Pharmacodynamics of Pegozafermin in Patients with Nonalcoholic Steatohepatitis

Pegozafermin is a long-acting glycoPEGylated analog of fibroblast growth factor 21 (FGF21) in development for the treatment of nonalcoholic steatohepatitis (NASH) and severe hypertriglyceridemia. In a phase Ib/IIa placebo-controlled, double-blind, multiple ascending dose study in patients with NASH (NCT04048135), administration of pegozafermin resulted in clinically meaningful reductions in hepatic fat fraction (HFF), with a favorable safety and tolerability profile. We aimed to characterize the relationship between pegozafermin dosing, exposure and effects on HFF reduction. We used pharmacokinetic (PK) and pharmacodynamic (PD) modeling of data from the phase Ib/IIa study to identify model parameters and covariates affecting the exposure-response relationship. Clinical simulations were performed to help support dose selection for larger studies. Pegozafermin exposure was adequately described by a one compartment PK model, with one additional transit absorption compartment. PK/PD modeling demonstrated that HFF reduction was significantly related to pegozafermin exposure. HFF outcomes were correlated with average pegozafermin concentrations regardless of weekly dosing (q.w.) or dosing every 2 weeks (q2w). The significant PK/PD model covariates included baseline body weight, alanine aminotransferase level, and liver volume. Simulations showed that the 30 mg q.w. dose approximated the full PD effect; almost all patients would benefit from a greater than or equal to 30% HFF reduction, suggesting fibrosis regression. Furthermore, 44 mg q2w dosing (~22 mg q.w.) appeared to be an effective regimen for HFF reduction. Our modeling supports the feasibility of q.w. and q2w dosing for achieving favorable treatment outcomes in patients with NASH, and provides the rationale for dose selection for the phase IIb ENLIVEN study (NCT04929483).