Population Pharmacokinetics of Epcoritamab Following Subcutaneous Administration in Relapsed or Refractory B Cell Non-Hodgkin Lymphoma: PPK of Epcoritamab SC in R/R B-NHL

Background and Objectives Epcoritamab is a CD3xCD20 bispecific antibody approved for the treatment of adults with different types of relapsed or refractory (R/R) B cell non-Hodgkin lymphoma (B-NHL) after ≥ 2 lines of systemic therapy. Here we report the first results from a population pharmacokinetic model–based analysis using data from 2 phase 1/2 clinical trials (EPCORE ® NHL-1, NCT03625037 and EPCORE NHL-3, NCT04542824) evaluating epcoritamab in patients with R/R B-NHL. Methods Plasma concentration–time data included 6819 quantifiable pharmacokinetic samples from 327 patients with R/R B-NHL. A wide range of subcutaneous epcoritamab doses, 0.004–60 mg, was explored, with most patients ( n = 298) following the approved dosing regimen: step-up dose (SUD) 1 of 0.16 mg on cycle 1 day 1 and SUD 2 of 0.8 mg on cycle 1 day 8, followed by a full dose of 48 mg administered weekly during cycles 1–3, biweekly in cycles 4–9, and every 4 weeks thereafter. Each cycle lasted 28 days. The data were analyzed using nonlinear mixed-effects modeling. Results Quasisteady-state approximation of a two-compartment target-mediated drug disposition model with first-order absorption adequately characterized pharmacokinetics of epcoritamab following subcutaneous administration. After the first full dose and at the end of the weekly dosing regimen (end of cycle 3), the estimated median time to maximum concentration ( t max ) was 4 and 2.3 days, respectively. Age and body weight were significant covariates on the pharmacokinetics of epcoritamab. The geometric mean (coefficient of variation [CV], %) of the apparent total volume of distribution was 25.6 L (82%) for patients with R/R large B cell lymphoma in EPCORE NHL-1. Epcoritamab elimination exhibited nonlinear characteristics, with exposure increasing more than proportionally over 1.5–48 mg doses. The geometric mean (CV%) values of apparent total clearance and terminal half-life were 0.53 L/day (40%) and 22 days (58%), respectively, at the end of cycle 3 for the 48 mg full dose. Clinical data analyses did not identify any association between assessed characteristics, including body weight or age, and clinical efficacy or safety. After accounting for body weight, no clinically significant differences in epcoritamab pharmacokinetics were observed for sex, race, renal or hepatic function, or other disease characteristics. Age was not found to significantly affect epcoritamab pharmacokinetic exposure. Antidrug antibodies developed in 4