Population pharmacokinetic and exposure–response analyses of elotuzumab plus pomalidomide and dexamethasone for relapsed and refractory multiple myeloma

Abstract Purpose Elotuzumab plus pomalidomide/dexamethasone (E-Pd) demonstrated efficacy and safety in relapsed and refractory multiple myeloma (RRMM). The clinical pharmacology of elotuzumab [± lenalidomide/dexamethasone (Ld)] was characterized previously. These analyses describe elotuzumab population pharmacokinetics (PPK), the effect of Pd, and assess elotuzumab exposure–response relationships for efficacy and safety in patients with RRMM. Methods A previously established PPK model was updated with E-Pd data from the phase 2 ELOQUENT-3 study (NCT02654132). The dataset included 8180 serum concentrations from 440 patients with RRMM from 5 clinical trials. Elotuzumab PK parameter estimates were used to generate individual daily time-varying average concentrations (daily C avg ) for multi-variable time-to-event exposure–response analyses of progression-free survival (PFS) and time to the first occurrence of grade 3 + adverse events (AEs) in RRMM. Results Elotuzumab PK were well-described by a two-compartment model with parallel linear and Michaelis–Menten elimination from the central compartment (V max ) and non-renewable target-mediated elimination from the peripheral compartment (K int ). Co-administration with Pd resulted in a 19% and 51% decrease in elotuzumab linear clearance and K int , respectively, versus Ld; steady-state exposures were similar. V max increased with increasing serum M-protein. Hazard ratios (95% confidence intervals) for daily C avg were 0.9983 (0.9969–0.9997) and 0.9981 (0.9964–0.9998) for PFS and grade 3 + AEs, respectively. Conclusions The PPK model adequately described the data and was appropriate for determining exposures for exposure–response analyses. There were no clinically relevant differences in elotuzumab exposures between Pd and Ld backbones. In ELOQUENT-3, increasing elotuzumab daily C avg prolonged PFS without increasing grade 3 + AEs.