Mechanism-Based Pharmacokinetic/Pharmacodynamic Modeling of Erythroferrone in Anemic Rats with Chronic Kidney Disease and Chemotherapy-Induced Anemia: An Early Biomarker for Hemoglobin Response and rHuEPO Hyporesponsiveness.

Erythroferrone (ERFE) has emerged as a potential biomarker for the erythropoiesis response following recombinant human erythropoietin (rHuEPO) treatment. While the association between ERFE and hemoglobin (HGB) response to rHuEPO is well-established in nonanemic conditions, such correlation and ERFE kinetics in anemic states remain unclear. We employed two rat models of anemia, chronic kidney disease (CKD) anemia and chemotherapy-induced anemia (CIA), to determine ERFE kinetics and its correlation with HGB responses after rHuEPO administration. The key factors influencing ERFE kinetics were characterized using a PK/PD modeling approach and supported by experimentation. Following rHuEPO injection, ERFE induction was diminished in anemic rats compared with that of healthy rats, primarily attributed to the reduced precursor cell mass and impaired rHuEPO responsiveness. The early increase in ERFE at 4 h post administration allows for the prompt prediction of HGB response and rHuEPO hyporesponsiveness in anemic rats. Consequently, the ERFE-based dose adjustment resulted in a rHuEPO-sparing effect in CKD rats. This strategy is expected to be translatable to anemic patients, potentially reducing rHuEPO doses and mitigating HGB overshooting.