Phase 1 Clinical Trial of PPMX‐T003, a Novel Human Monoclonal Antibody Specific for Transferrin Receptor 1, to Evaluate Its Safety, Pharmacokinetics, and Pharmacodynamics

Abstract This study aimed to evaluate the safety, pharmacokinetics, and pharmacodynamics of PPMX‐T003, a novel human monoclonal antibody for transferrin receptor 1 (TFR1), in healthy individuals. Forty participants were enrolled and randomized to PPMX‐T003 dose groups (n = 6/group) and the placebo group (n = 10). The safety and pharmacokinetics profiles were assessed according to the sequential, ascending single‐dose intravenous infusions of PPMX‐T003 from 0.008 mg/kg to 0.25 mg/kg. Adverse events (AEs) after PPMX‐T003 administration occurred in 16 of 30 participants. Any severe AE and AE incidence were not reported, but they tended to increase depending on the dose. Laboratory tests, vital signs, and standard 12‐lead electrocardiogram showed no clinically relevant changes. Five participants experienced an infusion‐related reaction but recovered on days 5–10. Regarding pharmacokinetics, PPMX‐T003 has a nonlinear elimination pattern. PPMX‐T003 in the 0.25 mg/kg group showed apparent (>50%) decreased serum levels of reticulocytes from day 3 and sustained moderate (<10%) fall of hematocrit and hemoglobin counts from day 7. In conclusion, the antibody‐mediated blockade of TFR1 elicited the expected fall in blood cell levels and showed an acceptable safety profile, supporting the continuing development of PPMX‐T003 as a new candidate for polycythemia vera treatment.