A Phase 1 Study of the Pharmacokinetics, Safety, and Tolerability of Posdinemab (JNJ‐63733657) in Healthy Chinese Adults

Posdinemab, a humanized immunoglobulin G1/κ monoclonal antibody, binds with high affinity to phosphorylated tau protein which is associated with Alzheimer's disease (AD) pathophysiology. Posdinemab reduced tau seeding in murine models and was well tolerated in Phase-1 clinical studies. This open-label, single-arm, Phase-1 study examined the effects of posdinemab with single intravenous dose (60 mg/kg) in healthy adults from China. The main objectives were to assess posdinemab serum pharmacokinetics (PK, primary), safety and tolerability (secondary), and presence of anti-drug antibodies (ADAs; secondary). Results were compared with Phase-1 European first-in-human (NCT03375697) and Japanese (NCT03689153) studies. Healthy Chinese participants (N = 10), mean age 60.0 (SD 3.80) years and 60% female, received posdinemab. Mean posdinemab serum C_max was 1401 µg/mL, median t_max was 0.08 days, mean AUC_inf was 18162 µg·day/mL, mean CL was 3.36 mL/day/kg, and mean elimination t_1/2 was 17.5 days. Most participants (n = 8; 80%) experienced ≥1 treatment-emergent adverse event (TEAEs), most common (20%) of which were arthralgia and back pain. Four participants (40.0%) were positive for posdinemab ADAs post-dose with peak titers of 1:22.5 (n = 3) and 1:360 (n = 1). Serum posdinemab concentrations in ADA-positive and ADA-negative participants were generally comparable. In conclusion, PK profile of posdinemab in healthy participants from China was in the expected range and comparable to previous Phase-1 studies in Europe and Japan. There were no new safety concerns. These results support further global development of posdinemab in AD.