Randomized, double-blind, placebo-controlled, phase I study of the safety and pharmacokinetics of namilumab in healthy Japanese and Caucasian men

Abstract

Namilumab is an investigational human monoclonal antibody to human granulocyte-macrophage colony-stimulating factor (GM-CSF). A phase I study of repeated namilumab dosing (150 or 300 mg subcutaneously) in non-Japanese patients with rheumatoid arthritis reported no safety concerns. The objective of this study was to report the safety (primary endpoint) and pharmacokinetic/pharmacodynamic effects of namilumab in healthy Japanese and Caucasian men aged 20-45 years (NCT02354599). 24 Japanese subjects were randomized to a single dose of namilumab (80, 150, or 300mg; n = 6/group) or placebo (n=6; 2subjects randomized/matched dose); 8 Caucasian subjects received namilumab 150mg (n=6) or placebo (n=2). Overall, 29 subjects completed the study (2 withdrew voluntarily; 1 due to a serious adverse event (AE) unrelated to treatment). Baseline demographics were similar across treatment groups; mean age and weight were higher in Caucasians. Namilumab was well tolerated, with no notable safety concerns or pharmacokinetic/pharmacodynamic differences between Japanese and Caucasian subjects. AEs were mild to moderate, with no dose-proportional increase in Japanese subjects. Area under the serum concentration-time curve from zero to infinity (AUC0-∞) and maximum serum concentration (Cmax) increased in a dose-proportional manner in Japanese subjects. AUC0-∞ was similar in Japanese (575.2µg×day/mL) and Caucasian (559.7µg×day/mL) 150-mg groups. Cmax was ~40% higher in Japanese subjects. Mean plasma total GM-CSF concentration-time profiles were similar in the Japanese and Caucasian 150-mg groups. Namilumab induced no clinically-relevant antibody response. Namilumab was well tolerated in Japanese and Caucasian subjects; namilumab 150 mg had similar pharmacokinetics in both populations, supporting further clinical development of this dose. .