Pharmacokinetics and safety of sirukumab following a single subcutaneous administration to healthy Japanese and Caucasian subjects.

Objective: Sirukumab (CNTO 136) is a human mAb with high affinity and specificity for binding to interleukin-6. This Phase 1 study evaluated the pharmacokinetics, immunogenicity, safety, and tolerability of sirukumab following a single subcutaneous (s.c.) administration in healthy male Japanese and Caucasian subjects.

Methods: Japanese and Caucasian subjects were randomized to placebo or 25, 50, or 100 mg sirukumab. Blood samples were collected to measure serum sirukumab concentration and antibodies to sirukumab. Noncompartmental analysis and population pharmacokinetic modeling were conducted to characterize sirukumab pharmacokinetics. Adverse events were monitored at each visit.

Results: 25 Japanese and 24 Caucasian subjects received sirukumab and were included in the pharmacokinetic evaluation. Mean Cmax and AUC0-∞of sirukumab increased in an approximately dose-proportional manner in both Japanese and Caucasian subjects. Median tmax was 3 -5 days after s.c. administration of sirukumab. Mean t1/2 was 15 -16 days in Japanese and 15 -18 days in Caucasian subjects. A one-compartment population pharmacokinetic model adequately described sirukumab pharmacokinetics following s.c. administration. The estimated population means for CL/F, V/F, and Ka were 0.54 ±0.03 l/day, 12.2 ±0.55 l, and 0.77 ±0.07 day-1, respectively. Race was not a significant covariate on CL/F or V/F. No subject was positive for antibodies to sirukumab. Adverse events were generally mild and did not appear to be dose-related or lead to study discontinuation.

Conclusions: Sirukumab pharmacokinetics following subcutaneous administration was linear at doses ranging 25 -100 mg and was comparable between Japanese and Caucasian subjects. A single subcutaneous administration of 25, 50, or 100 mg sirukumab appeared to be well tolerated by both Japanese and Caucasian healthy male subjects.