Nonclinical evaluation of HS630, a proposed biosimilar of Trastuzumab Emtansine: Affinity, pharmacokinetics, and immunogenicity

Hui Jiang¹Jinjing Che^2,3*

• ¹School of Chemical Enginnering, Ocean Technology and Life Science, Dalian University of Technology, Dalian, China
• ²Laboratory of Advanced Biotechnology, Beijing Institute of Pharmacology and Toxicology, Beijing, China
• ³Beijing Institute of Microbiology and Epidemiology, Beijing Institute of Pharmacology and Toxicology, Beijing, China

Objective: To evaluate the similarity of affinity, pharmacokinetics, and immunogenicity shared by HS630 and trastuzumab emtansine (T-DM1). Methods: In vitro, the affinity was tested by using a Biacore™T200 apparatus. In vivo studies were conducted on tumor-bearing mice and cynomolgus monkeys in the context of different dosages and frequencies of administration. Double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) was used to determine the concentration of total antibody [including naked antibody and antibody-drug conjugate(ADC)] and the ADC of HS630 and Kadcyla®. Furthermore, HPLC-MS/MS was used to determine the concentration of free DM1. The bridge ELISA method was performed to determine anti-drug antibody for immunogenicity analysis. Results: In vitro, HS630 and Kadcyla® exhibited similar binding affinities for the human epidermal growth factor receptor 2 (HER2), with KD values of 6.372 E-11M and 9.424 E-11 M, respectively. After injected with 10 mg·kg⁻¹ of HS630 and Kadcyla® in tumor-bearing mice, the concentration of total antibody and ADC in serum reached its peak concentration at 5 minutes, and the concentration of total antibody reached its peak concentration at 24 hours in tumor. Meanwhile, in cynomolgus monkeys, the concentration of total antibody and ADC of HS630 exhibited non-linear pharmacokinetic characteristics following single intravenous administration of HS630 at 0.33 mg·kg-1, 1 mg·kg-1, and 3 mg·kg-1, respectively. Furthermore, no significant drug accumulation was observed after continuous intravenous administration 3 mg·kg⁻¹ HS630. Biosimilarity evaluation showed that HS630 met the criteria for Cmax and AUC(0-t) geometric mean ratios with Kadcyla® in the serum of tumor-bearing mice, as well as tumor and serum of cynomolgus monkey. No anti-drug antibody was detected in the serum samples obtained from cynomolgus monkeys after intravenous administration of HS630 and Kadcyla®. This is a provisional file, not the final typeset article Conclusion: HS630 and originator drug Kadcyla® exhibit pharmacokinetic similarity in tumor-bearing mice and cynomolgus monkeys following intravenous infusion. Comprehensive nonclinical evaluations of this study provide robust evidence for regulatory approval, in addition to the addressing of key scientific and technical challenges in biosimilar development.