Efficacy and Safety of BP02 (Trastuzumab Biosimilar) in HER2-Positive Metastatic Breast Cancer: A Multicenter Phase III Study

Trastuzumab targets human epidermal growth factor receptor 2 (HER2) receptors and is indicated for treating HER2-positive metastatic breast cancer. BP02, a recombinant IgG1 kappa humanized monoclonal antibody, is being developed as a trastuzumab biosimilar. The objective of this study was to evaluate the equivalence of BP02 with reference trastuzumab (RT: Herceptin^®-EU) in patients with HER2-positive metastatic breast cancer.

This double-blinded, 1:1 randomized, parallel-group, active-controlled, phase III equivalence trial recruited women aged 18–75 years with histologically/cytologically confirmed HER2- positive, locally recurrent or metastatic breast cancer with systemic metastasis, from 59 sites in India. Patients were randomly allocated 1:1 stratified by estrogen receptor/progesterone receptor status to receive BP02/RT (8-mg/kg loading dose on day 1-cycle 1, 6 mg/kg on day 1-cycles 2–8, of each 3-week cycle) combined with docetaxel (75 mg/m² on day 1-cycles 1–8) [induction phase]. Participants with complete or partial response, or stable disease at the end of the induction phase continued the study drug until disease progression/treatment discontinuation [maintenance phase]. The primary efficacy endpoint was the objective response rate per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1.

Between 23 September, 2020 and 16 September, 2022, 690 patients were recruited (n = 345 each to BP02/RT). At the end of the induction phase (intent-to-treat population), a similar proportion of patients achieved an objective response rate with BP02 (n = 231 [67.0%], 95% confidence interval [CI] 62.0, 71.9) and RT (n = 238 [69.0%], 95% CI 64.1, 73.9). The 95% CI of risk difference (−2.03, 95% CI −9.15, 5.09) and 90% CI of risk ratio (0.97, 90% CI 0.89, 1.06) were within equivalence margins of ± 13% and (0.80, 1.25), respectively. Treatment-emergent adverse events leading to treatment withdrawal were reported in 2.9% and 3.2% patients with BP02 and RT, respectively.

BP02 showed an equivalent efficacy and similar safety profile to RT at the end of 24 weeks.

CTRI Number: CTRI/2020/04/024456.