Trastuzumab Biosimilar (HLX02), Pertuzumab Plus Chemotherapy in Patients with HER2-Positive Metastatic Breast Cancer after Progression of Trastuzumab: A Prospective, Phase II Study.

ABSTRACT

PURPOSE: This study aims to evaluate the efficacy and safety of trastuzumab biosimilar (HLX02) in combination with pertuzumab and chemotherapy in patients with human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer (MBC) after progression of trastuzumab. MATERIALS AND METHODS: In this prospective, single-arm, phase II study, patients with HER2-positive MBC after progression of trastuzumab received pertuzuamb, HLX02, and chemotherapy in Beijing Cancer Hospital from March 2020 to December 2022. The primary endpoint was progression-free survival (PFS), and secondary endpoints included objective response rate (ORR), disease control rate (DCR), overall survival (OS), and safety. The study was registered with ClinicalTrials.gov (NCT05188495). RESULTS: A total of 45 patients were included in this study. Twelve patients (26.7%) were treated in second-line and 33 patients (73.3%) were in third-line and later setting. Eighty percent and 15.5% patients had previously received pyrotinib/lapatinib and T-DM1, respectively. With a median follow-up of 24.4 months (range, 1.2 to 43.9 months), the median PFS was 7.6 months (95% confidence interval, 4.3 to 10.9), OS was not reached, the ORR was 31.1%, and DCR was 91.1%. The treatment was well tolerated. CONCLUSION: The combination of trastuzumab biosimilar HLX02, pertuzumab, and chemotherapy exhibited promising efficacy and a favorable safety profile as second- and beyond-line treatment in HER2-positive MBC.