Efficacy and Safety of Biosimilar Trastuzumab (HLX02) in Patients with HER2-positive Advanced Breast Cancer: A Retrospective Real-world Analysis

Xuan Ye¹Linlin Wang²Wensheng Liu¹Mengmeng Wang¹Zihan Guo¹Han Shan¹Qing Zhai^1*Qiong Du^1*

• ¹Fudan University Shanghai Cancer Center, shanghai, China
• ²Fudan University Shanghai Cancer Center Xiamen Hospital, Xiamen, China

HLX02 is the first China-manufactured trastuzumab biosimilar. Few data are currently available about HLX02 in clinical practice. This study was designed to evaluate the real-world safety and efficacy of HLX02 in patients with HER2-positive metastatic breast cancer (MBC), as well as assessed the effectiveness of switching from trastuzumab originator (Herceptin ® ) to HLX02 during treatment.Between April 2021 and October 2022, all patients with HER-2-positive MBC who received at least one cycle of HLX02 at Fudan University Shanghai Cancer Center were included in a retrospective analysis. Patients were divided into two groups: the naïve group (patients treated with HLX02 from the beginning) and the switched group (patients who switched from Herceptin ® to HLX02). Efficacy evaluation and adverse events were compared between the two groups.A total of 124 eligible patients were finally included, with 80 patients (64.5%) in the naïve group, 44 patients (35.5%) in the switched group. The follow-up ranged from 0.7 to 40.2 months, the effectiveness rates were 57.5% in the naïve group and 54.5% in the switched group, respectively (P=0.751). The estimated median progression-free survival (PFS) were 13.70 (95% CI: 8.634-18.766) months and 14.70 (95% CI: 6.684-22.716) months in the naive and switched groups, respectively (P=0.192). Multivariate cox regression analysis suggested that brain metastasis and the current number of treatment lines were independent predictors of MBC PFS.Compared with first-line treatment, second-line treatment and third-or later-line treatment increased the disease risk by 2.095 times (95% CI: 1.043-4.210, P=0.038) and 3.035 times (95% CI :1.751-5.262, P<0.001), respectively. The incidence and distribution of treatment-emergent adverse events (TEAEs) occurrence between the two groups were relatively similar, with no significant statistical difference.HLX02 demonstrated favorable efficacy and safety in real-world practice comparable to those observed in previous HLX02 studies. Switching between trastuzumab originator and biosimilar for MBC treatment had no impact on efficacy and did not increase safety risks.