Posters Show Efficacy for Combination Therapies With Trastuzumab Biosimilars in Breast Cancer

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Two posters from San Antonio Breast Cancer Symposium 2023 found that combination therapies featuring trastuzumab biosimilars and other common cancer medicines were safe and effective in patients with breast cancer.

Comparison of Docetaxel Plus Trastuzumab Biosimilar vs Herceptin

A study comparing a combination treatment of docetaxel chemotherapy plus a biosimilar (TQ-B211) or reference trastuzumab (Herceptin) found equivalent efficacy, safety, and immunogenicity between the 2 trastuzumab products. The study contributed insight into the potential use of TQ-B211 in the treatment of HER2-positive metastatic breast cancer.

The analysis, conducted from December 6, 2018, to July 31, 2021, enrolled a total of 386 patients with HER2-positive breast cancer, 192 of whom were placed in the TQ-B211 group and 194 were put in the Herceptin group. In the intention-to-treat (ITT) population, besides the comparable overall response rates at 24 weeks, the disease control rate for TQ-B211 was 83.85%, and for Herceptin it was 78.35%, with no statistically significant difference between the 2 groups (P = .194). Progression-free survival showed no statistically significant difference by the data cutoff date of October 31, 2021 (P = .683), and the median overall survival (OS) was not reached in either group (P = .925).

The analysis of the per-protocol population yielded similar results to the ITT population, reinforcing the consistency of the findings. Rates of treatment-related grade 3 or higher adverse events were comparable between the TQ-B211 and Herceptin groups, at 41.05% and 46.39%, respectively.

Importantly, the study reported a low immunogenicity risk and magnitude in both groups. The occurrence of anti-drug antibodies was 0.53% for TQ-B211 and 0% for Herceptin, while neutralizing antibodies were negative in both groups.

HLX02 Combined With Pertuzumab and Chemotherapy

The study investigated the real-world evidence of HLX02 (Zercepac), the first manufactured trastuzumab biosimilar in China, when combined with pertuzumab and chemotherapy as a first-line treatment for HER2-positive advanced breast cancer. Phase 3 clinical trials previously confirmed its similar efficacy, safety, and immunogenicity compared to Herceptin. In this observational study at Beijing Cancer Hospital from April 2020 to April 2023, 55 patients (including 1 male) were included.

The primary outcome was progression-free survival (PFS), and secondary outcomes included overall survival, objective response rate, disease control rate (DCR), and adverse events. The results showed a median age of 57 years, with 36.4% of tumors being estrogen receptor-positive. Visceral metastasis was reported in 72.7% of patients, with the liver and lung being the most common sites. Objective response was observed in 80% of patients, leading to a DCR of 100%. HLX02 and pertuzumab were continued as maintenance therapy in 90.9% of patients.

With a median follow-up of 9.8 months, progressive disease occurred in 21.8% of patients, and no deaths were reported. The median PFS was 24.8 months, with 12-month and 18-month PFS rates of 84.0% and 58.8%, respectively. HLX02-related diarrhea and infusion-related reactions were reported in 3.6% and 1.8% of patients, respectively. No clinically significant decline in left ventricular ejection fraction or cardiac toxicity was observed.

In conclusion, HLX02 demonstrated comparable efficacy and safety to Herceptin when combined with pertuzumab and chemotherapy in real-world first-line treatment for Chinese patients with HER2-positive advanced breast cancer. The study suggests that HLX02 may provide another option for HER2-targeted therapy combined with pertuzumab for Chinese patients, and further investigation is needed to verify the long-term survival benefits.

Reference

1. Hu X, Zhang Q, Wang S, et al. Efficacy, safety, and immunogenicity of TQ-B211 (a trastuzumab biosimilar) plus docetaxel versus Herceptin® plus docetaxel for HER2-positive metastatic breast cancer: a double-blind, randomised, multicenter, phase 3 trial. Presented at: SABCS 2023; December 5-9, 2023; San Antonio, TX. Poster PO1-29-03

2. Zhang R, Song G, Liu X, Li H-P. Real-world first line use of trastuzumab biosimilar (HLX02), pertuzumab and chemotherapy for Chinese patients with HER2-positive metastatic breast cancer. Presented at: SABCS 2023; December 5-9, 2023; San Antonio, TX. Poster PO4-04-02