QL1701 (a proposed trastuzumab biosimilar) versus reference trastuzumab plus docetaxel as first-line therapy for HER2-positive metastatic breast cancer: a multicenter, randomized, double-blinded, parallel-controlled, phase III equivalence trial

Background: QL1701 is a proposed biosimilar to the reference trastuzumab (Herceptin®). This trial compared the efficacy and safety of QL1701 with the reference trastuzumab in first-line treatment of human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer.

Materials and methods: This randomized, double-blinded, parallel-controlled, phase III equivalence trial was conducted in 73 centers in China. Eligible patients with histologically or cytologically diagnosed HER2-positive metastatic breast cancer were randomly assigned (1 : 1) to receive either QL1701 or reference trastuzumab in combination with docetaxel (every 3 weeks) for eight cycles as the first-line treatment. Then, in patients with objective responses or stable disease, the QL1701 or reference trastuzumab with or without docetaxel was maintained for totally up to 12 months if tolerated. The primary endpoint was 24-week objective response rate (ORR) assessed by an independent review committee (IRC). The equivalence margin was 0.80-1.25 with a 90% confidence interval (CI) for the ORR ratio (QL1701 to reference trastuzumab).

Results: Between 29 April 2020 and 15 March 2022, 474 patients were randomized, and 473 received either QL1701 (n = 236) or reference trastuzumab (n = 237). The risk ratio for 24-week ORR was 1.07 (90% CI 0.94-1.21). The 90% CI fell within the pre-specified equivalence margin of 0.80-1.25. The 24-week ORR assessed by IRC was 59.7% (95% CI 53.2% to 66.1%) versus 56.1% (95% CI 49.5% to 62.5%) in QL1701 and the reference trastuzumab, respectively. As of 12 April 2023, there were no notable differences in progression-free survival (median: 8.3 versus 8.4 months) and overall survival (1-year rate: 95.1% versus 93.3%) between the two groups. Safety, pharmacokinetic (PK), and immunogenicity profiles were similar between the two groups.

Conclusion: QL1701 demonstrated equivalent efficacy and similar safety to the reference trastuzumab when combined with docetaxel in the first-line treatment of patients with HER2-positive metastatic breast cancer, with similar PK and immunogenicity profiles.