Safety and efficacy comparisons of intravenous trastuzumab biosimilars to the reference product medicine in treatment-naïve and switch-over patients with breast cancer: a systematic and meta-analysis

Abstract

Aim

To compare the efficacy and safety of trastuzumab biosimilars to reference trastuzumab in patients with breast cancer. Trastuzumab, a biologic pharmaceutical product, has improved survival in hormone-oestrogen receptor 2 positive breast cancer. However, due to its high economic burden, ‘highly similar’ products known as biosimilars have been developed. Yet, concerns remain around the equivalency of efficacy and safety between biosimilars and their reference biologic.

Data Sources

A systematic review with meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. MEDLINE, EMBASE, and Cochrane Central databases were searched from inception to 26 April 2021 to obtain all randomised control trial data reporting on safety and efficacy outcomes of patients with breast cancer treated with trastuzumab biosimilars.

Study Selection

Studies were required to investigate and report on the safety and/or efficacy of trastuzumab. No restrictions were placed on study setting or intervention type and any study which reported at least one efficacy or safety outcome was included. A head-to-head comparison between the biosimilar and its reference biologic was not required for inclusion in the results. Only studies using randomised control trials were included. There was no restriction on the language the study was published in, and all abstracts, raw clinical trial data, and full-text studies were eligible.

Results

Forty-one studies were identified to report on patients treated with trastuzumab. The odds of achieving an overall response rate in patients treated with a trastuzumab biosimilar compared to the reference over at least 24 weeks of treatment was 1.10 (95% confidence interval [CI] 0.94–1.29). The proportion of patients experiencing any treatment emergent adverse events were comparable between the two study arms, 1.07 (95% CI 0.87–1.32). The switching group contained one study with 342 patients in the meta-analysis.

Conclusion

Trastuzumab biosimilars have comparable efficacy and safety to reference trastuzumab in treatment-naïve patients. However, evidence is lacking for switching patients from reference trastuzumab to biosimilars, so further work is required in the switch-over population.