The following article features coverage from the European Society for Medical Oncology (ESMO) 2018 meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Biosimilars to trastuzumab in breast cancer were equivalent in terms of efficacy compared to the reference product in both early and metastatic breast cancer settings, according to a study that will be presented at the 2018 ESMO Congress in Munich, Germany.1

These results support extrapolation between clinical settings, the researchers concluded.

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A biosimilar to trastuzumab, trastuzumab-dkst (Ogivri™), was recently approved by the US Food and Drug Administration based on data showing physicochemical and functional biosimilarity and phase 3 efficacy and safety data in metastatic breast cancer. Additionally, clinical trials evaluating trastuzumab biosimilars for the treatment of ERBB2-positive breast cancer have assessed bioequivalence through comparative efficacy outcomes and neoadjuvant therapy for early-stage disease or as a first-line therapy for metastatic disease.

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Here, researchers conducted a review to examine if demonstrating bioequivalence in terms of efficacy is different for early-stage breast cancer compared with metastatic breast cancer. They identified abstracts and manuscripts using the terms “biosimilar” and “trastuzumab” between January 1, 2013, and March 14, 2018.  

Of 84 results identified, they selected 8 phase 3 clinical trials with comparative clinical efficacy results: 4 in early-stage disease and 4 in metastatic disease. These trials included data for 6 proposed biosimilars.

In all of the trials included in the analysis, the proposed biosimilar demonstrated equivalent in terms of efficacy to the innovator product. Two of the biosimilars (CT-P6 from Celltrion and PF-05280014 from Pfizer) demonstrated efficacy equivalence in breast cancer in both the early-stage and metastatic settings.

“Although the FDA and European Medicines Agency determine biosimilarity based on totality of evidence, both the EBC and MBC settings appear to have similar sensitivity and be appropriate for determination of equivalent efficacy based on regulatory guidelines and clinical results,” the researchers wrote in the abstract. “Together, these data support extrapolation between settings.”

Disclosure: The study presented in this abstract was funded by Mylan. For a full list of disclosures, please refer to the original study.

Read more of Cancer Therapy Advisor‘s coverage of the ESMO 2018 meeting by visiting the conference page.


  1. Rugo HS. Settings-based efficacy comparison of trastuzumab biosimilars in breast cancer: A systematic literature review. Abstract presented at: the ESMO 2018 Congress; Munich, Germany: October 22, 2018. Abstract 324P.