Breast Cancer Coverage from Every Angle

Comparing Trastuzumab Biosimilar and Reference Trastuzumab in HER2-Positive Breast Cancer

By: Hillary Ojeda
Posted: Wednesday, August 29, 2018

Recent findings in The Lancet Oncology reported similar efficacy and safety outcomes for women with HER2-positive early breast cancer who were treated with the trastuzumab biosimilar ABP 980 compared with reference trastuzumab. However, Professor Gunter von Minckwitz, MD, of the German Breast Group, Neu-Isenburg, Germany, and colleagues, also found the upper bounds of the 90% confidence intervals for risk ratio and risk difference “exceeded the predefined equivalence margins when based on local laboratory review of tumour samples, meaning that nonsuperiority was nonconclusive.”

“To our knowledge, this is the first study of a trastuzumab biosimilar encompassing a single-switch design from the reference product to a biosimilar, which allowed us to assess the clinical safety and immunogenicity of this approach to treatment,” the investigators concluded.

This randomized, double-blind, phase III LILAC trial included 725 patients from 97 centers in 20 countries, primarily in Europe and South America, who had histologically confirmed HER2-positive invasive early breast cancer. Neoadjuvant treatment was followed by surgery 3 to 7 weeks later, and then patients received adjuvant treatment with ABP 980 or reference trastuzumab. Of the nearly 700 patients assessed for the primary endpoint (choice of locally reviewed pathologic complete response), 358 received ABP 980 and 338 received reference trastuzumab.

Pathologic complete response was reported in 48% of the ABP 980 group compared with 41% of the reference trastuzumab group (risk difference = 7.3%); the upper bounds of the confidence intervals exceeded the predefined equivalence margins of 13% and 1.318 for the endpoints. Pathologic complete response was observed in 48% vs 42% (risk difference = 5.8%), respectively, on central laboratory assessment.

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