Results from a phase 3 study evaluating the efficacy and safety of biosimilar ABP 980 compared with trastuzumab in patients with human epidermal growth factor receptor 2 (HER2)-positive early breast cancer have ruled out inferiority compared to trastuzumab but could not rule out superiority based on its primary efficacy endpoint: the difference of the percentage of patients with a pathological complete response (pCR). The primary endpoint had a prespecified equivalence margin of ±13%, and the observed upper end of the confidence interval was 13.4%.
Overall, adverse events were comparable between ABP 980 and trastuzumab. In the neoadjuvant phase of the study, which included chemotherapy, there were more serious adverse events reported in the ABP 980 group, the majority of which were reported by the investigators as unlikely to be related to the investigational product. In the adjuvant phase of the study, which did not include chemotherapy, serious adverse events were comparable between treatment groups. The overall results also showed comparable immunogenicity.
"We believe this study confirms no clinically meaningful differences between ABP 980 and trastuzumab, and we look forward to continued discussions with regulatory authorities," said Sean E. Harper, MD, Executive Vice President of Research and Development at Amgen. "Biosimilars are approved based on the analytical, nonclinical, and clinical data, and we believe that the totality of the evidence we've generated supports ABP 980 as highly similar to the reference product."
ABP 980 is being developed as a biosimilar to trastuzumab, a recombinant DNA-derived humanized monoclonal immunoglobulin G1 kappa antibody that targets HER2. Trastuzumab is approved in many regions for the treatment of HER2-positive early breast cancer, metastatic breast cancer, and metastatic gastric cancer.
Amgen and Allergan are collaborating on the development and commercialization of four oncology biosimilars. Amgen has a total of nine biosimilars in development. Allergan is also independently developing biosimilars.
Source: Amgen; July 21, 2016.