Neoadjuvant Ontruzant (SB3) in Patients With HER2-positive Early Breast Cancer: An Open-Label (NeoON)

The treatment of patients with HER2 positive early breast cancer has continuously improved over the last decades. Up to now both, trastuzumab and pertuzumab are approved in combination with chemotherapy (CTX) not only for the adjuvant but also for the neoadjuvant treatment of early breast cancer patients. A high pCR rate in the neoadjuvant setting was shown in several trials and observational studies with CTX+ trastuzumab and with CTX+ pertuzumab. The efficacy is dependent on a variety of mechanisms including the blocking of the important PI3K/Akt and MAPK pathways, and ADCC (antibody dependent cellular toxicity). Recently the biosimilar Ontruzant® (SB3) has been introduced into the treatment of HER2 positive breast cancer as a biosimilar. Efficacy and toxicity have been shown to be equivalent to the first approved antibody, however, data from the real-world setting have not been published like it has for the originally approved antibody. Therefore, the aim of this study is to establish safety and efficacy for Ontruzant® in the real world setting. Patients can be included if they are treated with Ontruzant® in the neoadjuvant setting. Additionally, the study will be accompanied by a comprehensive immune monitoring program and biomarker program to explore immune oncology potential for the neoadjuvant treatment.