An observational study of the already approved drug Ontruzant (a drug that targets the HER2 receptor) to gather more information on its efficacy and tolerability

Breast cancer (mammary carcinoma) is a malignant disease of the mammary gland tissue characterized by uncontrolled cell proliferation in the mammary gland. Treatment depends on numerous factors, including the patient’s overall health, the stage of the disease, the tumor’s growth rate (Ki-67 index), the presence of hormone receptors on the cell surface (estrogen receptor- or progesterone receptor-positive), and the increased expression of the HER2 receptor (HER2-positive). Treatment for breast cancer at an early, locally confined stage without distant metastases in the body generally involves breast-conserving surgery with the goal of complete recovery. Drug therapy prior to surgery (neoadjuvant) has become the standard of care, as it has a significant impact on the prognosis, in part because it reduces the size of the tumor prior to surgery. In cases of HER2-positive disease, this therapy specifically targets the HER2 receptor on the tumor cells. Standard medications here include trastuzumab, sometimes in combination with pertuzumab. In addition, patients receive chemotherapy.

In the NeoOn study, the already approved drug Ontruzant® is administered. Ontruzant® is a so-called biosimilar of the original drug Herceptin®. Both drugs contain the same active ingredient, trastuzumab, but are manufactured by different companies. The drug is biologically nearly identical to Herceptin®. In the NeoOn study, Ontruzant® is used for six cycles of neoadjuvant therapy in combination with chemotherapy—with or without pertuzumab, depending on the treating physicians’ decision. The goal is to gather further data on the drug’s efficacy and safety. The study is open-label, meaning that both the medical staff and the patient know which medications are being administered.

Women with HER2-positive early-stage breast cancer who have not yet received treatment are eligible to participate in the study. Patients must not be pregnant and must be in good physical condition. There must be an indication for neoadjuvant therapy. In addition, a lesion at least 1 cm in size must have been detected on an MRI or ultrasound.