New drug (name: ARV-471) for the neoadjuvant treatment of hormone receptor-positive breast cancer

Breast cancer (mammary carcinoma) is a malignant disease of the mammary gland tissue characterized by the uncontrolled proliferation of mammary gland cells. Treatment of the disease depends on numerous factors, such as the patient’s overall health, the tumor’s growth rate (Ki-67 index), detectable hormone receptors on the surface of the cancer cells (estrogen receptor-positive, progesterone receptor-positive), and the increased expression of the HER2 protein on the cells (HER2-positive). The stage of the disease is also very important; while in the locally confined stage (stages 1–2A) the disease is limited to the breast and a cure is highly likely, the locally advanced stage (stages 2B–3B) that the tumor is already larger or that lymph nodes are involved. Locally confined breast cancer is usually removed surgically. Prior to surgery, hormone receptor-positive breast cancer can be treated with hormone therapy (neoadjuvant therapy), which is intended to reduce the tumor’s size and improve the surgical outcome. Hormone therapy involves the use of aromatase inhibitors, such as the already approved drug anastrozole. These are intended to slow down the production of estrogen, which is supposed to inhibit the estrogen-dependent growth of tumor cells. The new, as-yet-unapproved drug ARV-471 represents a novel therapeutic approach in this context. The drug acts directly on the estrogen receptor of the cancer cells and destroys it. As a result, hormones can no longer bind to the tumor cells and stimulate their growth.

The goal of this Phase 2 study is to further investigate the efficacy and safety of ARV-471 compared to anastrozole prior to surgical removal of the tumor in a selected group of patients. Participants will be randomly assigned to one of two groups as part of the study. Group 1 will receive ARV-471 once daily as a tablet until surgery, which usually takes place after approximately 5.5 months. Group 2 will receive anastrozole, also once daily as a tablet, until surgery. The study is open-label, meaning that both the medical staff and the patients know which medications are being taken. Efficacy is assessed after 2 weeks; treatments and follow-up examinations as part of the study continue for up to 6 months, during which the efficacy of the hormone therapies is evaluated.

Postmenopausal women aged 18 and older with hormone receptor-positive, HER2-negative breast cancer are eligible to participate in this study. The breast cancer must be locally confined, with no lymph node involvement and no metastases.