Observational Study on the Combination Therapy of Abemaciclib and Anti-Hormone Therapy in Metastatic Breast Cancer

Breast cancer (mammary carcinoma) is a malignant disease of the breast gland tissue characterized by the uncontrolled proliferation of breast gland cells. In its early stages, the disease is confined to the breast. As the disease progresses, it often spreads to the lymph nodes and forms secondary tumors (metastases) in other parts of the body (bones/organs). This is referred to as metastatic disease, which corresponds to stage 4.

Treatment of the disease depends on numerous factors, such as the patient’s overall health, the stage of the disease, the tumor’s growth rate (Ki-67 index), the presence of detectable hormone receptors on the surface of the cancer cells (estrogen receptor-positive, progesterone receptor-positive), and the increased presence of HER2 receptors on the cells (HER2-positive). Cancer cells often have hormone receptors, making anti-hormone therapy a core component of treatment. Since the effectiveness of anti-hormone therapy can diminish over the course of the disease due to changes in the tumor cells (development of resistance), anti-hormone therapy is now frequently combined directly with a CDK4/6 inhibitor. This is a relatively new class of drugs that can further slow the growth of malignant cells. Abemaciclib has already been approved for this purpose and has proven to be very effective in studies.

The goal of this observational study is to collect additional treatment data on anti-hormone therapy in combination with abemaciclib. The course of the disease will be monitored for a maximum of 4 years after the start of therapy. No additional medication will be tested in this study, nor will any new therapy be administered. During the study, tumor cells and tumor DNA in the blood will be analyzed using a technique known as liquid biopsy to assess the response rate to therapy.

Patients aged 18 and older with metastatic breast cancer may participate in this study if they have symptoms of organ metastasis and a combination of anti-hormone therapy with abemaciclib is planned as the first treatment following metastasis (first-line therapy). The disease must be hormone receptor-positive and HER2-negative.