Observational Study on the Efficacy, Tolerability, and Side Effects of Treatment with Ribociclib (Approved Drug)

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 stage (extent) 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 expression of the HER2 protein on the cells (HER2-positive). In a locally advanced stage (Stage 2B to 3) or when breast cancer has already spread to other parts of the body (metastases, Stage 4), the disease is often no longer curable. In such cases, the goal is to “keep the disease at bay” for as long as possible. If the cancer cells are hormone receptor-positive, anti-hormone therapy is the standard of care. Typically, tamoxifen is used before menopause, and an aromatase inhibitor is used after menopause, either as monotherapy or in combination with other treatments. Ribociclib is a so-called CDK4/6 inhibitor that, by binding to cancer cells, can halt their growth and further enhance the effectiveness of anti-hormone therapy. The drug is already approved in combination with anti-hormonal therapy as the treatment of choice for advanced or metastatic, hormone receptor-positive, and HER2-negative breast cancer.

The goal of this single-arm Phase 4 study is to further investigate the effectiveness of the combination of ribociclib and anti-hormone therapy in a large number of patients. The anti-hormone therapy drug will be selected by the treating physicians and administered in combination with ribociclib. All study participants receive 600 mg of ribociclib from Day 1 to Day 21 as part of a 28-day cycle, followed by a seven-day break. The study is open-label, meaning that both the medical staff and the study participants know which medications are being taken. No new medications or treatment modalities are being tested. The primary focus is on evaluating how the disease has progressed after one year of treatment; biomarkers are also being examined. The primary endpoints of the study are overall survival and progression-free survival. Follow-up visits will be conducted as part of the study for up to three years to assess the efficacy of the therapy and the occurrence of side effects from ribociclib.

Women aged 18 and older with locally advanced or metastatic, hormone receptor-positive, and HER2-negative breast cancer are eligible to participate in this study.