Comparison of Treatment Approaches: Anti-hormonal therapy with ribociclib (a new drug that inhibits cell growth) versus standard chemotherapy in patients with moderate risk of recurrence

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). Treatment for breast cancer at a locally confined stage with no evidence of metastases typically involves breast-conserving surgery preceded by chemotherapy (neoadjuvant) with the goal of complete recovery. To reduce the risk of the disease returning, radiation therapy and drug therapy (adjuvant) may be administered after surgery. The more risk factors there are for a recurrence of the disease, the more important this treatment becomes. If the cancer cells have hormone receptors on their surface, anti-hormone therapy may be administered. Since the effectiveness of anti-hormone therapy may 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. Ribociclib has already been approved for this purpose and has proven to be very effective in studies. Alternatively, conventional chemotherapy can be used, which has also been shown to be effective. Various medications and treatment regimens are available for this purpose.

The goal of this Phase 3 study is to compare both treatment approaches, both in the initial phase of treatment (neoadjuvant) and following initial treatment (adjuvant). Participants will be randomly assigned to 2 groups as part of the study. Group 1 (study arm) will receive antihormonal therapy (the exact regimen will be selected by the treating physician according to current standards) plus ribociclib 200 mg three times daily in tablet form over 26 cycles. Group 2 (control arm) will receive 16- to 24-week standard chemotherapy. The study is open-label, meaning that both medical staff and patients know which medications are being administered. Treatments and follow-up examinations as part of the study will continue for up to 5 years, during which the effectiveness of the therapy and the occurrence of side effects from the various medications will be evaluated. The key factor is whether or when the disease recurs during treatment.

Patients aged 18 and older, whether premenopausal or postmenopausal, with hormone receptor-positive, locally confined breast cancer (without metastases) are eligible to participate in this study. The disease must be classified as intermediate-risk.