Ribociclib + Endocrine Therapy for Breast Cancer

(NATALEE Trial)

This trial tests the effectiveness and safety of ribociclib (Kisqali) combined with endocrine therapy for treating early-stage, hormone receptor-positive (HR+) and HER2-negative breast cancer. Participants will receive either ribociclib with endocrine therapy or endocrine therapy alone. Ideal candidates have undergone surgery to remove breast cancer, show no signs of cancer spreading, and have hormone receptor-positive, HER2-negative breast cancer. As a Phase 3 trial, it represents the final step before FDA approval, providing participants an opportunity to contribute to potentially groundbreaking treatment advancements.

The trial requires that you stop taking certain medications, especially those that strongly affect liver enzymes (CYP3A4/5) or have a narrow safety margin. If you're on hormone replacement therapy or certain cancer prevention drugs, you may need to stop those as well.

Research has shown that ribociclib, when combined with hormone therapy, is generally well-tolerated by patients with HR+/HER2- early breast cancer. Most side effects from ribociclib can be managed by adjusting the dose, allowing many patients to continue treatment. This suggests it is relatively safe for use.

Hormone therapy alone has long been a standard treatment for hormone receptor-positive breast cancer, indicating its safety for treating this type of cancer.

Ribociclib combined with endocrine therapy is unique because it targets the growth of cancer cells in a new way. Unlike standard treatments for breast cancer, which often rely solely on endocrine therapy to block hormones that fuel cancer growth, ribociclib is a CDK4/6 inhibitor. This means it specifically interrupts the cycle that cancer cells use to divide and multiply. Researchers are excited about this combination because it has the potential to enhance the effectiveness of endocrine therapy, offering a more powerful option for slowing the progression of the disease.

Research has shown that combining ribociclib with hormone therapy, which participants in this trial may receive, greatly improves outcomes for patients with HR+/HER2- early breast cancer. Studies have found that this combination helps patients live longer without cancer recurrence for at least five years. It also significantly delays cancer progression compared to other treatments. Overall, ribociclib plus hormone therapy appears to provide better long-term outcomes for patients with this type of breast cancer. Another group in this trial will receive endocrine therapy alone, serving as an active comparator.²⁴⁶⁷⁸