Adding ribociclib to endocrine therapy improved invasive and distant disease-free survival of patients with early-stage HR-positive/HER2-negative breast cancer.
Most breast cancers are diagnosed at an early stage. The current standard of care for patients with early-stage HR-positive/HER2-negative breast cancer is surgery with or without radiotherapy followed by 5 or 10 years of adjuvant endocrine therapy. However, up to one-third of patients with stage II and more than half of patients with stage III HR-positive/HER2-negative early breast cancer will experience disease recurrence.
In patients with advanced HR-positive/HER2-negative breast cancer, the addition of a CDK4/6 inhibitor to endocrine therapy increases disease-free and overall survival, maintaining QOL. The phase 3 NATALEE trial (NCT03701334) evaluated the addition of the CDK4/6 inhibitor ribociclib to endocrine therapy in patients with early-stage HR-positive/HER2-negative breast cancer. Dennis Slamon, MD, presented the primary results at the 2023 ASCO Annual Meeting, held June 2-6 in Chicago.
In NATALEE, 5,101 participants with early-stage HR-positive/HER2-negative breast cancer were randomly assigned 1:1 to either adjuvant treatment with ribociclib (400 mg/day for 3 years) plus endocrine therapy (for at least 5 years) or treatment with endocrine therapy alone. As of the data cut-off, the median follow-up was 34 months.
The addition of ribociclib to adjuvant endocrine therapy significantly improved the 3-year invasive disease-free survival (iDFS) rate: 90.4% versus 87.1% (HR, 0.748; P=0.0014). The absolute iDFS benefit at 3 years follow-up was 3.3%. The risk for invasive disease was reduced by 25.2%. iDSP benefit was consistent across all prespecified subgroups. In addition, the 3-year distant disease-free survival rate was significantly improved in patients treated with ribociclib: 90.8% versus 88.6% (HR, 0.739; P=0.0017). The risk for distant disease (metastasis) was reduced by 26.1%. The overall survival data are not yet mature.
Dr. Slamon concluded that “NATALEE results support ribociclib plus endocrine therapy as a new treatment of choice in a broad population of patients with HR-positive/HER2-negative early breast cancer.”
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