Breast Cancer Coverage from Every Angle

Advanced Breast Cancer: Overall Survival Subgroup Analysis From MONALEESA-2 Trial

By: Vanessa A. Carter, BS
Posted: Thursday, January 6, 2022

The MONALEESA-2 study evaluated first-line ribociclib plus letrozole versus letrozole alone in patients with hormone receptor–positive, HER2-negative, advanced breast cancer. Previous findings of this phase III trial have demonstrated an improvement in overall survival among premenopausal women. The results of the overall survival subgroup analysis, conducted by Joyce O’Shaughnessy, MD, of Texas Oncology-Baylor University Medical Center, Dallas, and colleagues, were presented during the 2021 San Antonio Breast Cancer Symposium (SABCS; Abstract GS2-01).

“Consistent with the intent-to-treat population of MONALEESA-2, the results of this prespecified exploratory analysis demonstrated an overall survival benefit with ribociclib plus letrozole independent of the site and number of metastatic lesions,” the investigators concluded.

This exploratory analysis focused on 668 patients with hormone receptor–positive, HER2-negative, advanced breast cancer who were premenopausal. Participants were randomly assigned to receive first-line letrozole plus ribociclib or placebo. Subgroups were determined by baseline location (bone alone, liver involvement, liver or lung involvement) and number of metastatic sites (< 3 or ≥ 3).

Regardless of the baseline metastatic site, all subgroups demonstrated a consistent overall survival improvement with ribociclib plus letrozole versus letrozole alone. Notably, patients who generally have a worse prognosis, such as those with liver metastases (hazard ratio [HR] = 0.81), liver or lung metastasis (HR = 0.81), or three or more metastatic sites (HR = 0.71), experienced a benefit in overall survival on combination treatment; those with bone-alone metastasis also had a survival improvement (HR = 0.78).

Disclosure: For full disclosures of the study authors, visit

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