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William J. Gradishar, MD, FACP, FASCO
William J. Gradishar, MD, FACP, FASCO
Posted: Wednesday, January 24, 2024
Presented at the 2023 San Antonio Breast Cancer Symposium (Abstract GS01-12), the final overall survival results from the phase III MONARCH 3 study showed an overall survival of more than 5.5 years among postmenopausal patients with hormone receptor–positive, HER2-negative advanced or metastatic breast cancer taking the CDK4/6 inhibitor abemaciclib in combination with an aromatase inhibitor. Stephen R.D. Johnston, MD, PhD, of The Royal Marsden NHS Foundation Trust, London, and colleagues noted this was an increase of 13.1 months compared with the intent-to-treat population (66.8 vs 53.7 months), although statistical significance for the overall survival outcome was not reached (hazard ratio [HR] = 0.804; 95% confidence interval [CI] = 0.637–1.015; P = .0664).
“At 8 years of follow-up, when the natural history of metastatic breast cancer starts to substantially impact patient survival, it is highly encouraging to see abemaciclib combined with aromatase inhibitor therapy deliver a meaningful survival difference…in women at even higher risk due to visceral disease,” said Dr. Johnston. “Despite missing statistical significance, these data are clinically relevant and highly consistent with the overall body of evidence for abemaciclib in advanced or metastatic breast cancer.”
A total of 493 postmenopausal women with hormone receptor–positive, HER2-negative advanced or metastatic breast cancer were included in the randomized, double-blind study. In addition to the previously mentioned outcomes, the final survival data showed a median overall survival of more than 5 years among patients with visceral organ metastases, with an increase in median overall survival of 14.9 months among those who received abemaciclib compared with those who did not (63.7 vs 48.8 months). The investigators reported this result included patients whose breast cancer had spread to the liver or lungs, and the overall survival results for this subpopulation were also not statistically significant (HR = 0.758; 95% CI = 0.558–1.030; P = .0757).
Disclosure: For full disclosures of the study authors, visit atgproductions.net.
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