ASCO 2021: MONALEESA-3 Survival Update of Ribociclib/Fulvestrant for Advanced Breast Cancer
Posted: Tuesday, June 29, 2021
After nearly 5 years of follow-up, the CDK4/6 inhibitor ribociclib plus fulvestrant continued to achieve improved overall survival compared with a placebo plus fulvestrant for patients with hormone receptor (HR)-positive, HER2-negative advanced breast cancer, according to an update to the phase III MONALEESA-3 clinical trial. Dennis J. Slamon, MD, PhD, of the University of California Los Angeles, and colleagues presented these findings during the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting (Abstract 1001).
“The overall survival benefit of ribociclib was observed in the first-line and second-line subgroups, which further supports the use of ribociclib in these populations,” the authors wrote.
The trial included 726 postmenopausal patients with HR-positive, HER2-negative advanced breast cancer receiving their first-line or second-line treatment. Patients were randomly assigned 2:1 to receive either ribociclib plus fulvestrant or a placebo plus fulvestrant. At the data cutoff of October 30, 2020, 68 patients were still receiving ribociclib plus fulvestrant, and 21 patients were still receiving a placebo plus fulvestrant.
The median follow-up was 56.3 months. Median overall survival was 53.7 months with ribociclib and 41.5 months with the placebo (hazard ratio = 0.73). In the first-line subgroup, median overall survival was not reached for the ribociclib arm, compared with 51.8 months for the placebo arm. In the second-line subgroup, median overall survival was 39.7 months for the ribociclib arm and 33.7 months for the placebo arm. By data cutoff, more patients in the placebo arm had reached the time to their first chemotherapy event (54%) than in the ribociclib arm (44%).
The authors observed no new safety signals. “The results also demonstrated a significant delay in the use of subsequent chemotherapy with ribociclib versus placebo,” they noted.
Disclosure: The study authors’ disclosures may be found at coi.asco.org.