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William J. Gradishar, MD, FACP, FASCO
William J. Gradishar, MD, FACP, FASCO
Posted: Friday, December 9, 2022
Adding the mTOR inhibitor everolimus to standard adjuvant endocrine therapy did not seem to improve invasive disease–free or overall survival in patients with high-risk hormone receptor–positive, HER2-negative breast cancer, according to Marianna Chavez MacGregor, MD, MSc, FASCO, of The University of Texas MD Anderson Cancer Center, Houston, and colleagues. The results of the phase III SWOG S1207 trial, which were presented during the 2022 San Antonio Breast Cancer Symposium (SABCS; Abstract GS1-07), also revealed a low completion rate and an increased incidence of adverse events with this combination.
A total of 1,792 eligible patients were randomly assigned in a 1:1 ratio to receive physicians’ choice of adjuvant endocrine therapy plus up to 1 year of treatment with everolimus or a placebo. With a median follow-up of 50.5 months, there were 389 invasive disease–free survival events. The 5-year invasive disease–free survival rate was 74.8% with everolimus and 73.9% with the placebo (hazard ratio [HR] = 0.93); however, the investigators noted the proportional hazards assumption was violated (P = .02), suggesting a differential treatment effect over time. The hazard ratios were 0.72 and 1.00 during and after the 1 year of treatment, respectively. The 5-year overall survival rate was 87.6% with everolimus and 85.5% with the placebo (HR = 0.98).
The benefit of treatment with everolimus did not appear to increase with risk. Invasive disease–free (HR = 1.08) and overall (HR = 1.19) survival outcomes did not seem to differ among postmenopausal patients. Among premenopausal patients, everolimus was found to be associated with improved invasive disease–free (HR = 0.63) and overall (HR = 0.48) survival outcomes.
The treatment completion rate was lower with everolimus than with the placebo (47.9% vs. 72.7%). Grade 3 (31.2% vs. 6.5%) and 4 (3.7% vs. 0.5%) toxicities were reported more frequently with everolimus than with the placebo.
Disclosure: For full disclosures of the study authors, visit sabcs.org.
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