Dr. Kalinsky on Initial Results of the RxPONDER Trial in HR+/HER2- Breast Cancer

Kevin Kalinsky, MD, MS, director of the Glenn Family Breast Center and Breast Medical Oncology at Winship Cancer Institute, and acting associate professor in the Department of Hematology and Medical Oncology at Emory University School of Medicine, discusses the initial results of the phase 3 RxPONDER trial in patients with hormone receptor (HR)–positive, HER2-negative breast cancer.

Findings from a prespecified interim analysis of the RxPONDER trial, which were presented virtually during the 2020 San Antonio Breast Cancer Symposium, revealed an improvement in invasive disease-free survival (iDFS) with the addition of chemotherapy to standard endocrine therapy in premenopausal patients with HR-positive, HER2-negative, lymph node–positive breast cancer and recurrence scores between 0 and 25. Notably, the iDFS benefit was not observed in postmenopausal patients, who did not appear to derive any significant benefit from the addition of chemotherapy, Kalinsky says.

In premenopausal patients, the 5-year iDFS rate was 94.2% in the chemotherapy/endocrine therapy arm compared with 89% in the endocrine-alone arm. Conversely, in postmenopausal patients, the 5-year iDFS rate was 91.6% and 91.9%, respectively.

These findings, as well as a trend toward improved overall survival among premenopausal patients who received chemotherapy plus endocrine therapy, signaled the need to release these interim data, concludes Kalinsky.