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

Kevin Kalinsky, MD, MS, director of the Glenn Family Breast Center and Breast Medical Oncology and Louisa and Rand Glenn Family Chair in Breast Cancer Research at Winship Cancer Institute, associate professor in the Department of Hematology and Medical Oncology at Emory University School of Medicine, discusses updated results from the phase 3 RxPONDER trial (NCT01272037) in patients with hormone receptor (HR)-positive, HER2-negative breast cancer.

The RxPONDER trial randomized 5015 patients with HR-positive, HER2-negative breast cancer with a recurrence score between 0 and 25 without distant metastases to endocrine therapy alone or chemotherapy followed by endocrine therapy. The initial results showed that the 5-year invasive disease-free survival (iDFS) rate was 94.2% with chemotherapy/endocrine therapy vs 89.0% with endocrine therapy alone. In postmenopausal patients, the 5-year iDFS rates were 91.6% and 91.9%, respectively. This suggested that postmenopausal women with 1 to 3 positive nodes and a recurrence score between 0 and 25 are likely able to forgo adjuvant chemotherapy without compromising iDFS.

During the 2021 San Antonio Breast Cancer Symposium, updated findings with 6 years of follow-up from RxPONDER were presented, further validating the initial findings. Postmenopausal women did not benefit in terms of iDFS, distant recurrence-free survival, or distant recurrence-free interval with the addition of chemotherapy to endocrine therapy. However, premenopausal women did derive benefit from chemotherapy/endocrine therapy in terms of these end points.

Ultimately, these findings support the shift away from one-size-fits-all treatment approaches for patients with HR-positive, HER2-negative breast cancer. Moreover, the results support the use of oncotyping to inform chemotherapeutic treatment decisions in this patient population, Kalinsky concludes.