Phase 3 RxPONDER Trial Brings Good News for Women with Common Breast Cancer Type

Kevin Kalinsky, MD, MS, study author of the Phase 3 RxPONDER study and director of the Glenn Family Breast Center at Winship Cancer Institute of Emory University, presented the initial results of the phase 3 RxPONDER trial at the San Antonio Breast Cancer Symposium. The study is one of the biggest randomized, prospective clinical trials assessing women node-positive, hormone receptor positive (HR+), HER2- early breast cancer. Dr Kalinsky discussed the preliminary results in an interview with DocWire News.

DocWire News: What prompted you to undertake this study?

Dr. Kalinsky: Ensuring that breast cancer patients get the right treatment for their disease—not too much, not too little—is increasingly important in this era of personalized medicine. We had evidence from an earlier SWOG Cancer Research Network clinical trial, S8814, that suggested that Recurrence Score results from patients with lymph node-positive breast cancer that is HR-positive and HER2 negative could potentially predict chemotherapy benefit for patients. We designed this trial, RxPONDER, to find out and launched it in 2011. Our original question gained even more urgency in 2018, when results from the landmark TAILORx trial showed that Recurrences Score results can predict chemotherapy benefit for patients with this type of breast cancer—when it had not already spread to the lymph nodes. Would it also predict benefit for women whose cancer had spread to their lymph nodes? Our final data will tell.

DocWire News: What are the key takeaways from the study?

Dr. Kalinsky: There are two key takeaways. For postmenopausal women with this type of breast cancer, our findings mean they are spared the time, money, and harmful side effects that come with chemotherapy. For premenopausal women, our findings mean they can be assured that chemotherapy should, in fact, help them live longer or without their disease spreading. Either way, our results are great news for women diagnosed with this common type of breast cancer. We’re moving away from a one-size-fits-all treatment approach.

DocWire News: Did any of the study’s findings surprise you?

Dr. Kalinsky: The early nature of the data release surprised me. That we could see such a clear trend in the data, while only about halfway into our monitoring period, was a surprise for all of us involved.

DocWire News: What limitations did the study have?

Dr. Kalinsky: A key limitation is, of course, that results are preliminary. We will follow patients on RxPONDER for a total of 15 years, so we have a lot more time before the study data is fully mature and we can draw final conclusions on the findings.

DocWire News: Do you have any future research plans pertaining to this area?

Dr. Kalinsky: There is the final result to analyze and share, and we expect a lot more publications and presentations out of RxPONDER.

DocWire News: Any information not addressed by the previous questions that you would like to share?

Dr. Kalinsky: The study team and I believe that these findings, even though they’re preliminary, will quickly change medical practice. They are likely to have an immediate impact on patients and the doctors who treat them, all around the world. Also, the study results provide yet more evidence that breast cancer treatment—indeed all cancer treatment—can be increasingly personalized. Results also provide more proof that genomic and genetic data are key to this personalization. Knowing what is happening inside a tumor is becoming as important as knowing how big a tumor is and where it is found in the body. Genomic and genetic tests can be important to cancer patient care.