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Expert Discusses MINDACT, TAILORx Studies in Breast Cancer

Brandon Scalea
Published: Monday, Oct 29, 2018

Dr. Elizabeth A. Mittendorf
Michelle E. Melisko, MD
Although chemotherapy may have a lesser role in breast cancer treatment for select patients, there are still high-risk populations who will derive benefit from this modality, said Michelle E. Melisko, MD.

Updated findings from the MINDACT trial identified a subset of women who could safely avoid not only adjuvant chemotherapy, but also radiotherapy. The data show that patients with small, low-grade, well-defined breast tumors and a genetic profile showing they are at low risk of the cancer metastasizing were unlikely to benefit from adjuvant chemotherapy.

Among 6693 patients enrolled in the study, treatment decisions were made based on the size, grade, and hormonal status of the tumor. Genetic makeup was investigated using MammaPrint, which analyzes 70 genes to determine risk of recurrence.

Furthermore, results from the phase III TAILORx study presented at the 2018 ASCO Annual Meeting paved the way for physicians to reduce the toxicity of treatment for early-stage breast cancer. The trial utilized the Oncotype DX Breast Recurrence Score to determine the efficacy of hormone therapy plus chemotherapy versus hormone therapy alone in intermediate-risk patients.

In patients with hormone receptor (HR)–positive, HER2-negative breast cancer, TAILORx demonstrated noninferiority for endocrine therapy alone. After 5 years of follow-up, invasive disease-free survival (iDFS) rates were 92.8% for those who had hormone therapy alone and 93.1% for those who also had chemotherapy. At 9 years, IDFS rates were 83.3% and 84.3%, respectively.2

In an interview during the 2018 OncLive® State of the Science Summit™ on Breast Cancer, Melisko, a clinical professor of medicine at the University of California, San Francisco, discussed the clinical implications of the TAILORx and MINDACT studies.

OncLive: Please provide an overview of your presentation at the State of the Science Summit.TM

Melisko: I reviewed the clinical trials that have recently been published and presented, including MINDACT for MammaPrint and the TAILORx trial, which looked at the value of the Oncotype DX assay to predict the benefit of chemotherapy in patients with HR-positive, HER2-negative breast cancer. I gave a brief historical reference of how we used to give chemotherapy to almost all patients with estrogen receptor (ER)-positive, HER2-negative breast cancers.

Things have started to evolve over time, beginning with the introduction of Oncotype DX as far back as the early 2000s; MammaPrint came in the mid-2000s. We started to realize that not all patients may benefit equally from chemotherapy. I reviewed the data from these 2 trials and compared and contrasted the populations and differences in endpoints. I wanted to help the community oncologists decide which of these assays is the best to send for each case.

Could you discuss the importance of the TAILORx trial?

I remember the day this trial reported, and it was actually shocking that [subsequently] so many patients were coming in with high-risk disease—triple-negative breast cancer, HER2-positive breast cancers, young women with 6- to 7-cm tumors, and node-positive disease. They were saying things like, “I just read in the paper today that I don’t need chemotherapy.” I said, “We’ve been using Oncotype DX since about 2002, and if I thought that test would provide value for you, we would have ordered it.”

The problem with the [consumer media] is that they tend to sensationalize things, so they made it seem like we simply didn’t have this test in our practice and had no interest in it. The population of patients in TAILORx—the 11 to 25 recurrent score population—has been a challenge for breast oncologists for a long time. The traditional Oncotype DX intermediate score bucket was not aligned with that—it was about 17 to 30.

The TAILORx trial shifted the population down and sort of said, “OK, now we have a whole population that we don’t know what to do with.” Generally, clinical judgement still weighed in. If I had a patient with a 1.1-cm grade 1 cancer, I would seldom send for an Oncotype DX because I knew what the score was going to be. I knew these women would not need chemotherapy. This test is very helpful for patients on the edge with tumors closer to 2 cm that are of intermediate grade. People need to understand that medical oncologists have already implemented this practice of offering less chemotherapy.

View Conference Coverage
Online CME Activities
TitleExpiration DateCME Credits
Community Practice Connections™: How Do We Leverage PARP Inhibition Strategies in the Contemporary Treatment of Breast Cancer?May 31, 20191.5
Community Practice Connections™: A Better Way to Stop Pain: Paths Toward Responsible Postsurgical Pain Management for Patients With Breast CancerMay 31, 20191.5
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