Breast Cancer: Genomic Testing for Adjuvant Therapy

Transcript:Adam M. Brufsky, MD, PhD: Hello, and thank you for joining this OncLive Peer Exchange® titled, “Advanced Breast Cancer: A Continuum of Care.” As breast cancer research continues to produce positive gains, patients are achieving longer survival through multiple lines of therapy. With this continued progress comes increased complexity in terms of how we choose a course of therapy for the individual patient and how we combine or sequence agents through the continuum of care. In this OncLive Peer Exchange®, my colleagues and I will review the data from the 2016 San Antonio Breast Cancer Symposium. We’ll add a practical perspective on how the new data apply to what we already know about patient care.

I am Dr. Adam Brufsky, and I am a professor of medicine and associate division chief for the Division of Hematology/Oncology at the University of Pittsburgh School of Medicine. Participating today on our distinguished panel are: Dr. Aditya Bardia, attending physician at the Massachusetts General Hospital Cancer Center and assistant professor at the Harvard Medical School in Boston; Dr. Kimberly Blackwell, professor of medicine, assistant professor in radiation oncology and member of the Duke Cancer Institute in Durham, North Carolina; finally, Dr. Mark Robson, attending physician at the Memorial Sloan Kettering Cancer Center in New York, New York. Thank you so much for joining us, and let’s begin.

The first thing to really talk about, even though this is advanced breast cancer, is something that I think is on the minds of a lot of breast cancer oncologists and a lot of general oncologists who also take care of breast cancer. And that is, how do we use all these multiparametric genomics? We have the 21-gene assay, we’ve got the 70-gene assay (MammaPrint), we have the PAM50 assay, we have bioTheranostics (breast cancer index), and we now have EPclin, or EndoPredict. How is someone going to choose, if at all? I’ll start with Mark, who is an attending physician at a major United States cancer center. What do you guys do at Memorial Sloan Kettering Cancer Center?

Mark E. Robson, MD: I think, like many people, we have been using the 21-gene recurrence score for quite some time. And, as a matter of fact, our workflows are set up so that the surgeons are essentially requesting that on everybody who looks like it’s appropriate at the time of the surgery. So, it comes to us as part of our initial oncology consultation. We’ve developed all of our workflows and clinical pathways around that information, but recognizing that it sometimes doesn’t give us the information that we need. And I think most of what we’ve been focusing on is the prediction of chemotherapy benefit. Prognostication is certainly useful, but ultimately, when it comes down to conversations with the patients, you want to know, are they or are they not going to benefit from incremental therapy? Until we have the results of the TAILORx and RxPONDER trials, we’re left in a little bit of a void there.

And so, the MINDACT data are interesting because not only do they give you another prognostic perspective, if you will, the thought that they could at least also contribute to some information about the potential benefit of chemotherapy is attractive. But whether it’s attractive enough, I think that is an uncertain question because of what we were talking about before we began—with the issue of the statistical design of the study and sense of how much benefit from chemotherapy is enough to offer it to people. So, we’re still negotiating through that value proposition.

Adam M. Brufsky, MD, PhD: So, Aditya, what do you use at Massachusetts General Hospital Cancer Center?

Aditya Bardia, MD, MPH: I think our preference is also to use the 21-gene assay, the Oncotype DX, to make a decision about endocrine therapy versus chemotherapy. An issue that we often run into is when we get the intermediate recurrence score. And in that perspective, MammaPrint is different. You either get a positive or negative or a low or high risk. But some would question that it probably also has a gray zone. In terms of preference of using Oncotype versus MammaPrint in general, our preference is to use Oncotype, and I think that that reflects the general practice of the United States also.

Adam M. Brufsky, MD, PhD: Kim?

Kimberly L. Blackwell, MD: I don’t have much to add other than I think in 2017, women facing breast cancer probably should be having their tumor sent for some sort of genomic predictor. And as an oncologist taking care of those women, you should pick one that you know the ins and outs of and be able to communicate what it means very well, whatever that assay is. I don’t think we have a winning assay at this point. I think the most important thing is for the practicing oncologist to really figure out how these assays work, pick one, and make certain that women facing breast cancer are somewhat entitled to those results in their decision making about whether or not to receive chemotherapy or not. And likewise with extended therapy, I’m finding that we have a lot of patients—the longer you’re in practice, you have a lot of patients, and we’re going to talk about it—that reach that 5-year point and ask, “Do I need to stay on it, do I not?” and using these genomic predictors to also guide extended adjuvant endocrine therapy.

Adam M. Brufsky, MD, PhD: I’ll give my impression, too.

Kimberly L. Blackwell, MD: What do you think?

Adam M. Brufsky, MD, PhD: I’ve been very, very vocal on this topic for many years. I think the real issue here is that one thing, Kim, that you pointed out is very, very true. And we’re part of Via Oncology, which is a pathway group that is similar to NCCN, but we’re a little bit more narrow in what we recommend. And we literally just decided, probably 2 months ago, to allow 1 of 3 multiparametric genomic tests. We allow the 21-gene assay, which we all knew about for many years. In fact, that was the one we used for many years. We now are allowing the 70-gene assay, or the MammaPrint, and PAM50. And the one thing you realize when you do these is they all are going to be predictive. Well, they’re always prognostic.

PAM50 does not have predictive data at all, MammaPrint does, and we probably should talk about that a little bit and discuss the design of MINDACT for our audience. The 21-gene Oncotype does have predictive data, too, and we’re all used to Oncotype because it has been around since 2005. We’re used to using it. The initial trials were small, but there have been many, many follow-up registry data from Kaiser. The real interesting thing is they all do the same thing, but there are subtleties between the different tests. And the interesting thing is our major payers, in the western Pennsylvania area, really have gone into the weeds and they actually look at the characteristics of the patient before they allow someone to have the test. For example, if you’re postmenopausal or you’re premenopausal, you cannot have PAM50. If you have 1 to 3 nodes positive, you can’t have an Oncotype DX.

We now actually have payers that are coming to us and they’re saying, “Well, listen, we’re going to give you 1 test.” And they only give you 1 test. You can’t do 2. So, we’re really getting into it, and I don’t know if there’s going to be sophistication—there probably should—maybe around the country. But I think this is where we’re possibly going because these tests are not cheap and some of the payers are really starting to look at them and ask what they’re really doing.

Transcript Edited for Clarity