Treating HER2+ Metastatic Breast Cancer

Transcript:Adam M. Brufsky, MD, PhD: One last thing I want to talk about that you touched on, before we go on to our final topic. You mentioned a little bit about pertuzumab combinations in APHINITY. But there was, at the San Antonio Breast Cancer Symposium this year, the PERTAIN study. You want to describe PERTAIN to us? You familiar?

Kimberly L. Blackwell, MD: So, basically, these are patients that got the standard chemotherapy/pertuzumab/trastuzumab and then were randomized to adding the aromatase inhibitor (AI) on top of the backbone versus not, if it’s the study.

Adam M. Brufsky, MD, PhD: No. It was triple-positive getting chemotherapy plus trastuzumab and then AI randomized to pertuzumab/trastuzumab.

Kimberly L. Blackwell, MD: What’s not terribly surprising is that, in CLEOPATRA, no one got an aromatase inhibitor after they finished the chemotherapy backbone of the first-line setting. And this is asking the question, does adding an AI in ER-positive after you’ve done that, what I call the “induction CLEOPATRA phase,” help? It did, but that has been our prize for a while, so I guess I’m not particularly surprised by the results. And it didn’t change my practice for ER-positive, HER2-positive breast cancer in the metastatic setting. It just makes sense, and now we have data to support that. When you’re done with the chemotherapy component, which is usually a taxane, remember to start the aromatase inhibitor. I will tell you, I’ve seen a couple of patients as a second opinion, because there’s always this nerve-wracking moment where the chemotherapy is done and they ask, “What else? I’m just doing the 2 antibodies. What else should I be doing right now?” With the aromatase inhibitor, we kind of forget about that, and this study would really argue that we should be adding it when we drop the chemotherapy out.

Adam M. Brufsky, MD, PhD: Mark?

Mark E. Robson, MD: It has been standard practice for us to treat the ER-positive disease. I’m kind of a little surprised about chemotherapy being dropped.

Kimberly L. Blackwell, MD: But it wasn’t allowed in CLEOPATRA, so that’s why this study was important.

Adam M. Brufsky, MD, PhD: Again, it’s really trying to reconcile B-52, where there was no benefit to adding aromatase inhibition, to PERTAIN and other trials like it where there is.

Kimberly L. Blackwell, MD: Don’t make that mistake. That’s an early stage study versus metastatic.

Adam M. Brufsky, MD, PhD: I know. It’s wrong to compare. I get it. I understand.

Mark E. Robson, MD: It was pCR versus survival.

Adam M. Brufsky, MD, PhD: Yes, pCR versus response, I agree.

Aditya Bardia, MD, MPH: But in terms of tumor biology, I think there’s one difference. In B-52, the endocrine therapy was combined with chemotherapy. But here in PERTAIN, we are adding the AI only to the antibodies after the chemotherapy is completed. So, there might be something about combining chemotherapy with endocrine therapy versus combining endocrine therapy with anti-HER2 therapy.

Kimberly L. Blackwell, MD: Good point.

Transcript Edited for Clarity