Molecular Testing in Breast Cancer

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Transcript:

Benjamin P. Levy, MD: Let’s move on, take a step back, and talk about molecular testing in general. As I mentioned, all of us use different drugs in our disciplines [of] breast, GI [gastrointestinal], and lung. But I think, again, strategically and thematically, we’re beginning to approach cancer in a way that’s predicated on biomarkers, and predicated on a better understanding of what’s going on at the molecular level of the tumor. So I’ll start with breast here and maybe Kevin and Kayla can walk us through what testing looks like for breast cancer at Emory [Winship Cancer Institute of Emory University in Atlanta, Georgia] and maybe what are best practices. Maybe, Kayla, I can start with you on that, how do you talk to patients and what does this journey look like when testing patients?

Kayla Freeman, DNP, APRN, FNP-C: For biomarker testing for our patients, typically it’s occurring with their initial biopsy. When I think about the metastatic setting, of course, we can repeat these if we think receptors have changed, but typically it’s ordered with the initial biopsy.

Benjamin P. Levy, MD: How are you approaching that patient when they come in?

Kayla Freeman, DNP, APRN, FNP-C: When I see a patient typically to discuss what it looks like in their biomarkers, I like to print out their pathology and go over what their biomarkers are, whether it be ER/PR+ [estrogen receptor/progesterone receptor positive] or HER2+ [human epidermal growth factor receptor 2 positive] and explaining to the patient what treatments they might be eligible for. A lot of times patients will come in and HER2 low has been a big conversation in the breast world, and so many patients are wondering what they are eligible for with HER2 or what that looks like. So I like to just review it with the patient, pulling out their pathology report.

Benjamin P. Levy, MD: And Kevin, just at a high level of things that you’re looking at in a [patient with] metastatic breast cancer…, what markers are you routinely looking and testing for?

Kevin Kalinsky, MD, MS: As Kayla mentioned, ER/PR/HER2, and this question about HER2 low has transformed how we talk about patients with metastatic disease. It doesn’t have any application right now for patients with early-stage breast cancer but we do discriminate now of HER2 0 or low HER2 positive. For us, this is likely going to change because we’ll see data for the ultra-low population in the DESTINY Breast 06 trial [NCT04494425]. The other thing that I’ll mention just in terms of biomarkers is that we do have some mutations that we have actionable drugs for. For patients with ER+ breast cancer for whom we give a PIK3CA targeted drug or ESR1 mutations with circulating tumor DNA where we now have the approval of elacestrant; we would also think potentially by giving fulvestrant and then like EBV2 [Epstein-Barr virus] mutations. I think in terms of the tumor tissue, the most immediate things that we use reflexively [in] decision-making is ER/PR and HER2, as Kayla mentioned.

Benjamin P. Levy, MD: I already know the answer to this question; I’ll ask it anyway. It’s reflexive and it’s done successfully, correct?… [You] don’t know this, but in lung, we’re always saying, “Why can’t we be more like breast? Why can’t we have reflexive testing and why can it be done?” Do the pathologists do that in all the patients who walk through your door reflexively?

Kevin Kalinsky, MD, MS: I would say that it is. I would say in addition [to other testing]. And don’t get me wrong, in breast cancer, we have other things that we debate about like Ki-67, and all institutions do that in the adjuvant setting, etc. The other thing we experience, which I imagine is something similar, for instance, to in the thoracic world, is that PD-L1 [programmed death ligand-1] testing. For instance, at our institution, we don’t do local testing. We send that off to a commercial partner who does the PD-L1 testing. And I get the sense that there may be some heterogeneity at community and academic sites or even within academic institutions about whether they’re doing their own PD-L1 testing.

Transcript is AI-generated and edited for clarity and readability.