HER2+ Breast Cancer: Special Challenges and Expert Insight - Episode 6

Screening and Recognition of ILD in HER2+ BC

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Experts in breast cancer respond to polling questions surrounding the recognition of pneumonitis and interstitial lung disease.

Adam Brufsky, MD, PhD: We hinted at the pneumonitis. Let’s ask the audience. Do you screen your HER2+ [human epidermal growth factor receptor 2–positive] breast cancer patients for signs or symptoms of pneumonitis? Yes, only on targeted therapy, only on immunotherapy, only those who are symptomatic, or no? Let’s see what people think. I’ll give them a minute to do this. Pneumonitis is a really important issue. Thankfully, we’re getting some data from other tumor types, including from the 2020 ASCO [American Society of Clinical Oncology Annual Meeting]. Gastric cancer, lung cancers, and bladder cancer are being used for this now. We’re getting some data from our other colleagues who work with other tumor types. Hopefully, we’ll get some more information on this entity. 

The other issue is that we’re not sure what the mechanism is. Let me see the answer to the question, and we’ll talk about the mechanism before we get into the treatment. Interestingly, 50% said only those who are symptomatic. We’ll talk about that in a minute, but let’s first talk about the mechanism. Do you guys have any idea of what’s going on here? I don’t think anybody knows. Let’s start with Sara.

Sara A. Hurvitz, MD: Pneumonitis was seen in the original trastuzumab study. Dr [Dennis] Slamon talks about this. The lung tissue does have HER2 receptors, so it could just be the cytotoxic components being delivered to lung tissue and causing damage. It doesn’t seem to universally respond to steroids. An immune-based underlying etiology is not entirely clear. I don’t think the mechanism is very well understood.

Adam Brufsky, MD, PhD: What do you think, Neil?

Neil Iyengar, MD: In terms of screening, it’s an interesting question. If the question were phrased, “Are you screening your patients who are on trastuzumab deruxtecan?” my answer would be kind of, because you’re getting a sense of that with their restaging imaging. Also, I do baseline pulmonary function testing on everybody whom I’m starting deruxtecan on. That doesn’t help identify who’s at risk and so forth, but my pulmonary colleagues tell me that establishing a baseline is helpful should symptoms develop. In the setting of somebody in whom I’m not using trastuzumab deruxtecan, I’m not generally screening them for pneumonitis.

Sara A. Hurvitz, MD: Weren’t they asking us if we’re screening for signs or symptoms? I assume most of us ask patients if they have shortness of breath or cough when we see them in follow-up as part of our review of systems. That’s important to do and pay attention to for all these drugs, right?

Neil Iyengar, MD: Yes. If they’re reporting symptoms, of course.

Adam Brufsky, MD, PhD: I completely forgot there were 2 more panel questions, so let me do 2 questions and then we’ll go back to this for a minute. This is a polling question for the audience, and we hinted at it. What would be your first trigger to work up a patient for ILD [interstitial lung disease] who’s on 1 of these drugs? Dyspnea, cough, chest pain, fever, or chest CT findings? Let’s see what people have to say. Dyspnea. No one said chest CT findings. We’ll talk about that in a minute.

Which of the following describes your typical initial response to confirm grade 2—that’s symptomatic—ILD in a patient with HER2+ breast cancer on trastuzumab deruxtecan? Monitoring and steroids, dose reduction and steroids, treatment hold and steroids, treatment discontinuation and steroids, or other? Let’s see what people have to say. Half said treatment discontinuation and steroids, 25% dose reduction and steroids, and 25% treatment hold and steroids.

Transcript edited for clarity.