Managing Patients With Breast Cancer on T-DM1 Therapy

Kevin Kalinsky, MD, MS: Kandra, if we were to see this patient in clinic, and she’s going to get TDM-1 [trastuzumab emtansine] in the adjuvant setting given her residual disease, what are some things you talk about with the patient when you’re educating them about this therapy?

Kandra Horne, DNP, MSN, WHNP-BC: First, of course, I would look at her past medical history. She does have a history of hypertension and takes baby aspirin daily. We’ll let her know that we will continue to monitor her ejection fraction because of the risk of cardiotoxicity. She will continue to receive it once every 3 weeks. We’ll monitor for that. We’ll look at her lab work because there are some patients whose liver enzymes are elevated. And there’s the potential that she may develop adverse effects from this treatment, such as neuropathy. Of course, I’ll ask her if she is having any residual effects or has developed any neuropathy. I’ll let her know that we’ll continue to monitor not only her cardio ejection fraction but also adverse effects, and that we’ll continue to monitor that every 3 weeks.

Kevin Kalinsky, MD, MS: That’s great. Allison, in terms of adverse events, Kandra highlighted some of the ones that we see in clinic, like cardiac function, neuropathy, platelets, and LFTs [liver function tests]. Is there anything to add? The other question is if there’s anything that would be a good strategy to prevent some of these toxicities.

Allison Butts, PharmD, BCOP: I’ll add a few things to the discussion. In general, we think of TDM-1 [trastuzumab emtansine] as a very well-tolerated agent. Kandra mentioned some of those adverse effects. Some of the things we think about are less prevalent with TDM-1 [trastuzumab emtansine] than even trastuzumab. Things like cardiotoxicity we tend to see a little less with TDM-1 [trastuzumab emtansine] than with trastuzumab. Infusion reactions are far less pronounced than what we see with trastuzumab. In clinical practice, what surprised us when the KATHERINE data came out and we began routinely using adjuvant TDM-1 [trastuzumab emtansine] was that patients tend to tolerate it a little worse in this setting.

In addition to more neuropathy, which is likely residual from neoadjuvant treatment, we found a lot of anorexia, failure to thrive, and fatigue. Some of these things we don’t run into commonly in the metastatic space, but we do in the adjuvant setting. In terms of prevention, optimizing their therapy before starting TDM-1 [trastuzumab emtansine] is a key making sure that if they have residual neuropathy, they’ve had a sufficient break to let some of that resolve. We’re optimizing medication therapy for that. Those have been the key because we’ve had to switch a number of patients back to HP [trastuzumab pertuzumab] maintenance because they haven’t done well on the TDM-1 [trastuzumab emtansine]. That’s based on preexisting toxicities that have been left over.

Kevin Kalinsky, MD, MS: That’s great. You highlighted 1 of the points I wanted to mention: if you have a patient who’s developed a significant neuropathy or who has platelet dysfunction, who can’t get through the TDM-1 [trastuzumab emtansine], resuming their HP [trastuzumab, pertuzumab] is something we would clinically do. In terms of monitoring, I’m going to open this for discussion. Kandra already mentioned the continuation of checking echocardiograms. Is there anything else that everybody does? I presume you’re checking blood before you’re looking at the platelets, doing a CBC [complete blood count] and LFTs. Is there anything else you’re doing before the infusions?

Komal Jhaveri, MD, FACP: I agree with Allison. Other than checking the blood and making sure the echocardiograms are up to date, when we meet the patients and do physical exams and take histories, 1 we thing we do is confirm they’re better for neuropathy and how much struggle they have with peripheral neuropathy. About 20% to 25% of patients struggle with that a little, so we have to intervene when it comes to neuropathy, whether it’s optimizing their supportive management, holding therapy for 1 cycle, or even considering dose reduction before we switch back to HP [trastuzumab, pertuzumab]. Short of that, we’ve covered it all.

Transcript edited for clarity.