Optimizing Quality of Life in HER2+ Metastatic Breast Cancer

Announcer: 
Welcome to On the Frontlines of Metastatic Breast Cancer on ReachMD. On this episode, we’ll hear from Dr. Megan Kruse, who’s a medical oncologist at Cleveland Clinic in Ohio. She’ll discuss side effect management in patients being treated for metastatic breast cancer. Here’s Dr. Kruse now.

Dr. Kruse:
So trastuzumab deruxtecan and tucatinib are two common drugs that we use for the treatment of HER2-positive metastatic breast cancer. When we think about their side effects, both the way that they are given—whether it’s pill or IV—and their general drug class that they fall into have a lot to do with the types of side effects that we expect.

So, starting with tucatinib, this is what we call a small molecule targeted inhibitor. So it’s one of our most potent drugs to help with cancer, but it does have its own unique side effects. Because it’s a pill, we often think about nausea being something that patients may experience close to taking the pill. So it often helps if patients, before they take their tucatinib pill, take some antinausea medication so it’s in their system around the same time. Many patients will often feel that having a little bit of food in their stomach also helps.

Tucatinib is definitely one of the drugs we think of that can cause diarrhea. And so we will educate patients to have antidiarrheal medications like loperamide at the ready to be able to use once they try the tucatinib, and to maintain really good hydration. So keeping up with water intake and electrolyte intake is really important.

We keep a close eye on the liver function tests for patients on tucatinib. It is a drug that can cause some inflammation of the liver, and so if we’re starting to see that, we may have to do dose adjustments, even if a patient feels well, in order to keep them from having any complications of being on the medication.

In contrast, trastuzumab deruxtecan tends to carry a lot more chemo-type side effects. So the side effects we think about with this—we definitely pay attention, again, to those gastrointestinal side effects, so we medicate before the treatment is given for nausea and make sure that patients have good antinausea medications at home. We pay attention to both diarrhea or constipation—this is one drug that can cause either depending on the patient.

And then in terms of the other places in the body, we monitor the heart function while patients are on this drug with ultrasounds of the heart every three to six months to make sure that the squeezing or pumping function of the heart is still good. That’s a very rare but real consequence that can happen from being on trastuzumab deruxtecan. Another rare but real side effect is inflammation of the lungs. And so this is something that can happen without causing symptoms that your doctor may just see on CAT scans or PET scans. If that’s the case, we typically would treat it with steroids and hold the drug until things look better. If you’re actually having respiratory side effects from being on trastuzumab deruxtecan—so that could be cough or shortness of breath—that’s actually a time where we hold the medication, and usually, we do not rechallenge or retreat with the medication because we’d be worried about lasting potential damage to the lungs.

So both tucatinib and trastuzumab deruxtecan are both known to improve survival for women with HER2-positive metastatic breast cancer. The drugs themselves have never actually been compared head-to-head in a clinical trial, and most of our patients actually would receive both of these drugs at some point during their cancer treatment journey. Both medications should have reasonable quality of life for patients, and as we control the cancer better, patients’ quality of life should actually get better.

Announcer:
That was Dr. Megan Kruse talking about managing treatment side effects in patients with metastatic breast cancer. To access this and other episodes in our series, visit On the Frontlines of Metastatic Breast Cancer on ReachMD.com, where you can Be Part of the Knowledge. Thanks for listening!