Mariana Chavez Mac Gregor, MD, MSC, University of Texas, MD Anderson Cancer Center, highlights her approach to treating patients with metastatic HER2+ breast cancer. 

Transcript

My name is Mariana Chavez Mac Gregor. I am a breast medical oncologist. I am an associate professor at the University of Texas MD Anderson Cancer Center. I am going to tell you a little bit today about how I treat patients with metastatic HER2-positive breast cancer.

I think there are some important things to remember. One is that these patients, with the new targeted therapies that we have available can have extraordinary outcomes.

It is important to remember the value of the multidisciplinary care, and of course, the importance of adequate pathology review -at the time of first recurrence or at diagnosis if it's stage IV de novo- and make sure that patients have HER2-overexpressed tumors according to the ASCO/CAP guidelines.

I think we have very strong data to support that the first-line treatment for these patients, is docetaxel and  dual anti-Her2 blockade with pertuzumab and trastuzumab, based on the results from the CLEOPATRA trial. My patients will continue 6 -8 cycles of docetaxel, and then I will stop the chemotherapy and continue maintenance with the two anti-HER2 antibodies.

In the second line, it is quite clear that the best next treatment in terms of progression free survival (PFS)  and overall survival (OS), is T-DM1.  Based on the results from the EMILIA trial, my patients will receive T-DM1 second line.

In the third line, fortunately now, we have more options than what we had just a year ago. Before the approval of some new exciting agents, our patients will continue receiving treatment with trastuzumab plus different chemotherapies or a TKI like lapatinib. I think that today some of the agents that we are very excited about include tucatinib and trastuzumab-deruxtecan.

We have other drugs like neratinib and margetuximab that have also been approved that I may not incorporate that early. In the third-line setting, particularly for those patients that have CNS disease, the next best treatment is going to be tucatinib in combination with trastuzumab and capecitabine based on the results of the HER2CLIMB study.

The data on trastuzumab deruxtecan, it is incredibly exciting. I have used the drug in both third and fourth-line setting, having seen great benefit on my patients. Those are drugs that we can use in sequence.

Of course, we always have to individualize, make sure that patients who have bone disease are receiving a bone agent and that we are assessing the individual needs, symptoms, and toxicities of our patients. In the HER2-positive world, we have now a number of agents that give us extraordinary outcomes and a lot of options for our patients.

Something that I often use, and I want not to forget to mention it,  is that it can be possible that in the fifth-line setting or sixth-line setting, we have patients that have never been treated with anthracyclines. I do believe that some of these HER2-positive tumors are quite sensitive to TROP-2 inhibition. In some of my patients, without combination with anti-HER2 therapy, I have used single-agent lysosomal doxorubicin with very good results. I'm not advocating for that to be used in the beginning since we have so many incredible agents. It is something that from time to time, when we are running out of options, can be helpful.

Of course, it all depends on the desires of the patients, the goals of treatment, the performance status. Overall, that is how I will, in general, treat many of my patients with HER2-overexpressed tumors.