COMMENTARY

Three Practice-Informing Breast Cancer Trials From ASCO 2020

Kathy D. Miller, MD

Disclosures

June 18, 2020

This transcript has been edited for clarity.

Hi. This is Dr Kathy Miller from Indiana University in Indianapolis.

Welcome to my favorite work-from-home spot as we think together about the most important breast cancer studies from the 2020 American Society of Clinical Oncology (ASCO) annual meeting. I want to point you to three studies that are important in different ways.

KAITLIN

Many of you will recall that KAITLIN was a fully powered adjuvant trial that substituted trastuzumab emtansine (T-DM1) for taxane and trastuzumab. So instead of a taxane, trastuzumab, and pertuzumab, patients would receive T-DM1 and pertuzumab for that portion of their therapy. This large trial focused heavily on patients with lymph node–positive tumors. It was a negative trial and found no improvement by swapping out the antibody–drug conjugate. There was some improvement in short-term toxicity but no improvement in invasive disease-free survival.

This trial will not change the standard of care, but it does challenge us to think about this population. There is good news buried in this negative trial. These patients, even those with lymph node–positive, HER2-positive disease, had a 3-year invasive disease-free survival rate of 93%-94%. It is illogical to think that we are going to move the needle for that group of patients by piling on more. So the question here is not what more can we do, but how much do we have to do? Can we identify those patients who could have less intensive therapy and less toxicity but still maintain these results?

The recently activated Compass trial, coordinated by the ECOG-ACRIN Research Group, uses a less intensive neoadjuvant approach with the goal of following patients who have a pathologic complete response to see whether we can maintain these incredible disease-free survival results with less intensive therapy.

Adjuvant Capecitabine

I want to point you to another adjuvant trial of capecitabine. I see all of you rolling your eyes, in that we've been down this road before; but this one took a different approach. Instead of adding capecitabine to ongoing anthracycline/taxane-based regimens, this trial looked at a maintenance approach in high-risk, triple-negative patients. And it is a positive trial. A year of maintenance, lower-dose capecitabine substantially reduced the risk for recurrence in these high-risk patients.

This trial will be tough to talk about with our patients. If you put yourself in the patient's position, they've finished surgery, almost certainly needed radiation, and finished sequential anthracycline and taxane-based therapy. A year of maintenance chemotherapy is not going to appeal to all of them, yet I believe they need to hear about these results. Together with you, they need to think about the relative risks and benefits of additional therapy and additional toxicity but with additional benefit.

ECOG 2108

Finally, the ECOG 2108 trial was presented in the plenary session. I gave you a heads-up about this trial before the meeting, and it is equally important now that we have the results.

This trial asks a very important practical question: For our 7%-8% of patients who present with de novo stage IV disease, does local therapy to the primary tumor provide any benefit? The short answer is no. There was not a difference in subsequent progression, and there was not a difference in overall survival.

Not surprisingly, more patients who did not have immediate local therapy developed progressive local disease. But that number was fairly small, and it certainly does not justify routine incorporation of local therapy for those patients with de novo metastatic disease, unless local therapy is needed to deal with symptoms of the local disease.

This is Dr Kathy Miller from Indiana University. I'll be back with you soon.

Kathy D. Miller, MD, is associate director of clinical research and co-director of the breast cancer program at the Melvin and Bren Simon Cancer Center at Indiana University. Her career has combined both laboratory and clinical research in breast cancer.

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