Breast Cancer Challenges and Promises in Immunotherapy

Mei Wei, MD, an oncologist specializing in breast cancer at Huntsman Cancer Institute at the University of Utah, participated in the Denver Regional Institute for Value-Based Medicine^® event and contributed to the session on new treatments for hormone receptor–positive (HR+)/HER2- breast cancer.

Wei spoke with The American Journal of Managed Care^® to emphasize the impact CDK4/6 inhibitors and antibody-drug conjugates will have on the outcomes of patients with HR+/HER2- breast cancer. She highlights how checkpoint inhibitors like pembrolizumab have shown efficacy in specific settings, while managing immune-related adverse events.

This transcript was lightly edited for clarity.

Transcript

How are new treatments impacting patient outcomes, and what are the long-term implications?

This is very exciting because the ADCs, all of the targeted therapies, I think significantly improve the outcome.

Historically, in the metastatic setting, before the CDK4/6 inhibitor was approved, patients had a much shorter overall survival. However, now with the CDK4/6 inhibitor, the overall survival among all the CDK4/6 inhibitors is about 50 to 60 months, that's about 5 to 6 years on average.

After that, a patient can use ADCs and other chemotherapy, putting all of those together in an [endocrine receptor]–positive metastatic breast cancer. I think we can pretty reasonably bring them to 5, 6, or 7 years of overall survival when putting together [these therapies and] adding on the new ADC benefit. Then in the adjuvant setting, by adding 2 CDK4/6 inhibitors, we don't have the overall survival data yet.

With the monarchE, which is using adjuvant abemaciclib, even though the PFS [progression-free survival] is significantly improved compared with the patient that did not receive abemaciclib. The overall survival does not reach a statistical significance, but probably because the follow-up time is not long enough.

The same situation with the ribociclib. Despite the PFS improvement, we haven't seen the overall survival benefit yet, but we hope with longer follow-up time we can kind of see the trend. But we don't have that data yet.

What are the implications of immune-related adverse events for the use of immunotherapy in breast cancer?

This is another field where we are way behind from our peers. For the melanoma team, they were already using checkpoint inhibitors many years ago. However, for breast, just recently the checkpoint inhibitor has been approved for the triple-negative metastatic and very locally advanced non-metastatic breast cancer.

We are pretty much only familiar with pembrolizumab, although there's many other checkpoint inhibitors under investigation at this point.

We are still learning how to identify the immune checkpoint inhibitor–associated side effects and how to manage those. But we are learning. We've noticed a very high chance of patients developing hypothyroidism with the pembrolizumab. I would say probably even close to 100% of patients would have hypothyroidism when they receive pembrolizumab, and skin rashes and diarrheas.

We are learning all of those, how to recognize the side effects, and how to manage those side effects.