Immunotherapy for Breast Cancer: Current Success and Future Directions

Jump To Section

• Immunotherapy in Breast Cancer Overview
• Checkpoint Inhibitors Response Differences
• Triple-Negative Breast Cancer Immunotherapy
• Keynote Adjuvant Trial Results
• Future of Breast Cancer Immunotherapy
• Full Transcript

Immunotherapy in Breast Cancer Overview

Immunotherapy represents a major advancement in modern oncology. Dr. Marc Lippman, MD, a leading expert in the field, provides crucial insights into its application for breast cancer. Patients and advocates are often highly enthusiastic about immunotherapy approaches. They feel their immune system has failed them and seek new treatment options.

Dr. Marc Lippman, MD, explains that current breast cancer immunotherapy primarily involves checkpoint inhibitors. These drugs work by blocking proteins that prevent immune cells from attacking cancer cells. The immune response to breast cancer differs significantly from other cancer types.

Checkpoint Inhibitors Response Differences

Immunotherapy results vary dramatically between cancer types according to Dr. Marc Lippman, MD. Melanoma and small cell lung cancer patients sometimes achieve prolonged complete responses with checkpoint inhibitors. These responses can persist even after stopping treatment, representing a potentially curative outcome for metastatic disease.

Dr. Marc Lippman, MD, emphasizes that breast cancer responses to immunotherapy are qualitatively different. The immune system activation doesn't produce the same miraculous results seen in other cancers. Metastatic melanoma patients can achieve five-year survival milestones, which was previously unheard of in oncology.

Triple-Negative Breast Cancer Immunotherapy

Triple-negative breast cancer shows the greatest responsiveness to immunotherapy among breast cancer subtypes. Dr. Marc Lippman, MD, notes that even in this more responsive population, results remain modest. Checkpoint inhibitors may produce mild increases in response rates for metastatic triple-negative breast cancer.

Treatment duration improvements are also typically incremental rather than transformative. Dr. Anton Titov, MD, discussed these limitations with Dr. Lippman during their conversation. The immune system interactions with triple-negative breast cancer appear fundamentally different from other cancer types.

Keynote Adjuvant Trial Results

The recent Keynote clinical trial represents a significant development in breast cancer immunotherapy. Dr. Marc Lippman, MD, discusses this practice-changing study published in the New England Journal of Medicine. The trial investigated checkpoint inhibitors for triple-negative breast cancer in the adjuvant setting.

Dr. Marc Lippman, MD, confirms the data are positive and will change clinical practice. Most oncologists will now add immunotherapy to standard treatment regimens. However, he notes important limitations: survival data remains unavailable, and the improvement is stepwise rather than miraculous.

Future of Breast Cancer Immunotherapy

Breast cancer requires different immunotherapy approaches according to Dr. Marc Lippman, MD. Current checkpoint inhibitors alone may not produce the dramatic responses seen in other cancers. The unique aspects of breast cancer immunology need further investigation and understanding.

Dr. Marc Lippman, MD, believes future success will come from other forms of immunotherapy. Combination approaches or novel immune-modulating agents may unlock better responses. Dr. Anton Titov, MD, and Dr. Lippman agree that while progress is being made, breast cancer immunotherapy remains a developing field with significant potential for advancement.

Full Transcript

Dr. Marc Lippman, MD: Immunotherapy is making huge advances in several cancers. Immunotherapy is certainly applied in breast cancer. You did some important work on the estrogen receptor and immunotherapy of breast cancer. You studied the estrogen receptor signaling in suppressing the immune response to cancer.

Dr. Anton Titov, MD: Could you discuss immunotherapy in breast cancer treatment?

Dr. Marc Lippman, MD: Immunotherapy in breast cancer is very attractive. People love it. Most women are advocates for immunotherapy. They feel that their immune system has failed them. They're very excited about immunotherapy clinical trials.

You can look at the class of immunotherapy drugs for breast cancer. The only immunotherapy drugs for breast cancer right now are the checkpoint inhibitors, in my opinion. In that case, the data are qualitatively—not quantitatively—different for breast cancer versus other tumors.

Suppose you look at checkpoint inhibitors given to patients with small cell lung cancer, patients with melanoma, cancers like that. Not all patients benefit from immunotherapy. But many of the cancer patients who benefit have prolonged, complete responses that can persist after you stop the immunotherapy.

Something has been set in motion in those tumors that has unblocked the immune system and has led to complete control of those tumors. It's miraculous. It's wonderful. Unfortunately, it doesn't apply to all patients with melanoma.

But there is a tremendous subset of these patients who now are five years or more out with metastatic melanoma, which used to be an absolute death sentence. Isn't it wonderful?! Breast cancer doesn't do that.

Take the checkpoint inhibitors, even for triple-negative breast cancer, which is more responsive to immune therapies, in the metastatic setting. You can see some mild increases in response rate or duration of response. But immunotherapy results in breast cancer, in my opinion, are not tremendous.

Immunotherapy results are not maintained for long periods in breast cancer. Now, just this week, the Keynote clinical trial was published in the New England Journal of Medicine. It looked at an immune checkpoint inhibitor in triple-negative breast cancer in the adjuvant setting. And the data are positive. And it is practice-changing.

I've discussed this with my colleagues, and most of them say, "Okay, we're going to do this. We're going to add the immunotherapy to breast cancer." But there's no survival data yet. And if you look at the overall outcome, it's not miraculous. It's an improvement. It's a stepwise improvement.

I'm not trying to denigrate it. And I'm not trying to say not to do it. But it does appear that there are other aspects of the immune system in breast cancer, which appear qualitatively different from many other kinds of cancer.

These differences have yet to be completely worked out. And so, I think it's going to require other kinds of interventions, other forms of immunotherapy potentially, to get breast cancer to respond right now. I just don't think immunotherapy is the same success story that we see in other tumor types.