Treating Metastatic Breast Cancer with Immunotherapy: Understanding the Breakthrough
“It’s a really promising time to have metastatic breast cancer.”
Metastatic breast cancer is the most advanced stage of breast cancer (also known as stage IV), which means the cancer has spread beyond the breast to other distant parts of the body.
While metastatic breast cancer can’t be cured and is more difficult to treat than early-stage breast cancer, there are many FDA-approved treatment options for metastatic breast cancer available, as well as ongoing research to improve upon current therapies, called clinical trials.
“I always tell patients about all the recent new medications that are targeted, that are brilliant, that are helping people,” says Amy Tiersten, MD, a hematologist and oncologist at the Mount Sinai Hospital in New York City. “It’s just a really promising time to have metastatic breast cancer because people can do well for a long period of time with good quality and quantity of lives.”
Clinical Trials for Metastatic Breast Cancer: Immunotherapy
Breast cancer has historically been considered immunologically silent. New clinical trials and preclinical trials suggest, however, that a treatment called immunotherapy is changing that.
Immunotherapy drugs use the body’s own immune system to attack cancer cells. “Cancer cells have a way of putting a break on the immune system so that the immune system can’t find them and kill them,” says Dr. Tiersten.
Certain types of immunotherapy drugs essentially “take the brakes off” of the immune system to help it kill cancer cells. These drugs belong to a class known as checkpoint inhibitors. “Checkpoint inhibitors are extremely interesting drugs that actually act by jumpstarting a patient’s own immune system to recognize the cancer cells as ‘other,’” says Dr. Tiersten.
What Type of MBC Could Immunotherapy Help Treat?
Checkpoint inhibitors are FDA-approved for treating other cancers, such as lung cancer, melanoma, and kidney cancer. For metastatic breast cancer, checkpoint inhibitors are still in clinical trials. Most of the research has been done on triple-negative breast cancer, a type with cancer cells that don’t have estrogen or progesterone receptors and also don’t make too much of the protein called HER2.
“Immunotherapies work best in cancers that are very mutated and very different from normal cells,” says Dr. Tiersten. “Triple-negative breast cancer cells are the most mutated compared to other subtypes of breast cancer.”
Because triple-negative breast cancer cells don’t have hormone receptors, hormone therapy is not helpful in treating these cancers. And because they don’t have too much of the protein HER2, drugs that target HER2 aren’t helpful either. Chemotherapy, however, can still be useful.
“There are trials that have been done in triple-negative breast cancer and ongoing trials combining the checkpoint inhibitors with chemotherapy,” says Dr. Tiersten. “But the mainstay of treatment is chemotherapy because we don’t have the targeted therapies to different receptors.”
“There’s tons of clinical trials that are looking at the role of newer biologic or targeted therapies to augment the effectiveness of chemotherapy or even use in lieu of chemotherapy for triple-negative breast cancer. It’s a very important area of research,” says Dr. Tiersten
Interested in learning more about or finding a clinical trial for metastatic breast cancer? Click here to use the Cancer Research Institute’s Clinical Trial Finder.
Dr. Tiersten is a professor of medicine, hematology, and medical oncology at the Icahn School of Medicine at Mount Sinai. She sees patients at the Dubin Breast Center.
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I was always tell patients about all the
recent new medications that are targeted,
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that are brilliant,
that are helping people, and
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all the ongoing clinical trials.
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There's FDA approvals of many new
drugs over the last few years,
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and drugs that are on the horizon
which will also be made available.
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So the good news is that we have so
many different options.
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We don't run out of
things to offer people.
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By very definition,
the hypothesis in a clinical trial is that
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we're improving upon
our standard therapies.
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Some of the things that are on
the horizon are immunotherapies.
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So for example, there are drugs which
are called checkpoint inhibitors.
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And those are extremely interesting
drugs that actually act by jump starting
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a patient's own immune system to
recognize the cancer cells as other.
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Cancer cells have a way of putting
a brake on the immune system, so
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that the immune system can't find them and
kill them.
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But some of these drugs are able to
lift that brake on the immune system,
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and unleash a patient's own immune system.
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And to kill the cancer cells that way.
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The checkpoint inhibitors are already
FDA approved for lots of other cancers.
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For example lung cancer, melanoma,
kidney cancer, and others.
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Most of the work at this point for
the checkpoint inhibitors has
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been in triple negative breast cancer,
because the immunotherapys work best
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in cancers that are very mutated and
very different from normal cells.
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And triple negative breast
cancer cells are the most
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mutated compared to other
sub types of breast cancer.
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So there are trials that have been done
in triple-negative breast cancer, and
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ongoing trials combining the checkpoint
inhibitors with chemotherapy.
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But the mainstay of
treatment is chemotherapy,
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because we don't have the targeted
therapies to different receptors.
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However, there's tons of clinical trials
that are looking at the role of newer
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biologic or targeted therapies to
augment the effects of chemotherapy or
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even use in lieu of chemotherapy for
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triple negative breast cancer is
a very important area of research.
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So it's just a really promising time
to have metastatic breast cancer,
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because people can do well for a long time
with good quality and quantity of lives.
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Breast Cancer Hormone Receptor Status. American Cancer Society. (Accessed on May 31, 2018 at https://www.cancer.org/cancer/breast-cancer/understanding-a-breast-cancer-diagnosis/breast-cancer-hormone-receptor-status.html)
Immunotherapy for Breast Cancer. Cancer Research Institute. (Accessed on May 31, 2018 at https://www.cancerresearch.org/immunotherapy/cancer-types/breast-cancer)
Systemic treatment for metastatic breast cancer: General principles. UpToDate. (Accessed on May 31, 2018 at https://www.uptodate.com/contents/systemic-treatment-for-metastatic-breast-cancer-general-principles#H361864774)