New Options for HER2+ and Triple-Negative Breast Cancers
- There have been major advances in treating metastatic breast cancer over the past few years.
- Immunotherapy shows promise in triple-negative breast cancer.
- Antibody-drug conjugates, “the next big thing,” extend life in two types of breast cancer.
- Some drugs cross the blood-brain barrier and slow or prevent brain metastases.
Triple-Negative Breast Cancer
Triple negative breast cancer is one of the hardest breast cancers to treat. That's because some of the most effective breast cancer treatments targeted therapies are for HER2-positive or hormone-receptor-positive cancers. Those medications don't help people with triple negative breast cancer. So, advancements in the treatment of this type of cancer are especially exciting.
Read MoreAntibody-Drug Conjugates in Triple-Negative Breast Cancer
In April of this year, the FDA approved sacituzumab govitecan-hziy (Trodelvy) for people with metastatic triple negative breast cancer who had already had two prior treatments. Trodelvy is an antibody-drug conjugate. An anti-cancer drug is attached to an antibody that recognizes cancer cells. People receive the drug by IV. When it enters the bloodstream, the antibodies travel straight to the cancer cells and deliver the anti-cancer drug directly to them. In the ASCENT trial, Trodelvy doubled survival time over chemotherapy. Related: In Triple-Negative Breast Cancer, New Drug Trodelvy Extends Life"The ASCENT trial was a huge success," Lim says. "Something that we haven't seen in triple negative breast cancer for a long time."
Immunotherapy in Triple Negative-Breast Cancer
For years, researchers have tried to find a way to leverage the promise of immunotherapy in breast cancer.
"Immunotherapy has been a new and exciting treatment in lung cancer, melanoma, head and neck cancers, but breast cancer wouldn't respond to immunotherapy, but that's changing now," Lim says.
Dr. Elizabeth Comen discusses chemo and immunotherapy for triple-negative breast cancer.
Several studies in the past year have shown the promise of immunotherapy in triple negative breast cancers that express a protein called PD-L1. PD-L1 on the surface of tumor cells communicates with PD-1 on the surface of immune T cells to convince the immune system not to fight the cancer. Drugs that block PD-1 or PD-L1 help the immune system see the cancer for the threat that it is and launch an attack.
Early last year, the FDA approved PD-L1 blocker atezolizumab (Tecentriq) in combination with chemotherapy for metastatic triple-negative breast cancer that expresses PD-1. The drug combo is for people whose cancer is metastatic or locally advanced and inoperable. More recent studies show that a similar drug, PD-1 blocker pembrolizumab (Keytruda), may also extend survival in metastatic triple-negative breast cancer.
HER2-Positive Breast Cancers
HER2-positive breast tumors express a protein called human epidermal growth factor receptor 2 that helps the cancer grow. Targeted drugs, such as Herceptin, can prevent the protein from further fueling the cancer. But, the cancer still advances in some people, and more treatment options are needed.
Kinase Inhibitors in HER2-Postive Brain Metastases
HER2-positive breast cancer commonly metastasizes to the brain. But, women who have brain metastases usually aren't eligible for clinical trials. New studies, however, show that drugs called kinase inhibitors, tucatinib and neratinib, can cross the blood-brain barrier and extend the lives of women whose cancer has spread to the brain.
Dr. Elizabeth Comen talks treatment options for metastatic HER2-positive breast cancer.
"This is huge," says Lim. "These people were typically excluded from clinical trials, but the tucatinib + Herceptin + xeloda trial proved that they could be treated. This is great news for the patient."
Antibody-Drug Conjugates in HER2-Positive Breast Cancer
The FDA approved an antibody-drug conjugate for HER2-positive breast cancer in the past year, too. This drug, fam-trastuzumab deruxtecan-nxki (ENHERTU), attaches trastuzumab (Herceptin) to an antibody that delivers the drug directly to the cancer cell.
Related: Hopeful News for Breast Cancer: New Drug Combination to Extend Survival Time
"These drugs release chemotherapy to HER2+ cells and some of the neighboring cells, which are not HER2+ but can contribute to the cancer progression, and they have shown great activity against the cancer," Lim says.
In fact, antibody-drug conjugates aren't only useful in breast cancer, Lim says. "The antibody-drug conjugate is going to be the next big thing coming up not only in breast cancer but all of the cancer drugs."
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