Lines of Therapy: New Drugs May Change MBC Treatment
Which therapy to use for the first, second or third line of treatment for metastatic breast cancer is now under rigorous research as more new therapies are available for treating MBC.
FDA Approves Keytruda®
On November 13, 2020, the FDA approved pembrolizumab (Keytruda®) in combination with chemotherapy for the treatment of patients with locally recurrent unresectable or metastatic triple-negative breast cancer (TNBC) whose tumors express PD-L1 as determined by an FDA approved test.
What is ER-Low Breast Cancer?
Did you know that some breast cancers can be defined as estrogen receptor low (ER-low) breast cancer?
When you’re first diagnosed, a pathologist runs a series of lab tests on the cancer cells to see what drives the breast cancer to grow. Estrogen receptor positive (ER positive) breast cancer cells have proteins that respond to signals from estrogen, telling the cells to grow. Your pathology report will tell you whether the cancer is ER positive, and how many cells in the tumor sample had estrogen receptors.
Right now, any breast cancer with at least 1% of tested cells showing estrogen receptors is considered ER positive. But researchers have found that ER positive cancers that have a low number of cells with estrogen receptors may respond differently to treatment. These breast cancers are called ER-low.
To learn more about reading your test results, understanding ER-low, and what current guidelines are for treating estrogen receptor low breast cancer, see below.
What Do My Test Results Mean?
- How to Read Hormone Receptor Test Results Breastcancer.org explains the two scales used to describe the number of estrogen receptors on cancer cells, and what different results mean.
What Do Current Guidelines Say?
- ASCO and CAP Release Updated Guideline on Estrogen and Progesterone Testing in Breast Cancer The ASCO and CAP guidelines state that every lab should define ER positive as at least 1% of tested cells showing estrogen receptors. They acknowledge ER-low as a distinct group, but for now, this group is treated the same as all other ER+ breast cancer.
Should ER Low Breast Cancers Be Treated With Hormonal Therapy?
- Prognostic and Predictive Value of Low Estrogen Receptor Expression in Breast Cancer This research team found that hormonal therapies may not work as well against ER-low breast cancers.
- Breast Cancer Guidelines Carve Out Category for Low ER Expression It’s unclear whether hormonal therapy is the best treatment option for ER low breast cancers because of a lack of research data. Experts say doctors should talk to people with ER low breast cancers about the pros and cons of getting hormonal therapy.
What Are The Treatment Options for ER-Low Breast Cancer?
- TNBC Clinical Trials For ER-Low Breast Cancer Breast cancers that have any number of estrogen receptors, including those defined as ER-low, are currently treated with hormonal therapies. But some clinical trials for triple negative breast cancer (TNBC) accept people with ER-low cancers. See trials on Metastatic Trial Search that are accepting participants who qualify as ER-low.
- Clinical Trials for ER Positive Breast Cancer People with ER-low breast cancer may also qualify for clinical trials for estrogen positive (ER+) breast cancer. See clinical trials for estrogen positive breast cancer on Metastatic Trial Search.
Recent FDA Approvals for Metastatic Breast Cancer
June 2020
Recent FDA Approvals for Metastatic Breast Cancer
For the past two months, Metastatic Trial Talk brought you the latest about cancer and COVID-19. But while the world focused on coping with the pandemic, the Food and Drug Administration kept drug approvals moving. It approved in April two new medicines for metastatic breast cancer: tucatinib (Tukysa®), for HER2-positive disease, and sacituzumab govetican (Trodelvy®), for triple-negative disease.
Below, read about the FDA approval of each new medicine, who might benefit the most, how the treatments are given and what side effects each may cause. In addition, you’ll find information on the approval of a third drug, trastuzumab deruxtican (Enhertu®), announced in late December.
Tucatinib (Tukysa®)
- CURE: What You Need to Know About the FDA’s Approval of Tukysa for HER2-Positive Breast Cancer
- OncLive (video): HER2CLIMB: IMplications for Brain Metastases in HER2+ mBC
- BreastCancerTrials.org: Open Trials with Tucatinib That Are Recruiting Breast Cancer Patients
Sacituzumab govetican (Trodelvy®)
- Living Beyond Breast Cancer: FDA Approves Targeted Therapy for Metastatic Triple-Negative Breast Cancer
- BreastCancerTrials.org: Open Trials with Sacituzumab Govetican That Are Recruiting Breast Cancer Patients
Trastuzumab deruxtican (Enhertu®)
- OncLive (video): HER2+ mBC: Study Design and Results of DESTINY-Breast01
- Breastcancer.org: FDA Approves Enhertu for Unresectable or Pretreated Metastatic HER2-Positive Breast Cancer
- BreastCancerTrials.org: Open Trials with Trastuzumab deruxtican (DS-8201a) That Are Recruiting Breast Cancer Patients
Relevant Topics on Metastatic Trial Talk (MTT)
Triple-Negative Breast Cancer Update
For women and men with triple-negative breast cancer, chemotherapy has been the primary treatment option. But as scientists learn more about subtypes of triple-negative breast cancer, clinical trials can better match new targeted therapies with specific triple-negative patients. These advances are what led to the FDA approval in March 2019 of the PD-L1 inhibitor atezolizumab (Tecentriq®) to treat women and men with metastatic triple-negative breast cancer whose tumors test positive for PD-L1. And we can expect to see more trials that target specific subtypes of triple-negative cancer in the future.
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- Cancer Therapy Advisor: The First Targeted Therapy For PD-L1+ Metastatic Triple-Negative Breast Cancer
- Breast Cancer Research: Identification of Three Subtypes of Triple-Negative Breast Cancer
- Nature Research: A Novel Approach to Triple Negative Breast Cancer Molecular Classification
- Practice Update: Ladiratuzumab Vedotin Plus Pembrolizumab for Advanced TNBC
- Metastatic Trial Search: Find trials for metastatic triple negative breast cancer
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First Immunotherapy Approved for MBC
Immunotherapies use the body’s immune system to fight cancer. In March, for the first time, the FDA approved an immunotherapy drug as a first-line treatment for metastatic breast cancer.
The drug, Tecentriq® (Atezolizumab), is a type of immunotherapy called a PD-L1 inhibitor. It had already been approved for other types of cancers. The new approval is for treating locally advanced or metastatic triple-negative breast cancer that tests positive for PD-L1 when given along with the chemotherapy drug Abraxane® (nab-paclitaxel). The approval is based on progression-free survival data from the ongoing randomized, phase 3 IMpassion130 study (no longer recruiting as of April 1st, 2019).
In the links below you will find more information about the study findings that led to the drug’s approval.
There is one other immunotherapy that might be an option for a small number of metastatic breast cancer patients. It is the drug Keytruda® (Pembrolizumab), which was approved in May 2017 for patients with any type of metastatic solid tumor that is microsatellite instability-high (MSI-H) or has mismatch repair deficient (dMMR) and has progressed on other treatment. You can learn more about this approval here.
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- Cancer Today: First Immunotherapy Approved for Breast Cancer
- Breastcancer.org: Tecentriq Approved as First Immunotherapy for Breast Cancer
- MedPage Today: Immunotherapy Wins First FDA Approval in Breast Cancer
- OncLive: FDA Issues Alert Regarding Efficacy and Safety of Atezolizumab/Paclitaxel in Breast Cancer
- Metastatic Trial Search: Find Immunotherapy Trials for Metastatic Breast Cancer
Living with Triple Negative MBC
Triple negative breast cancer makes up about 15 to 20 percent of all breast cancer diagnoses.This month we feature three stories by women living with metastatic triple negative breast cancer.
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- SHARE Cancer Support: Karen Peterson
- Living Beyond Breast Cancer: Janice Cowden
You can learn more about triple negative breast cancer on these websites:
Triple Negative Breast Cancer Foundation
National Breast Cancer Foundation: Triple Negative Breast Cancer
CDC: Triple Negative Breast Cancer
You can find clinical trials for Triple Negative Breast Cancer on BreastCancerTrials.org. These trials are also listed on Metastatic Trial Search (MTS)