Understanding the ESR1 mutation (ESR1m) and what it can mean for you
An ESR1m can appear after being treated with an endocrine therapy.
On this page:
It’s important to test for an ESR1m to get a better understanding of your options if you progress after your first line of therapy.
What is an ESR1m?
Estrogen receptors (ERs) are proteins found on the surface of or inside breast cells. When estrogen binds to these receptors, it sends a signal that promotes cell growth.
In ER+ breast cancer, ERs play a major role in cancer cell growth and survival.
A mutation is a change in DNA that impacts how proteins such as ERs behave. Treatments targeting ERs, like aromatase inhibitors (AI), may work for a time, but then stop providing a benefit. Nearly 50% of people with metastatic breast cancer (mBC) face this problem because an ESR1m develops.
An ESR1m keeps the ERs “always on” so that the tumor keeps growing.
Before first-line
treatment for mBC
of patients have an ESR1m
After first-line
treatment for mBC
of patients develop an ESR1m following treatment with an AI combined with a CDK4/6i therapy
Ask your doctor about ESR1m testing
Your doctor may do a test to look for an ESR1m if your therapy stops working and they’ve confirmed that your disease has progressed.
Step 1:
Your doctor will likely perform a blood test and send your sample to a lab
Step 2:
The lab will analyze the sample to see if an ESR1m is present
Step 3:
You should get your results in about 1 to 2 weeks, so you and your doctor can determine next steps together
It may be valuable to start the conversation at your next appointment. Ask your doctor about testing.
It’s not uncommon to feel intimidated about speaking up and asking your doctor for a test. But remember that your doctor is your partner in care, and it’s always important to be open and honest about what you’re experiencing.
Actor portrayal.
Here is an example of a sample conversation that may be helpful:
“I recently learned about ESR1 mutations in metastatic breast cancer. Is that something I should be tested for?”
What does an ESR1m mean for you?
If you test positive for an ESR1m, you may not respond as well to certain hormone therapies taken alone or in combination with a CDK4/6i.
Some examples include:
Hormone Therapies
•
Exemestane
•
Letrozole
•
Anastrozole
•
Fulvestrant
CDK4/6i
•
Palbociclib
•
Abemaciclib
•
Ribociclib
You have options, like VEPPANU—a targeted treatment for ESR1m, ER+/HER2− mBC.
Discover VEPPANU
CDK4/6i=cyclin-dependent kinase 4/6 inhibitors; ER+=estrogen receptor-positive; ESR1=estrogen receptor 1; HER2-=human epidermal growth factor receptor 2-negative.
VEP_BC-26081