Many treatments are available for breast cancer. Which treatments may work best for you depends on many factors, including the type of breast cancer you have and certain features of the cancer cells. One common type is hormone receptor-positive (HR-positive), HER2-negative breast cancer. In this type of breast cancer, hormones such as estrogen can help the cancer cells grow.
For HR-positive, HER2-negative breast cancer that is advanced or has spread to other parts of the body (metastatic), treatment often includes two types of medicines. One is an aromatase inhibitor, a type of hormone therapy that lowers estrogen levels. The other is a CDK4/6 inhibitor, a targeted medicine that blocks proteins that help cancer cells grow.
Over time, however, the cancer can change in ways that make hormone therapy less effective. One such change is a mutation in a gene called ESR1.
Etcamah (camizestrant) is a hormone therapy used for certain adults with HR-positive, HER2-negative advanced or metastatic breast cancer that has an ESR1 mutation. It is used when the mutation is found during treatment with an aromatase inhibitor and a CDK4/6 inhibitor. Etcamah replaces the aromatase inhibitor and is taken along with a CDK4/6 inhibitor, such as abemaciclib (Verzenio), palbociclib (Ibrance), or ribociclib (Kisqali).
Keep reading to learn how Etcamah works, how to take it, and the benefits seen in clinical studies.
How Does Etcamah Work?
Etcamah is a hormone therapy. HR-positive breast cancer cells have receptors that estrogen can attach to. When estrogen attaches to these receptors, it sends signals that can help the cancer cells grow. Hormone therapies interfere with this process in different ways.
Aromatase inhibitors, such as anastrozole and letrozole, lower the amount of estrogen in the body. This leaves less estrogen available to stimulate the cancer cells. However, over time, some cancers can become resistant to this treatment.
One way this can happen is through a change, or mutation, in a gene called ESR1. This gene provides instructions for making estrogen receptors. An ESR1 mutation can cause these receptors to become overactive, allowing them to continue sending growth signals even when estrogen levels are low.
Specifically, Etcamah is an estrogen receptor antagonist and a type of medicine known as a selective estrogen receptor degrader (SERD). Unlike aromatase inhibitors, which lower estrogen levels, Etcamah targets the estrogen receptors themselves. It blocks the receptors and causes them to break down, reducing signals that can help breast cancer cells grow.
Etcamah is taken along with a CDK4/6 inhibitor, such as abemaciclib, palbociclib, or ribociclib. CDK4/6 inhibitors block different proteins involved in cancer cell growth. Together, the medicines interfere with cancer growth in different ways.
How Do I Take Etcamah?
Etcamah is a tablet that’s typically taken by mouth once daily. The recommended dose is 75 mg.
Tips for taking Etcamah:
- Take it around the same time every day, with or without food.
- Swallow the tablet whole. Do not cut, crush, or chew it, and don’t take tablets that are broken, cracked, or damaged.
- If you miss a dose by six hours or less, take the missed dose as soon as you remember.
- If you miss a dose by more than six hours, skip the missed dose, and take your next dose at the usual time.
- If you vomit after a dose, do not take another one. Just take your next dose at the usual time.
- Do not take two doses at the same time to make up for a missed or vomited dose.
Etcamah is usually taken with a CDK4/6 inhibitor, such as abemaciclib, palbociclib, or ribociclib. Your health care provider will tell you how and when to take each medicine and how long to continue treatment.
The recommended dose may be different if you have liver problems, depending on which CDK4/6 inhibitor you take with Etcamah. Your health care provider may also change or pause your treatment if you have certain side effects.
Etcamah can interact with certain medicines, which may affect how you take your treatment. Make sure your health care provider knows about all prescription and over-the-counter medicines, vitamins, and supplements you use. Learn more about Etcamah drug interactions here.
How Was Etcamah Studied?
Etcamah was studied in a clinical trial called SERENA-6. The study included people with estrogen receptor-positive, HER2-negative advanced or metastatic breast cancer who had already received at least six months of treatment with an aromatase inhibitor plus a CDK4/6 inhibitor. Researchers used blood tests every two to three months to look for ESR1 mutations.
People who had an ESR1 mutation detected before their cancer had gotten worse could enter the treatment phase of the study. A total of 315 people were randomly assigned to one of two groups:
- One group switched from their aromatase inhibitor to Etcamah while continuing their CDK4/6 inhibitor.
- The other group continued taking their aromatase inhibitor and CDK4/6 inhibitor.
The CDK4/6 inhibitors included abemaciclib, palbociclib, and ribociclib, with palbociclib being the most commonly used.
The middle (median) age of study participants was 61 years, with ages ranging from 29 to 89 years. Nearly all participants (99%) were female. About 63% were White, 23% were Asian, and 2% were Black. About 79% of the female participants were postmenopausal, while 20% were premenopausal or perimenopausal.
More than half (57%) had cancer that had not spread to internal organs, and 63% had already been taking an aromatase inhibitor plus a CDK4/6 inhibitor for at least 18 months.
The main goal of SERENA-6 was to compare progression-free survival (PFS). This measures how long people live without their cancer getting worse.
What Benefits Were Seen With Etcamah?
Overall, the SERENA-6 trial found that Etcamah helped people go longer without their cancer getting worse, compared with continuing an aromatase inhibitor.
Median PFS was:
- 16 months for people who switched to Etcamah and continued their CDK4/6 inhibitor
- 9.2 months for people who continued their aromatase inhibitor and CDK4/6 inhibitor
Overall, switching to Etcamah reduced the risk of cancer progression or death by 56% during the study period.
At the time of this analysis, there was not yet enough information to know whether Etcamah helped people live longer overall.
A later analysis with longer follow-up continued to show a benefit. Median PFS was 16.8 months with Etcamah plus a CDK4/6 inhibitor, compared with 9.2 months for people who continued their aromatase inhibitor. At two years, about 35% of people taking Etcamah had not had cancer progression, compared with about 14% of those who continued their aromatase inhibitor.
Your results with Etcamah may be different from those seen in the clinical trial.
Note that Etcamah received accelerated FDA approval based on how long it helped keep the cancer from getting worse. More research is needed to confirm its benefits, and full FDA approval may depend on the results of additional studies.
What Monitoring Will I Need?
Before starting Etcamah, your health care provider will use a special test to confirm that your breast cancer has an ESR1 mutation.
Your heart will also need to be checked before and during treatment. Etcamah can slow your heart rate and affect the electrical activity that controls your heartbeat. Your health care provider will check your heart rate and use a test called an EKG to check your heart rhythm. Blood tests may also be used to check the levels of certain minerals, called electrolytes, that can affect your heartbeat.
Keep your appointments for monitoring while taking Etcamah, and let your health care provider know about any new or worsening symptoms. Learn more about Etcamah side effects here.
Is There Any Cost Assistance Available?
How much Etcamah costs will depend on your insurance coverage and whether you qualify for financial assistance. The drugmaker AstraZeneca offers programs that may help you navigate insurance coverage and lower your out-of-pocket cost. Visit this website or call 844-275-2360 to speak with a representative about support options.
