The CDK4/6 inhibitor Verzenio (chemical name: abemaciclib) in combination with the hormonal therapy Faslodex (chemical name: fulvestrant) offered better overall survival — about 9 months longer — than Faslodex alone in women diagnosed with advanced-stage, hormone-receptor-positive, HER2-negative breast cancer that had grown while being treated with hormonal therapy, according to the latest results from the MONARCH 2 study.
The research was presented on Sept. 29, 2019, at the European Society for Medical Oncology (ESMO) 2019 Congress and published simultaneously in JAMA Oncology:
- Read an ESMO media release about the study and the presentation abstract.
- Read the JAMA Oncology abstract.
Advanced-stage breast cancer is either locally advanced breast cancer or metastatic breast cancer. Locally advanced breast cancer is breast cancer that has spread to tissue near the breast, but not to parts of the body away from the breast. Metastatic breast cancer is cancer that has spread to parts of the body away from the breast, such as the bones or liver.
Overall survival is how long a person lives, whether or not the cancer grows.
About Verzenio and Faslodex
Verzenio is a cyclin-dependent kinase 4/6 (CDK4/6) inhibitor. A kinase is a type of protein in the body that helps control cell division. Verzenio works by stopping cancer cells from dividing and growing. Verzenio is a pill taken by mouth. Verzenio is used in combination with an aromatase inhibitor as the first hormonal therapy to treat advanced-stage or metastatic, hormone-receptor-positive, HER2-negative breast cancer in postmenopausal women. Arimidex (chemical name: anastrozole), Aromasin (chemical name: exemestane), and Femara (chemical name: letrozole) are aromatase inhibitors.
Verzenio also is used in combination with Faslodex to treat women diagnosed with hormone-receptor-positive, HER2-negative, metastatic or advanced-stage breast cancer if the cancer grew after hormonal therapy treatment.
Verzenio is used alone to treat women and men diagnosed with hormone-receptor-positive, HER2-negative, metastatic or advanced-stage breast cancer if the cancer grew after hormonal therapy treatment and earlier chemotherapy for metastatic disease.
The recommended starting doses of Verzenio are 150 milligrams (mg) twice per day in combination with Faslodex or 200 mg twice per day used alone.
Faslodex is a type of hormonal therapy called an estrogen receptor downregulator (ERD). ERDs block the effects of estrogen in breast tissue. ERDs sit in the estrogen receptors in breast cells. If an ERD is in the estrogen receptor, there is no room for estrogen and it can't attach to the cell. If estrogen isn't attached to a breast cell, the cell doesn't receive estrogen's signals to grow and multiply. ERDs also:
- reduce the number of estrogen receptors
- change the shape of breast cell estrogen receptors so they don't work as well
Faslodex is used:
- alone as the first treatment for postmenopausal women diagnosed with hormone-receptor-positive, HER2-negative, advanced-stage breast cancer that hasn’t been treated with hormonal therapy
- to treat postmenopausal women diagnosed with metastatic, hormone-receptor-positive breast cancer that has stopped responding to other hormonal therapy medicines, such as tamoxifen
Faslodex is given as an injection into a muscle, usually once a month.
About the MONARCH 2 study
In the MONARCH 2 study, researchers randomly assigned 669 women diagnosed with advanced-stage, hormone-receptor-positive, HER2-negative breast cancer that had grown while being treated with a hormonal therapy medicine other than Faslodex to one of two treatments:
- Faslodex plus placebo (a dummy pill that looked just like Verzenio) (223 women)
- Faslodex plus Verzenio (446 women)
None of the women had been treated with chemotherapy for metastatic breast cancer, and the women had been treated previously with only one hormonal therapy medicine. The women were of any menopausal stage: premenopausal, perimenopausal, and postmenopausal.
The women ranged in age from 32 to 91.
In 2017 the U.S. Food and Drug Administration approved Verzenio based on results from MONARCH 2 showing that women treated with Verzenio and Faslodex had better progression-free survival — 7 months — compared to women treated with Faslodex alone.
Progression-free survival is how long the women lived without the cancer growing.
Latest MONARCH 2 results
Besides progression-free survival, the researchers also wanted to know if Verzenio could improve overall survival, which "is really the gold standard for patients," according to Sledge.
The cut-off date for overall survival data analysis was June 20, 2019. About half the women had been followed for less than 48 months and half had been followed for a longer period of time.
At that time, 338 women had died:
- 211 women treated with Verzenio and Faslodex (47%)
- 127 women treated with Faslodex alone (57%)
Median overall survival was:
- 46.7 months for women treated with Verzenio and Faslodex
- 37.3 months for women treated with Faslodex alone
So overall survival was 9.4 months longer for women treated with Verzenio compared to women treated with Faslodex alone.
"Results from the MONARCH 2 study presented 2 years ago showed significant improvement in progression-free survival for patients treated with the combination of abemaciclib plus fulvestrant compared to fulvestrant alone," Sledge said at a media briefing about the study. "Now, with further follow-up, we have overall survival data showing a statistically significant and clinically meaningful improvement in overall survival with the combination."
He continued, "The main take-home message from this study — and from other similar studies — is that CDK4/6 inhibitors significantly prolong the time patients remain in remission and significantly improve overall survival. Therefore it is very reasonable to think of these as standard of care options for patients with metastatic breast cancer."
What this means for you
The results of this study are extremely hopeful. While a 9-month improvement in overall survival may seem small to some of us, it's important to remember that successfully treating breast cancer is a process. These latest MONARCH 2 results are moving the needle in the right direction.
If you've been diagnosed with advanced-stage, hormone-receptor-positive, HER2-negative breast cancer that has grown while being treated with hormonal therapy, you may want to talk to your doctor about this study and ask if treatment with Verzenio and Faslodex makes sense for your unique situation.
For more information on Verzenio and other CDK4/6 inhibitors, visit the Breastcancer.org Targeted Therapies pages.
Written by: Jamie DePolo, senior editor