The targeted therapy Ibrance (chemical name: palbociclib) combined with the hormonal therapy Faslodex (chemical name: fulvestrant) continued to offer better overall survival than Faslodex alone for advanced-stage, hormone-receptor-positive, HER2-negative breast cancer after more than 6 years of follow-up, according to the latest results from the PALOMA-3 trial.
The research was presented at the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting and published online on May 28, 2021, by the Journal of Clinical Oncology:
- Read the ASCO abstract of “Overall survival (OS) with palbociclib (PAL) + fulvestrant (FUL) in women with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC): Updated analyses from PALOMA-3.”
- Read the Journal of Clinical Oncology abstract of “Overall survival (OS) with palbociclib (PAL) + fulvestrant (FUL) in women with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) advanced breast cancer (ABC): Updated analyses from PALOMA-3.”
Overall survival is how long a person lives, whether or not the cancer grows or comes back.
About Ibrance and Faslodex
Ibrance 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. Ibrance — a pill taken by mouth — works by stopping cancer cells from dividing and growing.
Ibrance is approved to be used in combination with a type of hormonal therapy called an aromatase inhibitor to treat advanced-stage or metastatic, hormone-receptor-positive, HER2-negative breast cancer that hasn’t been treated with hormonal therapy before in postmenopausal women or men. Arimidex (chemical name: anastrozole), Aromasin (chemical name: exemestane), and Femara (chemical name: letrozole) are aromatase inhibitors.
Ibrance also is approved to be used in combination with Faslodex to treat advanced-stage or metastatic, hormone-receptor-positive, HER2-negative breast cancer that has grown after being treated with hormonal therapy in women or men. Premenopausal and perimenopausal women who take Ibrance in combination with Faslodex also should be treated with a medicine to suppress ovarian function.
Faslodex is an estrogen receptor downregulator. Faslodex — a liquid injected into a muscle once a month — sits in a breast cell’s estrogen receptor so the cell can’t receive estrogen’s signals to grow and multiply. Faslodex also reduces the number of estrogen receptors and changes the shape of breast cell estrogen receptors so they don’t work as well.
About the PALOMA-3 study
The PALOMA-3 (Palbociclib Ongoing Trials in the Management of Breast Cancer 3) study included 521 women diagnosed with advanced-stage, hormone-receptor-positive, HER2-negative breast cancer that had come back or grown while being treated with hormonal therapy. Half the women were older than 57, and half the women were younger than 57. About 80% of the women were postmenopausal.
The women were randomly assigned in a 2:1 ratio to receive one of two treatments:
- 347 women were treated with Ibrance (125 mg per day for 3 weeks, followed by 1 week off) and Faslodex (500 mg injection every 2 weeks for the first three injections, followed by a 500 mg injection every 4 weeks)
- 174 women were treated with Faslodex plus placebo (a pill that looked just like Ibrance but contained no medicine)
Women who were premenopausal also got Zoladex (chemical name: goserelin), a hormonal therapy medicine that stops the ovaries from making estrogen. Doctors sometimes call this medical ovarian shutdown. In other words, Zoladex made the premenopausal women postmenopausal for the length of the study. Zoladex is given by injection every 4 weeks.
PALOMA-3 results published in 2018 after about 4 years of follow-up found that the combination of Ibrance and Faslodex improved overall survival by about 7 months compared with Faslodex alone.
Results from the latest analysis
The latest analysis of the PALOMA-3 study came after more than 6 years of follow-up.
Overall survival was:
- 34.8 months for women treated with Ibrance and Faslodex
- 28.0 months for women treated with Faslodex alone
After 5 years:
- 23.3% of the women treated with Ibrance and Faslodex were alive
- 16.8% of the women treated with Faslodex alone were alive
The researchers also looked at specific cancer and treatment characteristics to see if combining Ibrance and Faslodex offers more benefits for certain types of breast cancer.
Among the 344 women who had not received prior chemotherapy for advanced-stage breast cancer, overall survival was:
- 39.3 months for women treated with Ibrance and Faslodex
- 29.7 months for women treated with Faslodex alone
Among the 410 women diagnosed with breast cancer that had responded to earlier hormonal therapy treatment, overall survival was:
- 39.7 months for women treated with Ibrance and Faslodex
- 29.5 months for women treated with Faslodex alone
Among the 111 women diagnosed with breast cancer that didn’t respond to earlier hormonal therapy treatment, overall survival was:
- 19.9 months for women treated with Ibrance and Faslodex
- 26.2 months for women treated with Faslodex alone
“An improvement in [overall survival] with palbociclib plus fulvestrant continues to be observed with more than 6 years of median follow up in patients with [hormone-receptor]-positive advanced breast cancer who progressed on prior endocrine therapy,” said principal investigator Massimo Cristofanilli, M.D., professor of medicine at Northwestern University, during his presentation at the 2021 ASCO Annual Meeting. “This prolonged [overall survival] benefit is particularly evident in patients with endocrine-sensitive disease and those with prior exposure to chemotherapy in the advanced setting.”
What this means for you
If you’ve been diagnosed with advanced-stage, hormone-receptor-positive, HER2-negative breast cancer that has grown after being treated with hormonal therapy, this study shows that Ibrance continues to improve overall survival.
You may want to talk to your doctor about this study and ask if treatment with a regimen that includes a CDK4/6 inhibitor, such as Ibrance, Kisqali (chemical name: ribociclib), or Verzenio (chemical name: abemaciclib), may be an option for you and your unique situation.
Read more about CDK4/6 inhibitors.
To discuss treatment options with others who are being treated for advanced-stage disease, join the Breastcancer.org Discussion Board forum Stage IV and Metastatic Breast Cancer ONLY.
Written by: Jamie DePolo, senior editor
Reviewed by: Brian Wojciechowski, M.D., medical adviser
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