On Feb. 3, 2015, the U.S. Food and Drug Administration (FDA) granted accelerated approval for using the targeted therapy Ibrance (chemical name: palbociclib) in combination with Femara (chemical name: letrozole) to treat locally advanced-stage or metastatic, estrogen-receptor-positive, HER2-negative breast cancer that hadn’t been treated with hormonal therapy before in postmenopausal women.
Ibrance is a cyclin-dependent kinase 4/6 inhibitor. A kinase is a type of protein in the body that helps control cell division. Ibrance works by stopping cancer cells from dividing and growing.
Femara is an aromatase inhibitor, a type of hormonal therapy medicine. Femara works by stopping the production of estrogen in postmenopausal women. This means that less estrogen is available to stimulate the growth of hormone-receptor-positive breast cancer cells.
Both Ibrance and Femara are pills taken by mouth.
The FDA approval is based on results from the PALOMA-1 trial that found that postmenopausal women diagnosed with advanced-stage, estrogen-receptor-positive, HER2-negative breast cancer treated with the combination of Ibrance and Femara lived twice as long without the cancer growing compared to women who got only Femara. Doctors call the length of time a woman lives without the cancer growing “progression free survival.”
- Women who got Ibrance plus Femara lived about 20.2 months before the cancer grew.
- Women who got Femara alone lived about 10.2 months before the cancer grew.
In the PALOMA-1 trial, Ibrance didn’t cause any new or unexpected side effects. The most common side effects seen in the study were:
- neutropenia (low white blood cell count)
- anemia (low red blood cell count)
If you’re a postmenopausal woman who’s been diagnosed with advanced-staged, estrogen-receptor-positive, HER2-negative breast cancer that hasn’t been treated with hormonal therapy yet, you may want to ask your doctor about the approval of Ibrance and whether the combination of Ibrance and Femara makes sense for you and your unique situation.
Editor’s Note: On April 4, 2019, the FDA expanded the use of Ibrance so the medicine now can be used to treat men diagnosed with advanced-stage or metastatic hormone-receptor-positive, HER2-negative breast cancer.