Kisqali (chemical name: ribociclib, formerly called LEE011) was approved by the U.S. Food and Drug Administration (FDA) on March 13, 2017 to be used in combination with an aromatase inhibitor to treat advanced-stage or metastatic, hormone-receptor-positive, HER2-negative breast cancer that hasn’t been treated with hormonal therapy yet in postmenopausal women.
Like Ibrance (chemical name: palbociclib), Kisqali is a cyclin-dependent 4/6 kinase inhibitor. A kinase is a type of protein in the body that helps control cell division. Ribociclib works by stopping cancer cells from dividing and growing. Kisqali is a pill taken by mouth.
Advanced-stage breast cancer is breast cancer that has spread to tissue near the breast, such as the chest wall. Metastatic breast cancer is cancer that has spread to parts of the body away from the breast, such as the bones or liver. Metastatic breast cancer is also considered advanced-stage disease.
An aromatase inhibitor is a type of hormonal therapy medicine used to treat hormone-receptor-positive breast cancer. There are three aromatase inhibitors:
- Arimidex (chemical name: anastrozole)
- Aromasin (chemical name: exemestane)
- Femara (chemical name: letrozole)
The FDA approval was based on results from the MONALEESA-2 study, which found that Kisqali given in combination with Femara offered more benefits in treating advanced-stage, hormone-receptor-positive, HER2-negative breast cancer than Femara alone. In the study, postmenopausal women treated with Kisqali and Femara had a 44% lower risk of the cancer growing than women treated with Femara alone.
"In the MONALEESA-2 trial, ribociclib plus letrozole reduced the risk of disease progression or death by 44% over letrozole alone, and more than half of patients (53%) with measurable disease taking ribociclib plus letrozole experienced a tumor burden reduction of at least 30%. This is a significant result for women with this serious form of breast cancer," said Gabriel N. Hortobagyi, M.D., professor of medicine at the University of Texas MD Anderson Cancer Center and lead researcher of the MONALEESA-2 study. "These results affirm that combination therapy with a CDK4/6 inhibitor like ribociclib and an aromatase inhibitor should be a new standard of care for initial treatment of HR+ advanced breast cancer."
Like almost all cancer treatments, Kisqali can cause side effects, some of them severe. The most common side effects of Kisqali are:
- hair loss
- back pain
- low white blood cell counts
Kisqali also may cause a heart problem known as QT prolongation. This condition can cause an abnormal heartbeat and can be fatal. Tell your doctor right away if you have a change in heartbeat, including a fast or irregular heartbeat, or if you feel dizzy or like you might faint.
Kisqali also may cause serious liver problems. Tell your doctor right away if you have any of the following signs of liver problems:
- yellowing of the skin or the whites of the eyes
- dark or brown urine
- feeling very tired
- loss of appetite
- pain on the upper right side of the abdomen
- bleeding or bruising more easily than normal
If you’re taking Kisqali, you should avoid pomegranates/pomegranate juice and grapefruit/grapefruit juice because they can interact with Kisqali.
If you’ve been diagnosed with advanced-stage, hormone-receptor-positive, HER2-negative breast cancer and are deciding on treatments, you may want to talk to your doctor about Kisqali or Ibrance and ask if treatment with one of these targeted therapies in combination with Femara makes sense for your unique situation.