On Friday, September 13th, 2019, the FDA issued a warning against the entire class of cyclin-dependent kinase 4/6 (CDK 4/6) inhibitor drugs for breast cancer patients. According to the federal agency, these drugs can cause pneumonitis, which is inflammation of the lungs. The condition can cause difficulty breathing and cough, and if left untreated, it can cause irreparable lung damage. In rare cases involving further complications, pneumonitis can lead to respiratory failure and death.
The FDA reviewed several clinical trials and post-market safety databases to come to the conclusion that the risk of pneumonitis extended to the entire CDK 4/6 inhibitor class of breast cancer drugs. One to three percent of patients were found to exhibit symptoms of interstitial lung disease (ILD) and pneumonia after taking the drugs. Pfizer’s Ibrance (palbociclib), Novartis’s Kisqali (ribociclib), and Lilly’s Verzenio (abemaciclib) are all affected by this warning.
“Health care professionals should monitor patients regularly for pulmonary symptoms indicative of ILD and/or pneumonitis,” the FDA said in a statement. “Signs and symptoms may include hypoxia, cough, dyspnea, or interstitial infiltrates on radiologic exams in patients in whom infectious, neoplastic, and other causes have been excluded.”
However, the FDA was quick to add that the benefits of CDK 4/6 inhibitors are likely to outweigh the risks for most cancer patients. The drugs are used along with hormone treatments as a therapy for hormone receptor-positive (HR+) breast cancer, human epidermal growth factor 2-negative (HER2-) breast cancer, and advanced or metastatic breast cancer. In many cases, prolonging a patient’s life and/or fighting cancer to save a patient’s life is worth the possible issue of pneumonitis. However, patients and health care providers should be aware of the risk and on the lookout for symptoms of pneumonitis so that it can be treated.
For patients who develop pneumonitis while taking CDK 4/6 inhibitors, the drug should be discontinued either temporarily or permanently in severe cases.
Ibrance won FDA approval in 2015, followed by Kisqali and Verzenio in 2017. A warning regarding the potential risks of these drugs has been issued in both the U.S. and Japan, and Korea is currently reviewing data to determine whether to issue a warning. CDK 4/6 inhibitor drugs, however, continue to be used around the globe with little issue.
Elizabeth Nelson is a wordsmith, an alumna of Aquinas College in Grand Rapids, a four-leaf-clover finder, and a grammar connoisseur. She has lived in west Michigan since age four but loves to travel to new (and old) places. In her free time, she. . . wait, what’s free time?