Ibrance is meant to treat postmenopausal women with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer that have not been treated with endocrine therapy.
This type of malignancy is caused by cancerous cells in the breast tissue that tend to spread to the surrounding tissue. Ibrance has the capacity to block cyclin-dependent kinases (CDKs) 4 and 6, two molecules responsible for cancer cell proliferation.
“The addition of palbociclib to letrozole provides a novel treatment option to women diagnosed with metastatic breast cancer,” said the director of the Office of Hematology and Oncology Products in the FDA’s Center for Drug Evaluation and Research, Richard Pazdur, M.D., in a press release from the agency. “The FDA is committed to expediting marketing approval of cancer drugs through our accelerated approval regulations.”
Pfizer conducted a study including 165 postmenopausal women with ER-positive, HER2-negative advanced breast cancer, which had not previously been treated for advanced disease. These women were randomly administrated either Ibrance in combination with letrozole or letrozole alone. The results revealed that ibrance and letrozole improved survival for 20.2 months, without disease progression, while letrozole only improved survival for a median of 10.2 months.
Ibrance is a therapy used in combination with letrozole, another drug that has already been approved by the FDA for the treatment of a series of breast cancer types in postmenopausal female patients. Pfizer’s drug had already been granted the FDA’s designation of breakthrough therapy due to its results of preliminary studies conducted, revealing the drug’s efficacy when compared to currently available therapies. In addition, the drug had also been granted priority review status, a designation that gives expedited review to drugs expected to improve safety or effectiveness in the treatment of a serious condition or meet an unmet medical need.
According to the press release, Ibrnace’s side effects included a decrease in infection-fighting white blood cells called neutrophils (neutropenia), low levels of white blood cells (leukopenia), fatigue, low red blood cell counts (anemia), upper respiratory infection, nausea, inflammation of the lining of the mouth (stomatitis), hair loss (alopecia), diarrhea, low blood platelet counts (thrombocytopenia), decreased appetite, vomiting, lack of energy and strength (asthenia), damage to the peripheral nerves (peripheral neuropathy) and nosebleed (epistaxis).