Ibrance is a potent and selective inhibitor of cyclin-dependent kinases (CDKs) 4 and 6, which complex with a regulatory protein, called cyclin, to control cancer cell cycling. The FDA has approved it for use in the treatment of metastatic breast cancer.
Breast cancer is the second most common type of cancer among women in the United States. It forms in the breast tissue and in more advanced stages, can invade normal surrounding tissue or metastasize to distant areas of the body. According to the National Cancer Institute, approximately 232,670 American women were diagnosed and 40,000 died from breast cancer in 2014.
Ibrance is a potent and selective inhibitor of cyclin-dependent kinases (CDKs) 4 and 6, which complex with a regulatory protein, called cyclin, to control cancer cell cycling. This process, which is frequently disrupted in breast cancer, plays a critical role in production of cancer cells and in the development of therapeutic resistance.
Ibrance is approved in postmenopausal women with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer who have not yet received an endocrine-based therapy. It is to be used in combination with letrozole, an aromatase inhibitor also approved to treat breast cancer in postmenopausal women.
“This approval represents the first treatment advance for this group of women in more than 10 years. It’s exciting to think about the potential of this new medicine to help so many patients with advanced disease,” said Mace Rothenberg, MD, senior vice president, clinical development and medical affairs, and chief medical officer, Pfizer Oncology.
FDA granted Ibrance breakthrough therapy designation.
The drug’s approval was based on a clinical study which included 165 postmenopausal women with ER-positive, HER2-negative breast cancer who had not received previous treatment for advanced disease. Participants were randomly assigned to receive either Ibrance in combination with letrozole or letrozole alone. Patients treated with Ibrance plus letrozole had a progression-free survival of about 20.2 months compared to 10.2 months for patient treated with letrozole alone. Information on overall survival is not available at this time.
Some of the most common side effects associated with the use of Ibrance included neutropenia, leukopenia, anemia, upper respiratory infections, hair loss, diarrhea, thrombocytopenia, decreased appetite, and peripheral neuropathy. Healthcare professionals should notify patients of these risks and monitor patient blood counts as clinically indicated.