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FDA Approves Breast Cancer Drug Ibrance (Palbociclib)
The FDA has granted accelerated approval to Ibrance (palbociclib, Pfizer) to treat advanced (metastatic) breast cancer.
Breast cancer in women is the second most common type of cancer in the U.S. The National Cancer Institute estimates that 232,670 American women were diagnosed with breast cancer and that 40,000 died from the disease in 2014.
Palbociclib works by inhibiting cyclin-dependent kinases (CDKs) 4 and 6, which are involved in promoting the growth of cancer cells. The treatment is intended for postmenopausal women with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer who have not received an endocrine-based therapy. It is to be used in combination with letrozole (Femara, Novartis), another FDA-approved product used to treat certain kinds of breast cancer in postmenopausal women.
The FDA granted Ibrance a “breakthrough therapy” designation because the sponsor (Pfizer) demonstrated through preliminary clinical evidence that the drug may offer a substantial improvement over available therapies. It also received “priority review” status, which allows an expedited review of drugs intended to provide a significant improvement in safety or effectiveness in the treatment of a serious condition or to meet an unmet medical need.
Ibrance was approved more than 2 months ahead of the prescription drug user fee goal date of April 13, 2015, the date when the agency was scheduled to complete its review of the application.
The efficacy of palbociclib was demonstrated in 165 postmenopausal women with ER-positive, HER2-negative advanced breast cancer who had not received previous treatment for advanced disease. The participants were randomly assigned to receive either palbociclib in combination with letrozole or letrozole alone. The participants treated with palbociclib plus letrozole lived approximately 20.2 months without disease progression (progression-free survival) compared with approximately 10.2 months in participants receiving only letrozole. Information on overall survival is not available.
The most common side effects of treatment with palbociclib included neutropenia, leukopenia, fatigue, anemia, upper respiratory-tract infection, nausea, stomatitis, alopecia, diarrhea, thrombocytopenia, decreased appetite, vomiting, asthenia, peripheral neuropathy, and epistaxis.
It is recommended that treatment begin with a 125-mg dose for 21 days, followed by 7 days without treatment. Health care professionals are advised to monitor the complete blood count before the start of therapy and at the beginning of each cycle, as well as on day 14 of the first two cycles, and as clinically indicated.
Source: FDA; February 3, 2015.