The US Food and Drug Administration (FDA) has approved palbociclib (Ibrance; Pfizer) for advanced (metastatic) breast cancer in postmenopausal women under its accelerated approval programme.
In a statement, Pfizer said it had been in discussions with European regulatory health authorities and intends to file an application with the European Medicines Agency for a marketing authorisation for palbociclib in the EU later in 2015.
Palbociclib inhibits cyclin-dependent kinases (CDKs) 4 and 6, which promote the growth of cancer cells. It is intended for 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, and is used in combination with letrozole. In a trial of 165 such women, progression-free survival was 20.2 months in women randomised to palbociclib plus letrozole, compared with 10.2 months in women who received letrozole alone.
The FDA granted palbociclib breakthrough therapy designation, because Pfizer showed the drug may offer a substantial improvement over available therapies, and it received priority review under the FDA’s accelerated programme. This programme allows approval of a drug for a serious or life-threatening disease based on data showing the drug has an effect on a surrogate endpoint reasonably likely to predict clinical benefit to patients, allowing patients earlier access to promising drugs while the company conducts confirmatory clinical trials. The FDA’s decision on palbociclib is two months ahead of schedule; the agency was scheduled to complete its review of the application by 13 April 2015.
Palbociclib’s most common side effects are neutropenia, leukopenia, fatigue, anaemia, upper respiratory infection, nausea and vomiting, stomatitis, hair loss, diarrhoea, low blood platelet counts, decreased appetite, peripheral neuropathy, and nosebleeds. The recommended starting dose is 125 milligram for 21 days, followed by a seven-day treatment break, with complete blood count monitoring at the start of every cycle and on day 14 of the first two cycles.