The U.S. Food and Drug Administration said on Tuesday that is has approved the use of Pfizer's palbociclib oral capsules, in combination with letrozole, to treat advanced breast cancer.
The drug's label said it blocks cyclin-dependent kinases four and six, which cause cellular proliferation. Together, palbociclib and letrozole are believed to reduce the growth of tumors. The drug is meant for the treatment of estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer in women who are postmenopausal and have not received endocrine-based therapy.
A clinical trial of 165 postmenopausal women with ER-positive, HER2-negative metastatic breast cancer tested the efficacy of a combination of palbociclib and letrozole vs. letrozole and a placebo. On average, women given the combination of palbociclib and letrozole lived without disease progression for 20.2 month. Women treated with letrozole and a placebo went 10.2 months without disease progression. Currently, a clinical trial is being conducted to help determine whether palbociclib prolongs the lives of women with advanced breast cancer.
Pfizer markets palbociclib as IBRANCE, and it is now available through a specialty pharmacy network that also distributes other Pfizer cancer treatments.
“The registration trial showed that, compared to letrozole alone for first-line treatment of ER+/HER2- advanced breast cancer, IBRANCE in combination with letrozole almost doubled the time before tumor progression, delaying the need for later-line therapies including other hormonal agents and chemotherapies,” Pfizer Chairman and CEO Ian Read said.