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FDA Grants Priority Review for Breast Cancer Drug Palbociclib
A new drug application (NDA) for palbociclib (Pfizer) has been accepted for filing and granted “priority review” status by the FDA. The NDA requests approval of the drug, in combination with letrozole, as a first-line treatment for postmenopausal women with estrogen receptor- positive (ER+), human epidermal growth factor receptor 2-negative (HER2–) advanced breast cancer who have not received previous systemic treatment for their advanced disease.
The submission was based on results from the randomized, phase II PALOMA-1 trial, which compared palbociclib plus letrozole with letrozole alone in postmenopausal women with ER+, HER– advanced breast cancer.
The FDA’s “priority review” status accelerates the review time from 10 months to a goal of 6 months from the day of the acceptance of filing and is given to drugs that may offer major advances in treatment or may provide a treatment where no adequate therapy exists. The Prescription Drug User Fee Act (PDUFA) goal date for a decision by the FDA is April 13, 2015. Palbociclib received a “breakthrough therapy” designation from the FDA in April 2013, for the first-line systemic treatment of women with advanced or metastatic ER+, HER2– breast cancer.
The PALOMA-1 trial was designed to assess progression-free survival in post-menopausal women with ER+, HER2– advanced breast cancer receiving palbociclib (125 mg once daily for 3 out of 4 weeks in repeated cycles) in combination with letrozole versus letrozole alone (2.5 mg once daily on a continuous regimen). Final results from the study were presented at the American Association for Cancer Research (AACR) Annual Meeting 2014.
Palbociclib is an investigational oral, targeted agent that selectively inhibits cyclin-dependent kinases (CDKs) 4 and 6 to regain cell-cycle control and to block tumor cell proliferation.
Loss of cell-cycle control is a hallmark of cancer. CDK 4 and 6 are over-activated in numerous cancers, leading to the loss of proliferative control. CDK 4/6 are key regulators of the cell cycle that trigger cellular progression from the growth phase (G1) into phases associated with DNA replication (S). CDK 4/6, whose activity is frequently increased in ER+ breast cancer, are key downstream targets of ER signaling in ER+ breast cancer. Preclinical data suggest that dual inhibition of CDK 4/6 and ER signaling is synergistic, and this activity has been shown to stop the growth of ER+ breast cancer cell lines in the G1 phase.
Source: Pfizer; October 13, 2014.