Breast Cancer Drug Palbociclib Readied for FDA Submission
CDK inhibitor blocks tumor-cell proliferation
Pfizer has announced that it will submit a new drug application (NDA) to the FDA for palbociclib combined with letrozole as first-line systemic treatment in post-menopausal women with estrogen receptor (ER)-positive, human epidermal growth factor receptor 2 (HER2)-negative locally advanced or metastatic breast cancer.
The company expects to submit the NDA early in the third quarter of this year.
In April 2013, palbociclib received a “breakthrough therapy” designation from the FDA for first-line systemic treatment of women with advanced or metastatic ER-positive, HER2-negative breast cancer. This designation was based on interim data from the phase II, randomized PALOMA-1 trial, which evaluated palbociclib plus letrozole compared with letrozole alone in this population of patients.
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.
The loss of cell-cycle control is a hallmark of cancer, and CDKs 4 and 6 are over-activated in numerous cancers, leading to loss of proliferative control. CDKs 4 and 6 are key regulators of the cell cycle that trigger cellular progression from the growth phase (G1) into phases associated with DNA replication (S). Moreover, CDKs 4 and 6, whose activity is frequently increased in ER-positive breast cancer, are key downstream targets of ER signaling in ER-positive breast cancer.
The PALOMA-1 trial was designed to assess progression-free survival in post-menopausal women with ER-positive, HER2-negative advanced breast cancer receiving palbociclib (125 mg once daily for 3 out of 4 weeks in repeated cycles) in combination with letrozole compared with letrozole alone (2.5 mg once daily on a continuous regimen). Final results from this study were presented at the American Association for Cancer Research (AACR) Annual Meeting 2014, held April 5–9 in San Diego, California.
Source: Pfizer; May 16, 2014.