Pfizer Inc. (NYSE:PFE) today announced that the randomized Phase 2 trial [PALOMA-1] of palbociclib achieved its primary endpoint by demonstrating a statistically significant and clinically meaningful improvement in progression-free survival (PFS) for the combination of palbociclib and letrozole compared with letrozole alone in post-menopausal women with estrogen receptor positive (ER+), human epidermal growth factor receptor 2 negative (HER2-) locally advanced or newly diagnosed metastatic breast cancer. “We are delighted with the final data, which suggest the potential for palbociclib to transform the standard of care for post-menopausal women with ER+ and HER2- advanced breast cancer. This is encouraging information for these women, who represent approximately 60 percent of the advanced breast cancer population,” said Dr. Mace Rothenberg, senior vice president of Clinical Development and Medical Affairs and chief medical officer for Pfizer Oncology. “We will discuss these results with the FDA and other regulatory authorities to determine next steps, with the goal of bringing a much-needed new medicine to patients.” Adverse events observed for the palbociclib arm were consistent with the known adverse event profile for this combination. Detailed efficacy and safety data from PALOMA-1 will be submitted for presentation at the American Association for Cancer Research (AACR) Annual Meeting 2014 scheduled for April 5-9 th in San Diego. Palbociclib received Breakthrough Therapy designation by the United States Food and Drug Administration (FDA) in April 2013, for the initial treatment of women with advanced or metastatic ER+, HER2- breast cancer. This designation was based on interim data from the PALOMA-1 trial. A randomized, global Phase 3 trial (PALOMA-2) in this patient population is currently enrolling patients. About PALOMA-1 PALOMA-1 (also known as Study 1003) is a Phase 2 trial designed to assess the PFS of palbociclib (125 mg once daily for three out of four weeks in repeated cycles) in combination with letrozole versus letrozole alone (2.5 mg once daily on a continuous regimen) in post-menopausal women with ER+, HER2- advanced breast cancer. PFS is comprised of time from randomization to time of disease progression or death from any cause. PALOMA-1 was conducted in collaboration with the Jonsson Cancer Center’s Revlon/UCLA Women’s Cancer Research Program. PALOMA-1 is a multi-center trial with 101 global sites participating.