Combination of Palbociclib with Letrozole significantly prolonging progression of tumor compared with single letrozole in post-menopausal women with estrogen receptor positive. This details resulted from PALOMA-1 study which is a Phase 2 trial designed to assess progression-free survival in post-menopausal women with ER+, HER2- advanced breast cancer receiving palbociclib in combination with letrozole versus letrozole alone.
The combination of palbociclib and letrozole was well-tolerated and the safety profile of the combination was consistent with previously reported data. The most common adverse events in the palbociclib plus letrozole arm were neutropenia, leukopenia, fatigue and anemia. The neutropenia observed with the combination in this study was non-cumulative and clinically manageable. No cases of febrile neutropenia were reported in either arm of the study. Neutropenia is an on-target, anti-proliferative side effect of palbociclib and signifies inhibition of CDK4 and its effect on bone marrow.
"These data demonstrate the potential of palbociclib to be a major advance in the treatment of women with this type of advanced breast cancer," said Dr. Mace Rothenberg, senior vice president of Clinical Development and Medical Affairs and chief medical officer for Pfizer Oncology. "We are proud to be at the forefront of research and development with respect to this promising new class of investigational anticancer agents and have initiated a broad clinical development program for palbociclib that includes breast and non-breast cancers.”
Palbociclib received Breakthrough Therapy designation from 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. Pfizer continues to work with the FDA and other regulatory authorities to define the appropriate regulatory path forward for palbociclib.
