Progression-free survival was significantly and consistently improved when palbociclib was added to fulvestrant, compared with placebo and fulvestrant, for women with stage IV breast cancer that is hormone-receptor-positive and HER2-negative. This phase 3 study included women whose disease was resistant to standard endocrine therapy.1
“This is a significant achievement because patients who fail to respond to endocrine therapy usually require chemotherapy for treatment with a compromise on quality of life,” said Massimo Cristofanilli, MD, professor of medicine at Northwestern University Feinberg School of Medicine and a Northwestern Medicine oncologist in Chicago, Illinois, and first author of the study. “The current study provides an effective and less toxic option for the most common type of metastatic breast cancer.”
“The patients in this study who received the combination treatment experienced a better quality of life than those who received the standard endocrine therapy. The study also included patients who received chemotherapy,” said Cristofanilli, who is also the associate director for precision medicine and translational research at the Robert H. Lurie Comprehensive Cancer Center of Northwestern. This treatment, he said, also comes without the typical side effects of chemotherapy, which may include complete hair loss and neuropathy.
Estrogen can sometimes fuel breast cancer. Endocrine therapy works to block the estrogen, and this study focused on women who may have been previously resistant to endocrine treatment. This study was also the first test of this drug combination in premenopausal women, a patient population with very limited treatment options.
The study enrolled 521 women from 144 centers across 17 countries, age 18 years and older, who had endocrine-resistant, hormone receptor-positive metastatic breast cancer. Over the 10-month, phase 3 clinical trial between 2013 and 2014, patients were randomly assigned to receive 2 drugs, palbociclib and fulvestrant, or a placebo and fulvestrant.
Patients who received the combined-drug treatment experienced, on average, 9.5 months of progression-free survival compared with 4.6 months for the control group, a difference of 4.9 months.
“For women living with breast cancer, prolonged disease control may translate into improved survival, and this is as close as we can get to a cure,” Cristofanilli said. “For now, we are hoping to get to the point where breast cancer is a chronic disease that we can continue to treat for a long time, and this drug gives an important additional option for women with estrogen-positive metastatic breast cancer.”
1. Cristofanilli M, Turner NC, Bondarenko I, et al. Fulvestrant plus palbociclib versus fulvestrant plus placebo for treatment of hormone-receptor-positive, HER2-negative metastatic breast cancer that progressed on previous endocrine therapy (PALOMA-3): final analysis of the multicentre, double-blind, phase 3 randomised controlled trial [published online ahead of print March 2,2016]. The Lancet Oncol. doi:10.1016/S1470-2045(15)00613-0.