Despite the advancment in techniques to address metastatic breast cancer, there are still very few effective treatment options. A recent phase 3 trial showed that palbociclib doubled the time to cancer recurrence in those suffering with hormone-receptor (HR+) positive metastatic breast cancer. The data was published in the New England Journal of Medicine journal and presented at the 2015 annual American Society of Clinical Oncology (ASCO).

“These are women with advanced metastatic cancer whose disease was kept in check without the use of toxic and life-disrupting chemotherapy. This is a major advance for this population of women for which we had very few active options and are often treated with chemotherapy alone,” noted Massimo Cristofanilli, study’s senior author and the Director of the Breast Care Center at Thomas Jefferson University.

The PALOMA-3 study enrolled a total of 521 pre-/peri- and post-menopausal women with hormone receptor positive (HR+) and human epidermal growth factor receptor-negative (HER2-) advanced disease. These patients were not candidates for the HER2-blocking therapy herceptin since they had already relapsed on hormone therapy and were randomly assigned either palbociclib combined with fulvestrant, a drug that blocks the hormone receptor, or a placebo and fulvestrant.

The study’s primary endpoint was improvement in time to cancer relapse or progression-free survival. Those taking palbociclib together with fulvestrant evidenced a median progression-free survival of 9.2 months versus 3.8 months in the placebo group. Recurrence or cancer progression occurred in only 25 percent of those treated with palbociclib plus fulvestrant versus 50 percent for the placebo group.

Palbociclib was approved last February by the Food and Drug Administration (FDA) based on the PALOMA-1 trial, a phase 2 trial that assessed post-menopausal women who proved that palbociclib with letrozole, an estrogen-production blocker, doubled the recurrence time for metastatic cancer, evidencing a clear benefit for women suffering with advanced stages of the disease.

“Part of what was exciting about the design of this clinical trial is that we decided early on to accept women from a younger and generally sicker population than is typically enrolled in clinical trials. The PALOMA-3 study showed that palbociclib extends the time to progression of disease while maintaining very good quality of life,” said Cristofanilli from the Thomas Jefferson University.

Mace Rothenberg from Pfizer Oncology added: “Pfizer extends our deepest thanks to the investigators of the PALOMA-3 study for their efforts in leading a successful trial, and most importantly, the more than 500 women for their participation. Patients with HR+, HER2- metastatic breast cancer whose disease have progressed after endocrine therapy have significant unmet needs, and we’re pleased with the results of this study that demonstrate the potential for palbociclib as an important treatment option for this patient population.”