New Treatment Option for Hormone Receptor-positive Breast Cancer

Palcociclib combined with the existing standard drug prolongs the life of women with hormone receptor-positive metastatic breast cancer, reveals a new phase three clinical trial. ‘We now have solid data to suggest that this //treatment should be the new standard of care," said lead author Dr Massimo Cristofanilli, a professor of hematology/oncology at Northwestern University Feinberg School of Medicine and a Northwestern Medicine physician. The study was published in the New England Journal of Medicine.

The majority of breast cancers are classified as hormone receptor-positive (HR-positive). Patients with HR-positive breast cancer are typically treated with hormone therapy, which prevents estrogen from attaching to receptors and fueling cancer growth. But over time, many patients develop resistance to such treatment, and there is a significant need for new therapies for patients with advanced disease.

Palbociclib is a novel oral drug that inhibits enzymes important in cell division called cyclin-dependent kinase (CDK) 4/6. An international clinical trial called PALOMA-3 evaluated palbociclib in 521 women with HR-positive metastatic breast cancer who had relapsed or progressed after prior hormone therapy.

The trial participants were randomized to receive either palbociclib and fulvestrant (a standard treatment) or a placebo and fulvestrant.In a previous analysis of PALOMA-3 led by Cristofanilli and published in The Lancet Oncology, palbociclib and fulvestrant were found to be associated with a significant improvement in progression-free survival, compared to fulvestrant alone.

The findings led to FDA approval of palbociclib for patients with HR-positive, HER2-negative metastatic breast cancer who experienced disease progression following hormone therapy.The current study, published in the New England Journal of Medicine, reported overall survival outcomes for participants in PALOMA-3. It is the first to report overall survival data from a phase III trial testing a CDK4/6 inhibitor in this patient population, said Cristofanilli.

Investigators found palbociclib led to a clinically meaningful improvement in overall survival; median overall survival was 34.9 months in the palbociclib and fulvestrant group, compared to 28 months in the control group. The benefit was even greater in patients with sensitivity to prior hormone therapy.

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"Typically, treatments for estrogen-positive metastatic breast cancer delay the progression of cancer but almost never prolong the life of patients. This treatment is the first of its kind to show such an important benefit," Cristofanilli said.

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Source-Eurekalert