FDA approves new therapy for double-positive metastatic breast cancer

The U.S. Food and Drug Administration (FDA) has approved a new therapy regimen for patients with "double-positive" metastatic breast cancer based on results of the phase 3 PATINA study led by Otto Metzger, MD, Associate Medical Director of International Strategic Initiatives at Dana-Farber Cancer Institute. The PATINA trial demonstrated that the addition of the CDK 4/6 inhibitor palbociclib to standard therapy in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-positive (HER2+) metastatic breast cancer resulted in a more than 15-month improvement in progression-free survival. The findings were reported in the New England Journal of Medicine and also presented at the San Antonio Breast Cancer Symposium in December 2024.

"Resistance to dual anti-HER2 and endocrine therapy remains a central clinical challenge for patients with HR+, HER2+ metastatic breast cancer – even after an excellent response to initial treatment," said Metzger. "Based on the results from the PATINA study, the addition of palbociclib in the maintenance phase can meaningfully extend the time patients go without their disease progressing. This approval gives oncologists a new, evidence-based option to optimize maintenance therapy for their patients with HR+, HER2+ disease."

Approximately 10% of all breast cancers are HR+, HER2+, which is sometimes referred to as double-positive or triple-positive breast cancer. Despite advances in treatment, the development of resistance to anti-HER2 and endocrine therapy is a challenge, and novel therapeutic approaches are needed for HR+, HER2+ metastatic breast cancer.

In the PATINA study, participants with metastatic disease who were previously treated with anti-HER2 therapy were randomized to receive palbociclib, in addition to anti-HER2 therapy and endocrine therapy, or anti-HER2 therapy and endocrine therapy alone. The primary endpoint was progression-free survival as assessed by the investigator. The median progression free survival was 44.3 months for patients treated with palbociclib in combination with anti-HER2 therapy (trastuzumab or trastuzumab plus pertuzumab) and endocrine therapy, and 29.1 months for patients treated with anti-HER2 therapy and endocrine therapy alone, representing an extension in median PFS of over 15 months. 

PATINA was sponsored by Alliance Foundation Trials, LLC (AFT) in collaboration with six international cancer research groups in the U.S., France, Germany, Italy, Spain, Australia, and New Zealand. Funding support was provided by Pfizer.