Pfizer has received approval from the US Food and Drug Administration (FDA) for Ibrance (palbociclib) in combination with trastuzumab, with or without pertuzumab, and endocrine therapy as a maintenance treatment for adults with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-positive (HER2+) locally advanced or metastatic breast cancer following induction treatment.

The approval is based on findings from the Phase 3 PATINA trial, sponsored by the Alliance Foundation Trials (AFT), which demonstrated that adding Ibrance to anti-HER2 therapy and endocrine therapy reduced the risk of disease progression or death by 24 percent compared with anti-HER2 and endocrine therapy alone.

With this approval, Ibrance becomes the first and only CDK4/6 inhibitor indicated for patients with HR-positive metastatic breast cancer irrespective of HER2 status. The expanded indication is expected to provide a new maintenance treatment option for patients with HR+, HER2+ disease, a subtype that accounts for around 10 percent of all breast cancer cases and has historically had limited targeted treatment options.

Commenting on the approval, Aamir Malik, Chief US Commercial Officer and Executive Vice President at Pfizer, said Ibrance has played a transformative role in metastatic breast cancer treatment over the past decade by establishing CDK4/6 inhibition as a standard of care. He added that the latest approval extends the medicine's reach to patients with HR+, HER2+ metastatic breast cancer who continue to face treatment resistance, reinforcing Ibrance's role as a backbone therapy across combination treatment regimens.

The PATINA study evaluated Ibrance as a first-line maintenance therapy after induction treatment. Participants who completed a median of six cycles of induction therapy were randomised to receive either Ibrance alongside anti-HER2 and endocrine therapy or anti-HER2 and endocrine therapy alone. The trial's primary endpoint was progression-free survival, while overall survival remains a secondary endpoint and continues to be evaluated.

The safety profile observed in the study was consistent with the known safety profile of Ibrance. The most common adverse events included reductions in white blood cell and neutrophil counts, while non-haematologic side effects such as diarrhoea, infections, stomatitis and fatigue were generally mild to moderate in severity. Results from the PATINA trial were previously published in The New England Journal of Medicine and presented at the 2024 San Antonio Breast Cancer Symposium.

Dr. Otto Metzger, principal investigator for the PATINA trial at Alliance Foundation Trials and Medical Oncologist at the Dana-Farber Cancer Institute, said resistance to dual anti-HER2 and endocrine therapy remains a significant challenge for patients with HR+, HER2+ metastatic breast cancer. He noted that the addition of Ibrance during the maintenance phase can meaningfully extend the time patients live without disease progression, providing oncologists with a new evidence-based treatment option.

Initially approved in 2015, Ibrance has become a standard first-line treatment for HR+, HER2-negative metastatic breast cancer and has been prescribed to more than 900,000 patients across over 100 countries. The latest approval further expands its role in metastatic breast cancer treatment by bringing CDK4/6 inhibition to patients with HR+, HER2+ disease following induction therapy.