Alliance Foundation Trials phase III PATINA study shows promise for patients with HR+, HER2+ metastatic breast cancer

(Press-News.org) Alliance Foundation Trials, LLC (AFT) and Pfizer Inc. today announced results from the phase III PATINA trial demonstrating that the addition of palbociclib (IBRANCE®) to current standard-of-care first-line maintenance therapy (following induction chemotherapy) resulted in statistically significant and clinically meaningful improvement in progression-free survival (PFS) by investigator assessment in patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-positive (HER2+) metastatic breast cancer (MBC). In the study, which is sponsored by AFT, median PFS was 44.3 months (95% CI: 32.4-60.9) for patients treated with palbociclib in combination with anti-HER2 therapy (trastuzumab or trastuzumab plus pertuzumab) and endocrine therapy and 29.1 months (95% CI: 23.3-38.6) for patients treated with anti-HER2 therapy and endocrine therapy alone [HR: 0.74 (95% CI, 0.58-0.94; unstratified 1-sided p= 0.0074]. This represents an extension in median PFS of more than 15 months. Overall survival, a secondary endpoint, was not yet mature at the time of the analysis. These results are being presented during a late-breaking oral session (Abstract GS2-12) and highlighted in the press program at the 47th San Antonio Breast Cancer Symposium (SABCS) in San Antonio, Texas.

 “PATINA is the first large phase III study to show the benefit of CDK4/6 inhibition in HR-positive, HER2-positive metastatic breast cancer,” said Otto Metzger, MD, Principal Investigator of the trial for Alliance Foundation Trials and Medical Oncologist at the Dana-Farber Cancer Institute. “These results support the potential of this maintenance treatment to slow disease progression and improve clinical outcomes in this patient population.”

Approximately 10% of all breast cancers are HR+, HER2+ [1], 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 common, and novel therapeutic approaches are needed for HR+, HER2+ MBC.[2] Palbociclib is not currently indicated for HR+, HER2+ MBC.

“IBRANCE, the first CDK4/6 inhibitor, revolutionized the treatment of HR-positive, HER2-negative metastatic breast cancer, and has been prescribed to over 773,000 patients since its initial approval in 2015," said Roger Dansey, MD, Chief Development Officer, Oncology, Pfizer. "These results demonstrate that the addition of IBRANCE to standard of care shows promise as maintenance therapy in HR-positive, HER2-positive disease. This trial underscores Pfizer’s leadership in addressing the needs of people with breast cancer, and we look forward to discussing the results with regulatory authorities.”

The safety and tolerability of palbociclib in the PATINA study was consistent with its known safety profile in HR+, HER2- MBC, and no new safety signals were identified. The most common adverse events observed with palbociclib were hematologic toxicities, such as neutropenia and leukopenia. Non-hematologic adverse events included fatigue, stomatitis, and diarrhea, which were generally mild to moderate in severity.

Since its initial regulatory approval in 2015, palbociclib continues to be a standard of care first-line treatment for HR+, HER2- MBC and has been approved in more than 108 countries. Pfizer plans to share the results from PATINA with regulatory authorities.

About the PATINA Trial
PATINA (AFT-38) is a randomized, open-label phase III study to evaluate the efficacy and safety of palbociclib (IBRANCE®) in combination with anti-HER2 therapy and endocrine therapy compared to anti-HER2 therapy and endocrine therapy alone as a first-line maintenance therapy (following induction chemotherapy treatment) for patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-positive (HER2+) metastatic breast cancer (MBC). While Pfizer is providing funding support for the trial, PATINA is sponsored by Alliance Foundation Trials, LLC (AFT) in collaboration with six international cancer research groups in the U.S., Germany, Italy, Spain, Australia, and New Zealand.

Study participants who were previously treated with anti-HER2 therapy were randomized to receive palbociclib, in addition to anti-HER2 therapy and endocrine therapy (n=261), or anti-HER2 therapy and endocrine therapy alone (n=257). The primary endpoint is progression-free survival (PFS) as assessed by the investigator. Overall survival is a secondary endpoint.  

[1] National Cancer Institute. Cancer Stat Facts: Female Breast Cancer Subtypes. https://seer.cancer.gov/statfacts/html/breast-subtypes.html#:~:text=Percent%20of%20Female,Unknown%20(6%25). Accessed December 2024.

[2] Nature. Estrogen/HER2 receptor crosstalk in breast cancer: combination therapies to improve outcomes for patients with hormone receptor-positive/HER2-positive breast cancer

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