Pfizer and Alliance Foundation Trials, LLC (AFT) recently unveiled findings from the Phase 3 PATINA trial, highlighting the potential of IBRANCE (palbociclib) in improving outcomes for patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-positive (HER2+) metastatic breast cancer (MBC). The results demonstrated that adding IBRANCE to the standard-of-care first-line maintenance therapy significantly extended progression-free survival (PFS), marking a notable advance in the treatment of this challenging condition.
The study evaluated IBRANCE in combination with anti-HER2 therapy (trastuzumab or trastuzumab plus pertuzumab) and endocrine therapy compared to anti-HER2 therapy and endocrine therapy alone. Median PFS for the IBRANCE-treated group was 44.3 months (95% CI: 32.4-60.9) versus 29.1 months (95% CI: 23.3-38.6) for the control group. This represents an improvement of over 15 months [HR: 0.74 (95% CI: 0.58-0.94); unstratified 1-sided p=0.0074]. While overall survival (a secondary endpoint) was not mature at the time of analysis, these promising results were presented at a late-breaking oral session (Abstract GS2-12) during the 47th San Antonio Breast Cancer Symposium (SABCS) in San Antonio, Texas.
Dr. Otto Metzger, principal investigator of the trial for Alliance Foundation Trials and a medical oncologist at Dana-Farber Cancer Institute, emphasized the significance of the findings. “PATINA is the first large Phase 3 study to show the benefit of CDK4/6 inhibition in HR-positive, HER2-positive metastatic breast cancer. These results support the potential of this maintenance treatment to slow disease progression and improve clinical outcomes in this patient population,” he said.
HR+, HER2+ breast cancer, often referred to as double-positive or triple-positive breast cancer, accounts for approximately 10% of all breast cancers. Despite advancements in treatment, resistance to anti-HER2 and endocrine therapy remains a significant challenge for patients with HR+, HER2+ MBC. The PATINA study offers hope for a novel therapeutic approach. However, it is worth noting that IBRANCE is not currently indicated for HR+, HER2+ MBC.
IBRANCE has been a cornerstone in the treatment of HR+, HER2-negative (HER2-) MBC since its regulatory approval in 2015. “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,” said Dr. Roger Dansey, 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. PATINA underscores Pfizer’s ongoing commitment to addressing the unmet needs of people with breast cancer, and we look forward to discussing the results with regulatory authorities.”
The safety profile of IBRANCE in the PATINA study was consistent with its established safety profile in HR+, HER2- MBC, with no new safety signals identified. The most common adverse events included hematologic toxicities such as neutropenia and leukopenia. Non-hematologic side effects such as fatigue, stomatitis, and diarrhea were generally mild to moderate in severity.
Since its introduction to the market, IBRANCE has been approved in more than 108 countries and continues to set the standard for first-line treatment of HR+, HER2- MBC. With the results of the PATINA trial, Pfizer aims to broaden the therapeutic applications of IBRANCE and plans to share these findings with regulatory authorities to explore potential new indications.
The PATINA study’s findings underline the ongoing evolution in breast cancer care, particularly for patients with HR+, HER2+ MBC. This trial marks an important milestone, offering a potential new treatment strategy that could extend progression-free survival and improve quality of life for many patients. The results also emphasize the importance of combining targeted therapies with endocrine treatment to address resistance mechanisms and enhance clinical outcomes.
While the overall survival data is still awaited, the extension in median PFS seen with the addition of IBRANCE represents a meaningful improvement in managing HR+, HER2+ MBC. These advancements not only reinforce Pfizer’s leadership in oncology but also highlight the broader potential of CDK4/6 inhibitors in addressing diverse breast cancer subtypes.
As the findings from the PATINA study are shared with the medical community and regulatory agencies, they offer renewed hope for patients battling HR+, HER2+ metastatic breast cancer. With continued research and collaboration, the future of breast cancer treatment appears increasingly promising, paving the way for enhanced patient outcomes and survival rates.
