Palbociclib & HER2+ Breast Cancer: Progression-Free Survival Boost

Palbociclib Significantly Extends Progression-Free Survival in Aggressive Breast Cancer, Landmark Study Shows

A new study published in the New England Journal of Medicine demonstrates that adding the drug palbociclib to standard treatment for a specific type of metastatic breast cancer can significantly delay disease progression. The findings offer hope for patients with hormone receptor-positive (HR+), human epidermal growth factor receptor 2-positive (HER2+) breast cancer, a particularly challenging form of the disease.

Breakthrough Findings from the PATINA Trial

The phase 3 PATINA study, involving 518 patients across multiple countries, revealed a median progression-free survival (PFS) of 44.3 months for those receiving palbociclib in combination with anti-HER2 and endocrine therapy, compared to 29.1 months for those receiving anti-HER2 and endocrine therapy alone. This represents a considerable improvement in disease control for patients who currently face an incurable diagnosis.

“These results show that adding palbociclib, a well-tolerated, oral agent, to our standard treatment regimen provides a substantial and meaningful prolongation of response time and disease control for these patients,” stated a senior investigator involved in the study.

Did you know? – HR+, HER2+ breast cancer, often called double-positive, accounts for roughly 10% of all breast cancer diagnoses. It tends to be more aggressive than other subtypes, requiring specialized treatment approaches.

A New Approach to Maintenance Therapy

The PATINA trial is the frist large, randomized phase 3 study to demonstrate a clinical benefit from CDK4/6 inhibition in HR+, HER2+ metastatic disease. This finding suggests a potential new maintenance therapy approach for this patient population, following initial treatment with chemotherapy. Approximately 10% of all breast cancers fall into the HR+, HER2+ category, often referred to as double-positive or triple-positive breast cancer. Current first-line treatment typically involves dual anti-HER2 therapy alongside chemotherapy, followed by maintenance HER2-targeted and endocrine therapy.

Overcoming Treatment Resistance

Despite advancements in treatment,resistance to both endocrine and anti-HER2 therapies remains a significant obstacle. Preclinical and early clinical data indicated that inhibiting CDK4/6 could potentially overcome this resistance, and the PATINA study now provides strong evidence supporting this hypothesis.

The trial, conducted between June 2017 and July 2021, enrolled patients from clinical sites in the U.S., Europe, New Zealand, and Australia. Participants were randomly assigned to receive either palbociclib alongside standard therapies (n=261) or standard therapies alone (n=257).

Collaborative Effort Drives Progress

The PATINA study was funded by Pfizer, Inc., and supported by a broad academic collaboration led by Alliance Foundation Trials, LLC. Partnering organizations included Breast Cancer Trials (Australia and New Zealand), Fondazione Michelangelo, GBG Forschungs GmbH, PrECOG, SOLTI, and Unicancer.

“The PATINA study exemplifies the power of global academic collaboration to answer clinically important questions that directly impact patient care,” said Peter J. O’Dwyer, MD, chief executive officer and chair of PrECOG.”We are proud to have partnered with international research groups to help advance a potential new standard for frontline maintenance therapy in this distinct subset of metastatic breast cancer.”

The full study findings are available in the New england Journal of medicine, published on https://www.nejm.org/doi/10.1056/NEJMoa2511218. The research, authored by Metzger, O.,et al. (2026), marks a significant step forward in the fight against this aggressive form of breast cancer.