Philadelphia, PA, January 29, 2026 — PrECOG, LLC, today announced the publication of final results from the pivotal phase 3 PATINA study in the New England Journal of Medicine (NEJM) . The study evaluated whether adding palbociclib to anti-HER2 and endocrine therapy, following induction chemotherapy, could delay disease progression in patients with hormone receptor–positive (HR+), human epidermal growth factor receptor 2–positive (HER2+) metastatic breast cancer. Results showed a median progression-free survival (PFS) of 44.3 months in the palbociclib arm, compared with 29.1 months in the control arm.
“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 who suffer from a currently incurable disease," said Angela M. DeMichele, MD, MSCE , PrECOG co-principal Investigator for PATINA and the Mariann T. and Robert J. MacDonald Professor in Breast Cancer Care Excellence at the University of Pennsylvania Perelman School of Medicine.
The NEJM publication establishes PATINA as the first large, randomized phase 3 study to demonstrate a clinical benefit for CDK4/6 inhibition in HR+, HER2+ metastatic disease. The finding suggests a potential new maintenance-therapy approach for this patient population.
Approximately 10% of all breast cancers are HR+, HER2+, sometimes referred to as double-positive or triple-positive breast cancer. Current standard first-line treatment consists of dual anti-HER2 therapy plus chemotherapy, followed by maintenance HER2-targeted and endocrine therapy.
Despite substantial advances in treatment, resistance to both endocrine and anti-HER2 targeted therapies remains a persistent clinical challenge. Preclinical and early clinical data suggested that CDK4/6 inhibition may help overcome resistance to these therapies.
From June 2017 through July 2021, the trial enrolled 518 patients across 109 clinical sites in the U.S., Europe, New Zealand, and Australia. Participants were randomly assigned to receive either palbociclib with anti-HER2 and endocrine therapy (n=261) or anti-HER2 and endocrine therapy alone (n=257).
The PATINA study was funded by Pfizer, Inc., and supported by an academic collaboration led by Alliance Foundation Trials, LLC, as the global sponsor, in partnership with 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.”
About PrECOG
PrECOG, LLC is a cancer research organization that designs and conducts innovative oncology studies through industry partnerships and research networks. The central focus of PrECOG is to conduct trials that align with the overall scientific mission and research goals of the ECOG-ACRIN Cancer Research Group. Visit www.precogllc.org and follow us on Twitter @PrECOGonc , Facebook , and LinkedIn .
Citation: Metzger O, Mandrekar S, Goel S, et al. Palbociclib for Hormone-Receptor–Positive, HER2-Positive Advanced Breast Cancer. New England Journal of Medicine . 2026;394(5):451-462. doi: https://doi.org/10.1056/nejmoa2511218
Official Study Title: A Randomized, Open Label, Phase III Trial to Evaluate the Efficacy and Safety of Palbociclib + Anti-HER2 Therapy + Endocrine Therapy vs. Anti-HER2 Therapy + Endocrine Therapy After Induction Treatment for Hormone Receptor Positive (HR+)/HER2-Positive Metastatic Breast Cancer.
A full description of the PATINA study (AFT-38, PrECOG PrE0111) is publicly available at https://clinicaltrials.gov/study/NCT02947685 :
New England Journal of Medicine
Palbociclib for Hormone-Receptor–Positive, HER2-Positive Advanced Breast Cancer
28-Jan-2026