January 28, 2026 — Alliance Foundation Trials, LLC (AFT) today announced the publication of the pivotal phase III PATINA study (AFT-38) in the New England Journal of Medicine (NEJM), marking a major milestone for patients with hormone receptor–positive (HR+), human epidermal growth factor receptor 2–positive (HER2+) advanced breast cancer (ABC). The study's results demonstrate that the addition of the CDK4/6 inhibitor palbociclib to standard first-line maintenance therapy significantly prolongs progression-free survival (PFS) by more than 15 months compared with standard therapy alone.
"This publication in the New England Journal of Medicine underscores the importance of these findings for the global breast cancer community," said Otto Metzger, MD, Principal Investigator of PATINA and Associate Medical Director of International Strategic Initiatives at Dana-Farber Cancer Institute. "The ability to meaningfully extend progression-free survival with a well-tolerated regimen offers new hope for individuals living with this challenging subtype of advanced breast cancer."
The publication highlights PATINA as the first large, randomized phase III study to demonstrate a clinical benefit for CDK4/6 inhibition in HR+, HER2+ advanced disease—representing a potential new maintenance-therapy approach for this patient population.
The PATINA study evaluated whether adding palbociclib to anti-HER2 therapy and endocrine therapy after four to eight cycles of induction chemotherapy could delay disease progression. The study found that patients receiving palbociclib experienced a meaningful improvement in median PFS, with no new signals.
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 who had no prior treatment in the advanced setting beyond induction were randomly assigned to receive either palbociclib with anti-HER2 and endocrine therapy (n=261) or anti-HER2 and endocrine therapy alone (n=257). Findings originally presented during a late-breaking oral session (Abstract GS2-12) at the 47th San Antonio Breast Cancer Symposium (SABCS) in December 2024 demonstrated an extension of progression-free survival (PFS) of more than 15 months (median PFS increased from 29.1 to 44.3 months) with the addition of palbociclib to anti-HER2 and endocrine therapy in this patient population.
"The mature and robust follow-up, combined with an up-to-date centralized clinical database for this international trial, enabled a timely final PFS analysis that demonstrated a statistically significant and clinically meaningful improvement in PFS," noted Sumithra Mandrekar, PhD, Group Statistician for AFT and lead statistician for PATINA.
Approximately 10% of all breast cancers are HR+, HER2+, sometimes referred to as double-positive or triple-positive breast cancer. Despite treatment advances, resistance to anti-HER2 and endocrine therapy remains a challenge, underscoring the need for new therapeutic strategies. Palbociclib is not currently indicated for HR+, HER2+ ABC.
Safety and tolerability findings in the PATINA study were consistent with the known safety profile of palbociclib in HR+, HER2-negative ABC, with no new safety signals identified.
The AFT-38 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.
