The addition of the CDK4/6 inhibitor palbociclib to standard maintenance therapy significantly improved progression-free survival in patients with hormone receptor (HR)-positive, HER2-positive metastatic breast cancer, according to results from the phase III PATINA trial published in JAMA Oncology.
Although CDK4/6 inhibitors are widely used in HR-positive, HER2-negative breast cancer, their role in HR-positive, HER2-positive disease has remained uncertain. The PATINA trial evaluated whether adding palbociclib to standard anti-HER2 and endocrine therapy could improve outcomes following induction chemotherapy.
CLINICAL SUMMARY
What was examined
The phase III PATINA trial evaluated the addition of palbociclib to maintenance anti-HER2 therapy and endocrine therapy in patients with HR-positive, HER2-positive metastatic breast cancer following induction chemotherapy.
Key findings
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The addition of palbociclib significantly improved progression-free survival compared with standard maintenance therapy.
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Median progression-free survival was approximately 44 months with palbociclib versus about 29 months with standard therapy.
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The safety profile was consistent with previous studies of CDK4/6 inhibitors.
Clinical implications
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CDK4/6 inhibition may represent a new treatment option in HR-positive, HER2-positive metastatic breast cancer
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Maintenance palbociclib may extend disease control following first-line therapy.y
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Updated clinical guidelines may be needed if these findings are incorporated into practice.
In this international, randomised phase III trial, patients with previously untreated HR-positive, HER2-positive metastatic breast cancer received induction chemotherapy in combination with anti-HER2 therapy. Patients without disease progression were then randomised to receive maintenance endocrine therapy and anti-HER2 therapy with or without palbociclib.
The addition of palbociclib significantly improved progression-free survival compared with standard maintenance therapy alone. Median progression-free survival was approximately 44 months in the palbociclib group compared with around 29 months in the control group, representing a clinically meaningful extension of disease control.
Featured Event
The safety profile was consistent with previous studies of CDK4/6 inhibitors. Neutropenia was more common in patients receiving palbociclib, but treatment was generally manageable with dose modifications and supportive care.
The results suggest that CDK4/6 inhibition may represent a new treatment option for patients with HR-positive, HER2-positive metastatic breast cancer receiving first-line therapy. If adopted into clinical practice, this approach could expand the role of CDK4/6 inhibitors beyond HER2-negative disease.
Paper: Wortelboer Nvan Ommen-Nijhof AKonings IR, et al. Overall Survival With First-Line vs Second-Line CDK4/6 Inhibitor Use in Advanced Breast Cancer: A Randomized Clinical Trial. JAMA Oncol. Published online February 19, 2026. Access online here.
