Top Line: The CDK4/6-axis cross-talks with both estrogen-receptor and HER2-signaling and is a key pathway of resistance to respective targeted therapies.
The Study: The phase 3 PATINA trial included 518 patients with HR+/HER2+ metastatic breast cancer who did not progress after first-line induction chemo plus anti-HER2 therapy (mostly trastuzumab/pertuzumab) x 4-8 cycles. They all received standard maintenance anti-HER2 and endocrine therapy and were randomized to +/- the addition of palbociclib. As hoped, the addition of palbo significantly improved progression-free survival from 29 to 44 months (HR 0.75) translating to more than 4 years of total first-line disease control when induction is included. The trade-off is more grade 3+ events, namely neutropenia which was experienced by over half of women receiving palbo.
TBL: First-line triple-pathway blockade (ER, HER2, CDK4/6) for metastatic ER+ HER2+ breast cancer meaningfully extends progression-free survival at the cost of high rates of neutropenia. | Metzger, N Engl J Med 2026
The Study: The phase 3 PATINA trial included 518 patients with HR+/HER2+ metastatic breast cancer who did not progress after first-line induction chemo plus anti-HER2 therapy (mostly trastuzumab/pertuzumab) x 4-8 cycles. They all received standard maintenance anti-HER2 and endocrine therapy and were randomized to +/- the addition of palbociclib. As hoped, the addition of palbo significantly improved progression-free survival from 29 to 44 months (HR 0.75) translating to more than 4 years of total first-line disease control when induction is included. The trade-off is more grade 3+ events, namely neutropenia which was experienced by over half of women receiving palbo.
TBL: First-line triple-pathway blockade (ER, HER2, CDK4/6) for metastatic ER+ HER2+ breast cancer meaningfully extends progression-free survival at the cost of high rates of neutropenia. | Metzger, N Engl J Med 2026