palbociclib + pertuzumab + trastuzumab

This is a combination regimen consisting of three targeted therapies used in the treatment of hormone receptor-positive (HR+), human epidermal growth factor receptor 2-positive (HER2+) metastatic breast cancer. Palbociclib is an oral small molecule inhibitor of cyclin-dependent kinases 4 and 6 (CDK4/6), which blocks cell cycle progression from G1 to S phase, thereby inhibiting tumor cell proliferation. Pertuzumab and trastuzumab are monoclonal antibodies that target different epitopes on the HER2 receptor, blocking HER2-mediated signaling and promoting antibody-dependent cellular cytotoxicity. The combination aims to synergistically inhibit both cell cycle progression and HER2-driven oncogenic signaling pathways, improving clinical outcomes for patients with HR+/HER2+ metastatic breast cancer[1][5][6].