trastuzumab + pertuzumab + palbociclib + exemestane

This combination regimen consists of two HER2-targeted monoclonal antibodies (trastuzumab and pertuzumab), a CDK4/6 inhibitor (palbociclib), and a steroidal aromatase inhibitor (exemestane). It is being investigated as a chemotherapy-free neoadjuvant treatment for patients with triple-positive breast cancer (HER2-positive and hormone receptor-positive). Trastuzumab and pertuzumab work synergistically to inhibit HER2 signaling by binding to different extracellular domains of the receptor. Palbociclib arrests the cell cycle at the G1 phase by inhibiting CDK4 and CDK6, while exemestane reduces estrogen levels by irreversibly binding to the aromatase enzyme. The study is led by Anhui Provincial Cancer Hospital and utilizes biosimilars QL1701 (trastuzumab) and QL1209 (pertuzumab) developed by Qilu Pharmaceutical.