cetuximab + bevacizumab

The combination of cetuximab and bevacizumab is a dual monoclonal antibody therapy that targets both epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) pathways. This combination has been studied primarily in metastatic colorectal cancer (mCRC) and squamous cell carcinoma of the head and neck (SCCHN). ## Mechanism of Action Cetuximab is a chimeric monoclonal antibody that binds specifically to the extracellular domain of EGFR, preventing receptor activation and downstream signaling pathways involved in cell proliferation, survival, and angiogenesis[5][8]. It promotes EGFR degradation, inhibits phosphorylation, and ultimately leads to inhibition of cell cycle progression and induction of apoptosis[5][6]. Bevacizumab is a humanized monoclonal antibody that binds to VEGF-A, preventing its interaction with VEGF receptors[8]. This disrupts angiogenesis by inhibiting new vessel formation and causing regression of existing tumor vasculature[8]. The combination targets two critical pathways in cancer development and progression, potentially offering synergistic effects. Preclinical data suggest that VEGF signaling is upregulated by EGFR expression, while VEGF upregulation has been associated with resistance to cetuximab[6].