Fc region of cetuximab

The Fc (fragment crystallizable) region of cetuximab is the constant domain of the chimeric IgG1 monoclonal antibody used primarily in the treatment of metastatic colorectal cancer and head and neck squamous cell carcinoma. While the Fab regions of cetuximab are responsible for binding to the Epidermal Growth Factor Receptor (EGFR) to inhibit oncogenic signaling, the Fc region is essential for recruiting the host's immune system to the tumor site (FDA Label, Erbitux). It interacts with Fc gamma receptors (FcγRs) on effector cells, such as natural killer (NK) cells, to trigger antibody-dependent cellular cytotoxicity (ADCC), which significantly contributes to the drug's clinical efficacy (Vincenzi et al., 2011). Furthermore, the Fc region's interaction with the neonatal Fc receptor (FcRn) regulates the antibody's pharmacokinetic profile by enabling its recycling and preventing rapid clearance (Roopenian & Akilesh, 2007). Although the Fc region is a structural component of the therapeutic agent rather than a biological target itself, its glycosylation patterns and structural integrity are critical for maintaining the drug's therapeutic index and safety. Notably, while cetuximab is known for alpha-gal-mediated hypersensitivity, this specific carbohydrate moiety is located on the Fab portion rather than the Fc region (Chung et al., 2008).

Other names

Cetuximab Fc fragmentIgG1 Fc domain (cetuximab)Constant region of cetuximab

The Fc region of cetuximab facilitates immune-mediated tumor cell killing through Antibody-Dependent Cellular Cytotoxicity (ADCC) by binding to FcγRIIIa (CD16) on Natural Killer (NK) cells and macrophages (Vincenzi et al., 2011). It also binds to the neonatal Fc receptor (FcRn) to protect the antibody from lysosomal degradation, thereby extending its circulatory half-life (Roopenian & Akilesh, 2007).