FCGR2A and neoplasm: One of cetuximab's mechanisms of action is antibody‐dependent cellular cytotoxicity (ADCC).3, 4 ADCC is initiated when the antigen‐binding fragment (Fab) binds to the tumor cell and the crystallizable fragment (Fc) binds to the crystallizable fragment gamma receptor (FCGR) on a natural killer cell, macrophage, or monocyte, creating a bridge from the tumor cell to the effector cell.