FCGR3A and neoplasm: The main trastuzumab mechanism for attacking the tumor cells is to trigger the host immune system through a receptor the Fc portion of immunoglobulin G, which is encoded by the FCGR3A gene, and it is involved in the removal of antigen-antibody complexes from the circulation, as well as other responses, including antibody-dependent cellular cytotoxicity (ADCC)10.