Specific immune response induced in mice by immunization with the human epidermal growth factor receptor extracellular domain

Epidermal Growth Factor Receptor (EGFR or HER1) is considered a tumor associated antigen. HER1 is overexpressed in many human epithelial tumors and involved in crucial cellular functions for tumor development. For this reason HER1 is considered a good target for cancer immunotherapy and some passive agents are being evaluated in clinical trials. However, HER1 -based active immunotherapy has not been clinically explored. To develop an active immunotherapy approach based on HER1 for the treatment of HER1 + cancer patients, we cloned and expressed in mammalian cells the HER1 extracellular domain protein (HER1 -ECD), which was specifically recognized by an anti EGFR monoclonal antibody. HER1 -ECD was purified by affinity chromatography and adjuvated in Very Small Size Proteoliposomes (VSSP) or Complete Freund adjuvant to immunize C57BL/6 mice. Immunization elicited specific humoral and cellular immune response. The polyclonal antibodies induced by immunization recognized the full length HER1 on the surface of a lung tumor cell line. These results suggest that HER1 -ECD could be an appropriated antigen to induce specific immune response in patients with HER1 + tumors.