In summary, monoclonal antibodies directed at two of the class I growth factor receptors, EGFR and HER2, have shown to be active and well tolerated. These findings represent proof of concept that the use of monoclonal antibodies against growth factor receptors is a valid and promising approach in the therapy of patients with cancer. Current research goals include to define the optimal combinations with conventional chemotherapeutic agents and with radiation therapy, determine the best therapy candidates and to expand clinical trials to other tumour types.