Induction of tumour cell lysis by a bispecific antibody recognising epidermal growth factor receptor (EGFR) and CD3.

A bispecific antibody construct (bAb) recognising CD3 and epidermal growth factor receptor (EGFR) was studied in vitro. Human peripheral blood lymphocytes (PBL), pre-activated with monoclonal antibody OKT-3 or with irradiated tumour cells, were armed with the bAb construct and targeted to autologous and allogeneic tumour target cells in culture. bAb EGFR x CD3 promoted significant cytolysis even at a concentration of 1 ng/ml. The specificity of target cell lysis was provided by the EGFR specificity of the bAb, as tumour cells negative for EGFR were not lysed. However, not only EGFR-positive tumour cells but also EGFR-positive normal cells were killed. Human renal cancer cell lines and the normal autologous kidney cell cultures expressing the same level of EGFR molecules were lysed to a similar extent. These results may contribute toward the planning of future clinical trials with such bAb.