Experimental radioimmunotherapy of a xenografted human glioma using 131I-labeled monoclonal antibody to epidermal growth factor receptor.

Abstract

131I-labeled F(ab')2 fragments of murine monoclonal antibody (MAb) 425 specific to the epidermal growth factor receptor expressed on human gliomas were used in experimental human malignant glioma immunotherapy. Two injections of 150 microCi 131I-labeled 425 F(ab')2 achieved growth inhibition of U-87MG human malignant glioma xenografts in nude mice. This radiolabeled specific MAb F(ab')2 was significantly superior to radiolabeled fragments of an anti-hepatitis virus control MAb A5C3 in influencing tumor growth. However, similar treatment of established human malignant glioma xenografts did not inhibit progressive tumor growth significantly. No clear tumor inhibition was produced by unlabeled MAb 425 F(ab')2. These studies suggest that 131I-labeled MAbs have a significant antitumor effect where unmodified antibody is ineffective. Multiple doses of antibody may achieve an increase in labeled MAb concentration in tumors.