Radioimmunotherapy of DU-145 tumours in nude mice - A pilot study with E4,a novel monoclonal antibody against prostate cancer

The anti-rumour effect of the I-131-labelled antiprostate monoclonal antibo dy (MAb) E4 was studied in an experimental model with 41 nude mice, subcuta neously xenografted with a human prostate cancer cell line (DU-145). The mi ce were divided into four study groups, i.e. one receiving single and anoth er repeated injections of the radiolabelled MAb. A third group was injected with non-labelled MAb, and the fourth served as an untreated control group . The tumour volumes increased similarly in all groups during the 27-day ob servation period. The tumour tissue was morphologically disintegrated in th e group that received repeated radioimmunotherapy (RIT). The tumours from t his group contained large fluid-filled cystic parts and demonstrated pronou nced cellular and subcellular polymorphism in the remaining viable tumour t issue. The untreated control rumours and single therapy rumours remained so lid. The proportion of the total tumour volume that consisted of viable tum our cells, as determined by morphometric techniques, was significantly lowe r in the I-131-E4-treated groups. The use of I-131-labelled E4 MAb has thus demonstrated a promising therapeutic potential.