Selective immunotherapy of small cell cancer xenografts using 131I-labelled SWA11 antibody

Intact SWA11 antibody was evaluated as a potential radioimmunotherapeutic agent against small cell lung cancer xenografts in a nude mouse model system. 131I-labelled SWA11 was given either in a single injection regimen (1 x 300 microCi) or as a multiple injection regimen achieving a total of 900 microCi (3 x 300 microCi with a 2 week interval between injections). Treatment of both small (mean volume approximately 0.2 cm3) and large (mean volume approximately 1.0 cm3) established xenografts resulted in significant anti-tumour effects and, in the case of the fractionated protocol, the failure of the xenografts to regrow within the period of observation (84 days). Xenograft histology following radioimmunotherapy showed large areas of necrosis, fibrosis and very few residual cells of SCLC origin.