PRETARGETED TUMOR IMAGING WITH STREPTAVIDIN IMMUNOCONJUGATES OF MONOCLONAL-ANTIBODY CC49 AND IN-111-DTPA-BIOCYTIN

Pretargeted tumour imaging was performed in nude mice bearing subcutan eous LS174T human colon cancer xenografts with streptavidin-CC49 monoc lonal antibody and In-111 DTPA biocytin. Mice were administered 250 mu g of streptavidin-CC49, followed 6 or 9 days later by 40 ng (250 mu C i) of In-111-DTPA-biocytin. Tumors were visualized at 24 h postinjecti on of In-111-DTPA-biocytin. Tumour uptake was 0.9-2.5% injected dose/g with tumour/nontarget ratios from 2:1 to 37:1 (except for kidney, whi ch was 0.5-3:1). Tumour uptake in mice pretargeted with streptavidin o r streptavidin-conjugated nonspecific nor mal mouse IgG was < 0.1% i.d ./g.