Tumour localization of monoclonal antibody against a rat mammary carcinoma and suppression of tumour growth with adriamycin-antibody conjugates

Summary Monoclonal antibody to the rat mammary carcinoma Sp4 isolated from hybridoma supernatants and labelled with ¹²⁵I showed preferential in vivo localization into subcutaneous growths of Sp4 compared with normal tissues and a range of other transplanted tumours. No specific localization was seen with ¹²⁵I-labelled normal rat immunoglobulin. Adriamycin conjugated to monoclonal antibody significantly retarded Sp4 tumour growth at 1/25th of the effective dose of the free drug, and in some cases brought about total tumour regression. Normal rat immunoglobulin-adriamycin conjugates were relatively ineffective. These studies indicate that monoclonal antibody directed against tumour cell surface antigens may be highly effective for tumour targeting of therapeutic agents.