Selective accumulation of a new antineoplastic agent, K-18 (human immunoglobulin conjugated melphalan), in Ehrlich carcinoma transplanted in mice

The absorption of K-18 (human IgG conjugated melphalan) through the intestine and its selective accumulation in the tumor were studied. After oral administration of 14C-melphalan and 14C-K-18 to ICR mice with subcutaneously transplanted Ehrlich carcinoma, K-18 was detected at the tumor site by autoradiogram after 48 hrs, but melphalan was not. Immunofluorescence study showed that orally administered K-18 was absorbed from the intestine via both the portal and the lymphatic route. Moreover, immunoperoxidase staining revealed K-18 in cytoplasm of tumor cells, but not in bone marrow cells. These results demonstrate the absorption of K-18 from the intestine after oral administration and its selective affinity for tumor tissue.