Intratumoral Injection of an Adriamycin Immunoconjugate against Human Pancreatic Cancer Xenografts

We have evaluated the effect of an adriamycin conjugate of monoclonal antibody Nd2 (ADM‐Nd2) on the growth rate of SW1990 xenografts grown subcutaneously in athymic nude mice. Intravenous or intraperitoneal administration of radiolabeled Nd2 resulted in a maximum tumor accumulation of approximately 45% of the initial dose/g of tumor 3‐7 days after administration. However, administration into the tumor produced retention of 1200%ID/g 1 day after, with 50% of this high value remaining even at 7 days after administration. In contrast, intratumoral administration of a nonspecific immunoglobulin showed a lower initial retention and rapid loss of label. Both intravenously and intratumorally administered ADM‐Nd2 reduced the growth rate of SW1990 xenografts. While a single intravenous administration arrested growth for about two weeks, a single intratumoral injection prevented any increase in tumor size even 45 days after administration. Xenografts treated with ADM‐Nd2 showed degenerative changes at the histological level. Neither Nd2 alone nor Adriamycin alone inhibited growth when administered at the same dose as the conjugate.