Effective cancer targeting using an anti-tumor tissue vascular endothelium-specific monoclonal antibody (TES-23)

Immunoconjugate targeting of solid tumors has not been routinely successful because the endothelial cells of blood vessels act as a physical barrier a gainst the transport of macromolecules, such as antibodies. In the present study, we attempted to achieve tumor vascular targeting with an antitumor t issue endothelium-specific monoclonal antibody (TES-23). TES-23, an IgG1 mo noclonal antibody raised against rat KMT-17 fibrosarcoma-derived endothelia l cells, was covalently conjugated with neocarzinostatin (NCS) in a previou s study. The TES-23-NCS conjugate induced tumor hemorrhagic necrosis, and s howed marked anti-tumor effects against rat KMT-17 fibrosarcoma. This resul t prompted us to investigate whether this approach would be applicable to v arious other types of solid tumors. One hour after injection of I-125-label ed TES-23 into BALB/c mice bearing Meth-A fibrosarcoma and Colon 26 adenoca rcinoma, the tumor accumulation of TES-23 was greater than that of the cont rol IgG. In the present study, we report the anti-tumor effects of this mon oclonal antibody in mice bearing Meth-A fibrosarcoma. Mice treated with the immunoconjugate showed improved survival with no side effects. This result indicates that common antigens may be found in different kinds of tumor en dothelial cells, and that TES-23 might recognize these antigens.