[Development of anti-tumor blood vessel antibodies by phage display method]

Tumor blood vessels are essential for tumor growth. Therefore, these blood vessels are potential targets for anti-cancer therapy. The purpose of this study is to develop anti-tumor endothelial cell (TEC) antibodies for delivering anti-cancer agents or drugs. To achieve this goal, we utilized the phage antibody display library method to create monoclonal antibodies in vitro. Accordingly, we developed anti-TEC antibodies from an single chain Fv fragment (scFv) phage display library prepared using the Fv genes amplified from the mRNAs isolated from the TEC-immunized mice. The size of the phage antibody library prepared from the mRNA of the TEC-immunized mice was approximately 1.3x10(7) CFU. To select and enrich for the phages displaying the anti-TEC antibodies, cell panning was performed first using the TEC followed by subtractive panning using the normal endothelial cell. After five cycles of panning, the affinity of bound phage clones increased approximately 10 000 folds. Subsequently, clones isolated from the post-panning output library were tested for their antigen-specificity by ELISA and western blotting. One of the scFv phage clones showing antigen-specificity recognized only TEC in vitro, and when injected into the Colon26 bearing mice, this clone accumulated more on the tumor tissue than the wild type phage. These results suggest that the isolated an antibody and this clone's target molecule could be potentially useful for novel anti-tumor therapies.