Targeting immunotherapy for bladder cancer by using anti-CD3 × CD155 bispecific antibody

To investigate whether CD155 is an attractive target for T cell-mediated immunotherapy against human bladder cancer, we examined the novel bispecific antibody anti-CD3 x anti-CD155 (CD155Bi-Ab) for its ability to redirect activated T cells (ATCs) to target bladder cancer cells was examined. Expression of CD155 was detected by flow cytometry on the surface of bladder cancer cells, including T24 and Pumc-91 cells, and their chemotherapeutic drug-resistant counterparts. ATCs generated from healthy donors were stimulated with anti-CD3 monoclonal antibody, anti-CD28 monoclonal antibody and interleukin-2 (IL-2) for 14 days. The cytotoxic activity of ATCs armed with CD155Bi-Ab against bladder cancer cells was detected by LDH and luciferase quantitative assay. Furthermore, ATCs generated from bladder cancer patients were also armed with CD155Bi-Ab to verity the cell killing by the same methods. In contrast to unarmed ATCs, CD155Bi-armed ATCs against bladder cancer cells were increased cytotoxic activity at effector/target (E/T) ratios of 5:1, 10:1, and 20:1, with more IFN-γ, TNF-α secreting. It is worth noting that in spite of the presence of immunosuppression in bladder cancer patients and the drug resistance in chemotherapeutic drug-resistant cancer cell lines, not only the anti-tumor effect of CD155Bi-armed ATCs generated from bladder cancer patients still showed significantly but only higher level of activation marker CD69 was expressed. Taken together, our results suggest that CD155 is an effective target for the CD155-positive bladder cancer. And CD155Bi-Ab-armed ATCs are promisingly to provide a novel strategy for current CD155-positive bladder cancer therapy.