Bi-specific Antibody Y111, Targeting PD-L1 and CD3 Considerably Enhances the Therapeutic Efficacy of Adoptive Transferred Vγ2Vδ2 T Cells

Abstract Background: Anti-cancer immunotherapy based on the adoptive transfer of Vγ2Vδ2 T cells has benefited to some patients in clinical trials, but the overall responses are inconsistent. Therefore, new strategies are urgently needed to improve the current therapy. Methods: In this study, a designed bispecific antibody Y111, which binds to both CD3 and PD-L1, is applied to optimally potentiate Vγ2Vδ2 T cell-based killing of cancer cells. The binding activities of Y111 was determined by Flow cytometry. CFSE/PI-based flow cytometry was applied to check the re-directed killing ability induced by Y111 in the condition of using T cell subsets, or expanded- and purified- Vγ2Vδ2 T cells as effector cells. Moreover, expanded- and purified- Vγ2Vδ2 T cells were co-cultured with tumor cells in the presence/absence of Y111 to assess the activation, degranulation, and cytokine production by intracellular cytokine staining, and CBA method. Finally, NPG-based subcutaneous tumor mouse models were used to check the in vivo therapeutic efficacy of the combination of transfused Vγ2Vδ2 T cells and Y111. Results: Due to its binding activities, Y111 apparently prompts fresh αβ-mediated lysis of tumor cell line H358 cells, but spare the effect on the fresh enriched Vγ2Vδ2 T cells from the same donors. However, Y111 increases cytotoxicity of expanded and purified Vγ2Vδ2 T cells against various NSCLC-derived tumor cell lines in a tumor cell dependent fashion. Y111 also prompted the releases of granzyme B, IFNγ and TNFα. Supporting to these observations in vitro , a combination of adoptive transferring Vγ2Vδ2 T cell and Y111 into the tumor-bearing NPG mice inhibited the growth of the established tumors in the mice. Conclusions: Taken together, our data suggest clinical potential for adoptive transferring the bispecific antibody-armored Vγ2Vδ2 T cells to treat solid tumors, such as NSCLC.