V gamma 2 x PD-L1, a Bispecific Antibody Targeting Both the V gamma 2 TCR and PD-L1, Improves the Anti-Tumor Response of V gamma 2V delta 2 T Cell

The potent cytotoxic property of V gamma 2V delta 2 T cells makes them attractive for adoptive T cell transfer therapy. The transfusing of the expanded V gamma 2V delta 2 T cells into cancer patients shows well-tolerated, but the clinical response rates are required to be improved, implying that there is still an unmet efficacy with low toxicity for this novel anti-tumor therapy. In this study, we test the anti-tumor efficacy of a Y-body-based bispecific antibody (bsAb) V gamma 2 x PD-L1 that preferentially redirects V gamma 2V delta 2 T cells to combat PD-L1 positive tumor cells. With nanomolar affinity levels to V gamma 2V delta 2 T cells and PD-L1+ tumor cells, V gamma 2 x PD-L1 bridges a V gamma 2V delta 2 T cell with a SKOV3 tumor cell to form a cell-to-cell conjugation. In a PD-L1-dependent manner, the bsAb elicits effective activation (CD25+CD69+), IFN gamma releasing, degranulation (CD107a+), and cytokine production (IFN gamma+ and TNF alpha+) of expanded V gamma 2V delta 2 T cells. The activations of the V gamma 2V delta 2 T cells eliminate PD-L1-expressing human cancer cell lines, including H1975, SKOV3, A375, H1299, and H2228 cells, but not PD-L1 negative cells including HEK-293 (293) cells and healthy PBMCs. Finally, we show that combining V gamma 2 x PD-L1 with adoptively transferring V gamma 2V delta 2 T cells inhibits the growth of existing tumor xenografts and increases the number of V gamma 2V delta 2 T cells into the tumor bed. V gamma 2 x PD-L1 represents a promising reagent for increasing the efficacy of adoptively transferred V gamma 2V delta 2 T cells in the treatment of PD-L1 positive malignant tumors.