Chemical engineering of γδ T cells with cancer cell-targeting antibodies for enhanced tumor immunotherapy

Gamma delta (γδ) T cells hold great promise in adoptive cell therapy, but suffer from low tumor-targeting efficiency. Herein, we report the development of antibody-γδ T cell conjugates for enhanced tumor therapy. By evaluating different biomolecules residing on the cell surface, sialic acids-the terminal sugars of various cell-surface glycans-are identified as the optimum site for anchoring antibodies onto γδ T cells via metabolic glycan labeling with unnatural sugars containing a bioorthogonal functional group. A programmed death-ligand 1 (PD-L1)-specific nanobody (αPD-L1) is conjugated onto γδ T cells via click chemistry and the resulting αPD-L1-γδ T cells exhibit enhanced cytotoxicity towards PD-L1-positive cancer cell lines, patient-derived primary cancer cells, and xenografted tumors in living mice. Mechanistically, αPD-L1-γδ T cells target cancer cells and tumors via binding to PD-L1 and induce cancer cell pyroptosis. Furthermore, αPD-L1-γδ T cells remodel the tumor microenvironment to be immune-active, at least partially through the recruitment and activation of CD8(+) T cells via the CCR5/CCL5 axis. This work provides a versatile strategy for chemical engineering of γδ T cells for improved therapeutic applications.