Autologous T cells are engineered via non-viral electroporation to express a mesothelin-targeted CAR (alpaca VHH binder with CD28 costimulation and CD3ζ signaling) that mediates antigen-specific cytotoxicity against MSLN+ tumor cells. The cells also secrete an anti-PD-1 nanobody and an anti-CTLA-4 antibody to provide local checkpoint blockade within the tumor microenvironment, enhancing T-cell activation, proliferation, and persistence while reducing exhaustion and Treg-mediated suppression.