CD274 and neoplasm: The implantation of a hyaluronic acid hydrogel containing CAR-T cells targeting human chondroitin sulfate proteoglycan 4, along with polymer nanoparticles encapsulating the cytokine interleukin-15 and platelets conjugated with the checkpoint inhibitor programmed death-ligand 1 (PD-L1), into the tumor cavity of mice with resected subcutaneous melanoma inhibits local tumor recurrence and suppresses the growth of distant tumors through the abscopal effect.