“…Through this highly modular platform, biocompatible materials can be employed as substrates for a wide spectrum of modulatory biomolecules, including cytokines 5 , antigens 10 , checkpoint inhibitors 43 , agonistic or antagonistic antibodies 44 , adjuvants 9, 11 , etc., to regulate the local environment and enhance the efficacy of immune cells in cancer immunotherapy 8 . Synthetic materials with tunable properties can enhance the pharmacokinetics of regulatory biomolecules in vivo 1,6,8 , and sometimes provide a necessary surface substrate for biomolecules to activate the cognate cell signaling 10,25,28 . Biomaterials fabricated with controlled size, shape, and composition -for example, microspheres, nanowires, and porous scaffolds -can also serve as a local adjuvant 2, 3, 7, 13 for biomolecules or engineered immune cells to exert tumor targeted toxicity without systemic diffusion, thus minimizing the off-target side effects.…”