Immunotherapy holds the potential to dramatically improve the curative prognosis of cancer patients. However, despite significant progress, a huge gap remains to be bridged to gain board success in the clinic. A first limiting factor in cancer immunotherapy is the low response rate in large fraction of the patients and an unmet need exists for more efficient - potentially synergistic - immunotherapies that improve upon or complement existing strategies. The second limiting factor is immune-related toxicity that can cause live-threatening situations as well as seriously impair the quality of life of patients. Therefore, there is an urgent need for safer immunotherapies that allow for a more target-specific engineering of the immune system. Strategies to engineer the immune system via a materials chemistry approach, i.e. immuno-engineering, have gathered major attention over the past decade and could complement or replace biologicals, and holds promise to contribute to resolving the current issues faced by the immunotherapy field. The overarching aim of this ERC project is to develop synergistic biomaterials strategies to engineer the immune system to fight cancer. We will address a number of fundamental questions with regard to optimal biomaterial design for immuno-engineering. Based on these findings, we will elucidate those therapeutic strategies that lead to synergistic engineering of innate and adaptive immunity in combination with remodeling the tumor microenvironment to become more responsive to therapeutic interventions.