Responsive biomaterials: optimizing control of cancer immunotherapy

Immunotherapy has emerged as an eminent and effective modality in the treatment of cancer. However, current cancer immunotherapies lack spatial and temporal control, resulting in systemic side effects and suboptimal patient outcomes. Responsive biomaterials have proven to be powerful tools for controlling cancer immunotherapies by providing precise control over the delivery and kinetics of immunotherapeutic cargoes. Here, we discuss biological barriers to cancer immunotherapy and how biomaterial-based strategies that respond to different stimuli — both internal and external — can be used to increase the therapeutic efficacy while reducing the toxicity of cancer immunotherapies. We examine the use of biomaterials that respond to physiological stimuli (pH, enzymes and redox potential) and exogenous energetic stimuli (light, magnetism and ultrasound) and expand upon the use of these strategies in propagating three key approaches in cancer immunotherapy: cancer vaccines, T cell-based therapy and therapies involving sustained delivery. Immunotherapy represents an important advance in cancer treatment, yet faces challenges owing to lack of precise control, leading to systemic effects and suboptimal results for patients. This Review explores how responsive biomaterials can enhance cancer immunotherapies by responding to various internal and external stimuli to regulate the delivery and behaviour of therapeutic agents, thereby improving efficacy and reducing toxicity in treatment methods such as cancer vaccines, T cell-based therapies and sustained delivery systems.