The use of light in cancer immunotherapy

The breakthrough of immunotherapy for cancer has introduced promising new options, but nonetheless only a minority of cancer patients show significant clinical benefit. This situation has inspired two avenues of research to find solutions to this problem: mechanistic studies to decipher the working mechanisms of immunotherapies and to investigate why many patients do not respond, and studies developing combination treatments to achieve clinical benefit in situations where immunotherapy alone is not sufficient. This thesis explores both these avenues by investigating applications of visible light in immunotherapy of cancer in pre-clinical models. We developed optical imaging platforms for visualization of immune cells and immunotherapies, which can shed light on the immunological events after administration of immunotherapy. In addition, we investigated novel therapies based on the combination of tumor ablation by Photodynamic Therapy and different types of immunotherapy. Our findings may prove useful in understanding success and failure of immunotherapy, and provide new combination treatment options when the efficacy of monotherapy is insufficient.