Immune checkpoint inhibition using monoclonal antibodies targeting cytotoxic T-lymphocyte antigen-4 (CTLA-4) and programmed cell death receptor-1 (PD-1) to enhance cytotoxic T-lymphocyte response against tumours has been used in the management of several malignancies including metastatic melanoma. Although preliminary studies in patients with untreated metastatic melanoma demonstrated significantly increased progression-free survival, there is an unmet need for clinical decision-making tools that can be used for monitoring the efficacy of these costly agents, their potential side effects and the identification of patients with the most suitable immunological profile for this treatment approach. The development of non-invasive imaging methods and imaging biomarkers of response to immune checkpoint inhibitors could therefore provide important diagnostic and prognostic information. This project builds on existing technologies in Cambridge to develop structural and functional imaging approaches for monitoring tumour response to immune checkpoint inhibitors. Magnetic resonance imaging (MRI), radiolabelling of neutrophils for single-photon emission computed tomography (SPECT) imaging and intravital imaging are explored as part of a co-clinical study on metastatic melanoma patients and syngeneic mouse models of cancer immunotherapy.