CD274 and neoplasm: Tumours with high PD-L1 expression, high mutational burden and increased lymphocytic infiltration are more likely to respond to ICT.3–5 However, there is no single accurate biomarker of ICT response that can be applied across cancers.6 As ICT primarily acts upon adaptive immunity, in-depth profiling of T cell phenotype and specificity in responders and non-responders to therapy improves development of predictive biomarkers for response.7–9