TNF and neoplasm: In NSG mouse‐models, hYP218 CAR T cells demonstrated anti‐tumour efficacy and persisted in the tumour microenvironment in a functional state at day 40 posttreatment with expression of activation markers CD39 and CD69, increased production of IFN‐γ and TNF‐α and ability to kill tumour cells in vitro when isolated from tumours.