During tumorigenesis, the hypoxic tumour environment promotes the formation of new blood vessels that show many abnormalities compared with healthy vasculature. Leukocyte adhesion to endothelial cells lining the tumour-associated vasculature is impaired and, consequently, effector immune cells cannot gain access to the tumour. In this study, the authors treated tumour-bearing mice with a tumour necrosis factor (TNF)–peptide fusion protein that targets TNF to the tumour-associated vasculature. They found that this therapy promoted the upregulation of adhesion molecules on endothelial cells and increased the infiltration of CD8+ T cells into tumours. In mice with ovalbumin-expressing tumours, delivery of the fusion protein markedly increased the antitumour responses of adoptively transferred ovalbumin-specific CD8+ T cells. The authors suggest that a similar approach could be used to improve the efficacy of adoptive T cell transfer-based therapies for cancer.