Enhanced anti-tumour immunity requires the interplay between resident and circulating memory CD8+ T cells

The goal of successful anti-tumoural immunity is the development of long-term protective immunity to prevent relapse. Infiltration of tumours with CD8 + T cells with a resident memory (Trm) phenotype correlates with improved survival. However, the interplay of circulating CD8 + T cells and Trm cells remains poorly explored in tumour immunity. Using different vaccination strategies that fine-tune the generation of Trm cells or circulating memory T cells, here we show that, while both subsets are sufficient for anti-tumour immunity, the presence of Trm cells improves anti-tumour efficacy. Transferred central memory T cells (Tcm) generate Trm cells following viral infection or tumour challenge. Anti-PD-1 treatment promotes infiltration of transferred Tcm cells within tumours, improving anti-tumour immunity. Moreover, Batf3-dependent dendritic cells are essential for reactivation of circulating memory anti-tumour response. Our findings show the plasticity, collaboration and requirements for reactivation of memory CD8 + T cells subsets needed for optimal tumour vaccination and immunotherapy. Circulating memory cells include central memory T cells retaining the ability to enter the lymph nodes whereas tissue resident memory cells are confined to the parenchymal tissues. Here the authors explore the interplay between the two T-cell types and show that both cooperate in anti-tumour immunity.