Resident Memory T Cells in Regional Lymph Nodes Sustain Immunity to Cancer

While immune responses against primary tumors are critically important, T cells must also be capable of functioning at sites where cancers metastasize. Here we investigated how resident memory (TRM) and circulating memory (TCIRCM) CD8 T cells potentiate immunity to cancer in diverse tissue microenvironments. Based on a mouse model of immunity to melanoma with associated autoimmune vitiligo, we show that tumor-specific memory T cells are capable of forming a widespread network of transcriptionally distinct subsets, throughout lymphoid tissues and visceral organs. Among these, we discovered a population of TRM cells that reside durably within LNs, where they protect against invading melanoma cells. These LN-resident memory (LN TRM) cells adopt a transcriptional program that is distinct from TRM cells in other tissues, and which uniquely predicts survival in melanoma patients with regional LN metastases. This work reveals a novel role for TRM cells in durable immunity to cancer at crucial sites of metastasis.