Heterogeneity of tumor cells and their microenvironment can affect outcome in cancer. Blockade of immune checkpoints (ICPs) expressed only on a subset of immune cells leads to durable responses in advanced melanoma. Tissue-resident memory T (TRM) cells have recently emerged as a distinct subset of memory T cells in nonlymphoid tissues. Here, we show that functional properties and expression of ICPs within tumor-infiltrating lymphocytes (TILs) differ from those of blood T cells. TILs secrete less IL-2, IFN-γ, and TNF-α compared with circulating counterparts, and expression of VEGF correlated with reduced TIL infiltration. Within tumors, ICPs are particularly enriched within T cells with phenotype and genomic features of TRM cells and the CD16+ subset of myeloid cells. Concurrent T cell receptor (TCR) and tumor exome sequencing of individual metastases in the same patient revealed that interlesional diversity of TCRs exceeded differences in mutation/neoantigen load in tumor cells. These findings suggest that the TRM subset of TILs may be the major target of ICP blockade and illustrate interlesional diversity of tissue-resident TCRs within individual metastases, which did not equilibrate between metastases and may differentially affect the outcome of immune therapy at each site.
Chandra Sekhar Boddupalli, Noffar Bar, Krishna Kadaveru, Michael Krauthammer, Natopol Pornputtapong, Zifeng Mai, Stephan Ariyan, Deepak Narayan, Harriet Kluger, Yanhong Deng, Rakesh Verma, Rituparna Das, Antonella Bacchiocchi, Ruth Halaban, Mario Sznol, Madhav V. Dhodapkar, Kavita M. Dhodapkar
Melanoma tissue is enriched for memory T cells expressing higher levels of inhibitory checkpoints compared with T cells in peripheral blood.