Intratumoral immune triads are required for immunotherapy-mediated elimination of solid tumors.

Tumor-specific CD8+ T cells are frequently dysfunctional and unable to halt tumor growth. We investigated whether tumor-specific CD4+ T cells can be enlisted to overcome CD8+ T cell dysfunction within tumors. We find that the spatial positioning and interactions of CD8+ and CD4+ T cells, but not their numbers, dictate anti-tumor responses in the context of adoptive T cell therapy as well as immune checkpoint blockade (ICB): CD4+ T cells must engage with CD8+ T cells on the same dendritic cell during the effector phase, forming a three-cell-type cluster (triad) to license CD8+ T cell cytotoxicity and cancer cell elimination. When intratumoral triad formation is disrupted, tumors progress despite equal numbers of tumor-specific CD8+ and CD4+ T cells. In patients with pleural mesothelioma treated with ICB, triads are associated with clinical responses. Thus, CD4+ T cells and triads are required for CD8+ T cell cytotoxicity during the effector phase and tumor elimination.

Multiplexed spatial profiling of Hodgkin Reed-Sternberg cell neighborhoods in classic Hodgkin lymphoma.

PURPOSE: Classic Hodgkin lymphoma (cHL) is a B cell lymphoma that occurs primarily in young adults and, less frequently, in elderly individuals. A hallmark of cHL is the exceptional scarcity (1-5%) of the malignant Hodgkin Reed-Sternberg (HRS) cells within a network of non-malignant immune cells. Molecular determinants governing the relationship between HRS cells and their proximal microenvironment remain largely unknown. EXPERIMENTAL DESIGN: We performed spatially resolved multiplexed protein imaging and transcriptomic sequencing to characterize HRS cell states, cellular neighborhoods, and gene expression signatures of 23.6 million cells from 36 newly diagnosed Epstein-Barr virus (EBV) positive and EBV-negative cHL tumors. RESULTS: We show that MHC-I expression on HRS cells is associated with immune inflamed neighborhoods containing CD8+ T cells, MHC-II+ macrophages, and immune checkpoint expression (i.e., PD-1 and VISTA). We identified spatial clustering of HRS cells, consistent with the syncytial variant of cHL, and its association with T cell excluded neighborhoods in a subset of EBV-negative tumors. Finally, a subset of both EBV-positive and EBV-negative tumors contained regulatory T cells high neighborhoods harboring HRS cells with augmented proliferative capacity. CONCLUSIONS: Our study links HRS cell properties with distinct immunophenotypes and potential immune escape mechanisms in cHL.