Conventional memory T cells classically include central memory T (TCM) cells, residing in lymphoid organs, and effector memory T (TEM) cells, circulating through various tissues. Recently, a novel population of memory T cells has gained interest, namely tissue resident memory T (TRM) cells, which persist in tissues and do not recirculate. It is described that these cells reside in human tumors playing a role in tumor-specific T-cell responses. We found by flow cytometry that between 50%–80% of the CD8+ T cells in human ovarian carcinomas are CD103+CD69+TRM cells. RNA-seq of TRM and their re-circulating counterparts from 7 different human carcinomas showed a very distinctive phenotype, characterized by co-upregulation of effector (GZMB, IFNG) and exhaustion (PD-1, TIM3) markers, along with transcription factors and signaling molecules likely involved in the acquisition of the TRM phenotype. Unexpectedly, we found very little overlap between the TCR repertoire of both populations in multiple tumors, and TRM T cells consistently showed significantly higher clonality. Tumor antigen-specific TRM T cells intratumorally transferred into syngeneic mice were more effective at delaying tumor growth compared with their tumor antigen-specific recirculating counterparts. Finally, both the acquisition and the maintenance of a TRM phenotype within the CD8 T cell compartment at tumor beds are dependent on exposure to tumor cognate antigen. Together, our data indicate that TRM CD8+ T cells, but not their CD103− counterparts, represent tumor antigen-specific effector lymphocytes actively exerting anti-tumor immune pressure in the ovarian cancer microenvironment.

Despite the emergence of immunotherapy for the treatment of cancer, many of the fundamental mechanisms which characterize tumors that are amenable to immunotherapy and/or drive superior endogenous anti-tumor immune responses likely remain uncharacterized. We have identified a single-nucleotide polymorphism, rs13205210, in the gene encoding UHRF1BP1 (UBP). This polymorphism is associated with a dramatic survival benefit in ovarian cancer patients. The function of the protein encoded by this gene remains elusive, however we demonstrate UBP-ablated ovarian tumor cells display global modulation of methylated cytosine, suggesting it has a role as an epigenetic integrator. Interestingly, this polymorphism is also associated with systemic lupus erythematosus, an immune-driven pathology. Accordingly, we demonstrate that human ovarian tumors with polymorphic UBP display increased frequency of activated CD8+ T cells, as well as a type I IFN signature. In vivo, inducible autochthonous murine ovarian tumors driven by oncogenic Kras and ablation of p53, in which UBP was conditionally deleted, demonstrated a significantly enhanced overall survival with a concomitant type I IFN and CXCR3-chemokine signature, as well as an enhanced T cell infiltrate compared to controls. RNA-seq analyses of UBP-deficient ovarian tumors revealed an elevation of inflammatory cytokines and the activation of canonical inflammatory pathways. Furthermore, ectopic expression of polymorphic human UBP in ovarian tumor cells drove elevated NF-kB signaling under inflammatory conditions. Overall our work suggests that UBP functions as a regulator of inflammation, which is unleashed in the polymorphic variant leading to enhanced anti-tumor immunity.

Ovarian carcinoma microenvironmental T cells exert clinically relevant pressure against malignant progression; however current immunotherapies rarely induce ovarian cancer regression. Here we investigate CD277-containing butyrophilin 3A1 (BTN3A1), a poorly investigated immunoregulatory pathway driven by myeloid and tumor cells in ovarian tumor beds. We show that BTN3A1 is overexpressed in ovarian cancer and is associated with a significant survival disadvantage in these patients (n=200). Concomitantly, ectopic expression of BTN3A1 on APCs inhibits αβ T cell proliferation and Th1 cytokine production. Proteomic analyses and binding assays demonstrate that BTN3A1 interacts with the CD45 phosphatase and elements of the TCR. Consequently, TCR ligation in the presence of BTN3A1 inhibits the segregation of CD45 from the immune synapse and blunts downstream signaling by antagonizing the phosphorylation of CD3Zeta, Lck, and Zap70. We developed fully human αCD277 antibodies which rescue αβ T cell proliferation and Th1 cytokine responses, while driving the infiltration of T cells into tumor beds, delaying ovarian tumor progression in novel BTN3A1+ humanized mice and xenograft studies. Paradoxically, αCD277 antibodies promote the activation of γδ T cells by driving a conformational transformation of BTN3A1. Thus, co-transfer of γδ and Ag-specific αβ T cells in the presence of αCD277 antibodies synergize to further impair malignant progression in vivo. Overall, we show that BTN3A1 drives αβ T cell dysfunction in ovarian cancer, while αCD277 antibodies transform this molecule from immunosuppressive to immunostimulatory by rescuing αβ T cells and activating γδ T cells, thus dynamically unleashing T cell-driven antitumor immunity.