Identifying tumor antigen-specific T cells from cancer patients has important implications for immunotherapy diagnostics and therapeutics. Here, we show that CD103+CD39+ tumor-infiltrating CD8 T cells (CD8 TIL) are enriched for tumor-reactive cells both in primary and metastatic tumors. This CD8 TIL subset is found across six different malignancies and displays an exhausted tissue-resident memory phenotype. CD103+CD39+ CD8 TILs have a distinct T-cell receptor (TCR) repertoire, with T-cell clones expanded in the tumor but present at low frequencies in the periphery. CD103+CD39+ CD8 TILs also efficiently kill autologous tumor cells in a MHC-class I-dependent manner. Finally, higher frequencies of CD103+CD39+ CD8 TILs in patients with head and neck cancer are associated with better overall survival. Our data thus describe an approach for detecting tumor-reactive CD8 TILs that will help define mechanisms of existing immunotherapy treatments, and may lead to future adoptive T-cell cancer therapies.

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During the development of experimental autoimmune encephalomyelitis (EAE), the proportion of pathogenic and myelin-specific cells within CNS-infiltrating cytokine producing T helper (Th) cells is unknown. Using an IL-17A-IFN-γ double reporter mouse and I-Ab/MOG38–49 tetramer, we show here that IL-17+ IFN-γ+ Th cells, which are expanded in the CNS during EAE, are highly enriched in MOG-specific T cells. We further demonstrate that IL-23 is essential for the generation and expansion of IFN-γ producing Th17 cells independently of the Th1-associated transcription factors T-bet, STAT1 and STAT4. Furthermore, Th17 and IL-17+ IFN-γ+ Th cells can induce CNS autoimmunity independently of T-bet. While T-bet is crucial for Th1 mediated EAE T-bet is dispensable for Th17 cell-mediated autoimmunity. Our results suggest the existence of different epigenetic programs that regulate IFN-γ expression in Th1 and Th17 cells.

The neutralization of alpha 4 integrin is currently used as treatment in several autoimmune diseases and is thought to prevent the entry of most immune cells in target tissues. Here, we showed that selective deletion of alpha4 integrin in T cells did not prevent but delayed the development of experimental autoimmune encephalomyelitis (EAE). Whereas both Th1 and Th17 cells infiltrate the central nervous system (CNS) of wild type mice, T cells present in the CNS of mice lacking alpha4 integrin were mainly enriched in Th17 cells suggesting that this T cell subset uses other integrins to access the CNS. In contrary, alpha4 integrin expression is important for Th1 cells to enter the CNS and for the stability of their Th1 associated genetic program. Therefore, our data suggest that anti-alpha4 integrin antibody treatment may be more efficient in the treatment of Th1 rather than Th17 mediated disease.

Despite the success of checkpoint blockade in some cancer patients, there is an unmet need to improve outcomes. Targeting alternative pathways, such as costimulatory molecules (e.g. OX40, GITR, and 4-1BB), can enhance T cell immunity in tumor-bearing hosts. Here we describe the results from a phase Ib clinical trial (NCT02274155) in which 17 patients with locally advanced head and neck squamous cell carcinoma (HNSCC) received a murine anti-human OX40 agonist antibody (MEDI6469) prior to definitive surgical resection. The primary endpoint was to determine safety and feasibility of the anti-OX40 neoadjuvant treatment. The secondary objective was to assess the effect of anti-OX40 on lymphocyte subsets in the tumor and blood. Neoadjuvant anti-OX40 was well tolerated and did not delay surgery, thus meeting the primary endpoint. Peripheral blood phenotyping data show increases in CD4+ and CD8+ T cell proliferation two weeks after anti-OX40 administration. Comparison of tumor biopsies before and after treatment reveals an increase of activated, conventional CD4+ tumor-infiltrating lymphocytes (TIL) in most patients and higher clonality by TCRβ sequencing. Analyses of CD8+ TIL show increases in tumor-antigen reactive, proliferating CD103+ CD39+ cells in 25% of patients with evaluable tumor tissue (N = 4/16), all of whom remain disease-free. These data provide evidence that anti-OX40 prior to surgery is safe and can increase activation and proliferation of CD4+ and CD8+ T cells in blood and tumor. Our work suggests that increases in the tumor-reactive CD103+ CD39+ CD8+ TIL could serve as a potential biomarker of anti-OX40 clinical activity.