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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. Identifying and enumerating tumor-specific CD8 T cells are important for assessing cancer prognosis and therapy efficacy. Here the authors show that CD39 and CD103 mark a subset of tumor-infiltrating CD8 T cells that are tumor-reactive and exhibit characteristics of exhausted or tissue-resident memory T cells.

CD4+ Th cells play a key role in orchestrating immune responses, but the identity of the CD4+ Th cells involved in the antitumor immune response remains to be defined. We analyzed the immune cell infiltrates of head and neck squamous cell carcinoma and colorectal cancers and identified a subset of CD4+ Th cells distinct from FOXP3+ Tregs that coexpressed programmed cell death 1 (PD-1) and ICOS. These tumor-infiltrating lymphocyte CD4+ Th cells (CD4+ Th TILs) had a tissue-resident memory phenotype, were present in MHC class II-rich areas, and proliferated in the tumor, suggesting local antigen recognition. The T cell receptor repertoire of the PD-1+ICOS+ CD4+ Th TILs was oligoclonal, with T cell clones expanded in the tumor, but present at low frequencies in the periphery. Finally, these PD-1+ICOS+ CD4+ Th TILs were shown to recognize both tumor-associated antigens and tumor-specific neoantigens. Our findings provide an approach for isolating tumor-reactive CD4+ Th TILs directly ex vivo that will help define their role in the antitumor immune response and potentially improve future adoptive T cell therapy approaches.

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. Different neoadjuvant therapies have been proposed to improve immunotherapy for cancer treatment. Here, the authors perform a phase Ib clinical trial where an agonist OX40 antibody provided prior to surgery is well tolerated and increases proliferation and activation of tumor antigen-specific T cells in head and neck cancer patients.

The provision of T cell co-stimulation via members of the TNFR super-family, including OX40 (CD134) and 4-1BB (CD137), provides critical signals that promote T cell survival and differentiation. Recent studies have demonstrated that ligation of OX40 can augment T cell-mediated anti-tumor immunity in pre-clinical models and more importantly, OX40 agonists are under clinical development for cancer immunotherapy. OX40 is of particular interest as a therapeutic target as it is not expressed on naïve T cells but rather, is transiently up-regulated following TCR stimulation. Although TCR engagement is necessary for inducing OX40 expression, the downstream signals that regulate OX40 itself remain unclear. In this study, we demonstrate that OX40 expression is regulated through a TCR and common gamma chain cytokine-dependent signaling cascade that requires JAK3-mediated activation of the downstream transcription factors STAT3 and STAT5. Furthermore, combined treatment with an agonist anti-OX40 mAb and IL-2 augmented tumor immunotherapy against multiple tumor types. Dual therapy was also able to restore the function of anergic tumor-reactive CD8 T cells in mice with long-term well-established (>5 wks) tumors, leading to increased survival of the tumor-bearing hosts. Together, these data reveal the ability of TCR/common gamma chain cytokine signaling to regulate OX40 expression and demonstrate a novel means of augmenting cancer immunotherapy by providing dual anti-OX40/common gamma chain cytokine-directed therapy.

Background The efficacy of checkpoint blockade immunotherapies in colorectal cancer is currently restricted to a minority of patients diagnosed with mismatch repair-deficient tumors having high mutation burden. However, this observation does not exclude the existence of neoantigen-specific T cells in colorectal cancers with low mutation burden and the exploitation of their anti-cancer potential for immunotherapy. Therefore, we investigated whether autologous neoantigen-specific T cell responses could also be observed in patients diagnosed with mismatch repair-proficient colorectal cancers. Methods Whole-exome and transcriptome sequencing were performed on cancer and normal tissues from seven colorectal cancer patients diagnosed with mismatch repair-proficient tumors to detect putative neoantigens. Corresponding neo-epitopes were synthesized and tested for recognition by in vitro expanded T cells that were isolated from tumor tissues (tumor-infiltrating lymphocytes) and from peripheral mononuclear blood cells stimulated with tumor material. Results Neoantigen-specific T cell reactivity was detected to several neo-epitopes in the tumor-infiltrating lymphocytes of three patients while their respective cancers expressed 15, 21, and 30 non-synonymous variants. Cell sorting of tumor-infiltrating lymphocytes based on the co-expression of CD39 and CD103 pinpointed the presence of neoantigen-specific T cells in the CD39 + CD103 + T cell subset. Strikingly, the tumors containing neoantigen-reactive TIL were classified as consensus molecular subtype 4 (CMS4), which is associated with TGF-β pathway activation and worse clinical outcome. Conclusions We have detected neoantigen-targeted reactivity by autologous T cells in mismatch repair-proficient colorectal cancers of the CMS4 subtype. These findings warrant the development of specific immunotherapeutic strategies that selectively boost the activity of neoantigen-specific T cells and target the TGF-β pathway to reinforce T cell reactivity in this patient group.

Key Points Conventional immunotherapies for autoimmune, allergic and inflammatory diseases prevent disease symptoms by inducing immunosuppression, but at the same time, cause opportunistic infections and cancer. Therefore, an ideal immunotherapeutic strategy for a T-cell-mediated disease would directly target the antigen-specific T cells that are responsible for the disease pathogenesis. Optimal activation of naive T cells requires not only interaction between the T-cell receptor and antigen–MHC complexes, but also co-stimulation provided by co-stimulatory ligands expressed by antigen-presenting cells. Among several co-stimulatory receptors, signals through CD28 and OX40 are indispensable for T cells to respond to antigen and for the generation of antigen-specific memory T cells. Targeting the T-cell co-stimulatory molecules CD28 and OX40 is a promising strategy to control T-cell-mediated immune disorders, by regulating the T cells that cause disease. Whereas CD28 blockade mainly suppresses the generation of effector T cells from naive T cells, OX40 blockade inhibits the survival and activation of effector T cells generated from either naive or memory T cells in many models. As CD28 blockade is unable to effectively suppress effector T-cell function or reactivation of memory T cells, this blockade might be insufficient to prevent ongoing symptoms in certain T-cell-mediated diseases. By contrast, blockade of OX40–OX40 ligand (OX40L) interactions alone inhibits ongoing effector T-cell responses, and therefore might be a favourable strategy in certain clinical settings for T-cell-mediated diseases. The presence of OX40 + lymphocytes and OX40L + cells at the sites of inflammation in T-cell-mediated disorders, such as autoimmunity, allergic and inflammatory diseases, and graft-versus-host disease, indicates the possible involvement of OX40–OX40L interactions in the pathogenesis of these diseases. In fact, targeting OX40 using OX40-specific monoclonal antibodies, OX40–immunoglobulin fusion proteins or OX40-specific immunotoxin is therapeutic in terms of reducing even ongoing disease symptoms in several animal models of these diseases. Targeting OX40 in mouse models of disease is effective not only for autoimmune and allergic diseases, but also for tissue inflammation during viral infection without delaying viral clearance, indicating additional benefits of targeting OX40 as an anti-inflammatory therapy, as well as an immunosuppressive regimen. Deliberate ligation of OX40 induces favourable antitumour effects in cancer-bearing hosts by enhancing effector T-cell functions, and can be augmented with protocols that involve other stimulatory molecules, such as granulocyte–macrophage colony-stimulating factor, 4-1BB-specific antibody and IL-12. Therapeutic reagents that target OX40 and OX40L will soon be tested in phase I clinical trials for T-cell-mediated diseases and patients with certain types of cancer. An emerging immunotherapeutic strategy for T-cell-mediated diseases is to directly target antigen-specific T cells that are responsible for the clinical effects, without causing general widespread immunosuppression. A T-cell co-stimulatory molecule, OX40, which is transiently expressed after antigen recognition, fits these criteria in several immune-mediated diseases. In vivo blockade of OX40 signalling specifically suppresses the function of recently activated autoantigen-specific T cells, leading to inhibition of autoimmune disease without severe immunosuppression. In addition, deliberate ligation of OX40 in tumour-bearing hosts enhances anticancer immunity. We discuss how targeting OX40 is potentially an ideal strategy for immune-based therapies in several human diseases.

It is well-known that vaccines comprising of irradiated whole tumor cells or tumor-derived heat shock proteins can generate tumor-specific immune responses. In contrast, we showed recently that vaccines composed of autophagosomes (DRibbles) derived from syngeneic sarcomas could induce cross-reactive T-cell responses and cross-protection against the tumor. This unusual property of DRibbles was related to the selective recruitment of defective ribosomal products (DRiPs) and other short-lived proteins (SLiPs) into autophagosomes via sequestosome (SQSTM1, p62) mediated association of ubiquitinated SLiPs to the autophagy gene product LC3. Here, we extend our observations to mammary carcinomas from mice of different genetic background. We demonstrated that combined of intranodal administration of autologous or allogeneic DRibbles together with anti-OX40 antibody led to robust proliferation, expansion, and differentiation of memory and effector T cells. We also showed that SLiPs is an excellent source of antigen for cross-priming of CD8 + T-cells that recognize shared tumor antigens in the context of host MHC class I molecules. Thus, our results provide a strong basis for novel clinical trials that combine allogeneic “off-the-shelf” DRibble vaccines together with antibodies against co-stimulatory molecules.

Effective tumor immunotherapy may require not only activation of anti-tumor effector cells, but also abrogation of tumor-mediated immunosuppression. The cytokine TGF-β, is frequently elevated in the tumor microenvironment and is a potent immunosuppressive agent and promoter of tumor metastasis. OX40 (CD134) is a member of the TNF-α receptor superfamily and ligation by agonistic antibody (anti-OX40) enhances effector function, expansion, and survival of activated T cells. In this study, we examined the therapeutic efficacy and anti-tumor immune response induced by the combination of a small molecule TGF-β signaling inhibitor, SM16, plus anti-OX40 in the poorly immunogenic, highly metastatic, TGF-β-secreting 4T1 mammary tumor model. Our data show that SM16 and anti-OX40 mutually enhanced each other to elicit a potent anti-tumor effect against established primary tumors, with a 79% reduction in tumor size, a 95% reduction in the number of metastatic lung nodules, and a cure rate of 38%. This positive treatment outcome was associated with a 3.2-fold increase of tumor-infiltrating, activated CD8 + T cells, an overall accumulation of CD4 + and CD8 + T cells, and an increased tumor-specific effector T cell response. Complete abrogation of the therapeutic effect in vivo following depletion of CD4 + and CD8 + T cells suggests that the anti-tumor efficacy of SM16+ anti-OX40 therapy is T cell dependent. Mice that were cured of their tumors were able to reject tumor re-challenge and manifested a significant tumor-specific peripheral memory IFN-γ response. Taken together, these data suggest that combining a TGF-β signaling inhibitor with anti-OX40 is a viable approach for treating metastatic breast cancer.

Immune responses wane during aging, posing challenges to the potential effectiveness of cancer immunotherapies. We previously demonstrated that in the context of a promising immunotherapeutic, OX40 agonist (αOX40), older animals exhibited impaired anti-tumor immune responses and diminished CD4 T cell effector differentiation. In this study, we hypothesized that tumor immune responses could be maintained during aging through caloric restriction (CR) or dietary supplementation with resveratrol (RES), a CR mimetic. Mice were placed on either a calorically restricted diet or a RES-formulated diet starting between 4 and 6 months of age and continued until mice reached 12 months of age. Tumor immune responses were assessed after challenging with either sarcoma or breast tumor cells followed by αOX40 treatment. Our results show that CR, but not RES, maintained OX40-mediated anti-tumor immunity. In addition, CR fully sustained antigen-specific CD4 T cell priming in aged hosts (12 months old), whereas tumor-specific CD8 T cell priming was not fully maintained compared to young reference animals (2 months old). Thus, CR appears to maintain immunological fitness of the CD4 T cell priming environment during aging, which is critical for optimal OX40-mediated responses.

The expression of OX40 (CD134) on activated CD4+ T cells has been associated with favorable cancer patient outcomes. Because of recent reports that sentinel lymph nodes (SLNs) may represent an immunosuppressive environment, we investigated the expression of OX40 in SLNs from patients with primary cutaneous melanoma. Samples of peripheral blood lymphocytes and a section of 71 SLNs from 53 patients with clinically node negative melanoma were purified for CD4+ T cells, stained for OX40, and analyzed by flow cytometry. The mean percentage of OX40 on CD4 T cells in the SLNs versus peripheral blood lymphocytes was related indirectly to the T stage of the primary tumor and was decreased in ulcerated primary tumors and positive sentinel nodes. The expression of OX40 on CD4+ T cells in SLNs draining primary melanomas decreased with more advanced tumor features (higher T stage, ulceration) and nodal involvement, suggesting that such tumors may have an immunosuppressive effect on the SLN microenvironment.