Tumor Immune Escape Mechanisms Research Articles

Molecular and Genetic Characterization of MHC Deficiency Identifies EZH2 As a Therapeutic Target for Restoring MHC Expression in Diffuse Large B-Cell Lymphoma

Introduction: Among the tumor immune escape mechanisms described to date, alterations in the expression of major histocompatibility complex (MHC) molecules play a crucial role in the development of diffuse large B-cell lymphoma (DLBCL). Although the frequency of loss of MHC expression differs between ABC- and GCB-DLBCL cell of origin (COO) subtypes, distinct genetic alterations and molecular features that affect MHC expression and the composition of immune cells in the tumor microenvironment remain ill-defined. Here, we aimed to uncover the biologic and genomic basis underlying acquired loss of MHC expression.Method: We analyzed biopsies from 347 patients newly diagnosed with de novo DLBCL and uniformly treated with R-CHOP in British Columbia. We performed targeted resequencing, SNP6.0 array and RNAseq for genetic analyses. Immunohistochemical (IHC) staining of MHC-I and -II was performed on tissue microarrays (n=332). COO was assigned by the Lymph2Cx assay in 323 cases (183 GCB, 104 ABC and 36 unclassifiable). Immune cell composition was assessed by IHC, flow cytometry and gene expression profiling (GEP)-based deconvolution of cellular signatures.To experimentally confirm decreased MHC expression induced by EZH2 mutation, we measured surface MHC-I and -II expression on tumor B cells using EZH2Y641/BCL2 mouse model which was previously established (Beguelin et al, Cancer Cell 2013). We also treated human DLBCL cells harboring EZH2 mutation and wild type using EZH2 inhibitor (EPZ-6438), and evaluated their surface MHC-I and -II expression.Results: Loss of MHC-I and -II expression was observed in 43% and 28% of DLBCL cases, respectively. MHC-II loss of expression was significantly associated with the reduction of tumor-infiltrating lymphocytes (TILs), especially CD4 positive T-cells (FOXP3+ cells, PD-1+ cells, and CD4+ naïve and memory T-cells), and cytolytic activity (GZMB and PRF1 mRNA expression) in GCB-DLBCL (all; p<0.001), but not in ABC-DLBCL. MHC-II-negativity was associated with unfavorable prognosis only in GCB-DLBCL (5-year time-to-progression; 59% vs 79%, p=0.007), whereas there was no prognostic impact of MHC-I expression in either subtype, suggesting a link between loss of MHC-II expression and reduced immune surveillance leading to poor prognosis, specifically in GCB-DLBCL.We next performed GEP using RNAseq separately in each COO subtype. Interestingly, only four genes (HLA-DMA, DRA, DPA1 and CD74) were differentially expressed according to MHC-II expression (FDR<0.001) in ABC-DLBCL. By contrast, a total of 641 genes were differentially expressed in GCB-DLBCL. Of importance, a dark zone (DZ) B-cell signature was strongly enriched in MHC-II-negative GCB-DLBCL cases (FDR<0.001), suggesting that MHC-II deficiency defines the tumor originated from DZ of the germinal center.Correlative genetic analysis revealed that, as expected, mutations of CIITA and RFXAP were detected more frequently in MHC-II-negative GCB-DLBCL (p=0.01 and 0.003, respectively). Strikingly, CD83 mutations, which elevate and stabilize MHC-II expression in centrocytes of the light zone (LZ), were significantly enriched in MHC-II positive GCB-DLBCL (p= 0.008), suggesting that these mutations affecting the antigen presentation machinery are selectively acquired in GCB-DLBCL tumors to further reduce and increase the surface MHC-II expression.Genetic analysis also highlighted that EZH2 mutations were most significantly enriched in MHC-II-negative as well as MHC-I-negative GCB-DLBCL cases (both, p<0.001). Indeed, 77% of EZH2 mutated cases demonstrated loss of either MHC-I and/or MHC-II expression on the tumor cells. Notably, we found significantly lower MHC-I and MHC-II expression in high-grade lymphomas of EZH2 mutant Vav-BCL2 transgenic mice compared to EZH2 wildtype control tumors. Furthermore, of potential clinical relevance, in-vitro EZH2 inhibition significantly restored MHC-I and MHC-II gene expression as well as protein expression in EZH2-mutated human DLBCL cells, but not EZH2 wild type tumor cells.Conclusion: Our findings provide important implications for understanding the cancer biology underlying acquired loss of MHC expression. The restoration of MHC expression by EZH2 inhibitors suggests a novel approach of epigenetically enhancing tumor recognition and eradication in combination with immune therapies. DisclosuresSehn:Abbvie: Consultancy, Honoraria; Roche/Genentech: Consultancy, Honoraria; Morphosys: Consultancy, Honoraria; Karyopharm: Consultancy, Honoraria; Lundbeck: Consultancy, Honoraria; TG Therapeutics: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Merck: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria. Connors:Roche Canada: Research Funding; Takeda: Research Funding; Merck: Research Funding; F Hoffmann-La Roche: Research Funding; Cephalon: Research Funding; Seattle Genetics: Honoraria, Research Funding; Amgen: Research Funding; Bayer Healthcare: Research Funding; Bristol Myers-Squibb: Research Funding; Lilly: Research Funding; NanoString Technologies: Patents & Royalties: Named Inventor on a patent licensed to NanoString Technologies, Research Funding; Janssen: Research Funding; Genentech: Research Funding. Gascoyne:NanoString: Patents & Royalties: Named Inventor on a patent licensed to NanoString Technologies. Scott:Roche: Research Funding; Janssen: Research Funding; NanoString: Patents & Royalties: Named Inventor on a patent licensed to NanoString Technologies, Research Funding; Celgene: Consultancy, Honoraria. Steidl:Juno Therapeutics: Consultancy; Roche: Consultancy; Seattle Genetics: Consultancy; Nanostring: Patents & Royalties: patent holding; Bristol-Myers Squibb: Research Funding; Tioma: Research Funding.

A Preliminary Study on the Expression of CD160 on NK Cells and Its Mechanism of Mediating NK Killing Effect

To investigate the expression of CD160 on the surface of human natural killer (NK) cells and its possible relationship with hematological malignancies. CD160 expression on human leukemia cell line NK92 cells was confirmed by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. The proliferation characteristics and cell surface markers of this cell line were determined. Cytotoxicity of NK92 against 2 human myeloid leukemia cell lines, K562 and THP-1 was analyzed ex vivo. CD160 blocking antibody CL1-R2 was employed to clarify its role in NK cell mediated cytolysis. Then, the expression of CD160 on NK cells in peripheral blood from various patients with hematological malignancies were measured by flow cytometry. The mRNA and protein levels of CD160 expressions on NK92 cells were confirmed by RT-PCR and Western blot, respectively. The flow cytometry results demonstrated that the strong positive expression of CD160 could be detected on the NK92 cell surface. NK92 could effectively kill K562 and THP-1 cells, while the cytolysis effect was abrogated in the presence of CD160 blocking antibody CL1-R2. The high levels of HVEM were expressed on both target cells, but the HLA class I molecules were absent on K562. The expression of CD160 on CD3-CD56+ NK cells in peripheral blood from patients with acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL) and allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients was significant lower than that in the normal controls (P<0.05). The cytolysis function of human NK cells is mediated partially by CD160 molecule. The decrease of CD160 expression on NK cells from patients with various hematological malignancies implies that down-regulation of CD160 expression may be a novel mechanism of tumor immune escape.

MS03.05 Integration of Immunotherapy in the Oligometastatic Paradigm

Radiotherapy is a treatment modality commonly used in efforts to manage oligometastatic disease. It is now recognised that radiotherapy does not only directly kill tumour cells, but it also changes the tumour microenvironment, enhancing tumour cell recognition by the immune system, therefore acting as an in situ vaccine. Radiotherapy increases expression of tumour-associated antigens, causes the release of cytokines, stimulates recruitment of dendritic cells and most importantly stimulates the proliferation and priming of cytotoxic CD8+ T-cells in the tumour microenvironment. This immunologic cascade specifically generates activated T-cells able to induce immunogenic cell death directed against cancer cells bearing those antigens. The cellular changes induced by radiotherapy are becoming increasingly important as it is recognised that the majority of patients do not respond to currently available therapies based on immune checkpoint inhibitors. The benefit of those agents is limited to patients who have pre-existing active immune microenvironment that can be re-activated by immunotherapeutic agents. By its ability to overcome some tumour immune escape mechanisms, radiation provides a non-pharmacological and cost-effective approach to potentially improve the systemic response to immune checkpoints inhibitors. In the context of oligometastatic disease, it is unclear what the ideal integration of immunotherapy and radiotherapy should be. Most studies are currently investigating ‘abscopal’ effects with combination radio/immunotherapy strategies in patients with widespread metastases. In the oligometastatic state, does this make sense? Given the local efficacy of radiotherapy, treatment of all macroscopic sites of disease if safe would appear to be a prudent strategy in combination with immunotherapy. Additionally, what is the optimal duration of immunotherapy in this context? What is the ideal timing of radiotherapy, and should it be given upfront or as consolidation? These are some of the issues that will be explored in this short lecture. Oligometastases, abscopal, stereotactic

INDOLEAMINE 2,3 DIOXYGENASE AS AN IMMUNOTHERAPEUTIC TARGET BRINGS A NEW HOPE FOR CANCER PATIENTS

Therapeutic manipulation of immune system in cancer has been an extensive area of research in the field of oncoimmunology. Immunotherapy helps the immune system to combat against cancer. Tumour cells take an edge of immunosuppressive mechanisms and inhibit antitumour immune responses. Indoleamine 2,3 dioxygenase (IDO) is an immunosuppressive enzyme which is involved in tumour immune escape mechanism in various cancers. IDO can degrade the tryptophan into kynurenines and has an ability to enhance the immune tolerance through mammalian target of rapamycin pathway general control nonderepressible 2 (GCN2) pathway and induction of regulatory T (T-regs) cells. IDO-induced T-regs suppress the local immune responses in the tumour microenvironment and promote metastasis. IDO overexpression in various cancers is associated with poor prognosis. Several preclinical and clinical trials have been proceeding and recommend that IDO inhibitor may be an influential tool against a wide range of cancers. IDO inhibitors as adjuvant therapeutic agents may also have clinical implications. Thus, IDO has the potential to be used as an immunotherapeutic target. This review discusses the promising role of IDO in cancer and its implication in immunotherapy.Key words: Breast cancer, colorectal cancer, haematological malignancies, immunotherapy, indoleamine 2,3-dioxygenase, pancreatic cancer, prostate cancer

IL-10 inducible CD8+ regulatory T-cells are enriched in patients with multiple myeloma and impact the generation of antigen-specific T-cells.

Tumor-mediated immunosuppression via regulatory T-cells is a key player among the various immune-escape mechanisms in multiple myeloma. We analyzed the generation, distribution, function and immunophenotype of CD8+CD28- regulatory T-cells in patients with multiple myeloma. Functionality of CD8+CD28- T-cells was assessed by immunological assays using ex vivo generated antigen-specific T-cells from patients with plasma cell dyscrasias and healthy donors. Detailed analysis of distribution, immunophenotype and cytotoxic potential of CD8+CD28- T-cells was performed by flow cytometry and ELISA. We found that the amount of CD8+CD28- T-cells was directly correlated with the suppression of antigen-specific T-cell responses in patients with plasma cell dyscrasia. Analyzing the CD8+CD28- T-cells in detail, increased numbers of these cells were observed in the bone marrow (i.e., tumor microenvironment) of patients with plasma cell dyscrasia. Furthermore, we identified the expression of lymphocyte function-associated antigen 1 (LFA-1) as a marker of immunosuppression and defined the CD8+CD28-CD57+LFA-1high population as the relevant immunosuppressive compartment. These regulatory T-cells act as immunosuppressors via soluble factors and incubation with IL-10 augmented their immunosuppressive capacity. The immunosuppressive regulatory network of IL-10 and the CD8+CD28-CD57+LFA-1high regulatory T-cells show unique characteristics and contribute to the tumor immune escape mechanism in patients with multiple myeloma.

Urothelial bladder cancer may suppress perforin expression in CD8+ T cells by an ICAM-1/TGFβ2 mediated pathway.

The immune system plays a significant role in urothelial bladder cancer (UBC) progression, with CD8+ T cells being capable to directly kill tumor cells using perforin and granzymes. However, tumors avoid immune recognition by escape mechanisms. In this study, we aim to demonstrate tumor immune escape mechanisms that suppress CD8+ T cells cytotoxicity. 42 patients diagnosed with UBC were recruited. CD8+ T cells from peripheral blood (PB), sentinel nodes (SN), and tumor were analyzed in steady state and in vitro-stimulated conditions by flow cytometry, RT-qPCR, and ELISA. Mass spectrometry (MS) was used for identification of proteins from UBC cell line culture supernatants. Perforin was surprisingly found to be low in CD8+ T cells from SN, marked by 1.8-fold decrease of PRF1 expression, with maintained expression of granzyme B. The majority of perforin-deficient CD8+ T cells are effector memory T (TEM) cells with exhausted Tc2 cell phenotype, judged by the presence of PD-1 and GATA-3. Consequently, perforin-deficient CD8+ T cells from SN are low in T-bet expression. Supernatant from muscle invasive UBC induces perforin deficiency, a mechanism identified by MS where ICAM-1 and TGFβ2 signaling were causatively validated to decrease perforin expression in vitro. Thus, we demonstrate a novel tumor escape suppressing perforin expression in CD8+ T cells mediated by ICAM-1 and TGFβ2, which can be targeted in combination for cancer immunotherapy.

Regulatory T cell-targeted hybrid nanoparticles combined with immuno-checkpoint blockage for cancer immunotherapy

Immunosuppression in tumor microenvironments induced by regulatory T (Treg) cells is regarded a critical mechanism of tumor immune escape and poses a major impediment to cancer immunotherapy. In this study, we developed tLyp1 peptide-conjugated hybrid nanoparticles for targeting Treg cells in the tumor microenvironment. The tLyp1 peptide-modified hybrid nanoparticles presented good stability and effective targeting to Treg cells, and they enhanced the effect of imatinib in downregulating Treg cell suppression through inhibition of STAT3 and STAT5 phosphorylation. In addition, an in vivo study revealed high tumor accumulation of the hybrid nanoparticle. Specifically, prolonged survival rate, enhanced tumor inhibition, reduced intratumoral Treg cells, and elevated intratumoral CD8+ T cells against tumor were observed when combined with checkpoint-blockade by using anti-cytotoxic T-lymphocyte antigen-4 antibody. This study provided groundwork for a repertoire of nanoparticle-based drugs for targeting and modulating Treg cell function in the tumor microenvironment and for improving antitumor immunotherapy.

Immune Response against ALK in Children with ALK-Positive Anaplastic Large Cell Lymphoma.

Patients with anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALCL) mount a humoral and cellular immune response against ALK. More than 90% of children and adolescents with ALK-positive ALCL have detectable anti-ALK antibodies in serum or plasma, and the antibody titer inversely correlates with the risk of relapse. ALK-specific CD8 and CD4 T cell responses have been described in patients with ALK-positive ALCL. Vaccination with ALK DNA led to protection against lymphoma growth in a murine model. Collectively, these data suggest that the ALK-specific immune response is involved in the control of the disease. The characteristics of the humoral and cellular immune response against ALK as well as tumor immune escape mechanisms have been increasingly investigated. However, tumor and host factors contributing to the individual immune response against ALK are still largely unknown. Depending on the individual strength of the immune response and its determinants, individualized immunological approaches might be appropriate for the consolidation of ALCL patients. Strategies such as ALK vaccination could be effective for those with a pre-existing anti-tumor immunity, while an allogeneic blood stem cell transplantation or check-point inhibition could be effective for others.

Implementation of immunotherapy in the treatment of advanced non-small cell lung cancer (NSCLC).

Mechanisms of tumor immune surveillance and immune escape have been recently elucidated and led to the development of a new therapeutic field in oncology, that of immunotherapy. Immunotherapy aims to reactivate the immune system against cancer. Neoplasias like non-small cell lung cancer (NSCLC) are of particular interest and clinical studies with immunotherapeutic agents have shown significant survival benefit. Several agents have gained corresponding regulatory approvals. In particular, nivolumab, pembrolizumab and atezolizumab have been approved for second-line treatment of NSCLC, pembrolizumab is the only immune checkpoint inhibitor that has been approved in the first-line treatment and durvalumab is approved in the locally advanced disease. In this review, we aim to present the implementation of immunotherapy in the treatment of advanced NSCLC. We will discuss not only the approved regimens but also the future perspectives, the serious adverse events such as hyperprogression and the possible predictive markers that will aid the selection of the patients that will benefit from immunotherapy.

The transition from HLA-I positive to HLA-I negative primary tumors: the road to escape from T-cell responses

MHC/HLA class I loss in cancer is one of the main mechanisms of tumor immune escape from T-cell recognition and destruction. Tumor infiltration by T lymphocytes (TILs) and by other immune cells was first described many years ago, but has never been directly and clearly linked to the destruction of HLA-I positive and selection of HLA-I negative tumor cells. The degree and the pattern of lymphocyte infiltration in a tumor nest may depend on antigenicity and the developmental stages of the tumors. In addition, it is becoming evident that HLA-I expression and tumor infiltration have a direct correlation with tumor tissue reorganization. We observed that at early stages (permissive Phase I) tumors are heterogeneous, with both HLA-I positive and HLA-negative cancer cells, and are infiltrated by TILs and M1 macrophages as a part of an active anti-tumor Th1 response. At later stages (encapsulated Phase II), tumor nests are mostly HLA-I negative with immune cells residing in the peri-tumoral stroma, which forms a granuloma-like encapsulated tissue structure. All these tumor characteristics, including tumor HLA-I expression pattern, have an important clinical prognostic value and should be closely and routinely investigated in different types of cancer by immunologists and by pathologists. In this review we summarize our current viewpoint about the alterations in HLA-I expression in cancer and discuss how, when and why tumor HLA-I losses occur. We also provide evidence for the negative impact of tumor HLA-I loss in current cancer immunotherapies, with the focus on reversible ('soft') and irreversible ('hard') HLA-I defects.

Increased Coexpression of PD-1, TIGIT, and KLRG-1 on Tumor-Reactive CD8+ T Cells During Relapse after Allogeneic Stem Cell Transplantation

Allogeneic stem cell transplantation (allo-SCT) can be a curative treatment for patients with a hematologic malignancy due to alloreactive T cell responses recognizing minor histocompatibility antigens (MiHA). Yet tumor immune escape mechanisms can cause failure of T cell immunity, leading to relapse. Tumor cells display low expression of costimulatory molecules and can up-regulate coinhibitory molecules that inhibit T cell functionality on ligation with their counter-receptors on the tumor-reactive T cells. The aim of this explorative study was to evaluate immune checkpoint expression profiles on T cell subsets and on cytomegalovirus (CMV)- and/or MiHA-reactive CD8+ T cells of allo-SCT recipients using a 13-color flow cytometry panel, and to correlate these expression patterns to clinical outcomes. MiHA-reactive CD8+ T cells exhibited an early differentiated CD27++/CD28++ phenotype with low KLRG-1 and CD57 expression. These T cells also displayed increased expression of PD-1, TIM-3, and TIGIT compared with total effector memory T cells and CMV-specific CD8+ T cells in healthy donors and allo-SCT recipients. Remarkably, high coexpression of PD-1, TIGIT, and KLRG-1 on MiHA-reactive CD8+ T cells was associated with relapse after allo-SCT. Taken together, these findings indicate that MiHA-specific CD8+ T cells of relapsed patients have a distinctive coinhibitory expression signature compared with patients who stay in remission. This phenotype may serve as a potential monitoring tool in patients. Moreover, these findings suggest that PD-1 and TIGIT play important roles in regulating T cell-mediated tumor control, providing a rationale for immunotherapy with blocking antibodies to treat relapse after allo-SCT.

TAP1 down-regulation elicits immune escape and poor prognosis in colorectal cancer

ABSTRACTThe anti-tumor immune response has been shown to be of great prognostic importance in colorectal cancer (CRC) and so has the tumors ability for immune evasion. Our aim of this study was to investigate tumor factors that influence immunity. We used a gene expression array to search for potential mechanisms of tumor immune escape.One candidate gene identified was TAP1, involved in antigen presentation by MHC class I. TAP1 protein expression was evaluated by immunohistochemistry in 436 CRC patients of the Colorectal Cancer in Umeå Study cohort. We found a significant association between a downregulated expression of TAP1 and low infiltration of various subtypes of lymphocytes as well as macrophages. A downregulated expression of TAP1 was further found to be independent of molecular characteristics, suggesting TAP1 down-regulation to reach beyond the well described highly immunogenic MSI CRCs. A low expression of TAP1 was also significantly associated with poor prognosis in patients with CRC, a result that stayed significant in tumor front of early stage tumors (stage I-II) through multivariable analyses. Furthermore, we found that TAP1 expression was inversely correlated with methylation at sites in close proximity to the promoter region.In summary, our results show down-regulation of TAP1 to be a general mechanism of tumor immune escape in CRC and a poor prognostic factor in stage I-II CRC patients. We also suggest that methylation of the TAP1 gene may be a putative mechanism for TAP1 downregulation.

Immunotherapies for head and neck squamous cell carcinomas

The Head and neck squamous cell carcinoma (HNSCC) is a group of heterogeneous diseases. Patients with HNSCC demonstrate poor prognosis and survival time with standard therapy, especially in patients with advanced HNSCC. Recurrence and metastasis have not yet been effectively controlled. The immune profile in HNSCC, whether caused by carcinogen exposure or human papillomavirus (HPV), showed significantly immunosuppression. With the understanding of the complex interaction between tumor and immune system and immune escape mechanism of HNSCC, new immunotherapies have been generating. This article will summarize the immunological mechanism and immune therapy of HNSCC currently..

Abstract 5578: Small molecule modulators to understand the role of IDO1 and TDO2 in cancer

Abstract Introduction: Tumor immune escape mechanisms have been established as suitable targets for cancer therapy. Among these, tryptophan catabolism plays a central role in creating an immunosuppressive environment, leading to tolerance to potentially immunogenic tumor antigens. Tryptophan catabolism is initiated by either indoleamine 2,3-dioxygenase (IDO1/2) or tryptophan 2,3-dioxygenase 2 (TDO2), resulting in biostatic tryptophan starvation and l-kynurenine production. Recent literature has shown that IDO1 and TDO2 are expressed in multiple tumors, including solid tumors and play key roles in tumor progression other than immune escape. It has also been shown that IDO1 and TDO2 play distinct roles in driving the downstream effectors suggesting that their roles are perhaps non-redundant. Therefore, we developed series of novel small molecule modulators against IDO1 and TDO2 to understand their role in disease biology for multiple indications including cancer, depression and autoimmune disorders. Methods: Rational design approaches were used to design novel IDO1 and TDO2 specific modulators; Potency of these inhibitors was assessed in the in vitro assays using purified IDO1 and TDO2 enzymes and in IDO1 and TDO2 over-expressing HEK293T cells by measuring the formation of kynurenine. Results: In the in vitro biochemical assay using purified human TDO2, one of the NCEs from inhibitor series showed an IC50 of 0.09 μM against TDO2. Against purified human IDO1, this compound was inactive up to 30 μM, thereby showing &amp;gt;300-fold selectivity against IDO1. This TDO2 inhibitory activity translated well in TDO2-overexpressing HEK293 cells and, these NCEs inhibited kynurenine formation with an EC50 of ~2.5 μM. A second chemical series showed comparable dual inhibition of IDO1 and TDO2 activity. One of the molecules from this series showed IC50 of 0.2 and 0.08 μM in the biochemical assay and 1.7 and 0.8 μM in the cell based assay against IDO1 and TDO2, respectively. In addition, another series of NCEs showed strong activation of IDO1 and TDO2 activity. As compared to untreated control, formation of kynurenine was increased in a dose-dependent manner as observed by increase in fluorescence up to of 3-10 folds. One of the compounds from this series showed an EC50 of ~20- 30 μM in the biochemical assay as well as in 293T-based assay. Further mechanistic studies to understand the immune modulatory activity of these selective TDO2 modulators is underway. These tool compounds are being further optimized for potency and ADME properties to be developed as potential drug candidates. Conclusion: To our knowledge such IDO1 and TDO2 specific small molecule activators have not been reported earlier. Therefore, these activators and inhibitors would serve as useful tool compounds in understanding the specific role(s) of IDO1 and TDO2 in disease biology and would also provide us the opportunity to target this pathway for various diseases, including cancer. Citation Format: Shivani Rao Garapaty, Dhanalakshmi Sivanandhan, Guru Pavan Kumar Seerapu, Surendra Naidu, Shalini Chakelam, Pradeep Nagaraj, Reshma Das, Saravanan Vadivelu, Pravin Iyer, Chandrika Mulakala, Kannan Murugan, Somnath Mondal, Anjali Gautam, Saravanan Kandan, Manish Kumar Thakur, Sridharan Rajagopal, Sriram Rajagopal. Small molecule modulators to understand the role of IDO1 and TDO2 in cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5578. doi:10.1158/1538-7445.AM2017-5578

Recent insights into the implications of metabolism in plasmacytoid dendritic cell innate functions: Potential ways to control these functions

There are more and more data concerning the role of cellular metabolism in innate immune cells, such as macrophages or conventional dendritic cells. However, few data are available currently concerning plasmacytoid dendritic cells (PDC), another type of innate immune cells. These cells are the main type I interferon (IFN) producing cells, but they also secrete other pro-inflammatory cytokines (e.g., tumor necrosis factor or interleukin [IL]-6) or immunomodulatory factors (e.g., IL-10 or transforming growth factor-β). Through these functions, PDC participate in antimicrobial responses or maintenance of immune tolerance, and have been implicated in the pathophysiology of several autoimmune diseases, as well as in tumor immune escape mechanisms. Recent data support the idea that the glycolytic pathway (or glycolysis), as well as lipid metabolism (including both cholesterol and fatty acid metabolism) may impact some innate immune functions of PDC or may be involved in these functions after Toll-like receptor (TLR) 7/9 triggering. The kinetics of glycolysis after TLR7/9 triggering may differ between human and murine PDC. In mouse PDC, metabolism changes promoted by TLR7/9 activation may depend on an autocrine/paracrine loop, implicating type I IFN and its receptor IFNAR. This could explain a delayed glycolysis in mouse PDC. Moreover, PDC functions can be modulated by the metabolism of cholesterol and fatty acids. This may occur via the production of lipid ligands that activate nuclear receptors (e.g., liver X receptor [LXR]) in PDC or through limiting intracellular cholesterol pool size (by statin or LXR agonist treatment) in these cells. Finally, lipid-activated nuclear receptors (i.e., LXR or peroxisome proliferator activated receptor) may also directly interact with pro-inflammatory transcription factors, such as NF-κB. Here, we discuss how glycolysis and lipid metabolism may modulate PDC functions and how this may be harnessed in pathological situations where PDC play a detrimental role.

Redirected Primary Human Chimeric Antigen Receptor Natural Killer Cells As an "Off-the-Shelf Immunotherapy" for Improvement in Cancer Treatment.

Primary human natural killer (NK) cells recognize and subsequently eliminate virus infected cells, tumor cells, or other aberrant cells. However, cancer cells are able to develop tumor immune escape mechanisms to undermine this immune control. To overcome this obstacle, NK cells can be genetically modified to express chimeric antigen receptors (CARs) in order to improve specific recognition of cancer surface markers (e.g., CD19, CD20, and ErbB2). After target recognition, intracellular CAR domain signaling (CD3ζ, CD28, 4-1BB, and 2B4) leads to activation of PI3K or DNAX proteins (DAP10, DAP12) and finally to enhanced cytotoxicity, proliferation, and/or interferon γ release. This mini-review summarizes both the first preclinical trials with CAR-engineered primary human NK cells and the translational implications for “off-the-shelf immunotherapy” in cancer treatment. Signal transduction in NK cells as well as optimization of CAR signaling will be described, becoming more and more a focal point of interest in addition to redirected T cells. Finally, strategies to overcome off-target effects will be discussed in order to improve future clinical trials and to avoid attacking healthy tissues.

The Combination of New Immunotherapy and Radiotherapy: A N ew Potential Treatment for Locally Advanced Non-Small Cell Lung Cancer.

Lung cancer is the main reason of cancer death worldwide. About 30% of non-small-cell lung cancer (NSCLC) cases are diagnosed with locally advanced disease (stage III). This is a mixed population including patients who have far more extensive and bulky disease than others. Management of these patients continue to be a challenge; frequently, patients have both local recurrence and distant metastases in this stage and the prognosis is very poor with a 5-year overall survival estimated between 3% and 7% for inoperable disease. The standard treatment for these patients is concurrent chemo-radiotherapy (CRT) improving survival when compared to sequential combination as shown in several metanalysis. Recently, immune-therapies, including checkpoint inhibitor, such as monoclonal antibodies against programmed death receptor 1 (PD-1) and programmed death ligand 1 (PD-L1), have shown to enhance survival compared to chemotherapy in patients with advanced NSCLC. The integration of radiotherapy with immunotherapy is a conceptually promising strategy and several preclinical experiments have further developed the rationale for combining them. Radiotherapy has the capacity to overcome a lot of tumor immune escape mechanisms through the liberation of immunogenic private antigens showing a better local control and augmenting the immune response of systemic agents. This manuscript discusses the potential clinical interest for the combination of radiation and immunotherapy in locally advanced NSCLC.

Deficient necroptosis pathway as a negative prognostic factor in acute myeloid leukemia.

11611 Background: Necroptosis is a type of necrotic cell death involving several genes transcription and activation of molecular mechanisms as death receptors, interferon, toll-like receptors, intracellular RNA and DNA sensors.The process is leading by the family of receptor-interacting protein kinase ( RIPK3, RIPK2, RIPK1) and the MLKL substrate. Losses of RIPK3 or MLKL, as well as deficiency in apoptosis, could allow tumor cells to escape the immunomediated cells death (ICD). Methods: We performed SNP Arrays (Cytoscan HD and SNP 6.0, Affymetrix) on a cohort of 300 non-M3 AML patients at diagnosis and we analyzed the Overall Survival (OS) of our patients with deficiency on necroptosis pathways. Survival was analyzed with Kaplan-Mayer method and Log-Rank test. We further analyze the relevance of different prognostic factors by the use of COX-Hazard Ratio statistical analysis. Results: We find that 18 patients presented a loss of RIPK1 or MLKL (nobody presented losses in RIPK3/RIPK2) and 13/18 patients were older than 65 years old. The Overall Survival (OS) of patients with alterations in these genes is significantly lower than control group, with a median OS of 3 vs 6 month respectively (p&lt;.0.001). With Fisher Exact Test we further demonstrate that copy number loss of RIPK1 or MLKL are associate to loss of TP53 or FANCAgenes, complex karyotype and advanced age. COXHR model with RIPK1 or MLKL loss, BRACA1 loss, TP53 mutation, FANCA loss, secondary disease and diagnosis karyotype considered as categorical variable shows that necroptosis deficiency (HR 1.98, CI 95% 1.04-3.78), TP53mutation , and secondary AML are independent negative prognostic factors in an optimal model. Conclusions: Our study shows that losses in necroptosis pathways are an uncommon alteration in AML, prevalent in old population. Moreover, we hypothesize that the loss of genes involved in necroptosis could be a real mechanism of tumor immune-escape and could be a rational to select patients that have high probability to be resistant at chemotherapy promoting ICD mechanism. Acknowledgment: ELN,AIL,AIRC, progetto Regione-Università 2010-12, FP7 NGS-PTL project,HARMONY.

Natural Killer Group 2D Ligand Depletion Reconstitutes Natural Killer Cell Immunosurveillance of Head and Neck Squamous Cell Carcinoma.

Head and neck squamous cell carcinoma (HNSCC) is a highly heterogeneous and aggressive tumor originating from the epithelial lining of the upper aero-digestive tract accounting for 300,000 annual deaths worldwide due to failure of current therapies. The natural killer group 2D (NKG2D) receptors on natural killer (NK) cells and several T cell subsets play an important role for immunosurveillance of HNSCC and are thus targeted by tumor immune evasion strategies in particular by shedding of various NKG2D ligands (NKG2DLs). Based on plasma and tumor samples of 44 HNSCC patients, we found that despite compositional heterogeneity the total plasma level of NKG2DLs correlates with NK cell inhibition and disease progression. Strikingly, based on tumor spheroids and primary tumors of HNSCC patients, we found that NK cells failed to infiltrate HNSCC tumors in the presence of high levels of NKG2DLs, demonstrating a novel mechanism of NKG2DL-dependent tumor immune escape. Therefore, the diagnostic acquisition of the plasma level of all NKG2DLs might be instrumental for prognosis and to decipher a patient cohort, which could benefit from restoration of NKG2D-dependent tumor immunosurveillance. Along these lines, we could show that removal of shed NKG2DLs (sNKG2DLs) from HNSCC patients’ plasma restored NK cell function in vitro and in individual patients following surgical removal of the primary tumor. In order to translate these findings into a therapeutic setting, we performed a proof-of-concept study to test the efficacy of adsorption apheresis of sNKG2DLs from plasma after infusion of human MICA in rhesus monkeys. Complete removal of MICA was achieved after three plasma volume exchanges. Therefore, we propose adsorption apheresis of sNKG2DLs as a future preconditioning strategy to improve the efficacy of autologous and adoptively transferred immune cells in cellular cancer immunotherapy.

Predictive and prognostic role of serum neopterin and tryptophan breakdown in prostate cancer.

The γ‐interferon‐induced enzymes indoleamine 2,3‐dioxygenase and GTP‐cyclohydrolase are key players in tumor immune escape mechanisms. We quantified serum levels of neopterin and tryptophan breakdown (tryptophan, kynurenine, and kynurenine‐to‐tryptophan ratio) in addition to prostate‐specific antigen (PSA) in newly diagnosed prostate cancer (PCa) patients (n = 100) before radical prostatectomy (RP) as well as at time of biochemical recurrence (BCR) after RP (n = 50) in comparison to healthy men (n = 49). Effects of biomarkers on the risk of PCa diagnosis on transrectal biopsy, worse histopathological characteristics of the RP specimens, and cancer‐specific survival (CSS) after BCR were investigated. Neopterin (hazard ratio [HR], 2.46; 95% confidence interval [CI], 1.08–5.61; P = 0.032) and kynurenine (HR, 2.93; 95% CI, 1.26–6.79; P = 0.012) levels were univariately associated with CSS. When adjusted for other biomarkers, only neopterin remained an independent predictor of CSS (HR, 2.56; 95% CI, 1.07–6.12; P = 0.035). Only PSA was associated with an increased risk of PCa diagnosis on biopsy, univariately (odds ratio, 3.14; 95% CI, 1.68–5.88; P < 0.001) as well when adjusted for other biomarkers (odds ratio, 3.29; 95% CI, 1.70–6.35; P < 0.001). Moreover, only preoperative PSA was able to predict positive surgical margin (area under the receiver operating characteristic curve [AUC] = 0.71; 95% CI, 0.59–0.82; P = 0.001), higher Gleason score (AUC = 0.75; 95% CI, 0.66–0.85; P < 0.001) and extraprostatic involvement (AUC = 0.79; 95% CI, 0.69–0.88; P < 0.001) at RP specimens, respectively. Although serum neopterin and tryptophan breakdown cannot be considered as biomarkers in detecting PCa or in predicting worse final pathological findings, neopterin levels are useful for stratifying patients into different prognostic groups after BCR.