Host Antitumor Immune Response Research Articles

PD-1/PD-L1 Blockade Therapy in Advanced Non-Small-Cell Lung Cancer: Current Status and Future Directions.

The use of immune checkpoint inhibitors (ICIs) has become one of the most promising approaches in the field of cancer therapy. Unlike the current therapies that target tumor cells, such as chemotherapy, radiotherapy, or targeted therapy, ICIs directly restore the exhausted host antitumor immune responses mediated by the tumors. Among multiple immune modulators identified, the programmed cell death protein 1 (PD-1)/programmed cell death protein ligand 1 (PD-L1) axis leading to the exhaustion of T-cell immunity in chronic infections and tumors has been widely investigated. Therefore, blocking antibodies targeting PD-1 or PD-L1 have been developed and approved for the treatment of various advanced cancers, including non-small-cell lung cancer (NSCLC), making them the most successful ICIs. Compared with chemotherapy or radiotherapy, PD-1/PD-L1 blockade therapy significantly improves the durable response rate and prolongs long-term survival with limited adverse effects in both monotherapy and combination therapy for advanced NSCLC. However, extensive challenges exist for further clinical applications, such as a small fraction of benefit population, primary and acquired resistance, the lack of predictive and prognostic biomarkers, and treatment-related adverse effects. In this article, we summarize the latest clinical applications of PD-1/PD-L1 blockade therapy in advanced NSCLC worldwide, as well as in China, and discuss the bottlenecks related to the use of this therapy in clinical practice. An exploration of the underlying mechanism of PD-1/PD-L1 blockade therapy and biomarker identification will maximize the application of ICIs in advanced NSCLC and facilitate bedside-to-bench studies in cancer immunotherapy as well. IMPLICATIONS FOR PRACTICE: Immune checkpoint inhibitors (ICIs) targeting programmed cell death protein 1 (PD-1) and programmed cell death protein ligand 1 (PD-L1) display apparent benefits for the treatment of advanced non-small-cell lung cancer (NSCLC). However, the clinical applications of these therapies are challenged by the limited benefit population with additional high economic burden and adverse events. This review discusses the bottlenecks of ICI therapy in clinical practice and provides appropriate guidance in the development of predictive biomarkers, the establishment of the criteria for combining PD-1/PD-L1 blockade therapy with the existing therapies, and the management of adverse events observed both in monotherapy and combination therapy, which will help maximize the applications of ICIs in advanced NSCLC.

Scoring System for Tumor-Infiltrating Lymphocytes and Its Prognostic Value for Gastric Cancer.

The tumor microenvironment (TME) is the internal environment of malignant tumor progression, and the host antitumor immune response and normal tissue destruction occur in the TME. Tumor-infiltrating lymphocytes (TIL) is a crucial component of the TME and reflect the host antitumor immune response. The purpose of this study was to discuss the methodology for TIL evaluation and assess the prognostic value of TIL in gastric cancer. In total, we reviewed 1,033 gastrectomy cases between 2002 and 2008 at the Third Affiliated Hospital of Soochow University. To understand the prognostic value of TIL in gastric cancer (GC), TIL were assessed by optical microscopy, and verified by immunohistochemistry. There is no current consensus on TIL scoring in GC. In this study, we discussed a TIL evaluation system that includes an analysis of the amount and percentage of TIL in a tumor. Ultimately, 439 (52.7%) cases showed high levels of TIL and 394 (47.3%) cases had low levels. There was a statistically significant relationship among TIL, tumor size, histological grade, LN metastasis, nerve invasion, tumor thrombus, pTN stage, and WHO subtypes (p < 0.001, respectively). TILhi was a positive significant predictor of overall survival (OS) in Kaplan–Meier survival analysis (P < 0.001) and multivariate Cox regression analysis (HR = 0.431, 95% CI: 0.347–0.534, P < 0.001). After surgery, patients with malignant tumors underwent chemoradiotherapy according to standard therapeutic guidelines based on TNM stage. The TNM scoring system cannot reflect the full information of TME; therefore, TIL can be used as a diagnostic supplement. We constructed a nomogram model that showed more predictive accuracy for OS than pTN stage. In summary, this study proves that high levels of TIL are associated with a positive prognosis and that TIL reflect the protective host antitumor immune response.

PEGylated reduced-graphene oxide hybridized with Fe3O4 nanoparticles for cancer photothermal-immunotherapy.

Photoimmunotherapy has attracted much attention recently for the treatment of metastatic tumors. The development of smart nanocomposites for imaging-guided therapies is needed to improve the efficacy of cancer treatment. Herein, a PEGylated nanocomposite was developed for photothermal-immunotherapy. In particular, this nanocomposite was formulated by hybridizing Fe3O4 nanoparticles (FNPs) with reduced-graphene oxide (rGO) through electrostatic interaction, modified by PEG-NH2 on the surface of FNPs/rGO. The FNPs/rGO-PEG nanocomposites are excellent agents for photothermal therapy (PTT) under irradiation by an 805 nm laser. This nanocomposite could promote the activity of the host antitumor immune response efficiently because of the reduction of tumor-associated macrophages by the incorporation of FNPs. In our experiments, we observed FNPs/rGO-PEG based PTT induced immunogenic cell death accompanied by the release of danger-associated molecular patterns. We also found that FNPs/rGO-PEG + laser irradiation of animal tumors could activate dendritic cells (DCs) in tumor draining lymph nodes. In vivo antitumor studies revealed that FNPs/rGO-PEG nanocomposites, when combined with laser irradiation, could result in desirable photothermal effects and destroy primary tumors. Moreover, intratumoral injection of FNPs/rGO-PEG nanocomposites into 4T1 orthotopic mouse breast tumors, in combination with near-infrared laser irradiation, significantly increased the median survival time of tumor-bearing animals. FNPs/rGO-PEG nanocomposites could also be used for magnetic resonance imaging, which may lead to a MRI-guided photothermal-immunotherapy for metastatic cancers. This study could lead to a cancer treatment strategy that combines PTT with immunotherapies using FNPs/rGO-PEG nanocomposites.

Intercellular transfer of HLA-G: its potential in cancer immunology.

Intercellular protein transfer between cancer cells and immune cells is a very common phenomenon that can affect different stages of host antitumor immune responses. HLA‐G, a non‐classical HLA class I antigen, has been observed to be widely expressed in various malignancies, and its immune‐suppressive functions have been well recognised. HLA‐G expression in cancer cells can directly mediate immune tolerance by interacting with inhibitory receptors such as ILT2 and ILT4 expressed on immune cells. Moreover, a network of multiple directional intercellular transfers of HLA‐G among cancer cells and immune cells through trogocytosis, exosomes and tunnelling nanotubes provides malignant cells with an alternative ploy for antigen sharing and induces more complex heterogeneity, to modulate immune responses, ultimately leading to immune evasion, therapy resistance, disease progression and poor clinical outcome. Herein, we discuss the relative aspects of the intercellular transfer of HLA‐G between tumor cells and immune cells and its potential use in tumor immunology research and translational cancer therapy.

Characteristics of Immune Response to Tumor‐Associated Antigens and Immune Cell Profile in Patients With Hepatocellular Carcinoma

Host antitumor immune responses may be different between hepatocellular carcinoma (HCC) caused by metabolic disorders and HCC associated with hepatitis virus infection. In this study, we examined the immune response of tumor-associated antigen (TAA)-specific T cells and immune cell profile in patients with HCC separated by cause. Thirty-two patients with hepatitis B virus (HBV)-related HCC, 42 patients with hepatitis C virus-related HCC, and 18 patients with nonalcoholic steatohepatitis (NASH)-related HCC were analyzed. The frequencies of TAA-specific T cells, the expression levels of surface markers on each immune cell, and the expression of each TAA in HCC tissue were measured. The immune response to TAA and immune cell profile were markedly different among the three groups. The immune response to TAA in the NASH-related HCC group was weaker than the responses in the other two groups. In patients with NASH-related HCC, the frequencies of effector regulatory T cells (eTregs) and cluster of differentiation 8-positive (CD8+ ) T cells strongly expressing cytotoxic T-lymphocyte antigen (CTLA)-4 were high. The frequency of CD8+ T cells strongly expressing programmed cell death 1 was the highest in patients with HBV-related HCC. Among these immune cell profiles, the frequencies of C-X-C motif chemokine receptor 3+ eTregs and CTLA-4+ CD8+ T cells were inversely correlated with the strength of the TAA-specific T-cell immune response, and the restoration of TAA-specific T-cell responses by anti-CTLA-4 antibody was observed. Conclusion: The immune response to TAA were markedly different among the three groups, and a correlation with the immune cell profile was observed, suggesting that development of immunotherapy based on the etiology of HCC may lead to more effective treatment outcomes.

The Role of Yes-Associated Protein (YAP) in Regulating Programmed Death-Ligand 1 (PD-L1) in Thoracic Cancer.

The programmed death-ligand 1(PD-L1)/PD-1 pathway is an immunological checkpoint in cancer cells. The binding of PD-L1 and PD-1 promotes T-cell tolerance and helps tumor cells escape from host immunity. Immunotherapy targeting the PD-L1/PD-1 axis has been developed as an anti-cancer therapy and used in treating advanced human non-small cell lung cancer (NSCLC) and malignant pleural mesothelioma (MPM). Yes-associated protein (YAP) is a key mediator of the Hippo/YAP signaling pathway, and plays important roles in promoting cancer development, drug resistance and metastasis in human NSCLC and MPM. YAP has been suggested as a new therapeutic target in NSCLC and MPM. The role of YAP in regulating tumor immunity such as PD-L1 expression has just begun to be explored, and the correlation between YAP-induced tumorigenesis and host anti-tumor immune responses is not well known. Here, we review recent studies investigating the correlation between YAP and PD-L1 and demonstrating the mechanism by which YAP regulates PD-L1 expression in human NSCLC and MPM. Future work should focus on the interactions between Hippo/YAP signaling pathways and the immune checkpoint PD-L1/PD-1 pathway. The development of new synergistic drugs for immune checkpoint PD-L1/PD-1 blockade in NSCLC and MPM is warranted.

Where does PD-1 blockade fit in HL therapy?

Genetic alterations of the PD-L1/PD-L2 locus on chromosome 9p24.1 are a defining biological feature of classical Hodgkin lymphoma (HL). The resulting programmed death-ligand 1 (PD-L1) expression on Hodgkin Reed-Sternberg cells as well as the PD-L1 expressed in the HL microenvironment result in an ineffective host antitumor immune response and make HL a ripe target for programmed cell death-1 (PD-1) blockade. Anti-PD-1 antibody monotherapy has been effective and well tolerated in patients with relapsed or refractory (rel/ref) HL, with the majority of patients experiencing an objective response (approximately two-thirds of patients) and a median duration of response of 16.6 months in the study with the longest follow-up. Based on these data, nivolumab and pembrolizumab were approved by the US Food and Drug Administration (FDA) for the treatment of advanced rel/ref HL. Evidence has emerged that patients with HL benefit from continued PD-1 blockade beyond disease progression according to traditionally defined response criteria, and that the addition of, or switch to, chemotherapy after anti-PD-1 antibody failure can potentially re-induce clinical response. Subsequent studies have evaluated novel anti-PD-1-based combination regimens as well as the use of anti-PD-1 antibody therapy earlier in the course of a HL patient's therapy, including first salvage therapy for rel/ref disease (eg, nivolumab plus brentuximab vedotin) and even first-line treatment (eg, nivolumab added to doxorubicin, vinblastine, dacarbazine chemotherapy). The current role of PD-1 blockade in HL is as monotherapy in patients with advanced rel/ref disease, but the results of ongoing studies and the evolving treatment landscape in HL will determine the role of PD-1 blockade in the future.

Nivolumab Combined with Brentuximab Vedotin for Relapsed/Refractory Primary Mediastinal Large B-Cell Lymphoma: Preliminary Results from the Phase 2 CheckMate 436 Trial

Nivolumab Combined with Brentuximab Vedotin for Relapsed/Refractory Primary Mediastinal Large B-Cell Lymphoma: Preliminary Results from the Phase 2 CheckMate 436 Trial

Mechanism and prognostic value of indoleamine 2,3‐dioxygenase 1 expressed in hepatocellular carcinoma

Indoleamine 2,3‐dioxygenase 1 (IDO1) is a tryptophan‐metabolizing enzyme that is widely distributed in normal or malignant tissues and contributes to immunologic tolerance and immune escape. However, in hepatocellular carcinoma (HCC), the characteristics and mechanism of IDO1 expression have not been well defined. In this study, IDO1 expression in tumor cells (T‐IDO1) was frequently detected (109/112) by immunohistochemistry in formalin‐fixed paraffin‐embedded specimens from HCC patients, and the expression patterns were mostly focal (102/109). Expression of T‐IDO1 was significantly associated with the infiltration of CD8+ T cells (P = .043), as well as younger age (<50 years old, P = .02). It was also found that IDO1 had diffuse expression in inflammatory cells in all specimens, which were defined as antigen‐presenting cells. Significant correlations among IDO1,IFNG, and CD8A transcriptional levels were observed in freshly resected HCC specimens; moreover, no constitutive IDO1 expression was detected in HCC cell lines until stimulated by interferon‐γ through the JAK2‐STAT1 signaling pathway, but not type I interferon. Survival analyses showed that increased T‐IDO1 and CD8+ T cell infiltration were significantly associated with superior overall survival (OS) (T‐IDO1, P = .003; CD8+ T cells, P = .004), and T‐IDO1 expression is an independent prognosis factor in both OS and disease‐free survival (OS, P = .007; disease‐free survival, P = .044). These findings indicated that T‐IDO1 expression in HCC is common and is dominantly driven by the host antitumor immune response, which is a favorable prognostic factor in HCC.

Gene expression profile of peripheral blood mononuclear cells may contribute to the identification and immunological classification of breast cancer patients.

It has been reported that the gene expression profile of peripheral blood mononuclear cells (PBMCs) exhibits a unique gene expression signature in several types of cancer. In this study, we aimed to explore the breast cancer patient-specific gene expression profile of PBMCs and discuss immunological insight on host antitumor immune responses. We comprehensively analyzed the gene expression of PBMCs by RNA sequencing in the breast cancer patients as compared to that of healthy volunteers (HVs). Pathway enrichment analysis was performed on MetaCoretm to search the molecular pathways associated with the gene expression profile of PBMCs in cancer patients compared with HVs. We found a significant unique gene expression signature, such as the Toll-like receptor (TLR) 3- and TLR4-induced Toll/interleukin-1 receptor domain-containing adapter molecule 1 (TICAM1)-specific signaling pathway in the breast cancer patients as compared to that of healthy volunteers. Distinctive immunological gene expression profiles also showed the possibility of classifying breast cancer patients into subgroups such as T-cell inhibitory and monocyte-activating groups independent of known phenotypes of breast cancer. These preliminary findings suggest that evaluation of gene expression patterns of PBMCs might be both a less invasive diagnostic procedure and a useful way to reveal immunological insight of breast cancer, including biomarkers for cancer immunotherapy, such as immune checkpoint inhibitor therapy.

Mass cytometry of Hodgkin lymphoma reveals a CD4+ regulatory T-cell–rich and exhausted T-effector microenvironment

AbstractIn classical Hodgkin lymphoma (cHL), the host antitumor immune response is ineffective. Hodgkin Reed-Sternberg (HRS) cells have multifaceted mechanisms to evade the immune system, including 9p24.1/CD274(PD-L1)/PDCD1LG2(PD-L2) genetic alterations, overexpression of PD-1 ligands, and associated T-cell exhaustion and additional structural bases of aberrant antigen presentation. The clinical success of PD-1 blockade in cHL suggests that the tumor microenvironment (TME) contains reversibly exhausted T effector cells (Teffs). However, durable responses are observed in patients with β2-microglobulin/major histocompatibility complex (MHC) class I loss on HRS cells, raising the possibility of non-CD8+ T cell–mediated mechanisms of efficacy of PD-1 blockade. These observations highlight the need for a detailed analysis of the cHL TME. Using a customized time-of-flight mass cytometry panel, we simultaneously assessed cell suspensions from diagnostic cHL biopsies and control reactive lymph node/tonsil (RLNT) samples. Precise phenotyping of immune cell subsets revealed salient differences between cHLs and RLNTs. The TME in cHL is CD4+ T-cell rich, with frequent loss of MHC class I expression on HRS cells. In cHLs, we found concomitant expansion of T helper 1 (Th1)-polarized Teffs and regulatory T cells (Tregs). The cHL Th1 Tregs expressed little or no PD-1, whereas the Th1 Teffs were PD-1+. The differential PD-1 expression and likely functional Th1-polarized CD4+ Tregs and exhausted Teffs may represent complementary mechanisms of immunosuppression in cHL.

Abstract 4728: Iron regulation of innate immune pathogen-associated molecular pattern receptors

Abstract Pathogen-associated molecular pattern (PAMP) receptors are key triggers of the pro-inflammatory immune effector functions of the cells of the innate immune system. Ectopic PAMP activation is a contributing factor to both cancer development and pathology, as well as host anti-tumor immune responses. Iron, an essential mineral in biological systems, has a similar dualistic role in cancer. We have shown that iron acts as a key modulator of intracellular signaling cascades downstream from PAMP activation. Cellular iron enrichment enhances the transcriptional activity of a pathogen-induced transcription factor downstream of PAMPs in an immortalized human macrophage cell line treated with a PAMP receptor-specific agonist ligand. Cell surface expression of the receptor was not affected by the iron enrichment; therefore, any modulation of receptor signaling by iron is likely downstream of the receptor. Furthermore, iron supplementation in vitro increases expression of immunity-related genes regulated by the pathogen-induced transcription factor; by contrast, treatment with iron-chelating reagents reduces expression of these genes. These results suggest that the iron content of the tumor microenvironment may have a regulatory role in pathological immunoregulation. In particular, the iron-retaining phenotype of many tumor cells may serve a novel pathological function, inhibiting PAMP-regulated anti-tumoral effector functions of tumor-infiltrating macrophages cells by iron deprivation. Citation Format: Evan Stater. Iron regulation of innate immune pathogen-associated molecular pattern receptors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4728.

Abstract 5675: Single-cell mass cytometry of classical Hodgkin lymphoma defines an exhausted and immunosuppressive microenvironment

Abstract Background: In classical Hodgkin lymphoma (cHL), the rare malignant Hodgkin Reed-Sternberg (HRS) cells are surrounded by an inflammatory infiltrate. Yet, the host anti-tumor immune response is ineffective. HRS cells have multifaceted mechanisms to evade the immune system including 9p24.1/PD-L1/PD-L2 genetic alterations leading to overexpression of PD-1 ligands and subsequent T cell exhaustion, aberrant antigen presentation and modulation of the tumor microenvironment (TME). The clinical success of PD-1 blockade in cHL suggests the TME contains reversibly exhausted T-effectors (Teff). Paradoxically, durable responses are observed in patients with β2M/MHC class I loss on HRS cells, raising the possibility of non-CD8+ mediated mechanisms of efficacy of PD-1 blockade. For this reason, we sought to characterize HRS cells and the surrounding TME. Methods: Using CyTOF technology, we evaluated 7 primary cHL suspensions and 10 reactive lymphoid tissue (RLT) samples at the single-cell protein level. We designed a custom panel of 39 isotope-conjugated antibodies. A combination of surface and intracellular markers distinguish T cell subsets according to lineage, differentiation, polarization, activation and exhaustion. Additional markers were incorporated to identify B cells, NK cells and macrophages. HRS cells were defined by CD15/CD30/Pax5 positivity. Inclusion of β2M and MHC class I allowed assessment of antigen presentation on HRS cells. The data was acquired on a Helios CyTOF and analyzed using a fast k-weighted nearest neighbor algorithm, X-shift. X-shift clustered cells with phenotypic similarities together. Then, samples were separated into cHL and RLT and the contribution of a sample to a given cluster was quantified. Results: Comparison of viable cell suspensions from RLT and cHL revealed loss of naïve T-cells and skewing towards differentiation of Teff in both CD4+ and CD8+ subsets in cHLs. This prompted a second X-shift analysis focused on CD3+ cells, which highlighted salient differences between cHL and RLT within the CD4+ subset. In cHL, we found expansion of Teff and regulatory T cells (Treg) with a reduction of follicular helper T cells. Furthermore, both Treg and Teff populations were largely Th1 (T-bet+/CCR5+) polarized. Evaluation of PD-1 expression showed Tregs had little/no PD-1 while Teff had intermediate/high expression. Hence, Tregs retain functionality in contrast to Teff, which are exhausted, providing two mechanisms of immunosuppression. Manual gating identified HRS cells with a characteristic phenotype: CD15, CD30, Pax5, rosetted by CD4+ T cells. Importantly, we found loss or decrease of β2M and MHC class I in 5/7 cases. Conclusions: The TME in cHL is CD4+ T cell rich with frequent loss of MHC class I on HRS cells. Differential PD-1 expression results in functional CD4+ Tregs and exhausted Teff, a synergistic bases for the observed immunosuppression in cHL. Citation Format: Fathima Z. Cader, Ron C. Schackmann, Xihao Hu, Kirsty Wienand, Robert A. Redd, Bjoern Chapuy, Jing Ouyang, Nicole E. Paul, Evisa Gjini, Mikel Lipschitz, Laura M. Selfors, Philippe Armand, David Wu, Jonathan R. Fromm, Donna Neuberg, Xiaole S. Liu, Scott J. Rodig, Margaret A. Shipp. Single-cell mass cytometry of classical Hodgkin lymphoma defines an exhausted and immunosuppressive microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5675.

Abstract 4706: Extracellular polysaccharides extracted from Parachlorella kessleri enhance host antitumor immune responses and inhibit colon carcinoma growth in mice

Abstract Natural products obtained from various resources are often found to be new sources of effective drugs for disease including cancer. The novel extracellular polysaccharides (exopolysaccharides) purified from Parachlorella kessleri (PCEPS), a generous gift by Panac ADVANCE Co. Ltd. (Tokyo, Japan), were evaluated on their antitumor and immunomodulatory effects in cell culture and mouse colon carcinoma peritoneal dissemination model. In two-dimensional cell culture, the PCEPS treatment inhibited cell growth of both murine and human colon carcinoma cells in a dose- and time-dependent manner. In contrast, the cell proliferation of mouse splenocytes (SPLs) and bone marrow cells (BMCs) were stimulated by the treatment with PCEPS. The treatment with PCEPS also increased specific subpopulations of the cells in BMCs: antigen presenting cells (CD19+ B cells, 33D1+ dendritic cells and CD68+ macrophage) and CD8+ cytotoxic T cells. In three-dimensional spheroid culture, spheroid growth of CT26 cells co-cultured with HL-60 human neutrophilic promyeloblasts and Jurkat cells (human T lymphoblasts), but not THP-1 human monocytes/macrophages, was significantly attenuated by PCEPS treatment. In transwell co-culture of CT26 and HL-60, THP-1 or Jurkat cells, mRNA level of NOX2 in HL-60 and THP-1 cells, and TNFα, IFNγ, IL-2 and granzyme B (GZMB) in Jurkat cells was significantly increased by PCEPS treatment. In a mouse CT26 colon carcinoma peritoneal dissemination model, intraperitoneal injection of PCEPS (10 mg/kg, started from 1 week after CT26 inoculation for 11 days, twice per week) significantly attenuated the growth of CT26 colon carcinoma in syngeneic mice by PCEPS treatment-associated apoptosis without any noticeable adverse effect. Analysis of subpopulation of intraperitoneally infiltrating immune cells collected from CT26 cell tumor-bearing mice found that PCEPS treatment increased CD4+ and CD8+ T lymphocytes, CD19+ B cell, and CD68+ macrophage populations. In contrast, 33D1+ dendritic cell and LY6G+ neutrophil populations were decreased as compared to PBS-treated group. The present study suggests that PCEPS inhibits colon carcinoma growth via direct cell growth inhibition and a stimulation of the host antitumor immune responses. Taken together, the current study suggests that exopolysaccharides derived from Parachlorella kessleri contain significant bioactive materials that inhibit colon carcinoma growth. This study was supported by Kansas State University Johnson Cancer Research Center 2011JCRC-EQ (MT), 2014CRA (ZG and MT), 2015CRA (JH, HH, AN, and MT), 2016CRA (HH and MT), College of Veterinary Medicine Dean's funds 2010CVM-EQ (MT), and NIH grant P20 RR017686 (MT). Citation Format: Susumu Ishiguro, Deepthi Uppalapati, Zachary Goldsmith, Dana Robertson, Jacob Hodge, Hayley Holt, Arashi Nakashima, Katie Turner, Masaaki Tamura. Extracellular polysaccharides extracted from Parachlorella kessleri enhance host antitumor immune responses and inhibit colon carcinoma growth in mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4706.

Abstract 4692: High density of cytotoxic and regulatory T-lymphocytes in gastric cancers with microsatellite instability

Abstract Introduction: MSI-high (MSI-H) colorectal cancer is known to be associated with increased tumor-infiltrating lymphocytes (TILs) and good prognosis. In gastric cancer, however, MSI status has rarely been evaluated in accordance with TILs. The objectives of our study were to clarify the relationships between MSI status and antitumor host immune response and to identify the impact of these factors on the prognosis of gastric cancer. Methods: We evaluated 345 patients with gastric cancer who underwent gastrectomy with MSI typing. The numbers of TILs in tumor center was counted after immunohistochemical staining with anti-CD3, CD4, CD8, Foxp3, and granzyme B to quantify the subset of TILs. To evaluate systemic immune response, differential white blood cell count and prognostic nutritional index (PNI) were obtained. Results: Of the 345 patients, 57 were MSI-H and 288 were non-MSI-H groups. MSI-H tumors carried significantly higher numbers of CD8+ T-cells, Foxp3+ T-cells, GZB+ T cells and higher ratio of Foxp3/CD4 and GZB/CD8. The prognostic effect of TILs was different in MSI-H and non-MSI-H groups. All subsets of TILs were not significant prognostic factor for recurrent-free survival (RFS) and overall survival (OS) in MSI-H group. However, in non-MSI-H group, multivariate analysis showed that stage, PNI and CD4+ T cells was independent prognostic factor for RFS; on the other hand, stage, PNI and ratio of Foxp3/CD4 was independent prognostic factor for OS. Conclusions: The number of subset of TILs and the prognostic influence of systemic and local immune response were different between MSI-H and non-MSI-H tumors. The immunogenicity caused by microsatellite instability and subsequent host immune response is associated with cancer progression and patient prognosis of gastric cancer. Citation Format: Hyoung-Il Kim, Su-Jin Shin, Sang Yong Kim, Yoon Young Choi, Taeil Son, Jae-Ho Cheong, Woo Jin Hyung, Sung Hoon Noh. High density of cytotoxic and regulatory T-lymphocytes in gastric cancers with microsatellite instability [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4692.

Abstract 4719: Small-molecule antagonists of the Aryl Hydrocarbon Receptor (AhR) promote activation of human PBMCs in vitro and demonstrate significant impact on tumor growth and immune modulation in vivo

Abstract Cancer cells utilize a variety of pathways to generate an immune permissive growth environment and evade the host anti-tumor immune response. One such pathway is production of T-cell inhibitory tryptophan (Trp) metabolites, kynurenine and kynurenic acid (KYN), via up-regulation of indoleamine 2,3-dioxygenase (IDO1) and tryptophan 2,3-dioxygenase (TDO2) and up-regulation of the KYN- receptor (aryl hydrocarbon receptor, AhR) in infiltrating lymphoid and myeloid cells. Through AhR activation, KYN both directly and indirectly, via stimulation of regulatory T-cells (Tregs), dendritic cells (DCs) and tumor-associated macrophages (TAM), modulates CD8+ and CD4+ T-cell function resulting in potent inhibition of anti-tumor immunity. Inhibition of AhR activation therefore represents a novel approach to blocking the immuno-inhibitory effects of Trp metabolites generated by endogenous IDO1 and TDO2. To thwart the effects of KYN and other immunosuppressive AhR agonist ligands, we have generated a series of small-molecule antagonists of the human and mouse AhR. To further analyze the effects of AhR inhibition on immuno-modulation and tumor growth, we selected from our series a highly potent antagonist of AhR (IDB-AHRi). In an XRE-dependent luciferase reporter system, IDB-AHRi blocked activation of AhR by 2,3,7,8-Tetrachlorodibenzodioxin (TCDD) with an IC50 of 111 and 3 nM in human HEPG2 and mouse HEPA1C1C7 cell lines respectively. IDB-AHRi inhibited translocation of cytoplasmic AhR to the nucleus and protected AhR from TCDD-induced degradation. When human peripheral blood mononuclear cells were treated with IDB-AHRi ex-vivo, expression of IFN-γ and TNF-α was significantly enhanced, an effect that could be reversed with the addition of TCDD. In vivo, IDB-AHRi dosed at 30 mg/kg (PO QD) in the CT26 colon carcinoma syngeneic mouse model resulted in a reduction of tumor growth, an increase in tumor-infiltrated CD45+CD8+Ki67high T-cells and a significant reduction in the frequency of tumor infiltrated FoxP3+CD4+ regulatory T-cells and tumor associated M2-like macrophages. In summary, this data demonstrates that blocking AhR with a highly potent antagonist can significantly enhance T-cell activity in vitro and drive anti-tumor immunity in vivo, resulting in reduced tumor growth. Citation Format: James Joseph, Marcos Gonzalez-Lopez, Christina Galang, Candy Garcia, Hadia Lemar, Jing Lu, Kedar Vaidya, Marcus Fischer, Christian Frey, Muzaffar Alam, Bing Yao, Michael Dillon, Jeffrey H. Hager, Eleni Venetsanakos, Fred Aswad. Small-molecule antagonists of the Aryl Hydrocarbon Receptor (AhR) promote activation of human PBMCs in vitro and demonstrate significant impact on tumor growth and immune modulation in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4719.

Ovarian cancer and inflammation. Part 1. Pro-inflammatory cytokines.

Ovarian cancer is the most threatening cause of death among gynecologic malignancies and represents the fifth leading cause of death from all cancers for women. Research reveals that ovarian cancer patients exhibit significant immune responses against the tumor. In this review of the current literature chiefly the interaction of ovarian cancer tumor cells and the immune system is discussed. There is increasingly growing evidence that pro-inflammatory cytokines are involved in intricate complex of mechanisms responsible for tumorigenesis, and delicate balance between pro- and anti-inflammatory cytokines is critical for the antitumor host immune response.

Chronic Lymphocytic Leukemia-Derived IL-10 Suppresses Antitumor Immunity.

Chronic lymphocytic leukemia (CLL) patients progressively develop an immunosuppressive state. CLL patients have more plasma IL-10, an anti-inflammatory cytokine, than healthy controls. In vitro human CLL cells produce IL-10 in response to BCR cross-linking. We used the transgenic Eμ-T cell leukemia oncogene-1 (TCL1) mouse CLL model to study the role of IL-10 in CLL associated immunosuppression. Eμ-TCL mice spontaneously develop CLL because of a B cell-specific expression of the oncogene, TCL1. Eμ-TCL1 mouse CLL cells constitutively produce IL-10, which is further enhanced by BCR cross-linking, CLL-derived IL-10 did not directly affect survival of murine or human CLL cells in vitro. We tested the hypothesis that the CLL-derived IL-10 has a critical role in CLL disease in part by suppressing the host immune response to the CLL cells. In IL-10R-/- mice, wherein the host immune cells are unresponsive to IL-10-mediated suppressive effects, there was a significant reduction in CLL cell growth compared with wild type mice. IL-10 reduced the generation of effector CD4 and CD8 T cells. We also found that activation of BCR signaling regulated the production of IL-10 by both murine and human CLL cells. We identified the transcription factor, Sp1, as a novel regulator of IL-10 production by CLL cells and that it is regulated by BCR signaling via the Syk/MAPK pathway. Our results suggest that incorporation of IL-10 blocking agents may enhance current therapeutic regimens for CLL by potentiating host antitumor immune response.

Prognostic role of neutrophil‐to‐lymphocyte ratio on esophageal cancer patients who received definitive chemoradiotherapy

AbstractObjectiveThe neutrophil‐to‐lymphocyte ratio (NLR), a simple biomarker that can reflect the host antitumor immune response, has been associated with patient prognosis in several solid tumors. The aim of the present study was to evaluate the ability of NLR to predict clinical tumor response and prognosis in patients with locally advanced esophageal squamous cell carcinoma who received definitive chemoradiotherapy.MethodsA total of 147 patients with advanced esophageal squamous cell carcinoma treated at Shandong Cancer Hospital Affiliated with Shandong University, Jinan, China, between January 1, 2012 and December 31, 2013 were retrospectively recruited for analysis. The patients were divided into a low NLR group (NLR ≤2.46, n = 74) and a high NLR group (NLR &gt;2.46, n = 73) according to pretreatment NLR. The predictive value of NLR for clinical tumor response and prognosis was examined.ResultsCompared with their matched counterparts, patients in the low NLR group showed a good clinical tumor response (P &lt; 0.001). The NLR before chemoradiotherapy was significantly lower in patients who achieved complete response than in patients who did not achieve complete response (2.2 ± 0.9 vs. 2.7 ± 1.1, P = 0.024). Logistic regression analysis revealed that pretreatment NLR was negatively correlated with tumor response (odds ratio 0.60, 95% confidence interval 0.43–0.84; P = 0.003). In the univariate analysis, cT stage status (PPFS = 0.001; POS = 0.007), tumor response (PPFS &lt; 0.001; POS &lt; 0.001) and NLR (PPFS = 0.005; POS = 0.008) were significantly associated with PFS and OS. The Cox proportional hazards model showed that tumor response (PPFS = 0.002; POS = 0.003) and NLR (PPFS = 0.021; POS = 0.017) were independent predictors of prognosis.ConclusionsIn patients with esophageal squamous cell carcinoma, NLR can be used as a simple marker to predict clinical tumor response and prognosis.

A novel small molecular STAT3 inhibitor, 5Br-6b, induces apoptosis and inhibits migration in colorectal cancer cells.

Signal transducers and activators of transcription 3 (STAT3) represent a transcription factor that is constitutively activated in various cancers. Numerous studies have shown that STAT3 plays crucial roles in cell proliferation and survival, angiogenesis, tumor-promoting inflammation, and suppression of antitumor host immune response in the tumor microenvironment. In this study, we investigated a novel inhibitor, called -6b, to target STAT3 in colorectal cancer cells. The influence of 5Br-6b on the proliferation of colorectal cell lines SW480 and HCT116 was evaluated using an 3-(4, 5-dimethylthiazolyl)-2 and 5-diphenyltetrazolium bromide assay. We detected cell apoptosis after the treatment of 5Br-6b by flow cytometry. In addition, 5Br-6b caused the cleavage of caspase-3 and decreased the expression of Bcl-2. Cancer cell invasion and migration were measured by transwell and wound-healing assay. The potential mechanism was evaluated by western blotting and immunofluorescence. The results show that 5Br-6b inhibits the activation of STAT3, and decreases the expression of its target genes that regulate cell proliferation, migration, and apoptosis. Thus, 5Br-6b is a promising therapeutic drug candidate for colorectal cancer by inhibiting persistent STAT3 signaling.