Regulatory T (Treg) cells suppress abnormal/excessive immune responses to self‐ and nonself‐antigens to maintain immune homeostasis. In tumor immunity, Treg cells are involved in tumor development and progression by inhibiting antitumor immunity. There are several Treg cell immune suppressive mechanisms: inhibition of costimulatory signals by CD80 and CD86 expressed by dendritic cells through cytotoxic T‐lymphocyte antigen‐4, interleukin (IL)‐2 consumption by high‐affinity IL‐2 receptors with high CD25 (IL‐2 receptor α‐chain) expression, secretion of inhibitory cytokines, metabolic modulation of tryptophan and adenosine, and direct killing of effector T cells. Infiltration of Treg cells into the tumor microenvironment (TME) occurs in multiple murine and human tumors. Regulatory T cells are chemoattracted to the TME by chemokine gradients such as CCR4‐CCL17/22, CCR8‐CCL1, CCR10‐CCL28, and CXCR3‐CCL9/10/11. Regulatory T cells are then activated and inhibit antitumor immune responses. A high infiltration by Treg cells is associated with poor survival in various types of cancer. Therefore, strategies to deplete Treg cells and control of Treg cell functions to increase antitumor immune responses are urgently required in the cancer immunotherapy field. Various molecules that are highly expressed by Treg cells, such as immune checkpoint molecules, chemokine receptors, and metabolites, have been targeted by Abs or small molecules, but additional strategies are needed to fine‐tune and optimize for augmenting antitumor effects restricted in the TME while avoiding systemic autoimmunity. Here, we provide a brief synopsis of these cells in cancer and how they can be controlled to achieve therapeutic outcomes.

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The spontaneous immune responses against XAGE-1b (GAGED2a) were analyzed in non-small cell lung cancer (NSCLC) patients. An antibody response against XAGE-1b (GAGED2a) was observed in 10% (20/200) of NSCLC patients and in 19% (13/69) of stage IIIB/IV lung adenocarcinoma patients. A CD4 T-cell response was detected in 88% (14/16) and a CD8 T-cell response in 67% (6/9) in the XAGE-1b (GAGED2a) antibody-positive patients examined. Frequent antibody responses and CD4 and CD8 T-cell responses in XAGE-1b (GAGED2a) antibody-positive patients indicate the strong immunogenicity of the XAGE-1b (GAGED2a) antigen in NSCLC patients. We established T-cell clones from PBMCs of antibody-positive patients and determined the DRB1*04:05-restricted XAGE-1b (GAGED2a) 18-31 peptide (14-mer) as a CD4 T cell epitope and the A*02:06-restricted XAGE-1b (GAGED2a) 21-29 peptide (9-mer) as a CD8 T cell epitope. As for peptide recognition, CD4 and CD8 T-cell clones responded to naturally processed antigen. The CD4 T-cell clone recognized DCs pulsed with the synthetic protein or a lysate from XAGE-1b-transfected 293T cells. The CD8 T-cell clone showed cytotoxicity against a tumor expressing XAGE-1b (GAGED2a) and the appropriate HLA class I allele. These findings establish XAGE-1b (GAGED2a) as a promising target for a lung cancer vaccine.More than 70 cancer/testis (CT) antigen gene families have been identified by immunological or genetic approaches. 1-3Several CT antigens such as the NY-ESO-1 antigen etc. have been shown to elicit humoral and cellular immune responses in cancer patients. 4,5 Because of their restricted expression in normal tissues and high immunogenicity, CT antigens are considered attractive targets for cancer vaccines. 6-9XAGE-1 was originally identified by the search for PAGE/ GAGE-related genes using an expression sequence tag database 10 and was shown to exhibit CT antigen characteristics. 11,12 Five identical genes XAGE1A to E have now been identified, located in dispersed fashion in different orientations in a region of approximately 350 kilobases on chromosome Xp11.22.13 They belong to X antigen family genes. The associated protein is designated as G antigen family D member 2 (GAGED2), and GAGED2a and d isoforms have been identified. 10,13 Four transcript variants XAGE-1a, b, c and d have been extensively studied and were shown to be expressed in metastatic melanoma, Ewing sarcoma, and various epithelial tumors such as breast, lung and prostate cancers.14-17 In a serologic search for antigens using recombinant expression cloning (SEREX), we identified XAGE-1b as a dominant antigen recognized by serum from a lung adenocarcinoma patient using an autologous tumor cell line established from malignant pleural effusion as a source of the cDNA library.18 From the analysis with transfected 293T cells using a USO 9-13 mAb specific for XAGE-1b (GAGED2a) protein, we showed that the XAGE-1a and b transcripts code for the 81 amino acid XAGE-1b (GAGED2a) protein. 19 The XAGE-1c transcript codes for 9-and 17-a.a. peptides from an ...

The findings suggested the CCR4 on activated/effector Tregs and non-Tregs was functionally involved in the chemokinetic migration and accumulation of those cells to the tumor site. In vitro findings of efficient elimination of Tregs may give the basis for implementation of a clinical trial to investigate Treg depletion by administration of an anti-hCCR4 mAb to solid cancer patients.

Analysis of cytokine and chemokine production by tumor cell lines including five lung cancers, a malignant mesothelioma, and a malignant melanoma recently established in our laboratory showed rather high production of IL-8 in all tumors and IL-6 in one lung cancer, the malignant mesothelioma, and the malignant melanoma. We investigated the migration of PBMCs to these tumor cells using Transwell plates and showed enrichment of Foxp3+ CD4 regulatory T cells (Tregs) in migrated T cells to both IL-6– and IL-8–producing tumors. Marked induction of CXCR1 expression on Foxp3+ CD4 Tregs by IL-6 followed by IL-8–mediated migration appeared to be responsible for enriched migration. Frequent production of IL-8 by the tumors and Treg migration to those tumors through induction of IL-8R expression by IL-6 is one of the mechanisms for tumor escape.

The immune status of tumors varies, and this may affect the overall survival (OS) of patients. We examined tumors from 120 patients with lung adenocarcinomas with a tissue microarray for T-cell infiltration and the expression of PD-L1 and Galectin-9 (both ligands for inhibitory receptors on T cells), and cancer/testis (CT) antigen XAGE1 (GAGED2a; a tumor antigen often found on lung tumors) expression, to determine their relevance to OS. Patients defined as pStage I-IIIA could be grouped, based on the expression profiles of PD-L1, Galectin-9, and XAGE1, into cluster A, who had prolonged survival, and cluster B, who had shorter survival. The difference in survival of the clusters was confirmed separately for pStage I and pStage II-IIIA patients. Cluster A patients who also had CD4 and CD8 T-cell infiltration showed even better survival, as expected. The findings were confirmed by examining an independent validation cohort of 68 pStage I lung adenocarcinoma patients. Our data showed that PD-L1 expression was a positive indicator, whereas Galectin-9 and XAGE1 expression was negative. In vitro analyses suggested that PD-L1 expression was upregulated by IFNγ secreted from activated T cells in the tumor and Galectin-9 expression was counteracting those T cells. Thus, use of these immune markers enables the creation of a discriminant function with which to classify tumors and predict survival. Cancer Immunol Res; 4(12); 1049-60. ©2016 AACR.

Objective To evaluate the clinical utility of the T-SPOT.TB test for patients with indeterminate results on the QFT-2G test. Materials and Methods

Introduction: Programmed cell death-1 (PD-1) inhibitors effectively treat NSCLC and prolong survival. Robust biomarkers for predicting clinical benefits of good response and long survival with anti-PD-1 therapy have yet to be identified; therefore, predictive biomarkers are needed to select patients with benefits.