title: T-Cell Immunoglobulin and ITIM Domain (TIGIT) Associates with CD8+ T-Cell Exhaustion and Poor Clinical Outcome in AML Patients.
abstract: T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domain (TIGIT) is a recently identified T-cell coinhibitory receptor. In this study, we aimed to determine the clinical impact of TIGIT in patients with acute myelogenous leukemia (AML) and dissect the role of TIGIT in the pathogenesis of leukemia progression.
  
  
  
  TIGIT expression on T cells from peripheral blood collected from patients with AML was examined by flow cytometry. The correlation of TIGIT expression to clinical outcomes, including rate of complete remission and relapse post-allogeneic stem cell transplantation (alloSCT) in AML patients, was analyzed. Phenotypic and functional study (cytokine release, proliferation, killing, and apoptosis) of TIGIT-expressing T cells were performed. Using siRNA to silence TIGIT, we further elucidated the regulatory role of TIGIT in the T-cell immune response by dissecting the effect of TIGIT knockdown on cytokine release and apoptosis of T cells from AML patients.
  
  
  
  TIGIT expression on CD8(+) T cells is elevated in AML patients and high-TIGIT correlates with primary refractory disease and leukemia relapse post-alloSCT. TIGIT(+) CD8(+) T cells display phenotypic features of exhaustion and exhibit functional impairment manifested by low production of cytokines and high susceptibility to apoptosis. Importantly, their functional defects are reversed by TIGIT knockdown.
  
  
  
  TIGIT contributes to functional T-cell impairment and associates with poor clinical outcome in AML. Our study suggests that blockade of TIGIT to restore T-cell function and antitumor immunity may represent a novel effective leukemia therapeutic. Clin Cancer Res; 22(12); 3057-66. ©2016 AACR.
authors.affiliation: Penn State Hershey Cancer Institute, Penn State University College of Medicine, Hershey, Pennsylvania. Institute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing Key Laboratory of Emerging Infectious Diseases, Beijing, China.
authors.forename: Yaxian
authors.initials: Y
authors.lastname: Kong
authors.affiliation: Penn State Hershey Cancer Institute, Penn State University College of Medicine, Hershey, Pennsylvania. Institute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing Key Laboratory of Emerging Infectious Diseases, Beijing, China.
authors.forename: Liuluan
authors.initials: L
authors.lastname: Zhu
authors.affiliation: Penn State Hershey Cancer Institute, Penn State University College of Medicine, Hershey, Pennsylvania. Department of Microbiology and Immunology, Penn State University College of Medicine, Hershey, Pennsylvania.
authors.forename: Todd D
authors.initials: TD
authors.lastname: Schell
authors.affiliation: Penn State Hershey Cancer Institute, Penn State University College of Medicine, Hershey, Pennsylvania.
authors.forename: Jianhong
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Penn State Hershey Cancer Institute, Penn State University College of Medicine, Hershey, Pennsylvania.
authors.forename: David F
authors.initials: DF
authors.lastname: Claxton
authors.affiliation: Penn State Hershey Cancer Institute, Penn State University College of Medicine, Hershey, Pennsylvania.
authors.forename: W Christopher
authors.initials: WC
authors.lastname: Ehmann
authors.affiliation: Penn State Hershey Cancer Institute, Penn State University College of Medicine, Hershey, Pennsylvania.
authors.forename: Witold B
authors.initials: WB
authors.lastname: Rybka
authors.affiliation: Department of Pathology, Penn State Hershey Medical Center, Penn State University College of Medicine, Hershey, Pennsylvania.
authors.forename: Melissa R
authors.initials: MR
authors.lastname: George
authors.affiliation: Institute of Infectious Diseases, Beijing Ditan Hospital, Capital Medical University, Beijing Key Laboratory of Emerging Infectious Diseases, Beijing, China. hzheng@hmc.psu.edu zenghui@ccmu.edu.cn.
authors.forename: Hui
authors.initials: H
authors.lastname: Zeng
authors.affiliation: Penn State Hershey Cancer Institute, Penn State University College of Medicine, Hershey, Pennsylvania. hzheng@hmc.psu.edu zenghui@ccmu.edu.cn.
authors.forename: Hong
authors.initials: H
authors.lastname: Zheng
mesh_terms: D000328:Adult; D000368:Aged; D000945:Antigens, Differentiation, T-Lymphocyte / Q000378:metabolism; D017209:Apoptosis / Q000235:genetics; D016207:Cytokines / Q000378:metabolism; D005260:Female; D006801:Humans; D015470:Leukemia, Myeloid, Acute / Q000235:genetics / Q000276:immunology* / Q000628:therapy; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology; D008297:Male; D008875:Middle Aged; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D011971:Receptors, Immunologic / Q000235:genetics* / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology* / Q000502:physiology; D017211:Treatment Failure; D055815:Young Adult; D000098862:T Lineage-Specific Activation Antigen 1
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D000098862:T Lineage-Specific Activation Antigen 1; D016207:Cytokines; D034741:RNA, Small Interfering; D011971:Receptors, Immunologic; C534712:TIGIT protein, human