title: Multifactorial T-cell hypofunction that is reversible can limit the efficacy of chimeric antigen receptor-transduced human T cells in solid tumors.
abstract: OBJECTIVE
  Immunotherapy using vaccines or adoptively transferred tumor-infiltrating lymphocytes (TIL) is limited by T-cell functional inactivation within the solid tumor microenvironment. The purpose of this study was to determine whether a similar tumor-induced inhibition occurred with genetically modified cytotoxic T cells expressing chimeric antigen receptors (CAR) targeting tumor-associated antigens.
  
  
  METHODS
  Human T cells expressing CAR targeting mesothelin or fibroblast activation protein and containing CD3ζ and 4-1BB cytoplasmic domains were intravenously injected into immunodeficient mice bearing large, established human mesothelin-expressing flank tumors. CAR TILs were isolated from tumors at various time points and evaluated for effector functions and status of inhibitory pathways.
  
  
  RESULTS
  CAR T cells were able to traffic into tumors with varying efficiency and proliferate. They were able to slow tumor growth, but did not cause regressions or cures. The CAR TILs underwent rapid loss of functional activity that limited their therapeutic efficacy. This hypofunction was reversible when the T cells were isolated away from the tumor. The cause of the hypofunction seemed to be multifactorial and was associated with upregulation of intrinsic T-cell inhibitory enzymes (diacylglycerol kinase and SHP-1) and the expression of surface inhibitory receptors (PD1, LAG3, TIM3, and 2B4).
  
  
  CONCLUSIONS
  Advanced-generation human CAR T cells are reversibly inactivated within the solid tumor microenvironment of some tumors by multiple mechanisms. The model described here will be an important tool for testing T cell-based strategies or systemic approaches to overcome this tumor-induced inhibition. Our results suggest that PD1 pathway antagonism may augment human CAR T-cell function.
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care, Department of Medicine, edmund.moon@uphs.upenn.edu.
authors.forename: Edmund K
authors.initials: EK
authors.lastname: Moon
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care, Department of Medicine.
authors.forename: Liang-Chuan
authors.initials: LC
authors.lastname: Wang
authors.affiliation: Department of Microbiology and Institute for Immunology.
authors.forename: Douglas V
authors.initials: DV
authors.lastname: Dolfi
authors.affiliation: Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, Perelman School of Medicine; and.
authors.forename: Caleph B
authors.initials: CB
authors.lastname: Wilson
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care, Department of Medicine.
authors.forename: Raghuveer
authors.initials: R
authors.lastname: Ranganathan
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care, Department of Medicine.
authors.forename: Jing
authors.initials: J
authors.lastname: Sun
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care, Department of Medicine.
authors.forename: Veena
authors.initials: V
authors.lastname: Kapoor
authors.affiliation: Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, Perelman School of Medicine; and.
authors.forename: John
authors.initials: J
authors.lastname: Scholler
authors.affiliation: Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Ellen
authors.initials: E
authors.lastname: Puré
authors.affiliation: Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, Perelman School of Medicine; and.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Milone
authors.affiliation: Department of Pathology and Laboratory Medicine, Abramson Family Cancer Research Institute, Perelman School of Medicine; and.
authors.forename: Carl H
authors.initials: CH
authors.lastname: June
authors.affiliation: Department of Microbiology and Institute for Immunology.
authors.forename: James L
authors.initials: JL
authors.lastname: Riley
authors.affiliation: Department of Microbiology and Institute for Immunology.
authors.forename: E John
authors.initials: EJ
authors.lastname: Wherry
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care, Department of Medicine.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Albelda
mesh_terms: D000818:Animals; D041702:BALB 3T3 Cells; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D010450:Endopeptidases; D005260:Female; D058851:GPI-Linked Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D018093:Gelatinases / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D016219:Immunotherapy, Adoptive; D016246:Lymphocytes, Tumor-Infiltrating / Q000276:immunology*; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D000090204:Mesothelin; D008654:Mesothelioma / Q000276:immunology* / Q000378:metabolism / Q000628:therapy; D051379:Mice; D016688:Mice, Inbred NOD; D016513:Mice, SCID; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D012697:Serine Endopeptidases / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology*; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays; D000099167:Fibroblast Activation Protein Alpha
chemical_list: D010450:Endopeptidases; D058851:GPI-Linked Proteins; D018093:Gelatinases; D008565:Membrane Proteins; D000090204:Mesothelin; D011948:Receptors, Antigen, T-Cell; D012697:Serine Endopeptidases; D000099167:Fibroblast Activation Protein Alpha; C000715528:Msln protein, mouse