title: A Listeria vaccine and depletion of T-regulatory cells activate immunity against early stage pancreatic intraepithelial neoplasms and prolong survival of mice.
abstract: OBJECTIVE
  Premalignant lesions and early stage tumors contain immunosuppressive microenvironments that create barriers for cancer vaccines. Kras(G12D/+);Trp53(R172H/+);Pdx-1-Cre (KPC) mice, which express an activated form of Kras in pancreatic tissues, develop pancreatic intraepithelial neoplasms (PanIN) that progress to pancreatic ductal adenocarcinoma (PDA). We used these mice to study immune suppression in PDA.
  
  
  METHODS
  We immunized KPC and Kras(G12D/+);Pdx-1-Cre mice with attenuated intracellular Listeria monocytogenes (which induces CD4(+) and CD8(+) T-cell immunity) engineered to express Kras(G12D) (LM-Kras). The vaccine was given alone or in sequence with an anti-CD25 antibody (PC61) and cyclophosphamide to deplete T-regulatory (Treg) cells. Survival times were measured; pancreatic and spleen tissues were collected and analyzed by histologic, flow cytometry, and immunohistochemical analyses.
  
  
  RESULTS
  Interferon γ-mediated, CD8(+) T-cell responses were observed in KPC and Kras(G12D/+);Pdx-1-Cre mice given LM-Kras, but not in unvaccinated mice. Administration of LM-Kras to KPC mice 4-6 weeks old (with early stage PanINs), depleted of Treg cells, significantly prolonged survival and reduced PanIN progression (median survival, 265 days), compared with unvaccinated mice (median survival, 150 days; P = .002), mice given only LM-Kras (median survival, 150 days; P = .050), and unvaccinated mice depleted of Treg cells (median survival, 170 days; P = .048). In 8- to 12-week-old mice (with late-stage PanINs), LM-Kras, alone or in combination with Treg cell depletion, did not increase survival time or slow PanIN progression. The combination of LM-Kras and Treg cell depletion reduced numbers of Foxp3(+)CD4(+) T cells in pancreatic lymph nodes, increased numbers of CD4(+) T cells that secrete interleukin 17 and interferon γ, and caused CD11b(+)Gr1(+) cells in the pancreas to acquire an immunostimulatory phenotype.
  
  
  CONCLUSIONS
  Immunization of KPC mice with Listeria monocytogenes engineered to express Kras(G12D), along with depletion of Treg cells, reduces progression of early stage, but not late-stage, PanINs. This approach increases infiltration of the lesion with inflammatory cells. It might be possible to design immunotherapies against premalignant pancreatic lesions to slow or prevent progression to PDA.
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, the Skip Viragh Center for Clinical Pancreatic Cancer Research, and the Sol Goldman Pancreatic Cancer Center at Johns Hopkins, Baltimore, Maryland; Graduate Program in Immunology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Bridget P
authors.initials: BP
authors.lastname: Keenan
authors.affiliation: Division of Hematology and Oncology, Tisch Cancer Institute and Department of Dermatology, Mount Sinai School of Medicine, New York, New York.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Saenger
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, the Skip Viragh Center for Clinical Pancreatic Cancer Research, and the Sol Goldman Pancreatic Cancer Center at Johns Hopkins, Baltimore, Maryland.
authors.forename: Michel I
authors.initials: MI
authors.lastname: Kafrouni
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, the Skip Viragh Center for Clinical Pancreatic Cancer Research, and the Sol Goldman Pancreatic Cancer Center at Johns Hopkins, Baltimore, Maryland.
authors.forename: Ashley
authors.initials: A
authors.lastname: Leubner
authors.affiliation: Aduro BioTech, Inc, Berkeley, California.
authors.forename: Peter
authors.initials: P
authors.lastname: Lauer
authors.affiliation: Department of Pathology and Department of Translational Molecular Pathology, University of Texas MD Anderson Cancer Center, Houston, Texas.
authors.forename: Anirban
authors.initials: A
authors.lastname: Maitra
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, the Skip Viragh Center for Clinical Pancreatic Cancer Research, and the Sol Goldman Pancreatic Cancer Center at Johns Hopkins, Baltimore, Maryland.
authors.forename: Agnieszka A
authors.initials: AA
authors.lastname: Rucki
authors.affiliation: Department of Cell and Developmental Biology, Knight Cancer Institute, Oregon Health and Sciences University, Portland, Oregon.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Gunderson
authors.affiliation: Department of Cell and Developmental Biology, Knight Cancer Institute, Oregon Health and Sciences University, Portland, Oregon.
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Coussens
authors.affiliation: Aduro BioTech, Inc, Berkeley, California.
authors.forename: Dirk G
authors.initials: DG
authors.lastname: Brockstedt
authors.affiliation: Aduro BioTech, Inc, Berkeley, California.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Dubensky
authors.affiliation: Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland.
authors.forename: Raffit
authors.initials: R
authors.lastname: Hassan
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, the Skip Viragh Center for Clinical Pancreatic Cancer Research, and the Sol Goldman Pancreatic Cancer Center at Johns Hopkins, Baltimore, Maryland.
authors.forename: Todd D
authors.initials: TD
authors.lastname: Armstrong
authors.affiliation: The Sidney Kimmel Comprehensive Cancer Center, the Skip Viragh Center for Clinical Pancreatic Cancer Research, and the Sol Goldman Pancreatic Cancer Center at Johns Hopkins, Baltimore, Maryland. Electronic address: ejaffee@jhmi.edu.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Jaffee
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D039481:CD11b Antigen / Q000378:metabolism; D019496:Cancer Vaccines / Q000276:immunology / Q000627:therapeutic use*; D002278:Carcinoma in Situ / Q000188:drug therapy* / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D021441:Carcinoma, Pancreatic Ductal / Q000188:drug therapy* / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D003520:Cyclophosphamide / Q000494:pharmacology; D004195:Disease Models, Animal; D018450:Disease Progression; D051858:Forkhead Transcription Factors / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism; D019426:Integrases / Q000235:genetics / Q000378:metabolism; D007371:Interferon-gamma / Q000378:metabolism; D020381:Interleukin-17 / Q000378:metabolism; D008089:Listeria monocytogenes / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009154:Mutation; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000378:metabolism; D019707:Receptors, Chemokine / Q000378:metabolism; D050378:T-Lymphocytes, Regulatory / Q000276:immunology* / Q000378:metabolism; D013997:Time Factors; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D039481:CD11b Antigen; D019496:Cancer Vaccines; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; C503133:Gr-1 protein, mouse; D018398:Homeodomain Proteins; D018836:Inflammation Mediators; D020381:Interleukin-17; C584092:PC61 monoclonal antibody; D019707:Receptors, Chemokine; D015534:Trans-Activators; D016159:Tumor Suppressor Protein p53; C084010:pancreatic and duodenal homeobox 1 protein; D007371:Interferon-gamma; D003520:Cyclophosphamide; C045073:Cre recombinase; D019426:Integrases; D016283:Proto-Oncogene Proteins p21(ras)
keywords: Immunity; Listeria Vaccine; Pancreatic Cancer; Tumor Microenvironment