title: Toca 511 gene transfer and treatment with the prodrug, 5-fluorocytosine, promotes durable antitumor immunity in a mouse glioma model.
abstract: BACKGROUND
  Toca 511 (vocimagene amiretrorepvec) is a retroviral replicating vector encoding an optimized yeast cytosine deaminase (CD). Tumor-selective expression of CD converts the prodrug, 5-fluorocytosine (5-FC), into the active chemotherapeutic, 5-fluorouracil (5-FU). This therapeutic approach is being tested in a randomized phase II/III trial in recurrent glioblastoma and anaplastic astrocytoma (NCT0241416). The aim of this study was to identify the immune cell subsets contributing to antitumor immune responses following treatment with 5-FC in Toca 511-expressing gliomas in a syngeneic mouse model.
  
  
  METHODS
  Flow cytometry was utilized to monitor and characterize the immune cell infiltrate in subcutaneous Tu-2449 gliomas in B6C3F1 mice treated with Toca 511 and 5-FC.
  
  
  RESULTS
  Tumor-bearing animals treated with Toca 511 and 5-FC display alterations in immune cell populations within the tumor that result in antitumor immune protection. Attenuated immune subsets were exclusive to immunosuppressive cells of myeloid origin. Depletion of immunosuppressive cells temporally preceded a second event which included expansion of T cells which were polarized away from Th2 and Th17 in the CD4+ T cell compartment with concomitant expansion of interferon gamma-expressing CD8+ T cells. Immune alterations correlated with clearance of Tu-2449 subcutaneous tumors and T cell-dependent protection from future tumor challenge.
  
  
  CONCLUSIONS
  Treatment with Toca 511 and 5-FC has a concentrated effect at the site of the tumor which causes direct tumor cell death and alterations in immune cell infiltrate, resulting in a tumor microenvironment that is more permissive to establishment of a T cell mediated antitumor immune response.
authors.affiliation: Tocagen Inc., San Diego, California; DNAtrix Inc., Houston, Texas; University of California Los Angeles, Los Angeles, California; Department of Gastroenterological Surgery, Hokkaido University, Sapporo, Japan; Department of Cell Biology and Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, Florida.
authors.forename: Leah A
authors.initials: LA
authors.lastname: Mitchell
authors.affiliation: Tocagen Inc., San Diego, California; DNAtrix Inc., Houston, Texas; University of California Los Angeles, Los Angeles, California; Department of Gastroenterological Surgery, Hokkaido University, Sapporo, Japan; Department of Cell Biology and Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, Florida.
authors.forename: Fernando
authors.initials: F
authors.lastname: Lopez Espinoza
authors.affiliation: Tocagen Inc., San Diego, California; DNAtrix Inc., Houston, Texas; University of California Los Angeles, Los Angeles, California; Department of Gastroenterological Surgery, Hokkaido University, Sapporo, Japan; Department of Cell Biology and Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, Florida.
authors.forename: Daniel
authors.initials: D
authors.lastname: Mendoza
authors.affiliation: Tocagen Inc., San Diego, California; DNAtrix Inc., Houston, Texas; University of California Los Angeles, Los Angeles, California; Department of Gastroenterological Surgery, Hokkaido University, Sapporo, Japan; Department of Cell Biology and Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, Florida.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kato
authors.affiliation: Tocagen Inc., San Diego, California; DNAtrix Inc., Houston, Texas; University of California Los Angeles, Los Angeles, California; Department of Gastroenterological Surgery, Hokkaido University, Sapporo, Japan; Department of Cell Biology and Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, Florida.
authors.forename: Akihito
authors.initials: A
authors.lastname: Inagaki
authors.affiliation: Tocagen Inc., San Diego, California; DNAtrix Inc., Houston, Texas; University of California Los Angeles, Los Angeles, California; Department of Gastroenterological Surgery, Hokkaido University, Sapporo, Japan; Department of Cell Biology and Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, Florida.
authors.forename: Kei
authors.initials: K
authors.lastname: Hiraoka
authors.affiliation: Tocagen Inc., San Diego, California; DNAtrix Inc., Houston, Texas; University of California Los Angeles, Los Angeles, California; Department of Gastroenterological Surgery, Hokkaido University, Sapporo, Japan; Department of Cell Biology and Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, Florida.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Kasahara
authors.affiliation: Tocagen Inc., San Diego, California; DNAtrix Inc., Houston, Texas; University of California Los Angeles, Los Angeles, California; Department of Gastroenterological Surgery, Hokkaido University, Sapporo, Japan; Department of Cell Biology and Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, Florida.
authors.forename: Harry E
authors.initials: HE
authors.lastname: Gruber
authors.affiliation: Tocagen Inc., San Diego, California; DNAtrix Inc., Houston, Texas; University of California Los Angeles, Los Angeles, California; Department of Gastroenterological Surgery, Hokkaido University, Sapporo, Japan; Department of Cell Biology and Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, Florida.
authors.forename: Douglas J
authors.initials: DJ
authors.lastname: Jolly
authors.affiliation: Tocagen Inc., San Diego, California; DNAtrix Inc., Houston, Texas; University of California Los Angeles, Los Angeles, California; Department of Gastroenterological Surgery, Hokkaido University, Sapporo, Japan; Department of Cell Biology and Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, Florida.
authors.forename: Joan M
authors.initials: JM
authors.lastname: Robbins
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000276:immunology*; D045744:Cell Line, Tumor; D043525:Cytosine Deaminase; D004195:Disease Models, Animal; D005437:Flucytosine / Q000627:therapeutic use*; D015316:Genetic Therapy; D005822:Genetic Vectors; D005910:Glioma / Q000188:drug therapy* / Q000276:immunology*; D007109:Immunity; D051379:Mice; D009000:Monocytes / Q000187:drug effects; D022423:Myeloid Cells / Q000187:drug effects; D011355:Prodrugs / Q000627:therapeutic use; D012190:Retroviridae; D013601:T-Lymphocytes / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; D011355:Prodrugs; D005437:Flucytosine; D043525:Cytosine Deaminase
keywords: 5-fluorouracil; cytosine deaminase; immunotherapy; myeloid-derived suppressor cell; retroviral gene transfer