title: Successful Immunotherapy against a Transplantable Mouse Squamous Lung Carcinoma with Anti-PD-1 and Anti-CD137 Monoclonal Antibodies.
abstract: BACKGROUND
  Anti-programmed cell death 1 (anti-PD-1) and anti-programmed cell death ligand 1 (PD-L1) antagonist monoclonal antibodies (mAbs) against metastatic non-small cell lung cancer with special efficacy in patients with squamous cell lung cancer are being developed in the clinic. However, robust and reliable experimental models to test immunotherapeutic combinations in squamous lung tumors are still lacking.
  
  
  METHODS
  We generated a transplantable squamous cell carcinoma cell line (UN-SCC680AJ) from a lung tumor induced by chronic N-nitroso-tris-chloroethylurea mutagenesis in A/J mice. Tumor cells expressed cytokeratins, overexpressed p40, and lacked thyroid transcription factor 1, confirming the squamous lineage reported by histological analysis. More than 200 mutations found in its exome suggested potential for antigenicity. Immunocompetent mice subcutaneously implanted with this syngeneic cell line were treated with anti-CD137 and/or anti-PD-1 mAbs and monitored for tumor growth/progression or assessed for intratumoral leukocyte infiltration using immunohistochemical analysis and flow cytometry.
  
  
  RESULTS
  In syngeneic mice, large 12-day-established tumors derived from the transplantable cell line variant UN-SCC680AJ were amenable to curative treatment with anti-PD-1, anti-PD-L1, or anti-CD137 immunostimulatory mAbs. Single-agent therapies lost curative efficacy when treatment was started beyond day +17, whereas a combination of anti-PD-1 plus anti-CD137 achieved complete rejections. Tumor cells expressed weak baseline PD-L1 on the plasma membrane, but this could be readily induced by interferon-γ. Combined treatment efficacy required CD8 T cells and induced a leukocyte infiltrate in which T lymphocytes co-expressing CD137 and PD-1 were prominent.
  
  
  CONCLUSIONS
  These promising results advocate the use of combined anti-PD-1/PD-L1 plus anti-CD137 mAb immunotherapy for the treatment of squamous non-small cell lung cancer in the clinical setting.
authors: Department of Immunology, Center for Applied Medical Research, Universidad de Navarra.
authors: Arantza
authors: A
authors: Azpilikueta
authors: Program in Solid Tumors and Biomarkers, Center for Applied Medical Research, Universidad de Navarra; Department of Histology and Pathology, Universidad de Navarra.
authors: Jackeline
authors: J
authors: Agorreta
authors: Department of Immunology, Center for Applied Medical Research, Universidad de Navarra.
authors: Sara
authors: S
authors: Labiano
authors: Department of Oncology and Clinical Trial Unit, Clínica Universidad de Navarra.
authors: José Luis
authors: JL
authors: Pérez-Gracia
authors: Department of Immunology, Center for Applied Medical Research, Universidad de Navarra.
authors: Alfonso R
authors: AR
authors: Sánchez-Paulete
authors: Department of Immunology, Center for Applied Medical Research, Universidad de Navarra.
authors: M Angela
authors: MA
authors: Aznar
authors: Program in Solid Tumors and Biomarkers, Center for Applied Medical Research, Universidad de Navarra; Department of Biochemistry and Genetics, Universidad de Navarra.
authors: Daniel
authors: D
authors: Ajona
authors: Department of Oncology and Clinical Trial Unit, Clínica Universidad de Navarra.
authors: Ignacio
authors: I
authors: Gil-Bazo
authors: Department of Immunology, Center for Applied Medical Research, Universidad de Navarra; Department of Histology and Pathology, Universidad de Navarra.
authors: Marta
authors: M
authors: Larrayoz
authors: Department of Immunology, Center for Applied Medical Research, Universidad de Navarra.
authors: Alvaro
authors: A
authors: Teijeira
authors: Program in Solid Tumors and Biomarkers, Center for Applied Medical Research, Universidad de Navarra.
authors: María E
authors: ME
authors: Rodriguez-Ruiz
authors: Program in Solid Tumors and Biomarkers, Center for Applied Medical Research, Universidad de Navarra; Department of Biochemistry and Genetics, Universidad de Navarra.
authors: Ruben
authors: R
authors: Pio
authors: Program in Solid Tumors and Biomarkers, Center for Applied Medical Research, Universidad de Navarra; Department of Histology and Pathology, Universidad de Navarra.
authors: Luis M
authors: LM
authors: Montuenga
authors: Department of Immunology, Center for Applied Medical Research, Universidad de Navarra; Department of Oncology and Clinical Trial Unit, Clínica Universidad de Navarra. Electronic address: imelero@unav.es.
authors: Ignacio
authors: I
authors: Melero
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology*; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000276:immunology; D005260:Female; D007167:Immunotherapy / Q000379:methods*; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000276:immunology; D051379:Mice; D008805:Mice, Inbred A; D008822:Mice, Transgenic; D009368:Neoplasm Transplantation; D061026:Programmed Cell Death 1 Receptor / Q000037:antagonists & inhibitors* / Q000276:immunology; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9 / Q000037:antagonists & inhibitors* / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; C491383:Pdcd1 protein, mouse; D061026:Programmed Cell Death 1 Receptor; D053261:Tumor Necrosis Factor Receptor Superfamily, Member 9
keywords: CD-137; Immunotherapy; Lung cancer; PD-1; PD-L1; Squamous