J Thorac Oncol. 2016 Feb 1. pii: S1556-0864(16)00350-6. doi: 10.1016/j.jtho.2016.01.013. [Epub ahead of print]

Successful Immunotherapy Against a Transplantable Mouse Squamous Lung Carcinoma with Anti-PD-1 and Anti-CD137 Monoclonal Antibodies.

Azpilikueta A1, Agorreta J2, Labiano S1, Pérez-Gracia JL3, Rodríguez A1, Aznar MA1, Ajona D4, Gil-Bazo I3, Larrayoz M5, Teijeira A1, Rodriguez-Ruiz ME6, Pio R4, Montuenga LM2, Melero I7.

Author information

• 1Department of Immunology. Center for Applied Medical Research (CIMA). Universidad de Navarra.
• 2Program in Solid Tumors and Biomarkers. Center for Applied Medical Research (CIMA). Universidad de Navarra; Department of Histology and Pathology. Universidad de Navarra.
• 3Department of Oncology and clinical trial unit. Clínica Universidad de Navarra.
• 4Program in Solid Tumors and Biomarkers. Center for Applied Medical Research (CIMA). Universidad de Navarra; Department of Biochemistry and Genetics. Universidad de Navarra.
• 5Department of Immunology. Center for Applied Medical Research (CIMA). Universidad de Navarra; Department of Histology and Pathology. Universidad de Navarra.
• 6Program in Solid Tumors and Biomarkers. Center for Applied Medical Research (CIMA). Universidad de Navarra.
• 7Department of Immunology. Center for Applied Medical Research (CIMA). Universidad de Navarra; Department of Oncology and clinical trial unit. Clínica Universidad de Navarra. Electronic address: imelero@unav.es.

Abstract

INTRODUCTION:

Anti-PD-1 and anti-PD-L1 antagonist monoclonal antibodies are being developed in the clinic against metastatic non-small cell lungcancer (NSCLC) with special efficacy in patients with squamous cell lung cancer. 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 NTCU mutagenesis in AJ mice. Tumor cells expressed cytokeratins, overexpressed p40 and lacked TTF1, confirming the squamous lineage reported by histology. Over two hundred 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 mAb and monitored for tumor growth/progression or assessed for intratumoral leukocyte infiltration using immunohistochemistry 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 monoclonal antibodies. Single agent therapies lost curative efficacy when treatment started beyond day +17, whereas a combination of anti-PD-1 + 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.

CONCLUSION:

These promising results advocate the use of anti-PD-1/PD-L1 + anti-CD137 mAb combined immunotherapy for the treatment of squamous NSCLC in the clinical setting.