Oncolytic virus-mediated reducing of myeloid-derived suppressor cells enhances the efficacy of PD-L1 blockade in gemcitabine-resistant pancreatic cancer

Yoshinori Kajiwara, Hiroshi Tazawa, Motohiko Yamada, Nobuhiko Kanaya, Takuro Fushimi, Satoru Kikuchi, Shinji Kuroda, Toshiaki Ohara, Kazuhiro Noma, Ryuichi Yoshida, Yuzo Umeda, Yasuo Urata, Shunsuke Kagawa, Toshiyoshi Fujiwara

Research output: Contribution to journalArticlepeer-review


Pancreatic ductal adenocarcinoma (PDAC) is often refractory to treatment with gemcitabine (GEM) and immune checkpoint inhibitors including anti-programmed cell death ligand 1 (PD-L1) antibody. However, the precise relationship between GEM-resistant PDAC and development of an immunosuppressive tumor microenvironment (TME) remains unclear. In this study, we investigated the immunosuppressive TME in parental and GEM-resistant PDAC tumors and assessed the therapeutic potential of combination therapy with the telomerase-specific replication-competent oncolytic adenovirus OBP-702, which induces tumor suppressor p53 protein and PD-L1 blockade against GEM-resistant PDAC tumors. Mouse PDAC cells (PAN02) and human PDAC cells (MIA PaCa-2, BxPC-3) were used to establish GEM-resistant PDAC lines. PD-L1 expression and the immunosuppressive TME were analyzed using parental and GEM-resistant PDAC cells. A cytokine array was used to investigate the underlying mechanism of immunosuppressive TME induction by GEM-resistant PAN02 cells. The GEM-resistant PAN02 tumor model was used to evaluate the antitumor effect of combination therapy with OBP-702 and PD-L1 blockade. GEM-resistant PDAC cells exhibited higher PD-L1 expression and produced higher granulocyte–macrophage colony-stimulating factor (GM-CSF) levels compared with parental cells, inducing an immunosuppressive TME and the accumulation of myeloid-derived suppressor cells (MDSCs). OBP-702 significantly inhibited GEM-resistant PAN02 tumor growth by suppressing GM-CSF-mediated MDSC accumulation. Moreover, combination treatment with OBP-702 significantly enhanced the antitumor efficacy of PD-L1 blockade against GEM-resistant PAN02 tumors. The present results suggest that combination therapy involving OBP-702 and PD-L1 blockade is a promising antitumor strategy for treating GEM-resistant PDAC with GM-CSF-induced immunosuppressive TME formation.

Original languageEnglish
JournalCancer Immunology, Immunotherapy
Publication statusAccepted/In press - 2022


  • Chemoresistance
  • GM-CSF
  • MDSC
  • Oncolytic virus
  • Pancreatic cancer

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Oncology
  • Cancer Research


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