Telomerase-specific oncolytic immunotherapy for promoting efficacy of PD-1 blockade in osteosarcoma

Yusuke Mochizuki, Hiroshi Tazawa, Koji Demiya, Miho Kure, Hiroya Kondo, Tadashi Komatsubara, Kazuhisa Sugiu, Joe Hasei, Aki Yoshida, Toshiyuki Kunisada, Yasuo Urata, Shunsuke Kagawa, Toshifumi Ozaki, Toshiyoshi Fujiwara

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


Immune checkpoint inhibitors including anti-programmed cell death 1 (PD-1) antibody have recently improved clinical outcome in certain cancer patients; however, osteosarcoma (OS) patients are refractory to PD-1 blockade. Oncolytic virotherapy has emerged as novel immunogenic therapy to augment antitumor immune response. We developed a telomerase-specific replication-competent oncolytic adenovirus OBP-502 that induces lytic cell death via binding to integrins. In this study, we assessed the combined effect of PD-1 blockade and OBP-502 in OS cells. The expression of coxsackie and adenovirus receptor (CAR), integrins αvβ3 and αvβ5, and programmed cell death ligand 1 (PD-L1) was analyzed in two murine OS cells (K7M2, NHOS). The cytopathic activity of OBP-502 in both cells was analyzed using the XTT assay. OBP-502-induced immunogenic cell death was assessed by analyzing the level of extracellular ATP and high-mobility group box protein B1 (HMGB1). Subcutaneous tumor models for K7M2 and NHOS cells were used to evaluate the antitumor effect and number of tumor-infiltrating CD8+ cells in combination therapy. K7M2 and NHOS cells showed high expression of integrins αvβ3 and αvβ5, but not CAR. OBP-502 significantly suppressed the viability of both cells, in which PD-L1 expression and the release of ATP and HMGB1 were significantly increased. Intratumoral injection of OBP-502 significantly augmented the efficacy of PD-1 blockade on subcutaneous K2M2 and NHOS tumor models via enhancement of tumor-infiltrating CD8+ T cells. Our results suggest that telomerase-specific oncolytic virotherapy is a promising antitumor strategy to promote the efficacy of PD-1 blockade in OS.

Original languageEnglish
Pages (from-to)1405-1417
Number of pages13
JournalCancer Immunology, Immunotherapy
Issue number5
Publication statusPublished - May 2021


  • ATP
  • CD8
  • Immunogenic cell death
  • Oncolytic adenovirus
  • hTERT

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology
  • Oncology
  • Cancer Research


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