Programmed death-1 blockade enhances the antitumor effects of peptide vaccine-induced peptide-specific cytotoxic T lymphocytes

Yu Sawada, Toshiaki Yoshikawa, Manami Shimomura, Tatsuaki Iwama, Itaru Endo, Tetsuya Nakatsura

Research output: Contribution to journalArticlepeer-review

68 Citations (Scopus)


Novel treatment modalities are required urgently in patients with hepatocellular carcinoma (HCC). A vaccine that induces cytotoxic T lymphocytes (CTLs) is an ideal strategy for cancer, and glypican-3 (GPC3) is a potential option for HCC. Blocking the programmed death-1 (PD-1)/PD-L1 pathway is a rational strategy to overcome tumor escape and tolerance toward CTLs. In the present study, we investigated whether anti-PD-1 blocking antibodies (αPD-1 Ab) enhanced the number of vaccine-induced peptide-specific CTLs in peripheral blood mononuclear cells (PBMCs) following the administration of GPC3 peptide vaccine to both patients and in a mouse model. The inhibitory receptor PD-1 was highly expressed in ex vivo GPC3-specific CTLs isolated from the PBMCs of vaccinated HCC patients. In vitro, interferon-γ induced PD-L1 expression in liver cancer cell lines. In addition, PD-1 blockade increased the number of GPC3-specific CTLs, which degranulate against liver cancer cell lines. In vivo experiments using tumor-bearing mouse models showed that the combination therapy of peptide vaccine and αPD-1 Ab suppressed tumor growth synergistically. PD-1 blockade increased the number of peptide-specific tumor-infiltrating T cells (TILs) and decreased the expression of inhibitory receptors on TILs. This study demonstrated that PD-1/PD-L1 blockade augmented the antitumor effects of a peptide vaccine by increasing the immune response of vaccine-induced CTLs, and provided a foundation for the clinical development of a combination therapy using a GPC3 peptide vaccine and αPD-1 Ab.

Original languageEnglish
Pages (from-to)28-36
Number of pages9
JournalInternational journal of oncology
Issue number1
Publication statusPublished - 2015 Jan 1
Externally publishedYes


  • Cytotoxic T lymphocyte
  • Glypican-3
  • Hepatocellular carcinoma
  • Peptide vaccine
  • Programmed death-1

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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