Trastuzumab upregulates programmed death ligand-1 expression through interaction with NK cells in gastric cancer

Kohei Yamashita, Masaaki Iwatsuki, Noriko Yasuda-Yoshihara, Takeshi Morinaga, Yosuke Nakao, Kazuto Harada, Kojiro Eto, Junji Kurashige, Yukiharu Hiyoshi, Takatsugu Ishimoto, Yohei Nagai, Shiro Iwagami, Yoshifumi Baba, Yuji Miyamoto, Naoya Yoshida, Jaffer A. Ajani, Hideo Baba

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Background: The predictive significance of programmed death ligand 1 (PD-L1) for programmed death 1 (PD-1) inhibitors remains unclear in gastric cancer (GC) due to the dynamic alteration by treatments. We aimed to elucidate the effects of trastuzumab (Tmab) on PD-L1 expression in GC. Methods: PD-L1 expression was evaluated by multicolour flow cytometry analysis after co-culturing GG cell lines and immune cells with Tmab. IFN-γ in the co-culture experiments was quantified. Immunohistochemistry (IHC) for PD-L1 expression using clinical samples was also performed to confirm PD-L1 alteration by Tmab. Results: PD-L1 expression was significantly upregulated by Tmab in HER2-amplified GC cell lines co-cultured with peripheral blood mononuclear cells (PBMCs). PD-L1 upregulation by Tmab was also observed in the GC cells co-cultured with NK cells in time-dependent manner, but not with monocytes. IFN-γ concentration in conditioned media from co-cultured PBMCs and NK cells with Tmab was significantly higher and anti-IFN-γ significantly suppress the Tmab-induced PD-L1 upregulation. IHC also suggested PD-L1 upregulation after Tmab treatment. Conclusions: Tmab can upregulate PD-L1 expression on GC cells through interaction with NK cells. These results suggest clinical implications in the assessment of the predictive significance of PD-L1 expression for PD-1 inhibitors.

Original languageEnglish (US)
Pages (from-to)595-603
Number of pages9
JournalBritish journal of cancer
Volume124
Issue number3
DOIs
StatePublished - Feb 2 2021

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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