PT - JOURNAL ARTICLE AU - Nagaoka, Koji AU - Shirai, Masataka AU - Taniguchi, Kiyomi AU - Hosoi, Akihiro AU - Sun, Changbo AU - Kobayashi, Yukari AU - Maejima, Kazuhiro AU - Fujita, Masashi AU - Nakagawa, Hidewaki AU - Nomura, Sachiyo AU - Kakimi, Kazuhiro TI - Deep immunophenotyping at the single-cell level identifies a combination of anti-IL-17 and checkpoint blockade as an effective treatment in a preclinical model of data-guided personalized immunotherapy AID - 10.1136/jitc-2020-001358 DP - 2020 Oct 01 TA - Journal for ImmunoTherapy of Cancer PG - e001358 VI - 8 IP - 2 4099 - http://jitc.bmj.com/content/8/2/e001358.short 4100 - http://jitc.bmj.com/content/8/2/e001358.full SO - J Immunother Cancer2020 Oct 01; 8 AB - Background Although immune checkpoint blockade is effective for several malignancies, a substantial number of patients remain refractory to treatment. The future of immunotherapy will be a personalized approach adapted to each patient’s cancer-immune interactions in the tumor microenvironment (TME) to prevent suppression of antitumor immune responses. To demonstrate the feasibility of this kind of approach, we developed combination therapy for a preclinical model guided by deep immunophenotyping of the TME.Methods Gastric cancer cell lines YTN2 and YTN16 were subcutaneously inoculated into C57BL/6 mice. YTN2 spontaneously regresses, while YTN16 grows progressively. Bulk RNA-Seq, single-cell RNA-Seq (scRNA-Seq) and flow cytometry were performed to investigate the immunological differences in the TME of these tumors.Results Bulk RNA-Seq demonstrated that YTN16 tumor cells produced CCL20 and that CD8+ T cell responses were impaired in these tumors relative to YTN2. We have developed a vertical flow array chip (VFAC) for targeted scRNA-Seq to identify unique subtypes of T cells by employing a panel of genes reflecting T cell phenotypes and functions. CD8+ T cell dysfunction (cytotoxicity, proliferation and the recruitment of interleukin-17 (IL-17)-producing cells into YTN16 tumors) was identified by targeted scRNA-Seq. The presence of IL-17-producing T cells in YTN16 tumors was confirmed by flow cytometry, which also revealed neutrophil infiltration. IL-17 blockade suppressed YTN16 tumor growth, while tumors were rejected by the combination of anti-IL-17 and anti-PD-1 (Programmed cell death protein 1) mAb treatment. Reduced neutrophil activation and enhanced expansion of neoantigen-specific CD8+ T cells were observed in tumors of the mice receiving the combination therapy.Conclusions Deep phenotyping of YTN16 tumors identified a sequence of events on the axis CCL20->IL-17-producing cells->IL-17-neutrophil-angiogenesis->suppression of neoantigen-specific CD8+ T cells which was responsible for the lack of tumor rejection. IL-17 blockade together with anti-PD-1 mAb therapy eradicated these YTN16 tumors. Thus, the deep immunological phenotyping can guide immunotherapy for the tailored treatment of each individual patient’s tumor.