Abstract 4047: Tumor-infiltrating lymphocytes in renal cancer patients demonstrate a diverse PD-1 expression and characteristic Treg classification
Authors: Sugiyama Daisuke , Muramatsu Tomoaki , Kobayashi Yoichi , Sassa Naoto , Maruyama Shoichi , Goto Momokazu , Akatsuka Yoshiki , Nishikawa Hiroyoshi 
Published: August 2019

Abstract
Immunotherapy has been shown to be effective for a proportion of chemoradiotherapy-refractory cancer patients. In particular, immune checkpoint inhibitors such as anti-CTLA-4 and anti-PD-1 antibodies are more effective for patients with high tumor mutation burden (TMB) or high expression of immune checkpoint molecules. In this study, we investigated immune responses in patients with renal cancer (RCC). Previous studies have demonstrated that the clinical effect of immune checkpoint inhibitors was 20% to 30%, and TMB was moderate (high; melanoma and lung cancer, low: astrocytoma and acute lymphocytic leukemia). We performed immune profiling of lymphocytes in the tumor tissue, normal tissue, and peripheral blood from 13 RCC patients by flow cytometry. Firstly, we examined the difference of CD4+ T cells, CD8+ T cells, and regulatory T (Treg) cells among 3 individual sampling sites. The frequency of CD8+ T cells in the tumor and normal tissues was higher than that of CD4+ T cells in the peripheral blood. In contrast, the frequency of CD4+ T cells in the peripheral blood was the highest, and that of effector-Treg (eTreg) cells (defined by CD3+CD4+FOXP3highCD45RAlow) in the tumor tissue was the highest. Additionally, we found that the RCC patients were arbitrarily classified into three groups based on the frequency of eTreg cells (i.e. high: &gt; 10%, moderate: &gt; 5%, and low: &gt; 0%). Although this simple eTreg classification has not yet been shown to be associated with patient prognosis, this pattern is distinct from that of other cancer types. Secondly, we examined the expression of immune checkpoint molecules in the CD8+ T cells and eTreg cells. The CD8+ T cells in tumor tissue showed various degrees of PD-1 expression. An extremely high PD-1 expression in CD8+ cells was correlated with a moderate to high frequency of eTreg cells. The tumor-infiltrating CD8+ T cells showed a low expression of other checkpoint/accessory molecules such as LAG-3, CTLA-4, and TIGIT. In contrast, tumor-infiltrating eTreg cells showed high TIGIT and CTLA-4 expression, moderate PD-1 expression, and no LAG-3 expression. With regards to other immune-related molecules, the eTreg cells showed high CCR4 and low ICOS expression. These preliminary data implicate that the clinical benefit of immune checkpoint inhibitors for RCC patients could be associated with the high level of PD-1 expression in CD8+ T cells and the magnitude of eTreg cell infiltration into their tumor tissues. By analyzing the mechanism of high PD-1 expression in the CD8+ T cells and assessing the eTreg classification in RCC patients, we speculate that it is possible to develop a new treatment strategy by combining the anti-PD-1 antibody and Treg-depletion therapies. These data, along with additional measurements of samples from further patients, will be presented at the meeting.
Citation Format: Daisuke Sugiyama, Tomoaki Muramatsu, Yoichi Kobayashi, Naoto Sassa, Shoichi Maruyama, Momokazu Goto, Yoshiki Akatsuka, Hiroyoshi Nishikawa. Tumor-infiltrating lymphocytes in renal cancer patients demonstrate a diverse PD-1 expression and characteristic Treg classification [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4047.