Introduction

Renal cell carcinoma (RCC) is considered an immunogenic tumor, and novel immune checkpoint inhibitors have impressive antitumor responses. However, little is known about comprehensive immunological signature patterns of tumor-infiltrating lymphocytes (TILs) in RCC patients. We investigated the surface marker expressions of TILs and classified them based on their functional populations. Moreover, we explored the presence of intra-tumor diversity of surface marker expressions of TILs in each individual.

Methods

We extracted 109 TILs from 80 patients who underwent surgical resection of RCC, of which 44 TILs were multiply extracted from 15 patients. Each TIL was characterized on the basis of functional T-cell populations using 10 surface marker expressions measured by flow cytometry. Immunological classification was performed by unsupervised clustering analysis of TILs. Comparisons between the surface marker expressions and clinical features were evaluated by logistic regression analysis. Distributions of overall metastasis free survival (MFS) time and recurrence free survival (RFS) was estimated with Kaplan-Meier method and immunological classification was assessed with the log-rank test.

Results

All of the TILs were classified into three groups, which correlated significantly with a substantial number of TILs (p<0.001) and the population of circulating T-cell subsets. Also 35 patients (81.4%) within Group III had lower Fuhrman Grade tumor (G1, 2) whereas 19 patients (47.5%) within Group I, II had higher Fuhrman Grade tumor (G3, 4) (p=0.028). In multivariate analysis, only Fuhrman grade was also significantly correlated with this immunological classification (odds ratio: 0.253, 95% Confidence Interval (CI): 0.094-0.678, p=0.006). Importantly, this classification was significantly correlated with overall MFS (hazard ratio (HR): 0.449, 95% CI: 0.243-0.832, p=0.011) and RFS (HR: 0.475, 95%CI: 0.238-0.948, p=0.035) in multivariate analysis. Also, we discovered the presence of intra-tumoral diversity in the classification of 3 (20%) of the 15 patients.

Conclusions

This study showed the presence of classable diversity in the immunological signature of TILs correlated with tumor aggressiveness and prognosis that is observed even within the individual tumor in some patients with RCC.

Funding

Shionogi Co. Ltd. (Osaka, Japan) (H.W.) _x000D_ Osaka Kidney Bank (Osaka, Japan) (A.K.) _x000D_ The Public Trust Surgery Research Fund (Tokyo, Japan) (A.K.).