Tumor-infiltrating neutrophils predict therapeutic benefit of tyrosine kinase inhibitors in metastatic renal cell carcinoma

Abstract

Tumor-infiltrating neutrophils (TINs) show diverse predictive effects in the context of different cancer types and therapeutic regimens. In this study we investigated their relevance with therapeutic effect of tyrosine kinase inhibitors (TKIs) in metastatic renal cell carcinoma (mRCC). Two independent datasets including 271 mRCC patients treated by TKIs or IL-2/IFN-α based immunotherapy were retrospective included, and TINs were detected by immunohistochemistry. The presence of TINs was observed in 50 (45.0%) samples of the TKI cohort and in 73 (45.6%) samples of the immunotherapy cohort. TINs were associated with shorter overall survival (HR, 1.776; 95%CI, 1.191-2.650; p = 0.004) in the TKI cohort, but not in the immunotherapy cohort (HR, 1.074; 95%CI, 0.767-1.505; p = 0.672). Multivariate Cox analysis confirmed the independent prognostic value of TINs for TKI-treated patients (HR, 2.078, 95%CI, 1.352-3.195; p = 0.001), apart from other parameters. Moreover, survival benefit of TKI therapy was superior to IL-2/IFN-α immunotherapy only among TINs-absent patients (HR, 1.561; 95%CI, 0.927-2.629; p = 0.094). Data mining in the TCGA cohort of renal cell carcinoma revealed the predominant immunosuppressive function of TINs in renal cell carcinoma. The negative correlation between TINs and intratumoral CD8⁺ T cells was further confirmed in the TKI cohort (p = 0.019), the immunotherapy cohort (p = 0.001) and the TCGA cohort (p < 0.001). In conclusion, the presence of TINs was an independent, unfavorable prognostic factor in TKI-treated mRCC patients. TINs could also predict therapeutic benefit of TKIs over IL-2/IFN-α immunotherapy. These findings should be further confirmed within datasets of clinical trials or prospective observational studies.

Keywords: Metastatic renal cell carcinoma; immunosuppressive tumor microenvironment; survival; tumor-infiltrating neutrophils; tyrosine kinase inhibitor.

Figure 1.

Evaluation of tumor-infiltrating neutrophils (TINs) by immunohistochemistry in metastatic renal cell carcinoma. (A-D) Representative microphotographs of TINs-present (A-C) and TINs-absent (D) samples. Scale bars, 50 μm.

Figure 2.

TINs associated with patients’ survival in TKI-treated mRCC. (A and B) Kaplan-Meier analysis of overall survival in the TKI cohort (A) and the immunotherapy cohort (B). p values, log-rank test. (C) Response rate to TKI therapy in mRCC patients grouped by the presence of TINs. p value, Cochran-Mantel-Haenszel test. (D) Kaplan-Meier analysis of progression-free survival in the TKI cohort. p values, log-rank test.

Figure 3.

Predictive value of TINs for TKI benefit. (A-C) Kaplan-Meier curves of overall survival according to therapeutic regimens in all patients (A), TINs-absent patients (B) and TINs-present patients (C). p values, log-rank test. (D) Hazard ratios for overall survival according to therapeutic regimens in patient subgroups. HR, 95% CI and interaction p value, Cox regression model.

Figure 4.

TINs associated with an immunosuppressive microenvironment of renal cell carcinoma. (A) Volcano plot comparing gene expression of TINs-high relative to TINs-low RCC. Differentially expressed genes are labeled in green. (B) Enriched Gene Ontology pathways of down-regulated genes in TINs-high RCC compared to TINs-low RCC. (C) CD8⁺ T cell proportion in TINs-high and TINs-low tumors of TCGA KIPAN cohort. Bars indicate mean value and standard error. p value, Mann–Whitney U test. (D) Representative microphotographs of CD8⁺ T cell high infiltration density and low infiltration density samples. Scale bars, 50μm. (E and F) CD8⁺ T cell density in TINs-absent and TINs-present tumors of the TKI cohort (E) and the immunotherapy cohort (F). p values, Mann–Whitney U test. (G) Expression level CD8⁺ T cell functional genes in TINs-high and TINs-low tumors of TCGA KIPAN cohort. * indicates p<0.05; ** indicates p<0.01; p values calculated by Mann–Whitney U test.