Geospatial Characterization of Immune Cell Distributions and Dynamics Across the Microenvironment in Clear Cell Renal Cell Carcinoma

Clear cell renal cell carcinoma (ccRCC) is clinically and biologically unique. Only a subset of patients with advanced disease respond to immunotherapy, but those who respond typically have a highly durable progression free period. Predictors of immunotherapy response and resistance that have fared well in other solid organ malignancies have not panned out in ccRCC. For example, high CD8+ T-cell tumor infiltration in ccRCC has paradoxically been associated with poor clinical outcomes.

Recent studies have implicated M2-like tumor associated macrophages (TAMs) with inducing CD8+ T-cells into a terminally exhausted state, partially explaining this paradox. Developing therapies to increase immunotherapy response in ccRCC depends on a more detailed understanding of these biologic processes. We sought to elucidate these TAM-CD8+ interactions within the ccRCC tumor immune microenvironment by adapting a geospatial framework borrowed from the field of ecology to analyze multiplex immunofluorescence samples.

Clustering of CD163+ M2-like TAMs into the stromal compartment at the tumor-stroma interface was associated with worse clinical stage (Tumor/CD163+ nK(75): Stage I/II: 4.4 (IQR -0.5-5.1); Stage III: 1.4 (IQR -0.3-3.5); Stage IV: 0.6 (IQR -2.1-2.1); P = 0.04 between Stage I/II and Stage IV), and worse OS and CSS (Tumor/CD163+ nK(75): median OS – hi = 149mo., lo = 86mo., FDR-adj. Cox p < 0.001; median CSS – hi = 174mo., lo = 85mo.; FDR-adj. Cox p < 0.001). An RNA-seq differential gene expression score was developed using this geospatial metric. It was externally validated in multiple independent cohorts of ccRCC patients including TCGA KIRC, and the IMmotion151, IMmotion150, and JAVELIN Renal 101 clinical trials. Additionally, this CD163+ geospatial pattern was found to be associated with a higher TIM-3+ proportion of CD8+ T-cells, indicative of terminal exhaustion (Tumor-core: 0.07 (IQR 0.04 – 0.14) vs. 0.40 (IQR 0.15 – 0.66), p = 0.05).

These findings demonstrate that geospatial clustering of CD163+ M2-polarized macrophages into the stromal compartment at the tumor-stromal interface was associated with poor clinical outcomes and CD8+ T-cell terminal exhaustion. More broadly, this study shows that specific cellular locations and spatial relationships of the TAM-CD8+ interaction contribute significantly to clinical and biologic outcomes -- highlighting that cellular phenotype and abundance may not adequately describe the ccRCC tumor microenvironment in the absence of geospatial context.

Written by: Nicholas H Chakiryan, MD, Department of Genitourinary Oncology, H Lee Moffitt Cancer Center and Research Institute, Tampa, FL, Translational Oncology, Oregon Health & Science University Knight Cancer Institute, Portland, OR

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