Abstract 226: Tumor-infiltrating lymphocyte diversity and clear cell renal cell carcinoma
Authors: Ferrall-Fairbanks Meghan C. , Chakiryan Nicholas , Chobrutskiy Boris I. , Kim Youngchul , Teer Jamie K. , Berglund Anders , Mulé James , Fournier Michelle , Siegel Erin M. , Katende Esther N. , Blanck George , Manley Brandon J. , Altrock Philipp M. 
Published: July 2021

Abstract
The availability of systemic treatments of metastatic clear cell renal cell carcinoma (ccRCC) has evolved steadily over the past decade, particularly with the availability of drugs that work in the microenvironment through immune checkpoint blockade (ICB). However, various studies have indicated that response to ICB is not likely driven only by mutational burden, neoantigen burden, or PD-L1 status. We here employed genomics approaches to recover V(D)J recombination sequences from primary tumor bulk RNA sequencing from two ccRCC cohorts; Moffitt Total Cancer Care Cohort (n=105) and the Clinical Proteomic Tumor Analysis Consortium Cohort (n=110). We applied an ecological generalized diversity index (GDI) to quantify tumor infiltration by CDR3 sequences from patient tumors using three point-estimate descriptions: richness, evenness, and inflection point of the GDI. GDI has multiple properties that render it more flexible than the commonly used Shannon index, e.g. the inflection point q, which can be understood as a dataset specific diversity estimate that specifically balances richness and evenness of the distribution that defines diversity. Individuals with larger and more aggressive tumors had increased richness diversity of tumoral CDR3 sequences, specifically in sequences recovered from T-cell receptor alpha (TRA) and B-cell immunoglobulin lambda light chain. Furthermore, the TRA inflection point q diversity stratified patients based on survival, with individuals that had a larger inflection point q diversity having improved overall survival (hazard ratio of 0.526, p-value 0.036 from multivariate Cox regression). We also found significant discrimination of diversity between racial and gender differences in tumor-infiltrating lymphocyte diversity. Non-white patients showed a 2.1-fold increase in evenness in B-cell receptors compared to white patients; T-cell receptors gamma and delta inflection point q diversity was increased at least 1.7-fold in female patients compared to male patients. These demographic differences highlight the need to further investigate race- and gender-related differences in immune infiltration in ccRCC. With ICB being first line therapy of metastatic ccRCC, it is critical to define and evaluate novel analytical tools to characterize the level of immune cell infiltration and diversity. We have demonstrated here that the ecological generalized diversity index shows promise as a novel quantitative, prognostic biomarker for ccRCC, with the potential to extend to other malignancies.
Citation Format: Meghan C. Ferrall-Fairbanks, Nicholas Chakiryan, Boris I. Chobrutskiy, Youngchul Kim, Jamie K. Teer, Anders Berglund, James Mulé, Michelle Fournier, Erin M. Siegel, Esther N. Katende, George Blanck, Brandon J. Manley, Philipp M. Altrock. Tumor-infiltrating lymphocyte diversity and clear cell renal cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 226.