Abstract PR016: Systemic T cell metabolic and effector function changes following treatment with PD1 and CTLA4 in patients with kidney cancer
Authors: Greenwood Dalton , Lindau Paul , Roe Caroline , Landis Madelyn , Hongo Rachel , Rini Brian , Irish Jonathan , Rathmell W. Kimryn , Rathmell Jeffrey , Beckermann Kathryn 
Published: August 2023

Abstract
Background: We have previously shown that dysfunctional renal cell carcinoma (RCC) tumor infiltrating lymphocytes (TIL) have glycolytic insufficiencies, and effector function can be rescued by bypassing glycolysis and modulating mitochondrial fitness (Beckermann et al., 2020). We have also shown that RCC TIL biology may be captured in a subset of the peripheral blood T cells, providing an opportunity to assess the tumor immune landscape in noninvasive liquid biopsy from peripheral blood samples (Siska et al., 2018). Methods: We evaluated the peripheral blood of twenty patients with RCC undergoing systemic therapy with PD1 and CTLA4, ten of whom had primary progressive disease and ten who had clinical benefit (SD, PR, CR for 6 months or greater), studying samples before and after three weeks on treatment. Single Cell mRNA gene expression and TCR clonal analysis was assessed in a subset of patients as well as ArcherDx V(D)J sequencing on matched tumor tissue. To assess the impact of mitochondrial membrane potential on T cell responses in patients with ccRCC we flow sorted viable, CD3+ PBMCs with high or low mitochondrial potential. The peripheral blood was analyzed for protein changes using a 44-plex labeled CyTOF antibody panel focused on T cells surface markers, as well as effector and metabolic function. Results: From peripheral blood of patients with ccRCC we find that CD3+ T cells are predominantly composed of subgroups with mitochondrial high membrane potential and expand in number after αPD1+αCTLA4 therapy. Peripheral T cells with low mitochondrial membrane potential are enriched for gene expression pathways associated with cytotoxicity. T cells with mitochondrial low potential also tended to have oligoclonal TCR expansion that were frequently shared between tumor and blood compared to that of mitochondrial high potential T cells. Mitochondrial low T cells were enriched for genes associated with cytotoxicity including CTSW, CD8, KLRK1, and KLRD. The tumor T cell repertoire demonstrated the greatest similarity with peripheral T cells that had low mitochondrial membrane potential. Shared T cells between the tumor and periphery are enriched for chemotaxis, antigen binding, and cytotoxicity signaling pathways. At the protein level, patients with response have lower metabolic activity and greater CD4+ effector T cells, consistent with the scRNA-seq data, while patients with progressive disease have more metabolically active profiles. Conclusions: Single cell gene expression and mass cytometry analysis shows that systemic changes occur in patients with kidney cancer undergoing αPD1 and αCTLA4 treatment. Shared TCR from TIL exist in oligoclonally expanded T cells in the peripheral blood. These shared T cells are enriched in subsets with low mitochondrial membrane potential and express markers of effector function and upregulate cytotoxic T cell pathways.
Citation Format: Dalton Greenwood, Paul Lindau, Caroline Roe, Madelyn Landis, Rachel Hongo, Brian Rini, Jonathan Irish, W. Kimryn Rathmell, Jeffrey Rathmell, Kathryn Beckermann. Systemic T cell metabolic and effector function changes following treatment with PD1 and CTLA4 in patients with kidney cancer [abstract]. In: Proceedings of the AACR Special Conference: Advances in Kidney Cancer Research; 2023 Jun 24-27; Austin, Texas. Philadelphia (PA): AACR; Cancer Res 2023;83(16 Suppl):Abstract nr PR016.