Abstract 1086: Immune checkpoint inhibitorsCD300AandLAIR1are associated with poor prognosis in clear cell renal cell carcinoma

Immune checkpoint inhibitors targeting the programmed cell death-1 receptor (PD-1) have been shown to improve the survival of patients with clear cell renal cell carcinoma (CCRCC). However, a benefit for CCCRC patients was observed with the FDA-approved PD-1 inhibitor Nivolumab irrespective of PD-1 ligand (PD-L1) expression status indicating there are potentially additional CCRCC checkpoint molecules worth exploring for targeted therapy. We therefore analyzed RNAseq data (n=534, CCRCCs; n=72, normal kidney specimens) from the TCGA project, and found that PD-L1 was not upregulated in CCRCC when compared to normal tissue whereas other checkpoint members i.e. CD300A and LAIR1 were among the most significantly upregulated genes in CCRCCs. In terms of overall survival, high expression of PD-L1 was associated with better outcome in CCRCCs while high expression of CD300A and LAIR1 were significantly associated with worse outcomes. We confirmed these findings in two independent cohorts of CCRCC patients. Furthermore, we performed cell type enrichment analysis, which showed that CD300A and LAIR1 are most likely expressed by tumor-associated macrophages in the CCRCC tumor microenvironment. Our results suggest that PD1/PDL1 might be suboptimal targets in CCRCC and that there are additional unexplored immune checkpoint molecules that warrant our attention. Note: This abstract was not presented at the meeting. Citation Format: Jonas Sjolund, David Lindgren, Helen Nilsson, Martin E. Johansson, Hakan Axelson, Kristian Pietras. Immune checkpoint inhibitors CD300A and LAIR1 are associated with poor prognosis in clear cell renal cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1086.