Origins and timing of emerging lesions in advanced renal cell carcinoma

Abstract

Purpose: Renal cell carcinoma (RCC) with venous tumor thrombus (VTT) arising from the primary tumor occurs in 4-10% of cases and is associated with advanced disease. RCC with VTT and distant metastasis represents a unique clinical entity, and provides opportunities to examine the origins and relative timing of tumor lesion emergence and to identify molecular correlates with disease state. Experimental Design: We performed genomic and evolutionary analyses on 16 RCC patients with VTT, with eight also having metastases, using multi-region exome and RNA sequencing. Results: No genomic alterations were specifically associated with the VTT or metastasis lesions; each tumor had multiple hallmark driver alterations, consistent with advanced disease state. We found that 21% (3/14) of clear-cell RCC cases could be assigned a previously defined "evolutionary subtype". Somatic mutation signatures were largely consistent with previously established RCC signatures, and showed low heterogeneity across regions of each tumor. Mismatch repair and homologous recombination ("BRCA-ness") deficiency signatures consistently co-occurred across most tumors, suggesting a pervasive role for intracellular DNA damage in RCC and the potential for related treatment strategies. Phylogenetic timing analysis of metastatic cases suggested that in most tumors, metastases branched from the primary tumor prior to formation of VTT and in some cases before diversification of the primary tumor. Both VTT and the earliest metastases were predicted to emerge many years prior to diagnosis. Transcriptional landscape analysis identified key differences distinguishing each lesion type from primary tumor: VTT upregulated TNF𝛼 signaling and associated inflammatory pathways, whereas metastases upregulated MTOR signaling. Conclusions: Our results provide a map of how RCC tumors can evolve, with metastatic clones typically emerging early in RCC development and taking hold via MTOR signaling, and later formation of VTT via local inflammatory processes.