Abstract 5357: Mutational and transcriptomic profiling identify distinct angiogenic and inflammatory subtypes of angiosarcoma

Angiosarcoma is an aggressive, albeit rare cancer in humans. The cause of the vast majority of sporadic angiosarcomas is unknown, mortality is high, and no therapeutic targets have been identified to improve outcomes. Hemangiosarcoma (HSA) is a common cancer of dogs, and it shares histopathologic features with human angiosarcoma. In our previous work, canine HSAs were classified into angiogenic, inflammatory, and adipogenic subtypes based on transcriptional profiles. However, the genetic and molecular events that regulate transcriptional subtypes in angiosarcoma are not currently understood. Our goal was to use a comparative genomics approach to apply knowledge from appropriately powered canine studies to inform our research into human sarcomas. In this study, we identified recurrent mutations in RNASeq data from 93 HSAs and 16 nonmalignant controls, based on mutations first identified in exomes from 42 paired tumor and normal samples. In addition to identifying recurrent somatic mutations we also identified translocation fusions, allowing elucidation of oncogenic mechanisms for vascular endothelial growth factor receptors (VEGFR), phosphoinositide-3 kinase (PIK3) signaling pathways, and the p53 DNA damage repair pathway in canine HSA. Significantly, mutational signatures were associated with distinct molecular subtypes of canine hemangiosarcomas, and both the angiogenic and the inflammatory subtypes were apparent in RNASeq data from human angiosarcomas (n=14), suggesting that comparable etiologic mechanisms are operative in the canine and human disease. Our ongoing work seeks to understand how the molecular mechanisms give rise to molecular subtypes of angiosarcoma by defining the association between driver mutations, signaling pathway alterations and transcriptional patterns, which should allow us to identify rational therapeutic targets. Citation Format: Jong Hyuk Kim, Kate Megquier, Aaron L. Sarver, Rachael Thomas, Chao Wang, Ingegerd Elvers, Elinor Karlsson, Matthew Breen, Kerstin Lindblad-Toh, Jaime F. Modiano. Mutational and transcriptomic profiling identify distinct angiogenic and inflammatory subtypes of angiosarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5357.