Multiomic analysis and immunoprofiling

5 8 3 3 jci.org Volume 130 Number 11 November 2020 Introduction Angiosarcomas represent a rare group of soft-tissue sarcomas (1, 2) and are aggressive endothelial cell tumors of vascular or lymphatic origin. These tumors demonstrate remarkable heterogeneity in terms of clinical presentation and behavior and can develop in various anatomical structures, including cutaneous regions of the head and neck, breast, viscera, and bone. Despite their rarity, several well-defined risk factors have been identified. Angiosarcomas arise in distinct clinical settings, either de novo (primary) or following radiotherapy or chronic lymphedema (secondary) (2). Regardless of etiology or anatomical origin, angiosarcomas are characterized by a challenging clinical course with limited treatment options and a dismal prognosis. Contemporary treatment of localized angiosarcoma involves a multimodality approach incorporating surgical resection with wide margins when feasible, as well as radiotherapy and/or chemotherapy in select clinical scenarios. In the metastatic setting, chemotherapeutic agents including paclitaxel, doxorubicin, or targeted agents are typically administered, albeit with limited efficacy or clinical benefit (2, 3). At the molecular level, specific genetic alterations have been correlated with clinical phenotypes, of which MYC amplification in secondary angiosarcoma of the breast is among the best characterized (4). Mutations involving the angiogenesis-related genes PTPRB and/or PLCG1 (5), as well as FLT4 amplification have been observed (6, 7). Additionally, radiation-induced and post-lymphedema angiosarcomas were shown to be transcriptomically distinct from primary angiosarcomas in 1 study (8). Between UVassociated and radiation-associated cases, unique genome-wide DNA methylation clusters have been recognized (9). More recently, a patient-partnered research initiative (Angiosarcoma Project Angiosarcomas are rare, clinically aggressive tumors with limited treatment options and a dismal prognosis. We analyzed angiosarcomas from 68 patients, integrating information from multiomic sequencing, NanoString immuno-oncology profiling, and multiplex immunohistochemistry and immunofluorescence for tumor-infiltrating immune cells. Through whole-genome sequencing (n = 18), 50% of the cutaneous head and neck angiosarcomas exhibited higher tumor mutation burden (TMB) and UV mutational signatures; others were mutationally quiet and non–UV driven. NanoString profiling revealed 3 distinct patient clusters represented by lack (clusters 1 and 2) or enrichment (cluster 3) of immune-related signaling and immune cells. Neutrophils (CD15+), macrophages (CD68+), cytotoxic T cells (CD8+), Tregs (FOXP3+), and PD-L1+ cells were enriched in cluster 3 relative to clusters 2 and 1. Likewise, tumor inflammation signature (TIS) scores were highest in cluster 3 (7.54 vs. 6.71 vs. 5.75, respectively; P < 0.0001). Head and neck angiosarcomas were predominant in clusters 1 and 3, providing the rationale for checkpoint immunotherapy, especially in the latter subgroup with both high TMB and TIS scores. Cluster 2 was enriched for secondary angiosarcomas and exhibited higher expression of DNMT1, BRD3/4, MYC, HRAS, and PDGFRB, in keeping with the upregulation of epigenetic and oncogenic signaling pathways amenable to targeted therapies. Molecular and immunological dissection of angiosarcomas may provide insights into opportunities for precision medicine. Multiomic analysis and immunoprofiling reveal distinct subtypes of human angiosarcoma