Medical Brief: Hemangiosarcoma Part 2

Medical Brief: Hemangiosarcoma Part 2

In part 1 of our Hemangiosarcoma (HSA) series, we provided a general overview of this aggressive cancer and shared the distribution of germline and somatic mutations across splenic and non-splenic HSA. In part 2, we discuss the genomic sequencing results of 190 splenic and 56 non-splenic HSA samples.

Genomic Sequencing Results of 246 FidoCure® HSA cases


Whole exome sequencing (WES) of canine hemangiosarcoma identified TP53 as the most frequently mutated gene with 59.6% to 66% of samples exhibiting this mutation57,59,60. Similarly, analyzing the FidoCure® database, we also identified TP53 as the most commonly mutated gene in HSA for both the splenic and non-splenic forms of the disease (Figures 3, 4 and 5).

PI3K/AKT/mTOR pathway - PIK3CA and mTOR

A high frequency of mutations is also seen in the genes involved in the PI3K/AKT/mTOR pathway, such as PIK3CA and mTOR. This pathway is commonly altered in cancer and has an important role in regulating cellular proliferation, survival, differentiation and metabolism in canine HSA cells.

In the literature, PIK3CA is one of most commonly mutated oncogenes, present in 29.8% to 46% of canine HSA samples57,60,61. In the FidoCure® database, PIK3CA and mTOR genes are also frequently mutated in canine HSA samples (Figures 3 and 4).

The inhibition of PI3K/mTOR pathway with VDC-597, an inhibitor of both genes, reduced proliferation, migration, and promoted apoptosis, as well as increased antiproliferative effects when combined with doxorubicin in canine HSA cell lines62.

MAPK pathway - NRAS

Mutations in genes that regulate the MAPK pathway, such as N-RAS, are seen in less than 30% of canine HSA samples14,60. The FidoCure® database reveals NRAS mutations in 17.33% of canine splenic HSA (Figures 3 and 5). The NRAS gene is an important activator of the MAPK signaling pathway responsible for cell proliferation, survival and differentiation. In addition, activated NRAS is able to stimulate both MAPK and PIK3CA pathways, suggesting that inhibitors specifically targeting both pathways may be useful in canine HSA60,63.

NRAS and TP53 mutations are mutually exclusive

According to genomic data generated by FidoCure®, NRAS and TP53 mutations are mutually exclusive which reflects the existence of different molecular subtypes of splenic HSA. This finding is in agreement with previously published data60.

NOTCH tumor suppressor genes

In the FidoCure® dataset, we observed more somatic mutations in NOTCH tumor suppressor genes in splenic HSA compared to non-splenic HSA. This gene encodes a type I transmembrane protein related to tumor microenvironment communication that allows cellular differentiation, angiogenesis and tumorigenesis64. As in human angiosarcomas, mutations in NOTCH1 gene may be associated with advanced disease and are observed in canine HSA samples from the FidoCure® database, highlighting the potential role of this gene in cancer progression (Figures 3 and 4)65.

Epigenetic regulation -  KMT2C/D, SETD2

Genes involved in epigenetic regulation, such as KMT2C/D and SETD2, are commonly mutated in canine HSA as revealed through the FidoCure® platform (Figures 3 and 4). These genes are involved in histone methylation and stability of p53 and the PIK3CA/mTOR pathways, acting as tumor suppressor genes66–69. Their downregulation interferes in several biological processes related to regulation of cellular development, differentiation and metabolism in solid cancers68–70. Recent studies associate the PARP1/2 inhibition and KMT2C downregulation in vitro, suggesting that the sensitivity of KMT2C knockdown cells to PARP inhibitors is due to excess DNA damage by unrepaired single-strand breaks (SSB)71.


The genomic heterogeneity in canine HSA leads to a highly complex tumor that may have different therapeutic responses and a poor prognosis in most cases. The understanding of genetic profiles for canine HSA in different breeds may facilitate the development of new therapeutic options, such as targeted therapy, that may improve the median survival time and quality of life in affected animals.


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