Molecular profiling by RNA expression reveals distinct subtypes of canine splenic hemangiosarcoma

Canine splenic hemangiosarcoma (HSA) is a highly aggressive endothelial malignancy and the standard treatment protocol involves splenectomy followed by chemotherapy. To explore a precision oncology approach, we analyzed the expression of 45 cancer-related-genes in formalin-fixed-, paraffin-embedded-splenic HSA specimens from 27 dogs using the Oncomapa™ qPCR panel. Unsupervised principal component analysis and K-means clustering identified three molecular distinct groups, which were further confirmed using Ward’s hierarchical clustering. The clustering results were validated using the within-cluster sum of squares and silhouette scores, supporting an exploratory three-group solution. The first cluster was marked by increased MET , MAP2K1/2 , FLT3 , SRC , AKT2 , TP53 , PDGFRA , SETD2 , and NR3C1 expression, suggesting activation of the MAPK and PI3K/AKT pathways, specific TK receptor activation (MET, FLT3, and PDGFRA), and stress and immune regulation (NR3C1 and TP53). The second cluster exhibited elevated expression levels of BCL2, NOTCH1, RET, and KIT, indicating mechanisms of apoptosis evasion, enhanced cell survival, and potential targets for tyrosine kinase inhibition. The third cluster, characterized by the overexpression of MYC, TOP2A, RRM2, TYMS, and BRCA1, showed a molecular profile associated with elevated proliferative signaling, DNA synthesis, and DNA repair-related mechanisms. Based on these signatures, we propose cluster-specific candidate therapeutic hypotheses for future validation. This study suggests that gene expression profiling may contribute to categorizing canine hemangiosarcoma into clinically relevant subtypes, providing a foundation for future investigations into personalized therapeutic approaches that require further biological validation.