105P Paired liquid biopsies analysis reveals resistance mechanisms and prognostic factors in patients treated with KRASG12C inhibitors

Results: CD31, CD34, and FLI1 were consistently highly expressed across four of the eight tumour samples, whereas ERG positivity was detected in only one of these four samples.Additionally, one tumour sample exhibited positivity solely for CD34 and FLI1, indicating variability in the expression of endothelial markers across cases.In the RNAseq analyses, 644 differentially expressed genes (DEGs) were identified, with 72 genes upregulated and 572 downregulated in secondary breast angiosarcoma.Gene Ontology (GO) enrichment analysis revealed that these DEGs were predominantly associated with biological processes like metabolism, energy pathways, and protein metabolism. Conclusions:The findings presented highlight the heterogeneity in the expression of endothelial markers and transcriptomic profiles in secondary breast angiosarcoma, contributing to our understanding of this rare and aggressive malignancy.