Gene expression profiling of anaplastic thyroid carcinoma and coexisting differentiated thyroid carcinoma using the NanoString nCounter system

e18049 Background: Anaplastic thyroid carcinoma (ATC) is one of the worst prognostic malignancies with a 1-year survival rate of 5-20%. ATC is thought to be originated from differentiated thyroid carcinoma (DTC) caused by undifferentiated transformation because ATCs frequently have preexisting or coexisting region of differentiated thyroid carcinoma (co-DTC), but the detailed mechanism is unclear. In this study, we analyzed mRNA expression among ATCs, DTCs and co-DTCs, and compared their molecular characteristics. Methods: Twelve patients with ATC and eight patients with DTC, who were diagnosed at Tsukuba University Hospital between 2009 to 2020, were included in this study. Of 12 ATCs, four cases had co-DTCs. Total RNA was extracted from formalin-fixed paraffin-embedded (FFPE) samples of ATCs, DTCs and co-DTCs. We analyzed mRNA expression profiles among three groups using nCounter PanCancer IO 360 Panel (NanoString Technologies) and nCounter Advanced Analysis (version 2.0.134). The p-values were adjusted using Benjamini-Hochberg method and adjusted p-value < 0.05 was considered as significant. Results: The 1-year survival rate of the 12 ATC cases in this study was 37.5%. Heatmap of pathway revealed that most ATCs showed up-regulation of almost all tumor-related pathways included in the panel except for autophagy while three of ATCs didn’t show immune-related pathways up-regulation, and one co-DTC sample showed similar behavior of pathways to ATCs. The top 10 up-regulated gene in co-DTCs compare to DTCs were BATF3, TDO2, PRF1, BIRC5, MKI67, ANLN, FCGR3A/B, PPARGC1B, C2 and PFKFB3, and gene set enrichment analysis revealed that the genes with differential expression were enriched in gene set of cell proliferation. The top 10 genes with differential expression in ATCs compare to co-DTCs were CXCL5, BRCA2, MMP1, CSCL6, CXCL1, DKK1 and CXCL8, for up-regulation and ID4, ARID1A and EPM2AIP1 for down-regulation. In ATCs, gene sets of cell proliferation, cytokine and chemokine signaling, and myeloid compartment were especially up-regulated. Immune cell profiling showed that ATC had abundant inflammatory cells, especially TILs, neutrophils and macrophages, while co-DTC showed intermediate characteristics between ATC and DTC. Of note, three case of ATCs had lower inflammatory cell scores than the other ATCs except for macrophages and neutrophils, and were clustered as “DTC-like”. Conclusions: These data revealed that co-DTCs showed up-regulation of cell proliferation related genes compare to DTCs, and some ATCs had different immune cell profiles. co-DTCs showed an intermediate immune cell profile between ATC and DTC. Biological profiling of ATCs, DTCs and co-DTCs may help to understand the developmental mechanism of ATCs. In this presentation, we will report the detailed results of mRNA expression analysis with discussion of the previous reports.