Multi-region exome sequencing to determine the origin of esophageal spindle-cell squamous cell carcinoma.

Abstract

4072 Background: Esophageal spindle-cell squamous cell carcinoma (ESS) is a rare biphasic neoplasm composed of carcinomatous and sarcomatous components. However, the genomic origin and gene signature of ESS remain unclear. Methods: A total of 24 patients diagnosed with ESS were enrolled from Shanghai Chest Hospital and underwent either radical resection (23/24) or endoscopic submucosal dissection (1/24). Laser-capture microdissection was employed to isolate cancerous and sarcomatous components from tumor and lymph node metastatic tissues. The cancerous components were subsequently microdissected based on morphology. Whole exome sequencing (WES) was conducted on both tumor tissues and paired white cell samples to analyze genomic profiles. Results: The tumor tissue samples of carcinomatous and sarcomatous components showed high mutational commonality. With the same top high-frequency mutant genes, mutation signatures, and tumor mutation burden, paired samples shared a median of 25.5% mutation sites. Focal gains were found on chromosomes 3q29, 5p15.33, and 11q13.3. Altered genes were mainly enriched in the RTK-RAS signaling pathway. Phylogenetic trees showed a monoclonal origin of ESS. The most frequently mutated oncogene in the trunk was TP53, followed by NFE2L2, KMT2D, and MUC16. It showed a significant association of CDC27, LRP2, APC, and SNAPC4 mutations with poor prognosis in ESS patients. Our data highlight the monoclonal origin of ESS with TP53 as a potent driver oncogene, suggesting new targeted therapies and immunotherapies as treatment options. Conclusions: In conclusion, our results regarding to the mutation characteristics of microdissected samples substantiate the monoclonal origin of both the carcinomatous and sarcomatous components of ESS.