Abstract 774: Microdissected gene expression profiling of recurrent nasopharyngeal carcinoma

Abstract Nasopharyngeal cancer (NPC) is an EBV-driven epithelial carcinoma with a recurrence rate of 30%. Biological pathways and predictive markers for recurrence remain understudied. Further, NPC tumors are associated with an intense inflammatory infiltrate, masking gene expression signals from the tumor epithelial compartment. We perform laser-capture microdissection on a preliminary cohort of 12 tumors, including primary tumors from recurrent and non-recurrent cases matched for stage of disease. Smart-3SEQ, a novel 3’ end RNA-Seq technique which allows for the accurate quantification of transcript abundance in FFPE samples, was performed to obtain gene expression libraries. Tumor epithelial and microenvironment regions from were separately microdissected, giving a total of 42 histologically-pure gene expression libraries. Raw reads were mapped to the human hg19 and EBV genomes and gene expression counts were obtained with Subread. Differential gene expression and gene set enrichment was performed in R with DESeq2 and fgsea respectively. We observed that primary NPC tumors that did not recur were significantly enriched for immune processes, including leukocyte mediated immunity, innate immune response and lymphocyte activation (padj < 1E-9 for all). The top differentially expressed genes in this group included mediators of inflammation such as STAT1 (padj = 0.0204). Critically, these gene expression changes were observed within the tumor epithelial compartment. In contrast, primary NPC tumors that eventually recurred were enriched for known oncogenes including BCL2 (padj = 0.000420). These findings suggest that heterogeneity in gene expression between NPC tumors play an important role in treatment response. Further work to define gene expression subtypes of NPC tumors will be helpful for patient stratification and personalized care. Citation Format: Joshua Tay, Wei Keat Teo, Chuan Keng Goh, Bing Cheng Wu, Kwok Seng Loh. Microdissected gene expression profiling of recurrent nasopharyngeal carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 774.