A1136
Title: Spatial transcriptomics reveals gene programs of plasma cell rich lymphomyeloid aggregates in ovarian cancer
Authors: Shreena Nisha Kalaria - Deeley Research Centre at BC Cancer Victoria (Canada) [presenting]
Celine M Laumont - Deeley Research Centre at BC Cancer Victoria (Canada)
Farouk Nathoo - University of Victoria (Canada)
Brad Nelson - BC Cancer (Canada)
Abstract: Plasma cells are emerging as prognostic markers in high-grade serous ovarian cancer (HGSC), yet their spatial organization and transcriptional states within the tumour microenvironment remain poorly characterized. In particular, plasma cell-rich lymphomyeloid aggregates (LMAs) - dense immune cell regions in which plasma cells dominate - are potentially important sites of anti-tumour activity. A modified 10x Genomics Visium workflow is used to obtain spatially resolved gene expression and B-cell receptor (BCR) data from 14 HGSC tumours. Plasma cell-rich LMAs were identified via kernel density estimation, and their transcriptional landscapes were characterized using negative binomial differential expression tests. Three predominant transcriptional programs emerged: a ribosomal-low state, an extracellular matrix remodelling state, and an innate immunity activation state. These likely represent distinct functional states. Preliminary analyses suggest that plasma cell-rich LMAs may exhibit distinct proximities to epithelial structures compared with other immune aggregates, as well as unique combinations of BCR receptors. These relationships will be quantified, and their reproducibility will be assessed in external datasets. Findings demonstrate how integrating spatial statistics with transcriptomic profiling can reveal the heterogeneity of immune microenvironments in HGSC, laying the groundwork for understanding their therapeutic relevance.
