HMGA2 Expression Predicts Subtype, Survival, and Treatment Outcome in Pancreatic Ductal Adenocarcinoma.

Purpose: The purpose of this study was to establish HMGA2 as a marker of basal-like disease in pancreatic ductal adenocarcinoma (PDAC) and explore its use as a biomarker for prognosis and treatment resistance.

Experimental design: We identified high-mobility group A2 (HMGA2) protein expression in basal PDAC cells in a single-cell RNA sequencing (RNA-seq) atlas of 172 patient samples. We then analyzed HMGA2 expression, along with expression of the classic marker GATA-binding factor 6 (GATA6), in a cohort of 580 PDAC samples with multiplex IHC. We further supplemented these data with an additional 30 diverse patient samples and multiple independent single-cell RNA-seq databases.

Results: We found that expression of HMGA2, but not previously described basal markers cytokeratins 5 or 17, predicted overall survival in our cohort. Combining HMGA2 and GATA6 statuses allowed for the identification of two key study groups: an HMGA2+/GATA6- cohort with worse survival, low tumor-infiltrating CD8+ T cells, increased FAP+ fibroblasts, and poorer response to gemcitabine-based chemotherapies (n = 94, median survival = 11.2 months after surgery) and an HMGA2-/GATA6+ cohort with improved survival, increased CD8+ T-cell infiltrate, decreased FAP+ fibroblasts, and improved survival with gemcitabine-based chemotherapy (n = 198, median survival = 21.7 months after surgery). HMGA2 was also prognostic for overall survival in RNA-seq from an independent cohort.

Conclusions: IHC stratification of primary tumors by HMGA2 and GATA6 statuses in pancreatic cancer is associated with differential outcomes, survival following chemotherapy, and tumor microenvironments. As a nuclear marker for basal disease, HMGA2 complements GATA6 to identify disease subtypes in PDAC.