BIOM-56. HEAT SHOCK PROTEINS PREDICT CLINICAL RESPONSE AND POTENTIATE LOCAL IMMUNOGENICITY AFTER LITT FOR GLIOBLASTOMA

Abstract Glioblastoma (GBM) remains one of the deadliest cancers despite advances in therapies. Laser interstitial thermal therapy (LITT) is a minimally invasive technique used to ablate intra-axial brain tumors. Non-ablative LITT-induced hyperthermia (33-43˚C) increases intra-tumoral mutational burden and neoantigen production, promoting neoantigen presentation via heat shock proteins (HSPs). HSPs are protein-folding chaperones that present novel intracellular antigens for immune recognition. We investigated HSPs as predictors of local immune response and clinical outcomes of GBM patients undergoing LITT. We conducted immune deconvolution of bulk RNA-sequencing data from The Cancer Genome Atlas to determine the correlation between 97 unique HSPs and tumor infiltration of CD8+, CD4+, B, macrophage, neutrophil, and dendritic cells. We evaluated the association between HSP expression and overall survival (OS). Pre-LITT biopsies from 9 patients (responders and non-responders) were analyzed via immunohistochemistry (IHC) to identify spatial HSP expression. Next-generation sequencing was utilized to validate findings and identify other predictive biomarkers. We identified two HSPs for further investigation: SACS and HSPA5. SACS was associated with improved survival based on TCGA data (14.9 vs. 11 months, HR:1.3, p<0.0001). HSPA5 was associated with worse outcomes (12.1 vs. 15.0 months, HR:0.73, p<0.0001). Immune deconvolution showed HSPA5 positively correlated with dendritic cell infiltration (r=0.50, p=6.1E-27) and SACS with CD8+ infiltration (r=0.31, p=6.8E-11). IHC of 9 patients demonstrated high SACS expression was associated with improved OS (p<0.05) after LITT. Multiplex IHC illustrated that immune cell infiltration was associated with therapeutic response post-LITT. Our ongoing immunohistochemical and genomic analyses aim to clarify the role of HSPs in enhancing immunogenicity in GBM. Further investigation into SACS and immune cell infiltration may reveal how hyperthermia via LITT improves response through neoantigen presentation.