CNSC-03. 4-ACETYLANTROQUINONOL B FROM ANTRODIA CINNAMOMEA SUPPRESSES GLIOBLASTOMA AND ENHANCES NK CELL-MEDIATED CYTOTOXICITY WITH SYNERGISTIC ANTITUMOR EFFECTS

Abstract BACKGROUND Glioblastoma (GBM) remains highly refractory to treatment, with rapid recurrence following surgery and chemo-radiation therapy, compounded by profound natural killer (NK) cell dysfunction. Adoptive NK cell transfer has emerged as a promising immunotherapeutic strategy for GBM and is currently undergoing clinical evaluation. However, its efficacy is hampered by a suppressive tumor microenvironment, limited NK cell infiltration, and metabolic exhaustion. METHODS 4-Acetylantroquinonol B (4-AAQB), a ubiquinone derivative isolated from Antrodia cinnamomea, possesses known anti-tumor and anti-inflammatory properties. We hypothesized that 4-AAQB could restore or enhance NK cell function against GBM. To test this, we evaluated the effects of 4-AAQB on the cytotoxicity of NK-92 cells against human GBM lines using NK cytotoxicity assays. Flow cytometry and qRT-PCR were employed to examine the expression of cytotoxic mediators, activating receptors, and signaling molecules. RESULTS Our results demonstrate that 4-AAQB significantly enhances NK-92-mediated cytotoxicity against GBM cells without impacting normal MRC5 fibroblasts. This effect correlated with increased expression of cytotoxic granules and activating receptors. In a GBM xenograft model, both 4-AAQB and NK-92 cells individually suppressed tumor growth, while their combination resulted in a synergistic anti-tumor effect without evidence of hepatotoxicity or nephrotoxicity. Bulk RNA sequencing of excised tumors revealed 199 differentially expressed genes unique to the combination therapy, over 80% of which were not shared with either monotherapy. These changes reflected synergistic transcriptional reprogramming, including upregulation of genes involved in apoptotic cell clearance and NK cell maturation, and downregulation of key tumor survival and resistance pathways. Pathway analysis further indicated suppression of autophagy and mitophagy—protective mechanisms in GBM—suggesting that 4-AAQB sensitizes GBM cells to immune-mediated apoptosis by dismantling intrinsic survival circuits. CONCLUSION Collectively, these findings identify 4-AAQB as a first-in-class, orally deliverable NK cell immunotherapy enhancer for GBM and support its further translational development.