Activating a novel cell death pathway to target PI-resistant multiple myeloma and enhance immunogenic cell death

Resistance to proteasome inhibitors (PIs) and inadequate engagement of anti-tumor immunity remain major barriers to effective treatment of multiple myeloma (MM). Here, we identified anwulignan, a bioactive natural product, as a translationally promising agent that retains activity in PI-resistant MM cells and promotes anti-myeloma immune responses. Anwulignan demonstrated potent cytotoxic activity against MM cells and exhibited strong synergy with proteasome inhibitors both in vitro and in vivo. In mouse MM models, anwulignan significantly suppressed tumor growth while maintaining favorable tolerability and safety profiles. Mechanistically, nucleophosmin 1 (NPM1) has been identified as a direct molecular target of anwulignan. Elevated NPM1 expression correlates with poor clinical outcomes in MM, and its inhibition by anwulignan induces cell cycle arrest and apoptosis. In addition to its tumor-intrinsic cytotoxic effects, anwulignan activated the caspase-1-dependent gasdermin D (GSDMD) pyroptosis pathway, thereby inducing immunogenic cell death. Genetic silencing of GSDMD markedly impaired anwulignan-mediated tumor suppression in vitro and in vivo, highlighting pyroptosis as a critical effector mechanism. In immunocompetent syngeneic MM models, anwulignan treatment increased bone marrow and splenic T-cell proportions and achieved superior tumor control compared with GSDMD-deficient tumors. Collectively, these findings establish anwulignan as a dual-function therapeutic that directly targets MM cell survival while simultaneously promoting anti-tumor immunity through pyroptosis-driven immunogenic cell death. This study provides a strong translational rationale for leveraging natural products as immune-engaging strategies to target drug-resistant multiple myeloma and improve therapeutic outcomes.