A Dual PI3K/HDAC Inhibitor Induces Immunogenic Ferroptosis to Potentiate Cancer Immune Checkpoint Therapy.

The capacity of targeted anticancer agents to exert immunomodulatory effects provides a strong rationale to develop novel agents suitable for combinatorial regimens with immunotherapy to improve clinical outcomes. In this study, we developed a dual-targeting PI3K and HDAC inhibitor BEBT-908 that potently inhibits tumor cell growth and potentiates anti-PD1 therapy in mice by inducing immunogenic ferroptosis in cancer cells. Treatment with BEBT-908 promoted ferroptotic cell death of cancer cells by hyperacetylating p53 and facilitating the expression of ferroptotic signaling. Furthermore, BEBT-908 promoted a proinflammatory tumor microenvironment that activated host antitumor immune responses and potentiated immune checkpoint blockade therapy. Mechanistically, BEBT-908-induced ferroptosis led to upregulation of MHC class I and activation of endogenous IFNγ signaling in cancer cells via the STAT1 signaling pathway. The dual PI3K/HDAC inhibitor BEBT-908 is a promising targeted therapeutic agent against multiple cancer types that promotes immunogenic ferroptosis and enhances the efficacy of immunotherapy. SIGNIFICANCE: The dual PI3K/HDAC inhibitor BEBT-908 elicits potent antitumor responses, effectively inducing immunogenic ferroptosis of tumor cells and potentiating cancer immunotherapy. ©2021 American Association for Cancer Research.