Antileukemic effect of venetoclax and hypomethylating agents via caspase-3/GSDME-mediated pyroptosis

Background: The identifying of B-cell lymphoma 2 (Bcl-2) as a therapeutic target has led to a paradigm shift in acute myeloid leukemia (AML) treatment. Pyroptosis is a novel antitumor therapeutic mechanism due to its cytotoxic and immunogenic effects. The combination of venetoclax and hypomethylating agents (HMAs) has been shown to lead to durable responses and significantly improve prognosis in patients with AML. However, our understanding of the mechanisms underlying this combinatorial activity is evolving.

Methods: We investigated whether the Bcl-2 Inhibitor venetoclax induces AML cell Pyroptosis and identified Pyroptosis effector proteins. Via using western blotting, immunoprecipitation, RNA interference, CCK8 assays, and LDH assays, we explored the mechanism underlying the pyroptotic effect. The relationship between the expression of the Pyroptosis effector protein GSDME and AML prognosis was investigated. The effect of GSDME demethylation combined with venetoclax treatment on Pyroptosis was investigated and confirmed in mouse models and clinical samples.

Results: Venetoclax induces Pyroptosis that is mediated by caspase-3-dependent GSDME cleavage. Mechanistically, venetoclax upregulates Caspase-3 and GSDME cleavage by activating the intrinsic apoptotic pathway. GSDME is downregulated in AML by promoter methylation, and low GSDME expression is significantly associated with poor prognosis, based on public databases and patient sample analysis. In vivo and in vitro experiments showed that GSDME overexpression or HMAs-mediated restoration of GSDME expression significantly increased venetoclax-induced Pyroptosis in AML.

Conclusion: GSDME-mediated Pyroptosis may be a novel aspect of the antileukemic effect of Bcl-2 inhibitors. This finding offers new insights into potential biomarkers and therapeutic strategies, identifying an important mechanism explaining the clinical activity of venetoclax and HMAs in AML.