Cabozantinib induces NLRP3-CASP1-GSDMD-dependent pyroptosis in hepatocellular carcinoma.

[AIMS] Cabozantinib is a multi-target tyrosine kinase inhibitor approved for second-line treatment of advanced hepatocellular carcinoma (HCC). While its antiangiogenic and antiproliferative effects are well known, its immunomodulatory mechanisms remain incompletely understood. Here, we aimed to investigate the novel immunomodulatory mechanism of cabozantinib, focusing on its role in inducing pyroptotic cell death in HCC cells and myeloid-derived suppressor cells (MDSCs).

[MATERIALS AND METHODS] Cabozantinib-induced pyroptosis was evaluated in HCC cell lines and MDSCs. The involvement of the canonical NLRP3-CASP1-GSDMD pathway was validated using MDSCs induced from Nlrp3 knockout mice and Gsdmd knockout HCC cells. In vivo efficacy and immunomodulation were assessed using Gsdmd knockout Hepa1-6 tumors in immunocompetent mice, analyzed via flow cytometry, single-cell RNA sequencing, and phosphoproteomics.

[KEY FINDINGS] We show that cabozantinib induces pyroptotic cell death in both HCC cells and MDSCs via the canonical NLRP3-CASP1-GSDMD pathway. Disruption of this pathway using MDSCs induced from Nlrp3 knockout mice or Gsdmd knockout HCC cells abrogated cabozantinib-induced pyroptosis. Critically, implantation of Gsdmd knockout tumors in vivo abolished the antitumor and immunomodulatory effects of cabozantinib, confirming the necessity of GSDMD-mediated pyroptosis. Furthermore, cabozantinib reduced MDSC accumulation and enhanced cytotoxic CD8 T cell responses, findings further supported by phosphoproteomic analysis showing pyroptosis-associated signaling alterations.

[SIGNIFICANCE] These findings reveal a mechanistic link between cabozantinib-induced pyroptosis and immune activation. Our results provide a strong rationale for the clinical combination of cabozantinib with immunotherapy in the treatment of HCC.