Discovery of Novel MLKL PROTAC Degraders for the Treatment of Hepatocellular Carcinoma via Promoting Parthanatos

Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related mortality worldwide, primarily due to its low immunogenicity and immunosuppressive tumor microenvironment. Inducing immunogenic cell death (ICD), a regulated form of cell death with the capacity to enhance tumor immunogenicity and activate antitumor immune responses, has emerged as a pivotal anticancer strategy. Mixed lineage kinase domain-like pseudokinase (MLKL) is a terminal-known obligate effector in the process of necroptosis, a programmed cell death pathway. Although several ATP competitive inhibitors of MLKL were reported, these inhibitors were unable to prevent the function of MLKL, rendering MLKL seemingly "undruggable." Moreover, the majority of research on MLKL focused on its biological role in necroptosis, and the investigation of its non-necroptotic functions has rarely been reported. Here, we report the discovery of C116 as a potent and selective MLKL degrader through leveraging artificial intelligence-assisted ligand discovery combined with targeted protein degradation technology. Notably, C116 effectively induces MLKL degradation and promotes parthanatos in HCC cells. More importantly, C116 was able to induce in vivo MLKL degradation and exerts strong antitumor activities in an orthotopic HCC tumor model, positioning it as a promising starting point for the treatment of HCC and for investigating the non-necroptotic functions of MLKL.