Project Summary/Abstract Lysosomal proteolysis facilitates the turnover of organelles and selected long-lived proteins and is a critical regulator of cellular homeostasis. Its aberrant activation promotes drug resistance and cancer progression by generating alternative sources of survival sustaining metabolic fuel to cells that are stressed by hypoxia, radiation, chemotherapy, and targeted agents. Despite its clear potential as a therapeutic target, no intentionally designed targeted inhibitors of lysosomal function have been FDA approved to date. We recently generated a series of novel orally available lysosomal disrupting agents with favorable safety profiles and single agent therapeutic activity. Our first lead hit is active against acute myeloid leukemia (AML) cells with high-risk features and augments the efficacy of azacitidine to significantly extend overall survival in mouse models of AML. Our major goal is to use medicinal chemistry approaches to optimize its pharmacologic properties to develop a novel lysosomal proteolysis inhibitor that can be commercialized for the treatment of patients with AML and other diseases where aberrant pathway activity contributes to pathogenesis.