Targeting Ceramide Metabolism in AML

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AML is a heterogeneous group of malignant disorders whose primary therapy has changed little in recent decades. Sphingolipid metabolism, centered on the pro-apoptotic molecule ceramide, represents an understudied therapeutic avenue in this and other malignancies. This project stems from the hypothesis that ceramide-based therapeutics can be utilized as selective and sensitive anti-cancer agents. Unfortunately, the potential of ceramide-based therapeutics is severely limited by cell-impermeability and hydrophobicity. We have pioneered the use of nanotechnology to turn ceramide from a hydrophobic agent into a hydrophilic drug, engineering a C6-ceramide nanoliposome with clear efficacy in cancer models. Preliminary data suggest that ceramide nanoliposomes are active in multiple AML cell lines and primary cases, but sensitivity is highly variable. Thus, the goal of the project is the design of second-generation ceramide nanoliposomes that exert efficacy in AML patients who are resistant to conventional chemotherapy. In Specific Aim 1, we will optimize second-generation nanoliposomal ceramide therapy for the treatment of AML. To maximize efficacy, ceramide nanoliposomes will be re-engineered via encapsulation of pharmacological agents to inhibit ceramide metabolism or autophagy. We will also actively target ceramide nanoliposomes to AML progenitor populations, initially via conjugation of anti-CD117 (c-kit), which is preferentially expressed in hematopoitic stem cells. In Specific Aim 2, we will investigate mechanisms underlying the enhanced efficacy between ceramide nanoliposomes and pharmacological agents that inhibit ceramide metabolism or autophagy. Specifically, based upon preliminary data, we will investigate if this synergism is mediated via a molecular-based switch from autophagy to apoptosis and/or a synergistic elevation of long chain pro-apoptotic ceramide species. We will also characterize the contribution of selective ceramide synthases to the elevation of long chain ceramide species in defined AML patient subtypes. With the indispensable support of programmatic projects and cores, this project will rapidly characterize and validate the efficacy of second-generation ceramide nanoliposomes in defined AML populations. RELEVANCE (See instructions): Acute myelogenous leukemia (AML) is biologically heterogeneous and exhibits significant variability in sphingolipid metabolism. Current therapy of AML is highly toxic and yields variable and ultimately inadequate outcomes. Additional therapeutic options are necessary for AML. The present project engineers, characterizes and validates second-generation ceramide nanoliposomes as selective and sensitive therapeutics in AML patients in poor prognostic categories. State of the art in-vivo models of AML blasts will allow assessment of ceramide-based therapeutics.