Project 2

Acute myeloid leukemia (AML) is the most common acute leukemia in adults and is a growing public health burden as the population ages. Dose-intensive induction and consolidation chemotherapy dramatically reduces tumor burden and induces clinical complete remission in the majority of individuals. However, AML patients typically relapse with chemoresistant disease and patients over 60-years-old, constituting most AML cases, exhibit dramatically worse outcomes. Thus, improved therapeutic approaches are imperative. The major overarching hypothesis of this Program Project is that increasing endogenous pro-death ceramide (Cer), while diminishing pro-survival Cer metabolites, will yield efficacious treatments for AML. Furthermore, we propose that AML patients can be risk stratified based on their sphingolipid (SL) states, which can contribute to more efficacious treatment choices. We have validated acid ceramidase (AC) as a driver of Cer detoxification to pro- survival sphingosine-1-phosphate (S1P) and established the promising, but incomplete, single-agent efficacy of AC inhibitors in AML. Our innovation & significance lie in our recent discovery that AML cell lines and patient samples stratify into distinct SL subtypes (SMhigh/low) that (a) show clear evidence of activated ceramide detoxification routes in AML and (b) establish a gene expression signature that is predictive of clinical outcome in AML. We have also identified detoxification pathways that subvert therapeutic efficacy of SL-targeting therapeutics via Cer de-acylation, phosphorylation, glycosylation, or conversion to sphingomyelin (SM). These observations form the central premise that profiling Cer detoxification pathways will inform rationally targeted blockades to drive accumulation of multiple, distinct Cer “pools.” Three specific aims will be pursued to explore the hypothesis that identification and targeting of Cer clearance routes will predict and improve outcomes in AML. Aim 1 will determine efficacy and mechanisms of AC inhibition in combination with clinically relevant AML therapeutics (venetoclax and 5'-azacytidine). These agents are known to impact SL metabolism and create vulnerabilities to combinatorial regimens that block Cer clearance. We will rationally apply Cer generators (with Project 1) and define their potency to collapse AML-specific mitochondrial rewiring (with Project 3). Aim 2 will develop strategies to optimize AC targeting and translational impact by characterizing in vivo efficacy of new AC inhibitor nanoformulations and define genes that modulate sensitivity to AC inhibition. We will also utilize gene expression profiles from SMhigh/low AML samples to predict therapeutic vulnerabilities across SL subtypes. Aim 3 will advance SL subtypes (SMhigh/low) as predictive biomarkers of clinical outcomes in AML. We will utilize clinical trial samples from patients over 60 (aged AML) to refine the predictive classifier to a reduced feature set feasible for clinical application. We will also validate the gene set predictor vs. SL levels and test the refined parameters in an independent aged AML cohort. This work will optimize AC-targeting and Cer-driven therapeutics for clinical translation and create a path to apply our SMhigh/low risk classifier for clinical management in AML. Project Number: 1P01CA302570-01 | Fiscal Year: 2025 | NIH Institute/Center: National Cancer Institute (NCI) | Principal Investigator: Thomas Loughran | Institution: UNIVERSITY OF VIRGINIA, CHARLOTTESVILLE, VA | Award Amount: $416,073 | Activity Code: P01 | Study Section: Special Emphasis Panel[ZCA1 RPRB-T (M1)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11198387