Acid ceramidase inhibition exploits sphingolipid vulnerabilities in idh mutant gliomas

Abstract The presence of the IDH mutation in gliomas is a major classifier of brain tumor subtypes and has several important implications for cancer growth. Our recent work uncovered that IDH-mutant tumors are susceptible to increased apoptosis via alterations of the sphingolipid pathway due to their excess production of pro-apoptotic ceramides over pro-proliferative sphingosine 1-phosphate (S1P). To that end, we proposed that this rheostat can be modulated to induce cell death in IDHmut tumors by targeting acid ceramidase, a critical sphingolipid enzyme in gliomas. We hypothesize that pharmacological inhibition of acid ceramidase will increase ceramide levels and therefore induce apoptosis in IDHmutgliomas. Using a preliminary drug screen, we have identified a group of haloacetate C2-ceramide derivatives known as SOBRACs that potently inhibit acid ceramidase. We selected five candidate compounds from this family and assessed the effectiveness of each drug in 3 I IDHmut (BT142, TS603, & U251mut) and 3 IDHmut (GSC923, GSC827, U251wt) patient-derived glioma cell lines, as well as non-immortalized normal human astrocytes, using the CCK8 cell viability assay. Our results indicate that the SOBRAC drugs are nearly 10 times more potent in IDH-mutant tumors compared to IDHmut cell lines. Additionally, the SOBRAC drugs are more effective than other known acid ceramidase inhibitors, making them attractive as potential novel therapeutics. To date, azide-SOBRAC is the most potent drug in the family, with EC50 value of 300 nM in BT142 cells (IDHmutmut