Abstract B014: Metabolic reprogramming in high-grade sarcomas: repurposing anti-cholesterol agents as a novel therapeutic strategy

Abstract

Abstract Introduction and Objective: Undifferentiated pleomorphic sarcoma (UPS) and leiomyosarcoma (LMS) are treated with surgery, radiation, and/or chemotherapy. Current drug therapies, such as doxorubicin, have limited response rates and severe toxicities. We performed a drug screen with over 3000 compounds on four patient-derived UPS cell lines and uncovered sensitivity to simvastatin, which inhibits the rate limiting enzyme in the mevalonate pathway. Statins are well tolerated drugs used to lower cholesterol in patients with hypercholesterolemia. The mevalonate pathway can be exploited by cancer through metabolic reprogramming and phosphoinositide 3-kinase/mammalian target of rapamycin (PI3K/mTOR) signaling to enhance proliferation. Thus, the goals of our study are to define the mechanism(s) responsible for simvastatin sensitivity and determine the efficacy when combined with doxorubicin in vivo. Hypothesis: Dysregulation of the mevalonate pathway and/or PI3K/mTOR pathway will render certain high-grade sarcomas sensitive to simvastatin. Methods: We confirmed simvastatin sensitivity in UPS, as well as in LMS cell lines, with dose-response curves. We investigated the mechanisms whereby simvastatin inhibits UPS and LMS viability with immunoblotting and flow cytometry. Proliferation was quantified using a cell proliferation dye. To assess in vivo efficacy and toxicity of simvastatin we performed a murine study with an established xenograft UPS model from our lab. We are currently assessing the efficacy of this novel combination in an LMS xenograft. Results: We found decreased phosphorylated AKT (pAKT ser473) and increased rates of active caspase-3 in most sensitive UPS cell lines with simvastatin (1uM) treatment. This indicates downregulation of PI3K/mTOR signaling and an increase in apoptosis, respectively. Importantly, these effects were rescued with the addition of mevalonate (200uM), an effector immediately downstream of the rate limiting enzyme that statins inhibit, indicating an on-target effect. In four sensitive LMS cell lines treated with simvastatin (1.5uM or 2uM) a decrease in pAKT ser473 is not consistently seen, revealing that downregulation of PI3K/mTOR signalling may not be a universal mechanism. Furthermore, in some UPS and LMS cell lines there was a significant reduction in proliferation with simvastatin + doxorubicin (0.5uM) treatment (p<0.05). Our in vivo study demonstrated that simvastatin (50mg/kg) in combination with doxorubicin (1.2mg/kg) reduced the volume of UPS tumors in mice. Furthermore, mice treated with combination therapy had higher concentrations of simvastatin and doxorubicin within the tumor than those treated with either single agent. However, this study was not designed to look at pharmacokinetics (PK), so to confirm these results a PK study is underway in an LMS xenograft. Conclusion: UPS and LMS are sensitive to simvastatin, suggesting these sarcomas rely on metabolic reprogramming to sustain viability. Thus, simvastatin may be a novel therapy for certain sarcoma patients. Citation Format: Jen Dorsey, Yael Babichev, Rosemarie E. Venier, Richard Marcellus, Rima Al-awar, Linda Z. Penn, Albiruni A. Razak, Brendan C. Dickson, Eric Chen, Irene L. Andrulis, Jay Wunder, Rebecca A. Gladdy. Metabolic reprogramming in high-grade sarcomas: repurposing anti-cholesterol agents as a novel therapeutic strategy [abstract]. In: Proceedings of the AACR Special Conference: Sarcomas; 2022 May 9-12; Montreal, QC, Canada. Philadelphia (PA): AACR; Clin Cancer Res 2022;28(18_Suppl):Abstract nr B014.