Abstract 3023: Fatty acid synthase (FASN) inhibitors synergize with carfilzomib (CFZ) in acute myeloid leukemia (AML) and multiple myeloma (MM)

Abstract Background: Fatty acid synthase (FASN) upregulation during conditions of oxidative stress contributes to tumor proliferation and survival, which appears to be a mechanism of proteasome inhibitor resistance. Here we demonstrate that acute myeloid leukemia (AML) cell lines resistant to carfilzomib (CFZ), a second-generation proteasome inhibitor, have higher basal FASN expression and targeting FASN with small molecule inhibitors enhances the cytotoxic effect of CFZ in both AML and multiple myeloma (MM) cell lines. Methods: In a proliferation assay, human AML and MM cell lines were treated with a single dose of CFZ for 7 days. Inhibition of proliferation was defined using an IC50 cutoff for CFZ of 10nM for AML and 5nM for MM as the threshold for sensitivity. Sensitive and resistant cell lines were subjected to apoptosis and cell cycle analyses by flow cytometry after being exposed to CFZ for 72 hours. Proteomic analysis was performed at baseline using reverse phase protein assay (RPPA). For CFZ and FASN inhibitor combination assays, AML and MM cell lines with varying sensitivities to CFZ were exposed to CFZ and FASN inhibitors, orlistat or TVB-3166, simultaneously, and the apoptosis rate were analyzed by flow cytometry. For western blots, selected AML and MM cell lines were incubated with compounds for 24 hours, and the lysates were probed for selected targets. Results: Single-agent CFZ induced apoptosis in sensitive AML and MM cell lines, while apoptotic rates remained low in resistant cell lines. Cell cycle analysis showed increased sub-G1 population in sensitive cell lines compared to resistant cell lines. RPPA revealed that FASN, a key enzyme involved in lipogenesis, correlated with CFZ sensitivity, and CFZ resistant lines trended towards higher basal FASN levels. When CFZ was combined with FASN inhibitors, orlistat or TVB-3166, significant synergy was observed in the apoptosis assays in the AML and MM cell lines. Western blot analyses showed FASN inhibitors enhanced the anti-proliferation and pro-apoptotic effects of CFZ. Conclusion: CFZ demonstrated single agent activity in nanomolar ranges in human AML and MM cell lines. When combined with agents targeting lipid-metabolism, CFZ showed synergistic effect in apoptosis, suggesting this combination could potentially be a new therapeutic strategy for AML and MM. Citation Format: Maoyu Peng, Sanaz Noelle Ghafouri, Martina SJ McDermott, Dennis J. Slamon, Sarah M. Larson. Fatty acid synthase (FASN) inhibitors synergize with carfilzomib (CFZ) in acute myeloid leukemia (AML) and multiple myeloma (MM) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3023.