Abstract 1844: Proteomic characterization of decitabine resistance in acute myeloid leukemia reveals signaling pathway crosstalk dampens the effectiveness of combination therapy

Abstract Acute myeloid leukemia (AML) is a deadly form of blood cancer primarily characterized by genetic abnormalities that guide treatment strategies. In recent years, several new therapies have emerged to target these genetic abnormalities such as gilteritinib or quizartinib, which target an internal tandem duplication (ITD) of the FLT3 gene. Additional drugs have been developed to target core cellular processes, such as venetoclax and the decitabine. Despite initial positive responses to these treatments, patients eventually relapse as they develop resistance to the individual drugs. One common approach to drug resistance is to add an additional drug to the treatment protocol. However, patients then develop further resistance to not just a single drug but multiple. As such, understanding the origins of both single and multi-drug resistance is crucial for improving treatment efficacy and clinical outcomes. Here, we present a collection of cell lines that have developed resistance to single, double, and triple drug combinations of gilteritinib, venetoclax, and decitabine. Through comprehensive global and phospho proteomics analyses under multiple conditions together with computational pathway interrogation, we unravel the underlying molecular mechanisms responsible for resistance. Leveraging our previous model of early and late drug resistance, we investigate the emergence of resistance to drug combinations involving gilteritinib alone, gilteritinib with venetoclax, gilteritinib with decitabine, and gilteritinib with venetoclax and decitabine. Through the characterization of molecular signatures for each drug combination, we identify molecular signals that are specific to combination treatments. Specifically, we find that the emergences of decitabine resistance alters the cellular pathways to effectively downregulate targets of venetoclax and gilteritinib, ultimately dampening the response to these drugs, regardless of co-administration. These findings provide a potential explanation for the limited success of combination treatments involving hypomethylating agents, as observed in recent clinical trials. Our results underscore the importance of monitoring proteome-level changes in single and combination drug treatments and shed light on the simple and intuitive reasons behind the lack of synergy often observed in combination therapies. In conclusion, we establish cell line models of resistance to various combinations of venetoclax, gilteritinib, and decitabine. By integrating global and phospo proteomic measurements, we gain a comprehensive understanding of the intricate molecular mechanisms underlying resistance. Citation Format: James C. Pino, Camilo Posso, Setareh Sharzehi, Sara Gosline, Chelsea Hutchinson-Bunch, Elie Traer, Paul D. Piehowski, Karin D. D. Rodland, Jeffrey W. Tyner, Tao Liu, Anupriya Agarwal. Proteomic characterization of decitabine resistance in acute myeloid leukemia reveals signaling pathway crosstalk dampens the effectiveness of combination therapy abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 1844.