Enhanced Mitochondrial Priming By Momelotinib Confers Superior In Vivo Efficacy in Combination with Venetoclax Compared to Gilteritinib or Ruxolitinib

Introduction. Acute Myeloid Leukemia (AML) is a complex hematologic malignancy marked by significant genetic heterogeneity, with FLT3 mutations being among the most common and prognostically unfavorable alterations. Despite advancements in targeted therapies, FLT3-mutated AML remains a significant challenge due to frequent relapses and resistance to existing treatments. Targeting mitochondrial apoptosis pathways has emerged as a promising strategy to enhance therapeutic efficacy. Proteomic and signaling studies have revealed that Momelotinib enhances mitochondrial priming in AML cells, irrespective of FLT3 mutational status. Consequently, Momelotinib treatment exhibits superior efficacy when combined with Venetoclax, compared to combinations with Gilteritinib or Ruxolitinib. Preclinical evaluations of Gilteritinib and Ruxolitinib in combination with BCL2 inhibitors have been limited to FLT3 and JAK2 mutant cases, respectively. In contrast, Momelotinib has demonstrated a synergistic response across all AML genotypes. Result. Mitochondrial priming is a major determinant of therapeutic outcome in FLT3 mutated AML treated with BCL2 inhibitors. BH3 profiling of AML cells with and without FLT3 mutations reveled that momelotinib treatment enhances mitochondrial priming in AML regardless of FLT3 mutational status. In contrast, treatment with Gilteritinib or Ruxolitinib showed minimal change on mitochondrial priming. Our findings indicate that Momelotinib significantly enhances mitochondrial priming, leading to increased apoptosis and reduced leukemic cell viability when used in combination with Venetoclax. In FLT3-mutated AML cell lines and primary patient samples, the Momelotinib+Venetoclax combination exhibited superior response than Gilteritinib+Ventoclax combination. Strikingly, Momelotinib+Venetoclax showed effective suppression of non-FLT3 mutated AML while treatment with Gilteritinib+Ventoclax were ineffective against these cells. In vivo studies utilizing xenograft models of FLT3-mutated AML cells from cell lines and primary patient samples demonstrated that the Momelotinib-Venetoclax combination achieved superior leukemic clearance and prolonged survival. In conclusion, our study underscores the potent synergistic effect of Momelotinib and Venetoclax in AML regardless of FLT3 mutational status, attributable to enhanced mitochondrial priming. These findings provide a compelling rationale for the clinical evaluation of Momelotinib and Venetoclax combination therapy, highlighting its potential to improve treatment outcomes in patients with high-risk AML.