A mammalian, glutaminase-free asparaginase enhances venetoclax activity in preclinical AML models with chromosome 7 deletion

Introduction: Acute myeloid leukemia (AML) remains a malignancy with poor prognosis andfrequent resistance to standard therapies, underscoring the urgent need for novel treatmentstrategies. In this preclinical study, we evaluated the anti-leukemic efficacy of EBD-300, a novelmammalian-derived asparaginase lacking glutaminase activity, in combination with Venetoclax(VEN). Results: EBD-300 monotherapy exhibited significant activity in AML cell lines harboringchromosome 7/7q deletions, which are likely dependent on extracellular asparagine due to thepresence of only a single copy of the asparagine synthetase (ASNS) gene - the enzymeresponsible for endogenous asparagine synthesis. The combination of EBD-300 with VENdecreased the IC50 values of some VEN-resistant AML cell lines and reduced the colony-formingcapacity of primary AML patient samples. In patient-derived xenograft (PDX) mouse models,EBD-300, alone or in combination with VEN, significantly reduced leukemic burden in theperipheral blood, bone marrow, and spleen, and improved overall survival in one model. Discussion: Although survival benefits were observed in some, but not all, models, suggestingpotential model-specific effects, these findings collectively support a potential therapeutic roleEBD-300 in combination with VEN in AML. While weight loss was observed, EBD-300 mayrepresent a potentially safer alternative to conventional bacterial asparaginases by mitigatingthe adverse effects typically associated with the glutaminase coactivity of the bacterialasparaginases, an observation that requires further investigation.