P435: NOVEL COMPOUNDS TO TARGET KMT2A-REARRANGED PEDIATRIC ACUTE MYELOID LEUKEMIA

• DOI: 10.1097/01.hs9.0000968648.65688.ee
• Publication Date: 2023-08-08T16:01:38Z
• Authors: Claudia Tregnago; Maddalena Benetton; Ambra Da Ros; Giulia Borella; Giorgia Longo; Katia Polato; Jolanda Sabatino; Giovanni DI Salvo; Franco Locatelli; Martina Pigazzi
• Keywords: Ex vivo; Decitabine

Background: In pediatric acute myeloid leukemia (AML), fusions involving lysine methyltransferase 2A (KMT2A) are considered hallmarks of aggressive AML, representing a challenge for the development targeted specific therapeutic agents to ameliorate classic chemotherapy and obtain complete eradication disease. Among them, t(9;11)KMT2A::MLLT3 represents most recurrent rearrangement, whereas t(6;11)KMT2A::AFDN-r is associated with dismal prognosis below 25%. We previously described KMT2A-AFDN mediating peculiar gene expression, hyper activation MAPK signaling marked adhesion properties. Through high-throughput drug screening (HTS) we identified thioridazine (TDZ) as an efficacious compound, but its use limited by huge blood brain barriers crossing cardiotoxic effects. Aims: generated novel compound treat KMT2A-AFDN-r AML find promising strategies KMT2A-r AML. Methods: investigated levels BCL-2, phospho-BCL-2 S70 MCL-1 in cohort 66 patients analyzed Reverse Phase Protein Array. selected KMT2A-specific drugs resulted from performed HTS. To overcome cytotoxic effects TDZ, synthesized analogous namely TDZ6 chemically modifying molecule structure increase branching polarity. validated combinations cell lines ex vivo primary cells three-dimensional (3D) scaffold seeded mesenchymal stromal mimicking bone marrow niche vivo. Results: found that 75% distributed Q3+Q4 quartiles BCL-2 high well, indicating anti-apoptotic pathway activation. attempt target it, tested venetoclax (VEN), BCL- 2 inhibitor, drugs, revealing Bromodomain Extra-Terminal Domain (BET) inhibitor I-BET151, kinase sunitinib, decreased family protein expression synergized VEN enhancing death, also 3D model. Regarding KMT2A-AFDN, maintained activity on ex-vivo PDX cells, IC50 <10µM. The combination VEN, both acting mitochondria, synergistic through strong mitochondrial depolarization triggered blasts apoptosis (ZIP-synergy score 22.2; Combination Index 0.83), confirmed vivo, NSG mice KMT2A-AFDN-AML line flank injection (8mg/kg i.p.), it was not pilot study one AML-PDX. Thus, increased TDZ dose, showing at 70 mg/kg i.p. (46% reduction) maximum tolerated dose. documented this latter dose devoid effects, revealed QTc measurement during electrocardiogram, 12 (p<0.00006, ctr: 77.9msec, TDZ6: 75.7msec, TDZ: 93.7msec). Summary/Conclusion: Overall, KMT2A-selective together converging different all apoptotic networks activation, supporting setting. demonstrate reduces growth vitro enlarged will support efficacy safety. This highlights importance having bona-fide model test produce reliable results, accelerate introduction therapies life-threatening KMT2A-AML subgroup Keywords: Venetoclax, KMT2A, Acute leukemia, BCL2