Understanding the molecular pathogenesis of acute myeloid leukemia (AML) with well-defined genomic abnormalities has facilitated the development of targeted therapeutics. Patients with t(8;21) AML frequently harbor a fusion gene RUNX1-RUNX1T1 and KIT mutations as “secondary hit”, making the disease one of the ideal models for exploring targeted treatment options in AML. In this study we investigated the combination therapy of agents targeting RUNX1-RUNX1T1 and KIT in the treatment of t(8;21) AML with KIT mutations. We showed that the combination of eriocalyxin B (EriB) and homoharringtonine (HHT) exerted synergistic therapeutic effects by dual inhibition of RUNX1-RUNX1T1 and KIT proteins in Kasumi-1 and SKNO-1 cells in vitro. In Kasumi-1 cells, the combination of EriB and HHT could perturb the RUNX1-RUNX1T1-responsible transcriptional network by destabilizing RUNX1-RUNX1T1 transcription factor complex (AETFC), forcing RUNX1-RUNX1T1 leaving from the chromatin, triggering cell cycle arrest and apoptosis. Meanwhile, EriB combined with HHT activated JNK signaling, resulting in the eventual degradation of RUNX1-RUNX1T1 by caspase-3. In addition, HHT and EriB inhibited NF-κB pathway through blocking p65 nuclear translocation in two different manners, to synergistically interfere with the transcription of KIT . In mice co-expressing RUNX1-RUNX1T1 and KIT N822K , co-administration of EriB and HHT significantly prolonged survival of the mice by targeting CD34 + CD38 − leukemic cells. The synergistic effects of the two drugs were also observed in bone marrow mononuclear cells (BMMCs) of t(8;21) AML patients. Collectively, this study reveals the synergistic mechanism of the combination regimen of EriB and HHT in t(8;21) AML, providing new insight into optimizing targeted treatment of AML.

Internal tandem duplication mutations of the FMS-like tyrosine kinase-3 (FLT3-ITDs) occur in 25%-30% of patients with acute myeloid leukemia (AML) and are associated with dismal prognosis. Although FLT3 inhibitors have demonstrated initial clinical efficacy, the overall outcome of patients with FLT3-ITD AML remains poor, highlighting the urgency to develop more effective treatment strategies. In this study, we reveal that FLT3 inhibitors reduced protein stability of the anti-cancer protein p53, resulting in drug resistance. Blocking p53 degradation with proteasome inhibitors restores intracellular p53 protein levels and, in combination with FLT3-ITD inhibitors, shows superior therapeutic effects against FLT3-ITD AML in cells, mouse models, and patients. These data suggest that this combinatorial therapeutic approach may represent a promising strategy to target FLT3-ITD AML.

The partial tandem duplication of histone-lysine N-methyltransferase 2A (KMT2A-PTD) is an important genetic alteration in acute myeloid leukemia (AML) and is associated with poor clinical outcome. Accurate and rapid detection of KMT2A-PTD is important for outcome prediction and clinical management, but next-generation sequencing-based quantitative research is still lacking. In this study, we developed a targeted RNA-based next-generation sequencing panel, together with single primer enrichment and unique molecular identifiers, to identify KMT2A-PTD as well as AML-related gene fusions and other driver mutations. Our panel showed high sensitivity, accuracy, and reproducibility in detecting the fusion ratio of KMT2A-PTD. The mutation profile of KMT2A-PTD-positive patients with AML was characterized and different distribution patterns of driver mutations were found according to KMT2A-PTD fusion ratio level. Survival analyses revealed that the fusion ratio of KMT2A-PTD did not affect clinical outcome, but a novel molecular combination, namely, KMT2A-PTD/DNMT3A/FMS-Like tyrosine kinase 3-internal tandem duplication, was associated with poor prognosis. Finally, it was shown that the dynamic changes in the KMT2A-PTD fusion ratio were consistent with the overall process of disease progression. In summary, we applied the unique molecular identifier-based RNA panel to quantitatively detect KMT2A-PTD and elucidate its clinical relevance, which complemented the integrative network of various genetic alterations in AML.

Chromosomal translocations and generating fusion genes are closely associated with disease initiation and progression in acute myeloid leukemia (AML). In this study, we identified a novel t(X;17)(q28;q21) chromosomal rearrangement in a patient with acute monocytic leukemia. Using RNA-sequencing, we identified a KANSL1-MTCP1 and a KANSL1-CMC4 fusion gene. 5'-UTR sequences of the KANSL1 gene were found to become fused upstream of the coding sequence region of the MTCP1 and CMC4 genes, respectively, resulting in an aberrantly high expression of these genes. Functional studies revealed that overexpression of the MTCP1 gene induced an increased cell proliferation and partial blockage of cell differentiation, suggesting that the aberrant expression of MTCP1 is of critical importance in leukemogenesis.