KMT2A expression

Human KMT2A-r AML cells could be pharmacologically sensitized to NKG2D-CAR T cells by treatment with the histone deacetylase inhibitor LBH589 (panobinostat) which caused upregulation of NKG2D-ligand levels...Finally, the results were validated and extended to acute leukemia in infancy. Combined, activating mutations induced mutation-specific changes in the epigenetic landscape, leading to changes in transcriptional programs orchestrated by specific transcription factor networks.

To date, this new class of drugs has been tested in phase I and II clinical trials, both alone and in combination with synergistic drugs showing promising results in terms of response rates and safety in heavily pre-treated acute leukemia patients. In this brief review, we summarize the key findings on menin inhibitors, focusing on the mechanism of action and preliminary clinical data on the treatment of acute myeloid leukemia with this promising new class of agents, particularly revumenib and ziftomenib.

Integrating the proteome of pre-leukemic cells with their secretome and the proteomic composition of the extracellular environment of normal progenitors highlights differential regulation of Igf2 bioavailability, as well as of VLA-4 dimer and its ligandome, upon initiation of fetal- and adult-origin leukemia, with implications for human MLLr leukemia cells' ability to communicate with their environment through granule proteins. Our study has uncovered opportunities for targeting ontogeny-specific proteomic vulnerabilities in in utero-initiated and adult-onset MLLr leukemia.

Only 2 B-ALLs with KMT2A-r showed NG2 expression below 10%, probably due to the steroid therapy administered prior to cytofluorimetric analysis.Compared to KMT2A-r-cases, KMT2A r+ B-ALLs showed a higher blast percentage, significantly higher mean fluorescence intensity (MFI) of CD45, CD38, and CD58, and significantly lower MFI of CD34, CD22, TdT, and CD123.The study confirmed differences in CD45, CD34, CD22, and TdT MFI within the same immunologic EGIL group (European Group for the immunological classification of leukemias), indicating no influence of the B-ALLs EGIL subtype on the KMT2A-r+ B-ALLs immunophenotype. Our data demonstrate the association between NG2 and KMT2A-r in B-ALLs identify a distinctive immunophenotypic pattern, useful for rapid identification in diagnostic routines of these subtypes of B-ALLs with a poor prognosis that benefits from a specific therapeutic approach.

Dual inhibition of RET and CDK8 restricted cell proliferation by producing multimodal oxidative stress responses in treated cells. Our data suggest that epigenetically enhanced RET protects KMT2A-r AML cells from oxidative stresses, which could be exploited as a potential therapeutic strategy.

This identifies and validates a cell-intrinsic mechanism whereby selective disruption of proteostasis results in altered transcription factor abundance and repression of oncogene-specific transcriptional networks. These data demonstrate that the immunoproteasome is a relevant therapeutic target in AML and that targeting the immunoproteasome in combination with Menin-inhibition could be a novel approach for treatment of KMT2A-r AML.

KMT2Ar-AML has been demonstrated to be sensitive to BCL2 inhibitor venetoclax (VEN), but these patients are unable to benefit from current VEN-based regimen (VEN plus azacitidine or low dose-cytarabine), so a novel and KMT2A rearrangement-specific targeting partner is required, and MENIN inhibitor (MEN1i) is a promising one. Hypoxia induction sensitized KMT2Ar-AML to VEN plus MI-503-mediated proliferation inhibition and apoptosis induction. Therefore, repressing HIF-1A-induced HDAC9 contributed to the synergistic effect of VEN and MEN1i in KMT2Ar-AML.

Upon engraftment, recipients were subjected to different treatments, including chemotherapy (cytarabine for 5 days+doxorubicin for 3 days), the FLT3 inhibitor AC220, chemotherapy followed by AC220, or AC220+Trametinib, a MEK inhibitor. Taken together, the treatment given affected survival and impacted evolution of the FLT3 N676K-leukemia cells. The general absence of acquired mutations in most mice suggests that target-independent mechanisms may underline acquired resistance in most mice, and we propose the Six1/Wnt/ß-catenin axis as a potential vulnerability upon AC220-resistance.

LSD1 Inhibitor ladademstat in Combination with Menin Inhibitor revumenib has synergistic effect in KMT2A-Rearranged AML models. Surprisingly, we also found that PSIP1, which is essential for inducing MLL-rearranged leukemia, interacts with LSD1. This suggests that PSIP1 may modulate gene expression through its ability to interact with both MLL1 and LSD1.

Given the results obtained with menin inhibitors in KMT2A-rearranged and NPM1-mutated AML, our findings open an opportunity for exploiting a therapeutic vulnerability in all HOX-AML including KMT2A-PTD AML or AML with high MEN1 expression. Since HOX-AML highly express genes according to the HOX differentiation profile, stage-specific surface proteins coded by these genes would be promising targets.

We performed cell viability experiments on leukemia cell lines (MV4; 11, MOLM13, RS4; 11, THP1, SEM, KOPN8, NOMO1, HL60, ML2) with single, two and three drug combinations using a menin inhibitor (VTP50469), a DOT1L inhibitor (EPZ5676), and a CDK9 inhibitor (AZD4573). Based on our preclinical in vitro findings, the co-inhibition of menin-DOT1L or menin-CDK9 is a promising approach for the treatment of MLL-r leukemia. The varying responses of different MLL-r leukemia cell lines to drug combination treatment indicate that not all cases of MLL-r leukemia will respond uniformly to treatment combinations. Taken together, our data provide a strategy to determine optimal treatment combinations for personalized treatment of MLL-r leukemia.

Mechanistically, KMT2A activated the translocation of β-catenin into the nucleus of gastric cancer cells, and then, β-catenin served as a coactivator of KLF11, which promoted the expression of specific gastric cancer stemness-related molecules, including SOX2 and FOXM1. Together, KMT2A is an important epigenetic regulator of gastric cancer stemness, which provides a novel insight to the potential application of targeting against KMT2A in treating gastric cancer.

Together, we suggest that targeting ASH2L could serve as a new therapeutic opportunity for glioblastoma. Video Abstract.

Differential expression analyses of the mRNA-seq data led to clustering of this case with other hyperdiploid cases, consistent with the hyperdiploid cytogenetic results. Given the additional intensity and potential toxicity of high-risk treatment, unusual findings by chromosome analysis, FISH and/or chromosomal microarray should prompt consideration of testing for a KMT2A fusion by another method to avoid misclassification.

The inhibitors suppressed expression of MLL target genes HoxA9, Meis1 and Myc, and selectively inhibited proliferation of MLL-r and other acute myeloid leukemia cells with EC values as low as 4.7 μM. These inhibitors are useful chemical probes for biological studies of AF9/ENL, as well as pharmacological leads for further drug development against MLL-r and other leukemias.

Some SMO inhibitors have been tested in clinical trial and Glasdegib is FDA approved in combination with low dose cytarabine in elderly patients. Given the success of generating these two point mutations, we are currently generating more RAS pathway mutations, including other KRAS mutations, PNTP11 and NF1 mutations. Conclusion These experiments showed: 1) It is possible to induce 2 oncogenic hits in human primary cells and get leukemia in vivo; 2) the KRAS G13D and NRAS G12D mutations shorten the latency of the disease and 3) increase the LSC frequency in secondary mice; 4) a possible involvement of the Hh pathway on stemness/LSC in RAS mutated cells; 5) our experimental approach is robust and very promising to decipher the RAS pathway in human MLL leukemias.

We utilized genetic and pharmacological (mycophenolate mofetil, MMF, a purine biosynthesis inhibitor of IMPDH) approaches to target the enhanced purine metabolism and found inhibition of the purine synthesis pathway promotes myeloid differentiation of both murine and human LSCs...Moreover, we found that the myeloid differentiation induced by MMF or CX-5461 is associated with reduced chromatin occupancy of the MLL-AF9 complex, especially Menin, and downregulated expression of MLL-AF9 target genes, such as Meis1, Hoxa9, and Myc, suggesting a regulatory role of nucleolar rRNA transcription on MLL-AF9 oncogenic gene expression program...Altogether, our findings reveal that purine metabolism maintains nucleolar rRNA transcription homeostasis to modulate MLL fusion complex-induced leukemogenic transcriptional activity in LSCs. The enhanced purine metabolism emerges as a crucial dependency for LSCs, providing potential targets for novel therapeutic strategies in treating MLL-rearranged leukemia.

Study confirmed that MLL-rearranged ALL cells are highly sensitive to the broad-spectrum HDAC inhibitor panobinostat. Furthermore, when exploring therapeutic options for targeting MLLr-AML, we found that combining the BCL-2 inhibitor Venetoclax (VEN) with an MLL-Menin specific inhibitor (MEN1i) specifically downregulated the expression of HDAC9 and had a favorable synergistic killing effect on MLLr-AML in both in vitro and in vivo models, further suggesting an important role of HDAC9 in the treatment of MLLr-AML. To sum up, through this study, we can shed light on the role of specific HDAC molecules in MLLr-AML and provide a new potential target for the degradation of MLL fusion protein to eradicate MLLr-AML.

Macrophage depletion by clodronate liposomes did not affect the in vivo expansion of H2-K1 sgRNA-expressing leukemia cells demonstrating that macrophages were not suppressed by H2-K1 on the leukemia cells...H2-K1 alters the maturation and activation of NK cells in the bone marrow niche. These findings increase our understanding of how leukemia cells escape immune surveillance and suggest that the identification of corresponding mechanisms in human AML could pave the way for new therapies that boost the endogenous NK cells by restoring immune surveillance mechanisms.

Here we describe CLEC2A, a novel AML-restricted cell surface target that is an ideal immunotherapeutic target. CLEC2A is highly expressed in KMT2A-r AML, entirely absent in normal hematopoietic cells, directly and causally linked to the KMT2A fusion, and can be used for target-directed cytotoxicity.

At a subset of MYB-bound enhancers, the continued presence of MYB is absolutely required to maintain enhancer activity and oncogene upregulation. Further exploration of associated co-factors that mediate MYB-dependent enhancer activity may identify novel targets for therapeutic exploitation.

The IPSS-M is undoubtedly an improvement in MDS risk prediction, however our real-world data collected over a period of six months show that 7% of patients (12/171) will not be assigned to a distinct risk category. To reduce this proportion, a solution for dealing with genetic VUS has to be provided.

In this study, a human induced pluripotent stem cell (hiPSC) line harboring KMT2A-AFF1 (IMSUTi002-A-2), which has the ability to simultaneously induce the doxycycline-inducible expression of KMT2A-AFF1 and EGFP, was established. This hiPSC can be a powerful model for understanding infant leukemia and risk assessment of leukemogenesis.

Finally, the over-expression of KMT2A partially reversed the inhibitory effects of up-regulation of miR-361-3p. A potential therapeutic candidate target for the treatment of AML may be miR-361-3p/KMT2A.

Upon engraftment, treatment was started with either chemotherapy (cytarabine for 5 days+doxorubicin for 3 days), the FLT3 inhibitor AC220, chemotherapy followed by AC220, or AC220+Trametinib, a MEK inhibitor. The specific treatment given affected survival and impacted the evolution of genetically distinct cells. The general lack of acquired mutations upon targeted treatment suggests that target-independent mechanisms that result in alternate activation of survival/proliferation explains acquired resistance in a majority of mice. flt3 inhibitor, AML, KMT2A

To date at least six different menin-MLL inhibitors are undergoing clinical evaluation as first- and second-line monotherapy in acute leukaemias: DS-1594, BMF-219, JNJ-75276617, DSP-5336, revumenib, and ziftomenib, however, only for revumenib and ziftomenib early clinical data have been reported. The clinical development of novel menin-MLL inhibitors is well in line with the currently ongoing paradigm shift towards targeted therapies seen in the AML treatment landscape. Moreover, the clinical assessment of combinations of these inhibitors with established therapy options in AML could be the fuel for an improved outcome of MLL/NPM1 patients.

Second, murine Srsf2P95H leukemias showed improved prolonged survival when treated with olaparib (PARPi) compared to vehicle treatment in vivo...In summary, our data establish a previously unknown link between R-loop-induced PARP1 response and RNA splicing perturbation and provide a mechanistic rationale to evaluate the clinical efficacy of PARP inhibitors in spliceosome-mutant malignancies. Furthermore, our study highlights a new therapeutic potential of targeting the R-loop tolerance pathways caused by different spliceosome gene mutations.

Additionally, co-treatment with FHD-286 and venetoclax, decitabine or OTX015, as compared to each drug alone or vehicle control, significantly reduced AML burden and improved the overall survival of the NSG mice, without inducing significant toxicity. Taken together, these findings highlight the promise of FHD-286 treatment alone and in rational combinations in exerting significant anti-AML efficacy against cellular models of AML, especially those with MLL-r, mtNPM1 or chromosome 3q26 lesions and EVI1 overexpression.

In conclusion, we report on a high throughput drug screen in primary pediatric leukemia specimens whose results translate into clinically meaningful responses. This innovative treatment approach is now being evaluated in a multi-institutional upfront trial for infants with newly diagnosed ALL.

Functionally, overexpression of MYBBP1A phenocopies the tumor-suppressor effects of LIN28B, while its perturbation omits it. Thereby, we propose that developmentally restricted expression of LIN28B provides a layer of protection against MYB-dependent AML.

Single-cell characterization of the AZD1775 response in a MLL-r patient-derived xenograft (PDX) model supported the in vivo relevance of this drug resistance mechanism. Informed by the genomic profiles, sequential administration of AZD1775 with inhibitors of pre-BCR signaling or fatty acid synthesis was designed to target the resistant cell state and this approach effectively prevented cell survival and recovery of ALL cells.Collectively, our findings provide new insights into the tight connectivity of gene regulatory programs associated with cell survival and cell fate regulation in response to drugs targeting cell cycle regulation and provide a rationale for combination therapies with low toxicity drugs such as dasatinib or fatostatin to counteract drug resistance that occurs through cell state switching.

Based on these observations, and clinical efficacy of the combination of venetoclax and decitabine/azacitidine, we determined the in vitro lethal activity of co-treatment with FHD-286 and venetoclax or decitabine against AML cell lines and PD AML cells. Additionally, co-treatment with FHD-286 and venetoclax or decitabine or OTX015, as compared to each drug alone or vehicle control, significantly reduced the AML burden and improved median and overall survival of the immune-depleted mice, without inducing significant toxicity. Taken together, these findings highlight the promise of FHD-286 treatment alone and in rational combinations in exerting significant anti-AML efficacy against cellular models of AML, especially those with MLL-r, mtNPM1 or chromosome 3q26 lesions and EVI1 overexpression.