Approach For Acute Myeloid Leukemia Research Articles

Precision Medicine Approaches in Acute Myeloid Leukemia with Adverse Genetics.

The treatment of acute myeloid leukemia (AML) with adverse genetics remains unsatisfactory, with very low response rates to standard chemotherapy and shorter durations of remission commonly observed in these patients. The complex biology of AML with adverse genetics is continuously evolving. Herein, we discuss recent advances in the field focusing on the contribution of molecular drivers of leukemia biogenesis and evolution and on the alterations of the immune system that can be exploited with immune-based therapeutic strategies. We focus on the biological rationales for combining targeted therapy and immunotherapy, which are currently being investigated in ongoing trials, and could hopefully ameliorate the poor outcomes of patients affected by AML with adverse genetics.

FLT3 and IDH1/2 Inhibitors for Acute Myeloid Leukemia: Focused Clinical Narrative Review of Forthcoming Drugs from an Indian Context

AbstractTherapeutic approaches for acute myeloid leukemia (AML) have witnessed minimal evolution in recent decades, primarily relying on advancements in supportive care and transplantation to drive improvements in overall survival rates. However, treatment with intensive chemotherapy may not be feasible for patients with advanced age or reduced fitness, and outcomes for patients with relapsed/refractory disease continue to be suboptimal. Several agents with a novel mechanism of action have been developed in the past decade and have shown efficacy in patients with both newly diagnosed and relapsed AML. Out of these, several FLT3 (FMS like tyrosine kinase 3) and IDH1/2 (isocitrate dehydrogenase 1/2) inhibitors have received regulatory approval in specific clinical settings and are available for clinical use. This is an actively expanding field with several ongoing clinical trials in advanced phases. We provide a focused narrative review of drugs from these two categories with available clinical data.

Single-Cell Proteomic Analysis Reveals Menin Inhibition-Induced Proteomic Alterations in AML Patients Treated with Revumenib

Menin inhibition is a promising therapeutic approach for acute myeloid leukemia (AML) with certain genetic alterations including KMT2A rearrangements or NPM1 mutations. The first-in-human Phase 1 clinical trial of revumenib (SNDX-5613) in patients with R/R AML showed promising results and induced complete remission in patients who refractory to multiple lines to therapy. These findings suggest that revumenib could provide a new therapeutic option for patients with AML with KMT2A and NPM1 genetic alterations. AML is characterized by the existence of distinct differentiation hierarchies, a phenomenon substantially contributing to disease heterogeneity. AML hierarchies exhibit distinct expressions of phenotypic profiles, apoptotic networks, signaling pathways, and metabolic profiles, leading to varying sensitivity towards targeted therapies, resulting in differential sensitivity to targeted therapies. Revumenib induces AML differentiation and thus shift the balance between AML hierarchies, resulting in drastic alterations in the overall AML proteomic profiles and enrichment of distinct leukemia phenotypes with differential sensitivity to targeted therapies. Detailed interrogation of revumenib-induced proteomic alterations could permit precise targeting of persistent cells and development of data-driven combinatorial approaches to achieve higher response rates. Moreover, the distinct combinations of genetic alterations can impact the efficacy of revumenib-induced differentiation and therapeutic outcomes. Thus, to better understand these complexities we performed multimodal single-cell (sc) analysis of AML landscape in R/R AML treated with revumenib (n=4) in Phase 1. We utilized two leukemia-focused 51-parameter CyTOF panels to analyze pre and post-treatment samples from R/R AML patients treated with revumenib. Sc proteogenomic profiling was performed using MissionBio platform using a panel covering 37 genes with recurrent AML-relevant mutations. UMAP and clustering analyses of CyTOF data identified AML blasts, unveiled quantitative changes in cell composition, and delineated proteomic shifts induced under revumenib therapy pressure. We observed enrichment of CD11b+/-CD68+, more differentiated monocytic cells situated at close proximity to AML blasts and depletion of immature AML blasts. Through unsupervised analysis, we discovered discrete AML differentiation hierarchies, delineated by a differentiation continuum that initiates with immature AML blasts (CD34+/-c-Kit+/-), progresses through intermediate AML blasts (CD68+/CD11b-/CD14-), and culminates with more differentiated monocytic cells (CD68++/CD11b+/CD14+/-). Notably, intermediate AML blasts and monocytic cells were enriched in post-treatment samples. Simultaneous ScDNA+protein analysis showed enrichment of differentiated AML blasts with monocytic/dendritic cell phenotype and harboring AML mutations. Differentiated AML blasts expressed higher levels of MCL1 and BCL-xL and upon differentiation we observed gradual downregulation of BCL2. Importantly, intermediate and more differentiated AML blasts under revumenib therapy expressed high levels of p53 protein, a feature that can partly attributed to NPM1 mutations. Sc proteomic analysis delineated proteomic shifts elicited by revumenib and identified potential therapeutic partners, by targeting MCL1, BCL-xL and MDM2, that could be used in combination with revumenib to improve therapeutic efficacy. We next performed differential expression analysis by comparing the proteomic profiles of pre- and post-therapy samples. We observed suppression of less differentiated AML phenotypic profiles (c-Kit, CD123, CD34) along with MEIS1 and PBX3. Importantly, we also observed significant alterations in immune landscape, suggesting that revumenib could rewire Myeloid-to-T and NK cell interaction/communication by inducing proteomic shifts and driving AML blast differentiation. Further analysis of an expanded cohort of R/R AML patients is currently underway. In conclusion, multimodal sc analysis revealed profound proteomic alterations induced by revumenib and identified potential therapeutic targets. These findings present new avenues for optimizing combinatorial treatment regimens, enhancing revumenib's efficacy, and illuminating survival mechanisms in persistent, differentiated AML blasts.

Recent Advancements in Acute Myeloid Leukemia Have Led to Incremental Improvement in Overall Survival

Background: Treatment approaches in acute myeloid leukemia are rapidly evolving due to a dynamic treatment landscape, routine molecular profiling, and the detection of measurable residual disease. Recently, there has been a surge in FDA approvals for novel therapies (e.g., midostaurin, gilteritinib, CPX-351, enasidenib, ivosidenib, and venetoclax), as well as a departure from a “one-size-fits-all” treatment approach. It is unclear, however, what effect these changes have had on overall survival over time. Since 2017, we have witnessed a significant introduction of novel therapeutics. We hypothesized that patients diagnosed after 2017 may have improved survival due to recent therapeutic advances. Methods: We retrospectively analyzed 627 consecutive patients in the Project ERIS database aged > 18 years with AML treated at VCU Massey Comprehensive Cancer Center from 2015 to 2022. We limited the analysis to January 1, 2015 to December 31, 2019 to avoid confounding from the COVID-19 pandemic. We obtained cytogenetic and molecular characteristics, induction regimens, allogeneic stem cell transplant status, and survival data. The median overall survival (mOS) was compared across calendar years using the Kaplan-Meier method. Categorical variables were analyzed using Fisher's exact test. Results: The median age at AML diagnosis was 62.9 years (range, 19.6-93.0), and the median ECOG performance status was 1 (range, 0-4). The median Charlson Comorbidity Index score was 5 (range, 0-14). There were 139 (22.2%) patients with ELN 2022 favorable-risk disease, 199 (31.7%) with intermediate risk, and 260 (41.5%) with adverse risk. The median OS of all patients diagnosed with AML in 2015 was 8.8 months. In 2016, the mOS was 14.5 months. There was a statistically significant improvement in mOS in 2016 compared to 2015 (HR 0.62 [95% CI 0.40-0.95], p = 0.027). The mOS in 2017, 2018, and 2019 was 12.9 months, 11.1 months, and 19.7 months, respectively. A significant improvement in OS was noted between 2015 and 2019 (HR 0.55 [95% CI 0.36-0.85], p = 0.003) in the entire cohort (Figure 1). When stratified by ELN 2022 genetic risk, clinically relevant improvement in OS was noted across all risk categories from 2015 to 2019, which reached statistical significance in the adverse risk group - favorable risk mOS: 16.4 months vs not reached (p = 0.141); intermediate risk: 13 months vs 18.7 months (p = 0.064); adverse risk: 7.2 months vs 13 months (p = 0.02). We observed expected changes in front-line treatment in this timeframe with decreased single-agent hypomethylating agent (HMA) usage in favor of HMA + venetoclax and increased intensive induction therapies outside of 7+3 (Figure 2). Strikingly, increased procession to allogeneic stem cell transplantation (HCT) was noted in the same timeframe (18.9% in 2015 vs 35.1% in 2019, p = 0.049). Conclusions : Our data demonstrate an emerging trend of clinically significant improvement in overall survival in patients with AML. The introduction of a multitude of therapeutic options may be associated with significantly improved survival over time. In addition to the advent of novel therapeutics leading to improved outcomes, the refinement of SCT conditioning regimens has likely led to the improved accessibility of HCT. In summary, we present an encouraging and significant trend of improved survival and access to HCT, particularly for patients with adverse-risk disease.

Venetoclax Combined with Hag Regimen in Newly Diagnosed ETP-ALL: Interim Analysis of a Prospective, Multicenter, Phase 2 Trial

Background: Early T-cell precursor (ETP) acute lymphoblastic leukemia (ALL) is identified as a subset of T-lineage ALL with a unique immunophenotype and genome profile in 2009. Patients with ETP-ALL have a relatively poor outcome with standard chemotherapy and studies showed that therapies utilized for myeloid neoplasms may be effective in ETP-ALL given the relatively high frequency of molecular myeloid features. In recent years, targeting of the antiapoptotic protein BCL-2 has emerged as an effective approach in acute myeloid leukemia (AML). Preclinical studies reported that ETP-ALL cells also express high level of BCL-2 and are sensitive to the BCL-2 inhibitor venetoclax (VEN). However, the clinical efficacy of venetoclax combination therapies in ETP-ALL patients is still limited. Our data showed that homoharringtonine (HHT) showed strong synergistic effect with VEN in ETP-ALL (2022 ASH abstract #170604). We therefore conducted a study of combination of VEN and HHT-based HAG regimen (V-HAG regimen) in newly diagnosed ETP-ALL patients. The aim of this study was to investigate the activity and tolerability of V-HAG regimen for newly diagnosed ETP-ALL. Methods: In this prospective, multicenter, phase 2 clinical trial conducted in 7 different hematological centers in China, eligible patients were newly diagnosed ETP-ALL(aged≥16 years old) based on the 2016 WHO classification with an Eastern Cooperative Oncology Group performance status of 0-2. Patients received venetoclax (100mg on day1, 200mg on day 2 and 400mg on day 3-14, if the blast cells in bone marrow was more than 5% on day 14, the patient continued to receive venetoclax 400mg until day 28), homoharringtonine (1.4 mg/m 2,2mg maximum daily, intravenously daily from on d1-10), Low-dose cytarabine (10 mg/m2 subcutaneously every 12h on d1-14), and G-CSF (100ug/m 2 daily on d1-14). Venetoclax dose was reduced by at least 50% in the patients receiving concomitant moderate or strong CYP3A4 inhibitors (such as azole antifungals et al). The primary endpoint was the rate of composite complete remission (CRc) after one cycle of induction treatment, including CR and CR with incomplete count recovery (CRi). Secondary endpoints included bone marrow (BM) minimal residual disease (MRD) by flow cytometry after one cycle of induction treatment, overall survival (OS), event-free survival (EFS), and adverse events (AEs). Here, we report results of the interim analysis. Results: Between July 2022 and July 2023, we enrolled 18 patients with newly diagnosed ETP-ALL in 7 different hematological centers. 14 of 18 patients (77.8%) were male and 22.2% were female, with a median age of 51 years (range, 29 to 73 years). As of July 31, 2023, 15 patients were available for the assessment of treatment results. Among the 15 patients, 14 patients were given standard V-HAG regimen as showed above and one 73-year-old patient, who had interstitial pneumonia at the onset of ETP-ALL, was given dose-reduced V-HAG regimen. To our surprise, after the first cycle of treatment with V-HAG, all the 15 patients achieved CRc (100% CRc rate), including the 73-year-old patient with dose-reduced regimen. Then, after one to three cycles of consolidation treatment with V-HAG regimen, 7 of 15 patients have proceeded to allo-HSCT so far. With a median follow-up of 7.7 months, both the median OS and EFS were not achieved. In fact, to date, except for the 73-year-old patient who eventually relapsed (6% blasts in BM after receiving a second cycle of dose-reduced V-HAG regimen as consolidation) and died of respiratory failure, all the other 14 patients are remaining alive and event-free. For the adverse events, the most common toxicities were grade 4 neutropenia (93.33%), grade 4 thrombocytopenia (73.33%) and grade 3 febrile neutropenia (26.67%). No early death occurred. Conclusions: Venetoclax Combined with HAG regimen achieved an 100% CRc rate in newly diagnosed ETP-ALL to date. Enrollment is ongoing to assess its efficacy and safety in treating newly diagnosed ETP-ALL. This therapy is a promising and well-tolerated regimen in newly diagnosed ETP-ALL patients. Trial registration: The trial was registered in the Chinese Clinical Trial Register with the registration number ChiCTR2200061708.

HGF Regulation in the Tumor-Supportive Microenvironment Combined with Pan-PIM Kinases Inhibition in Malignant Cells As a Multi-Target Approach for Acute Myeloid Leukemia

Background: In acute myeloid leukemia (AML), persistent clonal proliferation of malignant myeloid cells results in high severity and low cure potential. Resistance to currently available chemotherapeutics and disease relapse remains an important concern worldwide. Several molecular targets play key roles in impairing therapeutic response, including PIM-kinases, a serine/threonine kinase family associated with the progression of hepatocyte growth factor (HGF)-driven cancers through its receptor, MET. We reported that enhanced HGF secretion by bone marrow (BM) mesenchymal stromal cells (MSC) correlated with low levels of the serine protease inhibitor kunitz-type2 (SPINT2) in AML (Roversi et al., 2019), which are affected by immunosuppressive properties of the tumor microenvironment (TME). However, the interplay between SPINT2, HGF, and PIM-kinases in the TME is yet to be elucidated and could represent an important multi-target therapeutic strategy in hematological cancers. Aims: Given the importance of HGF to AML prognosis and progression, we analyzed the interplay between SPINT2, HGF, and pan-PIM kinases by evaluating the gene expression and the effects of a novel pan-PIM kinase inhibitor, PIM447 (Novartis), in leukemia cells and in the TME. Methods: SPINT2, HGF, PIM1, PIM2 and PIM3 mRNA expression data were obtained from OHSU (2018) AML study and TCGA (cBio Portal). Correlation analysis was obtained by Spearman's coefficient (r). A total of 5 healthy donors (HD) and 5 de novo AML patients BMMSC (CD90+CD105+CD73+CD45-CD34-CD31-HLA-DR-) were treated with 5-Azacitidine (Aza), and evaluated for SPINT2 gene expressions. Myeloid (OCI-AML3, MOLM13, U937) and lymphoblastic (RS4;11, Jurkat) leukemia cells were treated with increasing concentrations of PIM447, and the 101nd apoptosis rates were determined. Peripheral blood and BM mononuclear cells (PBMC/BMMC) from HD were tested for cytotoxicity. Leukemia cells were also examined for reactive oxygen species (ROS), nitric oxide (NO) production, and mitochondrial membrane potential (ΔΨm). To verify PIM447 action onto an immunosuppressive TME, cocultures of leukemia cells and monocytes or monocyte-derived macrophages (MDMs) were performed. To understand the interplay between SPINT2 and PIM-kinases, cocultures of SPINT2-overexpressed MSC and leukemia cells, were performed. Statistical analyzes were performed using Kruskal Wallis, ANOVA or Mann-Whitney tests ( P<.05). Results: The analysis of gene expression performed in MC from 188 AML patients (age median: 57.5 years [range: 18-88]) showed that levels of HGF correlated positively with PIM1, PIM2, and PIM3 ((r) =.8727;.9094;.9093, respectively, P<.0001) and negatively with SPINT2 (r=-.06402). We also verified that SPINT2 mRNA expression was upregulated in AML-BMMSC ( P<.05) after Aza treatment when compared to HD-BMMSC, suggesting that this gene is methylated in AML. Our in vitro results showed PIM447 treatment (2-20μM) yielded reduced cell viability and increased apoptosis in leukemia cells [IC50 range: 12.2-22.2μM, P<.01] without affecting HD cells. PIM447 reduced ROS, NO production, and ΔΨm (all P<.0001) in all cell lines. PIM447 treatment of macrophages differentiated from HD-PBMC revealed a shorter population of M2 macrophages (HLA-DR-CD206+) ( P<.001) and an increased population of M1 macrophages (HLA-DR+CD80+) ( P<.05). Moreover, PIM447 promoted apoptosis of leukemia cells co-cultured with MDMs ( P<.0001). Interestingly, co-culture analyses of SPINT2-overexpressed MSC enhanced PIM447 cytotoxic activity towards leukemia cells (P<.05) and reduced cell-cell adhesion by diminishing CD49b, CD49d, and CD49e (P<.05), suggesting an interplay between SPINT2 and pan-PIM kinases Conclusion: Collectively, our data identify a novel pan-PIM kinase inhibitor, PIM447, which effectively induces leukemia cell apoptosis through reducing MET receptor activation as well as acts on their tumor-supportive microenvironment by inducing a phenotypic shift from immunosuppressive M2 to anti-tumor M1 macrophages. PIM447 also interplays with SPINT2/HGF pathway in the TME, reducing AML progression. These findings suggest that a pivotal strategy to treat AML could be a multi-target therapy, acting both on leukemia cells and in the tumor microenvironment. Funding: FAPESP #2017/21801-2, #2019/25247-5, #2021/05320-0; CNPq #303405/2018-0.

ASXL1 mutations are associated with a response to alvocidib and 5-azacytidine combination in myelodysplastic neoplasms.

Inhibitors of anti-apoptotic BCL-2 family proteins in combination with chemotherapy and hypomethylating agents (HMAs) are promising therapeutic approaches in acute myeloid leukemia (AML) and high-risk myelodysplastic syndromes (MDS). Alvocidib, a cyclin-dependent kinase 9 (CDK9) inhibitor and indirect transcriptional repressor of the anti-apoptotic factor MCL-1, has previously shown clinical activity in AML. Availability of biomarkers for response to the alvocidib + 5- AZA could also extend the rationale of this treatment concept to high-risk MDS. In this study, we performed a comprehensive in vitro assessment of alvocidib and 5-AZA effects in n=45 high-risk MDS patients. Our data revealed additive cytotoxic effects of the combination treatment. Mutational profiling of MDS samples identified ASXL1 mutations as predictors of response. Further, increased response rates were associated with higher gene-expression of the pro-apoptotic factor NOXA in ASXL1 mutated samples. The higher sensitivity of ASXL1 mutant cells to the combination treatment was confirmed in vivo in ASXL1Y588X transgenic mice. Overall, our study demonstrated augmented activity for the alvocidib + 5-AZA combination in higher-risk MDS and identified ASXL1 mutations as a biomarker of response for potential stratification studies.

Natural Cycloartane Triterpenoids from Corypha utan Lamk. with Anticancer Activity towards P388 Cell Lines and their Predicted Interaction with FLT3.

Cancer is the second leading cause of death in the world. Leukemia is a type of cancer that accounts for 31.5% of all cancers in children under the age of 15 in industrialized countries and 15.7% in developing countries. The inhibition of FMS-like tyrosine kinase 3 (FLT3) is a suitable approach for acute myeloid leukemia (AML) therapy as it is overexpressed in AML. This study intends to explore the natural constituents from the bark of Corypha utan Lamk., and assess their cytotoxicity on murine leukemia cell lines (P388) in addition to predicting their interaction with FLT3 as a studied target by computational methods. Compounds 1 and 2 were isolated from Corypha utan Lamk using the stepwise radial chromatography method. These compounds were assessed for their cytotoxicity against Artemia salina using the BSLT and P388 cells and the MTT assay. The docking simulation was employed to predict the possible interaction between triterpenoid and FLT3. Isolation from the bark of C. utan Lamk. generated two triterpenoids, cycloartanol (1) and cycloartanone (2). Based on the in vitro and in silico studies, both compounds were found to have anticancer activity. The evaluation of cytotoxicity from this study reveals that cycloartanol (1) and cycloartanone (2) could inhibit P388 cell growth (IC50 value at 102.6 and 110.0 μg/mL, respectively). The binding energy of cycloartanone was -9.94 Kcal/mol with a Ki value of 0.051 μM, while the binding energy and Ki value of cycloartanol (1) were found to be 8.76 Kcal/mol and 0.38 μM, respectively. These compounds also demonstrate a stable interaction by forming hydrogen bonds with FLT3. Cycloartanol (1) and cycloartanone (2) exhibit potency as anticancer agents by inhibiting P388 cells in vitro and the FLT3 gene in silico.

Valosin-containing protein (VCP/p97) is prognostically unfavorable in pediatric AML, and negatively correlates with unfolded protein response proteins IRE1 and GRP78: A report from the Children's Oncology Group.

The endoplasmic reticulum (ER) is the major site of protein synthesis and folding in the cell. ER-associated degradation (ERAD) and unfolded protein response (UPR) are the main mechanisms of ER-mediated cell stress adaptation. Targeting the cell stress response is a promising therapeutic approach in acute myeloid leukemia (AML). Protein expression levels of valosin-containing protein (VCP), a chief element of ERAD, were measured in peripheral blood samples from in 483 pediatric AML patients using reverse phase protein array methodology. Patients participated in the Children's Oncology Group AAML1031 phase 3 clinical trial that randomized patients to standard chemotherapy (cytarabine (Ara-C), daunorubicin, and etoposide [ADE]) versus ADE plus bortezomib (ADE+BTZ). Low-VCP expression was significantly associated with favorable 5-year overall survival (OS) rate compared to middle-high-VCP expression (81%versus 63%, p<0.001), independent of additional bortezomib treatment. Multivariable Cox regression analysis identified VCP as independent predictor of clinical outcome. UPR proteins IRE1 and GRP78 had significant negative correlation with VCP. Five-year OS in patients characterized by low-VCP, moderately high-IRE1 and high-GRP78 improved after treatment with ADE+BTZ versus ADE (66%versus 88%, p=0.026). Our findings suggest the potential of the protein VCP as biomarker in prognostication prediction in pediatric AML.

Hexamethylene Amiloride Sensitizes AML to Venetoclax through Inducing Lysosomal Membrane Permeabilization

Chemotherapy remains the standard therapeutic approach for acute myeloid leukemia (AML). Although several new drugs have received approval for clinical usage, including the selective BCL2 inhibitor venetoclax, refractory disease or resistance continues to be a recurring theme, and exploring more effective therapies for AML treatment remains necessary. Intracellular pH dynamics are vital determinants for cancer progression and chemoresistance. Tumors maintain a more alkaline intracellular pH (pHi) dependent on proton exporters, including sodium-hydrogen exchangers (NHEs). Elevated NHE1 expression has emerged as a biomarker for the tumorigenesis and prognosis of solid tumors. However, whether targeting NHE1 with inhibitors could inhibit AML cell growth and the underlying mechanisms remain unknown. We found that NHE1 was highly expressed in AML and predicted a worse prognosis based on data analysis of public database. Moreover, NHE1 knockdown inhibited the growth of AML cells. In addition, NHE1 inhibitor Hexamethylene amiloride (HA) significantly inhibited proliferation and promoted apoptosis in a concentration-dependent manner in both AML cell lines and primary AML cells. Next, we combined HA with several first-line or novel drugs and found that HA combined with venetoclax significantly inhibited viability of AML cells. AML patients with higher NHE1 expression were less sensitive to BCL-2 inhibitors. This suggested that HA and venetoclax might be an effective combination to treat AML. As expected, HA synergized with venetoclax to inhibit proliferation and promote apoptosis. In vivo potential of HA combined with venetoclax was evaluated in a MV4-11-derived xenograft mouse model (Fig.1). The combinational regimen prolonged survival and alleviated leukemia burden in bone marrow, spleen and peripheral blood. We further validated the effect of HA with venetoclax with primary AML cells. Consistent with results in cell lines, HA combined with venetoclax also exerted synergistic effect in inhibiting viability and promoting apoptosis. RNA-Seq analysis revealed that lysosome pathway was significantly enriched in the combination group. We further verified the increased quantity of lysosome, and the swelling and rupture of lysosome with TEM (Fig.2). Moreover, HA combined with venetoclax induced obvious LGALS3 puncta formation in this cell line, which represented the occurrence of lysosomal membrane permeabilization (LMP), leading to the release of proteases which eventually results in cell death. In conclusion, our results for the first time provide evidence that the NHE1 inhibitor HA or its combination with venetoclax efficiently inhibits the growth of AML in vitro and in vivo. This study might shed light on the clinical treatment of AML involving proton exporter inhibitors with venetoclax as combinatory regime. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

ASXL1 Mutations Are Associated with a Response to the Combination of Alvocidib and 5-Azacytidine in Higher-Risk Myelodysplastic Syndromes

Introduction: Inhibitors of anti-apoptotic BCL-2 family proteins in combination with chemotherapy and hypomethylating agents (HMAs) are perspective therapeutic approaches in acute myeloid leukemia (AML) and higher-risk myelodysplastic syndromes (MDS). Inhibitors of BCL-2 family proteins previously showed potent activity against AML and higher-risk MDS. Alvocidib (Alv), a cyclin-dependent kinase 9 inhibitor and indirect transcriptional repressor of the anti-apoptotic BCL-2 family member MCL-1, has previously shown clinical activity in AML (Lee DJ et al, Expert Opin Investig Drugs 2019; Zeidner JF et al, Leuk Res 2015). A phase 1b/2 study with Alv and HMAs 5-Azacytidine (5-AZA) or decitabine in higher-risk MDS patients was recently completed (NCT03593915). However, biomarkers of response to 5-AZA + Alv combination are insufficiently characterized. In order to possibly identify biomarkers of response, we performed a comprehensive in vitro assessment of Alv and 5-AZA effects in a cohort of n=45 higher-risk MDS patients. Methods: CD34+ hematopoietic stem and progenitor cells (HSPCs) were isolated from bone marrow (BM) aspirates using positive selection with MACS microbeads. CD34+ cells of aged-matched healthy controls (HC, n=11) were obtained from bone specimen after femur endoprosthesis surgery. HSPCs were expanded for four days in StemSpan SFEM II medium containing StemSpan Myeloid Expansion Supplement (Stem Cell Technologies) and treated with 5-AZA for 48h, Alv for 24h or their sequential combination (5-AZA for 48h followed by Alv for 24h). Cell viability was determined using CellTiter-Glo (CTG) and Annexin-V apoptosis assays. MCL-1 dependency of primary MDS HSPCs was assessed using NOXA-derived T-MS1 peptide. MDS recurrent mutations in BM mononuclear cells were assessed using myeloid NGS panel deep sequencing containing 67 genes. For in vivo tumor transfer experiments, splenic cells from CD45.2+Asxl1Y588X transgenic (Tg) mice were injected intravenously into sublethally irradiated CD45.1+ recipients through tail veins. Engrafted mice were treated with 1 mg/kg 5-AZA intraperitoneally (i.p.) on days 1-3 (qdx) every other week. Alv was administered i.p. at a dose of 2.5 mg/kg on day 5 (qw) in the weeks when 5-AZA was applied. Mice were sacrificed 11 weeks after the transplantation and the percentage of CD45.2+ cells in the BM was assessed using flow cytometric analysis. Results: The combination of 5-AZA+Alv showed an additive cytotoxic effect on MDS cells in CTG cell viability assays (median cell viability was 74%, 74% and 55% for 5-AZA, Alv and combination, respectively, p<0.0001). In annexin-V apoptotic assays, MDS cells were more sensitive to the cytotoxic effect of the combination treatment compared to HC (median percent of apoptotic and dead cells was 37% for MDS vs 26% for HC, p=0.0256). In analogy to in vitro studies, accelerated clearance of xenografted MDS-L cells from the peripheral blood of NSGS mice was observed after 5-AZA+Alv treatment compared to single agents. MCL-1 dependency of primary MDS samples did not significantly correlate with cytotoxic effects of Alv and combination treatment. However, the presence of ASXL1 mutations was significantly associated with higher cytotoxic activity of 5-AZA+Alv combination in univariable (p=0.0044) and multivariable (p=0.042) analyses. Increased sensitivity of BM cells to the cytotoxic effects of 5-AZA+Alv was also observed in Asxl1Y588XTg mice. The combination treatment facilitated clearance of CD45.2+Asxl1Y588X mutant leukemic cells from CD45.1+ recipients compared to 5-AZA monotherapy (p=0.0156). Histological analysis of BM cells after 5-AZA+Alv treatment in CD45.1+ recipients showed decrease in the percentage of immature blasts and improved development of mature BM cells when compared to 5-AZA monotherapy (p=0.0391). Improved cytotoxic effects of Alv and 5-AZA+Alv in ASXL1 mutant compared to ASXL1 wild type MDS samples were associated with higher expression of pro-apoptotic MCL-1 antagonist NOXA (p=0.0017). Conclusions: We provided a pre-clinical rationale for the use of the 5-AZA+Alv combination for higher risks MDS and proposed ASXL1 mutations as potential genetic biomarkers of response in prospective clinical trials.

Diagnostic Approach for Acute Myeloid Leukemia Based on the World Health Organization Classification of Hematologic Neoplasms

Acute myeloid leukemias (AMLs) are heterogeneous hematologic neoplasms characterized by myeloblast or promyelocyte proliferation without normal differentiation. The World Health Organization (WHO) classifies AMLs on the basis of chromosomal and genetic aberrations, with different prognoses for each subtype. Therefore, accurate diagnosis and classification of AMLs is critical for timely and appropriate treatment. Initial diagnostic workup includes morphologic assessment of the bone marrow aspirate and trephine biopsies, immunophenotyping using flow cytometry or immunohistochemistry stains, chromosomal analysis using the G-banding technique or fluorescence in situ hybridization, and mutation analysis using polymerase chain reaction, direct sequencing, or next-generation sequencing. The present study provides an algorithm for AML diagnosis and classification based on the WHO criteria and describes different clinicopathological stages of the workup.

Anticancer Effects of ZnO/CNT@Fe3O4 in AML-Derived KG1 Cells: Shedding Light on Promising Potential of Metal Nanoparticles in Acute Leukemia.

Background: Therapeutic approaches for acute myeloid leukemia (AML) have remained largely unchanged for over 40 years and cytarabine and an anthracycline (e.g., daunorubicin) backbone is the main induction therapy for these patients. Resistance to chemotherapy is the major clinical challenge and contributes to short-term survival with a high rate of disease recurrence. Given the established efficacy of nanoparticles in cancer treatment, this study was designed to evaluate the anticancer property of our novel nanocomposite in the AML-derived KG1 cells. Materials and Methods: To assess the anti-leukemic effects of our nanocomposite on AML cells, we used MTT and trypan blue assays. Flow cytometric analysis and q-RT-PCR were also applied to evaluate the impact of nanocomposite on cell cycle and apoptosis. Results: Our results outlined that ZnO/CNT@Fe3O4 decreased viability and metabolic activity of KG1 cells through induction of G1 arrest by increasing the expression of p21 and p27 cyclin-dependent kinase inhibitors and decreasing c-Myc transcription. Moreover, ZnO/CNT@Fe3O4 markedly elevated the percentage of apoptotic cells which was coupled with a significant alteration of Bax and Bcl-2 expressions. Synergistic experiments showed that ZnO/CNT@Fe3O4 enhances the cytotoxic effects of Vincristine on KG1 cells. Conclusion: In conclusion, this study sheds light on the potent anti-leukemic effects of ZnO/CNT@Fe3O4 and provides evidence for the application of this agent in the treatment of acute myeloid leukemia.

Treatment by PI3K/mTOR Inhibitor BEZ235 Combined with TLR-7/8 Agonist Interfere with Immune Evasion Mechanisms of WEHI-3 Mouse Leukemia Cells.

Several PI3K/Akt/mTOR pathway inhibitors and TLR agonists induce tumor cell death. However, the mechanisms of these therapeutic approaches in acute myeloid leukemia (AML) cells are still unknown. To investigate the effects of BEZ235, as a dual inhibitor of PI3K and mTOR pathways, and TLR7/8 agonist R848 on the expression and regulation of the immune inhibitory molecules in myeloid leukemia cells. WEHI-3 leukemia cells were incubated with dual PI3K and mTOR inhibitor BEZ235 and TLR7/8 agonist R848 for 48 hrs. Firstly, cell viability was assessed by MTT method. The semi-quantitative relative mRNA expression of Galectin-9 (Gal-9), PD-L1, PVR, and STAT3 was assessed according to HPRT as a housekeeping gene. Finally, the protein expression of phosphorylated STAT3 was evaluated by western blotting analysis. WEHI-3 cells showed growth inhibition following treatment with BEZ235 and R848 whose combination exerted more proliferation arrest. The mRNA expression of Gal-9, PD-L1 and PVR immune checkpoint molecules significantly reduced in treated cells with BEZ235 and R848. Combined treatment indicated more reduction compared with the single treatment. Finally, the expression and phosphorylation of STAT3 were down-regulated after a single or dual treatment with BEZ235 and R848. Our results conclude that treatment with the combination of BEZ235 and R848 interferes with immune evasion mechanisms through STAT3-signaling pathway in WEHI-3 leukemia cells.

EPCR Signaling Controls the Activity of Hematopoietic Stem Cells Independent of Coagulation Regulation

BackgroundAll mature blood cells are derived from multipotent hematopoietic stem cells (HSCs) which are activated to meet the demand of the host during inflammation and injury. The endothelial cell protein C receptor (EPCR) is a marker for primitivity and quiescence of HSCs but the relative contributions of EPCR signaling versus anticoagulant functions in HSC maintenance are incompletely defined.AimsWe aimed to dissect functions of EPCR by studying anticoagulant and signaling function in HSC of EPCR C/S mice carrying a single intracellular point mutation abolishing normal trafficking of EPCR through endo-lysosomal compartments. We assessed the contributions of EPCR signaling to stem cell maintenance by analyzing HSC mobilization and leukemia progression.MethodsWe studied the frequency and cell cycle activity of bone marrow (BM) hematopoietic stem and progenitor cells (HSPC) by multicolor flow cytometry. Furthermore, we analyzed changes in hematopoiesis in steady state, after granulocyte colony stimulating factor (G-CSF)-induced mobilization, in the context of aging and in the context of leukemia, using the MLL-AF9-induced acute myeloid leukemia (AML) model.ResultsHSCs, lungs and isolated lung-derived smooth muscle cells of EPCR C/S mice showed protein expression levels and anticoagulant function indistinguishable from wildtype (WT). We found an increase of circulating HSCs in the peripheral blood of EPCR C/S mice compared to control under steady state conditions. Isolated HSC displayed diminished polarization of CDC42 and VLA-4 (α 4β 1 integrin) affinity to VCAM-1 in EPCR C/S versus strain-matched EPCR wt mice, indicating that EPCR signaling directly controls HSC retention via integrin affinity to the BM niche. In addition, we noticed a higher cell cycle activity in myeloid-restricted progenitors of EPCR C/S mice compared to control. G-CSF treatment led to increased mobilization of both BM neutrophils and HSCs into the peripheral blood of EPCR C/S mice compared to EPCR wt mice. A myeloid bias was also seen in serially transplanted aged mice, resulting in increased frequencies of myeloid-biased progenitors in the BM of EPCR C/S mice compared to control mice, accompanied by an increase of circulating neutrophils in the blood. Consistent with higher cell cycle activity of myeloid progenitors and an overall increase of myeloid-biased output in EPCR C/S mice, induction of AML by retroviral transduction of EPCR C/S BM cells with MLL-AF9-expressing retrovirus resulted in an increase of cell cycle activity of Lin - MLL-AF9 + leukemic BM blasts and a higher leukemic load in the peripheral blood of mice transplanted with MLL-AF9 + EPCR C/S BM compared to control. As a result, MLL-AF9 + EPCR C/S leukemia showed a more aggressive disease with shortened survival times compared to control. In contrast, chemotherapy of MLL-AF9 + EPCR C/S leukemia reduced leukemic load in the peripheral blood and decelerated disease progression. These data demonstrate that increased leukemia cell cycle activity conferred chemosensitivity.ConclusionWith a site-specific EPCR mutant knock-in mouse, we here demonstrate that EPCR signaling and anticoagulant function can be separated. We provide direct evidence that EPCR signaling plays a crucial role in maintaining HSC retention via VLA-4 affinity to VCAM-1, controls cell cycle activity and myeloid output in normal, stress-induced, and malignant hematopoiesis with implications for therapeutic approaches in acute myeloid leukemia. DisclosuresRuf: MeruVasimmune: Other: Ownership Interest; ARCA bioscience: Consultancy, Patents & Royalties; ICONIC Therapeutics: Consultancy.

PNC¯27 Targeting Plasma Membrane HDM2: A Potentially Novel Therapeutic Approach for Acute Myeloid Leukemia (AML)

Acute myeloid leukemia (AML) is a devastating hematopoietic malignancy. The vast majority of AML patients are immediately refractory to induction therapy or subsequently relapses following transient complete remission, due to persistence of treatment-resistant leukemia stem cells (LSC). Thus, there is a clear need to identify new targets and develop novel and effective therapeutic approaches in this population. HDM2, an E3 ubiquitin-protein ligase, binds to p53 tumor suppressor in the cytoplasm, repressing p53 transcriptional activity and facilitating its proteasomal degradation. Overexpression of HDM2 plays a key role in tumorigenesis. Recently, it has been reported that HDM2 is not only localized to the cytoplasm but can also be found highly expressed on the plasma membrane of various cancer cells (i.e., colon, breast, pancreas) but not on normal counterparts (PNAS 2010 :107(5):1918-23). PNC-27(Oncolyze, Inc.), a 32-amino acid synthetic peptide with a penetratin domain and a HDM-2-binding domain of p53, can bind with cell membrane HDM2, causing membrane pore formation, thus inducing necrosis in solid tumor cells. However, the activity of PNC-27 in AML has not been established. Using flow cytometry analysis and confocal microscopy with anti-HDM2 antibody (Santa Cruz,N-20), we showed that HDM2 was expressed on the membrane of LSC-enriched CD34+CD38- primary blast populations procured from consecutive AML patients (n=6) at levels greater than those observed on normal CD34+CD38- cells [hematopoietic stem cells (HSC)] from healthy individuals (n=12) [median fluorescence intensity (MFI) (HDM-2/IgG control) 2.5±0.6 vs 1.1±0.1; p<0.01)]. Similar results were also observed in AML cell lines (i.e., THP-1, MV4-11,MOLM-13, NOMO1).Further, we showed that exposure to PNC-27 (50-200ug/ml) for 72 hours resulted in significantly reduced viability and colony formation activity (P<0.001) in both AML cell lines and human AML CD34+ cells compared with normal CD34+ cells, in a dose- and time-dependent manner. PNC-27 antileukemia activity was significantly and directly correlated with cell membrane HDM2 expression levels (p<0.05), more HDM2 expression, higher PNC-27 efficacy. Confocal microscopy using fluorescent anti-HDM2 and anti-PNC-27 antibodies showed that PNC-27 and HDM-2 co-localized to the membrane of primary AML CD34+ blasts. Consistent with the previous studies, we also observed membrane pore formation by electron microscopy and cell necrosis by increased LDH levels rather than apoptosis(no change in Annexin V+ cell percentage and pro-apoptosis protein levels) in PNC-27 treated cells.We further evaluated the efficacy of PNC-27 in vivo . First, CD45.2 BM cells from a MLLPTD/WTFLT3ITD/ITD AML mouse model were transplanted into CD45.1 congenic recipient mice. After confirming AML development, mice were treated with PNC-27 (40mg/kg/day; n= 7) or vehicle (n=9) for two weeks. BM cells from the treated mice were transplanted into 2nd recipient mice (2×106 cells/mouse). A significantly longer survival was observed in the 2nd BM recipients from PNC-27-treated donors (n=8) compared to the 2nd BM recipients from vehicle-treated donors (n=8) (median survival: 41 days vs 32 days; p<0.01). Next, human AML cells were transplanted into NSG-SGM3 mice. Upon confirming >10% human CD45+ cell engraftment in periphery blood (PB), the mice were treated with PNC-27 (40mg/kg/day; n=10) or vehicle (n=10) for 2 weeks, and BM cells (2×106 cells/mouse) from the treated mice were transplanted into 2nd recipient mice. Significantly reduced human CD45+ engraftment in PB at 12 weeks (59.2±7.4 vs 94.6±0.94, p<0.05) and prolonged survival were observed in the 2nd BM recipients from PNC-27-treated donors (n=10) compared to the 2nd BM recipients from vehicle-treated donors (n=7). After four months follow-up, all recipients receiving BM cells from PNC-27-treated donors survived while all recipients receiving BM cells from vehicle-treated donors died (median survival was “not reached” vs 93 days, p<0.0001). Of note wild-type B6 mice treated with PNC-27 (80mg/kg) or vehicle for 2 weeks showed no difference on WBC counts and BM cell counts, suggesting no toxicity on normal hematopoiesis.In conclusion, our results suggest PNC-27 effectively targets AML LSC-enriched population by binding with cell membrane HDM2 to induce necrosis, providing a rationale for a rapid translation of this drug into the clinic. DisclosuresStein:Stemline: Consultancy; Amgen: Consultancy, Speakers Bureau.

Vaccine and Cell-based Therapeutic Approaches in Acute Myeloid Leukemia.

Over the past decade, our increased understanding of the interactions between the immune system and cancer cells has led to paradigm shifts in the clinical management of solid and hematologic malignancies. The incorporation of immune-targeted strategies into the treatment landscape of acute myeloid leukemia (AML), however, has been challenging. While this is in part due to the inability of the immune system to mount an effective tumor-specific immunogenic response against the heterogeneous nature of AML, the decreased immunogenicity of AML cells also represents a major obstacle in the effort to design effective immunotherapeutic strategies. In fact, AML cells have been shown to employ sophisticated escape mechanisms to evade elimination, such as direct immunosuppression of natural killer cells and decreased surface receptor expression leading to impaired recognition by the immune system. Yet, cellular and humoral immune reactions against tumor-associated antigens (TAA) of acute leukemia cells have been reported and the success of allogeneic stem cell transplantation and monoclonal antibodies in the treatment of AML clearly provides proof that an immunotherapeutic approach is feasible in the management of this disease. This review discusses the recent progress and persisting challenges in cellular immunotherapy for patients with AML.

Targeting Salt-Inducible Kinase 3 As a Therapeutic Approach for Acute Myeloid Leukemia

Acute myeloid leukemia (AML) remains a devastating illness, with a clear need for the development of novel anti-leukemic therapy. CRISPR-Cas9 functional genomic screens have revealed hundreds of genetic vulnerabilities in AML cells, which can be leveraged to nominate clinically actionable targets. Our previous CRISPR screens in AML cell lines identified Salt-Inducible Kinase 3 (SIK3) as an essential gene for a subset of AML cells with high expression of the oncogenic transcription factor MEF2C, such as AMLs harboring Mixed Lineage Leukemia (MLL)-fusion proteins. Mechanistically, we have shown that the maintenance of MEF2C transcriptional output requires SIK3, which phosphorylates histone deacetylase 4 (HDAC4), a repressive cofactor of MEF2C, and thus prevents HDAC4 from nuclear entry and from suppressing MEF2C activity. SIKs 1-3 are serine/threonine kinases belonging to the adenosine monophosphate-activated protein kinase (AMPK) family. The physiological function of SIKs has been investigated in the regulation of gluconeogenesis, myogenesis and osteogenesis, yet the critical role of SIK3 in AML growth is just emerging. Thus, the evaluation of its translational potential in relevant pre-clinic models, such as patient-derived-xenografts (PDXs), is necessary. To do so, we have established a novel MLL-AF9 PDX model tractable for CRISPR genome editing via lentivirally expressing Cas9 and serial transplantation in immunodeficient mice. The PDX model maintains stable Cas9 activity; knockout of SIK3 hampered leukemia growth in vivo, demonstrating the utility of this model and the functional significance of SIK3 in AML. In parallel, we tested the anti-leukemic effect of the tool compound YKL-05-099, which inhibits the SIK kinase family and has a suitable bioavailability in mice. YKL-05-099 treatment inhibited the growth of AML cell lines in vitro via inducing cell cycle arrest and apoptosis, and AML cells with high MEF2C protein expression tended to be more sensitive to YKL-05-099. YKL-05-099 was well-tolerated by mice, and after daily administration for a month, no obvious toxicities or physiological abnormalities were observed. Normal hematopoiesis was also sustained, as indicated by complete blood counts and lineage flow cytometry analysis. By contrast, a two-week treatment regimen successfully attenuated disease progression in vivo and extended animal survival in both an MLL-AF9 mouse AML and PDX models. Importantly, we have confirmed the action of the compound is via on-target inhibition of the SIK3-HDAC4-MEF2C axis. Western-blot analysis revealed that YKL-05-099 treatment led to rapid dephosphorylation and nuclear accumulation of HDAC4 in AML cells. Accordingly, similar to SIK3 knockout, ChIP-seq analysis showed that YKL-05-099 selectively reduced histone H3 lysine 27 acetylation at a small number of genomic locations, which are enriched for MEF2C occupancy sites. This finding was supported by RNA-seq analysis as well, which showed that YKL-05-099 treatment suppressed a similar transcriptional program as observed following genetic targeting of SIK3 or MEF2C. Additionally, either overexpressing a SIK3 gatekeeper mutant or deleting HDAC4 in MLL-fusion AML cells can attenuate their sensitivity to YKL-05-099. High MEF2C expression in AML is associated with poor response to conventional chemotherapy. Our findings validate SIK3 inhibition as a possible therapeutic approach in MEF2C-positive AML and provide a rationale for developing improved drug-like inhibitors of SIK3, with enhanced specificity and bioactivity, for definitive pre-clinical investigation and for future studies in patients with AML. Disclosures Lin: Leukemia &amp; Lymphoma Society: Research Funding. Tarumoto:Lauri Strauss Leukemia Foundation: Research Funding. Gray:Gatekeeper, Syros, Petra, C4, B2S and Soltego.: Equity Ownership; Novartis, Takeda, Astellas, Taiho, Janssen, Kinogen, Voronoi, Her2llc, Deerfield and Sanofi.: Equity Ownership, Research Funding. Vakoc:Boehringer-Ingelheim: Research Funding; KSQ Therapeutics: Consultancy. Stegmaier:Rigel Pharmaceuticals: Consultancy; Novartis: Research Funding.

Immunophenotypic Detection of Measurable Residual (Stem Cell) Disease Using LAIP Approach in Acute Myeloid Leukemia.

Half of the patients with acute myeloid leukemia (AML), who achieve complete remission after chemotherapy treatment, will ultimately experience a relapse. Measurable residual disease (MRD) is an important post‐treatment risk factor in AML, because it gives additional information about the depth of the remission. Within MRD, the small population of leukemic stem cells (LSCs) is thought to be at the base of the actual relapse. In this protocol, the flow cytometric detection of MRD and LSCs herein is outlined. We give a detailed overview of the sampling procedures for optimal multiparameter flow cytometry assessment of both MRD and LSC, using leukemia associated immunophenotypes (LAIPs) and LSC markers. Moreover, an overview of the gating strategies to detect LAIPs and LSC markers is provided. This protocol serves as guidance for flow cytometric detection of measurable residual (stem cell) disease necessary for proper therapeutic decision making in AML patients. © 2019 The Authors. Basic Protocol 1: Immunophenotypic LAIP detection for measurable residual disease monitoring Basic Protocol 2: Immunophenotypic detection of CD34+CD38− leukemic stem cells

Targeting cell membrane HDM2: A novel therapeutic approach for acute myeloid leukemia.

The E3 ligase human double minute 2 (HDM2) regulates the activity of the tumor suppressor protein p53. A p53-independent HDM2 expression has been reported on the membrane of cancer cells but not on that of normal cells. Herein, we first showed that membrane HDM2 (mHDM2) is exclusively expressed on human and mouse AML blasts, including leukemia stem cell (LSC)-enriched subpopulations, but not on normal hematopoietic stem cells (HSCs). Higher mHDM2 levels in AML blasts were associated with leukemia-initiating capacity, quiescence, and chemoresistance. We also showed that a synthetic peptide PNC-27 binds to mHDM2 and enhances the interaction of mHDM2 and E-cadherin on the cell membrane; in turn, E-cadherin ubiquitination and degradation lead to membrane damage and cell death of AML blasts by necrobiosis. PNC-27 treatment in vivo resulted in a significant killing of both AML "bulk" blasts and LSCs, as demonstrated respectively in primary and secondary transplant experiments, using both human and murine AML models. Notably, PNC-27 spares normal HSC activity, as demonstrated in primary and secondary BM transplant experiments of wild-type mice. We concluded that mHDM2 represents a novel and unique therapeutic target, and targeting mHDM2 using PNC-27 selectively kills AML cells, including LSCs, with minimal off-target hematopoietic toxicity.