scholarly journals The miRNA-193 Family Is a Potent Tumor-Suppressor and a Biomarker for Poor Prognosis in Acute Myeloid Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 1534-1534
Author(s):  
Razan Jammal ◽  
Kathrin Krowiorz ◽  
Nadine Haetscher ◽  
Stephan Emmrich ◽  
Arefeh Rouhi ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Poor Prognosis ◽  
Mapk Signaling ◽  
Leukemic Cells ◽  
Hematopoietic Stem ◽  
Acute Myeloid ◽  
Potent Tumor

Abstract Deregulated microRNA (miRNA) expression has been implicated in the pathogenesis of acute myeloid leukemia (AML). We previously showed that miR-193b is a STAT5-regulated miRNA that controls hematopoietic stem and progenitor cell (HSPC) expansion by modulating cytokine receptor signaling. Here we demonstrate that the miR-193 family members miR-193a and 193b are potent tumor suppressors in AML. Both miRNAs were downregulated in several cytogenetically-defined subgroups of pediatric and adult AML (n=202), whereas low miR-193b expression was an independent indicator for poor prognosis and survival. Accordingly, ectopic retroviral Hoxa9-Meis1 expression in HSPCs from miR-193b-/- mice resulted in a more aggressive disease with significantly shortened latency and survival as compared to miR-193bWT/WT HSPCs. Inversely, ectopic miR-193 expression in leukemic cells belonging to various AML subgroups decreased leukemic growth in vitro and prolonged survival of mice suffering from Hoxa9-Meis1-induced leukemia through a G1/S phase block. These effects were mediated by targeting c-KIT, KRAS and SOS2 - key factors of the KIT-RAS-RAF-MEK-ERK signaling cascade - as well as the downstream cell cycle regulator CCND1. Knockdown of each of these genes partially recapitulated the anti-proliferative effect of ectopic lentiviral miR-193 expression. As the tumor suppressive function is independent of patient age or AML cytogenetic background, these observations suggest an opportunistic role for miR-193 in future AML therapies. With the notion that a single miRNA can control aberrant MAPK signaling at multiple levels, restoring miR-193 expression in AML cells with constitutive activation of this cascade would assure high antileukemic efficacy, while avoiding the fast development of resistance mechanisms. Disclosures Heuser: Bayer Pharma AG: Research Funding; Novartis: Consultancy, Research Funding; BerGenBio: Research Funding; Tetralogic: Research Funding; Karyopharm Therapeutics Inc: Research Funding; Celgene: Honoraria; Pfizer: Research Funding. Mulaw:NuGEN: Honoraria. Baruchel:Jazz: Consultancy; Servier: Consultancy; Celgene: Consultancy; Novartis: Consultancy; Baxalta: Research Funding.

Selective Ablation of Acute Myeloid Leukemia Using Antibody-Targeted Chemotherapy: A Phase I Study of an Anti-CD33 Calicheamicin Immunoconjugate

Blood ◽  
1999 ◽  
Vol 93 (11) ◽  
pp. 3678-3684 ◽  
Author(s):  
E.L. Sievers ◽  
F.R. Appelbaum ◽  
R.T. Spielberger ◽  
S.J. Forman ◽  
D. Flowers ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
High Rate ◽  
Leukemic Cells ◽  
Antitumor Antibiotic ◽  
Dose Escalation Study ◽  
Hematopoietic Stem ◽  
Selective Ablation ◽  
Acute Myeloid

Abstract Leukemic blast cells express the CD33 antigen in most patients with acute myeloid leukemia (AML), but this antigen is not expressed by hematopoietic stem cells. We conducted a study to determine whether normal hematopoiesis could be restored in patients with AML by selective ablation of cells expressing the CD33 antigen. In a dose escalation study, 40 patients with relapsed or refractory CD33+ AML were treated with an immunoconjugate (CMA-676) consisting of humanized anti-CD33 antibody linked to the potent antitumor antibiotic calicheamicin. The capacity of leukemic cells to efflux 3,3’-diethyloxacarbocyanine iodide (DiOC2) was used to estimate pretreatment functional drug resistance. Leukemia was eliminated from the blood and marrow of 8 (20%) of the 40 patients; blood counts returned to normal in three (8%) patients. A high rate of clinical response was observed in leukemias characterized by low dye efflux in vitro. Infusions of CMA-676 were generally well tolerated, and a postinfusion syndrome of fever and chills was the most common toxic effect. Two patients who were treated at the highest dose level (9 mg/m2) were neutropenic >5 weeks after the last dose of CMA-676. These results show that an immunoconjugate targeted to CD33 can selectively ablate malignant hematopoiesis in some patients with AML.

scholarly journals Combination of BCL-2 Inhibition and Triptolide Causes Synthetic Lethality in Acute Myeloid Leukemia through Preventing Reciprocal Resistance

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2083-2083
Author(s):  
Bing Xu ◽  
Yuanfei Shi ◽  
Long Liu ◽  
Bing Z Carter
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Synthetic Lethality ◽  
Leukemic Cells ◽  
Apoptotic Pathway ◽  
P53 Status ◽  
Acute Myeloid

BCL-2 inhibition exerts effective pro-apoptotic activities in acute myeloid leukemia (AML) but clinical efficacy as a monotherapy was limited in part due to the treatment-induced MCL-1 increase. Triptolide (TPL) exhibits anti-tumor activities in part by upregulating pro-apoptotic BCL-2 proteins and decreasing MCL-1 expression in various malignant cells. We hypothesized that combined BCL-2 inhibition and TPL exert synergistic anti-leukemia activities and prevent the resistance to BCL-2 inhibition in AML. We here report that TPL combined with BCL-2 inhibitor ABT-199 synergistically induced apoptosis in leukemic cells regardless of p53 status through activating the intrinsic mitochondrial apoptotic pathway in vitro. Although ABT-199 or TPL alone inhibited AML growth in vivo, the combination therapy demonstrated a significantly stronger anti-leukemic effect. Mechanistically, TPL significantly upregulated BH3 only proteins including PUMA, NOXA, BID and BIM and decreased MCL-1 but upregulated BCL-2 expression in both p53 wild type and p53 mutant AML cell lines, while the combination decreased both BCL-2 and MCL-1 and further increased BH3 only BCL-2 proteins. MCL-1 and BCL-2 increases associated with respective ABT-199 and TPL treatment and resistance were also observed in vivo. Significantly downregulating MCL-1 and elevating BH3 only proteins by TPL could not only potentially block MCL-1-mediated resistance but also enhance anti-leukemic efficacy of ABT-199. Conversely, BCL-2 inhibition counteracted the potential resistance of TPL mediated by upregulation of BCL-2. The combination further amplified the effect, which likely contributed to the synthetic lethality. This mutual blockade of potential resistance provides a rational basis for the promising clinical application of TPL and BCL-2 inhibition in AML independent of p53 status. Disclosures Carter: Amgen: Research Funding; AstraZeneca: Research Funding; Ascentage: Research Funding.

scholarly journals Novel Therapeutic Targeting of UHRF1 Restores 5'-Azacytidine Response in Resistant Acute Myeloid Leukemia

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1356-1356
Author(s):  
Anup Kumar Singh ◽  
Xiaochun Yu
Keyword(s):  
Dna Methylation ◽  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Antiproliferative Effect ◽  
Leukemic Cells ◽  
Hematopoietic Stem ◽  
Dna Strand ◽  
Acute Myeloid

Abstract DNA hypermethylation plays a pivotal role in the pathogenesis of acute myeloid leukemia (AML). Most of the recurrent driver mutations and chromosomal translocations in AML involve genes encoding chromatin modifiers and DNA methylation relevant enzymes. Hypo-methylating drugs such as 5-Azacytidine (AZA) that target DNMTs prolong overall survival in AML patients. However, their long term treatments lead to emergence of acquired therapy resistance mostly through unknown mechanisms and hence there is an urgent need for alternate therapeutics to address AZA resistance in AML patients. Recently, it has been shown that AZA resistant leukemic cells are relatively quiescent with higher expression of many components of DNA methylation machinery that also includes UHRF1 (ubiquitin-like with PHD and ring finger domains 1). UHRF1 is a key epigenetic modulator that regulates DNA methylation and gene expression. It is a multi-domain nuclear protein with an SRA (SET-and-RING-associated) domain to recognize hemi-methylated DNA immediately after replication. It plays a crucial role in the maintenance of DNA methylation by recruiting DNMT1 to replication sites and facilitates methylation on newly synthesized DNA strand. UHRF1 is frequently overexpressed in multiple human neoplasms including AML and in the absence of UHRF1, hematopoietic stem cells undergo erythroid-biased differentiation at the expense of self-renewal capacity. Despite UHRF1 being key a therapeutic target against AML, specific, and cell-permeable inhibitors of UHRF1 have not been identified yet. In this study, we hypothesized that targeting UHRF1 using novel small molecule inhibitor will interfere with DNMT1-dependent DNA methylation at newly synthesized DNA strand, which may further synergize with antiproliferative effect of classical DNMT inhibitors in AML cells. In this study, we used in silico strategy to discover novel putative UHRF1 inhibitors by screening NCI compound database. For in vitro validation, we have first purified the SRA domain of UHRF1 followed by analysis of total DNA methylation levels using 5'-methyl cytosine (5mC) dot blot in the presence of each inhibitor. After a series of stringent in vitro and cell based assays we have identified lead compound 20 (C20) as a potent UHRF1 inhibitor which suppresses DNA methylation without affecting DNMTs in leukemic cells. Specificity of C20 against SRA domain was further established by isothermal titration calorimetry (ITC). We next found that C20 treatment significantly decreased UHRF1 and DNMT1 foci formation in the nucleus of mouse embryonic fibroblast and stem cells. Based on the its critical role in DNA methylation and enhanced expression in resistant cells, we assumed that AZA resistance in AML may be mediated by UHRF1 and C20 might restore AZA sensitivity by attenuating enhanced UHRF1 activity. To validate this, we pretreated AZA resistant leukemic cells (HL60R) with suboptimal dose of C20 followed by AZA treatment. Interestingly, we found a synergistic increase in antiproliferative effect by flow cytometry and colony formation assay. By analyzing the surface expression of myeloid differentiation markers, we found that C20 treatment promotes differentiation and decreases quiescent leukemic cell population. In conclusion, we report a novel UHRF1 inhibitor as a sensitizer of resistant AML cells towards AZA treatment potentially by promoting differentiation, suggesting a novel combination approach for future clinical evaluations. Disclosures No relevant conflicts of interest to declare.

High Disease-Free and Overall Survival Rate Following Allogeneic Hematopoietic Stem Cell Transplantation for FLT3-Mutated Acute Myeloid Leukemia Even in Non-Remission Status

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2283-2283 ◽  
Author(s):  
Aya Nishida ◽  
Mitsuhiro Yuasa ◽  
Kosei Kageyama ◽  
Kazuya Ishiwata ◽  
Shinsuke Takagi ◽  
...  
Keyword(s):  
Overall Survival ◽  
Acute Myeloid Leukemia ◽  
Stem Cell ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Poor Prognosis ◽  
Hematopoietic Stem ◽  
Remission Status ◽  
Disease Free ◽  
Acute Myeloid

Abstract [Background] FMS like tyrosine kinase 3 (FLT3) mutations occur in about 30% of patients with acute myeloid leukemia (AML). Patients with FLT3-mutated AML have a poor prognosis and are referred for early allogeneic hematopoietic stem cell transplantation (allo-HSCT) in first complete remission (CR1). So far, there is still limited data available on allo-HSCT for FLT3-mutated AML in non-remission status. [Objective and method] To assess the clinical features and outcome of allo-HSCT for FLT3-mutated AML, we retrospectively analyzed patients underwent first allo-HSCT for FLT3-mutated AML excluding acute promyelocytic leukemia (FAB M3) from January 2011 to March 2016. [Result] During the study period, 332 patients received first allo-HSCT for AML in our institute. One hundred and thirty-eight were tested for the presence of FLT3-mutation and 35 showed positive results and were subjected to the analysis. The median follow-up day of survivors was 602 (101-1867). The median age of the patients was 55 years (range, 21-72). Twenty-one patients had de novo AML, 12 had AML with myelodysplasia related changes, and 2 had therapy related AML. Eighteen had normal karyotype, 4 had complex, and 13 had others. Seven were in remission (5 in CR1, and 2 in CR2), and 28 were in non-remission (8 in primary induction failure, 13 in relapse 1, and 7 in chemo naïve status). Twenty-nine patients used unrelated cord blood, 2 did unrelated bone marrow, and 4 did related peripheral blood stem cell as grafts. All but 1 received myeloablative pretransplant conditionings. At 2 years after transplantation, overall survival (OS), disease free survival (DFS), relapse rate (RR), and non-relapse mortality (NRM) of whole studied population were 65.9%, 50.2%, 28.4%, and 21.4%, respectively. Among those in non-remission before transplantation, OS, DFS, RR, and NRM at 2 years post-transplant were 62.2% (Figure 1A), 49.9%(Figure 1B), 24.3%, and 25.8%, respectively. Only younger age (<55 years) was the factor associated with better OS with statistical significance in multivariate analysis. [Conclusion] Our data indicated that allo-HSCT could overcome the poor prognosis of FLT3-mutated AML even for those in non-remission status, despite the profound chemo-resistant character of FLT3-mutated AML. Figure 1A Figure 1A. Figure 1B Figure 1B. Disclosures Izutsu: Abbvie: Research Funding; Gilead: Research Funding; Celgene: Research Funding; Janssen Pharmaceutical K.K.: Honoraria; Eisai: Honoraria; Kyowa Hakko Kirin: Honoraria; Chugai Pharmaceutical: Honoraria, Research Funding; Takeda Pharmaceutical: Honoraria; Mundipharma KK: Research Funding.

scholarly journals Evaluation of a Bifunctional Sirpα-CD123 Fusion Antibody for the Elimination of Acute Myeloid Leukemia Stem Cells

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2544-2544 ◽  
Author(s):  
Siret Tahk ◽  
Saskia Schmitt ◽  
Christian Peter Augsberger ◽  
Binje Vick ◽  
Laia Pascual Ponce ◽  
...  
Keyword(s):  
Stem Cells ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Ex Vivo ◽  
Regulatory Protein ◽  
Target Antigen ◽  
Hematopoietic Stem ◽  
Acute Myeloid

Background: Despite considerable advances in the development of novel strategies for the treatment of acute myeloid leukemia (AML) the relapse rate is still high with only limited treatment options. Relapse occurs due to the persistence of chemotherapy-resistant leukemic stem cells (LSCs), which re-initiate outgrowth of the disease, highlighting the need of targeting LSCs to improve overall survival. Immunotherapies represent a promising strategy to target chemotherapy-resistant LSCs in AML. LSCs are characterized by the expression of the interleukin-3 receptor α, also known as CD123. CD123 is expressed on AML blasts and LSCs, and shows only a moderate expression on normal hematopoietic stem cells, claiming CD123 as a suitable target antigen (Haubner et al, Leukemia 2019). CD47, known as a marker of self, is also highly expressed on LSCs as immune escape mechanism. CD47 transmits a "don't eat me" signal upon its interaction with the myeloid-specific signal regulatory protein alpha (SIRPα) receptor on macrophages, thus inhibiting phagocytosis. In order to efficiently eliminate LSCs and provide AML patients a possibility for prolonged relapse-free survival, we have designed a bifunctional antibody that specifically targets CD123 and simultaneously blocks CD47. Importantly, our strategy restricts the benefits of the CD47 blockade to CD123 positive AML cells. Thus, we hypothesize a lower risk for on-target off-leukemia toxicity. Methods: The bifunctional SIRPα-CD123 antibody was generated by fusing the endogenous extracellular domain of SIRPα, which functions as the CD47 blocking domain, to an CD123 antibody CD123. We assessed the selective binding of the bifunctional antibody to CD123+CD47+ AML-derived cells and the ability to block CD47 on CD123+ cells in vitro. Furthermore, the biological activity of the SIRPα-CD123 antibody was examined using the AML-derived cell line MOLM-13, patient-derived xenografted (PDX) AML cells as well as primary cells from patients with newly diagnosed or relapsed AML. Results: We engrafted the endogenous SIRPα V-like domain to an antibody targeting CD123, which improved the binding of the bifunctional SIRPα-CD123 antibody to AML cells compared to a conventional CD123 antibody (MFI ratioCD123 = 2.46 0.25 vs MFI ratioSIRPα-CD123 = 4.44 0.60). The SIRPα-CD123 antibody enhanced the elimination of the AML-derived MOLM-13 cells by antibody-dependent cellular cytotoxicity (EC50CD123 = 38.5 pM vs EC50SIRPα-CD123 = 10.1 pM, n = 9). Additionally, the cytotoxicity was confirmed using primary patient-derived AML cells ex vivo. Further, an improved ex vivo cytotoxicity towards AML PDX cells was observed with the SIRPα-CD123 antibody (% lysis at 100 nM: 14.27 5.40 vs 42.94 10.21 for CD123 and SIRPα-CD123 antibodies respectively, n = 3). With regards to the inhibition of CD47 signaling, we were able to show a blockade of CD47 on CD123+CD47+ positive cells by the SIRPα-CD123 antibody. Correspondingly, a significant increase in phagocytosis of primary patient-derived AML cells mediated by monocyte-derived macrophages was observed in allogenic as well as autologous settings (% phagocytosis, normalized to isotype control and maximum phagocytosis in an autologous setting: 20.11 4.59 vs 90.37 6.22, n = 5 for CD123 and SIRPα-CD123 antibodies, respectively). We were further able to show a preferential binding to MOLM-13 in the presence of a 20-fold excess of red blood cells indicating a potential low on-target off-leukemia toxicity. Taken together, our in vitro data supports the elimination of the CD123+CD47+ positive AML LSC compartment by a synergistic effect of avidity-dependent binding to CD123 and CD47 and the simultaneous inhibition of the innate immune CD47-SIRPα signaling pathway. Conclusions: The SIRPα-CD123 is a bifunctional antibody with the potential to deplete CD123+CD47+ AML LSCs by a dual mode of action mechanism resulting in NK cell dependent cytotoxicity and macrophage-mediated phagocytosis. By combining a high affinity binding to CD123+ cells and a low affinity CD47 blockade that is restricted to CD123+ cancer cells we effectively minimize the risk for CD47-related on-target off-leukemia toxicity. The results of our in vitro assays using AML cell lines are consistent with the data from PDX and primary AML samples and support further preclinical testing of the SIRPα-CD123 antibody in vivo. Disclosures Subklewe: Miltenyi: Research Funding; Pfizer: Consultancy, Honoraria; Gilead: Consultancy, Honoraria, Research Funding; AMGEN: Consultancy, Honoraria, Research Funding; Oxford Biotherapeutics: Research Funding; Roche: Consultancy, Research Funding; Celgene: Consultancy, Honoraria; Morphosys: Research Funding; Janssen: Consultancy.

scholarly journals the Role of MSCs in the Development of Acute Myeloid Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2669-2669
Author(s):  
Yahya Saleh Al-Matary ◽  
Lacramioara Botezatu ◽  
Robert Fernando Lams ◽  
Aniththa Thivakaran ◽  
Renata Köster ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Research Funding ◽  
Leukemic Cells ◽  
Cell Contact ◽  
Dependent Manner ◽  
Therapeutic Approaches ◽  
New Therapeutic Approaches ◽  
Acute Myeloid

Abstract Acute myeloid leukemia (AML) is a malignant disease of the bone marrow. The prognosis of AML is still poor with only 25% of patients living longer than 5 years. Thus, new therapeutic approaches are warranted to improve patients' survival. The growth of AML cells not only depends on cell intrinsic factors, but is also supported by stroma cells, among them mesenchymal stem cells (MSCs). We reported here that MSCs derived from human AML patients or murine models of human AML better supported the in vitro growth of leukemic cells than MSCs from non-leukemic patients or mice and this is dependent on cell-to-cell contact. Similarly, immortalized MSCs lines derived from AML patients supported the growth of human AML cell lines better than a MSC line originating from a healthy donor. In addition, the frequency of MSCsin the BM of leukemic mice was increased. On a molecular level, the polarization of MSCs towards an AML-supporting state depended on the expression of the transcription factor Growth factor independence 1 (Gfi1). Loss of Gfi1 abrogated the tumor-supporting state of AML-associated MSCs in vitro and in vivo. In summary, MSCs from AML patients support the growth of AML cells in vitro in a Gfi1-dependent manner which could open the path to new therapeutic approaches. Disclosures Dührsen: Amgen: Honoraria, Research Funding; Alexion Pharmaceuticals: Honoraria, Research Funding; Roche: Honoraria, Research Funding. Khandanpour:Hospital of Essen university: Research Funding; Max-Eder: Research Funding.

H2.0-Like Homeobox (HLX) Induces Unlimited Clonogenicity, Blocks Differentiation, and Cooperates with FLT3-ITD in the Induction of Acute Myeloid Leukemia

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 651-651
Author(s):  
Ashley Pandolfi ◽  
Boris Bartholdy ◽  
Masahiro Kawahara ◽  
Laura Barreyro ◽  
Britta Will ◽  
...  
Keyword(s):  
Overall Survival ◽  
Acute Myeloid Leukemia ◽  
Dna Binding ◽  
Myeloid Leukemia ◽  
Poor Prognosis ◽  
Target Genes ◽  
Hematopoietic Stem ◽  
Differentiation Block ◽  
Acute Myeloid

Abstract Abstract 651 Acute myeloid leukemia (AML) is an aggressive disease which is associated with poor clinical outcome. Less than one third of patients achieve durable remission with current treatment regimens, and prognostication and risk stratification are challenging. Identification and functional studies of genes and pathways which regulate leukemic transformation and maintenance is instrumental to understanding the pathogenesis of AML and for development of novel therapeutic strategies. Several members of the Hox (class I homeobox) family of transcription factors have been implicated in the regulation of normal hematopoiesis and leukemogenesis. Less is known about the role of non-clustered (class II) homeobox genes. We found that a new non-clustered homeobox gene, H2.0-like homeobox (HLX), regulates early hematopoiesis and promotes AML in mice and humans. HLX is 2 to 16 fold overexpressed in more than 80% of patients with AML, across all major disease subtypes. Higher levels of HLX are associated with poor overall survival in 3 different, large cohorts of AML patients (N=601, p=2.3×10−6), and HLX holds up as an independent prognostic factor in a multivariate analysis. ShRNA-mediated inhibition of HLX in both murine and human AML cells significantly inhibits leukemic growth and clonogenic capacity, and overcomes the differentiation block of AML cells. When we analyzed pre-leukemic hematopoietic stem and progenitor cells (HSPC) in a PU.1 URED/D AML mouse model, we found a 4-fold elevation of Hlx, suggesting that Hlx is involved in malignant transformation. Overexpression of HLX in wildtype HSPC in a competitive, congenic transplantation model led to near complete depletion of long-term HSC and 16-fold enrichment of myeloid progenitors with a surface phenotype slightly past the GMP stage (CD45+Kit−CD34−CD44highCD49bhighCD11bmid). Overexpression of HLX in HSPC in vitro led to a myeloid differentiation block and to formation of aberrant, CD34−Kit− progenitors with unlimited serial clonogenicity. The mechanism of action of Hlx is so far unknown. The presence of a C-terminal homeobox domain suggests Hlx may directly interact with DNA, however, no studies have shown DNA binding by Hlx or identified direct Hlx target genes. We find that mutation of only two residues of the Hlx homeodomain is sufficient to completely abrogate the differentiation block induced by HLX overexpression in HSPC, indicating Hlx is acting through the DNA-binding ability of its homeodomain. Furthermore, we have now identified direct HLX target genes in both HSPC and AML cells using a combination of expression microarrays and chromatin-immunoprecipitation (chIP). We find that HLX regulates a set of genes which mediate its leukemia-promoting functions, such as BTG1, and we have used chIP to identify a subset of these genes, including PAK1, that are direct targets of HLX. Internal tandem duplications of FLT3 (FLT3-ITD) are seen in approximately 25% of all AML patients, and confer a poor prognosis. Correlative analyses showed that AML patients with mutant FLT3 and low HLX have overall survival similar to WT FLT3 patients, and survive significantly longer than patients with mutant FLT3 and high HLX (p=0.005), demonstrating that FLT3 mutations confer poor prognosis only if HLX is highly expressed, and suggesting that HLX and mutant FLT3 functionally cooperate. We find that co-expression of HLX and FLT3-ITD leads to dramatically enhanced cytokine independent growth and clonogenicity of 32D cells as well as primary murine HSPC in vitro. When we retrovirally co-expressed HLX and FLT3-ITD, or FLT3-ITD alone (plus an empty control), in primary Lin−Kit+ cells and transplanted them into congenic recipient animals, we found that four weeks after transplantation donor chimerism was 4-fold increased on average in the peripheral blood (PB) and bone marrow (BM), and by 12 weeks post-transplantation mice expressing FLT3-ITD and HLX developed AML with large numbers of leukemic blasts in the PB and BM. We have generated knock-in mice conditionally overexpressing Hlx from the Rosa26 locus and ongoing studies include crossing these mice into FLT3-ITD knock-in animals. In summary, our studies have identified HLX as a novel key transcription factor involved in the regulation of early hematopoiesis and AML pathogenesis, and suggest HLX and downstream pathways as promising new therapeutic targets in AML. Disclosures: No relevant conflicts of interest to declare.

Selective Ablation of Acute Myeloid Leukemia Using Antibody-Targeted Chemotherapy: A Phase I Study of an Anti-CD33 Calicheamicin Immunoconjugate

Blood ◽  
1999 ◽  
Vol 93 (11) ◽  
pp. 3678-3684 ◽  
Author(s):  
E.L. Sievers ◽  
F.R. Appelbaum ◽  
R.T. Spielberger ◽  
S.J. Forman ◽  
D. Flowers ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
High Rate ◽  
Leukemic Cells ◽  
Antitumor Antibiotic ◽  
Dose Escalation Study ◽  
Hematopoietic Stem ◽  
Selective Ablation ◽  
Acute Myeloid

Leukemic blast cells express the CD33 antigen in most patients with acute myeloid leukemia (AML), but this antigen is not expressed by hematopoietic stem cells. We conducted a study to determine whether normal hematopoiesis could be restored in patients with AML by selective ablation of cells expressing the CD33 antigen. In a dose escalation study, 40 patients with relapsed or refractory CD33+ AML were treated with an immunoconjugate (CMA-676) consisting of humanized anti-CD33 antibody linked to the potent antitumor antibiotic calicheamicin. The capacity of leukemic cells to efflux 3,3’-diethyloxacarbocyanine iodide (DiOC2) was used to estimate pretreatment functional drug resistance. Leukemia was eliminated from the blood and marrow of 8 (20%) of the 40 patients; blood counts returned to normal in three (8%) patients. A high rate of clinical response was observed in leukemias characterized by low dye efflux in vitro. Infusions of CMA-676 were generally well tolerated, and a postinfusion syndrome of fever and chills was the most common toxic effect. Two patients who were treated at the highest dose level (9 mg/m2) were neutropenic >5 weeks after the last dose of CMA-676. These results show that an immunoconjugate targeted to CD33 can selectively ablate malignant hematopoiesis in some patients with AML.

scholarly journals Acute myeloid leukemia cells are targeted by the naturally occurring CXCR4 antagonist EPI-X4

2021 ◽  
Author(s):  
Lisa M. Kaiser ◽  
Mirja Harms ◽  
Daniel Sauter ◽  
Vijay PS Rawat ◽  
Mirco Glitscher ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Mapk Signaling ◽  
Cxcr4 Antagonist ◽  
Hematopoietic Stem ◽  
Nicotinamide Phosphoribosyltransferase ◽  
Naturally Occurring ◽  
Acute Myeloid

AbstractThe G protein-coupled receptor (GPCR) and chemokine receptor CXCR4 plays an essential role in tumor initiation and maintenance. This is exemplified in acute myeloid leukemia (AML), where CXCL12-mediated CXCR4 signaling plays a pivotal role for the crosstalk between leukemic stem cells and their microenvironmental niche. Despite the key role of CXCR4 in cancer, surprisingly little is known about endogenous mechanisms that specifically target CXCR4 and dampen its activity. Here, we demonstrate that the naturally occurring peptide and CXCR4 antagonist EPI-X4 and its optimized derivatives effectively blocks CXCL12-mediated migration of AML cells towards a CXCL12 gradient and impairs growth of AML cells in vitro and in vivo in contrast to normal hematopoietic stem and progenitor cells. This anti-leukemic activity of EPI-X4 was accompanied by suppression of CXCR4-mediated MAPK signaling. Of note, EPI-X4 suppressed metabolic pathways and induced depletion of intracellular nicotinamide phosphoribosyltransferase (iNAMPT) in AML cells, linking anti-CXCR4 activity to shifts in NAD+ metabolism.

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