H2.0-Like Homeobox (HLX) Causes Pre-Leukemic Myeloid Expansion and Initiates AML In Cooperation With FLT3-ITD

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4201-4201
Author(s):  
Ashley Pandolfi ◽  
Boris Bartholdy ◽  
Britta Will ◽  
Robert Stanley ◽  
Tihomira I Todorova ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Overall Survival ◽  
Acute Myeloid Leukemia ◽  
Peripheral Blood ◽  
Myeloid Leukemia ◽  
Cell Level ◽  
Large Numbers ◽  
Differentiation Block ◽  
Acute Myeloid

Abstract Acute myeloid leukemia (AML) is an aggressive disease 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. We have recently reported that the non-clustered homeobox gene, H2.0-like homeobox (HLX), is 2 to 16 fold overexpressed in more than 80% of patients with AML, across all major disease subtypes, and higher levels of HLX are associated with poor overall survival in AML. Inhibition of HLX in both murine and human AML cells has a significant anti-leukemic and differentiation-inducing effect suggesting HLX and its downstream targets as novel therapeutic targets in AML. In order to better understand the role of Hlx at the stem cell level and in myeloid differentiation in vivo, we generated knock-in mice conditionally overexpressing Hlx from the Rosa26 locus and bred them to mice that bear Cre recombinase under the control of the pIpC-inducible, hematopoietic specific promoter, Mx1. Animals overexpressing HLX exhibit elevated WBC counts and abnormal myeloid cells in the peripheral blood. Analysis of the bone marrow reveals expansion of the granulocyte-macrophage progenitor population (lin- ckit+ cd34+ CD16/32high) and expansion of immature myelocytes (ckit+ cd34+ CD16/32high Gr1int). Hlx knock-in bone marrow cells, and specifically immature granulocyte precursors, exhibit enhanced serial clonogenicity in methylcellulose colony assays, and a differentiation block and maintenance of immaturity in response to GM-CSF. Internal tandem duplications of FLT3 (FLT3-ITD) are seen in approximately 30% of all AML patients, and frequently co-occur with elevated HLX levels. 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 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. 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 peripheral blood and bone marrow. We then crossed our new Hlx knock-in mouse model with previously generated FLT3-ITD knock-in mice. Strikingly, heterozygous double-transgenic mice expressing both the knock-in FLT3-ITD mutation and HLX develop acute myeloid leukemia after a latency of 2 months. Morphological and flow cytometric analysis revealed large numbers of blasts circulating in the peripheral blood and replacing the marrow, as well as substantial leukemic infiltrates in the spleen and liver. Our studies reveal a critical role for HLX in conferring a differentiation block and increased clonogenicity at the pre-leukemic stem and progenitor cell level in a genetic in vivo model. Furthermore, a novel compound knock-in mouse model of Hlx overexpression and FLT3-ITD demonstrates that Hlx can initiate AML in cooperation with FLT3-ITD in vivo. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Preclinical Development of Anti-FLT3 CAR-T Therapy for the Treatment of Acute Myeloid Leukemia

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 4-5
Author(s):  
Elina Shrestha ◽  
Raymond Liang ◽  
Carina Sirochinsky ◽  
Ronen Ben Jehuda ◽  
Vladislav Sandler
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Acute Myeloid Leukemia ◽  
Peripheral Blood ◽  
Myeloid Leukemia ◽  
Hematopoietic Stem ◽  
Car T Cells ◽  
Car T ◽  
Acute Myeloid

FMS-like tyrosine kinase 3 (FLT3) is a class III transmembrane receptor tyrosine kinase involved in survival, proliferation, and differentiation of hematopoietic stem/progenitor cells. It is preferentially expressed on the leukemic cells of myeloid lineage including acute myeloid leukemia (AML) and is mutated in approximately one-third of patients with AML, resulting in constitutive signaling associated with poor disease prognosis. Although small molecule inhibitors targeting FLT3 have shown some success in clinical trials, they only work transiently while resistance develops in virtually all patients. The only proven curative treatment for the relapsed or refractory (R/R) AML is allogenic hematopoietic stem cell transplantation (HSCT) which requires highly toxic conditioning regimens often associated with fatal side effects. Thus, there still remains an urgent need for the development of safe yet effective new therapies for the treatment of AML. We developed a novel chimeric antigen receptor modified T (CAR-T) cell therapy targeting FLT3 to eliminate FLT3+ R/R AML leukemia via cytotoxic T lymphocytes (CTL)-mediated cytolysis. Since FLT3 is also expressed on hematopoietic stem cells (HSCs) as well as on early hematopoietic progenitors (HPs), we evaluated the conditioning efficacy of our anti-FLT3 CAR-T in addition to its anti-leukemic activity. We first discovered a novel mouse monoclonal antibody that binds to the extracellular domain of human FLT3 with high affinity (0.8 nM EC50 in FLT3+ leukemic cell line REH) while not competing with FLT3 ligand in order to achieve unobstructed and efficient binding to FLT3. We next generated humanized single-chain variable fragment (scFv) antibodies and characterized their binding affinities. The scFv clone that exhibited highest binding to FLT3 (3.42 nM EC50 in REH cells) was used to design a third generation CAR construct with CD28 and 4-1BB costimulatory and CD3ζ activation domains. T cells isolated from peripheral blood (PB) were transduced with a lentiviral vector encoding the FLT3-CAR. Transduced cells exhibited stable expression of CAR protein and expanded over 120-fold after 18 days in culture. We demonstrated high cytotoxicity of FLT3-CAR-T cells towards AML-derived cell lines in co-culture experiments, even at effector-to-target cells ratios as low as 1:10. In vivo functionality of FLT3-CART was determined by flow cytometry analysis of leukemia burden in the peripheral blood of mice engrafted with GFP+ MOLM-13 (FLT3+ AML cell line) and treated with two doses of 4x106 control or FLT3-CAR-T cells. Compared to control, the appearance of MOLM-13 cells in peripheral blood was significantly delayed in FLT3-CAR-T treated mice. AML progression in mice was also assessed by detection of physical symptoms such as cachexia and hind-leg paralysis in terminal stages. FLT3-CAR-T treatment extended the median survival to 47 days compared to 24 days in control. Moreover, to test if our CAR-T therapy can also efficiently eliminate FLT3+ HSCs and HPs, humanized mice generated by engrafting human cord blood CD34+ cells were injected with autologous control or FLT3-CAR-T cells. Analysis of bone marrow 18 days post treatment, showed that mice that received FLT3-CAR-T cells exhibited dramatically lower frequencies (by 57% in CD38+ and 86% in CD38-) of human CD34+ hematopoietic stem and progenitor cells than control mice, suggesting the potential of CAR-T therapy for HSCT conditioning. In conclusion, our CAR-T therapy shows robust cytolytic activity against FLT3+ cells, demonstrates high efficacy in eradicating FLT3+ R/R AML leukemia in vivo and enables bone marrow conditioning for potentially curative HSCTs by specifically targeting FLT3+ HSCs and early HPs. To prevent the potentially harmful side effects associated with CAR-T therapies, such as cytokine release syndrome and cytotoxicity towards newly transplanted HSCs post conditioning, we are currently testing FLT3-CAR-T cells equipped with inducible caspase9 or EGFRT expression based safety switch to specifically eliminate CAR-Ts by administering FDA-approved small molecules or biologics. Disclosures Shrestha: Hemogenyx Pharmaceuticals LLC: Current Employment. Liang:Hemogenyx Pharmaceuticals LLC: Current Employment. Sirochinsky:Hemogenyx Pharmaceuticals LLC: Current Employment. Ben Jehuda:Hemogenyx Pharmaceuticals LLC: Current Employment. Sandler:Hemogenyx Pharmaceuticals LLC: Current Employment, Current equity holder in publicly-traded company.

scholarly journals A Novel CD49d Targeting Antisense, ATL1102, Effectively Mobilizes Acute Myeloid Leukemia Cells

Blood ◽  
2015 ◽  
Vol 126 (23) ◽  
pp. 3807-3807
Author(s):  
Yann Duchartre ◽  
EunJi Gang ◽  
Hye Na Kim ◽  
Stephanie Nicole Shishido ◽  
Muller Fabbri ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
Acute Myeloid Leukemia ◽  
Cell Line ◽  
Peripheral Blood ◽  
Myeloid Leukemia ◽  
Surface Expression ◽  
Leukemia Cells ◽  
Acute Myeloid

Abstract BACKGROUND: Acute myeloid leukemia (AML) is the most common acute leukemia in adults. Acute myeloid leukemia comprises approximately one-fifth of pediatric leukemias and is the seventh most common pediatric malignancy. In children, relapse following primary therapy approaches 40%, and the 5-year event-free survival (EFS) rate is only approximately 50%. Treatment is dominated by generic chemotherapeutic agents. Novel therapeutic strategies are highly warranted. The bone marrow microenvironment has been shown to promote cell adhesion-mediated drug resistance in leukemia cells. Breaking adhesive bonds of AML cells with their protective niche to mobilize them from the bone marrow to the peripheral blood may make drug treatment more efficient. Our studies have suggested the adhesion molecule CD49d as an anchor molecule for ALL and AML cells in the bone marrow. However, as of today, no drug targeting CD49d is approved for use in leukemia. Here, we evaluate a novel human specific CD49d targeting antisense, ATL1102, in clinical development for Multiple Sclerosis, in human AML cells. METHODS: We determined CD49d expression in the human AML cell line HL-60 treated with a CD49d targeting antisense ATL1102 and antisense control by qPCR and flow cytometry. Annexin V/DAPI and BrdU stainings were used for viability determination and cell cycle assay respectively by flow cytometry. A NOD/SCID IL2Rγ-/- (NSG)xenograft model of human HL-60 cell line was used for an in vivo mobilization assay. RESULTS: To assess the on-target effect of ATL1102 on CD49d, HL-60 cells were nucleoporated with either ATL1102 or control antisense.mRNA expression of CD49dwas significantly decreased by ATL1102 treatment cells (85.2%±15.4 expression inhibition using ATL1102 1µM after 24h compared to control, p<0.001) as assessed by RT-PCR. The FACS analysis 72 hours after treatment revealed a significant decrease of surface expression of CD49d in a dose-dependent manner (99%±0.4 (1µM, *), 87.9%±8.7 (3µM) and 57.8%±7.2 ATL1102 (10µM, ***), 55.9±13.5 (30µM, **) vs 99.7%±0.1 for control antisense (30 µM), P<0.001, n=3). No significant effect on apoptosis or cell cycle was observed after ATL1102 treatment. We also evaluated the in vivo effect of ATL-1102 on mobilization of leukemia cells in a pilot experiment. For this purpose, HL-60 cells (5x106/per mouse) were injected via the tail vein in sublethally irradiated NSG mice. Presence of human ALL cells (hCD45) was determined weekly by flow cytometry of white blood cells isolated from peripheral blood (PB). 23 Days post-leukemia injection, mice were treated with either antisense control (CTRL) (n=3), ATL1102 (50mg/kg, n=2). Peripheral blood was drawn before and 24 hours after ATL1102-treatment. ATL1102 induced a strong mobilization of AML cells to the PB of leukemia-recipient mice compared to control antisense treated-mice (69.1% and 87.7% vs 1.1%, 0.2% and 28.1% for ATL1102 (50mg/ml) and CTRL treated-mice respectively. The mobilized cells show a decrease of surface expression of CD49d (16.8%±9.2% vs 32.8%±16.7%), although this was not of statistical significance in this pilot experiment. Experiments to repeat this assay with large numbers of mice are in progress as well as experiments to determine the initial location of the mobilized AML cells and synergy of ATL1102 with chemotherapy are ongoing. CONCLUSION: We demonstrate that ATL1102 can efficiently decrease CD49d expression in AML cell line in vitro and in vivo, and that ATL1102 leads to mobilization of AML cells to the peripheral blood. Disclosures Wayne: NIH: Patents & Royalties; Medimmune: Honoraria, Other: travel support, Research Funding; Kite Pharma: Honoraria, Other: travel support; Pfizer: Honoraria; Spectrum Pharmaceuticals: Honoraria, Other: travel support, Research Funding. Tachas:Antisense Therapeutics Ltd: Employment, Equity Ownership, Patents & Royalties.

Enasidenib: First Mutant IDH2 Inhibitor for the Treatment of Refractory and Relapsed Acute Myeloid Leukemia

2019 ◽  
Vol 18 (14) ◽  
pp. 1936-1951 ◽  
Author(s):  
Raghav Dogra ◽  
Rohit Bhatia ◽  
Ravi Shankar ◽  
Parveen Bansal ◽  
Ravindra K. Rawal
Keyword(s):  
Clinical Trial ◽  
Bone Marrow ◽  
Overall Survival ◽  
Acute Myeloid Leukemia ◽  
Adverse Effects ◽  
Blood Cells ◽  
Myeloid Leukemia ◽  
White Blood Cells ◽  
Phase Iii ◽  
Acute Myeloid

Background: Acute myeloid leukemia is the collective name for different types of leukemias of myeloid origin affecting blood and bone marrow. The overproduction of immature myeloblasts (white blood cells) is the characteristic feature of AML, thus flooding the bone marrow and reducing its capacity to produce normal blood cells. USFDA on August 1, 2017, approved a drug named Enasidenib formerly known as AG-221 which is being marketed under the name Idhifa to treat R/R AML with IDH2 mutation. The present review depicts the broad profile of enasidenib including various aspects of chemistry, preclinical, clinical studies, pharmacokinetics, mode of action and toxicity studies. Methods: Various reports and research articles have been referred to summarize different aspects related to chemistry and pharmacokinetics of enasidenib. Clinical data was collected from various recently published clinical reports including clinical trial outcomes. Result: The various findings of enasidenib revealed that it has been designed to allosterically inhibit mutated IDH2 to treat R/R AML patients. It has also presented good safety and efficacy profile along with 9.3 months overall survival rates of patients in which disease has relapsed. The drug is still under study either in combination or solely to treat hematological malignancies. Molecular modeling studies revealed that enasidenib binds to its target through hydrophobic interaction and hydrogen bonding inside the binding pocket. Enasidenib is found to be associated with certain adverse effects like elevated bilirubin level, diarrhea, differentiation syndrome, decreased potassium and calcium levels, etc. Conclusion: Enasidenib or AG-221was introduced by FDA as an anticancer agent which was developed as a first in class, a selective allosteric inhibitor of the tumor target i.e. IDH2 for Relapsed or Refractory AML. Phase 1/2 clinical trial of Enasidenib resulted in the overall survival rate of 40.3% with CR of 19.3%. Phase III trial on the Enasidenib is still under process along with another trial to test its potency against other cell lines. Edasidenib is associated with certain adverse effects, which can be reduced by investigators by designing its newer derivatives on the basis of SAR studies. Hence, it may come in the light as a potent lead entity for anticancer treatment in the coming years.

scholarly journals Acute myeloid leukemia induces protumoral p16INK4a-driven senescence in the bone marrow microenvironment

Blood ◽  
2019 ◽  
Vol 133 (5) ◽  
pp. 446-456 ◽  
Author(s):  
Amina M. Abdul-Aziz ◽  
Yu Sun ◽  
Charlotte Hellmich ◽  
Christopher R. Marlein ◽  
Jayna Mistry ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Stromal Cells ◽  
Myeloid Leukemia ◽  
Stromal Cell ◽  
Cell Senescence ◽  
Senescent Phenotype ◽  
Age Related ◽  
Acute Myeloid

Abstract Acute myeloid leukemia (AML) is an age-related disease that is highly dependent on the bone marrow (BM) microenvironment. With increasing age, tissues accumulate senescent cells, characterized by an irreversible arrest of cell proliferation and the secretion of a set of proinflammatory cytokines, chemokines, and growth factors, collectively known as the senescence-associated secretory phenotype (SASP). Here, we report that AML blasts induce a senescent phenotype in the stromal cells within the BM microenvironment and that the BM stromal cell senescence is driven by p16INK4a expression. The p16INK4a-expressing senescent stromal cells then feed back to promote AML blast survival and proliferation via the SASP. Importantly, selective elimination of p16INK4a+ senescent BM stromal cells in vivo improved the survival of mice with leukemia. Next, we find that the leukemia-driven senescent tumor microenvironment is caused by AML-induced NOX2-derived superoxide. Finally, using the p16-3MR mouse model, we show that by targeting NOX2 we reduced BM stromal cell senescence and consequently reduced AML proliferation. Together, these data identify leukemia-generated NOX2-derived superoxide as a driver of protumoral p16INK4a-dependent senescence in BM stromal cells. Our findings reveal the importance of a senescent microenvironment for the pathophysiology of leukemia. These data now open the door to investigate drugs that specifically target the “benign” senescent cells that surround and support AML.

scholarly journals Silencing long non-coding RNA XIST suppresses drug resistance in acute myeloid leukemia through down-regulation of MYC by elevating microRNA-29a expression

2020 ◽  
Vol 26 (1) ◽  
Author(s):  
Chong Wang ◽  
Lingling Li ◽  
Mengya Li ◽  
Weiqiong Wang ◽  
Yanfang Liu ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Drug Resistance ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Bone Marrow Cells ◽  
Cellular Viability ◽  
Down Regulation ◽  
Acute Myeloid

Abstract Background Long non-coding RNAs (lncRNAs) are biomarkers participating in multiple disease development including acute myeloid leukemia (AML). Here, we investigated molecular mechanism of X Inactive-Specific Transcript (XIST) in regulating cellular viability, apoptosis and drug resistance in AML. Methods XIST, miR-29a and myelocytomatosis oncogene (MYC) expression in AML bone marrow cells collected from 62 patients was evaluated by RT-qPCR and Western blot analysis. Besides, the relationship among XIST, miR-29a and MYC was analyzed by dual luciferase reporter assay, RIP, and RNA pull down assays. AML KG-1 cells were treated with anti-tumor drug Adriamycin. The role of XIST/miR-29a/MYC in cellular viability, apoptosis and drug resistance in AML was accessed via gain- and loss-of-function approaches. At last, we evaluated role of XIST/miR-29a/MYC on tumorigenesis in vivo. Results XIST and MYC were up-regulated, and miR-29a was down-regulated in AML bone marrow cells. Silencing XIST inhibited cellular activity and drug resistance but promoted cellular apoptosis of KG-1 cells by down-regulating MYC. XIST inhibited miR-29a expression to up-regulate MYC. Moreover, silencing XIST inhibited tumorigenesis of AML cells in vivo. Conclusions Overall, down-regulation of XIST decreased MYC expression through releasing the inhibition on miR-29a, thereby reducing drug resistance, inhibiting viability and promoting apoptosis of AML cells.

scholarly journals Results from a randomized trial of salvage chemotherapy followed by lestaurtinib for patients with FLT3 mutant AML in first relapse

Blood ◽  
2011 ◽  
Vol 117 (12) ◽  
pp. 3294-3301 ◽  
Author(s):  
Mark Levis ◽  
Farhad Ravandi ◽  
Eunice S. Wang ◽  
Maria R. Baer ◽  
Alexander Perl ◽  
...  
Keyword(s):  
Overall Survival ◽  
Acute Myeloid Leukemia ◽  
Complete Remission ◽  
Randomized Trial ◽  
Myeloid Leukemia ◽  
Remission Rate ◽  
Platelet Recovery ◽  
First Relapse ◽  
Acute Myeloid

AbstractIn a randomized trial of therapy for FMS-like tyrosine kinase-3 (FLT3) mutant acute myeloid leukemia in first relapse, 224 patients received chemotherapy alone or followed by 80 mg of the FLT3 inhibitor lestaurtinib twice daily. Endpoints included complete remission or complete remission with incomplete platelet recovery (CR/CRp), overall survival, safety, and tolerability. Correlative studies included pharmacokinetics and analysis of in vivo FLT3 inhibition. There were 29 patients with CR/CRp in the lestaurtinib arm and 23 in the control arm (26% vs 21%; P = .35), and no difference in overall survival between the 2 arms. There was evidence of toxicity in the lestaurtinib-treated patients, particularly those with plasma levels in excess of 20μM. In the lestaurtinib arm, FLT3 inhibition was highly correlated with remission rate, but target inhibition on day 15 was achieved in only 58% of patients receiving lestaurtinib. Given that such a small proportion of patients on this trial achieved sustained FLT3 inhibition in vivo, any conclusions regarding the efficacy of combining FLT3 inhibition with chemotherapy are limited. Overall, lestaurtinib treatment after chemotherapy did not increase response rates or prolong survival of patients with FLT3 mutant acute myeloid leukemia in first relapse. This study is registered at www.clinicaltrials.gov as #NCT00079482.

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