ALBERT

Description: Acute myeloid leukemia (AML) is a neoplastic disorder resulting from clonal proliferation of poorly differentiated immature myeloid cells. Distinct genetic and epigenetic aberrations are key features of AML that account for its variable response to standard therapy. Irrespective of their oncogenic mutations, AML cells produce elevated levels of reactive oxygen species (ROS). They also alter expression and activity of antioxidant enzymes to promote cell proliferation and survival. Subsequently, selective targeting of redox homeostasis in a molecularly heterogeneous disease, such as AML, has been an appealing approach in the development of novel anti-leukemic chemotherapeutics. Naphthoquinones are able to undergo redox cycling and generate ROS in cancer cells, which have made them excellent candidates for testing against AML cells. In addition to inducing oxidative imbalance in AML cells, depending on their structure, naphthoquinones negatively affect other cellular apparatus causing neoplastic cell death. Here we provide an overview of the anti-AML activities of naphthoquinone derivatives, as well as analysis of their mechanism of action, including induction of reduction-oxidation imbalance, alteration in mitochondrial transmembrane potential, Bcl-2 modulation, initiation of DNA damage, and modulation of MAPK and STAT3 activity, alterations in the unfolded protein response and translocation of FOX-related transcription factors to the nucleus.

Description: Despite recent advancements, approximately 50% of patients with acute myeloid leukemia (AML) do not respond to induction therapy (primary induction failure, PIF) or relapse after

Description: Abstract 2624 Introduction: The incidence of mutations in IDH1 and IDH2 (mIDH) in de novo AML is 10–15%. These mutations are enriched in normal karyotype AML, and their presence carries an unfavorable prognostic factor, according to some studies. Furthermore, mutations in IDH1/2 genes have been identified in approximately 5% of myelodysplastic syndromes and 10% of myeloproliferative neoplasms. Although wild-type IDH in cytosol and mitochondria catalyze the conversion of isocitrate to α-ketoglutarate (α-KG) with the production of NADPH, altered amino acids in mIDH1 and mIDH2 reside in the catalytic pocket and result in a neoenzymatic activity, converting α-KG to 2-hydroxyglutarate with the consumption of NADPH. The primary source for α-KG for these cells is glutamine, which is first converted to glutamate by glutaminase and subsequently to α-KG. Because glutamine is the primary source for α-KG, we hypothesized that cells with mIDH are in essence addicted to glutamine via glutaminase activity, such that depletion of glutamine or interruption of its metabolism would be deleterious to cellular metabolism and survival. The aim of this study was to investigate whether inhibition of glutaminase by a small molecule, BPTES (bis-2-[5-(phenylacetamido)-1,3,4-thiadiazol-2-yl]ethyl sulfide), could selectively kill primary AML cells with mIDH1, but not IDH-wild type AML cells. We and others have previously demonstrated that BPTES inhibits glutaminase effectively. Method: Two independent sets of experiments were performed by two separate research groups. One group was blinded to mutant versus wild type IDH status. The other group was blinded to drug identity including solvent versus BPTES and to various BPTES concentrations. Primary AML cells from patients were cultured in RPMI-1640 medium with 20% fetal bovine serum, 20% 5637 cell-conditioned medium and 1% antibiotics with no drug, DMSO control (0.1% concentration) and 20 or 40 microM BPTES. Cells were counted manually on days 2, 4 and 6. Growth curves were generated for viable cells as assessed by trypan blue exclusion. Experiments were performed in triplicates. Results: Growth curves of primary AML cells (with mutation status indicated) with no drug and with DMSO or BPTES (20 or 40 microM) are shown in Figure 1. Cells #2, #3, #5 and #10 carried IDH1 mutations. Cells #4 and #9 were wild type. On day 4, there was approximately a two-fold decrease in the growth of all IDH-mutant AML cells exposed to 20 microM BPTES compared to DMSO. No significant difference in activity was observed between 20 and 40 microM of BPTES. There was no difference in cell growth between exposure to no drug and to DMSO. The growth of wild type AML cells was not significantly affected by the glutaminase inhibitor. Results were consistent between the two research groups. Conclusions: Although IDH mutations are frequently found in AML, a therapeutic strategy targeted at these mutations has not been reported. To the best of our knowledge, this is the first report of a targeted approach to the treatment of IDH-mutant AML. We found that inhibition of glutaminase by a small molecule, BPTES, preferentially slows the growth of primary AML cells with mutant IDH1 versus those AML cells with wild type IDH. Further investigation in xenograft models and pharmacologic studies are ongoing. Disclosures: No relevant conflicts of interest to declare.

Description: Background The oxidative state is significantly perturbed in leukemia cells, compared to normal cells, due to generation of increased reactive oxygen species (ROS) and/or dysregulated antioxidant mechanisms. In a molecularly heterogeneous disease such as acute myeloid leukemia (AML), targeting the oxidative state, a fundamental physiological property, is an attractive strategy for developing novel anti-leukemic agents. We hypothesized that regardless of oncogenic mutations, therapeutic augmentation of ROS in AML cells with dysregulated antioxidants would kill leukemia cells and leukemia stem cells, while normal stem cells would remain relatively intact. Quinones can initiate and propagate free radical reactions. The electron-accepting nature of quinones could in principle be tuned to yield selective cytotoxicity for cells with a particular redox signature. Dimeric naphthoquinones (BiQs), with known ability to generate ROS in cancer cells, are a novel class of compounds with unique characteristics that make them excellent candidates to be tested against leukemia cells. The primary objective of this study was to determine the potency of BiQs in leukemia cells and to assess the therapeutic index of BiQs in AML cells, in relation to normal hematopoietic stem cells. The secondary objective was to determine whether BiQs induce apoptosis, increase ROS, target mitochondrial membrane potential, and/or affect antioxidant proteins. Methods We tested two BiQs (E6a and B1a) and one mononaphthoquinone in two AML cell lines, MOLM-14 (FLT3-ITD) and THP-1 (FLT3-WT), two normal karyotype primary AML samples (AML15, AML16), both with FLT3-WT, and fresh normal bone marrow cells. IC50 values were determined by exposing cell lines and bone marrow cells to BiQs for 72 h and 48 h, respectively. Each experiment was terminated with Alamar Blue (Sigma). Cell viability assays were carried out similarly except that the endpoint was trypan blue exclusion. For clonogenic assays, cells were plated in methylcellulose and exposed to BiQs either prior to plating or both prior to plating and during culture. Colonies were counted using an automated colony counter (Microbiology Intl.). Apoptosis was measured using the FITC Annexin V Kit (BD Pharmingen), and mitochondrial potential was assessed using the MitoRed Kit (Millipore); cells were analyzed by FACScan (BD Biosciences) and Flow Jo Software (Tree Flo). Standard Western blot techniques were used for measurement of caspase 3 and Nrf2 protein. Numbers are mean ± SD. Results The IC50 values (µM) of E6a for MOLM-14, THP1, AML15 and AML16 were 5.5 ± 0.8, 4.2 ± 1.9, 5.1, and 0.4, respectively. The IC50 values (µM) of B1a for MOLM-14, THP1, AML15 and AML16 were 6.2 ± 0.7, 5.6 ± 0.1, 5.4, and 3.0, respectively. The IC50 value of E6a for normal bone marrow cells was 14.5 µM. The mononaphthoquinone did not show anti-leukemic activity. Viability tests showed a 52 ± 8% and 33 ± 9% increase in MOLM-14 cell kill after exposure to 5 µM E6a and 5 µM B1a, compared to vehicle, versus 69 ± 12% and 59 ± 2% in THP-1. Treatment with E6a, compared to vehicle, resulted in a concentration-dependent decrease in colony formation in MOLM-14 (52 ± 17 [10 µM] vs 228 ± 170 [5 µM] vs 338 ± 72 colonies). Interestingly, when MOLM-14 cells were treated with E6a for 24 h then placed in methylcellulose in continuous presence of E6a for 9 days, colony formation was completely inhibited with 5 µM E6a compared to vehicle (2.5 ± 1 vs 294 ± 43 colonies). Treatment of AML16 with 5 µM E6a for 24 h resulted in a 1.5-fold increase in apoptosis, and a 1.6-fold increase in loss of mitochondrial membrane potential compared to vehicle. After 6 h exposure of MOLM-14 and AML16 to 5 µM E6a, cleavage of caspase 3 was detected. After 2 h exposure of AML16 to 5 µM E6a and 5 µM B1a, Nrf2 proteins was significantly increased in response to oxidative stress. Conclusions We have demonstrated that BiQs possess anti-leukemia activity with a reasonable therapeutic index in relation to normal bone marrow cells. Measurements of effects on intracellular ROS and on proteins involved in oxidative stress are ongoing, and drug transport by multidrug resistance-associated ATP-binding cassette proteins including P-glycoprotein will be studied. The more active BiQ will be studied further in an AML primagraft model. Disclosures: No relevant conflicts of interest to declare.

Description: Abstract 4799 Introduction Binaphthoquinones are unique molecules consisting of two linked naphthoquinone units. Previously, we regiospecifically synthesized a series of asymmetrical 2,2'-binaphthoquinones, which possess HIV integrase inhibitory activity. Potent activity against non-HIV-infected CEM-T4 acute lymphoblastic leukemia cells prompted us to investigate other cytotoxic mechanisms of these compounds. A genome-wide yeast screen uncovered that mitochondrial-related genes are required for sensitivity and resistance to these agents. Furthermore, by generating reactive oxygen species (ROS), biquinones halted yeast growth which was rescued by addition of N-acetylcysteine. Therefore, as part of our efforts to identify new compounds with anti-leukemic activity, we hypothesized that 2,2'-binaphthoquinones would be able to kill leukemic cells by interference with mitochondrial function. The majority of studies on antineoplastic effects of quinones have focused on benzoquinones, anthraquinones or monomeric naphthoquinones. However, nothing is published on the anti-leukemic action of asymmetrical 2,2'-binaphthoquinones, in which two different mononaphthoquinones are attached at the quinone double bond. Biquinones possess four carbonyl groups that have the potential to generate a greater number of ROS per one mole of quinone, and thereby cause more effective oxidative stress, than their monoquinone counterparts. In addition, the potential differences in cytotoxicities between monomeric and dimeric naphthoquinones result from many parameters, including the number of units, planarity, and the specific nature and pattern of aromatic functional groups. Materials and Methods Seventeen of our biquinones were dissolved in DMSO and incubated with four leukemia cell lines grown under standard conditions. All cultures were maintained with a constant DMSO concentration. A standard MTT cell proliferation assay was used to identify IC50 values. MV411 cells were incubated for 42-49 hours (2 nights) with two of the most potent compounds, biquinone #7 (BiQ7) and biquinone #10 (BiQ10), and they were assayed and analyzed by flow cytometry for loss of mitochondrial membrane potential (via rhodamine 123 staining), as well as a variety of apoptosis markers such as exposed phosphatidylserine, activated caspases, and sub-2n DNA increases. Simultaneously, preliminary toxicology experiments have been performed on mice. Results The IC50 values for both compounds were less than 5 micromolar (μM) against all four cell lines. For subsequent experiments, the cells were treated with either 5 μM BiQ7 or 5 μM BiQ10. A loss of mitochondrial membrane electrochemical potential, as expressed and evidenced by substantial decrease in fluorescence intensity of Rhodamine 123, was observed in 98-100% of the treated cells compared to control (5%). Loss of plasma membrane phosphatidylserine asymmetry was observed via Annexin V- PE (with 7AAD) staining in 94-95% of the treated cells and in only 18% of the control cells. Furthermore, the treated cells showed increases in staining for activated caspases 3 & 7 (BiQs 96-98%; control 10%). Finally, the cell cycle analyses via propidium iodide showed increases in sub-2n DNA in the treated cells compared to the control (control 12%; BiQ7 34%; and BiQ10 54%). Importantly, the preliminary toxicology results in mice suggest selectivity for neoplastic cells since no cytopenia or obvious end organ toxicity was observed with injection of 600 μM binaphthoquinones intraperitoneally daily for three weeks. Conclusion Our study shows that this new class of compounds possesses promising in vitro anti-leukemic effects by targeting mitochondrial membrane permeabilization, which occurs early in the apoptotic program and is located downstream of most identified chemotherapy resistance mechanisms in hematologic malignancies. In vivo experiments in xenograft model and ex vivo experiments on primary human cells are planned. Disclosures: No relevant conflicts of interest to declare.

Description: Introduction Despite recent advances in treatment, acute myeloid leukemia (AML) remains difficult to cure with high rates of relapse. Relapsed/refractory AML patients who are elderly or unfit for cytotoxic chemotherapy and whose disease fails to respond to hypomethylating agents represent an unmet need, and new safe and effective treatment options are needed for this patient population. Aspartate β-hydroxylase (ASPH) is a transmembrane protein that hydroxylates aspartyl and asparaginyl residues of epidermal growth factor (EGF)-like protein domains, and promotes cellular motility, migration, and adhesion. ASPH is highly expressed during fetal development and in placental trophoblasts, but not in any other healthy adult human tissue. ASPH is uniquely upregulated in cancer cells and is reported to be overexpressed in over 20 different solid neoplasms, in which it propagates a malignant phenotype, and is associated with increased cell proliferation, invasiveness, and poor prognosis. ASPH is therapeutically targetable via a fully human monoclonal antibody against ASPH, SNS-622. Subsequently, SNS-622 antibody-drug conjugates (ADCs) and a vaccine have been developed and are under current preclinical and clinical testing, respectively. We have previously demonstrated ASPH overexpression on the MOLM-14 AML cell line and effective in vitro killing of these cells using SNS-622 ADCs. In an effort to further characterize ASPH as a therapeutic target in AML, we report here the first study of ASPH expression patterns in AML patient samples. Methods Bone marrow (BM) aspirate and peripheral blood (PB) samples were collected from AML patients during 2014-2018 on a University of Maryland Greenebaum Comprehensive Cancer Center (UMGCCC) tissue banking protocol. Mononuclear cells were isolated by density centrifugation and were viably cryopreserved at -80ᵒC. Samples were analyzed using 8-color multiparameter flow cytometry to assess cell surface expression of ASPH, using fluorescein isothiocyanate (FITC)-conjugated SNS-622. The remainder of the fluorophores were labeled with standard lineage-specific markers. Expression of ASPH was measured via FITC fluorescence for each cell population and analyzed by two blinded, independent reviewers using FlowLogicTM software. Statistical analysis of ASPH expression was conducted using IBM® SPSS® Statistics for Windows, release 25.0.0 (IBM Corp., Armonk, N.Y., USA). Cohen's kappa (κ) was used to quantify the inter-observer agreement between two independent observers. Visual inspection of the expression data for the whole patient population showed a bimodal distribution, which was used to identify a robust cut-point separating high (i.e. positive) from low (i.e. negative) ASPH expression. Results Forty-two AML patient samples were evaluated (32 BM, 10 PB). Median patient age was 66 years, 48% (n=20) were female, 69% Caucasian and 21% African American. Disease status was 52% untreated de novo, 19% untreated secondary from antecedent MDS or MPN, and 29% relapsed/refractory. Samples were cytogenetically and molecularly diverse - with 50% exhibiting normal and 14% complex karyotype; 38% FLT3-ITD or FLT3-TKD, 29% NPM1, 19% IDH1/2, and 10% TP53 mutations. Full patient characteristics are shown in Table 1. Myeloblast expression of ASPH was found in 38% of samples (n=16; 14 BM, 2 PB) with a mean fluorescent intensity (MFI) of 10 as a cutoff for ASPH surface expression positivity. ASPH expression was not seen on other non-neoplastic cells including CD34+ hematopoietic stem cells, B- or T-lymphocytes, and monocytes. A blinded, independent review of the data revealed a Cohen's kappa (κ) of 0.74 with standard error of the estimate of ± 0.11. Patients with AML with ASPH expression were clinically heterogeneous, with no correlation between ASPH expression and AML subtype, karyotype or mutation status (Table 1). Conclusion ASPH is overexpressed in approximately 40% of patients with AML and serves as a promising therapeutic target. An ASPH nanoparticle vaccine is currently under clinical investigation and has shown promising results in solid tumors. We plan to expand clinical testing of targeting ASPH to AML. The ASPH positivity cutoff established via this work will serve as the eligibility criterion for the planned phase Ib/IIa of anti-ASPH vaccination in AML. . Disclosures Lebowitz: Sensei Biotherapeutics: Employment. Malhotra:Sensei Biotherapeutics: Employment. Fuller:Sensei Biotherapeutics: Employment. Shahlaee:Sensei Biotherapeutics: Equity Ownership; Sensei Biotherapeutics: Consultancy. Ghanbari:Sensei Biotherapeutics: Employment; Sensei Biotherapeutics: Equity Ownership. Emadi:NewLink Genetics: Research Funding.

Description: Introduction Presence of FLT3-ITD gene mutations is a poor prognostic factor in acute myeloid leukemia (AML). Midostaurin, a multikinase inhibitor, is approved for treatment of patients with newly diagnosed FLT3 mutant AML, in combination with cytarabine and daunorubicin standard chemotherapy. Midostaurin is not indicated as a single-agent induction therapy for AML treatment. Newer FLT3 inhibitors such as Quizartinib, Crenolanib and Gilteritinib have shown promising single agent activity in clinical trials involving patients with relapsed or refractory FLT3-mutated AML. Unfortunately, initial responses to FLT3 inhibitors are not durable, and leukemia progresses in virtually all patients. While several mechanisms of resistance to FLT3 inhibitors have been proposed, occurrence of new tyrosine kinase domain (TKD) mutations are among the most frequent and important mechanisms of resistance to current FLT3 inhibitors, making the development of novel FLT3 inhibitors imperative. F691, D835, and N676 are the most common mutations occurring in the kinase domain of the FLT3 protein; these confer resistance to currently available FLT3 inhibitors. We have synthesized a novel and selective FLT3 inhibitor, KRX-101 (a 4-substituted aminoisoquinoline), that has shown a superior anti-AML activity compared to available FLT3 inhibitors in vitro and in vivo. Importantly, KRX-101 possesses favorable pharmaceutical properties and has potent activity against the D835 and F691 mutations that arise during treatment with Quizartinib and Gilteritinib. Methods Using commercially available starting materials, the aminoisoquinoline compound was synthesized via a Sonogashira reaction. For enzymatic activity, KRX-101 and other FLT3 inhibitors were evaluated in protein based assays targeting FLT3-ITD including those with D835Y and F691L mutations (Reaction Biology, Malvern, PA; Eurofins DiscoveryX, Fremont, CA). In anti-proliferative assays, AML cell lines were exposed to KRX-101 and other FLT3 inhibitors for 72h in a 96-well plate. Assays were terminated with an MTT-like agent. IC50s were determined by GraphPad Prism. In pharmacokinetic assays, KRX-101 was administered to female rats (n=6) intravenously (IV, single dose, 5 mg/kg) or by oral gavage (single dose, 50 mg/kg). Blood was drawn at specific time points and plasma was isolated. The plasma concentrations of KRX-101 were determined by liquid chromatography mass spectrometry at Metabolite Profiling Facility, Bindley Bioscience Center, Purdue University. For in vivo efficacy studies, 1x106 MV4-11 cells expressing firefly luciferase were injected IV into female NSG mice. Three days later, mice were sorted into groups so that baseline luminescence (ie, disease burden) was equivalent and dosing started. Mice were imaged weekly. Results KRX-101 was synthesized with overall yield of 54% and has been scaled up for pharmaceutical development. KRX-101 in enzymatic activity assays inhibited FLT3-ITD at 2.3 nM (IC50) and FLT3-D835Y at 1.8 nM (IC50). In in vitro anti-proliferative assays, KRX-101 demonstrated robust activity in all tested AML cell lines harboring FLT3 mutations ranging from 0.07 to 7 nM (Table 1). KRX-101 showed similar or superior anti-AML activity in vitro compared to other FLT3 inhibitors. KRX-101 was readily orally bioavailable in rats. Twenty four hours after oral gavage, the plasma concentration of KRX-101 was 〉10 µg/mL (〉18 µM); 1000 fold higher than in vitro IC50s suggesting that three times weekly dosing is reasonable. In a head to head comparative study, KRX-101 appeared to be superior to Gilteritinib in a FLT3-ITD AML orthotopic model (Fig. 1A) by inducing undetectable disease at Day 22. Additionally, two mice whose disease progressed on Gilteritinib responded to KRX-101 (Fig. 1B). In another study, animals with clearly detectable FLT3-ITD AML were treated with aminoisoquinoline for 44 days. In the absence of detectable AML at day 44, treatment was discontinued. Mice were then monitored until day 175; 4 of 5 mice (80%) had no measurable disease. In all studies, KRX-101 dosed daily or thrice weekly was tolerated well. Conclusion KRX-101 is a novel agent with promising activity in FLT3 inhibitor-resistant AML. Testing in other FLT3 inhibitor-resistant animal models with various tyrosine kinase domain mutations is ongoing. Investigational New Drug (IND) enabling studies are underway. The Phase I clinical trial is planned. . Disclosures Sintim: KinaRx, LLC: Other: Founder and Scientific Advisor. Aman:KinaRx, LLC: Other: Founder. Holtsberg:KinaRx, LLC: Other: Founder. Emadi:NewLink Genetics: Research Funding. Lapidus:KinaRx, LLC: Other: Founder and Scientific Advisor.

Description: Background: Cytokine release syndrome (CRS) management in acute myeloid leukemia (AML) patients treated with flotetuzumab, an investigational CD123xCD3 bispecific DART® molecule for T cell redirected therapy. CRS is a hallmark of T cell activating therapy and can be correlated with efficacy, specifically, with CAR-T cells(1). Identification of patients at risk for high grade CRS will help guide CRS management. Flotetuzumab (MGD006) is anovel CD123xCD3 bispecific DART® molecule in Phase 1/2 testing in patients with relapsed/ refractory AML. Several strategies have been successfully employed to mitigate CRS severity, some have been previously reported (2, 3). Here we report on further refinement of CRS management and subsequent investigation of potentiel predictive biomarkers of severity. Methods: The recommended phase 2 dose (RP2D) of flotetuzumab is 500ng/kg/d CIV. Week 1 comprises a step-wise lead-in dose (LID) (1-step: 100 ng/kg/day days 1-4; 2-step: 30ng/kg/d for 3days, 100ng/kg/d for 4days, or multi-step (MS) LID at 30, 60, 100, 200, 300, 400 and 500 ng/kg/day each for 24 hours) in order to improve flotetuzumab tolerability. Tocilizumab usage recommended early in CRS management. The relationships between immune cells (T-cell subsets, monocytes) and tumor burden (percent CD123+ AML blasts, CD123 expression) were further interrogated as potential determinants of CRS. Results: 50 patients have been treated at the RP2D. While almost all patients experienced IRR/CRS events, the majority of these patients experienced IRR/CRS that were mild-moderate in severity (28% Grade(G)1, 62% G2, and 8% G3), of short duration (median 1 day for G1, 2 days G2, 2.5 days G3), and resolved completely with no clinical sequalae reported. Most CRS events occured in the first week of treatment (38.3%) and gradually decreased with continuous dosing (24.8%, 7.4%, and 4.3% during weeks 2-4, respectively). Several key interventions have helped mitigate CRS severity. Sequential increment in steps of LID schedules (1 step, 2-step or multi-step LID) have successfully decreased CRS severity and incidence. For example, CRS mean grade±SEM for week 1 was 2.0±0.26 vs 1.4±0.72 vs 1.5±0.63 and for week 4, 0.67±0.42 vs 0.2 ±0.50 vs 0.1 ±0.50 (1 step, 2-step or multi-step LID, respectively). Moreover, LID improved overall tolerability. Introduction of early use of tocilizumab has helped forestall CRS development; 27 patients received tocilizumab (10 doses for G1, 27 for G2, and 2 for G3 events), only 5 pts have required steroids (4 for G2 and 1 for G3), and no pts have required vasopressor support. Blunting of CRS events did not impact antileukemic activity. CRS severity showed a relationship with baseline frequency of circulating CD4+ cells (mean 0.2 K/µL in patients with no CRS vs. 1.0 K/µL in G1 vs 1.6 K/µL in G ≥2, p 〈 0.000.1), and peak CRS grade in week 1. Conclusion: Like other T-cell activating therapies, flotetuzumab is associated with CRS. Several mitigating factors have helped to blunt the severity of CRS, including lead-in dosing and early tocilizumab usage. Circulating CD4+ cells at baseline continues to be associated with CRS risk, and may be a helpful marker to identify patients at increased risk for CRS. 1. Maude, SL. et al. Managing Cytokine Release Syndrome Associated With Novel T Cell-Engaging Therapies. Cancer J. 2014; 20(2): 119-122. 2. Jacobs, K, et al.Lead-in Dose Optimization to Mitigate Cytokine Release Syndrome in AML and MDS Patients Treated with Flotetuzumab, a CD123 x CD3 Dart® Molecule for T-Cell Redirected Therapy. Blood 2017 130:3856. 3. Jacobs, K, et al.Management of Cytokine Release Syndrome in AML Patients Treated with Flotetuzumab, a CD123 x CD3 Bispecific Dart® Molecule for T-Cell Redirected Therapy. Blood 2018 132:2738. Disclosures Bakkacha: Macrogenics,Inc: Employment, Equity Ownership. Uy:Astellas: Consultancy; Pfizer: Consultancy; Curis: Consultancy; GlycoMimetics: Consultancy. Aldoss:Helocyte: Consultancy, Honoraria, Other: travel/accommodation/expenses; AUTO1: Consultancy; Jazz Pharmaceuticals: Honoraria, Other: travel/accommodation/expenses, Speakers Bureau; Agios: Consultancy, Honoraria. Foster:Bellicum Pharmaceuticals, Inc: Research Funding; Daiichi Sankyo: Consultancy; MacroGenics: Research Funding; Celgene: Research Funding. Sallman:Celyad: Membership on an entity's Board of Directors or advisory committees. Sweet:Pfizer: Consultancy; Incyte: Research Funding; Agios: Membership on an entity's Board of Directors or advisory committees; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Celgene: Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Stemline: Consultancy; Jazz: Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees. Rizzieri:Celgene, Gilead, Seattle Genetics, Stemline: Other: Speaker; AbbVie, Agios, AROG, Bayer, Celgene, Gilead, Jazz, Novartis, Pfizer, Sanofi, Seattle Genetics, Stemline, Teva: Other: Advisory Board; AROG, Bayer, Celgene, Celltron, Mustang, Pfizer, Seattle Genetics, Stemline: Consultancy; Stemline: Research Funding. Advani:Glycomimetics: Consultancy, Research Funding; Kite Pharmaceuticals: Consultancy; Amgen: Research Funding; Pfizer: Honoraria, Research Funding; Macrogenics: Research Funding; Abbvie: Research Funding. Emadi:Genentech: Consultancy, Honoraria; KinaRx: Membership on an entity's Board of Directors or advisory committees, Other: Co-Founder and Scientific Advisor, Patents & Royalties; NewLink Genetics: Research Funding; Jazz Pharmaceuticals: Research Funding; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Wieduwilt:Reata Pharmaceuticals: Equity Ownership; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Amgen, Leadiant, Merck, Servier: Research Funding. Vey:Novartis: Consultancy, Honoraria; Janssen: Honoraria. Arellano:Gilead: Consultancy. Löwenberg:Up-to-Date", section editor leukemia: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Agios Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Astex: Membership on an entity's Board of Directors or advisory committees; Chairman, Leukemia Cooperative Trial Group HOVON (Netherlands: Membership on an entity's Board of Directors or advisory committees; Clear Creek Bio Ltd: Consultancy, Honoraria; Editorial Board "European Oncology & Haematology": Membership on an entity's Board of Directors or advisory committees; Elected member, Royal Academy of Sciences and Arts, The Netherlands: Membership on an entity's Board of Directors or advisory committees; Frame Pharmaceuticals: Equity Ownership; Hoffman-La Roche Ltd: Membership on an entity's Board of Directors or advisory committees; Royal Academy of Sciences and Arts, The Netherlands: Membership on an entity's Board of Directors or advisory committees; Supervisory Board, National Comprehensive Cancer Center (IKNL), Netherland: Membership on an entity's Board of Directors or advisory committees; Chairman Scientific Committee and Member Executive Committee, European School of Hematology (ESH, Paris, France): Membership on an entity's Board of Directors or advisory committees; CELYAD: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees. Ravandi:Cyclacel LTD: Research Funding; Menarini Ricerche: Research Funding; Selvita: Research Funding; Xencor: Consultancy, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Macrogenix: Consultancy, Research Funding. Tran:MacroGenics: Employment. Muth:MacroGenics, Inc.: Employment, Equity Ownership. Baughman:MacroGenics, Inc.: Employment, Equity Ownership. Timmeny:MacroGenics, Inc.: Employment, Other: Stock Ownership. Topp:Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Regeneron Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Boehringer Ingelheim: Membership on an entity's Board of Directors or advisory committees, Research Funding; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Guo:Macrogenics: Employment. Zhao:MacroGenics, Inc.: Employment. Wigginton:macrogenics: Employment, Equity Ownership; western oncolytics: Consultancy, Other: consultancy. Bonvini:MacroGenics, Inc.: Employment, Equity Ownership. Walter:Daiichi Sankyo: Consultancy; Amgen: Consultancy; Agios: Consultancy; Boston Biomedical: Consultancy; Covagen: Consultancy; Amphivena Therapeutics: Consultancy, Equity Ownership; Aptevo Therapeutics: Consultancy, Research Funding; Argenx BVBA: Consultancy; Astellas: Consultancy; BioLineRx: Consultancy; BiVictriX: Consultancy; Boehringer Ingelheim: Consultancy; Pfizer: Consultancy, Research Funding; Race Oncology: Consultancy; Seattle Genetics: Research Funding; Jazz Pharmaceuticals: Consultancy; Kite Pharma: Consultancy; New Link Genetics: Consultancy. Davidson:Macrogenics,Inc: Employment, Equity Ownership. DiPersio:Incyte: Consultancy, Research Funding; Celgene: Consultancy; Karyopharm Therapeutics: Consultancy; Bioline Rx: Research Funding, Speakers Bureau; RiverVest Venture Partners Arch Oncology: Consultancy, Membership on an entity's Board of Directors or advisory committees; Cellworks Group, Inc.: Membership on an entity's Board of Directors or advisory committees; Magenta Therapeutics: Equity Ownership; WUGEN: Equity Ownership, Patents & Royalties, Research Funding; Amphivena Therapeutics: Consultancy, Research Funding; NeoImmune Tech: Research Funding; Macrogenics: Research Funding, Speakers Bureau. Jacobs:Macrogenics,Inc: Employment, Equity Ownership.