ALBERT

Description: Regulated vascular endothelial growth factor (VEGF) signaling is required for proper angiogenesis, and excess VEGF signaling results in aberrantly formed vessels that do not function properly. Tumor endothelial cells have excess centrosomes and are aneuploid, properties that probably contribute to the morphologic and functional abnormalities of tumor vessels. We hypothesized that endothelial cell centrosome number is regulated by signaling via angiogenic factors, such as VEGF. We found that endothelial cells in developing vessels exposed to elevated VEGF signaling display centrosome overduplication. Signaling from VEGF, through either MEK/ERK or AKT to cyclin E/Cdk2, is amplified in association with centrosome overduplication, and blockade of relevant pathway components rescued the centrosome overduplication defect. Endothelial cells exposed to elevated FGF also had excess centrosomes, suggesting that multiple angiogenic factors regulate centrosome number. Endothelial cells with excess centrosomes survived and formed aberrant spindles at mitosis. Developing vessels exposed to elevated VEGF signaling also exhibited increased aneuploidy of endothelial cells, which is associated with cellular dysfunction. These results provide the first link between VEGF signaling and regulation of the centrosome duplication cycle, and suggest that endothelial cell centrosome overduplication contributes to aberrant angiogenesis in developing vessel networks exposed to excess angiogenic factors.

Description: Bone marrow (BM) fibrosis is a key pathomorphologic feature of patients (pts) with primary myelofibrosis (PMF) and the fibrotic phases of essential thrombocythemia (post-ET MF) and polycythemia vera (post-PV MF). The degree of BM fibrosis appears to correlate with survival. Indeed worse survival has been associated with increased BM fibrosis. The BM stromal microenvironment is important in the pathogenesis of BM fibrosis. Cellular components (fibroblasts, macrophages, endothelial cells, adipocytes), structural fibrils (collagen, reticulin) and extracellular matrix components are all forming elements of the BM stroma. Increased stromal fibrosis has been linked to abnormalities in the number/ function of megakaryocytes and platelets in hematologic diseases. Several cytokines like Platelet Derived Growth Factor (PDGF) and Transforming Growth Factor-Beta (TGF-b) have been also linked to the pathophysiology of BM fibrosis. PDGF has been shown to increase fibroblast growth in megakaryocytes and platelets although increased PDGF did not correlate with increased production of either reticulin or collagenous fibrosis. Moreover, PMF pts have increased TGF-b levels in platelets, megakaryocytes, and monocytes. Nitric Oxide (NO) is a ubiquitous gas important in physiologic processes particularly vasodilatation. Dysregulation of NO levels has been implicated in pulmonary hypertension (PH), hemoglobinopathies, and cardiovascular diseases. In Peyronie’s disease, a localized fibrosis of the penile tunica albuginea, increased NO production by expression of iNOS decreases collagen deposition by neutralization of profibrotic reactive oxygen species and decreased myofibroblast formation. Aside from its role in maintaining normal vascular tone, NO also plays a role in fibroblast formation and collagen biosynthesis. We previously reported that ruxolitinib, a JAK1/2 inhibitor restores NO levels leading to improvement of PH in MF pts (Tabarroki et al., Leukemia 2014). We now hypothesize that plasma/serum NO level is a key regulator of BM fibrosis in MF and that ruxolitinib treatment (Tx) leads to improvement of BM fibrosis by NO modulation. Using a Sievers 280i NO analyzer we measured the plasma/serum NO level of a large cohort (n=75) of pts with myeloid and myeloproliferative neoplasms (MPN) [MDS, RARS/RCMD=8; MPN, ET=8, PV=8, MF=24, Mastocytosis=7; MDS/MPN, CMML=11, MDS/MPN-U, RARS-T=9]. Healthy subjects (n=10) were used as a control. MPN pts had low NO (nM) levels among the pts studied with the lowest level found in MF pts: MF=30.31±11.8, PV=39.0±16.1, ET=36±20.3, RARS=74.6±41.7 (P=.01), CMML=84.4±89.2 (P=.04), RCMD=163.4±103.8 (P

Description: Key Points Heme-bound iron activates placenta growth factor expression in erythroid cells via EKLF, a crucial erythroid-specific transcription factor. Markers of iron burden predict mortality in adults with sickle cell disease.

Description: Introduction Essential thrombocytosis (ET), polycythemia vera (PV), and myelofibrosis (MF) share the JAK2V617F mutation, but differ with regard to clinical phenotype, rate of disease progression, and risk of leukemic transformation. Variation in the JAK2V617F neutrophil allele burden does not account for these observed differences in clinical behavior. We therefore investigated JAK2V617Fallele burden and genotype in the stem/progenitor populations of MPN patients in chronic and leukemic phases. Methods We studied 39 JAK2V617Fpositive MPN patients evaluated between 2005 and 2013, including 8 patients at leukemic transformation. CD34+ cells isolated from peripheral blood were flow sorted based on CD34, CD38, and the stem cell marker aldehyde dehydrogenase (ALDH). JAK2V617F allele percentages were calculated using an allele specific real time PCR assay. Cells were sorted into 96 well plates and single cell JAK2V617Fgenotypes were obtained using a nested PCR assay. Additional genomic lesions and chromosomal copy number variation were investigated in the sorted fractions when applicable. Results In all MPN cases, the JAK2V617F mutation was detected in the CD34+CD38-ALDHhigh fraction – the same population in which the normal hematopoietic stem cell resides. Quantitative JAK2V617F allele burdens in this fraction were highest in MF 〉 PV 〉 ET. Single cell JAK2V617F genotyping revealed a higher proportion of JAK2V617F-/- cells in ET and PV than in MF, but JAK2V617F-/- cells were detectable in the CD34+CD38-ALDHhigh fraction of all cases. In most cases of PV and MF, this fraction contained a mixture of JAK2V617F-/-, JAK2V617F-/+, and JAK2V617F+/+ cells. Additional chronic phase lesions (including mutations of ASXL1 & TET2) were also found in the CD34+CD38-ALDHhighfraction. Two patterns of leukemic transformation were observed. The first pattern (in 7/8 patients) was identical to that of de novo AML (Gerber JM, Blood 2012), with emergence of a unique CD34+CD38-ALDHint fraction, which was clonal by JAK2V617F genotype and contained leukemia-specific lesions (e.g., 5q deletion). In contrast, the residual CD34+CD38-ALDHhigh population lacked the leukemic abnormalities and was oligoclonal with respect to JAK2V617F. In 3 of these AML cases, the CD34+CD38-ALDHint fraction was JAK2V617F-/-, while the JAK2V617F mutation remained detectable in the CD34+CD38-ALDHhigh fraction. Single cell genotyping performed during the leukemic phase of a PV patient revealed only JAK2V617F-/- CD34+CD38-ALDHint cells but identified JAK2V617F-/-, JAK2V617F-/+, and JAK2V617F+/+ CD34+CD38-ALDHhigh cells; JAK2V617F levels were barely detectable in the progenitors and neutrophils during this leukemic phase. Upon achievement of complete remission from AML, high JAK2V617F allele burdens were then found in the progenitors and neutrophils, as well as in the CD34+CD38-ALDHhigh fraction. A second pattern of leukemic transformation was seen in one patient, in whom no CD34+CD38-ALDHint population was present. The CD34+CD38-ALDHhigh population was expanded in this case and harbored JAK2V617F+/+ positive cells with the leukemia-specific lesion. Conclusions Unlike CML, in which the BCR/ABL oncogene is typically present in the majority of CD34+CD38-ALDHhigh cells at diagnosis (Gerber JM, Am J Hematol 2011), the JAK2V617F mutation was present in only a minority of CD34+CD38-ALDHhigh cells in JAK2V617F positive ET and PV. Moreover JAK2V617F-/- cells were detected even in longstanding, advanced phase PV and MF. Lower JAK2V617F clonal burdens in the primitive CD34+CD38-ALDHhigh compartment as compared to neutrophils in most cases of MPN suggest that the JAK2V617F mutation does not confer a significant advantage at the stem cell level and that other genetic lesions may drive expansion of this population. JAK2V617F negative leukemias occur in about 35% of PV patients, apparently arising from the residual JAK2V617F negative CD34+CD38-ALDHhigh reservoir. We conclude that primitive stem/progenitor cells are mosaic with regard to JAK2V617F mutation status in the majority of MPN patients. Furthermore, acquisition of JAK2V617F, development of JAK2V617F homozygosity, and accrual of other acquired lesions in chronic phase MPN all occur in the primitive CD34+CD38-ALDHhigh compartment. Lesions specific to post MPN AML segregate to a distinct CD34+CD38-ALDHint population. Disclosures: Jones: Cytomedix: Patent holder for Aldefluor reagent, which is licensed by Cytomedix. This relationship is managed by the Johns Hopkins Office of Policy Coordination., Patent holder for Aldefluor reagent, which is licensed by Cytomedix. This relationship is managed by the Johns Hopkins Office of Policy Coordination. Patents & Royalties.

Description: Isochromosome 17q [i(17q)], a poor prognostic cytogenetic abnormality is a product of the breakage or inappropriate division of the pericentromere leading to the duplication of the long and loss of the short arm of chromosome 17. The region of the breakpoints maps at 17p11, a region encompassing a key tumor suppressor gene: TP53. I(17q) are detected in myelodysplastic/ myeloproliferative neoplasms (MDS/ MPN), chronic myeloid leukemia (CML), and acute myeloid leukemia (AML). This abnormality can occur as a sole structural abnormality or in combination with other chromosomal defects. The presence of i(17q) is associated with poor therapeutic response, disease progression, and an unfavorable clinical outcome. Elucidation of the molecular architecture of patients (pts) carrying i(17q) may lead to better understanding of disease biology and development of novel compounds that can target this disease. We selected 11 pts with i(17q) to characterize their genomic differences. We applied whole exome sequencing (WES) in order to define latent molecular defects explaining the clinical phenotype of this disease. The index case was a male MDS/MPN pt with isolated i(17q), 27% RS, hypercellular bone marrow (BM), mild splenomegaly, and atypical megakaryocytes. The pt developed 7% BM blasts without clinical response to growth factors. Molecularly this pt was a wild type SF3B1, a gene frequently mutated in RARS-T and associated with lower transformation rate to leukemia, better survival, and good/intermediate risk cytogenetic abnormalities. WES was performed on 2 ug of total DNA extracted from BM cells. Non-clonal CD3+ cells were used as source of germ-line control. Twenty-millions reads were run on an Illumina HiSeq2000 sequencer. Using a stringent bio-informatic algorithm developed in house, all variants were filtered based on a variation score (〉=30) and a coverage (30X) and the tumor nucleotide variation analysis was performed for each pair (tumor vs. germ-line), where only the variants unique to the tumor were retained. Variants were ultimately filtered in order to exclude SNPs by an in-house annotation and importing the hg19 SNP135. We detected 65 unique candidate genes. Four genes were confirmed to be somatic: 3 were novel: ZFP42 (4q35.2), P4HTM (3p21.31), and VPRBP (3p21.2) and 1 includes the newly discovered SETBP1 (18q12.3) gene. Three variants detected on the chromosome 17 had a wild type configuration. The subsequently genotyped all the pts (MDS/MPN/-U 3; AML 4; RCMD 1; CML 1; RAEB-1 2; mean age: 68 years; male/female: 8/3; i(17q)/other abnormalities:3/8) for the above genes and for a panel of genes known to be mutated in MDS/MPN and other diseases in order to find any genetic association explaining the disase phenotype. We applied Sanger sequencing to DNA derived from BM/peripheral blood cells (BM/PB:7/4) for the following genes and respective exons: TP53 (all exons), SF3B1 (13-16), SRSF2 (1-2), U2AF1 (2 and 6), TET2 (all exons), DNMT3A (18-23), IDH1/2 (4), CBL (8-9), N/KRAS (1-2), ASXL1 (12), JAK2 (12 and 14), EZH2 (16, 18 and 19), MPL (exon 10), BCAS3 (12, 15 and 16), FLT3 (11 and 17), and CSF3R (13,14, and 17). In total, we found 16 heterozygous missense mutations and 1 tandem duplication. We found somatic mutations in ZFP42, P4HTM, and VPRBP in 1 pt. The index case reported a mutation in SETBP1 and SRSF2. SF3B1 was detected as a sole abnormality in 1 patient. Of note, the patient with SF3B1 mutation (K700E) had 50% RS and achieved a complete hematologic remission after decitabine therapy. The most frequent mutations were found in SETBP1 and SRSF2. SETBP1 was found to be mutated in 4/11 (36.3%) pts (D868N, I871T, and G870S was common in 2 pts) while SRSF2 mutations (P95H/R) were found in 3/11 (27.2%) pts. Three pts showed concomitant SRSF2 and SETBP1 mutations. NRAS (G12D) was mutated in 1 pt and associated with SRSF2 and SETBP1 mutations. One pt showed mutations in TET2, JAK2, and TP53. Of note, this pt did not respond to treatment. One pt with MDS/MPN showed a mutation in CSF3R (Q741X), a novel gene discovered in chronic neutrophilic leukemia and atypical CML. The pt also has monosomy 7 and i(17q) abnormality. FLT3-ITD was found in 1 pt. As of last follow-up, only 2 pts remain alive. In sum, we found that poor risk molecular mutations in SRSF2 and SETBP1 are frequently found in i(17q) myeloid malignancies and may be the drivers of poor outcomes in this disease. Disclosures: No relevant conflicts of interest to declare.

Description: We hypothesized that the silent cerebral infarcts (SCI), which affect up to 40% of children with sickle cell disease (SCD), could occur in the setting of acute anemic events. In a prospective observational study of children with and without SCD hospitalized for an illness associated with acute anemia, we identified acute silent cerebral ischemic events (ASCIE) in 4 (18.2%) of 22 with SCD and in 2 (6.7%) of 30 without SCD, using diffusion-weighted magnetic resonance imaging. Children with ASCIE had lower hemoglobin concentration than those without (median 3.1 vs 4.4 g/dL, P = .003). The unique temporal features of stroke on diffusion-weighted magnetic resonance imaging permit estimation of incidence rates for ASCIE of 421 (95% confidence interval, 155-920) per 100 patient-years during acute anemic events for all patients. For children with SCD, the estimated incidence was 663 (95% confidence interval, 182-1707) which is much higher than previously reported. Acute anemic events are common in children with SCD and prevalence could partially account for the high SCI. Some ASCIE (1 of 4 in our study) may be reversible. Alterations in management may be warranted for children with severe anemia to identify unrecognized ischemic brain injury that may have permanent neurocognitive sequelae.

Description: A key feature differentiating nonpathogenic SIV infection of sooty mangabeys (SMs) from pathogenic HIV/SIV infections is the rapid resolution of type I IFN (IFN-I) responses and IFN-stimulated gene expression during the acute-to-chronic phase transition and the establishment of an immune quiescent state that persists throughout the chronic infection. We hypothesized that low levels of IFN-I signaling may help to prevent chronic immune activation and disease progression in SIV-infected SMs. To assess the effects of IFN-I signaling in this setting, in the present study, we administered recombinant rhesus macaque IFNα2-IgFc (rmIFNα2) to 8 naturally SIV-infected SMs weekly for 16 weeks. Gene-expression profiling revealed a strong up-regulation of IFN-stimulated genes in the blood of treated animals, confirming the reagent's bioactivity. Interestingly, we observed an approximately 1-log decrease in viral load that persisted through day 35 of treatment. Flow cytometric analysis of lymphocytes in the blood, lymph nodes, and rectal biopsies did not reveal a significant decline of CD4+ T cells, a robust increase in lymphocyte activation, or change in the level of SIV-specific CD8+ T cells. The results of the present study indicate that administration of type I IFNs in SIV-infected SMs induces a significant anti-viral effect that is not associated with a detectable increase in chronic immune activation.

Description: Introduction Treatment of sickle cell disease (SCD) has often required the use of opioids for the treatment of pain. While guidelines for specific medications and dosing are available for inpatient and emergency department use, less is known about the outpatient treatment of adult SCD patients. The aim of this study is to evaluate the role of outpatient opioids in adults with sickle cell disease. Method The Adult Hemoglobinopathy Resource Center at Washington University provides care for adult SCD patients throughout the St. Louis, Missouri metropolitan area. All patients have confirmed SCD (Hgb SS, Hgb SC, Hgb Sβ+, Hgb Sβ0, Hgb SOther) and have been seen at least once since 2011 to be included in the study. Patients were considered to be compliant with their outpatient care if they were seen at least once per year and did not miss more than three consecutive appointments. The type of opioid that was used was determined based on the most recent filled prescription. Patients were considered to be on chronic opioids if they received 〉1 prescription/month or were over a 3 month period. Patients were considered to be on no opioids if they received ≤1 prescription in 3 months. Results Three hundred and seventeen patients have been evaluated between January 2011 and June 2013 of which 9 (2.8%) have died during that time period. Of the surviving patients, 33 (10.7%) have not been actively followed (poor compliance/disruptive behavior-29, incarcerated-2, moved out of town-1, transfer of care-1). Of the patients actively followed, the mean age is 32 years (range 17-72); 148 patients (53.8%) are female and 127 (46.2%) are male. The hemoglobinopathies include SS-175, SC-80, Sβ+-14, Sβ0-5, SCHarlem-1. Long-term red cell transfusions were performed in 25 patients (automated RBC exchange-13, partial manual exchange-8 and simple transfusions-4) and hydroxyurea was prescribed in 101 patients (Hgb SS-92 patients). At present, 151 patients (54.9%) are prescribed chronic long and short acting opioids and 76 patients (27.6%) are on chronic short acting opioids with a much smaller number of patients (40 pts) not receiving opioids. Notably 18 of 40 patients not receiving opioids were effectively treated with either hydroxyurea or transfusion therapy. Of the 104 patients ≤25 years of age, 60 (57.7%) were on chronic long and short acting opioids at the time of their initial care. The most commonly prescribed long-acting opioid used was extended release morphine sulfate and the most common short acting opioid was oxycodone. Because of recent concerns about non-compliance and diversion, urine drug screens have been utilized with increasing frequency to assess opioid use and of the last 30 patients receiving long-acting therapy who were tested, 17 samples did not identify the prescribed medication suggesting some degree of opioid misuse. Conclusions While opioids have been an important adjunctive treatment for patients with sickle cell disease, their most effective use in adult patients is difficult to define. Strategies to decrease the use of opioids in the adolescent and young adult population along with disease-modifying therapy such as hydroxyurea and RBC transfusions would seem to be helpful to decrease the chronic use of opioids. Furthermore, chronic use of opioids is frequently associated with poor compliance. The use of urine drug screens may be helpful to improve compliance and decrease diversion. Disclosures: Blinder: Novartis Pharmaceuticals: Consultancy, Research Funding.

Description: Abstract 61 To identify new therapeutic strategies for AML, we compiled and screened an in-house library of on-patent and off-patent drugs to identify agents cytotoxic to leukemia cells. From this screen, we identified mefloquine, an off-patent drug indicated for the treatment and prophylaxis of malaria. In secondary assays, mefloquine decreased the viability of 9/10 human and murine leukemia cell lines (EC50 3.25–8.0 μM). Moreover, it reduced the viability of 4/5 primary AML samples, but was not cytotoxic to normal hematopoietic cells (EC50〉31 μM). Importantly, mefloquine reduced the clonogenic growth of primary AML samples, but not normal hematopoietic cells, and completely inhibited engraftment of primary AML cells into immune deficient mice. Finally, systemic treatment with oral mefloquine (50 mg/kg/day) decreased leukemic burden without evidence of toxicity in 4 mouse models of leukemia, including mice engrafted with primary AML cells. Thus, mefloquine effectively targets leukemic cells, including leukemia stem cells, at concentrations that appear pharmacologically achievable and are not toxic to normal hematopoietic cells. To identify the mechanisms of mefloquine-mediated cell death in AML cells, we performed a binary drug combination screen, hypothesizing that drugs that synergized with mefloquine may share overlapping mechanism of action. From this combination screen of 550 drugs, we identified 18 that reproducibly synergized with mefloquine as measured by the Excess over Bliss additivism score, including 3 members of the artemisinin class of anti-malarials: artemisinin, artesunate and artenimol. Strikingly, 10/18 synergistic compounds, including the artemisinins, were known generators of reactive oxygen species (ROS). Therefore we tested mefloquine's ability to increase ROS in leukemic cells. Mefloquine increased ROS production in leukemia cells in a dose- and time-dependent manner. Co-treatment with ROS scavengers α-tocopherol and N-acetyl-cysteine abrogated mefloquine-induced ROS production and cell death, indicating that ROS production was functionally important for mefloquine-mediated cell death. Moreover, the artemisinins induced ROS as single agents, and synergistically increased ROS when combined with mefloquine. To identify cellular target(s) of mefloquine's anti-leukemic effects, we performed a yeast genome-wide functional screen to identify heterozygous gene deletions that rendered yeast more sensitive to mefloquine. 21/37 genes whose depletion conferred 〉4-fold sensitivity to mefloquine were associated with function of the yeast vacuole, equivalent to the mammalian lysosome. Consistent with these data, fluorescent confocal microscopy demonstrated that mefloquine and artesunate disrupted lysosomes. Cell death after mefloquine and artesunate treatment was caspase-independent and associated with increased incorporation of monodancylcadaverin in autophagosomes, consistent with the effect of these drugs on the lysosomes. To further explore the anti-leukemic activity of lysosomal disruption, we evaluated the anti-leukemic effects of the known lysosomal disrupter L-leucine-leucine methyl ether (LeuLeuOMe). Similar to mefloquine and artesunate, LeuLeuOMe induced cell death in leukemia cells, increased ROS production, and disrupted the lysosomes. Highlighting the potential clinical utility of lysosomal disrupters for the treatment of leukemia, a patient with relapsed/refractory juvenile myelomonocytic leukemia self-administered artemisinin. The artemisinin cleared the circulating blasts from the circulating blasts and the patient proceeded to allotransplant. Finally, to investigate the basis of leukemic cell hypersensitivity to lysosomal disruption, we assessed lysosomal characteristics of primary AML and normal hematopoietic cells. By gene expression analysis, AML patient samples had higher mRNA levels of the lysosomal cathepsins A, B, C, D, H, L, S and Z, compared to CD34+ normal hematopoietic cells, and cathepsins C, D and Z were significantly over-expressed in the LSC compartment, compared to normal HSCs. In summary, our data demonstrate that lysosomal disruption preferentially targets AML cells and AML stem cells through a mechanism related to increased ROS production. Thus, this work highlights lysosomal disruption as a novel therapeutic strategy for AML. Disclosures: Off Label Use: This study includes a case report of off-label use of the anti-malarial artemisinin in the treatment of a case of juvenile myelomonocytic leukemia.