ALBERT

Description: Key Points Injured brain releases hyperadhesive and microvesicle-bound VWF that causes neurological dysfunction and a systemic hypercoagulable state. ADAMTS-13 protected the blood-brain barrier to prevent TBI-induced neurological dysfunction and systemic coagulopathy.

Description: Background:Waldenstrom's macroglobulinemia (WM) is one type of lymphoma that had the characteristic of both lymphocytes and plasma cells. Rituximab-based or bortezomib-based regiments are commonly used treatment approaches in routine practice in previously untreated patients with LPL/WM. However, which regiment is better still unknown. The purpose of this study is to compare the efficacy of RCD (Rituximab,cyclophosphamide and dexamethasone) and BCD (Bortezomib, cyclophosphamide and dexamethasone)in newly diagnosed WM patients. Methods:30 newly diagnosed WM patients were randomly assigned to BCD or RCD group for introduction chemotherapy. Chemotherapeutic response was evaluated after 3 cycles. If a minor response (MR) or better response achieves, addition 3 cycles will be given. If not, patients will be crossed to control group for another 3 cycles. If a MR or better response comes out, addition 3 cycles will be given, otherwise, the patients will quit this study. Results: Finally, 15 patients were assigned to each treatment group. The basic characteristics of the two groups were similar. The median time to response in RCD and BCD group were 4 months and 3 months, respectively. The CR rate in RCD and BCD group was 20% and 26.7% respectively, with VGPR rate 26.7% and 6.7%, PR rate 46.7% and 40% in each group respectively. Additional 20% minor response was observed in BCD group. The overall response was 86.7% in both groups. However, RCD group had higher good response rate (≥VGPR) compared to BCD ( 46.7% vs 33.4%, p=0.05). The rate of major response (≥PR) in RCD group was higher than that in BCD group (86.7% vs 66.7%, p=0.195). The median follow-up time was 29 months. The median duration of response in RCD and BCD group was 35 months and 30 months, respectively. The 3-year progression-free rate of RCD group was significantly higher than that of the BCD group (87.5% vs 39.2%,p=0.045). The 3-year overall survival rate was 100% with RCD group versus 70% with BCD group (100% vs 70%, p=0.127)The most common adverse events of any grade with RCD and BCD were hematological toxicity. 3 patients in the RCD group had grade 3 or higher granulocytopenia.4 patients in the BCD group occurred grade 3 or higher hypocytosis. Other adverse event in the RCD group included pneumonia (40%), non-infectious fever (26.7%), hyperglycemia (13.3%) and rash (6.7%).The most common non-hematological adverse event in BCD group were peripheral neuropathy (40%), pneumonia (26.7%), herpes zoster (13.3%) and ventosity(6.7%). Events of non-infectious fever occurred more frequently in the RCD group (26.7% vs 0%, p=0.032). However, peripheral neuropathy was more common in the BCD group (40% vs 6.7%, p=0.031). There was no serious non-hematological grade 3 or higher adverse events occurred in the both groups. Conclusion: The RCD and BCD regimens have similar overall response in newly diagnosed WM. RCD regimen has higher good response rate and longer PFS time compared to BCD regimen. Both regimens have good tolerance. Disclosures No relevant conflicts of interest to declare.

Description: Abstract 182 Chromosomal alterations are a hallmark of acute lymphoblastic leukemia (ALL), but many cases lack a recurring cytogenetic abnormality. To identify novel alterations contributing to leukemogenesis, we previously performed genome-wide profiling of genetic alterations in pediatric ALL using single nucleotide polymorphism (SNP) microarrays. This identified a novel focal deletion involving the pseudoautosomal region (PAR1) of Xp/Yp in 15 B-progenitor ALL cases lacking sentinel chromosomal abnormalities, including six of eight cases of ALL associated with Down syndrome (DS-ALL). The deletion involved hematopoietic cytokine receptor genes, including IL3RA and CSF2RA, but due to poor array coverage, it was not possible to define the limits of deletion using SNP array data alone. To characterize this abnormality, we examined an expanded cohort of 329 B-ALL cases, including 22 B-progenitor DS-ALL cases. Strikingly, 12 (55%) DS-ALL cases harbored the PAR1 deletion. Mapping using high density CGH arrays showed the deletion to be identical in each case, and involved a 320kb region extending from intron 1 of the purinergic receptor gene P2RY8 to the promoter of CRLF2 (encoding cytokine receptor like factor 2, or thymic stromal lymphopoietin receptor). The deletion resulted in a novel fusion of the first, non-coding exon of P2RY8 to the entire coding region of CRLF2 in each case. The P2RY8-CRLF2 fusion resulted in elevated expression of CRLF2 detectable by quantitative RT-PCR, and flow cytometric analysis of leukemic cells. One DS-ALL case with elevated CRLF2 expression lacked the PAR1 deletion, but had an IGH@-CRLF2 translocation detected by fluorescence in situ hybridization (FISH). CRLF2 alteration was associated with gain of chromosome X (which was shown by FISH to result in duplication of the PAR1 deletion), deletion of 9p, and the presence of Janus kinase (JAK1 and JAK2) mutations. Ten (53%) of patients with CRLF2 alteration had JAK mutations, compared with two patients lacking CRLF2 abnormalities (P

Description: In children with acute lymphoblastic leukemia (ALL), failure due to therapy-related myeloid leukemia (t-ML) is a devastating complication. Using a target gene approach, only a few host genetic risk factors for t-ML have been defined. Microarray analysis of gene expression allows for a more genome-wide approach to identify possible genetic risk factors for t-ML. We assessed gene expression profiles (12625 gene probe sets) using oligonucleotide-based arrays in diagnostic ALL blasts from 228 children treated on St. Jude ALL protocols (Total XIII) that included etoposide; 13 of these children developed t-ML. A group of 83 probe sets were significantly related to the time-dependent risk of t-ML, with principal component analysis plot (right panel) separating patients who developed t-ML from the others. Hierarchical clustering of the 83 probe sets grouped patients into 3 clusters (n=163, n=52, n=13), with the cumulative incidence of t-ML being significantly higher in the last cluster (p 〈 0.0001, left panel) compared to those of the other gene-expression-defined clusters. Figure Figure A permutation test indicated that probe sets selected by chance are unlikely to obtain the observed distinct clusters (p=0.045). Distinguishing genes included transcription-related oncogenes (v-Myb, Pax-5), cyclins (CCNG1, CCNG2 and CCND1) and Histone H4. Common transcription factor recognition elements among similarly up- or down-regulated genes included several involved in hematopoietic differentiation or leukemogenesis (Maz, PU.1, FOXO4). This approach has identified several genes whose expression differentiates patients at risk of t-ML, and provides targets for assessing the germline predisposition to leukemogenesis.

Description: Abstract 3509 Mutations in the isocitrate dehydrogenase 1 (IDH1) and 2 (IDH2) genes are present in ∼16% of acute myeloid leukemia, and cause a neomorphic enzyme activity that results in the production of 2-hydroxyglutarate (2HG). Mutational and epigenetic profiling of a large patient cohort of acute myeloid leukemia (AML) has revealed that IDH1/2-mutant AMLs display global DNA hypermethylation and an impaired hematopoietic differentiation. To further investigate the intrinsic effect of 2HG on hematopoietic proliferation and differentiation, we transfected an erythroleukemia cell line (TF-1) with either IDH1 or IDH2 mutant alleles. These cells overexpress the mutant enzyme, have high levels of 2HG, and exhibit GM-CSF independent growth. Consistent with clinical observations, overexpression of the IDH mutant proteins led to hypermethylation of both histones and DNA. These results suggest that mutations in IDH1/2 could lead to epigenetic rewiring of cells that could facilitate the gain of function phenotype. To gain a broader understanding of the biological consequence of the IDH1/2 gain of function mutations we have generated small molecules that are capable of selectively inhibiting IDHm enzymes. Upon compound treatment in vitro, we are able to reverse hypermethylation of both histones and DNA in Idhm expressing cells. These compounds are also suitable for use in vivo and upon compound treatment are able to lower 2HG by 〉90% in tumor xenograft models. These data suggest that an inhibitor of IDH1/2 mutations could correct the altered gene expression patterns seen in IDH1/2 mutant AML tumors and potentially lead to a profound effect on hematopoietic differentiation, proliferation and tumor growth. Disclosures: Yen: Agios Pharmaceuticals: Employment, Equity Ownership. Wang:Agios Pharmaceuticals: Employment, Equity Ownership. Schalm:Agios Pharmaceuticals: Employment, Equity Ownership. Hansen:Agios Pharmaceuticals: Employment, Equity Ownership. Straley:Agios Pharmaceuticals: Employment. Kernytsky:Agios Pharmaceuticals: Employment, Equity Ownership. Choe:Agios Pharmaceuticals: Employment, Equity Ownership. Liu:Agios Pharmaceuticals: Employment, Equity Ownership. Popovici-Muller:Agios Pharmaceuticals: Employment, Equity Ownership. Travins:Agios pharmaceuticals: Employment, Equity Ownership. Yang:Agios Pharmaceuticals: Employment, Equity Ownership. Silverman:Agios Pharmaceuticals: Employment, Equity Ownership. Gross:Agios Pharmaceuticals: Employment, Equity Ownership. Dang:Agios Pharmaceuticals: Employment, Equity Ownership. Salituro:Agios Pharmaceuticals: Consultancy, Equity Ownership. Saunders:Agios Pharmaceuticals: Consultancy, Equity Ownership. Dorsch:Agios Pharmaceuticals: Employment, Equity Ownership. Agresta:Agios Pharmaceuticals: Employment. Schenkein:Agios Pharmaceuticals: Employment, Equity Ownership. Su:Agios Pharmaceuticals: Employment, Equity Ownership. Biller:Agios Pharmaceuticals: Employment, Equity Ownership.

Description: Abstract 2856 Germline and somatic mutations (heterozygous) in Ptpn11 (Shp2), a protein tyrosine phosphatase implicated in multiple cell signaling processes, have been identified in juvenile myelomonocytic leukemia (JMML), a childhood myeloproliferative disease (MPD), and pediatric acute leukemias. These mutations cause hyperactivation of Shp2 catalytic activity and enhance the binding of mutant Shp2 to signaling partners. Ptpn11 mutations are sufficient to drive the development of JMML-like MPD and acute leukemias in mice, suggesting that they play a causal role in the pathogenesis of hematological malignancies. However, the mechanisms by which Ptpn11 mutations induce these malignancies are not completely understood and the signaling partners that mediate the pathogenic effects of Ptpn11 mutations have not been explored. We previously generated a line of conditional knock-in mice with Ptpn11E76K mutation, the most common and most active Ptpn11 mutation found in JMML and acute leukemias. Induced knock-in of this mutation in hematopoietic cells resulted in MPD with full penetrance as a result of aberrant activation of hematopoietic stem cells (HSCs) and myeloid progenitors (J. Exp. Med., 2011). Recently, we discovered that the interaction between Shp2 E76K and Gab2, a prominent interacting protein of Shp2 and a scaffolding protein important for cytokine-induced PI3K/Akt/mTOR signaling, was greatly enhanced, and that mTOR was highly activated in Ptpn11E76K/+ MPD cells. To address the role of Gab2 and mTOR in the pathogenesis of Ptpn11E76K/+ mutation-induced MPD, Ptpn11E76K/+/Gab2-/- double mutant mice were generated and their phenotypes were compared with those of Ptpn11E76K/+ single mutant mice. MPD phenotypes were markedly attenuated in Ptpn11E76K/+/Gab2-/- double mutant mice. Overproduction of myeloid cells in the bone marrow was alleviated, and splenomegaly was diminished in the double mutants. Myeloid cell infiltration in the liver also decreased. Cytokine (IL-3 and GM-CSF) sensitivity of myeloid progenitors was significantly decreased in Ptpn11E76K/+/Gab2−/− mice as compared to that in Ptpn11E76K/+ mice. Hyperactivation of HSCs and excessive myeloid differentiation caused by Ptpn11E76K mutation were largely corrected by deletion of Gab2. Furthermore, we treated Ptpn11E76K/+ mice with Rapmycin, a specific and potent mTOR inhibitor, which substantially diminished MPD phenotypes. Collectively, this study reveals the essential role of the Gab2/PI3K/mTOR pathway in mediating the pathogenic effects of Ptpn11E76K/+ mutation and suggests that Gab2 and mTOR are potential therapeutic targets for the treatment of Ptpn11-associated hematological malignancies. Disclosures: No relevant conflicts of interest to declare.

Description: The leukemic stem cell (LSC) depends on specific interactions with extracellular matrix, soluble factors, and cellular components of the microenvironment, or niche. These interactions promote LSC self-renewal and survival, thus contributing to chemoresistance and treatment failure. Understanding the signaling pathways that promote LSC maintenance in response to niche interactions may reveal novel targets for therapy. Recent studies indicate a critical role for the small Rho GTPase, Cdc42, in the maintenance of normal hematopoietic stem and progenitor cells (HSPCs). Cdc42 coordinates actin cytoskeleton organization, adhesion, migration, self-renewal, cell polarity, proliferation, and survival of normal HSPCs in response to niche signaling through multiple cell surface receptors, including CXCL12/CXCR4, SCF/KIT, and fibronectin/integrin. Cdc42 activity is increased in both murine and human models of MLL-AF9 (MA9) acute myeloid leukemia (AML). Cdc42 expression is also increased in human patient AML samples across cytogenetic subtypes, compared to normal hematopoietic cell subsets, in analysis of curated datasets in the HemaExplorer database. In earlier work, we have shown that Cdc42 inhibition leads to peripheral mobilization of leukemia cells out of the marrow niche (Blood 114, 13). In the present study, we investigate whether Cdc42 inhibition also disrupts intrinsic LSC self-renewal. To interrogate Cdc42 in LSC self-renewal, MA9 cell lines were established following transduction of bone marrow HSPCs harvested from tamoxifen-inducible Cdc42 knockout mice, with Cre null donors as controls. Upon tamoxifen (TAM) treatment, Cdc42KO-MA9 cells had decreased CFU and small, diffuse colony morphology. Mice transplanted with untreated MA9 cells were divided to receive injections of TAM vs control. The Cdc42KO-MA9 cohort remains alive at over 180 days post-transplant, whereas vehicle control mice died of AML with latency similar to Cre null MA9 cell recipients (p

Description: The acquired genetic characteristics of acute lymphoblastic leukemia (ALL) blasts are often used to guide the intensity of therapy, whereas the germline host genetic characteristics of the patient generally have not been considered. Multiple common, functionally important polymorphisms affect genes whose products determine the pharmacokinetics and pharmacodynamics of antileukemic agents. It is not yet known how genetic polymorphisms may interact to affect the outcome of antileukemic therapy. Combining classification and regression tree with failure time analysis, we assessed whether 16 genetic polymorphisms, alone or in combination, predicted relapses in 246 children with ALL, 116 of whom were treated on the lower-risk (LR) and130 on the higher-risk (HR) arms of the St Jude protocol Total XIIIB. Genotyping was performed for the following polymorphic loci: CYP3A4*1B and CYP3A5*3; GSTP1 313A〉G, GSTM1 and GSTT1 deletions; MDR1 exon 21 (2677G〉T/A) and MDR1 exon 26 (3435C〉T); MTHFR 677C〉T and MTHFR 1298A〉C; NR3C1 1088A〉G; SLC19A1 80G〉A; TPMT 238G〉C, 460G〉A and 719A〉G; TYMS enhancer repeat; UGT1A1 promoter repeat polymorphism; VDR intron 8 G〉A and VDR FokI (start-site) T〉C. In all children with available RNA in their diagnostic ALL blasts, gene expression levels of prognostic genotypes were analyzed using the Affymetrix genechip array HG_U95Av2. Among the HR group, the glutathione S-transferase M1 (GSTM1) non-null genotype was associated with the risk of hematological relapse (5-year cumulative incidence, 17.1%±4.5% compared to 5.1%±2.9% for GSTM1 null genotype, p = 0.03), and among the non-null genotypes, the thymidylate synthetase (TYMS) 3/3 genotype was associated with a further increase in hematologic relapse risk (5-year cumulative incidence, 29.2%±9.5% compared to 10.9%±4.7% for TYMS 2/3 or 2/2 genotypes, p = 0.02). Increased expression levels of these two target genes (p 〈 0.0001 and p = 0.09, respectively) were consistent with resistance to the drugs interacting with these gene products. For central nervous system relapse, among the HR group, the vitamin D receptor (VDR) start site (p = 0.02) and intron 8 genotypes (p = 0.04) predisposed, whereas for LR patients the TYMS 3/3 genotype predisposed (p = 0.04). The genotypes associated with outcome have pharmacologic plausibility: e.g., high GST activity (GSTM1 non-null) could cause anticancer drug resistance; high TYMS activity (TYMS 3/3) would be less inhibited by antifolates. In conclusion, germline polymorphisms influence the outcome of antileukemic therapy, and therefore represent determinants of response that can be used to optimize therapy.

Description: Key Points IDH2 R140Q expression in TF-1 cells can induce DNA and histone hypermethylation that mirrors human IDH2 mutant acute myeloid leukemia. The hypermethylation can be reversed on treatment with AGI-6780, an IDH2 mutant-specific small-molecule inhibitor.

Description: Gene expression profiling of 207 uniformly treated children with high-risk B-progenitor acute lymphoblastic leukemia revealed 29 of 207 cases (14%) with markedly elevated expression of CRLF2 (cytokine receptor-like factor 2). Each of the 29 cases harbored a genomic rearrangement of CRLF2: 18 of 29 (62%) had a translocation of the immunoglobulin heavy chain gene IGH@ on 14q32 to CRLF2 in the pseudoautosomal region 1 of Xp22.3/Yp11.3, whereas 10 (34%) cases had a 320-kb interstitial deletion centromeric of CRLF2, resulting in a P2RY8-CRLF2 fusion. One case had both IGH@-CRLF2 and P2RY8-CRLF2, and another had a novel CRLF2 rearrangement. Only 2 of 29 cases were Down syndrome. CRLF2 rearrangements were significantly associated with activating mutations of JAK1 or JAK2, deletion or mutation of IKZF1, and Hispanic/Latino ethnicity (Fisher exact test, P 〈 .001 for each). Within this cohort, patients with CRLF2 rearrangements had extremely poor treatment outcomes compared with those without CRLF2 rearrangements (35.3% vs 71.3% relapse-free survival at 4 years; P 〈 .001). Together, these observations suggest that activation of CRLF2 expression, mutation of JAK kinases, and alterations of IKZF1 cooperate to promote B-cell leukemogenesis and identify these pathways as important therapeutic targets in this disease. This trial was registered at www.clinicaltrials.gov as #NCT00005603.