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Myelodysplastic syndrome (MDS) is a heterogeneous group of clonal myeloid malignancies. Though several recurrent mutations are closely correlated with clinical outcomes, data concerning the association between mutation variant allele frequencies (VAF) and prognosis are limited. In this study, we performed comprehensive VAF analyses of relevant myeloid-malignancy related mutations in 698 MDS patients and correlated the results with their prognosis. Mutation VAF in DNMT3A, TET2, ASXL1, EZH2, SETBP1, BCOR, SFSF2, ZRSR2, and TP53 mutations correlated with outcomes. In multivariable analysis, DNMT3A and ZRSR2 mutations with high VAF and mutant IDH2, CBL, U2AF1, and TP53 were independent poor prognostic factors for overall survival. A substantial portion of patients in each revised International Prognostic Scoring System (IPSS-R) risk group could be adjusted to different prognostic groups based on the integrated VAF and mutational profiles. Patients with these unfavorable mutations in each IPSS-R risk subgroup had survivals worse than other patients of the same risk but similar to those in the next higher-risk subgroup. Furthermore, patients harboring U2AF1 mutation might benefit from hypomethylating agents. This study demonstrated the critical role of VAF of mutations for risk stratification in MDS patients and may be incorporated in novel scoring systems.

Somatic gene mutations are key determinants of outcome in patients with myelodysplastic syndromes (MDS) and secondary AML (sAML). In particular, patients with TP53 mutations represent a distinct molecular cohort with uniformly poor prognosis. The precise pathogenetic mechanisms underlying these inferior outcomes have not been delineated. In this study, we characterized the immunological features of the malignant clone and alterations in the immune microenvironment in patients with TP53-mutant and wild-type MDS or sAML. Notably, PDL1 expression is significantly increased in hematopoietic stem cells of patients with TP53 mutations, which is associated with MYC upregulation and marked downregulation of MYC’s negative regulator miR-34a, a p53 transcription target. Notably, patients with TP53 mutations display significantly reduced numbers of bone marrow–infiltrating OX40+ cytotoxic T cells and helper T cells, as well as decreased ICOS+ and 4-1BB+ natural killer cells. Further, highly immunosuppressive regulatory T cells (Tregs) (ie, ICOShigh/PD-1−) and myeloid-derived suppressor cells (PD-1low) are expanded in cases with TP53 mutations. Finally, a higher proportion of bone marrow–infiltrating ICOShigh/PD-1− Treg cells is a highly significant independent predictor of overall survival. We conclude that the microenvironment of TP53 mutant MDS and sAML has an immune-privileged, evasive phenotype that may be a primary driver of poor outcomes and submit that immunomodulatory therapeutic strategies may offer a benefit for this molecularly defined subpopulation.

Background: Essential thrombocythemia (ET) is a subtype of chronic myeloproliferative neoplasms (MPN) characterized by thrombocytosis and disease-related symptoms, which may be difficult to manage. Patients with ET are also at higher risk of thrombosis and hemorrhage. Ideal therapeutic approaches should achieve adequate cytoreduction, reduce the risk of thrombo-hemorrhagic complications, and prevent progression to post-ET myelofibrosis (PET-MF) or secondary acute myeloid leukemia (AML). Low-dose aspirin with hydroxyurea (HU) is typically given as first-line therapy in high-risk patients. However, approximately 20-40% of ET patients become HU-intolerant or -resistant. In ET, resistance and/or intolerance portend an increased risk of thrombosis, hemorrhage, disease transformation and death. There is a paucity of prospective clinical trial data to guide management of ET patients who are HU resistant or intolerant. P1101 is a next generation monopegylated interferon (IFN) alfa-2b, developed specifically to treat MPNs, including ET. Study Design and Methods: The SURPASS-ET trial (NCT04285086) is a Phase 3, open-label, multicenter, randomized, active-controlled study to assess the efficacy, safety, tolerability, and pharmacokinetics (PK) of P1101 after 12 months of treatment compared with anagrelide as second line therapy for subjects with ET who have shown resistance or intolerance to HU. The primary endpoint is durable modified ELN composite response at 9 and 12 months from dosing. Cochran-Mantel-Haenszel test will be used for comparing the primary endpoint in the two treatment arms. The PK parameters of P1101, including (but not limited to) C min, T max, C max, and area-under-curve (AUC) will be derived using PPK analysis and the relationship between exposure and efficacy and safety endpoints will be examined using E-R analysis. Evaluation of efficacy will include clinical laboratory assessments, allelic burden measurements of CALR, JAK2, and MPL, spleen size measurements, bone marrow sampling (optional), EQ-5D-3L, and MPN Symptom Assessment Form Total Symptom Score (MPN-SAF TSS) assessments. A total of 130 randomized subjects is planned to detect a difference of 40% (P1101) versus 15% (anagrelide) in durable ELN response rate with 90% power at alpha level = 0.05 using the chi-square test. To account for possible non-evaluability (e.g., no follow-up data), approximately 160 subjects will be randomized in this study to get 130 completed patients. Because of uncertainty in the assumptions on which the calculation of the sample size is based, an interim analysis for sample size adjustment will be implemented. Major inclusion criteria include subjects diagnosed with high-risk ET (either older than 60 years and JAK2V617F-positive at screening or having disease-related thrombosis or hemorrhage in the past), diagnosed according to the World Health Organization (WHO) 2016 criteria, documented resistance/intolerance to HU and IFN naïve or anti-P1101 binding antibody negative. Key exclusion criteria include pregnant females, significant cardiovascular disease, documented autoimmune disease and a history or presence of clinically significant depression or neurological disease. The study involves approximately 65 sites across the US, Taiwan, Japan, China, Hong Kong, Singapore, S. Korea, Canada, and Europe. To-date 55 patients (54 Asians, 1 Caucasian) have been randomized. The mean and median age at recruitment was 58.9 years (SD: 14.34) and 63 years (range 21 to 80 years) respectively. Twenty-seven men (49.1%) and twenty-eight women (50.9%) were recruited. Forty-two subjects (76.4%) had a TSS < 20. The study is being overseen by a Data Safety Monitoring Board (DSMB). Figure 1 Figure 1. Disclosures Mesa: Gilead: Research Funding; Promedior: Research Funding; AOP: Consultancy; Incyte Corporation: Consultancy, Research Funding; Abbvie: Research Funding; Genentech: Research Funding; La Jolla Pharma: Consultancy; Novartis: Consultancy; Sierra Oncology: Consultancy, Research Funding; Samus: Research Funding; Pharma: Consultancy; CTI: Research Funding; Celgene: Research Funding; Constellation Pharmaceuticals: Consultancy, Research Funding; CTI: Research Funding. Komatsu: Fujifilm Wako Pure Chemical Corporation: Research Funding; Fuso Pharmaceutical Industries, Ltd.: Research Funding; Japan Tobacco Inc.: Consultancy; Otsuka Pharmaceutical Co. Ltd: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis Pharma KK: Consultancy, Research Funding, Speakers Bureau; Shire Japan KK: Consultancy, Research Funding, Speakers Bureau; PharmaEssentia Japan KK: Consultancy, Current Employment, Research Funding; Chugai Pharmaceutical Co., Ltd.: Research Funding; Kyowa Hakko Kirin Co., Ltd.: Research Funding. Sato: PharmaEssentia Japan KK: Current Employment. Qin: PharmaEssentia Corp.: Current Employment. Urbanski: PharmaEssentia Corporation: Current Employment. Shih: PharmaEssentia Corporation: Consultancy. Zagrijtschuk: PharmaEssentia U.S.A. Corp.: Current Employment. Zimmerman: PharmaEssentia Corporation: Current Employment. Verstovsek: Gilead: Research Funding; Protagonist Therapeutics: Research Funding; NS Pharma: Research Funding; Incyte Corporation: Consultancy, Research Funding; PharmaEssentia: Research Funding; Ital Pharma: Research Funding; CTI BioPharma: Research Funding; Blueprint Medicines Corp: Research Funding; AstraZeneca: Research Funding; Promedior: Research Funding; Genentech: Research Funding; Celgene: Consultancy, Research Funding; Roche: Research Funding; Novartis: Consultancy, Research Funding; Sierra Oncology: Consultancy, Research Funding; Constellation: Consultancy; Pragmatist: Consultancy.

Background: More than 50% of AML patients had hyperactivation of PI3K-AKT-mTOR signaling. Those patients are supposed to be associated with poor prognosis and chemotherapy resistance. The PI3K-AKT-mTOR signaling involves many cellular processes, including mRNA translation, cellular metabolism, and protein turnover. Omipalisib is a dual PI3K/mTOR inhibitor that exhibits anti-tumor activity in several cancers. However, the precise metabolic consequences in response to PI3K/mTOR dual inhibitor are still not fully studied in AML. Aims: To evaluate the efficacy and to elucidate the metabolic alteration of the anti-cancer effects of omipalisib on leukemic cells from both in vitro and in vivo aspects. Materials and Methods: HL60, THP1, and OCI-AML3 myeloid leukemia cell lines were used in this study. Omipalisib (GSK2126458) was used for in vitro and in vivo experiments. Cell proliferation was measured by Cell Titer 96 AQueous One Solution Cell Proliferation Assay. The protein expression and phosphorylation status were analyzed by immunoblotting. Flow cytometry was used for cell cycle and mitochondrial analysis. The metabolomics profiles were analyzed by Agilent 1290 UHPLC system coupled with 6540-QTOF. RNA-seq was performed using an Illumina NovaSeq 6000 platform. Differentially expressed genes (DEGs) between control and omipalisib groups were identified by EBseq. A threshold of fold change ≥2 (or ≤0.5) and p ≤ 0.05 was used to select the DEGs. The mRNA quantification was measured by QuantStudio 3 Real-Time PCR Systems. The oxygen consumption rate (OCR) was analyzed by the XFe 24 extracellular flux analyzer. The CAnN.Cg-Foxn1 nu/CrlNarl mice were used for evaluating in vivo efficacy of omipalisib in murine model. Results: We demonstrated the anti-proliferation effect of omipalisib on AML cell lines with different genetic background. The IC 50 of OCI-AML3, THP1, and HL60 were 16.97nM, 9.35 nM, and 18.69 nM, respectively. Omipalisib could significantly induce G 0/G 1 cell cycle arrest in all three cell lines. As expected, omipalisib could significantly down-regulate the phosphorylation of AKT, mTOR, S6K and 4E-BP1. Metabolomics profiling analysis revealed that 24 of the 137 tested metabolites were significantly different between the control group and the omipalisib-treated groups in OCI-AML3 cells. Further metabolic pathway enrichment analysis demonstrated that metabolites related to amino acid metabolisms were significantly reduced following omipalisib treatment. In addition, we identified 300 DEGs between control and omipalisib-treated OCI-AML3 cells; of these, 251 were upregulated and 49 were downregulated. Further gene set enrichment analysis (GSEA) of hallmark gene sets indicated omipalisib treatment was significantly negatively associated with E2F targets, Myc targets, G2M checkpoint, mTORC1 signaling pathway, and oxidative phosphorylation. Joint-Pathway analysis (MetaboAnalyst 5.0) revealed that 'glycine, serine and threonine metabolism' was the most downregulated pathway in the omipalisib-treated group with p-value of 1.0076E-5 and impact value of 0.86567. qRT-PCR confirmed that several important genes, PHGDH, PSAT1, PSPH, SHMT1/2 and MTHFD1/2 in the serine and glycine synthesis pathway were significantly decrease in the OCI-AML3 cells following treated with omipalisib. OCR analysis indicated that the capacity of the mitochondria to produce energy was reduced after omipalisib treatment. Mitochondrial analysis showed that mitochondria mass and membrane potential decreased after omipalisib treatment, indicating the biosynthesis and functions of mitochondrial may be affected by omipalisib. In vivo studies showed that oral administration of 0.2 or 1 mg/kg omipalisib in mice could significantly retard tumor growth without obvious changes in body weight. Summary: We found that nanomolar levels of omipalisib could significantly inhibit cell growth and induce G 0/G 1 cell cycle arrest in myeloid leukemia cells. Joint-Pathway analysis of RNA-seq and metabolomics data revealed that omipalisib mainly altered serine and glycine metabolism. Further experiments indicated that serine synthesis pathway could be suppressed by omipalisib at least in part through disrupting PI3K-AKT-mTOR signaling. In vivo xenograft model, omipalisib could retard tumor growth at as low as 0.2 mg/kg. This information may be potentially suitable for future clinical application. Figure 1 Figure 1. Disclosures Chou: Kirin: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria, Research Funding; Novartis: Honoraria, Other: Advisory Board; Pfizer: Honoraria, Other: Advisory Board; IQVIA: Honoraria, Other: Advisory Board; Abbvie: Honoraria, Other: Advisory Board, Research Funding; Celgene: Honoraria, Other: Advisory Board, Research Funding. Tien: AbbVie: Honoraria; Celgene: Honoraria, Research Funding; Novartis: Honoraria.

Introduction: AL (light-chain) amyloidosis is a rare disease with an incidence rate of approximately 12-13 per million population in Western countries. To date, the epidemiology of AL amyloidosis in Asian countries has not been described. Population-based clinical information about AL amyloidosis is needed to understand disease characteristics and the impacts of future treatments on the disease Methods: We conducted a retrospective cohort study using the Taiwan National Healthcare Insurance Research database (NHIRD) and Death Registry to estimate the incidence, prevalence, all-cause mortality rate and characteristics of patients with AL amyloidosis in Taiwan. All patients with confirmed newly diagnosed AL amyloidosis (ICD-10 E85.4: Organ-limited amyloidosis, E85.8: Other amyloidosis and E85.9: Amyloidosis, unspecified) from 01 January 2016 until 31 December 2019 were enrolled. Eligible patients had a biopsy record within 12 months prior to, or up to 6 months after the date of diagnosis of AL amyloidosis; and at least two consecutive outpatient claims and/or one inpatient claim amyloidosis in the NHIRD. Patients were followed up until dis-enrolment, death or study end (31 December 2019), whichever occurred first. Results: A total of 841 patients with newly diagnosed AL amyloidosis were identified in Taiwan during the period 01 January 2016 until 31 December 2019. The median age at diagnosis was 61.4 years and 58.7% were men. At diagnosis, cardiac disease was present in 28.54%, renal-related disease in 23.19% and had 7.85% had multiple myeloma (Table). The crude annual incidence of AL amyloidosis was 8.46 per million population in 2016 and 8.31 per million population in 2019 (Figure). The age-adjusted incidence rates were 5.73 and 5.26 per million population, respectively. The crude and age-adjusted prevalence rates of AL amyloidosis remained similar over the study period: the crude prevalence rates were 121 to 142 per million population, and age-adjusted prevalence rate were 81.52 to 99.84 per million population. The all-cause mortality rate ranged from 1.7 to 2.9 per 1000 patients over the study period but was highest (~10 per 1000) in patients aged ≥80 years. There were 501 patients (59.6%) with a biopsy report prior to the AL diagnosis index date. Presenting clinical symptoms were not available in the claims database so we assessed the time period from biopsy to diagnosis. The median time from biopsy until diagnosis was 3.8 months and was longer than 12 months in some patients, with little change observed from year to year. Conclusion: To our knowledge, this is the first known population-based cohort study of non-hereditary amyloidosis in Asia. The incidence of AL amyloidosis in Taiwan appears to be similar to Western countries with higher prevalence in Asia. There was no apparent change in the incidence or prevalence rates over the 4 years of the study. Diagnostic delay is recognized as an important limitation in the treatment of AL amyloidosis. Figure 1 Figure 1. Disclosures Goh: Janssen: Current Employment. Siggins: Janssen Pharmaceuticals: Current Employment. Qiu: Janssen Research & Development LLC: Current Employment, Current holder of individual stocks in a privately-held company. Chou: Abbvie: Honoraria, Other: Advisory Board, Research Funding; Celgene: Honoraria, Other: Advisory Board, Research Funding; IQVIA: Honoraria, Other: Advisory Board; Pfizer: Honoraria, Other: Advisory Board; Novartis: Honoraria, Other: Advisory Board; Bristol Myers Squibb: Honoraria, Research Funding; Kirin: Honoraria, Research Funding. Liu: Janssen Research & Development LLC: Current Employment, Current holder of individual stocks in a privately-held company.

RUNX1 is a member of the core-binding factor family of transcription factors and is imperative for establishing definitive haematopoiesis. Mutated RUNX1 is an adverse risk factor for myelodysplastic syndrome (MDS) and acute myeloid leukaemia (AML). Meanwhile, high expression of RUNX1 is correlated with dismal prognosis in cytogenetically normal AML patients and critical for maintaining leukemic stem cells across AML genetic subgroups. However, the clinical relevancy of RUNX1 expression in MDS patients remains elusive. This study aimed to investigate the prognostic and biologic impacts of RUNX1 expression in MDS patients. We recruited 341 primary MDS patients who had enough bone marrow (BM) samples for RNA and next-generation sequencing. We first examined the difference in RUNX1 expression among patients with wild RUNX1 and N-terminal or C-terminal RUNX1 mutation. Among the 341 patients, 54 (15.8%) harboured RUNX1 mutation, 15 (27.8%) in N-terminal and 39 (72.2%), C-terminal. Patients with C-terminal RUNX1 mutant had higher RUNX1 expression than those with N-terminal RUNX1 mutant or wild RUNX1 (p Regarding survival, we first examined the impact of RUNX1 mutation on survival in this cohort. As expected, patients with mutated RUNX1 had significantly inferior leukaemia-free survival (LFS) and overall survival (OS) than those with unmutated RUNX1 (p=0.007, and p=0.008, respectively). We then explored the effects of RUNX1 expression on patients' survival. Patients with higher RUNX1 expression had significantly inferior LFS and OS than those with lower expression (both p Figure 1 Figure 1. Disclosures Tien: AbbVie: Honoraria; Celgene: Honoraria, Research Funding; Novartis: Honoraria. Chou: Abbvie: Honoraria, Other: Advisory Board, Research Funding; Celgene: Honoraria, Other: Advisory Board, Research Funding; IQVIA: Honoraria, Other: Advisory Board; Pfizer: Honoraria, Other: Advisory Board; Novartis: Honoraria, Other: Advisory Board; Bristol Myers Squibb: Honoraria, Research Funding; Kirin: Honoraria, Research Funding.

Introduction Identification of gene mutation status prior treatment has improved our capability in risk stratifying acute myeloid leukemia (AML) patients greatly, but it is really a labor-exhausting work to identify these mutations. In this this study, we hypothesize immunophenotyping could predict gene mutation and we aim to develop machine learning algorithms that could predict the AML gene mutation status with the immunophenotype by clinical flow cytometry. Method Retrospective clinical data of patients with AML, including demographic (age & gender), molecular genetics, cytogenetics as well as flow cytometry (FC) data at National Taiwan University Hospital were collected. A total of 529 newly diagnosed de novo AML from 2009 to 2019 enrolled this study. The median age at diagnosis was 58 years (Table 1). In total, 428 NPM1, 415 FLT3, 331 CEBPA and 338 RUNX1 gene testing results and a total of 529 initial diagnostic FC data from these patients were used in developing the gene mutation prediction models. Each FC data sample contained 100,000 cells acquired on FACSCantoII machine 6 fluorescent channels with multiple fluorescent markers. The markers measured are listed in Table 2. There were 19 combinations of markers and fluorescent channels which were served as feature inputs of the machine learning framework. Our proposed machine learning framework can be divided as a phenotype representation learning paradigm and a classification model. To derive the phenotype representation, we trained a multivariate Gaussian Mixture Model (GMM) on the 19-dimension FC data to capture the training data distribution and characteristics in a probabilistic unsupervised manner. Then, a Fisher-scoring method was used to vectorize each sample as a high dimensional representation via differential computation in terms of the learned GMM parameters. This Fisher vectorization method transformed samples to a high dimensional feature space as phenotype vectors. We performed analysis of variance (ANOVA)-based feature selection on these representations which were finally fed into the support vector machine (SVM) classifier. To alleviate the negative effects of imbalance classes in gene mutation identification tasks, we applied synthetic minority oversampling technique (SMOTE) algorithm which augmented the minority class by interpolating samples near support vectors. We train independent SVM models to detect the occurrences of the four gene mutation. The algorithm is evaluated by randomly divided 5-fold cross validation which separates 80% data for training and 20% for testing. Results This gene mutation rate of this cohort for NPM1, FLT3, CEBPA and RUNX1 were 22.2% (95/428), 25.1% (104/415), 20.2% (67/331), and 13.6% (46/338), respectively. The average accuracies (ACC) of the prediction model performance for NPM1, FLT3, CEBPA and RUNX1 were 82.6%, 76.3%, 84.2% and 84.1%, respectively, whereas the area under the ROC curve (AUC) were 77.9%, 63.4%, 80.7% and 67.7%, respectively (Table. 3). Conclusions We demonstrated the potential of the correlation of recurrent AML gene mutation status with immunophenotype of AML through our preliminary gene mutation prediction model. Further study with larger cohorts followed by external validation are needed to further evaluate the feasibility of using machine learning based algorithm as one of triage tools to support physicians in aggressive AML clinical decision before receiving molecular genetic reports. Disclosures Ko: Roche: Honoraria.

MYC gene amplification and somatic mutations are frequent in both adult and pediatric AML although how MYC drives and contributes to the development and maintenance of AML has not been resolved. Transcription factor EB (TFEB) is a master regulator of genes that control autophagy and lysosome biogenesis, a central catabolic recycling pathway that regulates cell survival. Given the oncogenic effects of MYC in AML and that the induction of autophagy compromises AML cell growth and survival, we tested if the oncogenic effect of MYC depends on its suppression of TFEB transcription programs in AML. In support of this hypothesis, inducible MYC expression in K562 and THP-1 leukemia cells was sufficient to suppress expression of TFEB and its target genes. Further and conversely, MYC knockdown in NB4 AML cells provoked increased expression of TFEB mRNA and protein, as well as increased expression of TFEB target genes. Notably, dose response studies demonstrated that expression of TFEBS211A, constitutively nuclear form of TFEB that is refractory to control by mTORC1 signaling, dramatically impairs proliferation of HL60, OCI-AML2 and OCI-AML3 AML cells. In addition, induction of TFEBS211A provoked rampant apoptosis. Of important, overexpression of TFEBS211A in HL-60 and OCI-AML3 cells was also sufficient to promote monocytic and granulocytic differentiation, as judged by morphological changes and the acquisition of mature monocytic and granulocytic markers including CD11b, Gr1, and CD15. To identify TFEB targets that might contribute to myeloid/granulocytic differentiation, we performed RNA-seq analysis of HL60 leukemia cells engineered to inducibly express the TFEBS211A transgene. Using a cut-off of fold change>4 with q Surprisingly, among genes induced by TFEB in HL60 cells is IDH1, which catalyzes the production of α-ketoglutarate (α-KG), a required substrate of the TET family of dioxygenases that convert 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC). In particular, TFEBS211A expression provoked increases in levels of α-KG and significant increases in global levels of 5hmC in genomic DNA of HL60 leukemia cells both ex vivo and in vivo. Furthermore, TFEB-mediated induction of IDH1/2 mRNA and protein, and of IDH1 promoter activity, was antagonized by inducible expression of MYC. To assess the global effects of TFEB on 5mC/5hmC landscapes, we performed paired reduced representation bisulfite (BS)- and oxidation bisulfite (oxBS)-sequencing. As predicted, TFEBS211A induced both loss and gains of 5mC, but there were more losses (n = 722) than gains (n = 459) across all 22 chromosomes. Quite remarkably, and consistent with TFEB-provoked increases of 5hmC signals, TFEBS211A exclusively induced 5hmC gains (in a total of 863 genes), and 37% and 36% of these 5hmC gains occurred in promoter regions and CpG islands, and across all 22 chromosomes. Comparison of BS- and oxBS-seq versus RNA-seq analyses of HL60 cells expressing TFEB revealed significant changes in mRNA levels and concomitant differential changes in 5mC and 5hmC marks in KLF4, KLF6, STAT3, TP73, andFOXO1 that have pivotal roles in controlling myeloid cell differentiation and death. Collectively, these findings demonstrate that MYC suppresses TFEB expression and function in AML cells, and that TFEB functions as a tumor suppressor that provokes AML cell differentiation and death. Strikingly, these responses rely on epigenetic control, where TFEB directly induces the transcription of IDH1 and IDH2 to provoke global hydroxylation of 5-methylcytosine and the expression of genes that drive terminal differentiation and apoptosis. Thus, a MYC-TFEB-IDH1/2-TET2 circuit controls AML cell fate. Disclosures Murphy: Merck: Research Funding; Puma Biotech: Research Funding. Ballabio:CASMA Therapeutics: Other: Co-Founder. Kaufmann:Takeda Pharmaceuticals: Research Funding.

Introduction Diffuse large B-cell lymphoma (DLBCL) is the most common B-cell malignancy worldwide. A sizable fraction of these patients ended up succumbing to this fatal disease, so the standard of care after the second-line chemotherapy and/or autologous stem cell transplants (ASCT) remains to be improved. Polatuzumab vedotin-piiq (PoV), an anti-CD79b antibody-drug conjugate, gained accelerated approval by the U.S. Food and Drug Administration in June, 2019. The phase II randomized controlled study (GO29365) showed PoV in combination with bendamustine and rituximab (BR) conferred an additional 22% complete response rate for relapsed/refractory DLBCL, compared with BR alone (40% vs. 18%) . Interestingly, how PoV fares when combined with other salvage therapy remains as an open question. Method DLBCL patients who developed progressive diseases after at least 2 prior lines of therapy including R-CHOP and not previously treated with BR were enrolled into this study between Nov. 2018 and Apr. 2020 at the National Taiwan University Hospital. PoV was given at 1.8 mg/kg in combination with salvage chemotherapies based on clinicians' choices. The compassionate use of PoV was approved by the ethics committee, and clinical data were retrospectively analyzed. Results Thirty-two patients were enrolled in this study. According to the Hans' criteria of immunohistochemical subtypes, 13 patients were germinal center B cell-like (GCB), 17 were non-GCB, and 2 patients were unclassifiable. The median age was 62.5 years (range 20-82). At diagnosis, 26 (81%) patients had stage III or IV diseases, 22 (68.8%) had extranodal involvement, and 24 (75%) had the IPI scores equaled to 3 or higher. The median of failed prior lines of treatment was 4 (range 2-11), including 7 (21.9%) relapsing from ASCT and 16 (50%) were of primary refractory disease. Regarding combination therapies, 20 (62.5%) received BR, 5 (15.6%) had rituximab, 5 (15.6%) had rituximab/carmustine-containing regimens, and rituximab/gemcitabine-based ones were given to 4 (12.5%) patients. The median of cycles of PoV was 4 (range 1-7). Notably, the combinatory use of PoV and salvage chemotherapy helped transition 5 patients to ASCT and 4 to allogeneic SCT. The median overall survival (OS) was 8.9 months (95% confidence interval 6.2-not estimable) with the median follow-up of 11.4 months (range 0.3-20.7). The overall response rate (ORR) was 45.2%, including 29.1% complete response (CR) and 16.1% partial response (PR). The patients achieving CR or PR after PoV had better overall survival (OS) than those who did not (median OS: not reached (NR) vs. 5.6 months, p=0.0001, Figure A). The ORR for patients failing prior 2, 3, 4, and ≥5 lines of treatment were 50% (3/6), 40% (2/5), 50% (4/8), and 42% (5/12), respectively. The patients failing prior 4 lines of treatment had better OS than those with failed prior 5 or more lines (NR vs. 6.47 months). Non-GCB patients had better ORR (69.2% vs. 30.8%) and OS (NR vs. 6.23 months) than GCB ones did. Intriguingly, the patients received SCT had better OS compared with the others (NR vs. 6.23 months, p=0.011, Figure B). As for grade 3 & 4 hematological adverse effects, 16 (50%) patients developed anemia, 20 (62.5%) had thrombocytopenia, and 18 (56.3%) were neutropenic. Grade 5 toxicities included pneumonia (2 patients, 6.3%), fungemia (1, 3.1%), intracranial hemorrhage (1, 3.1%), and other infections (2, 6.3%). Conclusion As the third-line or above treatment for DLBCL in this study, the efficacy and safety associated with PoV-based therapies not only were encouraging but also helped bridge to transplants. The application of this monoclonal antibody-drug conjugate in future clinical trials for DLBCL is expected. Figure Disclosures Tsai: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Chugai: Honoraria; Harvester: Honoraria; Janssen: Honoraria; Kirin: Honoraria; Takeda: Honoraria; BMS: Honoraria; Astellas: Honoraria; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees. Ko:Roche: Honoraria. Cheng:Roche: Honoraria. Huang:MundiPharma: Honoraria; Chugai: Honoraria; Roche: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria; Janssen: Honoraria; Takeda: Honoraria; Bristol Meyer & Squibb: Honoraria.

Introduction Current risk stratification of Acute Lymphoblastic Leukemia (ALL) approach has significantly improve the outcome for pediatric and adolescent ALL. However, the outcome for adult ALL remains poor. With the emerging technologies that could drastically increase the parameters and scales of clinical data for treatment strategy formulation and more new therapeutic agents approved for ALL treatment, a better integrated and more systematic risk stratification method is needed for ALL. In our study, we propose to use artificial intelligence to develop an integral outcome prediction models that include all clinical exam and treatment history, aiming to further improve current risk stratification strategies. Method Retrospective clinical data of patients with ALL, including demographic (age & gender), laboratory results including complete blood count (CBC), white blood count (WBC), molecular genetics, cytogenetics, flow cytometry (FC) and treatment history at National Taiwan University Hospital were collected. A total of 513 newly diagnosed ALL from 2005 to 2017 were enrolled this study. The median age at diagnosis was 20 years and the median follow up duration was 49.1 months, 78.9% of them achieved complete remission (CR), 27.5% had relapsed, 31.6% had received HSCT (Table 1). In total, 243,464 CBC & WBC records, 32 types of anti-neoplastic medications in L01, L03 and L04 ATC code category with a total of 20,043 medication records from these 513 patients were utilized in developing the ALL outcome prediction model. A vectorized representation that captures the static-dynamic clinical aspects of an ALL patient can be learned directly from the collected data. The representation includes both static personal attributes (demographic, and genetic) and time-varying progression of patient's clinical assessment across time (laboratory results, HSCT, and medication). The time-dependent representation was derived from training a deep network architecture of bi-directional long short-term memory network (BLSTM). By taking 7 days as a time step, the BLSTM took the input of Fisher-vector encoded time series of a patient's CBC and WBC, medication, and HSCT records separately. The last output layer, which summarized the relapse/mortality risk exhibited in the measurements of patient's clinical conditions over time, of each separately-learned BLSTM was used as the encoded dynamic clinical representation. The concatenation of the ALL patient's static features and the time-dependent representations were fed into a deep neural network followed by a support vector machine to carry out the final prediction. The prediction models were conducted in 5-fold cross-validation experiments and further evaluated using metrics of accuracy (ACC). Results The median leukemia free survival and median overall survival of these 513 ALL patients are 29.3 months and 61.9 months respectively. The outcome prediction models developed achieved accuracy of next 3-month relapse, relapse or mortality, and mortality prediction reached 86.2%, 74.9% and 64.3% respectively (Table 2). Conclusions Our team has demonstrated the BLSTM-DNN model's potential that is capable in taking multiple and longitudinal clinical measurements into integrated relapse or mortality prediction in AML in 2018 (ASH 2018 #2811) and we have observed the same potential in ALL relapse and mortality prediction. More external and multi-national center studies are needed to further improve the performance of such integrated outcome prediction models. Disclosures Ko: Roche: Honoraria.

Background Ruxolitinib, an oral JAK 1/JAK 2 inhibitor, has been approved for the treatment of intermediate-2 or high-risk myelofibrosis, including primary myelofibrosis (PMF), post-polycythemia vera myelofibrosis (PPV-MF), and post-essential thrombocythemia myelofibrosis (PET-MF) in Taiwan since 2014. This registry aimed to examine the real-world safety profile and treatment pattern of ruxolitinib in Taiwan. Methods This is an observational, multi-center, post-marketing registry study. A total of 98 patients with intermediate-2 or high-risk PMF, PPV-MF, or PET-MF and receiving ruxolitinib (73.5%) or newly initiating ruxolitinib (26.5%) per clinical judgment were enrolled and analyzed in a 2-year follow-up. The primary objective was to collect the safety profile of ruxolitinib under routine practice in Taiwan. Results This interim analysis included results of 98 patients who had received ruxolitinib treatment. The median age was 68.1 years (range, 38 -87 years), 50.0% of patients were male. Of the 98 patients, 51.0% were diagnosed with PMF, 27.1% were PET-MF, and 21.9% were PPV-MF; 70.4% were categorized as Dynamic International Prognostic Scoring System (DIPSS) intermediate-2-risk group and 28.6% were high-risk group when ruxolitinib was initiated. JAK2 mutation was identified in 77.8% of 63 patients examined, while CALR mutation was identified in 6 of the 14 (42.9%) JAK2-unmutated cases. At the time of data cut-off, 23 patients (23.2%) discontinued the study mainly due to death (9.1%), adverse events (2.0%), withdrawal of consent (2.0%), and interruption of ruxolitinib ≥ 3 months (2.0%). The median exposure to ruxolitinib was 14.2 months (range, 0.8 - 37.9 months) from the time of study enrollment. At baseline, 75.4% of patients receiving a starting dose of > 5 - 10 mg bid, 11.2 % receiving > 10 - 15 mg bid, 10.2% receiving 20 mg bid. The prescription appeared to be more conservative than the suggested dose. The dose of 5 - 10 mg bid was prescribed for most patients at study enrollment regardless of different platelet counts (56.5% with platelet counts > 200 × 109/L, 54.5% with platelet counts 100 - 200 × 109/L, 50.0% with platelet counts < 100 × 109/L). The median dose after 6 months was maintained at 10 mg bid. At the time of data cut-off, adverse events (AE) were reported in 77.6% of patients and serious AEs (SAE) observed in 35.7% of patients. The most common non-hematologic AEs (≥ 5% of patients) were infections (pneumonia [9.2%], upper respiratory tract infection [8.2%], urinary tract infection [7.1%]), pyrexia (9.2%), diarrhea (8.2%), hyperkalemia (6.1%), and cough (5.1%). The infections were mainly grade 1/2, without tuberculosis or hepatitis B reactivation reported. Consistent with findings from other ruxolitinib studies, the most common hematologic AEs were anemia (10.2%) and thrombocytopenia (10.2%). However, we observed a lower incidence of anemia and thrombocytopenia compared to other studies (42.2 - 56.3%) and no one discontinued the treatment, indicating that these AEs were tolerable and manageable. Ten patients died but none of them was related to ruxolitinib. Over 48 weeks, ruxolitinib provided a sustained clinical benefit (n = 59), with a significant reduction in MPN-10 total score from 21.4 to 12.0 (P < 0.001). The improvement of symptoms was particularly prominent in naïve patients (change in total score: -12.8, P < 0.001) compared to non-naïve patients (change in total score: -6.1, P = 0.023), especially in itching (-2.7 vs. -0.5, respectively), problems with concentration (-1.8 vs. -0.9, respectively), and filling up quickly when eating (-2.2 vs. -1.1, respectively). In addition, the spleen size was reduced from baseline by 10.9 % in 27 evaluable patients at Week 12 and 16.4% in 13 evaluable patients at Week 24. Conclusions The interim analysis demonstrated that ruxolitinib for patients with intermediate-2 or high-risk myelofibrosis, was well-tolerated in the real-world setting in Taiwan. With a lower starting dose, the incidence of hematological AEs and infection rate appeared to be lower than previous reports. The safety profile was consistent with published data, with neither new safety signal, tuberculosis, nor hepatitis B reactivation detected. Ruxolitinib also provided continuous symptom improvement; however, spleen size reduction, an important goal of ruxolitinib therapy of myelofibrosis, was relatively modest, highlighting the need for dose optimization. Disclosures Hou: Celgene: Research Funding; Abbvie, Astellas, BMS, Celgene, Chugai, Daiichi Sankyo, IQVIA, Johnson & Johnson, Kirin, Merck Sharp & Dohme, Novartis, Pfizer, PharmaEssential, Roche, Takeda: Honoraria. Chen:Novartis: Employment. Lee:Novartis: Employment. Ku:Novartis: Employment.

Background: Prognosis of Acute Myeloid Leukaemia (AML) is guided by chromosomal and molecular profiling. Standard regression approaches may not be optimal for identifying complex gene-gene interactions. Aims: We investigated use of machine-learning (ML) by recursive partitioning (RP) and random forest (RF) analysis on two large AML datasets to develop a hierarchical prognostic risk model. Methods: This study included 2074 non-APL AML cases aged ≤70 from National Taiwan University Hospital (NTUH; n=759) and the German-Austrian AML Study Group (AMLSG; n=1315)(Table 1). Statistical analysis performed in R (version 3.5.1) with RP performed using the rpart (version 4.1-13); RF analysis used randomForestSRC (version 2.7.0) with complexity parameter 0.0007 and minimum subgroup 20. Missing data imputed, branch-points without prognostic significance trimmed. Kaplan-Meier analysis utilized for survival with patients with incomplete data excluded from survival analysis. Overall survival (OS) outcomes were classified into Good (5-year OS >55%), Intermediate (5-year OS >40 - 55%), Poor (5-year OS >20 - 40%) and Very Poor (5-year OS ≤20%). Results: Median age 48 (range 15 - 70) years. Cohorts were evenly matched except higher rate of allograft in complete remission (CR) or CR with incomplete blood count recovery (CRi) for AMLSG (31% vs 18%)(Table 1). CR or CRi achieved in 70%. Median OS for the entire cohort 2.3 years. Machine-learning to develop a prognostic decision-tree for OS based on random 2:1 selection of cases (training-set) and validated on remaining cases (validation-set). Each cohort produced similar RP-trees (Figure 1). Through ML, a decision tree was developed that hierarchically categorized cytogenetic and molecular factors into groupings that most accurately predicted survival. AML features used in the tree included complex karyotype (CK), inv(16), CEBPAdmut, inv(3)/t(3;3), FLT3-ITD, spliceosome mutations (U2AF1, SRSF2 or SF3B1), NPM1mut (in the absence of FLT3-ITD), t(8;21), and other AML identified by single genetic lesions including MLL translocations, NRASmut, isolated TP53mut or isolated ASXL1mut (Table 2). 261 patients (12.5%) were not classified by the model due to incomplete cytogenetic or mutational data and were excluded from survival analysis. In the CK group, a negative effect on prognosis (CR and OS) was conferred by inclusion of high-risk monosomies or structural chromosomal alterations (-7, del(7q), chromosome 17 abnormalities, -5 or del(5q)) or TP53mut, whereas CK cases lacking these lesions had a better prognosis (median OS 5.5 vs 25.1 months, p0.5) also associated with very poor prognosis in the absence of both spliceosome lesions and NPM1mut (median OS 11.6 months). A poor prognostic category comprising triple mutant FLT3-ITD, NPM1mut and DNMT3Amut was identified (median OS 13.2 vs 41.7 months, p=0.002). Cases with spliceosome mutation (SRSF2, U2AF1, SF3B1) had a very poor prognosis if accompanied by either ASXL1mut or potential heterozygous loss of ASXL1 on 20q (either by del(20q) or -20)(median OS 11.8 vs 21.6 months, p=0.003). In NPM1mut disease, ML identified good prognosis for patients who with NRASmut, whereas co-mutation with IDH1mut conferred an intermediate prognosis. In patients with t(8;21) AML, KIT mutations identified patients with intermediate prognosis (median OS 36.6 months vs NR, p=0.02). There were 49 patients (2.4%) with RUNX1mut not categorized to other groups and RUNX1mutper se did not emerge as a prognostic discriminator in this analysis. In comparison to ELN2017 classification, ML reclassified 45% of cases - 30% good, 26% intermediate, 26% poor and 18% very poor (compared to 39% good, 31% intermediate and 30% poor). In establishing the accuracy of predicting death at any time for individual cases the error rate was 35% for our ML model compared to 45% for the ELN2017 classification and 51% for ELN based cytogenetic analysis alone. Conclusion: By combining large datasets from two AML groups using machine-learning, an AML decision-tree was able to refine the accuracy of assessing survival prognosis compared to ELN 2017 classification by providing further prognostic granularity. Disclosures Fleming: Celgene: Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria; Ariad: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees. Tsai:Astellas, BMS, Celgene, Chugai, Johnson & Johnson, Kirin, Novartis, Pfizer, Roche, Takeda: Honoraria; Celgene: Research Funding. Döhner:Celgene, Novartis, Sunesis: Honoraria, Research Funding; AbbVie, Agios, Amgen, Astellas, Astex, Celator, Janssen, Jazz, Seattle Genetics: Consultancy, Honoraria; AROG, Bristol Myers Squibb, Pfizer: Research Funding. Döhner:Daiichi: Honoraria; Jazz: Honoraria; Novartis: Honoraria; Celgene: Honoraria; Janssen: Honoraria; CTI Biopharma: Consultancy, Honoraria. Papaemmanuil:Celgene: Research Funding. Tien:Abbvie: Honoraria; Celgene: Research Funding; Roche: Honoraria; Johnson &Johnson: Honoraria; Daiichi Sankyo: Honoraria; Pfizer: Honoraria; Alexion: Honoraria; Roche: Research Funding; Novartis: Honoraria; Celgene: Honoraria; BMS: Honoraria. Reynolds:Alfred Health: Employment, Other: Biostatistician for trials funded by the Australian government and Abbvie, Amgen, Celgene, GSK, Janssen-Cilag, Merck, Novartis, Takeda, but sponsored by Alfred Health.; AUSTRALASIAN LEUKAEMIA & LYMPHOMA GROUP (ALLG): Consultancy; Novartis AG: Equity Ownership; Novartis Australia: Honoraria. Wei:Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Servier: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria; Astra Zeneca: Honoraria, Research Funding; Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Macrogenics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Genentech: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties: AHW is a former employee of the Walter and Eliza Hall Institute and receives a fraction of its royalty stream related to venetoclax, Research Funding, Speakers Bureau. Hou:Abbvie, Astellas, BMS, Celgene, Chugai, Daiichi Sankyo, IQVIA, Johnson & Johnson, Kirin, Merck Sharp & Dohme, Novartis, Pfizer, PharmaEssential, Roche, Takeda: Honoraria; Celgene: Research Funding.

Introduction Presence of minimal residual disease (MRD) detected by multicolor flow cytometry (MCFC) or quantitative polymerase chain reaction has been recognized as an independent important prognosticator for patients with acute myeloid leukemia (AML). Next-generation sequencing (NGS) can simultaneously detect various mutations and be applied to the majority of patients with AML, but the clinical implication of its use in MRD monitoring remains to be clarified. Recently, it was shown that NGS MRD of mutants other than the common mutations occurring in clonal hematopoiesis of indeterminate potential, including the DTA (DNMT3A, TET2, and ASXL1) mutations, carry prognostic impacts on relapse rates and overall survival (OS) in AML patients. However, the proper time point for NGS MRD detection after treatment is still unclear. Our hypothesis is that the NGS MRD detected at different time points might have different clinical implications. In this regard, we aimed to explore the clinical implication of NGS MRD at different time points in AML patients after chemotherapy. Method We enrolled 306 de novo non-M3 and non-M6 AML patients who attained complete remission (CR) after standard induction chemotherapy and received 2-4 courses of post-remission chemotherapy with high-dose cytarabine with or without anthracycline. We analyzed bone marrow samples serially collected at diagnosis, first CR (1st time point for MRD analysis), and after the first consolidation chemotherapy (2nd time point). We used the TruSight myeloid panel (Illumina) to survey the 54 genes related to myeloid malignancies. Because of the sequencing sensitivity issue, we excluded CEBPA mutation and FLT3-ITD in the subsequent analyses. The median follow-up time was 92.0 months. Result At diagnosis, 91% of patients had at least one gene mutation with a median of 2.0 mutations (range 1-6) per patient; 49.4% had molecular gene mutations alone and 41.6% had both cytogenetic changes and molecular mutations. Mutations in NPM1, DNMT3A, NRAS and IDH2 were the most common mutations. According to the 2017 ELN recommendation, 49.3% of patients were in the favorable-risk group; 29.1%, the intermediate-risk group; and 21.6%, the unfavorable-risk group. Among the patients harboring at least one gene mutation at diagnosis, we randomly assigned them into the training (n=167) and validation cohort (n=111); the two cohorts had similar clinical features, and distribution of cytogenetic and molecular abnormalities. Based on the result from the analysis in the training cohort, we set 0.3% as the cut-off for MRD positivity because patients carried gene mutations lower than this limit had a similar outcome as those without detectable mutations. The allele frequencies of the mutants in MRD ranged from 0.3 to 50.5%. Excluding DTA mutations, 47.3% patients in the training cohort had MRD at 1st time point, and 26.9% at 2nd time point. The patients with positive NGS MRD had significantly higher relapse rate (P=0.042 for 1st MRD and P=0.035 for 2nd MRD), shorter disease-free survival (DFS, P=0.037 for 1st MRD and P=0.007 for 2nd MRD) and OS (P=0.015 for 1st MRD and P Conclusion NGS-based MRD monitoring can be applied to more than 90% of AML patients who have detectable mutations at diagnosis. The presence of NGS MRD after treatment can predict outcome of AML patients, especially after the first consolidation chemotherapy (2nd MRD). Positivity of 2nd MRD is an independent unfavorable prognostic factor for DFS and OS. Further prospective trials are warranted to validate these findings and to clarify the role of pre-emptive treatment. Disclosures Tsai: Celgene: Research Funding; Astellas, BMS, Celgene, Chugai, Johnson & Johnson, Kirin, Novartis, Pfizer, Roche, Takeda: Honoraria. Tien:Novartis: Other: Travel Grant. Hou:Celgene: Research Funding; Abbvie, Astellas, BMS, Celgene, Chugai, Daiichi Sankyo, IQVIA, Johnson & Johnson, Kirin, Merck Sharp & Dohme, Novartis, Pfizer, PharmaEssential, Roche, Takeda: Honoraria. Tien:Celgene: Honoraria; Novartis: Honoraria; Alexion: Honoraria; BMS: Honoraria; Roche: Research Funding; Pfizer: Honoraria; Roche: Honoraria; Celgene: Research Funding; Abbvie: Honoraria; Johnson &Johnson: Honoraria; Daiichi Sankyo: Honoraria.

Introduction One of the contributing factors to the relapse of acute myeloid leukemia (AML) is the presence of leukemia stem cells (LSCs). Interleukin 1 receptor accessory protein (IL1RAP) was reported to be one of the LSC markers. Most studies regarding clinical implications of IL1RAP expression in AML focused on small and selected patient groups. Besides, its correlation with other molecular alterations has not been reported yet in literature. In this study, we aimed to elucidate the relationship between bone marrow IL1RAP expression level and clinical and biological features in patients with de novo non-M3 AML. Furthermore, we would like to explore its prognostic impact and potential underlying mechanism. Method We enrolled 275 newly diagnosed de novo non-M3 AML patients. Among them, 187 (68%) patients received standard induction chemotherapy and 2-4 courses of high-dose cytarabine based post-remission therapy. Analyses of 54 gene mutations were performed by next generation sequencing. The global gene expressions were profiled with the Affymetrix GeneChip Human Transcriptome Array 2.0. Result We used the median as the cut-off value to define the higher and lower IL1RAP expression groups. The patients with higher IL1RAP expression had significantly higher white blood cell counts at diagnosis, higher peripheral blast counts, and higher lactate dehydrogenase levels. Higher IL1RAP expression was closely associated with t(8;21), favorable-risk cytogenetics based on the refined MRC classification, but inversely with unfavorable-risk cytogenetics. Compared with low-expression patients, the high-expression patients had significantly more FLT3/ITD and KIT mutations, but less mutations in U2AF1, TP53, or CEBPA. Among the 187 patients receiving standard intensive chemotherapy, those with lower IL1RAP expression had significantly longer overall survival (OS) than those with higher expression (P=0.047) after a median follow-up time of 91.1 months, but disease-free survival (DFS) was not significantly different between the two groups (P=0.311). Among the 77 patients who relapsed after first complete remission (CR), the second CR rate was similar between the two groups (P=0.649), but the second DFS was significantly longer in the low-expression patients than the high-expression patients (P=0.028) which was also reflected in a significantly longer survival after first relapse in the former group than the latter group (P=0.014). The prognostic impact of IL1RAP expression on OS could be externally validated in the TCGA cohort (P=0.038). Its prognostic implication remained significant in the subgroup of our cohort with intermediate-risk cytogenetics (P=0.006) and those with normal karyotype (P=0.025). In multivariate analysis incorporating age, transplantation status, 2017 ELN risk-stratification and IL1RAP expression as covariates, the higher IL1RAP expression was an independent poor prognostic factor for OS (HR=1.555, P=0.025). The Gene Set Enrichment Analysis revealed significant up-regulation of LSC related genes in the higher IL1RAP expressed patients (Figure 1 and 2). We further profiled genome-wide RNA expression with 70,523 probes to survey the potential molecular mechanisms underlying the IL1RAP expression signature. Totally, 313 differentially expressed genes were identified (>1.5-fold change and Student t-test P Conclusion Higher IL1RAP expression is associated with distinct clinical and genetic alterations. It is an independent prognostic factor for OS irrespective of the risk category based on the ELN classification. Transcription factors, such as GATA1 and GATA2, ABCB6, ELAVL1 and NFκB might be involved in the underlying mechanism. Further prospective large cohort is warrant to validate our findings. Disclosures Tien: Novartis: Other: Travel Grant. Hou:Celgene: Research Funding; Abbvie, Astellas, BMS, Celgene, Chugai, Daiichi Sankyo, IQVIA, Johnson & Johnson, Kirin, Merck Sharp & Dohme, Novartis, Pfizer, PharmaEssential, Roche, Takeda: Honoraria. Tien:Daiichi Sankyo: Honoraria; Roche: Honoraria; Abbvie: Honoraria; Alexion: Honoraria; Celgene: Honoraria; Johnson &Johnson: Honoraria; Novartis: Honoraria; Celgene: Research Funding; BMS: Honoraria; Pfizer: Honoraria; Roche: Research Funding.

Background: Novel agents such as thalidomide and bortezomib have changed the treatment landscape of multiple myeloma (MM). As patients with MM live longer, the risk of developing a second primary malignancy (SPM) increases. Few data describe the rate of SPM in patients with MM in Asia. Objectives: To describe SPM in patients with MM using the Taiwan Cancer Registry according to first-line treatment regimen. Methods: Connections between MM treatment and SPM were made by linking data from the Cancer Registry with the National Health Insurance Research database. All patients with a new diagnosis of MM (ICD-O-3 codes M-97323 and C42) in the cancer registry from 01 January 2000 until 31 June 2014 were included. Patients with a prior malignancy were excluded. Patients must have received at least one treatment for MM in the follow-up period with either novel agents alone, chemotherapy + novel agents, or chemotherapy alone. Patients were followed up for the occurrence of SPMs in the cancer registry from the diagnosis date until death, occurrence of the first SPM, or 31 December 2014, whichever occurred first. The incidence of SPM was calculated from the date of the first administered MM treatment. A competing risk model assessed possible effects of death on incidence rates. Results: There were 4327 eligible patients included in the cohort analysis. The mean age at diagnosis was 66.3 years (SD 11.8) and 57.8% were men. A total of 23.7% of patients received treatment with novel agents alone, 21.9% with chemotherapy + novel agents, and 54.4% with chemotherapy alone. Patients treated with novel agents were younger (mean age 64.4 years vs. 69.6 for chemotherapy + novel agents and 65.9 years for chemotherapy alone; p There were 91 (2.1%) patients who developed at least 1 SPM, of which 83.5% developed solid tumors and 16.5% developed a hematological cancer. The crude incidence of SPM per 1000 person-years from the date of first line treatment was 13.93 in patients who received chemotherapy + novel agents, 9.14 in patients receiving chemotherapy alone and 4.48 in patients who received novel agents alone (Table). In the competing risk model, the sub-distribution hazard ratio (adjusted for comorbidity index, sex, age and year of diagnosis) for developing at least one SPM was 3.34 (95% CI 1.51-7.39; p≤0.03) in patients treated with chemotherapy + novel agents, and 2.93 (95% CI 1.12-7.67 p≤0.03) in patients treated with chemotherapy alone as first line therapy in comparison with patients treated with novel agents alone. The 3-year cumulative probability was 1.88% for developing a solid SPM, and 0.47% for a hematological malignancy. The 3-year cumulative probability of developing any SPM was 0.71% in patients treated with novel agents, 4.88% after chemotherapy + novel agents, and 1.99% after chemotherapy alone (Figure). Conclusion: The availability of novel agents appears to be favorable for the prognosis of MM in terms of SPM development. This study shows that linking high quality databases increases the breadth and depth of knowledge that can be gained from real-world data and could be used in other disease areas. Disclosures Hou: Abbvie, Astellas, BMS, Celgene, Chugai, Daiichi Sankyo, IQVIA, Johnson & Johnson, Kirin, Merck Sharp & Dohme, Novartis, Pfizer, PharmaEssential, Roche, Takeda: Honoraria; Celgene: Research Funding. Liu:Janssen Research & Development: Employment, Equity Ownership. Qiu:Janssen Research & Development: Employment, Equity Ownership. Tien:Celgene: Research Funding; Alexion: Honoraria; Celgene: Honoraria; BMS: Honoraria; Novartis: Honoraria; Johnson &Johnson: Honoraria; Daiichi Sankyo: Honoraria; Roche: Honoraria; Abbvie: Honoraria; Roche: Research Funding; Pfizer: Honoraria. Tang:GSK: Consultancy; Roche: Research Funding; Pfizer: Research Funding; Janssen: Research Funding; Amgen: Research Funding.

Acute myeloid leukemia with t(8;21)(q22;q22) is characterized by considerable clinical and biological heterogeneity leading to relapse in up to 40% of patients. We sequenced coding regions or hotspot areas of 66 recurrently mutated genes in a cohort of 331 t(8;21) patients. At least 1 mutation, in addition to t(8;21), was identified in 95%, with a mean of 2.2 driver mutations per patient. Recurrent mutations occurred in genes related to RAS/RTK signaling (63.4%), epigenetic regulators (45%), cohesin complex (13.6%), MYC signaling (10.3%), and the spliceosome (7.9%). Our study identified mutations in previously unappreciated genes: GIGYF2, DHX15, and G2E3. Based on high mutant levels, pairwise precedence, and stability at relapse, epigenetic regulator mutations were likely to occur before signaling mutations. In 34% of RAS/RTKmutated patients, we identified multiple mutations in the same pathway. Deep sequencing (∼42 000×) of 126 mutations in 62 complete remission samples from 56 patients identified 16 persisting mutations in 12 patients, of whom 5 lacked RUNX1-RUNX1T1 in quantitative polymerase chain reaction analysis. KIThigh mutations defined by a mutant level ≥25% were associated with inferior relapse-free survival (hazard ratio, 1.96; 95% confidence interval, 1.22-3.15; P = .005). Together with age and white blood cell counts, JAK2, FLT3-internal tandem duplicationhigh, and KIThigh mutations were identified as significant prognostic factors for overall survival in multivariate analysis. Whole-exome sequencing was performed on 19 paired diagnosis, remission, and relapse trios. Exome-wide analysis showed an average of 16 mutations with signs of substantial clonal evolution. Based on the resemblance of diagnosis and relapse pairs, genetically stable (n = 13) and unstable (n = 6) subgroups could be identified.

Constitutive innate immune activation is a pathogenetic driver of Myelodysplastic Syndromes (MDS) that directs ineffective hematopoiesis by NLRP3 inflammasome (IFM) assembly and pyroptotic cell death. IFM activation involves recruitment of caspase-1 (casp1) through the adapter protein, ASC, to facilitate autocatalytic cleavage of the zymogen to its active form that is responsible for interleukin (IL)-1β maturation, membrane pore formation and pyroptosis. Oxidized mitochondrial DNA (ox-mtDNA) has been proposed to serve as an alarmin that can activate the IFM by interaction directly with NLRP3 or engagement by DNA sensors, Toll-like receptor 9 (TLR9) and Cyclic GMP-AMP synthase (cGAS). Upon cytolysis, ox-mtDNA is released, permitting interaction with pattern recognition receptors on neighboring cells (Grishman, Pediatric Research, 2012, Shimada, 2012, Immunity. Vollmer, 2004, Immunology). Here, we investigate ox-mtDNA as an IFM-activator and pyroptotic biomarker in MDS. Incubation of TLR9 expressing cell lines, SKM1 (high expresser) and U937 (moderate expresser) with 50ng/mL ox-mtDNA (ND1 gene, amplified with oxidized guanosine) induced IFM activation evidenced by increased p-NFkβ, casp1 and IL-1β cleavage, ASC oligomerization and liberation of ASC specks. Direct interaction of ox-mtDNA with NLRP3 was confirmed by NLRP3 immunoprecipitation followed by probing for mtDNA using ND1 and CYTB specific primers and GAPDH primers as negative genomic control; mtDNA oxidation status was confirmed by dot blot. Furthermore, significantly increased expression of interferon stimulated genes (ISG) was seen in MDS bone marrow (BM) specimens (p≤0.01) compared to normal donors indicating TLR9 and/or cGAS activation. Ox-mtDNA engagement of TLR9 and cGAS was confirmed in MDS specimens by IF colocalization with corresponding IFM activation, as well as in MDS somatic gene mutation murine models (Tet2, SRSF2, U2AF) vs. Wt controls. Evaluation of surface TLR9 by flow cytometry showed significantly increased membrane expression in MDS CD34+ BMMC (n=4) vs. healthy donors (n=13) (p Collectively, these data indicate that ox-mtDNA both directly engages NLRP3 and the DNA sensors TLR9/cGAS to induce IFM activation and pyroptosis, creating a feed forward inflammatory cascade that extends to neighboring cells. Ox-mtDNA may serve as a biomarker and companion diagnostic for pyroptosis execution in MDS. Disclosures List: Celgene: Research Funding.

Background: Myelodysplastic Syndromes (MDS) are genetically and hematologically diverse stem cell malignancies pathogenetically linked to constitutive innate immune activation. Other than rare germline mutations and age, the only known predispositions to adult MDS include prior cytotoxic therapy, clonal hematopoiesis, and autoimmune or chronic inflammatory disorders. Few studies investigating the genetic susceptibility to MDS have been performed owing to the limitations of SNP-array sample size. Here, we report the results from the first unbiased genome wide analysis of germline polymorphisms associated with non-del(5q) MDS using a multinational curated data set. Methods: Association analyses were performed on 2 sample sets (set 1: 555 cases, 2,964 controls; set 2: 352 cases, 2,640 controls) and combined by meta-analysis. Standard SNP- and sample-level QC was applied. Haplotype reference consortium (HRC) imputation was done by the Michigan imputation server (Rsq>0.4) providing 23,278,269 markers for analysis. Gene expression sequencing was performed on an independent sample set from the National Taiwan University Hospital (213 MDS cases, 20 healthy donors; HumanHT-12 v4 Expression BeadChip; Chuang et al. Leukemia 2015). Functional analyses were performed as described. Results: Eight MDS associated loci were identified with lead variants, rs6683416, rs34539210, rs341274, rs1634783, rs7099032, rs2947170, rs4404050, and rs1206818, at 1q31.1 (PLA2G4A), 3p14.1 (FAM19A4), 5q21.3 (EFNA5), 6p21.33, 10q23.1 (GRID1), 12q24.32, 15q26.1, and 20q13.12 (EYA2), respctively. Odds ratio (OR) and p-values of each are listed in Table 1. Using gene expression profiling in an independent MDS sample set, we found expression of these five candidate genes was significantly increased in MDS vs controls (p Conclusion: We describe here the first MDS susceptibility loci ever identified the majority of which have a direct relationship to innate immune activation, a driver of MDS pathogenesis. Expression of genes housing these loci is increased in MDS with demonstrable prognostic and biological relevance. Further, functional studies implicate EYA2 as a novel, biologically rational target for MDS treatment. The direct functions of each polymorphism as well as the potential relationship between these predisposition loci to age-related clonal hematopoiesis merits further investigation. Disclosures Cluzeau: Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Speakers Bureau; AbbVie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Menarini: Consultancy; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Speakers Bureau. Sallman:Celgene: Research Funding, Speakers Bureau. Sokol:Spectrum Pharmaceuticals: Consultancy; Seattle Genetics: Consultancy; Mallinckrodt Pharmaceuticals: Consultancy. Maciejewski:Ra Pharmaceuticals, Inc: Consultancy; Alexion Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Apellis Pharmaceuticals: Consultancy; Ra Pharmaceuticals, Inc: Consultancy; Apellis Pharmaceuticals: Consultancy; Alexion Pharmaceuticals, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. List:Celgene: Research Funding.

Introduction Acute myeloid leukemia (AML) is a highly heterogeneous disease with various genetic abnormalities. Cytogenetics, gene mutations, gene expression profiles, and microRNA expressions affect prognosis in AML patients. Some of these exams are cumbersome and not readily available. In contrast, routine complete blood counting and morphological classification is a simple and real time method, and may be used for prediction of response to treatment. Rapid peripheral blood (PB) blasts clearance after induction chemotherapy has been shown to predict prognosis in AML patients, but those studies recruited small cohorts or lacked molecular correlations. In this study, we aimed to not only investigate the prognostic significance of this method in a large cohort but also extend its implications to genetic and biological levels. Method A cohort of 333 de novo non-M3 AML patients who received standard chemotherapy at the National Taiwan University Hospital from 2003 to 2015 were included. The percentages of their PB blasts in the first week after initiation of induction chemotherapy were examined by morphological observation. Mutation analyses of 15 relevant molecular markers, including FLT3 (ITD and TKD), N-RAS, K-RAS, KIT, CEBPA, RUNX1, as well as NPM1, WT1, ASXL1, MLL/PTD, DNMT3A, IDH1, IDH2, and TET2, were performed in bone marrow mononuclear cells from 165 patients at diagnosis, who had available cryopreserved samples. We profiled whole-genome gene expression using Illumina HumanHT-12 v4 Expression BeadChip (Illumina, San Diego, CA) in 83 patients, who had enough mRNA for analyses. The difference in clinical features, cytogenetics, gene mutations, gene expression profiles, and treatment outcomes between patients who had PB blasts clearance within 7 days and those who failed were analyzed. Results Among the 333 patients, 154 (46.2%) patients achieved clearance of PB blasts within 7 days of starting induction chemotherapy. There was no difference in gender, age, and hemograms at diagnosis between the two groups. The patients failed to clear PB blasts within one week had higher incidence of FAB M0 (5.6% vs. 0.6%, p=0.012), higher percentage of 2017 European LeukemiaNet (ELN) adverse-risk category (40.8% vs. 26.0%, p=0.004), and lower incidence of mutated NPM1 (10.6% vs. 22.5%, p=0.039), FLT3-ITD (11.8% vs. 26.6%, p=0.015), and biallelic mutated CEBPA (9.8% vs. 24.1%, p=0.015) than those who cleared the PB blasts in 7 days. Failure to clear PB blasts within 7 days was a significant unfavorable risk factor for overall survival (OS) [5-year survival rate 53.3% vs. 76.0%, p=0.004 (figure 1)], and relapse-free survival (RFS) [median RFS 6.6 months vs. 18.6 month, p We profiled the global mRNA expression to explore the possible underlying molecular pathways which distinguish these two groups of patients. We identified 192 unique genes with differential expression (> 1.5 fold change, t-test p < 0.05). Gene-annotation enrichment analysis using DAVID 6.8 revealed that these differentially expressed genes were associated with abundant biological functions in a variety of categories. Among them were genes that were associated with cell proliferation (p = 9.68 × 10−4), and apoptosis (p = 3.08 × 10−3). Gene Set Enrichment Analysis (GSEA) revealed significant enrichment in "genes up-regulated in hematopoietic stem cells compared to hematopoietic progenitor cells" (empirical p Conclusion This study demonstrated that rapid clearance of PB blasts is an independent favorable prognostic factor irrespective of age, WBC and 2017 ELN risk classification, and would be a simple and real time tool to predict the patients' prognosis. This parameter separates the patients into groups with distinctive clinical and biological features. Further prospective and larger cohorts are needed to confirm our observations. Disclosures No relevant conflicts of interest to declare.

Background: Internal tandem duplication in the juxtamembranal region of FLT3 gene (FLT3-ITD) is one of the most common mutations in acute myeloid leukemia (AML), resulting in constitutive activation of FLT3 signaling pathway. Therefore FLT3 have been proved to be as a useful target for AML treatment. Previously, we demonstrated that cabozantinib, an oral multi-target tyrosine kinase inhibitor (TKI), could selectively cytotoxic to AML cells with FLT3-ITD (MV4-11 and Molm13). Recently, cabozantinib was reported to be well tolerated in AML patients with FLT3-ITD and potentially be useful in the treatment of AML with FLT3-ITD. However, it is known that TKI-resistance in AML often cause higher relapse rates and lower survival rates. In order to study the drug resistance mechanism, we established cabozantinib-resistant cell lines from MV4-11 and Molm13 cells, after gradual escalating concentration of cabozantinib incubation, with increasing IC50 from 9.5nM to 1.5μM and from 1.06nM to 473.36nM, respectively. The cabozantinib-resistance cell lines were named MV4-11 XR and Molm-13 XR, respectively. Aims: To elucidate the mechanism of survival advantage of cabozantinib-resistance of MV4-11-XR and Molm13-XR. Materials and Methods : The differential expression genes (DEGs) were examined using RNA-seq (Illumina NextSeq-500). Metascape recourse and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analyses were performed to predict the biological functions of DEGs. Quantitative PCR (Q-PCR) were used to validate the RNA-seq results. The extracellular acidification rate (ECAR) was measured using Seahorse bio-analyzer. In addition, to investigate the mitochondrial metabolism, analyses of oxygen consumption rate (OCR), glucose uptake, GAPDH activity, lactate production, ATP content were performed. Results: The gene expression profile in MV4-11 cells and Molm13 cells were used as baselines to establish the up- or down-regulated genes in MV4-11-XR and Molm13-XR cells, respectively. The FPKM were estimated with the selection criteria of q value1 or Conclusion: Our study highlights that alteration of metabolic pathways may contribute cabozantinib resistance. We suggest that targeting these pathways may be a viable strategy to overcome cabozantinib resistance. Disclosures No relevant conflicts of interest to declare.

Background The Philadelphia chromosome−negative classical myeloproliferative neoplasms ([MPNs], including essential thrombocythemia [ET], polycythemia vera [PV], and myelofibrosis [MF]), are generally associated with a substantial disease burden, often leading to a reduced quality of life (QOL) and shortened survival in many patients (pts). There has been a lack of estimates for the incidence/prevalence and treatment patterns of MPNs in many regions of the world, including countries from South Asia, Asia Pacific, Middle East, and Turkey. Hence, there is a need to establish databases like registries, which would provide information on the "real-world" data in these regions. The MERGE registry was initiated with an objective to collect data on the epidemiological indices of MPNs and existing treatment patterns in Asia, including Middle East, Turkey, and Algeria. This primary descriptive analysis from the MERGE registry was performed to estimate the incidence/prevalence, natural disease course, and treatment patterns of MPNs in these countries. Methods MERGE is a multinational, multicenter, nonintervention study that included adult pts with MPNs, who were diagnosed according to World Health Organization 2008 criteria. The data were collected retrospectively (since diagnosis) and prospectively after enrollment in the study. Disease assessments were scheduled every 6 months up to 5 visits, with a minimum of 2 years of follow-up. Pts who participated or were participating in a randomized clinical trial were allowed. Data were analyzed descriptively. Results In total, 884 MPN pts (ET=373, PV=301, MF=169, and unclassified=41) were included in the full analysis data set. The median age was 58 years (range, 47-66 years; younger compared to other regions) and 50% pts were males. Baseline pt characteristics by MPN subtype are summarized in Table 1. About 57% of pts were diagnosed by incidental finding of abnormal blood results followed by bone marrow evaluation. In these countries, the prevalence and incidence of MPNs are estimated to be 57-81 and 12-15 per 100.000 hospital-patients per year over the last 4 years, respectively. As assessed by MPN Symptom Assessment Form (MPNSAF), 92% of the pts reported at least 1 symptom. At baseline, fatigue was the most common symptom in all 3 MPN subtypes (71% MPN; 78% MF; 71% ET; and 68% PV). Inactivity (64%), early satiety (61%), abdominal discomfort (57%), bone pain (56%), weight loss (52%), night sweats (46%), and fever (29%) were more common in MF; whereas, itching in PV pts (50%). MF pts had the highest total symptom score at baseline (mean [SD], 23.5 [17.47]) as compared to ET (mean [SD], 14.6 [14.26]) and PV pts (mean [SD], 16.6 [14.84]). Overall, 64% of pts had ECOG performance status of 0 and 26% had ECOG 1. During study period, the most common nonpharmacological intervention was red cell transfusion in MF and ET pts, and phlebotomy in PV pts. Splenectomy (n=2) and stem cell transplantation (n=4) were rarely employed (6 MF pts). Hydroxyurea (HU) was the most common first-line therapy in all 3 MPN subtypes (overall, 54%; PV, 61%; ET, 54%; and MF, 39%), followed by aspirin. Other common first-line therapies were anagrelide (10%) and interferon (9%) in ET pts, antineoplastic (6%) and clopidogrel (6%) in PV, and JAK2 inhibitors in MF pts (15%). More than 75% of the induction therapies were monotherapies, with less than 3% of pts receiving 3 or more drug combinations as primary treatment. Patients with MF often received monotherapy (81%), than the other patients with MPN. Median duration of first-line therapy was about 6 months (95% CI, 1-21 months), and first-line therapy discontinuation rates of 35%, 36%, and 30% were noted in ET, PV and MF pts, respectively. Interferon was used in 8% of in the second-line setting. JAK2 inhibitors were more frequently (14%-17%) used in the second-and third-line settings. Conclusions The prevalence and incidence of MPNs in countries from Asia Pacific were derived using the number of pts visiting the corresponding hospitals. Thus, the resulting incidence and prevalence reported here are not directly comparable with the country-based prevalence/incidence and may overestimate the actual values. At baseline, pts with MPNs had significant disease burden. The most common first-line therapy was HU, though discontinuation rates of first-line therapies were high, and JAK2 inhibitors were mostly used in the second-line/third-line settings. Disclosures Yassin: Novartis: Research Funding. Taher:La Jolla Pharmaceutical: Research Funding; Ionis Pharmaceuticals: Consultancy; Celgene Corp.: Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Protagonist Therapeutics: Consultancy. Kim:Novartis Korea: Honoraria. Rippin:Employee of IQVIA - doing consultancy for Novartis: Consultancy. Sadek:Novartis Pharmaceutical Corporation: Employment. Siddiqui:Novartis Pharma AG: Employment, Equity Ownership. Wong:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.

Background: The pathogenesis of Myelodysplastic Syndromes (MDS) is linked to constitutive innate immune stimulation that converges upon the NLRP3 inflammasome to induce pyroptosis, a caspase-1 dependent cell death. We have shown that inflammasome assembly is initiated by both cell-extrinsic stimuli such as S100A9 elaborated by Myeloid-Derived Suppressor Cells (MDSC), as well as cell-intrinsic somatic gene mutations (SGM) (Basiorka A, et. al. Blood 2016). SGM of varied classes evoke replication stress caused by transcriptional pauses that can expose genomic DNA to cytosolic sensors through unresolved R-loops or micronuclei formation. The cGMP-AMP Synthase-Stimulator of Interferon Genes (cGAS-STING) is a cell-intrinsic DNA surveillance pathway recognizing both cytosolic pathogenic and autologous DNA, leading to interferon stimulated gene (ISG) transcription and NLRP3 inflammasome activation, key biological features of MDS (Pellagatti A, et. al. Blood 2006; 108:337.). Here, we investigate the contribution of genomic cytosolic DNA engagement by cGAS-STING to NLRP3 inflammasome activation in MDS. Methods: MDS patient and healthy donor bone marrow mononuclear cells (BMMC) were isolated by Ficoll®-Hipaque method from consented participants at the Moffitt Cancer Center or the National Taiwan University Hospital (NTUH). Immortalized murine C57BL/6 Tet2-/- and MX1Cre/SRSF2P95H as well as respective wild type (WT) control BMMCs were used as MDS SGM models. Results: We first assessed cGAS-STING activation in MDS BMMC by measuring ISG response by microarray, demonstrating profoundly increased expression of ISG15, CXCL10, Samd9l, and Ifi27l2 in MDS BMMC (n=213) compared to healthy control BMMC (n=20) (p Conclusion: These data indicate that cGAS-STING engages redundant sources of cytosolic genomic-DNA in MDS to initiate a Type I interferon response and NLRP3 inflammasome activation. Inhibition of the cGAS-STING axis may represent a novel therapeutic strategy for investigation in MDS. Disclosures List: Celgene: Research Funding.

Background The Philadelphia chromosome−negative classical MPNs (myelofibrosis [MF], polycythemia vera [PV], and essential thrombocythemia [ET]) are associated with a pronounced symptom burden, including fatigue, night sweats, itching, and inactivity that may affect patients' HRQOL. There is a limited real-world evidence from many of the Asian countries, including Middle East, regarding the impact of MPNs on HRQOL, or the economic burden associated with these diseases. MERGE is a multinational, multicenter, nonintervention study conducted in adult patients with MPNs in Asia, including Middle East, Turkey, and Algeria. The present analysis evaluated the impact of MPNs on HRQOL of patients from MERGE and explored the association of HRQOL with the clinical outcomes and resource utilization. Method The MERGE registry included patients with MPN diagnosed as per the World Health Organization 2008 criteria. Patients were planned to be followed up for 2 years (5 visits over the course of study). MPN Symptom Assessment Form Total Symptom Score (MPNSAF TSS) was administered during the routine biannual follow-up visits to assess the HRQOL. MPNSAF TSS score was calculated only for patients who completed at least 6 of the 10 items on the MPNSAF TSS questionnaire. The level of inter-rater agreement between physicians and patients on the proportion of symptomatic patients was assessed through Cohen's Kappa coefficient. Further, an ANCOVA (Analysis of covariance) model was applied to estimate the influence of the baseline variables (age, sex, weight, height, family history of MPNs, comorbidities, time to initial MPNs diagnosis, type of MPN initial diagnosis, baseline hemoglobin and platelet count, Eastern Cooperative Oncology Group Performance Status [ECOG PS], and time since diagnosis to treatment initiation) on the TSS score. Variables with univariate P-value < 0.20 were included in the multivariate model. Furthermore, medical resource utilization was assessed by evaluating the inpatient and outpatient visits, hospice care, emergency room visits, and day care. Results Of the 884 eligible patients with MPNs, 169 had MF, 301 had PV, 373 had ET, and 41 had unclassified MPN. During the study, 64% of patients received hydroxyurea, 15% interferon, 15% JAK inhibitors, and 10% anagrelide either alone or in combination. At baseline, the proportion of patients presenting at least 1 of the symptoms was higher in the MF group (96.4%), compared to the total MPN patients (91.8%). In addition, the TSS (mean [SD]) at baseline was highest in the patients with MF (23.5 [17.47]) as compared to patients with ET (14.6 [14.26]) and PV (16.6 [14.84]). During the study duration and follow-up, the TSS remained approximately constant at subsequent visits. Physicians reported a lower proportion of symptomatic patients than the proportion self-reported by patients, although, there was better agreement between physicians and patients for pruritus and night sweats (Kappa, 0.61-0.80) (Table 1) than for other symptoms (Kappa, 0.41-0.60). Across MPN subtypes, inter-rater agreement was lowest for patients with MF compared to patients with ET or PV. In a multivariate adjusted mixed effect regression model, female gender, type of MPN (MF), presence of comorbidities, lower baseline hemoglobin were independently and positively associated with the symptom score values. Overall, 24.3% of the patients had at least 1 inpatient visit, with a mean duration of 11.1 days. Outpatient visits were the most commonly observed healthcare resource used (95.5%), without remarkable change during the follow-up period. Patients with ET had a lower mean number of inpatient visits (mean [SD]: 0.9 [0.77] days), and patients with MF had more outpatient visits (mean [SD]: 5.2 [3.17] visit) on an average, compared to the entire MPN group. Conclusion Despite being on treatment, patients with MPN in MERGE had substantial symptom burden, which did not change over the course of the study. A discordance between physician and patient perception of symptom assessment was seen in this study, indicating that in addition to spleen and hematological investigations, a more systematic assessment such as the use of MPNSAF TSS could help to better evaluate patients' symptoms and understand the disease and its treatment burden. Disclosures Taher: Celgene Corp.: Research Funding; Ionis Pharmaceuticals: Consultancy; Protagonist Therapeutics: Consultancy; La Jolla Pharmaceutical: Research Funding; Novartis: Consultancy, Honoraria, Research Funding. Yassin:Novartis: Research Funding. Rippin:Employee of IQVIA - doing consultancy for Novartis: Consultancy. Sadek:Novartis Pharmaceutical Corporation: Employment. Siddiqui:Novartis Pharma AG: Employment, Equity Ownership. Wong:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.

Introduction Recent advances in the discovery of the genomic landscape in AML prompts necessity to re-examine the 2017 European LeukemiaNet (ELN) recommendation. In this study we aimed to validate the usefulness of 2017 ELN risk stratification in a large Taiwan cohort with special focus on the prognostic relevance of FLT3-ITD allelic ratio and its interaction with other mutations. Methods We retrospectively included 1040 de novo non-M3 AML patients. AML was risk-stratified according to the 2017 ELN recommendation. 739 (71.1%) patients who received standard chemotherapy were included for survival analysis. Allogeneic hematopoietic stem cell transplantation (HSCT) was performed in 293 (39.6%) patients. Mutational analyses of fifteen genes, including CEBPA, NPM1, FLT3, RUNX1, ASXL1, TP53, splicing factors (SF), such as SRSF2, U2AF1, and SF3B1, as well as KIT, NRAS, KRAS, DNMT3A, TET2, and WT1 were performed. FLT3-ITD/wild allelic ratios were calculated as the ratio of the area under the curve by fragment analysis. High FLT3-ITD allelic ratio (FLT3-ITDhigh) was defined as ³ 0.5 and low allelic ratio (FLT3-ITDlow) defined as < 0.5. Results According to the 2017 ELN risk classification, favorable, intermediate and adverse categories comprised 34.6%, 29.2% and 36.2% patients, respectively. NPM1 mutations and FLT3-ITD, the most common mutations in this cohort, were detected in 217 (20.9%) and 216 (20.8%) patients, respectively, with a significant association between each other. The median value of the FLT3-ITD/wild ratio was 0.68 without difference between NPM1-mutated and NPM1-wild group. Of note, patients with FLT3-ITDhigh had higher WBC count and LDH level than those with FLT3-ITDlow. Overall, the CR rate and relapse rate were 74.2% and 54.7%, respectively and 5-year overall survival (OS) was 43.2±1.9%. The CR rate (92.3%) was higher in the 2017 ELN favorable risk group than in the intermediate (73.0%) and adverse groups (52.0%, P As to the prognostic impact of FLT3-ITD, we showed that FLT3-ITD patients had significantly lower CR rate, higher relapse rate, reduced DFS and OS than those without. There was a strikingly difference in treatment response between the low and high FLT3-ITD allelic ratio groups: CR rate (80.7% vs. 63.6%, P=0.0319), relapse rate (56.5% vs. 66.2%, P=0.329), DFS (14.2 vs. 4.6 months P=0.011) and OS (24.0 vs. 11.9 months, P=0.048). Interestingly, patients with FLT3-ITDhigh had a better OS if they received allogeneic HSCT than those who did not. Among the 2017 ELN favorable-risk category, we found that patients with mutated NPM1 and FLT3-ITDlow had significantly shorter OS (median, not reached vs. 31.6 months, P=0.003, Figure. 1A) and a trend of shorter DFS (median 14.9 months vs. 93.9 months, P=0.089, Figure. 1B) compared to other ELN favorable subgroups. To find the cause of the difference, we investigated the concurrent mutations in the patients with mutated NPM1 and FLT3-ITDlow. 46.2% of them had concurrent poor-risk mutations, such as ASXL1, RUNX1, TP53, WT1, TET2, DNMT3A, and SF mutations. Similarly, among the 2017 ELN intermediate-risk category, patients with mutated NPM1 and FLT3-ITDhigh had more unfavorable outcomes compared to those with wild-type NPM1 and without FLT3-ITD (DFS, median 3.7 vs. 11.6 months, P=0.028 and OS, median, 11.4 vs. 26.5 months, P=0.067). Presence of concurrent poor-risk mutations were also identified in 72.9% of these patients. Based on these findings, we postulated that concomitant poor-risk genetic alterations at least partially affected the prognosis of FLT3/ITD patients. In the cohort of FLT3-ITD patients, patients harboring poor-risk mutations had shorter DFS and OS than those without (P=0.028 and P=0.031, respectively). Further, co-occurrence of FLT3-ITDhigh and poor-risk mutations that predicted a worst outcome, seemed to define a highly adverse prognostic group. Conclusions We showed that ELN 2017 risk classification could well stratify AML patients in Taiwan. The prognostic relevance of FLT3-ITD may further depend on the presence or absence of co-occurring poor-risk genetic alterations, which seemed to add an adverse effect in patients with FLT3-ITD. These observations warrant confirmation in other prospective and large-scale studies. Disclosures Ko: Roche: Research Funding; GNT Biotech & Medicals Crop.: Research Funding; Abbevie: Research Funding; Mumdipharma Taiwan: Consultancy.

Leukemic stem cells (LSCs) possess biological properties shared with normal hematopoietic stem cells. They are responsible for chemoresistance and relapse in acute myeloid leukemia (AML). Although myelodysplastic syndrome (MDS) has traditionally been regarded as a "hematopoietic stem cell disorder", the clinical and biological impact of LSCs on MDS patients are not well defined. To address this question, we used the Affymetrix HTA 2.0 microarray platform to profile 16 out of the 17 recently reported stemness genes (one of them, the ARHGAP22 gene was not included in our array) in our 160 adult primary MDS patients. The diagnoses were based on the 2016 World Health Organization (WHO) classification. Patients with antecedent chemotherapy or hematologic malignancies were excluded. Forty-one (25.6%) patients had MDS with single lineage dysplasia (MDS-SLD), 20 (12.5%) had MDS with ring sideroblasts (MDS-RS), 31 (19.4%) had MDS with multilineage dysplasia (MDS-MLD), 32 (20%) had MDS with excess blasts-1 (MDS-EB1) and 36 (22.5%), MDS-EB2. The risk distribution of the cohort was very-high risk, 15.3%; high risk, 21.3%; intermediate risk, 24.7%; low risk 34.7%; and very-low risk 4% according to the revised international prognosis scoring system (IPSS-R). We identified 4 genes (LAPTM4B, NGFRAP1, NYNRIN, and EMP1) whose expression levels were significantly correlated with overall survival (OS). An LSC4 score (0.731 x LAPTM4B - 1.259 x NGFRAP1 + 0.304 x NYNRIN + 0.231 x EMP1) was constructed based on the weighted sums derived from Cox regression analysis. Higher LSC4 scores were associated with higher IPSS-R scores, complex cytogenetics, and higher incidences of mutations of RUNX1, ASXL1, TP53, SRSF2 and ZRSR2. High-score patients had significantly higher 3-year AML transformation rate (36.3% vs 11.3%, P Disclosures No relevant conflicts of interest to declare.

Recurrent somatic mutation of SRSF2, one of the RNA splicing machinery genes, has been identified in a substantial proportion of patients with myelodysplastic syndrome (MDS). However, the clinical and biologic characteristics of MDS with this mutation remain to be addressed. In this study, 34 (14.6%) of the 233 MDS patients were found to have SRSF2 mutation. SRSF2 mutation was closely associated with male sex (P = .001) and older age (P < .001). It occurred concurrently with at least 1 additional mutation in 29 patients (85.3%) and was closely associated with RUNX1, IDH2, and ASXL1 mutations (P = .004, P < .001, and P < .001, respectively). Patients with SRSF2 mutation had an inferior overall survival (P = .010), especially in the lower risk patients. Further exploration showed that the prognostic impact of SRSF2 mutation might be attributed to its close association with old age. Sequential analyses in 173 samples from 66 patients showed that all SRSF2-mutated patients retained their original mutations, whereas none of the SRSF2-wild patients acquired a novel mutation during disease evolution. In conclusion, SRSF2 mutation is associated with distinct clinical and biologic features in MDS patients. It is stable during the clinical course and may play little role in disease progression.

DNMT3A mutations are associated with poor prognosis in acute myeloid leukemia (AML), but the stability of this mutation during the clinical course remains unclear. In the present study of 500 patients with de novo AML, DNMT3A mutations were identified in 14% of total patients and in 22.9% of AML patients with normal karyotype. DNMT3A mutations were positively associated with older age, higher WBC and platelet counts, intermediate-risk and normal cytogenetics, FLT3 internal tandem duplication, and NPM1, PTPN11, and IDH2 mutations, but were negatively associated with CEBPA mutations. Multivariate analysis demonstrated that the DNMT3A mutation was an independent poor prognostic factor for overall survival and relapse-free survival in total patients and also in normokaryotype group. A scoring system incorporating the DNMT3A mutation and 8 other prognostic factors, including age, WBC count, cytogenetics, and gene mutations, into survival analysis was very useful in stratifying AML patients into different prognostic groups (P < .001). Sequential study of 138 patients during the clinical course showed that DNMT3A mutations were stable during AML evolution. In conclusion, DNMT3A mutations are associated with distinct clinical and biologic features and poor prognosis in de novo AML patients. Furthermore, the DNMT3A mutation may be a potential biomarker for monitoring of minimal residual disease.

The impact of WT1 mutations in acute myeloid leukemia (AML) is not completely settled. We aimed to determine the clinical implication of WT1 mutation in 470 de novo non-M3 AML patients and its stability during the clinical course. WT1 mutations were identified in 6.8% of total patients and 8.3% of younger patients with normal karyotype (CN-AML). The WT1 mutation was closely associated with younger age (P < .001), French-American-British M6 subtype (P = .006), and t(7;11)(p15;p15) (P = .003). Multivariate analysis demonstrated that the WT1 mutation was an independent poor prognostic factor for overall survival and relapse-free survival among total patients and the CN-AML group. A scoring system incorporating WT1 mutation, NPM1/FLT3-ITD, CEBPA mutations, and age into survival analysis proved to be very useful to stratify CN-AML patients into different prognostic groups (P < .001). Sequential analyses were performed on 133 patients. WT1 mutations disappeared at complete remission in all WT1-mutated patients studied. At relapse, 3 of the 16 WT1-mutated patients who had paired samples lost the mutation and 2 acquired additional mutations, whereas 3 of 110 WT1-wild patients acquired novel mutations. In conclusion, WT1 mutations are correlated with poor prognosis in AML patients. The mutation status may be changed in some patients during AML progression.

Somatic mutation of the AML1/RUNX1(RUNX1) gene is seen in acute myeloid leukemia (AML) M0 subtype and in AML transformed from myelodysplastic syndrome, but the impact of this gene mutation on survival in AML patients remains unclear. In this study, we sought to determine the clinical implications of RUNX1 mutations in 470 adult patients with de novo non-M3 AML. Sixty-three distinct RUNX1 mutations were identified in 62 persons (13.2%); 32 were in N-terminal and 31, C-terminal. The RUNX1 mutation was closely associated with male sex, older age, lower lactic dehydrogenase value, French-American-British M0/M1 subtypes, and expression of HLA-DR and CD34, but inversely correlated with CD33, CD15, CD19, and CD56 expression. Furthermore, the mutation was positively associated with MLL/PTD but negatively associated with CEBPA and NPM1 mutations. AML patients with RUNX1 mutations had a significantly lower complete remission rate and shorter disease-free and overall survival than those without the mutation. Multivariate analysis demonstrated that RUNX1 mutation was an independent poor prognostic factor for overall survival. Sequential analysis in 133 patients revealed that none acquired novel RUNX1 mutations during clinical courses. Our findings provide evidence that RUNX1 mutations are associated with distinct biologic and clinical characteristics and poor prognosis in patients with de novo AML.

Emerging evidence suggests that progression of hematologic malignancies is associated with angiogenesis. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can provide global and functional imaging of tumor angiogenesis. In this study, we performed bone marrow DCE-MRI prospectively at diagnosis and after induction chemotherapy in 78 de novo acute myeloid leukemia (AML) patients and correlated it with treatment outcome. An algorithm to assess bone marrow angiogenesis by measuring the DCE-MRI time-intensity curve pixel by pixel was developed using 3 distinct parameters: peak enhancement ratio (Peak) to indicate tissue blood perfusion; amplitude (Amp) to reflect vascularity; and volume transfer constant (K trans) to indicate vascular permeability. The Peak and Amp decreased significantly at remission status after induction chemotherapy. Patients with higher Peak or Amp at diagnosis had shorter overall survival and disease-free survival than others. Cox multivariate analysis identified higher Peak value (hazard ratio, 9.181; 95% confidence interval, 1.740-48.437; P = .009) as an independent predictor for overall survival in addition to unfavorable karyotype and old age. Our findings provide evidence that increased bone marrow angiogenesis measured by DCE-MRI can predict adverse clinical outcome in AML patients. DCE-MRI may help to select high-risk phenotype AML patients for tailored antiangiogenic therapy and to monitor treatment response.

Introduction Acute myeloid leukemia (AML) with hyperleukocytosis (HL), commonly defined as white blood cell (WBC) counts >100,000/uL, are intuitively thought as a unique group with dismal prognosis. However, comprehensive studies regarding the clinical characteristics, genetic alterations in this group of patients are limited, and the role of hematopoietic stem cell transplantation (HSCT) is controversial. Method A cohort of 755 de novo AML patients diagnosed from 1994 to 2011 who had cryopreserved cells for analysis were enrolled. The mutation status of 18 genes was determined by Sanger sequencing and/or next generation sequencing (NGS). We compared cytogenetics and relevant mutations in these genes between AML patients with and without HL, and exposed their prognostic implications. Results The median age was 54 (range 15-94). 101 (13.4%) patients had HL. HL was associated with younger age (median age 47 vs. 54, P=0.022), higher peripheral blast percentage (77.6% vs. 39%, P Survival analysis was performed on the 525 patients who received standard intensive chemotherapy; among whom 69 patients had HL. The HL patients had lower complete remission (CR) rates compared to those without (63.8% vs. 78.2%, P=0.009). Further, the HL patients had significantly poorer overall survival (OS) and disease-free survival (DFS) than those without (median 24 months vs. not reached (NR), P=0.042; 6.5 vs. 11.8 months, P=0.005, respectively, Figure 1). Older age, poor-risk cytogenetics, RUNX1, TP53 and WT1 mutations were other poor prognostic factors for OS (median, 18.1 months vs. NR, P Conclusion The HL patients represented 13.4% of our AML cohort and showed distinct clinic features and genetic alterations compared to those without HL. HL was an independent poor prognosis factor irrespective of cytogenetics change or mutation status, and the HL patients may potentially benefit from HSCT. Figure 1 The Kaplan-Meier survival curves for OS (A) and DFS (B) stratified by hyperleukocytosis (HL) or not in the 525 AML patients who received standard intensive chemotherapy (A) (B) Figure 1. The Kaplan-Meier survival curves for OS (A) and DFS (B) stratified by hyperleukocytosis (HL) or not in the 525 AML patients who received standard intensive chemotherapy. / (A). / (B) Figure 2 The Kaplan-Meier survival curves for OS stratified by HSCT or not in the 69 HL patients who received standard intensive chemotherapy Figure 2. The Kaplan-Meier survival curves for OS stratified by HSCT or not in the 69 HL patients who received standard intensive chemotherapy Figure 3 Figure 3. Disclosures No relevant conflicts of interest to declare.

Background Aberrant patterns of alternative splicing (AS) are reported in acute myeloid leukemia and other malignances, but have not yet been investigated in myelodysplastic syndrome (MDS). In addition, mutations in spliceosome genes are especially common in MDS. Therefore, it would be highly interesting to analyze the clinical and biological significance of aberrant AS in MDS. Materials and Methods A total of 243 newly diagnosed MDS patients, including 78 with refractory anemia (RA), 22 with RA with ring sideroblasts(RARS), 76 with RA with excess blasts (RAEB), 24 with RAEB in transformation (RAEBT), and 43 with chronic myelomonocyticleukemia (CMMoL), who had complete clinical and genetic information were enrolled. We also included 20 healthy donors of hematopoietic stem cell transplantation for comparison. We extracted RNA from mononuclear cells (MNC) isolated from the bone marrow (BM), followed by hybridization on the microarrays of AffymetrixHuman Transcriptome Array 2.0, which contained > 6 million distinct probes covering coding, non-coding transcripts, and the exon-exon junctions among 67539 genes (44710 coding genesand 22829 noncoding genes). This comprehensive coverage of exons and junctions facilitated investigation of the splicing patterns of the genes. The aberrant AS was analyzed with the splicing index (SI) method using the default setting of AffymetrixTranscriptome Analysis Console version 3.0 software. The SI of a probe in a gene was derived from the ratio between MDS patients and normal controls in terms of the probe intensity divided by the gene expression level, ie. [intensityof probe A in gene A /gene A expression level]MDS/[intensity of probe A in gene A /gene A expression level]normal control. SI had to be less than -2 or more than 2 to be defined as an aberrant AS event. Results Totally 52730 of 67539 genes (78.1%) on the array were expressed in BM from both MDS patients and normal donor controls. Approximately 17565 of the 52730 expressed genes (33.3%) were differentially spliced between the MDS and normal marrow MNC (P < 0.05). As a whole, 88.9% of these aberrant spliced events were mapped to coding genome and 11.1% to noncoding regions. These aberrant AS exons fell into five common patterns, including exon skipping (57.8%), alternative donor sites (18.1%), alternative acceptor sites (17.8%), intron retention (5.6%) and mutually exclusive exons (0.7%). In average, when compared with the normal marrow MNC, there were 6.4 (4.8-12.0) more aberrant AS events in each AS gene (ASG) in the marrow MNC of 243 MDS patients.More aberrant AS events per ASG implied a more complex aberrant AS pattern.The numbers of aberrant AS events per ASG were not significantly associated with MDS subtypes and frequencies of spliceosome gene mutations. However, with a median follow up of 48.4 months, the patients with more aberrant AS events per ASG had a trend of shorter overall survival (OS) (median 20.1 vs 29.6 months, P=0.074) and a trend of shorter time to acute leukemic transformation (P=0.212) than the others (Fig.1). Further subgroup analysis showed a significantly shorter OS in the patients with more aberrant AS events per ASG than those with less events among RAEB patients (median OS: 10.8 months vs 16.9 months, P=0.007, Fig.2A). In addition, RA patients with more aberrant AS events per ASG had shorter time to acute leukemic transformation than RA patients with fewer aberrant AS events per ASG (P=0.006, Fig.2B). Among the patients without detectable mutations in spliceosome genes or genes related to epigenetic modification, those with more aberrant AS events per ASG also had a shorter OS than the others (median OS: 27.9 months vs not reached, P=0.013, Fig.3). Multivariate analysis in our cohort of 243 MDS patients revealed that higher aberrant AS events per ASG was an unfavorable prognostic factor for OS (P=0.016) independent of age, IPSS-R risk score, and mutations of SF3B1, ASXL1 and TP53. Conclusion To our knowledge, we are the first to present the prognostic impact of aberrant AS pattern in MDS patients. Large prospective cohorts are needed to confirm our observations. Disclosures No relevant conflicts of interest to declare.

Background: Myelodysplastic syndromes (MDS) are highly heterogeneous regarding pathogenesis and clinical outcome. Traditionally, the revised international prognostic scoring system (IPSS-R)incorporating clinical features and cytogenetic abnormalities has been the standard for prognostication, while in recent years, recurrent somatic mutations are becoming increasingly important for this purpose. Additionally, gene expression profiling of coding genes and microRNAs has also emerged as a powerful tool to separate patients into distinct prognostic categories. Long non-coding RNAs (lncRNAs) are transcripts longer than 200 nucleotides without protein-coding capacity. lncRNAs not only participate in normal hematopoiesis, but perturbation of their expressions may contribute to development of acute leukemia. However, the impact of lncRNA expression profiling on the prognosis of MDS patients has not yet been explored to date. Aims: This study was aimed to evaluate lncRNAs expression profiling in MDS and to find out lncRNAs whose expression levels were associated with clinical outcomes. A scoring system was constructed to better risk-stratify MDS patients. We also tried to seek clues to the functionality of these lncRNAs. Materials & Methods: By using the Affymetrix Human Transcriptome Array 2.0 platform, we obtained the global expression profiles of 24120 lncRNAs in 176 adult patients with de novo MDS diagnosed according to the 2008 WHO classification. Through mathematical modeling, we identified six lncRNAs whose expression levels were significantly associated with overall survival (OS). We then constructed a risk scoring system with the weighted sum of each of these six lncRNAs, and evaluated the correlation of the scores with clinical features,cytogenetic abnormalities, gene mutations, andtreatment outcomesof the MDS patients.The reliability of our lncRNA scoring system was assured based on the coefficient of variance obtained from a permutation test, and further validated by using a five-fold cross-validation, in which 80% of the patients were used as the training samples to develop the scoring model, whose prediction performances were evaluated by using the rest of the 20% of the patients. Analysis of mutations in 21 genes was performed by conventional Sanger sequencing technique. Results: Higher lncRNA scores were positively associated with refractory anemia with excess of blasts (RAEB)-1 or RAEB-2 subtypes, complex cytogenetic changes, and IPSS-R high and very high risks, but inversely associated with RCUD, RARS, RCMD subtypes, a normal karyotype, and IPSS-R low risk. Patients with higher lncRNA scores had more frequent RUNX1, ASXL1, TP53, EZH2, SRSF2 and ZRSR2 mutations, shorter OS (median 14.0 months vs. 77.3 months, P Conclusion: Our integrated 6-lncRNA risk scoring system provides distinct insights into the clinical and biological implications of lncRNAs expression in de novo MDS patients. The scoring system represents an independent prognostic factor for survival and leukemic transformation. It may assist improving risk stratification of newly-diagnosed MDS patients. Further prospective trials are necessary to confirm the findings of our study. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures No relevant conflicts of interest to declare.

Alterations of galectin-3 expression are often seen in cancers and may contribute to tumorigenesis, cancer progression, and metastasis. The studies concerning clinical implications of galectin-3 expression in patients with acute myeloid leukemia (AML) are scarce. We investigated the expression of LGALS3, the gene encoding galectin-3, in the bone marrow (BM) mononuclear cells from an original cohort comprising 280 adults with primary non-acute promyelocytic leukemia. Higher LGALS3 expression was closely associated with older age, French-American-British M4/M5 subtypes, CD14 expression on leukemic cells, and PTPN11 mutation, but negatively correlated with CEBPA mutation and FLT3-ITD. Compared with patients with lower LGALS3 expression, those with higher expression had lower complete remission rates, higher primary refractory rates, and shorter overall survival. This result was validated in an independent validation cohort. A scoring system incorporating higher LGALS3 expression and 8 other risk factors, including age, white blood cell count, cytogenetics, and gene mutations, into survival analysis proved to be very useful to stratify patients with AML into different prognostic groups (P < .001). In conclusion, BM LGALS3 expression may serve as a new biomarker to predict clinical outcome in patients with AML, and galectin-3 may serve as a potential therapeutic target in those patients with higher expression of this protein.

Introduction GATA-binding factor 2 (GATA2) contributes to the regulation of hematopoietic stem cell proliferation and differentiation. Mutations of GATA2 are identified in AML patients, but their clinical and biological correlations in AML remain to be delineated. Methods and Materials We determined GATA2 mutations by Sanger sequencing and next generation sequencing in consecutively enrolled 766 newly diagnosed de novo AML patients who had cryopreserved cells for analysis. The expression of GATA2 was also analyzed by microarray in 335 patients. We then looked for the clinical and biological correlations of the expression levels and mutation status of GATA2. Computational network analysis of GATA2 mutations was conducted by Ingenuity Pathway Analysis (IPA) and Gene set enrichment analysis (GSEA). Result GATA2 mutations were detected in 58 patients (7.5%) and were associated with FAB M1 subtype, and intermediate-risk cytogenetics, but negatively associated with M4 subtype and favorable-risk cytogenetics. There was no difference in other clinical parameters such as age, hemogram and LDH levels between the patients with and without GATA2 mutations. GATA2 mutations were closely associated with CEBPA double mutations (44.8% vs. 10.2%, P With a median follow-up time of 25 months (ranges 0 to 160), patients with GATA2 mutations had a trend of better overall survival (OS) than those without GATA2 mutations (median 40.7 vs. 24.9 months P=0.123). Among patients with CEBPA double mutations, there was also a trend toward better OS in patients concomitant with GATA2 mutations (P=0.199). By comparing the mRNA expression profiles between patients with and without GATA2 mutations, we found GATA2 expression levels were higher in those with GATA2 mutations (P=0.003). GATA2 mutations were also associated with a significant change in genes related to cell proliferation and differentiation by IPA. We also performed GSEA analysis to identify modest functional changes related to GATA2 mutation status. Leukemogenesis-related genes were significantly enriched in the GATA2-mutated subgroup (nominal P value= 0.006; Normalized enrichment score= 1.62), whereas gene signatures associated with myeloid differentiation, apoptosis, leukemia cell death, CEBPA and WT1 pathways were enriched in GATA2 -wild type patients. Conclusion GATA2 mutations, which are commonly heterozygous point mutations between amino acids 315 to 361, occur in 7.5% of AML patients and are associated with certain clinical features, a trend of better treatment outcome, and higher GATA2 expression. The GATA2 mutation-associated expression signatures suggest the effects on leukemogenesis by GATA2 mutations. Figure 1. Figure 1. Disclosures Tang: Novartis: Consultancy, Honoraria.

Introduction Risk-stratification of patients with acute myeloid leukemia (AML) can not only improve treatment response, but also reduce side effects of the treatment, especially in the elderly. A number of patient-specific and leukemia-associated factors are related to the poor outcome in older patients with AML. However, comprehensive studies regarding the impact of genetic alterations in this group of patients are limited. Methods and Materials A total of 500 adult patients with newly diagnosed de novo AML who had enough bone marrow cryopreserved cells for analysis at the National Taiwan University Hospital were enrolled consecutively. We compared the clinico-biological features, cytogenetics and molecular gene mutations between patients aged 60 years or older (n=185) and those younger ( Result Among older patients, those received standard intensive chemotherapy had a longer overall survival (OS) than those treated with palliative care. Compared with younger patients, the elderly had a higher incidence of poor-risk cytogenetic changes, but a lower frequency of favorable-risk cytogenetics. The median number of molecular gene mutations at diagnosis was higher in the elderly than the younger. Older patients had significantly higher incidences of PTPN11, NPM1, RUNX1, ASXL1, TET2, DNMT3A, and P53 mutations but a lower frequency of WT1 mutations. In multivariate analysis for OS among the elderly who received standard intensive chemotherapy, high WBC >50,000/μL at diagnosis, RUNX1 mutations, DNMT3A mutations, and P53 mutations were independent worse prognostic factors, while the presence of NPM1 mutations in the abcence of FLT3/ITD mutations was an independent good prognostic factor. The frequency of acquiring one or more adverse genetic alterations was much higher in older patients than younger ones. Further, the pattern of gene mutations could divide older patients with intermediate cytogenetics into three groups with significantly different complete remission rates, OS, and disease-free survival. Conclusion Older AML patients frequently harbored high-risk cytogenetics and gene mutations, and had poorer prognosis. Integration of cytogenetics and molecular alterations could risk-stratify older patients into groups with significant different outcomes. For those patients with poor prognosis under current chemotherapy, novel therapies, such as demethylating agents or other targeted therapies may be indicated. Disclosures Tang: Novartis: Consultancy, Honoraria.

The studies concerning clinical implications of TET2 mutation in patients with primary acute myeloid leukemia (AML) are scarce. We analyzed TET2 mutation in 486 adult patients with primary AML. TET2 mutation occurred in 13.2% of our patients and was closely associated with older age, higher white blood cell and blast counts, lower platelet numbers, normal karyotype, intermediate-risk cytogenetics, isolated trisomy 8, NPM1 mutation, and ASXL1 mutation but mutually exclusive with IDH mutation. TET2 mutation is an unfavorable prognostic factor in patients with intermediate-risk cytogenetics, and its negative impact was further enhanced when the mutation was combined with FLT3-ITD, NPM1-wild, or unfavorable genotypes (other than NPM1+/FLT3-ITD− or CEBPA+). A scoring system integrating TET2 mutation with FLT3-ITD, NPM1, and CEBPA mutations could well separate AML patients with intermediate-risk cytogenetics into 4 groups with different prognoses (P < .0001). Sequential analysis revealed that TET2 mutation detected at diagnosis was frequently lost at relapse; rarely, the mutation was acquired at relapse in those without TET2 mutation at diagnosis. In conclusion, TET2 mutation is associated with poor prognosis in AML patients with intermediate-risk cytogenetics, especially when it is combined with other adverse molecular markers. TET2 mutation appeared to be unstable during disease evolution.

Mutations in the additional sex comb-like 1 (ASXL1) gene were recently shown in various myeloid malignancies, but they have not been comprehensively investigated in acute myeloid leukemia (AML). In this study, we analyzed ASXL1 mutations in exon 12 in 501 adults with de novo AML. ASXL1 mutations were detected in 54 patients (10.8%), 8.9% among those with normal karyotype and 12.9% among those with abnormal cytogenetics. The mutation was closely associated with older age, male sex, isolated trisomy 8, RUNX1 mutation, and expression of human leukocyte antigen–DR and CD34, but inversely associated with t(15;17), complex cytogenetics, FLT3–internal tandem duplication, NPM1 mutations, WT1 mutations, and expression of CD33 and CD15. Patients with ASXL1 mutations had a shorter overall survival than patients without, but the mutation was not an independent adverse prognostic factor in multivariate analysis. Sequential analyses showed that the original ASXL1 mutations were lost at relapse and/or refractory status in 2 of the 6 relapsed ASXL1-mutated patients studied, whereas 2 of the 109 ASXL1-wild patients acquired a novel ASXL1 mutation at relapse. In conclusion, AML bearing ASXL1 mutations showed distinct clinical and biological features. The ASXL1 mutation status can change during disease evolution in a few patients.

Mutations of nicotinamide adenine dinucleotide phosphate-dependent isocitrate dehydrogenase gene (IDH1) have been identified in patients with gliomas. Recent genome-wide screening also revealed IDH1 mutation as a recurrent event in acute myeloid leukemia (AML), but its clinical implications in AML are largely unknown. We analyzed 493 adult Chinese AML patients in Taiwan and found 27 patients (5.5%) harboring this mutation. IDH1 mutation was strongly associated with normal karyotype (8.4%, P = .002), isolated monosomy 8 (P = .043), NPM1 mutation (P < .001), and French-American-British M1 subtype (P < .001), but inversely associated with French-American-British M4 subtype (P = .030) and expression of HLA-DR, CD13, and CD14 (P = .002, .003, and .038, respectively). There was no impact of this mutation on patient survival. Sequential analysis of IDH1 mutation was performed in 130 patients during follow-ups. None of the 112 patients without IDH1 mutation at diagnosis acquired this mutation at relapse. In all 18 IDH1-mutated patients studied, the mutation disappeared in complete remission; the same mutation reappeared in all 11 samples obtained at relapse. We conclude that IDH1 is associated with distinct clinical and biologic characteristics and seems to be very stable during disease evolution.

Mutations in a variety of genes have been identified in MDS patients. Among them, mutations of additional sex combs-like 1 (ASXL1), found in 15-20% of MDS patients, have been identified as an independent poor prognostic factor. We previously demonstrated that C-terminal–truncating ASXL1 mutations (ASXL1-MT) inhibited myeloid differentiation and induced an MDS-like disease in mice after 1~2 years by inhibiting polycomb repressive complex 2–mediated methylation of histone H3K27 (Inoue et al. J Clin Invest. 2013). Given that ASXL1 mutations have been shown to be related to high-risk MDS or leukemic transformation, it is not clear how ASXL1-mutated MDS clones can transform into advanced MDS or AML. First, we examined genetic alterations in 368 WHO-defined MDS patients; ASXL1 mutations were detected in 64 of them (17.39%). Intriguingly, the patients with ASXL1 mutations had a significantly higher incidence of the concurrent SET binding protein 1 (SETBP1) mutation than those with the wild-type ASXL1 (6 out of 64, 9.38% vs. 2 out of 304, 0.66%, P=0.0005). Moreover, among ASXL1-mutated MDS patients, those harboring SETBP1 mutations had a higher incidence of leukemic transformation than those without (P=0.042), and MDS patients with both mutations had a significantly shorter overall survival compared to those without SETBP1 mutations (median, 10.5 vs. 22.5 months, P=0.046). In addition, we demonstrated that most SETBP1 mutations, such as D868N, occur in the PEST domain of the SKI homology region, preventing ubiquitination and subsequent proteasomal degradation. These results prompted us to investigate whether SETBP1 mutations play a critical role in the leukemic transformation of ASXL1-mutated MDS cells. In in vitro experiments, the expression of SETBP1-D868N enhanced myeloid colony formation of ASXL1-MT-transduced LSK cells, augmenting ASXL1-MT-induced differentiation blocking of 32Dcl3 cells. Of note, SETBP1-D868N collaborated with ASXL1-MT to induce AML after a short latency (median survival, 73 days) in a murine BMT model, while all mice expressing either ASXL1-MT or SETBP1-D868N survived for 6 months after transplantation (P To clarify the molecular mechanism leading to leukemic transformation, we first investigated the Pp2a-Akt pathway because SETBP1 protein has been shown to interact with SET oncoprotein, resulting in Pp2a phosphorylation and subsequent inhibition. Consistent with previous reports using overexpression systems of SETBP1 wild type protein (SETBP1-WT), BM cells of leukemic mice displayed phosphorylated Pp2a and Akt compared to those of the control mice. Administration of FTY720, a Pp2a activator, efficiently repressed the growth rate in vitro and slightly improved the survival of serially transplanted mice. Next, using RNA-seq and GSEA, we demonstrated that SETBP1-D868N enriched hematopoietic stem cell-related genes and posterior Hoxa genes. Chromatin immnoprecipitation assay showed that both SETBP1-WT and SETBP1-D868N interacted with the promoter regions of Hoxa9 and Hoxa10, raising the possibility that a gain-of-function mutant of SETBP1 enhances transcription of these genes, directly or indirectly. Moreover, GSEA indicated global repression of the TGF-β signaling pathway and reciprocal upregulation of the Myc pathway in leukemic mice. In conclusion, our data provide evidence for the role of SETBP1 mutations in leukemic transformation and suggest the resulting deregulated pathways as potential therapeutic targets to prevent disease progression in MDS. Disclosures Harada: Kyowa Hakko Kirin Co., Ltd.: Research Funding.

Introduction Acute myeloid leukemia (AML) is a highly heterogeneous disease with various cytogenetic and molecular abnormalities, some of which bear prognostic significance. Expression levels of some single microRNAs are influential for prognosis, but a system integrating several together and considering the weight of each should be more powerful. We sought to define a simple microRNA signature to predict prognosis in the patients. Method A cohort of 195 de novo AML patients who had cryopreserved marrow cells for study were subjected to global microRNA analysis. Analysis for overall survival (OS) was based on the 138 patients who received standard intensive chemotherapy (NTUH cohort). The AML cohort from the Cancer Genome Atlas (TCGA), which contains publically available data of microRNA and clinical information, serves as a validation cohort. To build a risk scoring system based on the global microRNA expression, we first analyzed the association between OS and the expression levels of individual microRNAs using univariate Cox proportional hazards regression model. MicroRNAs whose expression levels harbored top significance on OS (univariate Cox P < 0.005) were then analyzed with the multivariate Cox model. These microRNAs with independent survival significance (multivariate Cox P < 0.1) were selected to generate a risk scoring system, in which the expression of component microRNAs went through another round of multivariate Cox regression test to get beta values as weights for each microRNA. We also analyzed the global mRNA expression profiles from ours and TCGA cohort to sort out the physiologic pathways associated with high/low scores. Results Eleven microRNAs were significantly associated with OS by univariate Cox analysis (P < 0.005). After introducing the expression of these microRNAs into a multivariate Cox model, we identified high expression of hsa-miR-9-5p and hsa-miR-155-5p were independently associated with poor OS, while that of hsa-miR-203 had a trend of association with favorable OS. We constructed a risk scoring system: Risk = 0.4908 [Zhsa-miR-9-5p] + 0.2243 [Zhsa-miR-155-5p] - 0.7187 [Zhsa-miR-203], where the weights of microRNAs are beta values from multivariate Cox analysis and ZmicroRNA means the levels of specific microRNA expression after z-transformation. AML patients with higher scores had significantly shorter OS compared with those with lower scores in ours (median 13.5 months vs. not reached, P < 0.0001, Figure 1) as well as in the validation TCGA AML cohort (median 12.2 vs 26.4 months, P = 0.008, Figure 2). When restricting the analysis in our patients with a normal karyotype, the OS of patients with higher scores still fared worse (median 17.0 months vs. not reached, P = 0.006). Moreover, high score appeared to be an unfavorable prognostic factor independent of age, white cell count, cytogenetics, and gene mutation in both ours (HR=2.079, 95% CI 1.407-3.073, p Conclusion We present a simple and user-friendly 3-microRNA signature as a powerful prognostic factor for AML through multiple rounds of statistical analyses on our cohort and further validation by another independent patient group. Figure 1 Figure 1. Figure 2 Figure 2. Disclosures No relevant conflicts of interest to declare.

Background Ruxolitinib is a potent JAK1/JAK2 inhibitor that has demonstrated rapid and durable reductions in splenomegaly, improved MF-related symptoms and quality of life (QoL), and prolonged survival in 2 phase 3 studies comparing ruxolitinib with placebo (COMFORT-I) and best available therapy (COMFORT-II). However, no clinical trial in pts with MF had been conducted in Asian countries, and only a limited number of Asian pts or healthy volunteers had been enrolled in any ruxolitinib study. Methods This study was an open-label phase 2 study evaluating ruxolitinib in Asian pts with PMF, PPV-MF, or PET-MF who had palpable splenomegaly ≥ 5 cm below the costal margin and intermediate-2– or high-risk MF by the International Working Group for Myelofibrosis Research and Treatment (IWG-MRT) criteria. Pts received starting doses of ruxolitinib 15 or 20 mg twice daily (bid) based on baseline platelet count (100-200 or > 200 × 109/L, respectively); dose adjustments balancing safety and efficacy were allowed to titrate each pt to their most appropriate dose. The primary endpoint was met if the proportion of pts achieving ≥ 35% reduction in spleen volume from baseline at week 24 was ≥ 27.5% as measured by MRI/CT. Symptomatic response was assessed as a secondary endpoint using the 7-day modified MF Symptom Assessment Form (MFSAF) v2.0 total symptom score (TSS) and European Organisation for Research and Treatment of Cancer QoL Questionnaire Core 30 (EORTC QLQ-C30). The study was conducted in China (n = 63), Japan (n = 30), Korea (n = 17), and Taiwan (n = 10). The data cutoff date for this analysis was 7 June 2013. Results Overall, 120 pts were enrolled (PMF, n = 80; PPV-MF, n = 21; PET-MF, n = 19), and their baseline characteristics were as follows: median age, 61 years (range, 25-80 years); 51.7% female; 69.2% intermediate-2 and 30.8% high risk by IWG-MRT criteria; median palpable spleen size, 15 cm (range, 5-45 cm); median spleen volume, 2159 cm3; 55.8% of pts had prior exposure to hydroxyurea. The median follow-up was 8.44 months; 22.5% of pts discontinued treatment, primarily for adverse events (AEs; 9.2%) and disease progression (7.5%). The median duration of treatment was 8.44 months (range, 0.5-21.7 months), and the median daily dose was 20.64 mg/day in the 15 mg bid group (n = 46) and 36.11 mg/day in the 20 mg bid group (n = 74). All pts were evaluable for achievement of the primary endpoint, 101 pts remained on study and were evaluable at week 24, and 96 pts had nonzero scores on the MFSAF-TSS and were evaluable for a reduction from baseline. Most pts who had assessments at week 24 (91% [92/101]) had a reduction from baseline in spleen volume (Figure). The study met the primary endpoint, with 31.7% (38/120) of all pts achieving ≥ 35% reduction from baseline at week 24. Overall, 38.3% (46/120) of pts achieved ≥ 35% reduction from baseline in spleen volume at any time on study. As measured by the 7-day MFSAF, 49% (47/96) of pts achieved ≥ 50% reduction from baseline in TSS (median reduction, 47.2%). Pts experienced an improvement from baseline at week 24 in EORTC global health status/QoL (mean change, 5.2). The most common nonhematologic AEs (≥ 10%) regardless of relationship to study medication included diarrhea (25.8%), upper respiratory tract infection (17.5%), ALT level increased (15.0%), pyrexia (15.0%), AST level increased (13.3%), cough (11.7%), herpes zoster infection (11.7%), nasopharyngitis (10.8%), constipation (10.0%), gamma-glutamyl transferase level increased (10.0%), and headache (10.0%), and most were grade 1/2. Serious AEs were reported for 24.2% of pts, and 65.8% of all pts had grade 3/4 AEs. The most common new or worsening laboratory abnormalities were low hemoglobin (all grade 3, 55.7%), low lymphocyte (grade 3/4, 19.5%), low platelet (grade 3/4, 15.3%), and low ANC (grade 3/4, 7.6%) levels. AEs observed in this study were consistent with those observed in the 2 large phase 3 COMFORT studies. Six pts (5%) died on treatment or within 30 days of discontinuation. Summary/conclusions Findings from this study demonstrated that ruxolitinib was relatively well tolerated in Asian pts with MF and provided substantial reductions in splenomegaly and modest improvements in MF-associated symptoms. The AEs observed with ruxolitinib treatment in this study are consistent with those observed in the large phase 3 COMFORT studies, and there were no new AEs associated with ruxolitinib in Asian pts with MF. Disclosures: Okamoto: Novartis: Honoraria, Research Funding. Sirulnik:Novartis: Employment. Ruiz:Novartis: Employment. Amagasaki:Novartis: Employment. Ito:Novartis: Employment. Akashi:Novartis: Membership on an entity’s Board of Directors or advisory committees, Research Funding.

Introduction Homeodomain-only protein homeobox (HOPX) gene encodes a homeodomain protein without DNA-binding domains and functions as an adaptor protein to mediate transcriptional repression. HOPX is known to regulate cardiac development through interaction with serum responsive factor (SRF), thereby inhibiting SRF-dependent transcription either by interference of its DNA binding or recruitment of histone deacetylase. Recent studies have suggested that HOPX acts as a tumor suppressor gene since loss of its expression has been reported in several solid cancers. However the biological effects of HOPX in hematopoietic malignancies have not been explored. In this study, we aim to see the clinical and biological relevance of HOPX expression in acute myeloid leukemia (AML). Methods and materials We performed global mRNA arrays for 181 newly diagnosed AML patients in the National Taiwan University Hospital. There are also detailed demographic, clinical and genetic data for these patients. The HOPX gene expression levels extracted from the array data were analyzed for its clinical and biological relevance. We also tried to validate our findings by analyzing the public databases of AML. Results The 181patients were divided into two groups based on the median level of HOPX expression on the arrays. Patients with higher expression had higher platelet counts than those with lower expression (median, 59000/μL vs. 35000/μL, P=0.008). Higher HOPX expression was negatively associated with favorable karyotypes including t(8;21) and t(15;17). To investigate the association of gene mutations with HOPX expression in AML, we also performed a mutational screening for 17 genes. We found that patients with higher HOPX expression had significantly higher incidence of RUNX1 mutation (23.1% vs. 4.4%, P With a median follow-up of 33 months, patients with higher HOPX expression had shorter overall survival (OS) compared with patients with lower HOPX expression (median, 17 months vs. not reached, P=0.004). In multivariate analyses, higher expression of HOPX still represented a poor prognostic factor for OS independent of age, white blood cell counts, karyotype, NPM1 mutation, FLT3-ITD, CEBPAdouble mutation and RUNX1 mutation (P=0.021). Considering the hypothetical role of HOPX as a tumor suppressor in solid tumors, it seems surprising to see the negative impact on OS of high HOPX expression in AML. To be more assuring, we analyzed HOPX expression in another two large independent AML patient cohorts, TCGA and GSE12417_GPL96. We obtained the same results that higher HOPX expression was an unfavorable prognostic factor. Conclusions Higher expression of HOPX in AML patients was correlated with higher platelet counts and mutations in RUNX1 and IDH2, but negatively associated with favorable karyotypes such as t(8;21) and t(15;17) and CEBPA mutation or FLT3-TKD. Higher expression of HOPX appeared to be an independent unfavorable prognostic factor in our cohort, and its negative prognostic impact could be validated in another 2 large independent cohorts of AML. Further studies are needed to explore the biological significance of this gene expression in AML. Disclosures: No relevant conflicts of interest to declare.

Background Heritable mutation in GATA2, a zinc-finger (ZF) transcription factor crucial for hematopoietic stem cell proliferation and differentiation, was identified in the families with myelodysplastic syndrome related acute myeloid leukemia (MDS-AML). Recently, GATA2 mutations were found to be strongly associated with CEBPA double mutations (CEBPAdouble-mut) in AML, which define a distinct genetic entity of AML. However, the stability of the mutation during the clinical course remains unclear. In this study, we evaluated the clinical and biological features of AML with GATA2 mutation and analyze its sequential changes during the clinical follow-ups. Materials and Methods Mutation analysis of GATA2 exons 3-7 was performed by polymerase chain reaction and direct sequencing in 192 de novo AML patients. The association between GATA2 mutations and clinical features, chromosomal changes and genetic mutations were analyzed. Furthermore, sequential analyses of GATA2 mutation during the clinical course were performed in 375 samples from 138 patients. Results GATA2 mutations were seen in 27.4%, 6.7% and 1% of patients with CEBPAdouble-mut, CEBPA single mutation and CEBPA-wild type, respectively. Fourteen different missense GATA2 mutations, which were all clustered in the highly conserved N-terminal ZF-1 domain, were identified in 20 patients, most commonly A318V (n=4), followed by L321F (n=3) and A318T (n=2). GATA2 mutations were detected much more frequently in younger patients, and were closely associated with FAB M1 subtype, intermediate-risk cytogenetics, and expression of HLA-DR, CD7, CD15 or CD34 on leukemic cells. In contrast, GATA2 mutations were negatively associated with FAB M4 subtype and favorable-risk cytogenetics. A thorough mutation screening in 166 patients, including 15 GATA2-mutated ones, was performed to investigate the association between mutations of GATA2 and 17 other genes. The most common additional genetic aberrations in 15 GATA2-mutated patients at initial diagnosis were CEBPA mutation (n=14), followed by TET2 mutation (n=3) and NRAS mutation (n=2). Patients with GATA2 mutations had a significantly higher incidence of CEBPA mutation than those with GATA2-wild type (93.3% versus 34.4%, P Of the 154 AML patients undergoing conventional intensive induction chemotherapy, 124 (81%) patients achieved a complete remission (CR). Patients with GATA2 mutation had a higher CR rate and a trend of lower relapse rate compared with those with GATA2 wild-type (CR rate: 95% versus. 78.5%; relapse rate: 21% versus. 44.8%). With a median follow-up of 24.3 months (ranges, 0.1 to 150), patients with GATA2 mutation had significantly better overall survival (OS) and relapse-free survival (RFS) than those without GATA2 mutation (P=0.010 and P=0.033, respectively). Interestingly, among the subgroup of CEBPAdouble-mut patients, GATA2-mutated patients still had a trend of better OS and RFS than GATA2-wild type (median, not reached versus. 61 months, P=0.068 and not reached versus. 17 months, P=0.066, respectively). Multivariate analysis demonstrated that GATA2 mutation was an independent favorable prognostic factor for OS irrespective of age, white blood cell counts, cytogenetics and NPM1/FLT-ITD (HR: 0.0133, 95% CI: 0.018-0.978, P=0.047). In the serial studies of GATA2 mutations in 375 samples from 138 patients, including 14 GATA2-mutated and 124 GATA2-wild patients, all 14 GATA2-mutated patients lost the original mutations when first CR was achieved. Among them, four patients relapsed; two regained the original mutations and the other two lost them. On the other hand, two of the 124 GATA2-wild patients acquired a novel GATA2 mutation at first relapse and lost it at second CR. Interestingly, one of them regained the same GATA2 mutation at the second relapse. Conclusion AML patients with GATA2 mutations presented distinct clinical and biological features and a favorable prognosis in the total cohort. In the subgroup of patients with CEBPAdouble-mut, those with GATA2 mutations also had a trend of better OS and RFS compared with GATA2-wild patients. Sequential studies showed GATA2 mutation was not stable during disease evolution; it might be lost or acquired at disease progression, implying it was a second hit in the leukemogenesis of AML with CEBPA mutation. Disclosures: No relevant conflicts of interest to declare.