ALBERT

Description: Background: Many studies have indicated that histone deacetylases (HDAC) activity is always increased in a lot of human tumors, and inhibition of HDAC activity are promising new strategies in the treatment of cancers. Chidamide (CS055/HBI-8000), a novel histone deacetylases inhibitor (HDACi) of the benzamide class, is currently under clinical trials. Despite emerging information on the effect of chidamide in multiple cancers, little is yet known about mechanism of action, and there were few reports about this drug's effects on myelodysplastic syndromes (MDS). In this study, we aimed to investigate the antitumor activities of chidamide on MDS cell line SKM-1 and to explore the possible mechanism. Methods: We treated MDS cells with different concentrations of chidamide. The effect of chidamide on HDAC activity of MDS cells was studied by using a HDAC Fluorometric Activity Assay Kit. The induction of histone acetylation was confirmed by detecting acetylated histone H3 and H4 using Western blot analysis. The effect of chidamide on the proliferation of MDS cells was analyzed by Cell Counting Kit (CCK-8) assay. Apoptosis were detected by Annexin V/propidium iodide (PI) double-labeled cytometry. Cell cycle was analyzed by a PI method. The acetylation levels of genes promoterassociated histone H3 and H4 were examined by chromatin immunoprecipitation (ChIP) and quantitative real-time PCR. Quantitativereal-time PCR and Western blot were used to detect the expression of signaling pathway factors (SOCS3, JAK2, STAT3,Bcl-XL,Bcl-2 and Mcl-1). Results: Our results demonstrated chidamide suppressed MDS cells growth in a time- and dose-dependent manner, and induced cell apoptosis and cell cycle arrest at G0/G1phase. Chidamide was able to significantly inhibit the HDAC activity and increase the acetylated histoneH3 and H4 of MDS cells. ChIP analysis further indicated that chidamide induced acetylated histones accumulation in the promoter of SOCS3.Moreover, chidamide upregulated the mRNA and protein expression ofSOCS3, and also significantly downregulated JAK2/STAT3 signaling. Further, we identified reduced expression of STAT3 downstream targets with treatment of chidamide, including Bcl-XL, Bcl-2 and Mcl-1, which may explain the cytotoxic effects of chidamide on MDS cells. Conclusion: These results demonstrate that chidamide possesses significant cytotoxic effects on MDS cells mainly through histone modifications of SOCS3 and consequently JAK2/STAT3 signaling inhibition. Therefore, Our data provide rationale for clinical investigation of chidamide in MDS. Disclosures No relevant conflicts of interest to declare.

Description: Hypomethylating agents (HMA) (including decitabine and azacitidine) are considered standard of care for higher risk myelodysplastic syndrome (MDS). Clinical data showed only about 30% cases achieved complete response (CR) by decitabine. Mutations in the nucleophosmin-1 (NPM1) gene is one of the most common somatic mutations identified in de novo acute myeloid leukemia (AML) and have also been found in 1% to 5% of MDS patients although with different mutation locus (L287fs) when compared to that in AML (W288fs). Till now, the response and survival of NPM1-mutated MDS patients treated with HMA remains unknown. Here, we retrospectively analyzed higher risk MDSs who accepted decitabine therapy in our center. From December 2009 to July 2018, a total of 194 patients received decitabine induction treatment by 20mg/m2 intravenously for 5 consecutive days every 4-6 weeks. The median therapy course was four. Among them, twelve patients (6.2%) harbored NPM1/L287fs mutation. The median decitabine therapy cycle for the 12 NPM1 mutated patients was also four. To our interest, patients harboring NPM1 mutations achieved a relatively higher CR rate (6 of 12 cases, 50%) when compared to that of patients without NPM1 mutations (59 of 182 cases, 32.4%) , although without statistical significance (p = 0.304). Moreover, when the most common co-mutated genes DNMT3A (6 of 12 cases, 50%) (Figure 1a) was ruled out, patients harboring NPM1 mutation (DNMT3A wild type) achieved a CR rate of 83.3% (five of six), which is significantly higher than that of patients without NPM1 mutation (p = 0.018) (Figure 1b). Of note, when paired sequencing were analyzed, six patients who achieved CR by decitabine showed loss of mutated NPM1; One patients who achieved hematological improvement (HI) showed decreased variant allele frequency (VAF) of NPM1 mutation; Whereas two patients with no response (NR) showed unchanged NPM1 mutation (Figure 1d). Notably, a prolonged relapse-free survival (PFS) was observed in CR patients with NPM1 mutation and DNMT3A wild type (NPM1mut DNMT3Awt) even without any subsequent therapies after receiving 4-5 cycles of decitabine (Figure 1c). The median RFS of CR patients with NPM1mut DNMT3Awt was 66 months, which is significantly longer than that in patients without NPM1mutation (13.5M, p = 0.006) (Figure 1e). A remarkably prolonged median survival was also shown in patients harboring NPM1mut DNMT3Awt (median survival of 80M), which is significantly longer than that of patients without NPM1 mutation (18M) (p = 0.012) (Figure 1f). Interestingly, except with DNMT3A and PTPRD co-mutations, the response and survival of patients harboring NPM1 mutations treated with decitabine were favorable even when co-mutated with IDH2, NRAS, FLT3. In conclusion, NPM1 mutation with DNMT3A wild type defines a specific subgroup of MDS with a good response and prolonged survival by decitabine therapy, even when they were with some prognosis-poor co-mutations and without subsequent treatment. Enlarged sample of randomized controlled studies are needed to confirm our preliminary findings. Figure 1 Disclosures No relevant conflicts of interest to declare.

Description: Objective To observe and analyze the response characteristics based on revised IPSS (IPSS-R) cytogenetic risk stratification in patients with myelodysplastic syndromes (MDS) who received low-dose decitabine treatment. Patients and methods Eighty-seven MDS patients received decitabine treatment (15-20mg/M2/d×5/per course) with a median of 4 courses (range, 1-10). The clinical and cytogenetic response after treatment were observed to evaluate whether the IPSS-R cytogenetic risk stratification could predict treatment response. For those patients with abnormal karyotypes who achieved clinical complete response (CR), percentage of clonal cells in bone marrow (BM) was calculated by G-banding together with fluorescence in situ hybridization (FISH) to determine the minimal residual disease (MRD). In addition, the effect of cytogenetic response on overall survival (OS) was also analyzed. Results Sixty of 87 patients (69.0%) achieved treatment response including 25 cases (28.7%) with CR. For the 44 patients with abnormal chromosome, 27 cases (61.3%) achieved cytogenetic response including 18 with complete cytogenetic response (cCR). The patients carrying poor or very poor karyotypes presented better clinical and cytogenetic response than those with intermediate or good karyotypes. Among the patients with poor or very poor karyotypes, the ones carrying chromosome 7 aberrance showed better response than the others. Among 18 patients with abnormal karyotypes who achieved clinical CR, 4 cases presented cytogenetic PR or NR through G-banding analysis. FISH analysis revealed an over 5 % of clonal cells in BM in two patients who presented G-banding defined cytogenetic CR. In addition, longer median OS (24 months) were observed for patients who achieved cytogenetic response than those who did not (12 months) (P=0.007) Conclusion IPSS-R cytogenetic risk stratification could be used to predict the clinical and cytogenetic response to decitabine treatment in MDS patients. The predicting effect may be related to the chromosome 7 involvement rather than the number of abnormal karyotypes. FISH together with G-banding analysis should be available in determining MRD in MDS patients after treatment. Disclosures: No relevant conflicts of interest to declare.

Description: Background The combination of lenalidomide (LEN) and low-dose dexamethasone (LoDEX) is approved in China for the treatment of multiple myeloma (MM) patients (pts) who have received at least 1 prior antimyeloma treatment. The MM-021 China registration study demonstrated the efficacy and safety of LEN + LoDEX (Rd). This sub-analysis investigated the impact of the number of prior antimyeloma therapies on treatment outcomes. Methods MM-021 was a phase 2, multicenter, single-arm, open-label study. Relapsed and refractory MM (RRMM) pts (aged ≥ 18 yrs) were given LEN (25 mg/day on days 1-21) and LoDEX (40 mg/day on days 1, 8, 15, and 22) in 28-day treatment cycles until disease progression or discontinuation. Pts included in the pharmacokinetics cohort did not receive DEX on day 1, cycle 1. All pts received thromboprophylaxis during the study. The primary end-point was best overall response rate (ORR), defined as the percentage of pts who achieved a best response of at least partial response. Secondary end-points included progression-free survival (PFS), time to progression (TTP), overall survival (OS), and safety. Data were analyzed according to the number of therapies that pts had received prior to study screening: 1-2, 3-4, or 〉 4. Results The analysis cut-off date was January 4, 2013, with a median follow-up of 17.6 mos. All pts in the intent-to-treat (ITT) population (N = 199) were included in the safety analysis, and 187 pts were included in the efficacy-evaluable (EE) population. At the cut-off date, 42 pts had completed treatment and 157 had discontinued. Overall, the median age of pts was 59.0 yrs (range 35-81) and 62.8% were male. The majority of pts had advanced disease (85.9% had Durie-Salmon stage III MM); 40.7% of pts (ITT population) had received 〉 4 prior anti-myeloma therapies; 33.2% had received 3-4, and 26.1% had received 1-2. Most pts had received prior treatment with thalidomide (THAL; 68.8%) or bortezomib (BORT; 63.8%) (Table 1). After a median treatment duration of 8.3 mos (range 0.9-24.8) or 9 treatment cycles (range 1-27), the ORR was 47.6% in the overall EE population, and highest in pts who had received 1-2 prior therapies (Table 2). Median OS, PFS, and TTP were longer in pts who had received 1-2 prior therapies compared with those who had received 3-4 and 〉 4 prior therapies, and compared with the overall EE population (Table 2). In the safety population, the most common grade 3-4 treatment-emergent adverse events (TEAEs) were anemia (26.1%), neutropenia (25.1%), thrombocytopenia (14.6%), pneumonia (13.1%), leukopenia (9.5%), and decreased neutrophil count (8.5%). In general, grade 3-4 TEAE rates were lower in pts who had received 1-2 prior therapies (60%), and comparable in pts who had received 3-4 (71%), 〉 4 prior therapies (75%), and the overall safety population (70%). There were 2 reports of grade 3-4 peripheral neuropathy. AEs resulted in discontinuation of LEN in 5.8% (n = 3), 10.6% (n = 7) and 9.9% (n = 8), of pts who had received 1-2, 3-4 and 〉 4 prior therapies, respectively. Conclusion Rd is an effective treatment option for Chinese RRMM pts who have relapsed after one or more prior therapies, including THAL and/or BORT. More robust efficacy and higher ORR was observed for Rd in patients who had received 1-2 prior therapies compared to those who had received additional lines of treatment. The tolerability of Rd was similar in heavily and less heavily pretreated pts. Discontinuations were infrequent, even in heavily pretreated pts who had received 〉 4 prior therapies. Disclosures: Zhang: Celgene Corporation: Employment, Equity Ownership. Wortman-Vayn:Celgene Corporation: Employment, Equity Ownership. Mei:Celgene: Employment, Equity Ownership. Hou:Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees; J & J: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Description: Abstract LBA-3 Mutations in the transcription factor genes, RUNX1 and CEBPA, can lead to an autosomal dominant familial predisposition to MDS/AML. Using a candidate gene approach, we have detected domain specific heterozygous mutations in the GATA2 gene in 4 MDS/AML families which predispose to MDS/AML. The same novel heterozygous T354M missense mutation was observed in 3 families and a 355delT mutation in 1 family, all with multigenerational transmission of MDS and/or MDS/AML. Importantly, these genetic variants segregate with all affected members in each of the families. The 2 mutated threonine residues are in 5 consecutive highly conserved threonine residues at the DNA-binding, protein-protein interacting second zinc finger (ZF2) of GATA2. Neither these mutations, nor any other variants in the GATA2 coding sequence, were seen in a population screen of 695 normal individuals. Haplotype analysis suggests that the T354M mutation has multiple ancestral origins. While mutations in RUNX1 and CEBPA, can also lead to familial predisposition to MDS/AML, these patients with GATA2 mutations are unique in that there is no obvious pre-MDS or pre-leukaemic phenotype such as thrombocytopenia (RUNX1) and eosinophilia (CEBPA) in predisposed carriers. Most patients in these families have had a rapid disease course “appearing out of the blue” leading to death, with a variety of ages of onset from teenagers to early 40s. Yet remarkably, there are still asymptomatic carriers in their 60s. One of these carriers, and his 2 children, has had bone marrow prophylactically stored over 15 years ago in case of disease onset. No pathogenic GATA2 coding sequence changes were found in 268 sporadic MDS/AML patient samples. Additionally, GATA2 mutations were not found in germline samples from 35 other families predisposed to AML and various other hematological malignancies. Both the T354M and 355delT mutants appear to localize appropriately to the nucleus and maintain at least some DNA binding in electrophoretic mobility shift assays. We used the known murine Gata3 ZF2 structure bound to DNA to model the effects of the observed mutations and demonstrated that the T354 residue does not contact DNA but makes polar contact with the adjacent threonines, and via its amino group, with C349 which coordinates the zinc atom. Replacement of the T354 side-chain with the bulky methionine moiety may affect the zinc contacts and is predicted to alter the overall structure of this ZF2. In contrast, 355delT will shorten the conserved threonine string which is predicted to impact on the orientation and position of L359 which directly contacts DNA. Thus, 355delT is likely to have an effect on DNA binding. Luciferase reporter assays indicate that T354M and 355delT greatly reduce the transactivation ability of GATA2 on multiple response elements, impacting on downstream target genes such as RUNX1 and CD34. Of note, T354M shows a markedly lesser synergistic effect than wildtype (WT) GATA2 with PU.1 on the CSF1R promoter. Competition assays show that these mutations may be acting in a dominant negative fashion in some biological contexts. In stable promyelocytic HL-60 cell lines expressing regulatable GATA2 (WT or T354M), T354M allows proliferation to proceed even under stimulus to differentiate with all-trans retinoic acid. Microarray studies indicated that the down regulation of proapoptotic BCL-xS by T354M, but not WT, may be responsible for this phenotype. GATA2 is considered to be a hematopoietic “stemness” gene, highly expressed in haematopoietic stem cells and is required for megakaryocyte and mast cell production. GATA2 is down regulated during myeloid differentiation and forced overexpression prevents such differentiation. Discovery of GATA2 mutants in MDS/AML predisposed families provides new tools for probing the mechanism of GATA2 induced leukemogenesis, and possibly also for clarifying its role in maintenance of stemness. Our findings highlight the power of investigating familial predispositions to cancer identifying specific mutations with unique biological effects. They have immediate implications for diagnostic genetic testing, and longer term therapeutic implications through identification of drugable biological pathways such as apoptosis. The poor outcome associated with these mutations may suggest that an aggressive strategy is appropriate in the treatment of affected individuals in families found to be carrying GATA2 mutations. Disclosures: No relevant conflicts of interest to declare.

Description: We investigate the frequency of the human leukocyte antigen DR15 (HLA-DR15) allele in patients with myelodysplastic syndromes (MDS). We used polymerase chain reaction-sequence-specific primers (PCR-SSP) to detect HLA-DR15 in the peripheral blood of patients with MDS(n = 76) and healthy controls (n = 227). The frequency of HLA-DR15 in MDS patients (40.8%) was significantly higher than in controls (13.7%; P 〈 0.01). The diagnoses of refractory anemia/refractory anemia with ring sideroblasts (RA/RARS) accounted for 77.4% (24/31) and 62.2% (28/45) of the DR15-positive and the DR15-negative patients, respectively (difference not statistically significant). Although no statistically significant difference was observed, some trends were observed: IPSS low-risk MDS (IPSS score, ≤1) accounted for 80.6% of the DR15-positive patients compared to 64.4% among the DR15-negative patients. However, the difference between the numbers of DR15-positive and DR15-negative patients with chromosomal abnormalities was not statistically significant. Nevertheless, poor risk chromosome abnormalities (according to IPSS), were present in only 1 DR15-positive patient, while such abnormalities were present in 8 DR15-negative patients. In addition, the proportions of DR15-positive and DR15-negative patients with more than 5% blasts in marrow were 19.4% and 31.1%, respectively. Peripheral blood pancytopenia occurred in 51.6% of DR15-positive, and in 40.0% of DR15-negative patients. Although the HLA-DR15 allele appeared to be present more frequently in patients less than 60 years of age, this association was not significant. The frequency of HLA-DR15 was significantly higher in patients with MDS than in healthy controls suggesting the possibility that HLA-DR15 is associated with an enhanced susceptibility to develop MDS. The fact that HLA-DR15 was predominantly noted in patients with RA/RARS and low IPSS scores, suggested that HLA-DR15 might be associated more with bone marrow failure and less with leukemic transformation. clinical/experimental characteristics in HLA-DR15 positive or negative MDS patients Cohort HLA-DR15 positive(n=31) HLA-DR15 negative(n=45) P value RA/RARS(case/%) 24/31(77.4) 28/45(62.2) 0.161 Low risk (IPSS≤1) (case/%) 25/31(80.6) 29/45(64.4) 0.126 Karyotype abnormal(case/%) 13/31(41.9) 18/45(40.0) 0.866 Poor chromosome(case/%) 1/31(3.2) 8/45(17.8) 0.117 Blast〉5%(case/%) 6/31(19.4) 14/45(31.1) 0.253 Pancytopenia(case/%) 16/31(51.6) 18/45(40.0) 0.317 Male patients(case/%) 17/31(54.8) 25/45(55.6) 0.951 age(

Description: Abstract 4703 Objective: The purpose of this study was to investigate the therapeutic potential of Human umbilical cord mesenchymal stem cells (HUCMSCs) from normal donors for preventing acute GVHD following allogeneic bone marrow transplantation (BMT). Methods: In this study, a new method of separating and culturing HUCMSCs was used. The human umbilical cord tissue was digested by collagenase II for 2h. And after being passaged to P3, more HUCMSCs could be obtained. In the control group, after being lethally irradiated, DBA/2(H-2Kd) mice were transferred bone marrow (BM) and splenocytes (SC) from C57BL/6 (H-2Kb) mice. Recipients in the HUCMSCs-treated group were adoptive transferred HUCMSCs, BM and SC at day 0 and were transferred only HUCMSCs at day 3 again. The two groups were compared in weight, survival, histopathological specimens, lymphocyte subgroups and serum cytokine analysis. Results: In vitro, IFN-γ treated HUCMSCs have a strong inhibitory effect on the proliferation of CD4 + T cells (P0.05). IDO is involved in the immunosuppression of HUCMSCs. In the HUCMSCs-treated group, 50% of the mice survived over 30 days after BMT, but in the control group all mice died within 18 days. The mice treated with HUMSCs exhibited light symptoms of aGVHD after day 14. There were higher IFN-γ and IL-12 levels by day 7 in serum of mice that received HUCMSCs compared to those without HUCMSCs-treatment, while the IL-4 levels showed no significant difference between the two groups. The proportion of CD3+NK1.1+NKT cells in splenocytes of HUCMSCs-treated group is higher in day 21 compared with in day 7. Conclusion: Using the new method of digesting human umbilical cord tissue by collagenase II for 2h, we obtained stable and pure HUCMSCs. IDO is involved in the immunosuppression of HUCMSCs. After the xenogeneic transplantation of HUCMSCs to the aGVHD model of mice, HUCMSCs can regulate cytokines such as IFN-γ, IL-12 to increase CD3+NK1.1+NKT cells. Disclosures: No relevant conflicts of interest to declare.

Description: Background DHX9(Asp-Glu-Ala-His box helicase 9) is considered to play a key role in many biological processes and cancer development. However, the effect of DHX9 mutation and the main function is not fully understood in myelodysplastic syndromes (MDS). Objective The objective of this study is to investigate the frequency of DHX9 mutations and their relationship with clinical characteristics in MDS. Methods Next generation sequencing was used to determined the DHX9 mutations and other recurrent genes mutations in 320 MDS patients. The effect of DHX9 mutations or combination with other genes mutations on patients' survival was analyzed. The association of DHX9 mutations with clinical characteristics of MDS was also studied. In addition, the effect of DHX9 on tumor biological features was evaluated in vitro. Results 1. DHX9 mutations were detected in 10.94% of MDS patients(35/320). 42.9% of these mutation were del(c.306_308), 31.4% were splicing mutations (c.674-4A〉G; c.2512+8C〉A) and the rest (25.7%) were missense mutation. In these patients with DHX9 mutations, 24(68.6%) had concomitant occurrence with other mutations such as ANKRD11, TET2, ASXL1, TP53 and U2AF1 (Fig.1A). 2. The patients with DHX9 mutations especially sole mutations had significantly superior survivalcompared with those without mutations (Fig.2B). The patients with DHX9 mutations also had superior survivalcompared with those with genes mutations with poor prognosis, such as DNMT3A/RUNX1/ASXL1, IDH1/TP53/U2AF1, PTPRD/ANKRD11, even those mutations with good prognosis such as TET2 and SF3B1 (Fig.2C, 2D and 2E). 3. We also analyzed the difference in clinical features between the patients with and without DHX9 mutations (Table 1). Obviously, the patients with DHX9 mutations exhibited more severe BM failure and reduced Tc1/Tc2 polarization. 4. The quantitive PCR revealed that the patients with DHX9 mutations had lower expression of DHX9 mRNA than those without DHX9 mutations. The MDS patients had significantly higher expression of DHX9 than normal controls. No difference was observed in DHX9 expression between the MDS patients with DHX9 mutations and normal controls (Fig.2A). 5. In vitro experiments,knockdown of DHX9 induces increased cell apoptosis and inhibits cell growth in myeloid cell lines (SKM-1, K562 and HEL cells) (Fig.2B and 2C). Knockdown of DHX9 significantly enhanced the expression of apoptotic proteins (Fig.2D). Conclusion DHX9 mutations are novel recurrent molecular aberrations in MDS and closely related to bone marrow failure. Figure 1. The distribution of DHX9 mutations and the effect of DHX9 mutations or combination with other genes mutations on patients' survival. Figure 1. The distribution of DHX9 mutations and the effect of DHX9 mutations or combination with other genes mutations on patients' survival. Figure 2. Comparison between patients with or without DHX9 mutations Figure 2. Comparison between patients with or without DHX9 mutations Figure 3. The mRNA expression of DHX9 in MDS and the effect of DHX9 knockdown in myeloid cell lines Figure 3. The mRNA expression of DHX9 in MDS and the effect of DHX9 knockdown in myeloid cell lines Disclosures No relevant conflicts of interest to declare.

Description: Uveal melanoma is the most common intraocular malignancy in adults and results in the death of 50% of the patients. Plasminogen activators (PA) are believed to facilitate tumor metastasis by promoting invasion of tissue barriers. The present study explored the possibility of preventing the metastasis of intraocular melanomas by disrupting plasminogen activator function through gene transfer. A replication-deficient adenovirus vector was used for the in vivo transfer of plasminogen activator inhibitor type 1 (PAI-1) cDNA. Intraocular injection of an adenovirus vector (AdCMV-PAI-1) expressing plasminogen activator inhibitor-1 resulted in: (1) the transduction of more than 95% of human and murine uveal melanoma cells in the eyes of nude mice; (2) a 50% reduction in the number of animals developing liver metastases; and (3) a 78% reduction in the metastatic tumor burden in animals that eventually developed metastases. In other experiments intravenous injections of AdCMV-PAI-1 resulted in transduction of normal liver cells and culminated in a sharp reduction in the incidence of metastases and a significant prolongation of host survival. The results support the feasibility of disruption of PA function through gene transfer as a therapeutic strategy for preventing metastases and prolonging host survival.

Description: Background To analyze whether some distinct gene mutations could predict treatment response to Hypomethylation Agent---Decitabine. Patients and Methods Targeted next-generation sequencing was performed on reported 30 recurrently mutated genes for 106 MDS patients before they accepted Decitabine therapy. For those who presented satisfactory response (CR) or poor response (NR or PD), their gene sequencing were repeated after Decitabine therapy to analyze the alteration of the gene mutation. Results The overall response rate was 67.0%, with 26.4% patients (28 cases) achieving CR. The median survival of patients who achieved CR was longer than those who just achieved NR/PD (22 months VS 14 months, p =0.021). Among the 14 TP53 mutant patients, ten achieved CR (71.4%). Moreover, two of 3 BCOR mutant patients (66.7%) and three of 5 KIF20B mutant patient (60.0%) also achieved CR. Zero of the patients who were with IDH1/2(n=11), GATA2 (n=5), SETBP1 (n=5), EZH2 (n=3) or CEBPa (n=1) mutations could get CR response (Figure1). On the other hand, total five of the 8 PTPRD mutant patients (62.5%) and five of 11 ASXL1mutant patients did not responded to Decitabine. In addition, 16 among the 28 CR patients accepted the target sequencing after the stop of decitabine therapy. Ten of the 16 patients showed decreased number of mutant genes (Table1). Besides, the TP53 mutation was completely fade away in five of 7 patients after Decitabine treatment (Table 2). Finally, the TP53 mutant and wild type of MDS patients achieved comparable overall survival, suggesting decitabine treatment could significantly alter the prognostic impact of adverse genetic alterations. Conclusion Some gene mutation (specially TP53) seemed predictive for Decitabine response. Further studies with large samples are needed to identify it. Table 1. The number of mutant genes on CR patients before and after Decitabie therapy Sample Number of mutations response Before After Sample 586 3 2 CR Sample 967 3 2 CR Sample 1761 4 2 CR Sample 1619 2 3 CR Sample 1864 7 4 CR Sample 1854 3 1 CR Sample 1818 3 2 CR Sample 1522 2 4 CR Sample 2038 2 2 CR Sample 2055 2 1 CR Sample 702 3 1 CR Sample 828 2 0 CR Sample 1361 0 0 CR Sample 1002 2 1 CR Sample 1917 1 2 CR Sample 1154 0 0 CR Table 2. Status of TP53 mutation after hypomethylating agents in CR patients. Sample Before After response Sample 586 TP53/8/D242H TP53-WT CR Sample 967 TP53/6/R174L TP53-WT CR Sample 1864 TP53/8/R244H TP53/8/R244H CR Sample 1854 TP53/4/W91 TP53-WT CR Sample 2038 TP53/8/F231S TP53/8/F231S CR Sample 2055 TP53/6/R196* TP53-WT CR Sample 1002 TP53/8/R234H TP53-WT CR Disclosures No relevant conflicts of interest to declare.