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We aimed to improve the outcome of t(8;21) acute myeloid leukemia (AML) in the first complete remission (CR1) by applying risk-directed therapy based on minimal residual disease (MRD) determined by RUNX1/RUNX1T1 transcript levels. Risk-directed therapy included recommending allogeneic hematopoietic stem cell transplantation (allo-HSCT) for high-risk patients and chemotherapy/autologous-HSCT (auto-HSCT) for low-risk patients. Among 116 eligible patients, MRD status after the second consolidation rather than induction or first consolidation could discriminate high-risk relapse patients (P = .001). Allo-HSCT could reduce relapse and improve survival compared with chemotherapy for high-risk patients (cumulative incidence of relapse [CIR]: 22.1% vs 78.9%, P < .0001; disease-free survival [DFS]: 61.7% vs 19.6%, P = .001), whereas chemotherapy/auto-HSCT achieved a low relapse rate (5.3%) and high DFS (94.7%) for low-risk patients. Multivariate analysis revealed that MRD status and treatment choice were independent prognostic factors for relapse, DFS, and OS. We concluded that MRD status after the second consolidation may be the best timing for treatment choice. MRD-directed risk stratification treatment may improve the outcome of t(8;21) AML in CR1. This trial was registered at http://www.chictr.org as #ChiCTR-OCH-12002406.

Background The frequency of invasive fungal disease (IFD) has increased in recent two decades and has emerged as an important cause of life-threatening infections in immunocompromised patients, especially in those who have undergone allogeneic hematopoietic stem cell transplantation (HSCT). Empirical antifungal therapy has been the standard of care used to decrease the number of deaths due to IFD among neutropenic patients who have persistent or recurrent fever despite broad-spectrum antibacterial treatment. However, about two thirds of these patients may be potentially exposed to unnecessary empirical antifungal treatment with associated potential toxicity and considerable financial burden. It was demonstrated that high-resolution computerized tomography (HRCT) had early predictive value for fungal infection, and the major signs on chest CT scans generally precede the positive outcome of serum galactomannan test. It was also shown that the diagnosis-based treatment strategy only based on HRCT results could reduce more than a half use of antifungal agents in HSCT patients who had persistent febrile neutropenia. Thus, we would like to explore the feasibility of this new strategy for hematological patients with IA in China. Method This was a prospective and single-arm study. Up to now, 24 neutropenic patients after intensive chemotherapy or HSCT with high risk factors for IFD from three hospitals were enrolled. After recruitment, HRCT of thorax will be conducted within 24h. If HRCT shows any new changes suspicious of fungal infection, including halo sign, cavity, air-crescent sign, or other non-specific signs, voriconazole would be given intravenously for two weeks, followed by oral voriconazole. Six weeks after initiation of antifungal therapy, the outcome was evaluated by clinicians according to the patients' imagining and microbiological evidences and clinical conditions, and complete or partial responses were defined as successful outcome of antifungal therapy. Result The median age of this population was 38.5 years (range from 19 to 78). Four of 24 patients were the recipients of HSCT, and the others received intensive chemotherapy. There were four patients had history of IFD, and 7 take fluconazole orally for antifungal prophylaxis. At the beginning of antifungal therapy with voriconazole, 12 had non-specific infiltrates on pulmonary HRCT, 8 had dense lesions with halo sign, and 4 had cavity. At the end of six-week follow-up, 5 patients were diagnosed with possible IA, 6 with probable IA and 1 with proven IA. The total successful rate of antifungal therapy with CT-diagnostic-driven strategy was 50.0% (12/24). Notably, efficacies of the antifungal treatment in patients with specific IA signs on pulmonary HRCT were significant higher than that in patients with non-specific signs (75.0% vs. 25.0%, P=0.043). Conclusion The CT-diagnostic-driven antifungal strategy was effective and suitable for patients with hematological malignancies. Disclosures No relevant conflicts of interest to declare.

We studied the impact of risk stratification–directed interventions for minimal residual disease (MRD) on relapse and disease-free survival (DFS) prospectively in 814 subjects with standard-risk acute leukemia receiving allotransplantation in first or second complete remission. A total of 709 subjects were MRD− after transplantation (Group A); 105 subjects were MRD+, 49 received low-dose IL-2 (Group B), and 56 received modified donor lymphocyte infusion (DLI) with or without low-dose IL-2 (Group C). Posttransplantation immune suppression for GVHD was also modified based on MRD state. The cumulative risk of relapse was significantly less and DFS was significantly better in subjects in Group C than in subjects in Group B (P = .001 and P = .002, respectively), but was not different from subjects in Group A (P = .269 and P = .688, respectively). Multivariate analyses confirmed that MRD state and modified DLI were significantly correlated with relapse (P = .000, odds ratio [OR] = 0.255 and P = .000, OR = 0.269) and DFS (P = .001, OR = 0.511 and P = .006, OR = 0.436, respectively). These data suggest that risk stratification–directed interventions with modified DLI in patients with standard-risk acute leukemia who are MRD+ after transplantation may improve transplantation outcomes.

The relative merits of allogeneic hematopoietic stem cell transplantation (allo-HSCT) and imatinib for chronic myelogenous leukemia in the accelerated phase (AP-CML) have not previously been evaluated. This cohort study was designed to compare the outcomes of imatinib (n = 87) versus allo-HSCT (n = 45) for AP-CML. A multivariate analysis of the total population revealed that a CML duration ≥ 12 months, hemoglobin < 100 g/L, and peripheral blood blasts ≥ 5% were independent adverse prognostic factors for both overall survival (OS) and progression-free survival (PFS). Both treatments resulted in similar survival in low-risk (no factor) patients, with 6-year event-free survival (EFS), OS, and PFS rates of more than 80.0%. Intermediate-risk (any factor) patients showed no difference in EFS and OS, but 6-year PFS rates were 55.7% versus 92.9% (P = .047) with imatinib versus allo-HSCT, respectively. Among high-risk (at least 2 factors) patients, imatinib was by far inferior to allo-HSCT, with 5-year EFS, OS, and PFS rates of 9.3% versus 66.7% (P = .034), 17.7% versus 100% (P = .008), and 18.8% versus 100% (P = .006), respectively. We conclude that allo-HSCT confers significant survival advantages for high- and intermediate-risk patients with AP-CML compared with imatinib treatment; however, the outcomes of the 2 therapies are equally good in low-risk patients. All trials were registered with the Chinese Clinical Trial Registry (www.chictr.org) as CHiCTR-TNC-10000955.

Allogeneic hematopoietic stem cell transplantation (allo-HCT) is an effective, even curative, treatment for patients with high-risk hematologic malignancies. Transplantation from haploidentical donors (haplo-HCT) has been applied for the treatment of hematologic malignancies within the past 2 decades. Bone marrow (BM), G-CSF-primed peripheral blood stem cells (PBSCs), G-CSF-primed BM (G-BM) or the combination of PBSCs and G-BM can serve as stem cell sources for allo-HCT. The optimal source of stem cells in cases of haplo-HCT without ex vivo TCD under myeloablative conditioning is not yet clear. Therefore, we initiated a study of unmanipulated haplo-HCT from PBSCs (haplo-PBSCT) for the treatment of high-risk hematologic malignancies. In this report, we analyzed 89 adult patients who received consecutive haplo-PBSCT to evaluate the efficacy and safety of this transplantation procedure. PATIENTS AND METHODS Eighty-nine patients received consecutive haploidentical allo-PBSCT between July, 2007 ¨C June, 2014 at the Chinese PLA General Hospital, Beijing, China (Table 1). PBSCs were freshly isolated and infused into the recipients. The conditioning regimen consisted of Bu (3.2 mg.kg-1.d-1 intravenously, days -10 to -8), Carmustine, 250 mg.m-2, day -5), cytarabine (4 g.m-2.d-1, days -7 to -6), cyclophosphamide (60mg kg-1.d-1, days -4 to -3), and ATG (Thymoglobuline, rabbit; 2.5 mg.kg-1.d-1, days -5 to -2). All transplant recipients received CsA, mycophenolate mofetil, and short-term methotrexate for GVHD prophylaxis. "High-risk'' hematologic malignancies were defined as: 1) AL with the [t(9;22)(q34;q11)], Flt3-ITD mutation, mixed lineage leukemia genes and complex cytogenetics regardless of disease stage; 2) AML-CR1 after 3 or more cycles of induction, ALL-CR1 after 4 weeks of induction or AL-CR1 with positive MRD after 2 cycles of consolidation; 3) AL beyond CR2 or in non-remission (NR) regardless of cytogenetics, or CML beyond CP1; and 4) T cell lymphoblastic lymphoma in CR and T cell lymphoma resistant to chemotherapy or autologous transplantation. The endpoint of the last follow-up for all surviving patients was January 31, 2015. RESULTS Sustained myeloid engraftment with full donor chimerism was achieved in 89 patients (100%) at a median of 16 (10 - 26) days. Eighty patients (89.9%) achieved platelet recovery in a median of 28 (10 - 207) days. The occurrence of GVHD was showed in Fig 1. The 3-year of cumulative incidence of transplant-related mortality was 23.4% ± 5.4%. Non-remission status prior to transplant was found to be significantly correlated with relapse (P = 0.006, odds ratio [OR] = 3.17), leukemia-free survival (P = 0.013, OR = 2.48) (Fig. 2) and overall survival (P = 0.03, OR = 2.27). CONCLUSION The results described rapid and complete neutrophil engraftment, a low incidence of grade 3-4 GVHD and promising survival in patients with high-risk hematologic malignancies. It demonstrated the reliability of G-CSF-primed PBSCs as a graft source in unmanipulated haplo-HCT under myeloablative conditioning. Table 1. Patient and donor characteristics Cases % Gender, n (%) Male 69 77.5 Age, y, median(range) Patient 40 y, n (%) 38(9-61) Hematologic malignancy, n (%) AML 51 57.3 CR1 CR2* 23 3 NR*/beyond CR2 23/1 ALL 20 22.5 CR1 CR2 10 7 NR 3 CML 5 5.6 CP1* 2 AP/CP2 1/2 Lymphoma 13 14.6 CR 5 Resistant 8 Donor/recipient relationship, n (%) Parent 47 52.8 Sibling 26 29.2 Child 12 13.5 Lateral relative 4 4.5 No. of HLA antigens (A/B/DR) mismatched, n(%) 1 18 20.2 2 25 28.1 3 46 51.7 Second HCT 9 10.1 Graft: MNC (108/kg) 11.04 (5.64-36.46) CD34+ (106/kg) 5.83 (2-23.73) Figure 1. Acute and chronic GVHD. (A) CI (Cumulative Incidence) of grade 2-4 (continuous line) and grade 3-4 (dotted line) acute GVHD. (B) CI of total (continuous line) and moderate to severe (dotted line) chronic GVHD. Figure 1. Acute and chronic GVHD. (A) CI (Cumulative Incidence) of grade 2-4 (continuous line) and grade 3-4 (dotted line) acute GVHD. (B) CI of total (continuous line) and moderate to severe (dotted line) chronic GVHD. Figure 2. Disease-free survival according to disease status. Figure 2. Disease-free survival according to disease status. Disclosures No relevant conflicts of interest to declare.

Allogeneic hematopoietic stem cell transplantation (allo-HCT) is the only effective, even curative treatment for refractory/relapsed AML patients. Unmanipulated haploidentical HCT (haplo-HCT) resulted in encouraging outcomes for treatment of hematologic malignancies and become an alternative option in case of lacking HLA matched sibling donor (MSD). Unmanipulated haplo-HCT from G-CSF mobilized bone marrow and peripheral blood stem cell (PBSC) has shown similar results as that from MSD-HCT in leukemia. Here, we report the results of a cohort study on the efficacy and toxicity of haplo-PBSCT compared with MSD-PBSCT for treatment of refractory/relapsed AML. PATIENTS AND METHODS Among 419 newly diagnosed AML patients, 69 patients relapsed during CR1 and were planned to receive allo-HCT after re-induction. The order of preference of donors was MSD, matched unrelated (HLA 10/10 or 9/10 loci matched), or haploidentical donor. Thirty patients received haplo-PBSCT and 13 patients MSD-HCT (July, 2007 ~ June, 2014) at our unit. There was no difference of the characteristics of demography, disease or transplantation between these two groups (Table 1). High-resolution DNA techniques were used to evaluate the HLA-A, B, DRB1, DQB1, and C loci. Donors were treated with rhG-CSF (5 mg.kg-1.day-1) for consecutive days. The PBSCs were collected on day 5 - 6 and infused on the day of collection. The conditioning regimen consisted of Bu (9.6 mg.kg-1, intravenously, days -10 ~ -8), Carmustine, (250 mg.m-2, day -5), cytarabine (8 g.m-2, days -7 ~ -6), CY (120 mg kg-1, days -4 ~ -3), and ATG (rabbit; 10 mg.kg-1, days -5 ~ -2). MSD-HCT patients had the same conditioning regimen without ATG. All transplant recipients received cyclosporine A, mycophenolate mofetil, and short-term methotrexate for GVHD prophylaxis. The endpoint of the last follow-up for all surviving patients was June 30, 2015. RESULTS Sustained myeloid engraftment with full donor chimerism was achieved in both groups (100%) at a median of 16 (10 - 26) days. Twenty-six patients (86.7%) in haplo-PBSCT group and all patients in MSD-PBSCT group achieved platelet recovery. There was no difference of the cumulative incidence of acute GVHD grade 2-4 (Fig. 1), chronic GVHD (20% vs 33.3%, P=0.581), transplantation-related mortality (TRM) (16.7% vs 0%, P = 0.121), relapse (33.3% vs 38.5%, P = 0.578, Fig 2) between haplo-PBSCT and MSD-PBSCT group. Donor age of 41yr and older was an independent risk factor for inferior leukemia-free-survival (27.8% vs 37.2%, P = 0.004). CONCLUSION In this cohort study, haplo-PBSCT showed similar outcomes in patients with refractory/relapsed AML compared with MSD-PBSCT. It suggested the feasibility of G-CSF-primed PBSC as a graft source in unmanipulated haplo-HCT under myeloablative conditioning, which was effective and tolerable for treatment of poor risk leukemia. Table 1. Characteristics of patients and donors Haploidentical donor Matched sibling donor P value Cases % Cases % Gender, n (%) Receipt Male 22 73.3 8 61.5 0.485 Donor Male 22 73.3 7 53.8 0.292 Age,y, median(range) Patient ≤40 y, n (%) 21 70 6 46.2 0.178 Donor ≤41 y, n (%) 13 43.3 5 38.5 1.000 AML, n (%) 1.000 CR2 5 16.7 2 15.4 NR/beyond CR2 25 83.3 11 84.6 Time to transp 0.51 ≥7m 14 46.7 8 61.5 Conditioning Regimen, n (%) 0.675 BuCy 22 73.2 9 69.2 TBIcy 4 13.3 1 7.7 FB 4 13.3 3 23.1 CD34+ in graft (106/kg) 0.499 ≥4.77 17 56.7 5 41.7 Figure 1. Figure 1. Figure 2. Figure 2. Figure 3. Figure 3. Disclosures No relevant conflicts of interest to declare.

Objective To retrospectively evaluate the effect of the third party umbilical cord blood on haplo-identical hematopoietic stem cell transplantation. Methods From June 2012 to May 2015, 125 leukemia patients were enrolled, including 41 cases of ALL, 62 cases of AML, 12 cases of MDS, 7 cases of CML-BP, 2 cases of acute mixed leukemia and 1 case of Mother cell dendritic cell tumor. Inclusion criteria: 1) AL patients; 2) halpo-identical HSCT; 3) 3/6 matched cord blood was available. Patients were divided into two groups, ie. group A (HSCT, n=65) and group B (HSCT plus umbilical cord blood transfusion group, n=60). Myeloablative conditioning regimens consisted of BuCy, TBI/FLAG, TBI/Cy, and FLAG that followed by reduced-intensified BUCY. The median dose of mononuclear cells in group A and B were 8.58×108/kg and 9.01×108/kg, respectively. The median dose of CD34+ cells for transfusion in each group were 3.67×106/kg and 2.94×106/kg, respectively. The dose of grafted UCB MNCs and CD34+ cells for group B were 3.5×107/kg and 2×105/kg, respectively. All patients received cyclosporineA, MMF and methotrexate for GVHD prophylaxis. The endpoints of this study were hematological engraftment, incidence of acute and chronic GVHD, incidence of relapse, transplant-related mortality(TRM), non-relapse mortality(NRM), Overall survival(OS) and Disease-free survival(DFS) in each group. Results The median follow-up time was 17(3-29) months in group A and 18(3-35) months in group B. Patients in group A reached a sustained ANC of more than 0.5*109/L at a median of 11 days, whereas 14 days in group B. Platelet more than 20*109/L occurred at a median of 19 days in group A, whereas 17 days in group B (P= .4). The rate of aGVHD was not significantly different in the two groups, 56.9% in group A and 48.3% in group B (P= .21). The accumulative incidence of II-IV grade aGVHD was 35.4% in group A and 30% in group B (P= .42). The incidence of chronic GVHD was 79.2% in group A and 71% in group B (P= .47). The incidence of extensive type was lower in group B, 69.2% Vs 35%, P=0.09. The incidence of CMV was lower in group B, 80% Vs 60% (P= .01). The accumulative incidence of EBV was lower in group B, 35.4% Vs 3.3% (P Disclosures No relevant conflicts of interest to declare.

Objective To retrospectively evaluate the results of allogeneic halpo-identical hematopoietic stem cell transplantation for high-risk leukemia. Methods From June 2012 to January 2015, total 60 patients with high-risk leukemia were enrolled, including 18 cases of ALL, 37cases of AML and 5 case of CML-BP. Including criterions: 1) ≥CR1; 2) relapse within 6 months after remisson. The average leukemia burden was 53% in bone marrow. All patients received HLA haplo-identical stem cells transplantation from parent or sibling donors. Myeloablative conditioning regimens consist of 7cases of BuCy, 26 cases of TBI/FLAG, 15 cases of TBI/Cy, and 12 cases of FLAG that followed by reduced-intensified BUCY. All patients received cyclosporine A, MMF and methotrexate for GVHD prophylaxis. Analyzed outcomes were hematological engraftment, incidence of acute and chronic GVHD, incidence of relapse, and nonrelapse mortality (NRM), Overall survival (OS) and Disease-free survival (DFS). Results The median mononuclear cells and CD34+ for transfusion were 9.08(7.02-24.4)*108/Kg and 3.42(0.8-12.1)*106/Kg. All 60 patients achieved stable engraftment. The median time of ANC≥0.5*10^9/L was 16 (8-23) days. And for platelet ≥20*10^9/L, the median was 22 (8-150) days. 38 patients developed acute GVHD, the accumulative incidence of aGVHD was 66.4%, the accumulative incidence of II-IV grade aGVHD was 35%, and the accumulative incidence of III-IV grade aGVHD was 15%. 26 patients developed cGVHD (12 patients extensive, 14 patients limited), the accumulative incidence of cGVHD was 88.2% and for extensive type, the accumulative incidence was 67.4%. The accumulative incidence of CMV infection was 54.1%, and the accumulative incidence of EBV infection was 16.3%. 10 patients developed virus cystitis. The number of Bacterial and fungal infected patients were 51 and 27, respectively. The median follow-up time post transplantation was 11(1-36) months, 14 patients relapsed and the accumulative incidence of relapse was 27%. For AML, ALL and CML-BP patients, the accumulative incidence of relapse were 26.6%, 34.8% and 0%, respectively. The median follow-up time post transplantation was 11months, 21 patients died and the main causes were relapse (11 cases), infection (5 cases), cGVHD (2 cases) and diffuse alveolar hemorrhage (3 cases). Among 60 patients, 39 patients survived. The one-year and two-year accumulative incidences of OS were 61.8% and 49.5%, respectively. The one-year and two-year accumulative incidences of DFS were 53.8% and 47.8%, respectively. For AML, ALL and CML-BP patients, the two-year accumulative incidence were 52.6%, 34.4% and 66.7%, respectively. The non-relapse mortality was 10. The one-year and two-year accumulative incidences of NRM were 19.4% and 28.4%, respectively. Conclusion Our clinical results have shown that the salvaged HSCT is a promising modality for treatment of high-risk AL with high leukemia burden. Disclosures No relevant conflicts of interest to declare.

The major complication of allogeneic HSCT-graft-versus-host disease (GVHD)-remains lethal and limits use of this important procedure, especially after unmanipulated haploidentical HSCT. Several studies have provided evidence that universal addition of corticosteroids for prophylaxis of GVHD can reduce the risk for acute GvHD grade II-IV in HLA-matched transplantation. However, corticosteroid, a non-specific immunosuppressive agent, may also contribute to high rates of infections. Our previous data suggest that the ratio of CD4/CD8 in allografts from haploidentical donors can stratify patients into high-risk and low-risk ones who will develop GVHD after transplantation. Recently, we indicated that low-dose of methylprednisolone (MP, 0.5 mg/kg/day) might be a well-tolerated, effective and inexpensive regimen in combination of MTX for therapy of GVHD, suggesting that low-dose corticosteroid may be used for the prophylaxis of GVHD without increasing infection. To investigate whether risk-stratification directed prophylaxis strategy can reduce the incidence of GVHD and improve survival in a hemogenous patient population who underwent unmanipulated haploidentical HSCT, we performed a prospective, randomized, controlled, clinical trial. A total of 228 patients were enrolled in this trial. All of the patients completed the study and were stratified as high-risk (n=145) and low-risk arms (n=83) according to the ratio of CD4/CD8 in allografts. Patients of the high-risk arms were randomly assigned in a 1:1 ratio to additional low-dose glucocorticoid prophylaxis group (Group A, n=72) and control group (GroupB, n=73). The groups were balanced with respect to patient and donor characteristics. Our results showed that the cumulative incidence of grade II-IV acute GVHD on day 100 was 20.9%±4.8% in Group A, which was comparable to Group C (25.5%±4.8%, P=0.430) and both of which were significantly lower than that of Group B (48.1%±5.9%, P＜0.001). In addition, the onset time of grade II-IV acute GVHD was 25 (16-50) days, 15 (9-57) days, and 21 (10-58) days, respectively in Group A, Group B, and Group C (P＜0.05, Group A vs. Group B or Group C). There were no significant difference in grade Ⅲ-IV acute GVHD among these three groups. The ratio of patients who developed glucocorticoid refactory acute GVHD and treated with basiliximab (anti-CD25 antibody) were 13.9% (10/72), 17.8% (13/73), and 22.9% (19/83), respectively, in Group A, Group B, and Group C, there is a trend that the incidence of basiliximab treated patients in Group C is higher than that of Group A (P=0.109). The median time for myeloid engraftment in Group A was 11 days (range: 10-21 days), which was significantly faster that those of Group B (13 days, range from 10 to 33 days, P＜0.05) and Group C (13 days, range from 10 to 33 days, P＜0.05). The median time for platelet engraftment in Group A was 12 days (range: 10-22 days), which was significantly faster that those of Group B (17 days, range from 6 to 255 days, P＜0.01) and Group C (19 days, range from 8 to 260 days, P＜0.01). In addition, risk-stratification directed prophylaxis with additional low-dose of MP did not increase the incidence of CMV, EBV reactivation, PTLD, relapse and TRM, as well as delay immune recovery after unmanipulated haploidentical HSCT. The 100 day cumulative incidence relapse and transplant-related mortality was not significantly different among patients in Group A, Group B, and Group C, respectively. The 100 day probabilities of LFS and OS were comparable among these three patient groups. In conclusion, we for the first time demonstrated that risk-stratification directed prophylaxis for GVHD with additional low-dose of MP could significantly decrease the incidence and delay the onset of grade II-IV acute GVHD without increasing infections and delaying immune recovery. Our data indicated that addition of glucocorticoid early after unmanipulated haploidentical transplantation could also accelerate hematopietic recovery [This study was registered at http://clinicaltrials.gov/ NCT01607580]. Disclosures No relevant conflicts of interest to declare.

Prolonged thrombocytopenia is a common complication after allogeneic hematopoietic stem cell transplantation(allo-HSCT),which is associated with a high mortality and poor prognosis. The aim of this study was to assess the impact of the CD8+CX3CR1+ T cells on the development and maturation of megakaryocytes in patients with the prolonged thrombocytopenia after allo-HSCT in order to identify the risk factors related to thrombocytopenia after allo-HSCT. The changes in CD8+ T cells and their homing receptors CX3CR1, CXCR4 and VLA-4 in bone marrow of patients( N=89) with and without (N=94 ) prolonged thrombocytopenia following allo-HSCT and the impact of activated CD8+ T cells on apoptosis and ploidy of megakaryocytes in vitro ware determined. The percentage of CD8+CX3CR1+ T cells was significantly higher in prolonged thrombocytopenia patients than control (P Disclosures: No relevant conflicts of interest to declare.

Introduction Leukemia relapse is the most common cause of treatment failure after allogeneic hematopoietic stem cell transplantation (allo-HSCT). The biological mechanism of relapse is still not completely clear. Allo-HSCT can be considered as a kind of immunotherapy directed toward malignant hematologic disease. Confirmation the correlation between clinical relapse and specific subset of T cells and further elucidating the immune mechanism behind this phenomenon would be beneficial to explore new methods of adoptive immunotherapy. Accumulative evidence showed that regulatory T cells (Tregs) might be involved in immune escape mechanism and associated with the failure of host to trigger efficient immunological antitumor response. Recently, a kind of non-traditional CD4+ CD25–CD69+ T cells was found to be involved in disease progression in tumor-bearing mouse models and cancer patients. In this study, we attempted to define whether this subset of T cells was related to leukemia relapse after allo-HSCT and also demonstrate the potential immune regulatory mechanism behind this phenomenon. Methods Twenty-nine patients with malignant hematological disease treated with non-T-cell-depleted allo-HSCT at the Peking University Institute of Hematology from November 2009 to April 2011 including patients undergoing hematological relapse (n=22) and with detectable minimal residual disease (MRD, n=7) were selected as the initial subjects in this study. The other fifty-six patients who received allo-HSCT from October 2009 to July 2010 were also enrolled for prospective study. The bone marrow of the initial 29 subjects was collected at the time of hematological relapse or detecting MRD. The MRD status of those 56 patients was examined at regular time points: +30 day (d), +60d, +90d, +180d, +270d, +360d. Bone marrow samples from patients at above time points were collected for the MRD examination and counting of CD4+CD25-CD69+ cells by flow cytometry (FCM). Results The frequency of CD4+CD25-CD69+ T cells in healthy donors’ bone marrow was 2.79% (range, 2.11-4.94%). However, the frequency of this subset of T cell was significantly increased in patients with detectable MRD (7.60%, range, 4.53-9.14%, P=0.008), or undergoing hematological relapse (12.96%, range, 8.62-20.49%, P0.05). The incidence of MRD+ or relapse in high frequency of CD4+CD25-CD69+ T cells group (>7%) was distinctly higher than that of low frequency of CD4+CD25-CD69+ T cells group at +60d, +90d and +270d after transplant. However, our preliminary data indicated that CD4+CD25-CD69+ T cells might not display immune regulatory function via cytokine secretion. Conclusions This study gave the first clinical evidence of correlation between non-traditional CD4+CD25-CD69+ T cells and leukemia relapse after allo-HSCT and would be beneficial to explore new methods of adoptive immunotherapy. Further research related to regulatory mechanism behind this phenomenon would be necessary. Disclosures: No relevant conflicts of interest to declare.

Background The prognosis of Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) has been greatly improved in the modern era of imatinib. Nevertheless, relapse is still a major cause of treatment failure in human Ph+ALL. Leukemia-initiating cells (LICs) are presumed to be responsible for relapse in leukemia. Therefore, we conducted a study to identify the candidate LICs that are responsible for disease progression and its clinical significance in patients with Ph+ALL. Aims To investigate the leukemia-initiating and self-renewal capacities of CD34+CD38-CD58- cells and determine the prognostic significance of CD34+CD38-CD58- phenotype in patients with Ph+ALL treated in Peking University Institute of Hematology. Methods The leukemia-initiating potential and self-renewal capacity of the sorted CD34+CD38-CD58-, CD34+CD38-CD58+,CD34+CD38+CD58- and CD34+CD38+CD58+ compartments were investigated in vivo using sublethally irradiated and anti-mouse CD122 monoclonal antibody conditioned NOD/SCID mice by intra-bone marrow–injection. Furthermore, we prospectively analyzed whether the identified CD34+CD38-CD58- compartment at diagnosis correlates with minimal residual disease (MRD) after therapy and clinical outcomes in 63 adult patients (18-60 years) with de novo Ph+ALL. Results Xenotransplantation of the sorted CD34+CD38-CD58- cells led to a repopulation of human B-ALL in primary and secondary recipient mice, which were phenotypically and clonally derived from the original Ph+ALL patients analyzed by flow cytometry, as well as quantitative real-time RT-PCR and fluorescence in situ hybridization for leukemia-specific cytogenetic abnormalities. Furthermore, the candidate CD34+CD38-CD58- LICs phenotype at diagnosis (n=16) significantly correlated with a lower complete remission rate and higher MRD frequency monitored by BCR-ABL mRNA levels in BM of Ph+ALL patients. Additionally, it directly correlated with higher cumulative incidence of relapse (CIR, 60% ± 1.97% vs. 15.51% ± 0.30%, P=0.002) and unfavorable disease-free survival (DFS, 33.75%±12.64% vs. 71.31%±7.17%, P=0.009) at 3-year. The CD34+CD38-CD58- group exhibited a higher rate of BCR-ABL mutations conferring higher level imatinib resistance than the other group (43.75% vs. 17.02%, P=0.04). Multivariate analyses revealed that CD34+CD38-CD58- phenotype at diagnosis was an independent risk factor for relapse (HR=4.35, P=0.009) and DFS (HR=3.38, P=0.008) in adult Ph+ALL. Summary/Conclusion Both the xenotransplantation data as well as the clinical correlation studies show that CD34+CD38-CD58- compartment enrich for leukemia-initiating cells in adult Ph+ALL. CD34+CD38-CD58- phenotype at diagnosis independently correlates with an adverse prognosis, which promises to be an efficient tool for relapse prediction and risk-stratification treatment in adult Ph+ALL patients. Acknowledgments This work was supported by grants from National Natural Science Foundation of China (grants no. 30800483&81230013) and Beijing Municipal Science and Technology Program (grant no.Z111107067311070). Disclosures: No relevant conflicts of interest to declare.

Although cerebral complications and causes after allogeneic hematopoietic stem cell transplantation (allo-HSCT) were well documented, assessment of incidence rates and risk factors of intracranial hemorrhage (ICH) following allo-HSCT are less discussed. The clinical data of 1461 consecutive patients undergoing allo-HSCT in Peking University Institute of Hematology from January 2005 to June 2011 were retrospectively analyzed. Among these patients, 44 developed intracranial hemorrhage (ICH) and matched 176 patients control subjects were accrued. ICH was verified by computed tomography (CT) scan in all patients. Among the 1461 patients, 44 patients (3.0 %) developed ICH, including 29 patients (65.9%) with multiple location hemorrhage, 4 patients (9.1 %) with subdural hematoma (SDH), 8 patients (18.2%) with subarachnoid hemorrhage (SAH), and 3 patients (6.8%) with other hemorrhage in the brain parenchyma. The median time of appearance for ICH was 129 days (1-450). Survival after 6 year was significantly reduced in patients who developed ICH complications compared with control (47.1% vs. 75.7%,p Disclosures: No relevant conflicts of interest to declare.

Background Although acute myeloid leukemia (AML) with t (8; 21) translocation generally belongs to the favorable-risk AML subtypes, relapse occurs in about 40% of cases and long-term (>5years) survival less than 50%. KIT-mutation (KIT+) and minimal residual disease (MRD) levels have been demonstrated as two most important risk factors in several retrospective studies. Until now, only two prospective studies (Our AML05 trial; French CBF-2006 trial) have assessed their respective prognostic values (Zhu HH, et al. Blood 2013; 121:4056; Jourdan E, et al. Blood 2013; 121:2213). We found both KIT+ and MRD were independent risk factors for relapse, but Joundan et al found only MRD rather than KIT+ was sole prognostic factor for relapse in multivariate anaysis. Both studies did not perform a comprehensive subgroup analysis combining the two factors, and risk-adopt postremission treatment might also affect this assessment. Therefore, we performed a subgroup analysis combining KIT mutation and MRD in a prospective protocol AML05 to answer which is more important to predict outcomes of t(8;21)AML. Methods From July, 2005, to Jan, 2013, 114 patients with t (8; 21) AML after achieving complete remission were included in this analysis. KIT mutations in exons 17 and 8 were screened using the direct sequencing method. MRD was detected using quantitative PCR to detect the RUNX1/RUNX1T1 transcript. MRD-positive (MRD+) was defined as < 3 log reduction of RUNX1/RUNX1T1 transcript from baseline after second consolidation therapy. Sixty-two patients received high-dose cytarabine-based consolidation chemotherapy (CT) or autologous hematopoietic stem-cell transplantation (auto-HSCT), and 52 patients received allogeneic HSCT (allo-HSCT). Results When receiving CT/auto-HSCT as postremission treatment, KIT+ patients (n=19) had a higher 3 year cumulative incidence of relapse (CIR) than KIT-patients (n=43) (94.4% vs. 38.2%, p Conclusions Both KIT status and MRD level were important to predict relapse of t (8;21) AML. KIT+ patients hold a very high relapse risk. Disclosures: No relevant conflicts of interest to declare.

Background Exposure to non-inherited maternal antigen (NIMA) in fetal and neonatal life has a lifelong immunological consequence. In haploidentical transplantation, the mismatched haplotype of the donor can originate from either the mother or the father. The aim of this prospective study is to investigate the effects of NIMA and non-inherited paternal antigen (NIPA) on transplant outcomes in patients who underwent unmanipulated haploidentical blood and marrow transplantation (HBMT). Methods Two hundred and eleven patients with hematological disease, including AML, ALL, CML, MDS, SAA, and others, who received haploidentical blood and marrow allgrafts were enrolled in this study. The stem cell source was G-CSF mobilized BM combined with PB. The conditioning regimen was modified BUCY plus ATG with 10mg/kg in total dosage. MTX, CSA, and MMF were used for prophylaxis of graft-versus-host disease. Results The median patient follow-up was 343 days (range, 7-573 days). The median time for neutrophil and platelet engraftment was 12 days (range 7-25 days) and 16 days (range 6-410 days), respectively. The cumulative incidence of grade 2-4 actue GVHD at day 100 after HBMT was 41.7%±3.8% The cumulative incidence of chronic GVHD at 1 year was 53.4%±4.1%. The 1-year probability of relapse, TRM, LFS, and OS at 1 year was 11.3%±2.3%, 8.3%±1.9%, 79.6%±3.0%, and 85.0%±2.8%, respectively. Among the 211 patients, multivariate analysis showed that high risk patients had a high relapse rate (HR: 3.699, 95%CI, 1.598-8.565, P=0.002) and low LFS (HR: 2.452, 95%CI, 1.322-4.546, P=0.004). Duration from diagnosis to transplantation (more than 6 months vs. less than or equal to 6 moths) was associated with a high incidence of TRM (HR: 3.175, 95%CI, 1.251-8.059, P=0.015). Young recipient age (HR: 0.969, 95%CI, 0.946-0.993, P=0.012) were associated with a low incidence of grade 2-4 actue GVHD. Multiple analysis also showed that patients who received allografts from NIMA mismatched donor and father donor had lower incidences of grade 2-4 actue GVHD compared to those of patients receiving allografts from mother (HR: 0.576, 95%CI, 0.334-0.996, P=0.048, and HR: 0.378, 95%CI, 0.126-1.137, 0.087, respectively). For subgroup patients who received allografts from sibling donors, multivariate analysis showed that sibling transplantations mismatched for NIMA had a significantly lower incidence of grade 2-4 acute GVHD than those with NIPA mismatched donors (HR: 0.257, 95%CI, 0.083-0.796, P=0.018). No effects of NIMA mismatch on relapse, TRM, LFS, and OS were found in the current study. Conclusions Our results suggest that HBMT from a NIMA mismatched donor can offer low indicence of grade 2-4 acute GVHD. In unmanipulated haploidentical settings, mother donor transplantation may be associated with high incidence of grade 2-4 acute GVHD. These data suggest a NIMA mismatched donor not a mother donor should be preffered as donor for unmanipulated haploidentical blood and marrow transplantation. Disclosures: No relevant conflicts of interest to declare.

Background The introduction of rituximab has improved the complete remission(CR) rate of EBV-associated posttransplant lymphoproliferative disease(PTLD), thus the recurrence of PTLD becomes the main cause affecting long-term survival, which is closely related with the reestablishment of immune functions. Unfortunately, PTLD happens generally at the early stage of transplants and the reconstitution of immunocompetence needs for 3-5 years in the recipients of allo-HSCT. In this study, a sequential therapeutic strategy that based on rituximab followed by adoptive cellular therapies (G-CSF mobilized donor lymphocyte infusion (DLI) or EBV-specific cytotoxic T lymphocyte infusion (EBV-CTL)) was evaluated for decreasing relapse of PTLD. Methods Fifty-two patients with EBV-PTLD were enrolled in this prospective study. Once PTLD was diagnosed,immunosuppressants would be withdrawn in a stepwise fashion (ie, total dose reduced by 20%/week)if the condition of the patient was acceptable. The rituximab-based treatments (rituximab alone or combined with chemotherapy) were administrated based on PTLD histopathology and the blood cells counts. After CR or 2 cycles of rithuximab-based treatments, DLI or EBV-CTL therapy would be performed in this cohort. The rituximab-based treatments would be discontinued once patient obtained CR, and DLI would be performed once Monthly till GVHD occurred or for a total of 4 doses and EBV-CTL infusion would be performed every two weeks till GVHD occurred or for a total of 8 doses . Results After 2 cycles of the rituximab-based treatments, 37 patients obtained complete remission (CR), 8 obtained partial remission (PR), and 7 no remission (NR), including 4 died of PTLD progression. The CR rate of 2 cycles of rituximab-based treatments was 71.2%. After rituximab-based treatments combined with the adoptive cellular therapies, 9 obtained CR and 2 died of PTLD progression in 11 patients who did not achieve CR within 2cycles of rituximab-based treatments. The CR rate of 2 cycles of rituximab-based treatments combined with cellular therapies was 88.5%. Seven patients experience acute GVHD (aGVHD) (grade I in 1 and grade II in 6) and 8 chronic (cGVHD) (limited cGVHD in 5 and extensive cGVHD in 3) in 39 patients underwent a median 4 doses of DLI. One patient experienced grade II aGVHD and 2 limited cGVHD in 8 patients underwent a median of 7 doses of EBV-CTL. There were no differences in incidence of aGVHD(P=1.000) and cGVHD(P=1.000) between the patients received DLI and CTL. Within a median follow-up of 632 (range, 21 to 1651) days, one patient experienced PTLD relapse, and the 4 year cumulative incidence of PTLD relapse and primary malignancy relapse was 5.3%±5.1% and 6.2±4.3%, respectively. The 4 year cumulative overall survival (OS) after PTLD and disease(PTLD)-free survival were 66.2%±7.1% and 65.9±7.3%, respectively. Conclusions Rituximab-based treatments combined with the adoptive cellular therapies might elevate PTLD CR rate, and decrease the relapse in the recipients of allo-HSCT. Disclosures: Liu: It was supported by 863 Program (No. 2011AA020105), National Public Health Grand Research Foundation (Grant No. 201202017): Research Funding; It was supported by National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China(11A72121174): Research Funding.

Introduction Acute myeloid leukemia (AML) with t(8;21) is a heterogeneous disease. The dynamic patterns of AML1-ETO transcript levels during treatment and clinical outcome of patients vary greatly. Our AML05 trial revealed that minimal residual disease (MRD)status and treatment strategy were independent risk factors for outcome and that risk stratification treatment directed by MRD may improve the outcome of t(8;21) AML in CR1 (Blood 2013; 121:4056). As for pretreatment parameters, c-KIT mutation is a well-established adverse predictor on survival. However, a subset of t (8;21) AML patients without c-KIT mutation still showed poor clinical outcome. The prognostic value of WT1 transcript levels at diagnosis in AML has been investigated and the results were controversial. We wondered if WT1 expression associated with outcome in t (8;21) AML patients. Methods A total of 101 patients were included. They all were eligible cases who enrolled into AML05 trial from June 2005 to December 2012, and had available bone marrow samples at diagnosis. After 1 or 2 induction therapy and 2 cycles of intermediate-dose cytarabine-based consolidation therapy, fifty-seven patients continued cytarabine-based consolidation chemotherapy or received autologous-hematopoietic stem-cell transplantation (auto-SCT) and were defined as CT group, the remaining 44 patients received allogeneic SCT (allo-SCT) and defined as SCT group.WT1 and ABL transcript were tested by real time quantitative PCR, and WT1 transcript levels were calculated as WT1copies/ABL copies in percentage. The upper limit of normal bone marrows (NBMs) was 0.5%. c-KIT mutations in exon 8 and 17 were screened by direct sequencing. Results The median follow-up time was 25 (6-93) months for 73 alive patients. The cumulative incidence of relapse (CIR) at 3 years was 35.3%. The 3-year disease free survival (DFS) and overall survival (OS) rates were 57.2% and 62.8%, respectively. The median WT1 transcript levelsssof all patients were 9.1% (0.02%-99.3%). c-KIT mutation was detected in 31 patients. Receiver operating characteristics (ROC) curves revealed that WT1 transcript levels of 5.0% (1-log increase compared to the upper limit of NBM) were the best cutoff values to discriminate patients with different outcome. WT1 transcript levels of ≤5.0% were significantly associated with c-KIT mutation (23/42 vs 8/59, P0.05). In CT group, patients with WT1≤5% (n=19) had significantly higher CIR rate at 3-year, lower 3-year DFS and OS rate than those with WT1>5% (n=38), respectively (89.5% vs 27.9%, P5% and c-KIT mutation (+) (all P >0.05, Figure 1). Therefore, they were merged into one group (n=24). Thus, patients with WT1≤5% and/or KIT mutation (+) had significantly higher CIR rate at 3-year, lower 3-year DFS and OS rate than those with WT1>5% and c-KIT mutation (-) (n=33) in CT group, respectively (89.4% vs 27.4%,P5%) and treatment (chemotherapy/auto SCT vs allo-SCT) instead of other pretreatment parameters were independent prognostic factors for relapse (hazard ratio (HR) 0.20, 95% CI 0.093¨C0.44; 0.096, 95% CI 0.033¨C0.28. all P Conclusion Less than 1-log increase of WT1 transcript levels at diagnosis is a strong predictor on poor outcome in patients with t (8;21) AML, and allo-SCT could significantly improve outcome of such patients. Grant Support Bejing Municipal Science & Technology Commission(Z111107067311070) and Nature Science Foundation of China (81170483). Disclosures: No relevant conflicts of interest to declare.

Background Results from single institutions had shown that compared with busulfan plus cyclophosphamide (BuCy) conditioning, limiting tissue damage by myeloablative busulfan plus fludarabine (BuFlu) conditioning might decrease cytokines release, leading a lower incidence of the graft-versus-host disease (GVHD) in allogeneic hematopoietic stem cell transplantation (allo-HSCT). In our prospective, multicenter and parallel-group study, further comparison was made of the incidences and severities of GVHD following BuCy and BuFlu myeloablative conditioning regimens in patients undergoing allo-HSCT for AML in first complete remission (CR1), and analyzed plasma cytokines before and after the conditioning. Methods A total of 148 patients with AML-CR1 undergoing allo-HSCT were enrolled into BuCy (busulfan1.6mg/kg, iv q12 hours, -7 ∼ -4d; cyclophosphamide 60 mg/kg.d, -3 ∼ -2d) or BuFlu (busulfan 1.6 mg/kg, iv q12 hours, -5 ∼ -2d; fludarabine 30 mg/m2.d, -6 ∼ -2d) group between January 2007 and January 2013. For patients enrolled between January 2012 and January 2013, plasma concentrations of IL-6, IL-1β, TNF-α, CXCL-10 and IL-17A before and after conditioning were measured by Enzyme-linked immunosorbent assay (ELISA) and compared between the two groups. Regimen-related toxicity (RRT), incidences and severities of acute and chronic GVHD, and overall survival were compared between the two groups. Results Of the 148 patients enrolled in the study, the data of 142 cases were used to determine the endpoints in the intent-to-treat population (72 in BuFlu group and 76 in BuCy group). The levels of TNF-α and IL-6 were significantly higher after the conditioning (5.60±4.40 vs 8.94±5.50 and 2.19±1.24 vs 6.06±12.16 pg/ml, P Conclusion In this report, the incidences and severities of acute GVHD as well as chronic GVHD were similar between BuFlu and BuCy regimen in AML-CR1 patients undergoing allo-HSCT. Disclosures: Liu: National Natural Science Foundation of China (Grant No.81000231, No.81270647) and Science and Technology Program of Guangzhou of China (11A72121174).: Research Funding; It was supported by 863 Program (No. 2011AA020105), National Public Health Grand Research Foundation (Grant No. 201202017): Research Funding.

Introduction HLA-mismatched/haploidentical stem cell transplantation (SCT) is a feasible therapeutic option for advanced hematologic malignancies patients who lack an HLA-matched related or unrelated donor. The effect of NK alloreactivity in HLA haploidentcial SCT is still under debate and in particular in transplantation for chronic myeloid leukemia (CML) the data are very limited and with conflicting outcome.The goal of this study was to explorethe predictive roles of missing self model in our HLA-mismatched/haploidentical transplantation without T-cell-depletion in vitro in chronic myeloid leukemia patients, and to develop a simple algorithm on the basis of recipients and donor HLA-C and HLA-Bw4 gene content that can be used today to identify HLA-mismatched donors who will associated withbetter prognosis in T cell¨Creplete transplants. Methods We studied the HLA genotype of 78 donor-recipient pairs and the KIR genotype of their donor, who underwent unmanipulatedHLA-mismatched/haploidentical transplantation without T cells depletion in vitro during 2003-2009 in our center. To applythe missing ligand model, the first step was to divide ourdonor-recipient pairs into 2 groups according to the number of KIR ligand indonor and recipient, ie, 3 KIR ligands (“without missing self”) versus fewer than 3(“with missing self”). Meanwhile, to apply the KIR ligand-ligand model, donors who were classified as NK alloreactive against their recipientstermed KIR ligand mismatched donors throughout, possessedHLA class I KIRligand(s) which were missing in the recipients. Results Among the 78 pairs of donor-recipients, 65 and 13 recipients receivedHLA¨Cmismatched/haploidentical transplants from “with missing self (R-L mismatch)” and “without missing self (R-L match)” donors, respectively. Using Ligand-ligand model, 59 and 19 recipients received haploidentical transplantation from “KIR ligand matched (L-L match)” and “KIR ligand mismatched (L-L mismatch)” donors, respectively. In contrast to Perugia's KIR ligand-ligand mismatched model or Handgretinger's KIR missing self model between donor-recipient pairs, we found that the 10-year disease free survival(DFS) rate were higher in patients received transplantation from “without missing self (R-L match)” donorscompared with those from “with missing self (R-L mismatch)” (92.3±7.4% vs. 55.2%±6.2%, p=0.024, Figure1A) , especially in high risk CML patients (100% vs. 37.2%±8.6%, p=0.029, Figure1B). When combined the above missing self model and Ligand-ligand model together, patients were subgrouped as receiving graft from “without missing self and without KIR ligand mismatch (R-L match and L-L match)” (n=13), “with missing self and without KIR ligand mismatch (R-L mismatch and L-L match)” (n=47), and “with missing self and with KIR ligand mismatch (R-L mismatch and L-L mismatch)” (n=18), respectively. Cox regression model showed the 10-yearDFSwas best predicted by the combination of missing self model and Ligand-ligand modelbetween recipients and donors pairs (HR 2.205(1.113-4.368), p=0.023, Figure1C). Meanwhile, donor KIR 2DS5 positive associated with higher DFS post-transplantation (84.2±8.4% vs. 56.8±7.7%, p=0.045) in CML patients. However, donor KIR haplotype B have no effect on DFS and overall survival after allogeneic hematopoietic stem cell transplantation for multiple myeloma Conclusions These data indicate thatpoor prognosis after transplantation is associated with the missing self and KIR ligand mismatch in recipients and T cell alloreaction may play apredominant role in this model.Based on recipients and donor HLA-C and HLA-Bw4 gene content, it could befeasible to identify HLA-mismatched donors who will predict the better prognosis in CML patients post T cell-replete transplant. Disclosures: No relevant conflicts of interest to declare.

Introduction Whether allogeneic hematopoietic stem cell transplantation (allo-HSCT) or imatinib should be first-line therapy for childhood chronic myelogenous leukemia in the chronic phrase (CML-CP) is controversial. This study compared imatinib monotherapy and allo-HSCT for the management of CML-CP in pediatric patients. Methods This was a retrospective study of children (aged Results 62 patients (40 males, 22 females) were enrolled: 41 received imatinib, and 21 received allo-HSCT. Median follow-up in the imatinib and allo-HSCT groups was 29 and 56 months, respectively. Imatinib was well tolerated. In the imatinib group, the cumulative complete cytogenetic response (CCyR) and major molecular response (MMR) at 24 months were 96.6% (95%CI, 93.3–99.9%) and 85.6% (95%CI, 78.5–92.7%), respectively; patients achieved CCyR and MMR at a median of 3 and 6 months, respectively. In the allo-HSCT group, allografts were from an HLA-matched sibling (n=3), an HLA mismatched/haploidentical familial donor (n=15) or an unrelated donor (n=3). Twelve patients (57.1%) developed acute graft-versus-host disease (grades 2–6 in 7 patients), and 5 deaths were reported. 5-year OS in the imatinib and allo-HSCT groups was 97.1±2.9% and 73.7±10.3% (P=0.032), respectively, while 5-year EFS was 92.5±4.2% and 63.8±11.1% (P=0.041), respectively. Conclusion Treatment with imatinib yielded satisfactory cytogenetic and molecular responses, and superior 5-year OS and EFS to allo-HSCT. Disclosures: No relevant conflicts of interest to declare.

Abstract 3853 Background With the incorporation of more aggressive therapies such as hematopoietic stem cell transplantation (HSCT), more myelodysplastic syndromes (MDS) patients fall into a status of minimal residual disease (MRD). The sensitive molecular markers are required to monitor MRD and predict relapse. The Wilms' tumor gene (WT1) is now a widely accepted molecular marker of MDS. However, WT1 itself could not fully meet the demands because a subset of MDS patients does not overexpress WT1, and the increase of WT1 expression compared with the normal control of MDS patients was mainly within 2-log. We wondered if the preferentially expressed antigen of melanoma (PRAME) gene could supplement WT1. Methods The PRAME and WT1 transcript levels were simultaneously measured in 312 bone marrow samples collected from newly diagnosed MDS patients and 27 samples from non-malignant cytopenia patients. Bone marrow samples from 14 MDS patients after their disease progression were also detected. To evaluate the value of combined detection of WT1 and PRAME transcripts, one hundred and eleven BM samples collected from 17 MDS patients during their treatment were tested them simultaneously (chemotherapy alone: 1 patient; HSCT:16 patients). Bone marrow samples from six MDS patients and five normal controls were sorted into the blasts (CD34+), nucleated erythrocytes (CD71+), immature myeloid cells (CD33+CD34-), and lymphocyte (CD45+high, low SSC) fractions by flow cytometry and measured the PRAME and WT1 transcript levels, respectively. We had previously established that the upper limits of the PRAME and WT1 transcript levels tested in normal bone marrow samples were 0.28% and 0.50%, respectively. Results None of the 27 non-malignant cytopenia patients overexpressed PRAME (median 0.085%, range 0.01%-0.28%) and WT1 (median 0.095%, range 0.0089%-0.36%). Both WT1 and PRAME were commonly overexpressed in MDS. Both the overexpression frequency and the >1-log increase expression frequency of PRAME were similar to those of WT1 (74.4 % vs 77.6%; 51.6% vs 49.0%; p>0.05), and 88.1% of the patients overexpressed at least one marker. Moreover, the frequencies of PRAME expression with higher degrees of increase were significantly higher compared with those of WT1 expression (>2-log increase: 30.8% vs 3.8%; >3-log increase: 9.0% vs 0%; all p Conclusion The combined detection of WT1 and PRAME transcripts in newly diagnosed MDS patients could find more suitable and sensitive molecular marker for them compared to detecting WT1 alone. The PRAME and WT1 transcripts constitute a good molecular marker combination for monitoring minimal residual disease in MDS. Disclosures: No relevant conflicts of interest to declare.

Abstract 4463 Background: Thrombocytopenia is a critical complication following allogeneic hematopoietic stem cell transplantation (allo-HSCT), but its pathogenesis has remained obscure. Thrombopoietin (TPO) has been identified as a key cytokine for both megakaryogenesis and thrombopoiesis; however, the kinetics of TPO production after allo-HSCT has not been reported. This study characterized the kinetics of TPO and its correlation with the megakaryocyte ploidy distribution pattern within 60 days of allo-HSCT. Methods and Results: A total of 46 consecutive patients who underwent allo-HSCT from October 2008 to December 2008 were included in the study. The TPO levels and the ploidy distribution pattern of MKs were measured using ELISA and flow cytometric analysis, respectively. The results indicate that the TPO levels and the platelet counts followed opposite trends after allo-HSCT. Multivariate analysis indicate that endogenous TPO levels before allo-HSCT, and the number of transplanted CD34+ cells were significant predisposing factors for rapid platelet engraftment (P=0.010 and 0.007, respectively). Furthermore, we found a reduction of ploidy and an increase in immature MKs in patients with higher endogenous TPO levels (> 250 pg/ml) on day 60 after allo-HSCT. Moreover, lower TPO levels (≤250 pg/ml) on day 60 after allo-HSCT were associated with significantly improved 2-year OS (P=0.032) and reduced TRM (P=0.026). Conclusion: Our results suggest that increased endogenous TPO levels may not be sufficient after allo-HSCT, and that the decreased ability of TPO may account for the appearance of antibodies. The use of exogenous rhTPO may promote platelet recovery after allo-HSCT. However, these possibilities need to be examined further. Disclosures: No relevant conflicts of interest to declare.

Abstract 139 Background Although patients with acute myeloid leukemia (AML) and the t(8;21) translocation generally have a favorable prognosis, relapse occurs in about 40% of cases and long-term (>5years) survival less than 50%. Patients with a KIT-mutation had an even higher relapse rate up to 70% and dismal survial. Once relapse, the outcome is extremely poor, even receiving allogeneic hematopoietic stem-cell transplantation (allo-HSCT).Therefore, rapidly identifying high-risk relapse patients and preemptively treating them with more aggressive therapy, such as HSCT, may decrease the chance of relapse and improve patient survival. We sought to improve outcome in patients with t(8;21) acute myeloid leukemia(AML) in first complete remission (CR) by applying risk-directed therapy that was based on measurements of minimal residual disease (MRD) by quantitative PCR during treatment. Methods From June 1,2005, to Dec 31, 2011, 137 patients with t(8;21) AML were enrolled at three centres. MRD was detected using quantitative PCR to detect the RUNX1/RUNX1T1 transcript. High-risk was defined by not achieving major molecular remission (MMR,> 3 log reduction of RUNX1/RUNX1T1 transcript from baseline) after second consolidation therapy or loss of MMR within 6 months since achieving MMR. Low-risk was defined by achieving MMR after second consolidation therapy and maintenance of MMR within 6 months thereafter. High-risk patients were recommended to receive allogeneic hematopoietic stem-cell transplantation (allo-HSCT) and low-risk patients to high-dose cytarabine-based consolidation chemotherapy. 116 patients who achieved CR and completed second consolidation were assigned to risk-directed therapy. Finally, sixty-nine patients actually received risk-directed therapy and 47 patients received a non risk-directed treatment for patients¡ bias. Findings With a median follow-time of 36 months in patients alive, risk-directed therapy and non risk-directed therapy achieved 5 year cumulative incidence of relapse(CIR) of 15.0%±4.7% and 57.5%±8.0%(p Interpretation Risk-stratification treatment directed by MRD could improve the outcome of AML with t(8;21) in first complete remission. Allo-HSCT benefits high-risk as well as KIT-mutated but impairs low-risk patients¡ survival. Disclosures: No relevant conflicts of interest to declare.

Abstract 3338 Background: Refractory immune thrombocytopenia (RITP) is a severe bleeding disorder with a high mortality rate of 10% to 30%, which is resulted from the toxicities associated with therapies, as well as from life-threatening bleedings. Up to now, treatments for RITP patients are still limited and no consensus has been reached about the standard treatment protocol, therefore, it remains a great problem and challenge for hematologists to think out ways to treat RITP, that is to say, new therapies should be explored to maintain a relatively stable and safe platelet counts with minimum toxicities, so as to improve patients' quality of life and reduce mortalities related to severe bleedings and therapies. ITP is an autoimmune disorder ascribed not only to increased PLT destruction, but also to reduced PLT production, which appears to be related to impaired megakaryocytes (MKs) maturation. ATRA belongs to a class of retinoids, which exerts immunomodulatory and differentiation inducing capacities, and has been included in clinical trails about autoimmune diseases and has been successfully applied in clinic to cure APL by inducing the differentiation of cancer cells. Design and Methods: In this study, we retrospectively reviewed the medical charts of 35 RITP patients who took ATRA as part of the combination therapy from February 2008 to August 2012. We made phone calls for some other detailed medically relevant information not recorded, including previous ITP history, bleeding episodes and etc. All the patients fulfilled the primary ITP criteria as described. They had a median ITP duration of 29 months (range, 6–129 months), with a diagnosed RITP duration of 11months (range, 2–79 months). All the patients have received a median of 6 therapies (range, 3–8) prior to taking ATRA, including steroids, IVIG, CSA, azathioprine, danazol and etc. The median lowest PLT number in the course of their disease was 12×109/L (range, 1–27×109/L), and the median PLT count before starting take ATRA was 11×109/L (range, 1–23×109/L). Patients were treated with ATRA (10mg 3times/day), in combination with any one of methylprednisolone, danazol and CSA or nothing not randomly. When patients were severely thrombocytopenia or present with bleeding sings or symptoms, transfusion of PLT or injection of thrombopoietin were applied. Patients were monitored every 1 to 3 days at the first two weeks and every 1to 4 weeks afterwards for PLT counts, and were monitored every 1 month for transaminitis and other side effects. Results: Of the 35 patients, 25 responded to our treatments in a median of 8 weeks (range, 3–16 weeks), with PLT increased to greater than 30*109/L, and remained in remission in a median of 24 months, after which, 10 patients relapsed and 8 patients regained remission with the addition of other drugs. The other 15 patients remained in remission after 24 months during the maintenance therapy process and the following drugs decrement process. 5 patients had a relatively stable and safe PLT count (median 58×109/L, rang 38–225×109/L) after discontinuation of all the medications and the other 10 continued the therapy with a low dose for relapsing after the medicine discontinuation. The median peak PLT count after starting the ATRA therapy was 94×109/L (rang 57–225×109/L), and it is after a median of 3 month (range, 1.5–8 months) before the median PLT count reached to peak level. During the treatment process, no severe adverse events and bleedings happened. Patients refractory to previous conventional first-line therapies and combined therapies responded to the combination of ATRA with any one of methylprednisolone, danazol or CSA, which implies that ATRA has the potential of making RITP less refractory and even curing RITP. Given to the limited samples size and nonrandomization of our study, no prognostic factors were found in our study, including sex, age, ITP duration, the lowest PLT count, previous therapy numbers, previous bleeding episodes, the combined drug and etc. Conclusion: ATRA may have the potential to help RITP patients gain remission and maintain remission combined with one of the conventional first-line therapies, which requires to be verified by more large-sized, prospective, randomized, and controlled clinical trials, and the mechanism of ATRA in treating RITP also needs to be further investigated. Disclosures: No relevant conflicts of interest to declare.