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Despite the continuous improvement of leukemia treatment in the clinic, the overall 5-year disease-free survival of acute myeloid leukemia (AML) is only approximately 30%–60% due to relapse and the refractoriness of AML after traditional chemotherapy. Inhibition of poly(ADP-ribose) polymerase (PARP), a member of the DNA damage repair complex, has a strong antitumor effect in solid tumors. However, the role of PARP in AML remains unclear. We found that high levels of PARP1 and PARP2 were positively related to chemotherapy resistance and poor prognosis in patients with AML. Doxorubicin (DOX)-resistant AML cells highly expressed PAPR1 and PARP2. Knockdown of PARP1 and PARP2, or pharmaceutical inhibition of PARP by the PARP inhibitor (PARPi) BGB-290, significantly enhanced the cytotoxicity of DOX in AML cells due to increased DNA damage. PLGA-loading BGB-290 was properly self-assembled into stable BGB-290@PLGA nanoparticles (NPs), which is uniform particle size and good stability. BGB-290@PLGA is easily uptake by AML cell lines and stays for a long time. Combined with DOX, BGB-290@PLGA can significantly improve the chemosensitivity of AML cell lines. Furthermore, BGB-290 and DOX combination treatment dramatically repressed the onset of leukemia and prolonged the survival of THP-1 xenografted mice. Overall, this study demonstrated that PARPi with traditional chemotherapy could be an efficient therapeutic strategy for AML.

Chemotherapy is the primary treatment option for acute myeloid leukemia (AML), but leukemic stem cells (LSC) can survive chemotherapy for disease recurrence and refractory. Here, we found that AML cells obtained from relapsed patients had increased autophagy levels than de novo AML cells. Furthermore, doxorubicin (DOX) treatment stimulated autophagy in LSC by repressing the mTOR pathway, and pharmaceutical inhibition of autophagy rendered chemoresistant LSC sensitive to DOX treatment in MLL-AF9 induced murine AML. Moreover, we developed a self-assembled leucine polymer, which activated mTOR to inhibit autophagy in AML cells by releasing leucine. The leucine polymer loaded DOX (Leu-DOX) induced much less autophagy but more robust apoptosis in AML cells than the DOX treatment. Notably, the leucine polymer and Leu-DOX were specifically taken up by AML cells and LSC but not by normal hematopoietic cells and hematopoietic stem/progenitor cells in the bone marrow. Consequently, Leu-DOX efficiently reduced LSC and prolonged the survival of AML mice, with more limited myeloablation and tissue damage side effects than DOX treatment. Overall, we proposed that the newly developed Leu-DOX is an effective autophagy inhibitor and an ideal drug to efficiently eliminate LSC, thus serving as a revolutionary strategy to enhance the chemotherapy efficacy in AML.

Objective: The apoptotic and cytotoxic effects of arsenic trioxide (ATO) makes it a potentially suitable agent for the treatment of patients with neuroblastoma with poor prognosis; therefore, we try to evaluate the effectiveness and safety of ATO combined with reinduction/induction chemotherapy in children with recurrent/refractory or newly diagnosed stage 4 neuroblastoma. Methods: Retrospective analysis was performed on seven pediatric patients with recurrent /refractory or newly diagnosed stage 4 neuroblastoma treated with traditional reinduction/induction chemotherapy combined with ATO. Results: A total of 7 patients were treated synchronously with ATO and chemotherapy for up to nine courses; all patients received conventional chemotherapy plus a 0.16 mg/kg/day dose of intravenous ATO during reinduction/induction chemotherapy. Treatment was effective in five patients and ineffective in the other two patients. The overall response rate was 71.43% (5 of 7). The side effects of the ATO combination were minor, whereby only treatment in one patient was terminated at the sixth course due to a prolonged QT interval (0.51 s), which returned to normal after symptomatic treatment. Conclusions: ATO can be safely and effectively combined with chemotherapy drugs as a potential alternative means of treatment for high-risk stage 4 neuroblastoma, and we have observed that ATO can restore the sensitivity of chemotherapy in some patients who were resistant to previous chemotherapy. Further investigations and clinical data are required to confirm these observations.

Thrombocytopenia (TCP) may cause severe and life-threatening bleeding. While this may be prevented by platelet transfusions, transfusions are associated with potential complications, do not always work (platelet refractory) and are not always available. There is an urgent need for a synthetic alternative. We evaluated the ability of fibrinogen-coated nanospheres (FCNs) to prevent TCP-related bleeding. FCNs are made of human albumin polymerized into a 100-nm sphere and coated with fibrinogen. We hypothesized that FCNs would bind to platelets through fibrinogen-GPIIb/IIIa interactions, contributing to hemostasis in the setting of TCP. We used two murine models to test these effects: in the first model, BALB/c mice received 7.25 Gy total-body irradiation (TBI); in the second model, lower dose TBI (7.0 Gy) was combined with an anti-platelet antibody (anti-CD41) to induce severe TCP. Deaths in both models were due to gastrointestinal or intracranial bleeding. Addition of antiplatelet antibody to 7.0 Gy TBI significantly worsened TCP and increased mortality compared to 7.0 Gy TBI alone. FCNs significantly improved survival compared to saline control in both models, suggesting it ameliorated TCP-related bleeding. Additionally, in a saphenous vein bleeding model of antibody-induced TCP, FCNs shortened bleeding times. There were no clinical or histological findings of thrombosis or laboratory findings of disseminated intravascular coagulation after FCN treatment. In support of safety, fluorescence microscopy suggests that FCNs bind to platelets only upon platelet activation with collagen, limiting activity to areas of endothelial damage. To our knowledge, this is the first biosynthetic agent to demonstrate a survival advantage in TCP-related bleeding.

Mesenchymal stem cells (MSCs) have potent regulatory effects on immune and inflammatory responses. Recently the findings of functional TLR expression on MSC implicates these receptors in the function established for MSCs. Here we specially investigated the effects of TLR2, 4 ligation in mice MSC on migration, modulation of allogeneic mixed lymphocytes reaction (allo-MLR) and inducing Treg cells. We demonstrated that ligation of TLR2, but not TLR4, could significantly inhibit migration of MSC, impair MSC-mediated immunosuppression on allo-MLR, and reduce MSC-mediated expansion of CD4+CD25+Foxp3+ regulatory T cells. Compared with TLR4 activated MSCs and non-TLR activated MSC, TLR2 activation induced a relatively lower level of CXCL-10 mRNA and protein expressions which has been elucidated to act in concert with other soluble factor in MSC-mediated immunomodulation. These data indicate that TLR2 and TLR4 ligation had different effects on immunomodulatory capability of murine BMSCs, which should be considered in their use for treating inflammatory diseases.

The aim of this study was to prospectively investigate the efficacy and safety of fully matched allogeneic hematopoietic stem cell transplants in children with severe aplastic anemia in China. A total of twenty patients with severe aplastic anemia were enrolled in our study. Thirteen cases underwent transplantation with fully human leukocyte antigen (HLA)-matched, granulocyte-colony stimulating factor (G-CSF)-primed bone marrow and peripheral blood stem cells (PBSCs) from matching sibling donors. One patient received fully HLA-matched bone marrow from an unrelated donor. Six patients received fully HLA-matched G-CSF-primed PBSCs from unrelated donors. The conditioning regimen included fludarabine, cyclophosphamide, and rabbit anti-thymocyte globulin. Graft-versus-host disease prophylaxis was conducted with cyclosporin A and short-course methotrexate. The median follow-up duration was 3.08 years (range, 0.83-8.41years). The median time of neutrophil recovery (>0.5 x 10(9)/L) was 14 days (range, 10-20 days), and the median time of platelet recovery (>20 x 10(9)/L) was 19 days (range, 14-31 days). The survival rate at the cutoff point of follow-up was 95.0% (19/20). Initial engraftment rate was 95% (19/20). Late graft failure (graft failures occurring 1 year or longer after transplantation) was observed in one patient. Only one patient developed Grade I acute graft-versus-host disease. Two cases suffered from Epstein- Barr virus (EBV)-associated post-transplant lymphoproliferative disorder and remitted after treatment with rituximab. One patient was diagnosed with hyperthyroidism 2.5 years after transplantation. Our study indicated that allogeneic hematopoietic stem cell transplantation is an effective and safe treatment for children with severe aplastic anemia in China.

To evaluate factors affecting outcome of sibling umbilical cord blood transplantation in Chinese children with thalassemia. The authors conducted a retrospective review of all patients undergoing such transplants in a single institution. Nine children with thalassemia major were diagnosed at a median age of 12 months. They received irregular blood transfusions and suboptimal iron chelation therapy before transplant. Sibling cord blood transplant was performed at a median of 5.5 years (range 3.5-10 years). Six donors were HLA-identical; three were one- to three-antigen mismatched. The mean number of nucleated cells infused was 6.6 x 10(7)/kg (range 3.4-12.7); the mean number of CD34+ cells infused was 3.8 x 10(5)kg (range 0.6-11.7). Seven patients had engraftment of donor cells. The median number of days to achieve a neutrophil count of > 0.5 x 10(9)/L was 19 days (range 10-25); the median number of days to achieve a platelet count of > 20 x 10(9)/L was 33 days (range 19-63). Of the six patients who received HLA-identical transplants, one developed grade 2 and two developed grade 1 acute graft-versus-host disease. Two of the three patients receiving mismatched cord blood did not achieve engraftment, and the other one engrafted but developed grade 4 acute graft-versus-host disease. Two patients subsequently developed secondary graft rejection and had autologous marrow regeneration before day 60 posttransplantation. With a median follow-up of 49 months (range 38-64), eight patients survived but only four were transfusion-independent. Umbilical cord blood transplant appears to have a higher chance of nonengraftment and secondary rejection. A more intensive immunosuppressive conditioning regimen may be required.

Six transfusion-dependent &#103 -thalassemia major patients were treated with allogeneic peripheral blood stem cell (PBSC) transplant. The donors were HLA identical siblings except one donor who was a father with one-antigen mismatch of HLA-B loci. The donors were mobilized with G-CSF and PBSC was infused without manipulation. Engraftment was documented in all patients. Acute graft versus host disease (GvHD) was present in 4 patients but could be controlled with steroid or/and ATG. One patient died of hepatic veno-occlusive disease (HVOD) and survivors were all transfusion independent (ex-thalassemia). Chronic GvHD occurred in one patient. Allogeneic PBSC transplantation could achieve disease-free survival in &#103 -thalassemia major patients.

Abstract 4058 Poster Board III-993 Background Despite the availability of effective chelators, many patients (pts) with β-thalassemia major (TM) present with high iron burden and serum ferritin (SF) >2500 ng/mL, demonstrated to be associated with significant negative outcomes including cardiac disease and organ failure. In the large, prospective EPIC trial including 854 TM pts who received prior chelation therapy, median baseline SF was 3139 ng/mL despite 10.8 yrs of therapy; hence the therapeutic goal was to reduce iron burden. Previous studies have shown that in TM pts with high transfusional iron, ≥30 mg/kg/day deferasirox (Exjade®) doses significantly reduce SF, while 20 mg/kg/day doses maintained SF levels. The objective of this analysis was to assess whether a mean actual deferasirox dose ≥30 mg/kg/day is effective in reducing SF in iron-overloaded pts with TM irrespective of prior chelation therapies. Methods Pts with TM (≥2 yrs) and transfusional iron overload as defined by SF levels ≥1000 ng/mL or 20 transfusions or 100 mL/kg of blood) and R2 MRI-confirmed liver iron concentration >2 mg Fe/g dry weight were enrolled. Initial deferasirox dosing (10–30 mg/kg/day) was dependent on transfusion requirements and adjusted according to the protocol by 5–10 mg/kg/day (range 0–40 mg/kg/day) every 3 months based on SF trends and safety markers. Pts previously chelated with monotherapy deferoxamine (Desferal®; DFO) or deferiprone (Ferriprox®; DFP) or a combination of both and who received a mean actual deferasirox dose ≥30 mg/kg/day over 1 yr were included. The primary efficacy endpoint was the change in SF at 1 yr from baseline (BL). Results Overall, 129 TM pts (15%) who were previously chelated with DFO and/or DFP were treated with a mean actual deferasirox dose of ≥30 mg/kg/day during the 1 yr EPIC trial; 83 pts received prior DFO or DFP monotherapy and 46 received a combination of both. Mean age was 19.5±8.2 vs 23.0±7.2 yrs in prior monotherapy and prior combination therapy pts, respectively. A mean of 167 mL/kg vs 191 mL/kg was transfused in the yr prior to study entry and the mean duration of prior chelation therapy was 11.7±7.7 yrs vs 14.5±7.9 yrs, respectively. During the study, mean transfusional iron intake was similar in both groups (0.36±0.2 and 0.34±0.1 mg/kg/day, respectively). In prior monotherapy pts (mean dose 33.9±2.2 mg/kg/day), median SF decreased from 4885 ng/mL at BL to 4282 ng/mL after 1 yr (Figure) resulting in a decrease from BL of 1024 ng/mL (P Overall, five pts (3.9%) discontinued therapy. Reasons for withdrawal were adverse events (AEs; cardiac failure), abnormal laboratory values (increased transaminases), consent withdrawal, lost to follow-up and protocol violation (all n=1). The most common investigator-assessed drug-related AEs were rash (n=14, 10.9%) and diarrhea (n=12, 9.3%). One pt (0.8%) had serum creatinine >33% above BL and the upper limit of normal (ULN) on two consecutive visits and one pt (0.8%) had increased alanine aminotransferase >10xULN on two consecutive visits; levels were already elevated. Conclusions This heavily transfused subgroup of TM pts, who had received prior chelation therapy with DFO and/or DFP for an average >10 yrs, continued to have high SF levels >4500 ng/mL. Monotherapy with ≥30 mg/kg/day deferasirox for 1 yr led to significant and clinically relevant reductions in SF in these pts irrespective of previous chelation therapies and was well tolerated. Longer-term studies are required to assess whether continued deferasirox could reduce SF Disclosures: Taher: Novartis: Honoraria, Research Funding. Chan:Novartis: Honoraria, Research Funding. Li:Novartis: Consultancy, Speakers Bureau. Lin:Taiwan Pediatric Onclogy Group (TPOG): Consultancy; Novartis: Honoraria, Speakers Bureau. Porter:Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Vifor International: Membership on an entity's Board of Directors or advisory committees. Sutcharitcharan:Novartis: Honoraria, Research Funding; Novo Nordisk: Honoraria. Habr:Novartis Pharmaceuticals: Employment. Domokos:Novartis Pharma AG: Employment. Roubert:Novartis Pharma AG: Employment. Cappellini:Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Genzyme: Membership on an entity's Board of Directors or advisory committees.

Objective To evaluate the clinical efficacy and complications of related (RD) umbilical cord blood transplantation (UCBT) or unrelated (UD) UCBT for children with leukemia or whom with b-thalassemia (TM). Methods Ten patients with TM received RD-UCBT (group 1), while another 10 patients with TM had UD-UCBT (group 2).13 patients with leukemia (4 high risk ALL and 9 AML) were transplanted from UD-UCB (group3). Of 7 were HLA-identical, a patient was a loci-mismatched and two of them were half matched in group 1. Meanwhile, in the group2, three of ten patients were HLA matched, six was a loci-mismatched and one received double unites of UD-UCB that was from HLA matched to a loci-mismatched. Furthermore, ten of 13 patients were one loci-mismatched in group 3. Two were two loci-mismatched and one received double unites of UD-UCB from HLA matched to a loci-mismatched in the group. The conditioning regimen was consisted of busulfan (Bu) 14–20 mg /kg, cyclophosphages(Cy) 120–200 mg /kg and horse antithymocyte globulin (ATG)90 mg /kg or rabbit ATG 25 mg /kg for all TM patients. Of them, 6 also received melphalan (Melph) 90 mg /m2. Four patients had fludarabine (Flu) 150 mg /m2. Three combined Flu with thiotepa (TT) 6 mg /kg. Five used Flu, TT and TBI together. In the group of patients with leukemia (group 3), the regimen was divided into two branches: (1) Non-TBI regimen: the regimen mainly focused on 10 patients with leukemia in the CR phase except a patient was too young although him in the NR phase, which was consisted of Bu, Cy, ATG and Flu. A patient added high dose Ara-C. One had IDA, and 3 Melph. (2). Accompanying with TBI regimen. Only had two patients who were in the phase of NR used this regimen. The dose of TBI was 7.5 Gy and 6.5 Gy respectively. The patients received the nucleated cells 7.5 (3.4–19.4)’107/kg, CD34 cell 4.5 (0.6–11.7) ’105/kg, CFU-GM 1.1 (0.2–23) ’105/kg in three groups. Result: The engraftment occurred 7 in 10 at the group 1. One patient developed acute GVHD grade III. Two patients rejected 2 months post RD-UCBT. The following up was from 34–69 months in the group and 4 cases remained in the EFS. However, only 3 out of 10 were engraftment in the group 2. The others all were antologous reconstitution in the failure patients. One developed acute GVHD grade II in the group 2. The following up was from 3 months to 43 months in the group. Two cases kept EFS but one died of IP at the 6 months post transplantation. 11 out of 13 patients engrafted in the group 3. Nine patients were EFS post transplantation and the time of following up was from 4 to 37 months in the group. One developed severe acute GVHD and 3 had extensive chronic GVHD.

Summary IGF-1 administered after exposure significantly improves survival after lethal total body irradiation through accelerating hematopoietic recovery. IGF-1 protects hematopoietic stem cells and progenitor cells from radiation-induced apoptosis and cell death. IGF-1 also enhances proliferation and differentiation of the surviving hematopoietic progenitor cells. Purpose: To investigate whether and how insulin-like growth factor 1 (IGF-1) mitigates hematopoietic toxicity after total body irradiation. Methods and Materials: BALB/c mice were irradiated with a lethal dose of radiation (7.5 Gy) and treated with IGF-1 at a dose of 100 mg/dose intravenously once a day for 5 consecutive days starting within 1 hour after exposure. Survival and hematopoietic recovery were monitored. The mechanisms by which IGF-1 promotes hematopoietic recovery were also studied by use of an in vitro culture system. Results: IGF-1 protected 8 of 20 mice (40%) from lethal irradiation, whereas only 2 of 20 mice (10%) in the saline control group survived for more than 100 days after irradiation. A single dose of IGF-1 (500 mg) was as effective as daily dosing for 5 days. Positive effects were noted even when the initiation of treatment was delayed as long as 6 hours after irradiation. In comparison with the saline control group, treatment with IGF-1 significantly accelerated the recovery of both platelets and red blood cells in peripheral blood, total cell numbers, hematopoietic stem cells, and progenitor cells in the bone marrow when measured at day 14 after irradiation. IGF-1 protected both hematopoietic stem cells and progenitor cells from radiation-induced apoptosis and cell death. In addition, IGF-1 was able to facilitate the proliferation and differentiation of nonirradiated and irradiated hematopoietic progenitor cells. Conclusions: IGF-1 mitigates radiation-induced hematopoietic toxicity through protecting hematopoietic stem cells and progenitor cells from apoptosis and enhancing proliferation and differentiation of the surviving hematopoietic progenitor cells. 2013 Elsevier Inc.