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Background Optimization of pre-transplant risk assessment is a crucial issue to improve the allo-HSCT decision making process. Actually 3 major algorithms are in use in clinical practice: the EBMT risk score, the Hematopoietic Cell Transplantation Comorbidity Index (HCT-CI) score and - more recently introduced - the refined Disease Risk Index (DRI). DRI was defined to calibrate HSCT outcome across studies and centers. It was developed as a tool to assign patients into risk groups based on disease type and status at the time of transplantation. The aim of the DRI is to provide a robust tool that can be used for prognostication, for the analysis and interpretation of retrospective data, whether conducted in single-center, multicenter, or registry settings, or within the context of the federally mandated center outcome reporting. The DRI can also be used for the stratification of patients entering prospective HCT clinical trials. DRI is not a fixed tool but instead it was conceived to be refined by the transplant community as new information becomes available. Here we are presenting the results of a retrospective study designed to evaluate the 3 aforementioned score in stratification and prognostication of transplant outcome after a haploidentical HSCT (haplo-HSCT). Patients and Methods We included 220 adult patients (pts - 138 male, 82 female) who underwent a haplo-HSCT for hematologic malignancies, between 2006 and 2014 and were reported to our Institutional database. Risk assessment score and outcome analysis included all consecutive pts receiving an haplo-HSCT as 1st allogeneic transplantation. Pts receiving haplo-HSCT as 2nd or 3rd HSCT were excluded from the present analysis. Median age was 49 years (range, 15-77). The cohort included a broad representation of diseases (138/220 acute leukemia, 30 Hodgkin lymphoma); 62 pts were in complete remission at transplant, 158 were presenting active disease. Conditioning regimens mostly rely upon the combination of treosulfan plus fludarabine (201/220) and total body irradiation (range 200 - 400 cGy) was utilized in 52 patients. GVHD prophylaxis consisted mostly of an mTor inhibitor (rapamycin) combined with mycophenolate mofetil. The majority of patients received peripheral blood stem cells from a family haploidentical donor as stem cell source, while only 4 patients received bone marrow transplant. A written consent was given by pts allowing the use of medical records for research in accordance with the Declaration of Helsinki. Results The median follow-up for survivors was 37 months (r 6-107). The overall survival (OS) at 2-y was 35% and the transplant related mortality at 100-days 23%. The 2y OS according to EBMT / HCT-CI / DRI risk score are reported in table 1.a and figure 1. The evaluation of the HCT-CI impact after DRI stratification was able to show a significant difference in outcome showing better survival for pts with low DRI score and low HCT-CI score as expected (table 1.b). Discussion Refined DRI score and HCT-CI score predict survival after haplo-HSCT. The integrated application of refined DRI and HCT-CI may improve the definition of transplant eligibility for pts candidate to allogeneic HSCT form alternative donors including family haploidentical source. Table 1a. EBMT score 0-3 % pts 4-5 %pts > 5 %pts p 51% 17 34% 51 27% 32 0.07 HCT-CI score 0-2 3-4 >/= 5 48% 59 36% 31 0% 10 0.0001 DRI score Low-Intermediate High Very-High 61% 32 27% 51 5% 17 0.0001 Table 1b. HCT-CI 0-4 HCT-CI >/=5 p DRILow-Intermediate 64% 0% 0.0001 DRIHigh-Very High 29% 0% Figure 1. Figure 1. Disclosures No relevant conflicts of interest to declare.

Over the past decades outcomes of clinical hematopoietic stem cell transplants have established a clear relationship between the sources of hematopoietic stem cells (HSCs) infused and their differential homing and engraftment properties. For a long time, bone marrow (BM) harvest has been the preferred source of hematopoietic stem and progenitor cells (HSPCs) for hematopoietic reconstitution following myeloablative conditioning regimen. At present, mobilized peripheral blood (PB) is commonly used for hematopoietic cells transplantation in both adults and children, particularly in the autologous setting, and it has progressively replaced BM as the source of HSCs. So far, the intrinsic molecular features of human primitive HSCs from different sources have not been investigated in comparative studies to unravel their variable reconstitution potential. Diverse strategies are currently used to disengage HSCs from the niche, promoting egress from BM to PB. Traditionally the growth factor granulocyte-colony stimulating factor (G-CSF) represents the gold standard agent to mobilize HSPCs for transplantation. Nevertheless, many other compounds have been tested to this regard. One of the most successful mobilizing agents is Plerixafor (AMD3100, Mozobil™), a bicyclam molecule that selectively and reversibly antagonizes the binding of stromal cell derived factor-1 (SDF-1), located on the surface of BM stromal cells and osteoclasts, to chemokine CXC-receptor-4 (CXCR4), located on the surface of HSPCs, with the subsequent mobilization in the PB. This drug, which was shown in preclinical combination studies with G-CSF to enhance mobilization compared to G-CSF alone, is currently approved by FDA and EMA "in combination with G-CSF to enhance the mobilization of HSCs into the peripheral blood for collection and autologous transplantation of patients affected by lymphoma or multiple myeloma whose cells mobilize poorly" We investigated functional and molecular hallmarks of human HSCs from different sources, i.e. BM and PB following mobilization by G-CSF and/or Plerixafor. We show that Plerixafor alone mobilizes preferentially long-term hematopoietic stem cells (LT-HSCs), defined as CD34+ CD38/low CD90+ CD45RA- CD49f+ cells and primitive populations of HSCs. These cells are able to provide stable long-term hematopoietic engraftment in NOD/SCID/IL2rγnull (NSG) mice, resulting in enriched scid-repopulating cell frequency, in comparison to other sources. The quiescence status of these cells correlates with the enriched scid-repopulating cell frequency. Noteworthy, the combined use of G-CSF and Plerixafor mobilizes a CD34+ population enriched in immature cells and with a lower engraftment capacity respect to cells mobilized by Plerixafor alone. Since the signaling provided by the interaction of SDF-1 with CXCR4, plays an essential role in maintaining HSC quiescence and regulating homing, we analyzed the CXCR4 expression. Interestingly, this analysis reveals that the proportion of CXCR4+ primitive cells was lower when using G-CSF combined to Plerixafor in respect to Plerixafor alone. These data indicate that the combination of the two mobilizing agents induce a higher amount of circulating CD34+ cells but containing a lower proportion of cells capable of homing to BM in NSG mice. . As a result, at a defined dose of transplanted CD34+ cells, less SRCs are observed when G-CSF is added to Plerixafor. Indeed, it is expected to observe also a rapid rescue of hematopoiesis in myeloablated subjects conferred by high amount of short-term progenitors. Insights into the transcriptional program reveal the molecular machinery underlying stemness features of cells derived from different sources, defining their specific functional properties. Noteworthy, CD34+ cells exposed to Plerixafor but still resident in the BM acquire an intermediate signature between steady-state and circulating cells, suggesting an effect of this agent on HSC function. From preliminary data, genes of Prostaglandin signaling are up-regulated in HSCs mobilized by Plerixafor, suggesting a role of this pathway. These data uncover unique HSCs properties shaped by their origin and illuminate the choice of different transplantation strategies accordingly to the clinical need. Disclosures No relevant conflicts of interest to declare.

A 79-year-old patient with post-polycythaemic myelofibrosis presented with severe hypersplenism. After splenic artery catheterization, cytosine arabinoside was given intrasplenically from November 1999 to March 2000 for 5 d/month at 10 mg/m2 and increased each month by 10 mg/m2. It was then administered by continuous infusion until June 2000, starting at 20 mg/m2/d and tapering by 5 mg/m2 every 2 weeks to a final daily dose of 5 mg/m2/d. The drug was then stopped. The spleen had decreased to one third of the initial volume. Clinical conditions and haematological indices improved substantially. Intrasplenic therapy could be a new therapeutic tool for hypersplenism in chronic idiopathic and post-myeloproliferative myelofibrosis.

beta-Thalassemia is a severe inherited anemia caused by insufficient production of beta-globin chains. Allogeneic hematopoietic stem cell (HSC) transplantation is currently the only cure, and is limited by donor availability and regimen-related toxicity and mortality. Gene therapy is a promising therapeutic tool for all thalassemic patients lacking a compatible donor and potentially provides transfusion independence in the absence of transplant-related complications, such as graft rejection and graft-versus-host disease. The issue of HSC procurement is critical in this setting because of the specific features of thalassemic syndromes, which include bone marrow (BM) expansion, ineffective erythropoiesis, and splenomegaly. Little is known about the efficiency of CD34(+) cell yield from steady-state BM harvests from thalassemic patients. We have collected data on safety and cell yield from 20 pediatric patients with beta-thalassemia who underwent autologous BM harvest before allogeneic HSC transplantation, and from 49 age-matched sibling donors who also underwent BM harvest. The procedure was safe, as no significant adverse events occurred. In terms of cell yield, no difference was found between patients and normal donors in the number of CD34(+) cells and total nucleated cells harvested. Most importantly, no difference was found in the proportion of myeloid and erythroid progenitors, suggesting a similar repopulating capacity. On the basis of these results, we conclude that steady-state BM can be used as a safe and efficient source of HSC for gene therapy of b-thalassemia. "beta-Thalassemia is a severe inherited anemia caused by insufficient production of beta-globin chains. Allogeneic hematopoietic stem cell (HSC) transplantation is currently the only cure, and is limited by donor availability and regimen-related toxicity and mortality. Gene therapy is a promising therapeutic tool for all thalassemic patients lacking a compatible donor and potentially provides transfusion independence in the absence of transplant-related complications, such as graft rejection and graft-versus-host disease. The issue of HSC procurement is critical in this setting because of the specific features of thalassemic syndromes, which include bone marrow (BM) expansion, ineffective erythropoiesis, and splenomegaly. Little is known about the efficiency of CD34(+) cell yield from steady-state BM harvests from thalassemic patients. We have collected data on safety and cell yield from 20 pediatric patients with beta-thalassemia who underwent autologous BM harvest before allogeneic HSC transplantation, and from 49 age-matched sibling donors who also underwent BM harvest. The procedure was safe, as no significant adverse events occurred. In terms of cell yield, no difference was found between patients and normal donors in the number of CD34(+) cells and total nucleated cells harvested. Most importantly, no difference was found in the proportion of myeloid and erythroid progenitors, suggesting a similar repopulating capacity. On the basis of these results, we conclude that steady-state BM can be used as a safe and efficient source of HSC for gene therapy of b-thalassemia."

Background: Gene therapy (GT) with hematopoietic stem cells is a promising treatment for inherited immunodeficiencies. Objectives: Limited information is available on the relative contribution of de novo thymopoiesis and peripheral expansion to T-cell reconstitution after GT as well as on the potential effects of gene transfer on hematopoietic stem cells and lymphocyte replicative lifespan. We studied these issues in patients affected by adenosine deaminase severe combined immune deficiency after low-intensity conditioning and reinfusion of retrovirally transduced autologous CD34(+) cells. Methods: Immunophenotype, proliferative status, telomere length, and T-cell receptor excision circles were investigated at early and late time points (up to 9 years) after GT treatment. Control groups consisted of pediatric healthy donors and patients undergoing allogeneic bone marrow transplantation (BMT). Results: We observed no telomere shortening in the bone marrow compartment and in granulocytes, whereas peripheral blood naive T cells from both GT and BMT patients showed a significant reduction in telomere length compared with healthy controls. This was in agreement with the presence of a high fraction of actively cycling naive and memory T cells and lower T-cell receptor excision circles. Conclusion: These data indicate that T-cell homeostatic expansion contributes substantially to immune reconstitution, like BMT, and is not associated with senescence in the stem cell compartment. (J Allergy Clin Immunol 2011;127:1368-75.) BACKGROUND:Gene therapy (GT) with hematopoietic stem cells is a promising treatment for inherited immunodeficiencies.OBJECTIVES:Limited information is available on the relative contribution of de novo thymopoiesis and peripheral expansion to T-cell reconstitution after GT as well as on the potential effects of gene transfer on hematopoietic stem cells and lymphocyte replicative lifespan. We studied these issues in patients affected by adenosine deaminase severe combined immune deficiency after low-intensity conditioning and reinfusion of retrovirally transduced autologous CD34(+) cells.METHODS:Immunophenotype, proliferative status, telomere length, and T-cell receptor excision circles were investigated at early and late time points (up to 9 years) after GT treatment. Control groups consisted of pediatric healthy donors and patients undergoing allogeneic bone marrow transplantation (BMT).RESULTS:We observed no telomere shortening in the bone marrow compartment and in granulocytes, whereas peripheral blood naive T cells from both GT and BMT patients showed a significant reduction in telomere length compared with healthy controls. This was in agreement with the presence of a high fraction of actively cycling naive and memory T cells and lower T-cell receptor excision circles.CONCLUSION:These data indicate that T-cell homeostatic expansion contributes substantially to immune reconstitution, like BMT, and is not associated with senescence in the stem cell compartment.

Recently vancomycin-resistant and sporadically linezolid-resistant Enterococcus species have been described in adults. We report what we believe to be the first case of a child with prolonged bone marrow aplasia following haematopoietic stem cell transplantation developing a fatal sepsis caused by Enterococcus faecium resistant to glycopeptides and linezolid. Recently vancomycin-resistant and sporadically linezolid-resistant Enterococcus species have been described in adults. We report what we believe to be the first case of a child with prolonged bone marrow aplasia following haematopoietic stem cell transplantation developing a fatal sepsis caused by Enterococcus faecium resistant to glycopeptides and linezolid.

Immune-mediated refractoriness to platelet transfusion is a major problem in patients undergoing HSCT. In a cohort of 50 pediatric patients affected by beta thalassemia coming from Middle East countries, we experienced a high incidence of refractoriness because of anti-HLA antibodies during post-HSCT aplasia. In a risk factors analysis, factors predicting a negative transfusion outcome were presence of spleen and the number of anti-HLA antibodies. We adopted a policy to select platelet donors by avoiding HLA antigens against which the patient had specific antibodies. Transfusion of dedicated units resulted in 26% refractoriness compared to 74% to random units (p < 0.0001). When dedicated transfusions were used, the presence of spleen did not influence transfusion outcome. Analyzing transfusion outcome depending on the degree of HLA match and ABO compatibility, 76% successful transfusions were obtained with HLA-matched- ABO compatible followed by 67% in HLA-1mismatch- ABO compatible or HLA-matched- ABO incompatible and by 46% in HLA-1mismatch- ABO incompatible. In conclusion, we provide evidence that the selection of platelet donors according to patient characteristics, anti-HLA antibodies and ABO matching, is successful in reducing platelet refractoriness in heavily alloimmunized thalassemia patients undergoing transplantation. Immune-mediated refractoriness to platelet transfusion is a major problem in patients undergoing HSCT. In a cohort of 50 pediatric patients affected by beta thalassemia coming from Middle East countries, we experienced a high incidence of refractoriness because of anti-HLA antibodies during post-HSCT aplasia. In a risk factors analysis, factors predicting a negative transfusion outcome were presence of spleen and the number of anti-HLA antibodies. We adopted a policy to select platelet donors by avoiding HLA antigens against which the patient had specific antibodies. Transfusion of dedicated units resulted in 26% refractoriness compared to 74% to random units (p < 0.0001). When dedicated transfusions were used, the presence of spleen did not influence transfusion outcome. Analyzing transfusion outcome depending on the degree of HLA match and ABO compatibility, 76% successful transfusions were obtained with HLA-matched- ABO compatible followed by 67% in HLA-1mismatch- ABO compatible or HLA-matched- ABO incompatible and by 46% in HLA-1mismatch- ABO incompatible. In conclusion, we provide evidence that the selection of platelet donors according to patient characteristics, anti-HLA antibodies and ABO matching, is successful in reducing platelet refractoriness in heavily alloimmunized thalassemia patients undergoing transplantation.

beta-Thalassemia is a common monogenic disorder due to mutations in the beta-globin gene and gene therapy, based on autologous transplantation of genetically corrected haematopoietic stem cells (HSCs), holds the promise to treat patients lacking a compatible bone marrow (BM) donor. We recently showed correction of murine beta-thalassemia by gene transfer in HSCs with the GLOBE lentiviral vector (LV), expressing a transcriptionally regulated human beta-globin gene. Here, we report successful correction of thalassemia major in human cells, by studying a large cohort of pediatric patients of diverse ethnic origin, carriers of different mutations and all candidates to BM transplantation. Extensive characterization of BM-derived CD34(+) cells before and following gene transfer shows the achievement of high frequency of transduction, restoration of haemoglobin A synthesis, rescue from apoptosis and correction of ineffective erythropoiesis. The procedure does not significantly affect the differentiating potential and the relative proportion of haematopoietic progenitors. Analysis of vector integrations shows preferential targeting of transcriptionally active regions, without bias for cancer-related genes. Overall, these results provide a solid rationale for a future clinical translation. Beta-thalassemia is a common monogenic disorder due to mutations in the beta-globin gene and gene therapy, based on autologous transplantation of genetically corrected haematopoietic stem cells (HSCs), holds the promise to treat patients lacking a compatible bone marrow (BM) donor. We recently showed correction of murine beta-thalassemia by gene transfer in HSCs with the GLOBE lentiviral vector (LV), expressing a transcriptionally regulated human beta-globin gene. Here, we report successful correction of thalassemia major in human cells, by studying a large cohort of pediatric patients of diverse ethnic origin, carriers of different mutations and all candidates to BM transplantation. Extensive characterization of BM-derived CD34(+) cells before and following gene transfer shows the achievement of high frequency of transduction, restoration of haemoglobin A synthesis, rescue from apoptosis and correction of ineffective erythropoiesis. The procedure does not significantly affect the differentiating potential and the relative proportion of haematopoietic progenitors. Analysis of vector integrations shows preferential targeting of transcriptionally active regions, without bias for cancer-related genes. Overall, these results provide a solid rationale for a future clinical translation.

Background: Neurotoxicity is a recognized complication of cyclosporine A (CSA) treatment. The incidence of severe CSA-related neurological complications following hematopoietic stem cell transplantation (HSCT) is 4-11%. Methods: We describe 6 cases of CSA related neurotoxicity out of 67 matched related HSCT performed in paediatric Middle East patients affected by haemoglobinopaties (5 beta thalassemia major, 1 sickle cell disease-SCD). Conditioning regimen consisted of iv busulphan, cyclophosphamide and graft-versus-host-disease (GvHD) prophylaxis with CSA, methylprednisolone, methotrexate and ATG. Results: All 6 patients presented prodromes such as arterial hypertension, headache, visual disturbances and vomiting, one to two days before overt CSA neurotoxicity. CSA neurotoxicity consisted of generalized seizures, signs of endocranial hypertension and visual disturbances at a median day of onset of 11 days after HSCT (range +1 to +40). Brain magnetic resonance imaging (MRI) performed in all subjects showed reversible leukoencephalopathy predominantly in the posterior regions of the brain (PRES) in 5/6 patients. EEG performed in 5/6 patients was always abnormal. Neurotoxicity was not explainable by high CSA blood levels, as all patients had CSA in the therapeutic range with a median of 178 ng/ml (range 69-250). CSA was promptly stopped and switched to tacrolimus with disappearance of clinical and radiological findings. All patients are symptoms-free at a median follow up of 882 days (range 60-1065). Conclusions: Our experience suggests that paediatric patients with haemoglobinopaties have a high incidence of CSA related neurological events with no correlation between serum CSA levels and neurotoxicity. Prognosis is good following CSA removal. Specific prodromes such as arterial hypertension, headache or visual disturbances occurring in the early post-transplant period should be carefully evaluated with electrophysiological and MRI-based imaging in order to intervene promptly and avoid irreversible sequels. Background: Neurotoxicity is a recognized complication of cyclosporine A (CSA) treatment. The incidence of severe CSA-related neurological complications following hematopoietic stem cell transplantation (HSCT) is 4-11%. Methods: We describe 6 cases of CSA related neurotoxicity out of 67 matched related HSCT performed in paediatric Middle East patients affected by haemoglobinopaties (5 beta thalassemia major, 1 sickle cell disease-SCD). Conditioning regimen consisted of iv busulphan, cyclophosphamide and graft-versus-host-disease (GvHD) prophylaxis with CSA, methylprednisolone, methotrexate and ATG. Results: All 6 patients presented prodromes such as arterial hypertension, headache, visual disturbances and vomiting, one to two days before overt CSA neurotoxicity. CSA neurotoxicity consisted of generalized seizures, signs of endocranial hypertension and visual disturbances at a median day of onset of 11 days after HSCT (range +1 to +40). Brain magnetic resonance imaging (MRI) performed in all subjects showed reversible leukoencephalopathy predominantly in the posterior regions of the brain (PRES) in 5/6 patients. EEG performed in 5/6 patients was always abnormal. Neurotoxicity was not explainable by high CSA blood levels, as all patients had CSA in the therapeutic range with a median of 178 ng/ml (range 69-250). CSA was promptly stopped and switched to tacrolimus with disappearance of clinical and radiological findings. All patients are symptoms-free at a median follow up of 882 days (range 60-1065). Conclusions: Our experience suggests that paediatric patients with haemoglobinopaties have a high incidence of CSA related neurological events with no correlation between serum CSA levels and neurotoxicity. Prognosis is good following CSA removal. Specific prodromes such as arterial hypertension, headache or visual disturbances occurring in the early post-transplant period should be carefully evaluated with electrophysiological and MRI-based imaging in order to intervene promptly and avoid irreversible sequels.

beta-thalassemia is a major health problem worldwide, and stem cell transplantation (SCT) is the only curative option. Oral Busulfan (Bu) based conditioning is widely used in this setting. Due to the variability of Bu systemic exposure, intravenous (i.v.) Bu has been proposed as a standard of care, with no need for drug monitoring and dose adjustment. Patients with beta-thalassemia from countries with limited resources might be at higher risk of erratic Bu metabolism because of liver dysfunction, severe iron overload, and specific ethnic/genetic features. We studied Bu pharmacokinetics in 53 children with advanced beta-thalassemia from Middle Eastern countries who underwent a total of 57 matched related donor SCTs. Forty-two percent of the children required dose adjustment because they did not achieve the therapeutic window after the first dose. With a Bu dose-adjustment policy, regimen-related toxicity was limited. At a median follow-up of 564 days, the probabilities of 2-year survival, current thalassemia-free survival, rejection, and treatment-related mortality were 96%, 88%, 21%, and 4%, respectively. Conditioning with i.v. Bu and dose adjustment is feasible and well tolerated, although recurrence of thalassemia remains an unsolved problem in children with advanced disease. beta-thalassemia is a major health problem worldwide, and stem cell transplantation (SCT) is the only curative option. Oral Busulfan (Bu) based conditioning is widely used in this setting. Due to the variability of Bu systemic exposure, intravenous (i.v.) Bu has been proposed as a standard of care, with no need for drug monitoring and dose adjustment. Patients with beta-thalassemia from countries with limited resources might be at higher risk of erratic Bu metabolism because of liver dysfunction, severe iron overload, and specific ethnic/genetic features. We studied Bu pharmacokinetics in 53 children with advanced beta-thalassemia from Middle Eastern countries who underwent a total of 57 matched related donor SCTs. Forty-two percent of the children required dose adjustment because they did not achieve the therapeutic window after the first dose. With a Bu dose-adjustment policy, regimen-related toxicity was limited. At a median follow-up of 564 days, the probabilities of 2-year survival, current thalassemia-free survival, rejection, and treatment-related mortality were 96%, 88%, 21%, and 4%, respectively. Conditioning with i.v. Bu and dose adjustment is feasible and well tolerated, although recurrence of thalassemia remains an unsolved problem in children with advanced disease. Abstract beta-thalassemia is a major health problem worldwide, and stem cell transplantation (SCT) is the only curative option. Oral Busulfan (Bu) based conditioning is widely used in this setting. Due to the variability of Bu systemic exposure, intravenous (i.v.) Bu has been proposed as a standard of care, with no need for drug monitoring and dose adjustment. Patients with beta-thalassemia from countries with limited resources might be at higher risk of erratic Bu metabolism because of liver dysfunction, severe iron overload, and specific ethnic/genetic features. We studied Bu pharmacokinetics in 53 children with advanced beta-thalassemia from Middle Eastern countries who underwent a total of 57 matched related donor SCTs. Forty-two percent of the children required dose adjustment because they did not achieve the therapeutic window after the first dose. With a Bu dose-adjustment policy, regimen-related toxicity was limited. At a median follow-up of 564 days, the probabilities of 2-year survival, current thalassemia-free survival, rejection, and treatment-related mortality were 96%, 88%, 21%, and 4%, respectively. Conditioning with i.v. Bu and dose adjustment is feasible and well tolerated, although recurrence of thalassemia remains an unsolved problem in children with advanced disease.

Background Thalassemia major can be cured with allogeneic hematopoietic stem cell transplantation. Persistent mixed chimerism develops in around 10% of transplanted thalassemic patients, but the biological mechanisms underlying this phenomenon are poorly understood.Design and Methods The presence of interleukin-10-producing T cells in the peripheral blood of eight patients with persistent mixed chimerism and five with full donor chimerism was investigated. A detailed characterization was then performed, by T-cell cloning, of the effector and regulatory T-cell repertoire of one patient with persistent mixed chimerism, who developed stable split erythroid/lymphoid chimerism after a hematopoietic stem cell transplant from an HLA-matched unrelated donor.Results Higher levels of interleukin-10 were produced by peripheral blood mononuclear cells from patients with persistent mixed chimerism than by the same cells from patients with complete donor chimerism or normal donors. T-cell clones of both host and donor origin could be isolated from the peripheral blood of one, selected patient with persistent mixed chimerism. Together with effector T-cell clones reactive against host or donor alloantigens, regulatory T-cell clones with a cytokine secretion profile typical of type 1 regulatory cells were identified at high frequencies. Type 1 regulatory cell clones, of both donor and host origin, were able to inhibit the function of effector T cells of either donor or host origin in vitro.Conclusions Overall these results suggest that interleukin-10 and type 1 regulatory cells are associated with persistent mixed chimerism and may play an important role in sustaining long-term tolerance in vivo. These data provide new insights into the mechanisms of peripheral tolerance in chimeric patients and support the use of cellular therapy with regulatory T cells following hematopoietic stem cell transplantation.

Gene therapy is a highly attractive strategy for many types of inherited disorders of the immune system. Adenosine deaminase (ADA) deficient-severe combined immunodeficiency (SCID) has been the target of several clinical trials based on the use of hematopoietic stem/progenitor cells engineered with retroviral vectors. The introduction of a low intensity conditioning regimen has been a crucial factor in achieving stable engrafment of hematopoietic stem cells and therapeutic levels of ADA-expressing cells. Recent studies have demonstrated that gene therapy for ADA-SCID has favorable safety profile and is effective in restoring normal purine metabolism and immune functions. Stem cell gene therapy combined with appropriate conditioning regimens might be extended to other genetic disorders of the hematopoietic system.

Background: We investigated the long-term outcome of gene therapy for severe combined immunodeficiency (SCID) due to the lack of adenosine deaminase (ADA), a fatal disorder of purine metabolism and immunodeficiency. Methods: We infused autologous CD34+ bone marrow cells transduced with a retroviral vector containing the ADA gene into 10 children with SCID due to ADA deficiency who lacked an HLA-identical sibling donor, after nonmyeloablative conditioning with busulfan. Enzyme-replacement therapy was not given after infusion of the cells. Results: All patients are alive after a median follow-up of 4.0 years (range, 1.8 to 8.0). Transduced hematopoietic stem cells have stably engrafted and differentiated into myeloid cells containing ADA (mean range at 1 year in bone marrow lineages, 3.5 to 8.9%) and lymphoid cells (mean range in peripheral blood, 52.4 to 88.0%). Eight patients do not require enzyme-replacement therapy, their blood cells continue to express ADA, and they have no signs of defective detoxification of purine metabolites. Nine patients had immune reconstitution with increases in T-cell counts (median count at 3 years, 1.07 x 10(sup 9) per liter) and normalization of T-cell function. In the five patients in whom intravenous immune globulin replacement was discontinued, antigen-specific antibody responses were elicited after exposure to vaccines or viral antigens. Effective protection against infections and improvement in physical development made a normal lifestyle possible. Serious adverse events included prolonged neutropenia (in two patients), hypertension (in one), central-venous-catheter-related infections (in two), Epstein-Barr virus reactivation (in one), and autoimmune hepatitis (in one). Conclusions: Gene therapy, combined with reduced-intensity conditioning, is a safe and effective treatment for SCID in patients with ADA deficiency. (ClinicalTrials.gov numbers, NCT00598481 and NCT00599781.) N Engl J Med 2009;360:447-58. RI rossi, paolo/D-6504-2012; galimberti, stefania/H-2594-2012 BACKGROUND:We investigated the long-term outcome of gene therapy for severe combined immunodeficiency (SCID) due to the lack of adenosine deaminase (ADA), a fatal disorder of purine metabolism and immunodeficiency.METHODS:We infused autologous CD34+ bone marrow cells transduced with a retroviral vector containing the ADA gene into 10 children with SCID due to ADA deficiency who lacked an HLA-identical sibling donor, after nonmyeloablative conditioning with busulfan. Enzyme-replacement therapy was not given after infusion of the cells.RESULTS:All patients are alive after a median follow-up of 4.0 years (range, 1.8 to 8.0). Transduced hematopoietic stem cells have stably engrafted and differentiated into myeloid cells containing ADA (mean range at 1 year in bone marrow lineages, 3.5 to 8.9%) and lymphoid cells (mean range in peripheral blood, 52.4 to 88.0%). Eight patients do not require enzyme-replacement therapy, their blood cells continue to express ADA, and they have no signs of defective detoxification of purine metabolites. Nine patients had immune reconstitution with increases in T-cell counts (median count at 3 years, 1.07x10(9) per liter) and normalization of T-cell function. In the five patients in whom intravenous immune globulin replacement was discontinued, antigen-specific antibody responses were elicited after exposure to vaccines or viral antigens. Effective protection against infections and improvement in physical development made a normal lifestyle possible. Serious adverse events included prolonged neutropenia (in two patients), hypertension (in one), central-venous-catheter-related infections (in two), Epstein-Barr virus reactivation (in one), and autoimmune hepatitis (in one).CONCLUSIONS:Gene therapy, combined with reduced-intensity conditioning, is a safe and effective treatment for SCID in patients with ADA deficiency. (ClinicalTrials.gov numbers, NCT00598481 and NCT00599781.) BackgroundWe investigated the long-term outcome of gene therapy for severe combined immunodeficiency(SCID) due to the lack of adenosine deaminase (ADA), a fatal disorderof purine metabolism and immunodeficiency.MethodsWe infused autologous CD34+ bone marrow cells transduced with a retroviral vectorcontaining the ADA gene into 10 children with SCID due to ADA deficiency wholacked an HLA-identical sibling donor, after nonmyeloablative conditioning withbusulfan. Enzyme-replacement therapy was not given after infusion of the cells.ResultsAll patients are alive after a median follow-up of 4.0 years (range, 1.8 to 8.0). Transducedhematopoietic stem cells have stably engrafted and differentiated into myeloidcells containing ADA (mean range at 1 year in bone marrow lineages, 3.5 to 8.9%)and lymphoid cells (mean range in peripheral blood, 52.4 to 88.0%). Eight patientsdo not require enzyme-replacement therapy, their blood cells continue to expressADA, and they have no signs of defective detoxification of purine metabolites. Ninepatients had immune reconstitution with increases in T-cell counts (median countat 3 years, 1.07×109 per liter) and normalization of T-cell function. In the five patientsin whom intravenous immune globulin replacement was discontinued, antigenspecificantibody responses were elicited after exposure to vaccines or viral antigens.Effective protection against infections and improvement in physical development madea normal lifestyle possible. Serious adverse events included prolonged neutropenia(in two patients), hypertension (in one), central-venous-catheter–related infections (intwo), Epstein–Barr virus reactivation (in one), and autoimmune hepatitis (in one).ConclusionsGene therapy, combined with reduced-intensity conditioning, is a safe and effectivetreatment for SCID in patients with ADA deficiency. (ClinicalTrials.gov numbers,NCT00598481 and NCT00599781.)

Abstract 666 Background: Results of haploidentical stem cell transplantation (SCT) after standard extensive T-cell depletion for advanced leukemias are poor (Ciceri et al, 2008). In contrast, significant leukemia-free-survivals are produced after T-cell replete SCT from matched related, unrelated and cord-blood donors, even in advanced phases of disease (Kolb HJ, 2009). New protocols based on T-cell repletion are warrented in patients receiving haplo-SCT, in order to offer to all candidates patients with advanced leukemia the potential of cure of allogeneic SCT.Rapamycin is an immunosuppressive drug that arrests cell cycle in G1 phase through the inhibition of DNA transcription, RNA translation and protein synthesis. Morover, in contrast to calcineurin inhibitors, it promotes the generation and expansion of T regulatory cells (Tregs). Aim: We investigated the safety of infusion of T-cell replete unmanipulated peripheral blood stem cells (PBSC) from family haploidentical donor with a combination Rapamycin, Mycophenolate and ATG as GvHD prophylaxis, to preserve early Treg function (TrRaMM study, Eudract 2007-5477-54). Patients and Methods: Since 2007, forty-six patients underwent allogeneic transplantation for AML (25 pts), ALL (7 pts), sAML (6 pts), MDS (3 pts), CML-BC (2 pts), NHL (2 pts) or HD (1 pt). The median age was 50 years (range 14-69). At time of transplantation 5 pts were in early phase, and 41 were in advanced phase. Median time from diagnosis to transplantation was 351 days (range 81-1387); 8 patients were enrolled for relapse after allogeneic SCT from MRD or MUD. Median comorbodity index score was 1 (0-5). The conditioning regimen included Treosulfan (14 g/m2 for 3 days), Fludarabine (30 mg/m2 for 5 days) and an in vivo T and B-cell depletion, by ATG-Fresenius (10 mg/kg for 3 times) and Rituximab (a single 500 mg dose). All pts received allogeneic peripheral blood cells from an HLA-haploidentical related donor without any in vitro positive selection of CD34+ cells. GvHD prophylaxis consisted of Rapamycin (target level 8-15 ng/ml, till day +60) and MMF (15 mg/kg tid till day +30). Results: All patients engrafted, and all but eight were in disease remission at first marrow evaluation on day +30. Cumulative incidence of grade 2-4 aGvHD was 33% (95% CI: 18-48); cumulative incidence of grade 3-4 aGvHD was 12% (95% CI: 2-22). Interestingly, half of patients with GvHD developed it at immunosuppressive prophylaxis withdrawal for disease relapse. Only six patients developed cGvHD. Cumulative incidence of TRM and relapse incidence were 26% (95% CI: 11-41) and 53% (95% CI: 35-71) respectively. None developed EBV reactivation. Patients experienced an early and sustained immunoreconstitution with a median 221 circulating CD3+cells/μL (range 43-1690) from day 30. The immune-reconstitution was polarized towards central memory cells (CD45RA-CD62L+ cells 32.7% ± 4.8) that produced IL-2 (IL-2+ cells 26.2% ± 5.3). Of interest, at day +90 from transplant, Tregs were significantly expanded (CD4+CD25+CD127-Foxp3+ cells 15.6% ± 4.8 on total CD3+ cells, P Conclusions: Rapamycin-Mycophenolate-ATG are effective to prevent GvHD in T-cell replete unmanipulated haploidentical peripheral stem cell transplantation for advanced haematological malignancies. This associates with an early T-cell immunoreconstitution characterized by the in vivo expansion of early-differentiated T cells and Tregs, and translates in promising leukemia-free survival in patients with advanced resistant leukemia. Further studies are warranted to gain insight on the role of rapamycin as platform for exploitation of Tregs in allogeneic HSCT from mismatched donor. Disclosures: No relevant conflicts of interest to declare.

There is a substantial incidence of graft failure in patients with thalassemia after myeloablative conditioning regimens especially in class 3 patients in whom its incidence could be as high as 8-38.5%. Most patients with graft failure have recurrence of thalassemic marrow. Historically, results of second transplants for thalassemia were poor because of a high rejection rate and/or increased TRM. Sixteen patients with thalassemia recurrence following rejection of the first graft and with a median age of 9 years (range, 4-20) were given second transplants using BM (n = 7) or PBSC (n = 9) after preparation with a new treatment protocol. All but two patients received stem cells from the same donor. The median interval between two transplants was 28 months (range, 8-204). The sustained engraftment rate was high (94%) with only one patient having primary graft failure. The probability of overall survival, event-free survival, TRM and graft failure were 79, 79, 16 and 6%, respectively. There were three transplant-related deaths. Thirteen patients are alive with Lansky/Karnofsky score of 100. This intensified treatment protocol was well tolerated with no significant increase in toxicity. The excellent results obtained with this new preparative regimen allow us to recommend it for second transplantation for patients with thalassemia recurrence.

Allogeneic BMT represents the only chance of cure for beta-thalassemia. Occasionally, two affected individuals from the same family share a matched healthy sibling. Moreover, a high incidence of transplant rejection is still observed in Pesaro class III patients, requiring a second BMT procedure. In these settings, one option is to perform a second BM harvest from the same donor. Although BM harvest is a safe procedure in children, ethical issues concerning this invasive practice still arise. Here, we describe our series of seven pediatric, healthy donors, who donated BM more than once in favor of their beta-thalassemic HLA-identical siblings between June 2005 and January 2008. Three donors donated BM twice to two affected siblings and four donors donated twice for the same sibling following graft rejection of the first BMT. All donors tolerated the procedures well and no relevant side effects occurred. There was no significant difference between the two harvests concerning cell yield and time to engraftment. Our experience shows that for pediatric donors, a second BM donation is safe and feasible and good cellularity can be obtained. We suggest that a second harvest of a pediatric donor can be performed when a strong indication for BMT exists. Allogeneic BMT represents the only chance of cure for beta-thalassemia. Occasionally, two affected individuals from the same family share a matched healthy sibling. Moreover, a high incidence of transplant rejection is still observed in Pesaro class III patients, requiring a second BMT procedure. In these settings, one option is to perform a second BM harvest from the same donor. Although BM harvest is a safe procedure in children, ethical issues concerning this invasive practice still arise. Here, we describe our series of seven pediatric, healthy donors, who donated BM more than once in favor of their beta-thalassemic HLA-identical siblings between June 2005 and January 2008. Three donors donated BM twice to two affected siblings and four donors donated twice for the same sibling following graft rejection of the first BMT. All donors tolerated the procedures well and no relevant side effects occurred. There was no significant difference between the two harvests concerning cell yield and time to engraftment. Our experience shows that for pediatric donors, a second BM donation is safe and feasible and good cellularity can be obtained. We suggest that a second harvest of a pediatric donor can be performed when a strong indication for BMT exists.

Gene therapy is a promising therapeutic strategy for genetic and acquired hematologic diseases. With the improvements in gene transfer and expression, factors affecting safety and efficacy of gene therapy can now be evaluated to establish the best clinical benefit-to-risk ratio. The induction of immune responses against gene therapy components is one of the potential limitations. We studied the occurrence of such event in 23 patients treated with donor lymphocyte infusions DLIs), with lymphocytes transduced to express the HSV-TK suicide gene for relapse of hematologic malignancies occurring after allogeneic hematopoietic stem cell transplantation (HSCT). The suicide gene was used to selectively control graft-versus-host disease (GvHD). Seven patients given infusions late after HSCT developed an immune response against the transgene. Immunization involved appearance of thymidine kinase (TK)-specific CD8(+) effectors and required a level of immunocompetence at the time of TK-DLI that can be achieved only several months after transplantation. This did not prevent graft-versus-leukemia (GvL) effect of the TK-DLI, since 5 of 7 immunized patients maintained the complete remission achieved prior to immunization. We suggest that appropriate study designs taking into account the immune suppression of the patient and time-kinetics of GvL mediated by TK-transduced donor lymphocytes may allow the full exploitation of TK-DLI. Gene therapy is a promising therapeutic strategy for genetic and acquired hematologic diseases. With the improvements in gene transfer and expression, factors affecting safety and efficacy of gene therapy can now be evaluated to establish the best clinical benefit-to-risk ratio. The induction of immune responses against gene therapy components is one of the potential limitations. We studied the occurrence of such event in 23 patients treated with donor lymphocyte infusions DLIs), with lymphocytes transduced to express the HSV-TK suicide gene for relapse of hematologic malignancies occurring after allogeneic hematopoietic stem cell transplantation (HSCT). The suicide gene was used to selectively control graft-versus-host disease (GvHD). Seven patients given infusions late after HSCT developed an immune response against the transgene. Immunization involved appearance of thymidine kinase (TK)-specific CD8(+) effectors and required a level of immunocompetence at the time of TK-DLI that can be achieved only several months after transplantation. This did not prevent graft-versus-leukemia (GvL) effect of the TK-DLI, since 5 of 7 immunized patients maintained the complete remission achieved prior to immunization. We suggest that appropriate study designs taking into account the immune suppression of the patient and time-kinetics of GvL mediated by TK-transduced donor lymphocytes may allow the full exploitation of TK-DLI.

Introduction Haematopoietic stem cell transplantation (HSCT) is the only curative option for patients (pts) affected by high-risk haematological diseases (HRHD). However, the availability of a match donor is still an unmet-medical need. Recently alternative donor transplantations have been broadly exploited, reaching results similar to transplants from a well match donor. Anyway, whoever the donor is, the most important complication remains Graft-versus-Host Disease (GvHD). Aim of the study We evaluated incidence, characterization, stratification, treatment, treatment response and outcome at medium and long-term follow-up for both acute (a-) and chronic (c-) GvHD in haploidentical setting. We also evaluated the impact of the NIH consensus criteria on GvHD in a routine clinical application to confirm their feasibility in daily practice and not only in clinical trials use. Methods A population of 257 pts was selected from our Institutional database on the basis of their having an HRHD with indication to allogeneic HSCT and having received a HSCT from an haploidentical family donor without exclusion. HSCT were performed between January 2004 and December 2013 at our Center. No distinction between first HSCT or subsequent one was made, all consecutive haploidentical HSCT were captured. Results Time of median follow-up was 10 months; 1-year overall-survival (OS) was 46%, with better outcome for pts transplanted in complete remission (p 0.0001) confirming disease status as the leading factor for overall outcome. Transplant related mortality was estimated to be 30% at 1 year and the leading cause of death was infections. The 6-months a-GvHD incidence was 45% (119/257) - median day of presentation 21 post HSCT (range 8-89). Late-onset a-GvHD was documented in 15 pts. Grade I GvHD was documented in 33 pts (27.7%), grade II in 44 (37%), grade III-IV in 36 (30.3%) – 6 not evaluable. Skin was the most frequently involved organ (77.3%), both as single manifestation or combined. One-hundred and five pts received a first line therapy based on high-dose prednisone (2mg/Kg) and 37/105 completely abrogated the a-GvHD. At a 3-months evaluation 46% of affected pts showed complete resolution of a-GvHD, while the mortality rate was 29%. C-GvHD affected 69/257 pts and 1-year risk of onset was 25% - median day of presentation was 139 post HSCT (range 40-809) and 36/69 pts were off immunosuppressive therapy (52.3%) at presentation. According to onset presentation 53.7% were de novo, 24.6% progressive and 18.8% quiescent GvHD. Forty-one pts (59.5%) presented at declaration with overlap features. The most frequent involved organ was skin (grade I to III), as reported in 53 pts (76.8%). Skin lesions were usually accompanied with mouth lesions (35 pts – 50.7%), liver (23 pts – 33.3%) or eyes (27 pts – 39.1%) dysfunctions. The median number of involved organs was 3 (range 1-7). Mild c-GvHD was diagnosed in 10 pts (14.5%), who received topical therapy. Fifty-nine pts – diagnosed with moderate (32, 46.4%) or severe (27, 39.1%) - received a systemic treatment for c-GvHD: prednisone 1 mg/Kg alone or 0,5 mg/kg plus mTOR- or calcineurin-inhibitor for pts that were not likely to tolerate high dose steroid due to comorbidity (namely active infections, diabetes, cardiovascular diseases). At a 12-months evaluation the overall response was 48% (complete resolution 25%, partial resolution 23%), while the mortality rate was 36%. The Landmark analysis of OS at 3 months after HSCT shows that a-GvHD affected pts had a worse outcome (p= 0,068), on the contrary the Landmark analysis of OS at 18 months shows that c-GvHD did not associate with a worse outcome (p ns) but the follow up is still short. Confirming previous reports, overlap c-GvHD was related to worse survival in comparison with classic c-GvHD (p 0.0098). Conclusion Haploidentical HSCT is a valid and feasible option for pts in need of a transplant. GvHD is manageable after haploidentical HSCT, as in full matched setting. Better knowledge and insight in a/c-GvHD are providing advance in improving pts outcome. The NIH-consensus criteria are manageable in daily clinical practice and able to translate in a tailored approach to GvHD with benefit on general outcome. Further advance in the development of specific biomarkers for GvHD will provide additional crucial information for management, diagnosis and prognostication in GvHD. Figure 1 Figure 1. Disclosures Bonini: MolMed S.p.A.: Consultancy. Bordignon:MolMed: Employment.

Introduction: The T cell memory compartment is multi-faceted and encompasses multiple subsets with divergent properties. In addition to central memory (TCM) and effector memory (TEM) cells, the spectrum of immunological memory has been recently extended with the identification of memory stem T cells (TSCM). Gene expression profiling, corroborated by in vitro and in vivo experimental results, posits TSCM upstream TCM and TEM in T-cell ontogeny. However, TSCM role in immune reconstitution (IR) following allogeneic HSCT remains largely unknown. Here, we tracked TSCM dynamics in patients undergoing haploidentical HSCT. By this process, we unconventionally exploited HSCT as model system to provide novel insights into the contribution of TSCM to a mounting immune response. Patients and Methods: We characterized T cell dynamics during the first month post HSCT in 20 patients receiving myeloablative conditioning, T-replete haploidentical peripheral blood stem cell graft, and GvHD prophylaxis consisting of cyclophosphamide (PT-Cy day 3,4), MMF and sirolimus from day 5. Results: Upon infusion, naïve T cells (TN) cells gradually disappeared from circulation, and by day 8 post HSCT the peripheral compartment was composed only by memory lymphocytes. At day 8, TSCM cells were the most represented circulating subset, and their frequency was significantly higher than that of the infused graft (LK). To investigate whether such high TSCM frequency was due to expansion of TSCM cells infused or to their direct in vivo generation, T cell subset proliferation was analyzed. At day 3 upon infusion (in the absence of immunosuppression), all memory subsets robustly proliferated, with TSCM cells displaying significantly higher frequencies of Ki-67+ cells compared to all other subsets. In sharp contrast, TN cells were scantly Ki-67+, in line with the longer timeframe required for their priming. PT-Cy abrogated proliferation in all subsets. T cell counts however did not drop between day 5 and 8 post HSCT, and TSCM cells increased in percentages and absolute numbers. We thus explored whether TSCM cells were resistant to PT-Cy, but failed to record ALDH activity, the major mechanism of Cy inactivation, in CD3+ cells. neither within LK nor upon infusion. Accordingly, we detected high percentages of apoptotic cells within all memory subsets at day 5 post HSCT. Nonetheless, at day 8 significantly lower percentages of TSCM cells were Annexin V+ compared to TCM/TEM, while by day 15 post-HSCT all memory subsets displayed very low levels of apoptosis. Thus, we reasoned that direct conversion of TN into TSCM could be the preferential mechanism underlying TSCM expansion. To prove this, we exploited the TCR sequences harbored by each individual T cell as surrogate clonal markers. Purified T cell subsets from LK and harvested 30 days post HSCT in 3 consecutive patients were subjected to TCR sequencing. Sequences harbored by LK-TN were retrieved in all memory subsets at day 30 after HSCT, showing that TN were able to generate the complete spectrum of immunological memory, including TSCM. Quantitative analysis revealed that only clonotypes originally harbored by LK-TN were significantly increased in counts at day 30 post-HSCT. In contrast, sequences unique to LK-TSCM, LK-TCM or LK-TEM were similar or reduced in counts at day 30 post-HSCT compared to LK, indicating that either PT-Cy efficiently dampened their expansion and/or that such memory lymphocytes persisted unchallenged upon in vivo infusion. Overall, in vivo fate mapping through TCR sequencing allowed defining the in vivo differentiation landscapes of human naïve T cells upon HSCT, highlighting TSCM as privileged players in the diversification of immunological memory. We next validated these results at the antigen-specific level. In suitable 5 patients, we recorded the presence of WT1 or PRAME-specific TN cells within donor LK. Upon HSCT, tumor-specific T cells increased in frequency and displayed a memory phenotype, comprising TSCM. Finally, by quantifying patient serum cytokines, we found that the degree of IL-7 availability at day 1 post HSCT correlated with the extent of TSCM expansion at day 8. Conclusions: These data provide novel insights into TSCM biology and ongoing analyses will define correlations with clinical events. Longer immunological follow-up will advance our understanding of the contribution of early TSCM generation to the overall success of post HSCT IR. Disclosures Bordignon: MolMed: Employment. Bonini:MolMed S.p.A.: Consultancy.

Introduction Complex Karyotype (CK), monosomy of chromosome 7 or 5 and Monosomal Karyotype (MK) are associated with a dismal outcome in Acute Myeloid Leukemia (AML) patients (pts). Allogeneic stem cell transplantation (allo-SCT) can be considered the only potentially curative option for these pts. Conventional allo-SCT strategies confer long term Overall Survival (OS) of around 20%. No data are available on the role of haploidentical stem cell transplantation (haplo-SCT) in this high risk setting. We reviewed our experience to address this issue. Patients and methods This retrospective analysis included adult AML pts treated at San Raffaele Hospital. Between November 2001 and April 2014, 33 consecutive pts with poor cytogenetic risk AML with monosomy of chromosome 7 or 5 (12/33 pts), MK (3/33 pts) and CK (18/33 pts) received haplo-SCT. Karyotypes were obtained from diagnostic bone marrow samples with standard methods and in accordance with International System of Human Cytogenetic Nomenclature guidelines. OS and Disease Free Survival (DFS) were calculated using the Kaplan-Meier product-limit method. Results Median age of pts at transplant was 50 years (range, 22 to 65). At the time of haplo-SCT, 10 pts (30%) were in complete remission (8 were in first complete remission), while 23 (70%) had active disease. Patients received a myeloablative conditioning regimen, Treosulfan-based. Twenty seven out of 33 pts received a T-cell repleted haplo-SCT, 6 pts a T-cell depleted haplo-SCT. In those pts who received a T-cell repleted transplant, GvHD prophylaxis was based on Cyclosporin and Methotrexate (7/27 cases) or Rapamycine and Mycophenolate Mofetil (20/27 cases). All 27 pts received Antithymocyte Globulin. Median follow-up after haplo-SCT was 304 days (range, 5 to 2897 days). Of 33 pts, 30 (91%) were in CR at day +30 after transplant, 1 died of sepsis before disease evaluation, 2 had disease persistence. At the last follow-up 11 out of 33 pts (34%) were alive, all of whom in CR, 22 pts (66%) died for the following causes: disease relapse/progression 10 (45%), Graft versus Host Disease 3 (14%), infection 9 (41%). Transplant related mortality (TRM) was 35.2% at 1 year and 35.2% at 3 years after transplant. Extimated DFS from day 30 after transplant was 34.5% at 1 year and 28% at 3 years. Extimated OS for all pts was 45% at 1 year and 22.6% at 3 years. Discussion Our data support haplo-SCT as a potentially curative option for AML pts with high risk cytogenetic abnormalities. Despite a TRM of 35% at 3 years, 1/3 of these pts achieved a long term disease free status. In the setting of a disease with extremely poor therapeutic options, haplo-SCT appears promising and not inferior to other sources of allogeneic stem cell transplantation. Transplantation strategies aimed at reducing transplant related mortality or disease relapse should be explored in order to improve these results and achieve a better outcome. Disclosures No relevant conflicts of interest to declare.

BACKGROUND: Human herpesvirus type 6 (HHV-6) is increasingly recognized as an opportunistic and potentially life-threatening pathogen in recipients of allogeneic hematopoietic stem cell transplantation (AlloSCT). HHV-6 is a member of the beta herpesvirus subfamily (genus Roseolovirus). HHV-6 infection is recognized as the cause of a febrile disease and exanthem subitum in early childhood. Approximately 60% of solid organ transplant and 40% of patients after alloSCT experienced HHV-6 reactivation. Reported clinical manifestations of HHV-6 infection in transplanted patients are skin rash, interstitial pneumonia, bone marrow suppression and encephalitis. Moreover, some clinical reports suggest that HHV-6 can facilitate the occurrence of severe clinical complications of alloSCT, increasing transplant-related mortality. METHODS: From January 2009 to February 2013, we retrospectively evaluated 54 consecutive adult patients (median age 50 years) who developed positivity to HHV-6 after alloSCT for high-risk hematological malignancies. Stem cell donors were family haploidentical (37), HLA identical sibling (8), unrelated volunteer (6), cord blood (3). The viral load was determined by quantitative PCR (Nanogen Advanced Diagnostic S.r.L) in cell-free body fluids such as plasma, bronchoalveolar lavage (BAL), cerebrospinal fluid (CSF), bone marrow (BM) aspirates or in gastrointestinal biopsies. RESULTS: Median time from alloSCT to HHV-6 reactivation was 34 days (range: 0-705). Thirty-one patients presented HHV-6 positive in plasma, 9/54 in BM, 33/54 in gut biopsies or BAL, 7/54 in CSF. At the time of viral positivity all pts were receiving acyclovir as viral prophylaxis except five. Twenty-nine patients had acute graft versus host disease (GvHD). Twenty-two out of these twenty-nine patients experienced a grade III-IV acute GvHD, requiring high dose steroids in twenty-six cases. A concomitant CMV positivity was detected in 15/54 patients. The median absolute count of CD3+ lymphocytes was 207 cells/mcl. In 52/54 cases we reported HHV-6 clinical manifestations: fever (43), skin rash (22), hepatitis (19), diarrhoea (24), encephalitis (10), BM suppression (18), delayed engraftment (11). HHV-6 positivity led to antiviral pharmacological treatment in 37/54 cases, using as first choice therapy foscarnet. Amongst the total fifty-four patients with documented HHV-6 positivity thirty-one solved the clinical event. However the mortality rate was relatively high in this population (overall survival (OS) ±SE at 1 year after HHV-6 reactivation was 38% ± 7%), mainly related to severe infections or GvHD. A better OS is significantly associated with CD3+ cells ≥200/mcl at the time of HHV-6 reactivation (fig 1) (OS at 1 year 63% compared to 11% for patients with CD3 CONCLUSIONS: This retrospective study confirms a correlation of HHV-6 with high morbidity and mortality rates after alloSCT, thus suggesting a regular HHV-6 monitoring in alloSCT recipients. The regular monitoring of HHV-6 DNA, using a real-time PCR assay, may be useful for identifying active HHV-6 infection and for the introduction of a pre-emptive treatment, possibly reducing the incidence of the most severe clinical complications. Despite HHV-6 detection typically occurred early after alloSCT, a better immune reconstitution has the potential to improve clinical outcome. Figure 1: Overall survival after alloSCT in HHV-6 positive patients: green line showed patients with more than 200/mcl CD3+ cells, blue line the ones with less than 200/mcl CD3+ cells at HHV-6 reactivation. P value is provided by Log Rank test. Figure 1:. Overall survival after alloSCT in HHV-6 positive patients: green line showed patients with more than 200/mcl CD3+ cells, blue line the ones with less than 200/mcl CD3+ cells at HHV-6 reactivation. P value is provided by Log Rank test. Disclosures Bonini: MolMed S.p.A.: Consultancy.

Introduction:Haploidentical hematopoietic stem cell transplantation (HSCT) performed using T–replete BM grafts and post-transplantation cyclophosphamide (PT-Cy) has gained much interest in the transplantation community for the excellent toxicity profile, achieving outcomes equivalent to those of HSCT performed using matched related or unrelated donors (Bashey, JCO 2013). Nonetheless, relapse remains a major challenge with the use of this non-myeloablative regimen (Luznik, BBMT 2008). Thus, we investigated whether the use of PBSC graft, an intensified myeloablative conditioning and sirolimus instead of tacrolimus might help increasing the therapeutic index of this procedure. Patients and Methods:Here we report the results on 39 patients treated between Nov 2012 and June 2014. The median age was 56 years (range, 21–78). Diagnoses included AML (21), ALL (5), CML-BC (1), MDS (1), NHL (5), and HD (6). The majority (62%) of patients were not in disease remission at time of HSCT. Eight patients (20%) received a prior allo-HSCT. For the remaining patients who underwent haplo-PTCy as a first allogeneic transplant, 19 patients (61%) scored high/very high according to the CIBMTR disease score, 12 (39%) scored intermediate, while no patient had a low disease score. The median Sorror Comorbidity Index was 3 (range: 0-9). Conditioning consisted of treosulfan (14 g/m2/day) on days –6 to –4, fludarabine (30 mg/m2/day) on days –6 to –2, and melphalan (70 mg/m2/day) on days –2 and –1, followed by T-replete G-CSF-mobilized PBSC. Postgrafting immunosuppression consisted of PT-Cy (50 mg/kg/day) on days 3 and 4, followed by mycophenolate mofetil for 30 days, and sirolimus for at least 3 months. Overall survival (OS) and disease-free survival (DFS) were estimated using the Kaplan-Meier method. Cumulative incidence (CI) of non-relapse mortality (NRM) was calculated using relapse as a competing risk, for GvHD the competing risk was death. Results:PBSC grafts contained an infused median CD34/kg of 6.03 e6 (4.15–8.02 e7), CD3/kg 21.12 e7 (10.5–48.26 e7). All patients but 1 engrafted (97.5%), with a median time to neutrophil and platelet recovery of 18 days (range 13–45) and 19 days (9–65), respectively. Notably, the only patient with primary graft failure had a HLA-DP mismatch in HvG direction. Post-HSCT recovery of lymphocyte subsets was broad and fast: median time to CD3>100/ml was 28 days (range: 8-97), to CD4>200/ml 35 days (21-137) and to CD19>0/ml 34 days (24-137). Circulating T cells comprised naïve and memory subsets, with a recovery of CD31+ recent thymic emigrants (RTEs) starting from day 30. All patients had a significantly higher proportion of circulating RTEs at day 30, 90 and 180 compared to their pre-HSCT levels, suggesting an improvement in their thymic function after HSCT. We observed a significant early increase in circulating Tregs at day 15 post HSCT. With a median follow-up for living patients of 327 days, the 1-year cumulative CI of NRM and relapse were 15% and 32%, respectively. Two of the 9 relapses were HLA-loss variants (Vago, NEJM 2009) occurring at a median time of 277 days post-HSCT. Classical relapses had instead an earlier occurrence (median time to relapse: 92 days, range 37-134). CI of acute GvHD grade II-IV and III-IV at 6 months were 18% and 8%, while CI of chronic GvHD at 12 months was 19%. Estimated 1-year probability of OS and DFS were 58% and 51%. Outcomes were particularly favorable in patients transplanted in CR (1-year OS 93%, DFS 95%) as compared to those of patients transplanted with active disease (1-year OS 37%, DFS 29%; p=0.005 and p=0.001, respectively). Importantly, stratification according to CIBMTR score held similar results: in patients with intermediate score, 1-year OS was 91% vs. 33% in patients with high/very high score (p=0.015); similarly, 1-year DFS was 92% vs. 34% (p=0.009). Conclusions: PT-Cy coupled to sirolimus allow the use of haploidentical PBSC grafts with low rates of GvHD, and intensified myeloablative regimen is a valid option for patients with aggressive/advanced hematologic malignancies. The acceptable rates of GvHD and NRM as well as the favorable immune reconstitution profile open the way for combining it with novel immunomodulatory or cellular therapies to improve DFS in patients at high risk for relapse who would benefit from further treatment intensification early after transplant. Disclosures Bonini: MolMed S.p.A.: Consultancy.

BACKGROUND: Febrile neutropenia and sepsis are frequent and life-threatening complications in patients with haematological malignancies. Although the proportion of infectious deaths in haematological patients has decreased over the last two decades, much remains to be done to further reduce these events. More effective preventive and prophylactic strategies for high-risk patients are necessary. Blood cultures (BC) identify a pathogen in only 20 to 30% of febrile episodes, the culturing and pathogen identification process is lengthy, postponing the start of a pathogen-targeted treatment. Thereby, a sensitive tool to promptly recognize pathogens causing sepsis is of high clinical relevance. METHODS: We assessed the diagnostic usefulness of the LightCycler SeptiFast test (SF; Roche Molecular Systems), a PCR-based multiplex assay performed on peripheral blood and capable of detecting 25 among the most common species isolated in sepsis. The assay uses dual fluorescent resonance energy transfer (FRET) probes against the species-specific internal transcribed spacer (ITS) regions, a non-coding sequence interspaced among highly conserved bacterial and fungal RNA. Time from processing to result is remarkably short (less than 6 hours). In this study, blood samples from febrile haematological patients were concomitantly tested by traditional blood culture (BacT/Alert 3D; bioMerieux). RESULTS: A total of 1941 blood samples were collected from 516 consecutive haematological patients treated for febrile neutropenia at the San Raffaele Haematology and Bone Marrow Transplantation Unit, from 2009 to 2013. Out of the total 1941 episodes examined, positive results were detected in 537 samples by SF (28%), and in 263 by BC (14%). Together, the two methods identified a total of 586 microorganisms in 509 (26%) episodes: Gram-positive bacterial species (80%), Gram-negative bacterial species (17%), and fungal species (3%). Concordance between the two methods was 77%, with most of the discordant samples that tested negative by culture but positive using the molecular approach (50% of the total positive samples). The cases positive by SF alone were mostly samples from patients already receiving antimicrobial therapy, or, importantly, sample positive for fungal pathogens such as Aspergillus fumigatus, which is hard to detect by the traditional approaches. CONCLUSION: This analysis demonstrates a significant correlation between the molecular test and the standard BC in haematological patients with febrile neutropenia. A molecular test such as SF, in combination with traditional assays, can play an important role in the diagnosis of sepsis, particularly in persistent fever despite antibacterial therapy, when a non-responding bacterial infection or an invasive fungal infection is suspected, therefore leading to a rapid diagnosis and an earlier targeted antimicrobial therapy. Disclosures No relevant conflicts of interest to declare.

The importance of HLA-DPB1 matching for the outcome of allogeneic hematologic stem cell (HSC) transplantation is controversial. We have previously identified HLA-DPB1*0901 as a target of cytotoxic T cells mediating in vivo rejection of an HSC allograft. Here we show that HLA-DPB1*0901 encodes a T-cell epitope shared by a subset of DPB1 alleles that determines nonpermissive mismatches for HSC transplantation. Several T-cell clones obtained from the patient at the time of rejection showed HLA-DP restricted recognition of allogeneic targets expressing HLA-DPB1*0901, *1001, *1701, *0301, *1401, and *4501, but not other alleles. Based on these findings, we developed an algorithm for prediction of nonpermissive HLA-DPB1 mismatches. Retrospective evaluation of 118 transplantations showed that the presence of nonpermissive HLA-DPB1 mismatches was correlated with significantly increased hazards of acute grade II to IV graft-versus-host disease (HR = 1.87, P =.046) and transplantation-related mortality (HR = 2.69, P = .027) but not relapse (HR = 0.98, P = .939), as compared with the permissive group. There was also a marked but statistically not significant increase in the hazards of overall mortality (HR = 1.64, P = .1). These data suggest that biologic characterization of in vivo alloreactivity can be a tool for definition of clinically relevant nonpermissive HLA mismatches for unrelated HSC transplantation. RI apperley, jane/B-4367-2009

The acquisition of additional cytogenetic changes (clonal evolution, CE) during treatment of chronic myeloid leukemia (CML) with imatinib mesylate is currently regarded as an index of increasing resistance to imatinib. Therefore, to investigate whether CE as an isolated event increases the risk of disease progression during imatinib treatment, we compared the outcome of patients with CML in chronic phase (CML-CP) who developed CE whilst in complete hematologic remission with the outcome of comparable patients in complete hematologic remission who showed no evidence of CE.We serially studied cytogenetic findings in 102 patients receiving the Abl-tyrosine kinase inhibitor, imatinib mesylate, as sole agent to treat CML-CP who had no evidence of CE before initiation of imatinib treatment.CE was identified during treatment with imatinib in 15 patients, 10 of whom were in complete hematologic remission. In most cases these changes occurred exclusively in the Ph+ population but in three patients additional changes occurred in a co-existing Ph-negative population. Patients with de novo CE in the absence of any other sign of disease progression had a significantly higher incidence of progression by 18 months than did non-CE patients (progression-free survival 34.3% (CI 10.5-69.8%) vs. 94.1% (CI 80.6-98.4%), p0.0001).Based on this relatively small series of patients, we conclude that acquisition of clonal evolution increases the risk of subsequent disease progression also in CML patients in complete hematologic remission on imatinib.

We have previously shown that the infusion of donor lymphocytes expressing the herpes simplex virus thymidine kinase (HSV-tk) gene is an efficient tool for controlling graft-versus-host disease (GVHD) while preserving the graft-versus-leukemia (GVL) effect. In addition to the GVL effect, the administration of donor HSV-tk(+) cells could have a clinical impact in promoting immune reconstitution after T-cell-depleted stem cell transplantation (SCT). To explore this hypothesis, we have investigated whether in vitro polyclonal activation, retroviral transduction, immunoselection, and expansion affect the immune competence of donor T cells. We have observed that, after appropriate in vitro manipulation, T cells specific for antigens relevant in the context of SCT are preserved in terms of frequency, expression of T-cell receptor, proliferation, cytokine secretion, and lytic activity. A reduction in the frequency of allospecific T-cell precursors is observed after prolonged T-cell culture, suggesting that cell manipulation protocols involving a short culture time and high transduction efficiency are needed. Finally, the long-term persistence of HSV-tk(+) cells was observed in a patient treated in the GVL clinical trial, and a reversion of the phenotype of HSV-tk(+) cells from CD45RO(+) to CD45RA(+) was documented more than 2 years after the infusion. Based on all this evidence, we propose a clinical study of preemptive infusions of donor HSV-tk(+) T cells after SCT from haploidentical donors to provide early immune reconstitution against infection and potential immune protection against disease recurrence. (C) 2003 by The American Society of Hematology. We have previously shown that the infusion of donor lymphocytes expressing the herpes simplex virus thymidine kinase (HSV-tk) gene is an efficient tool for controlling graft-versus-host disease (GVHD) while preserving the graft-versus-leukemia (GVL) effect. In addition to the GVL effect, the administration of donor HSV-tk(+) cells could have a clinical impact in promoting immune reconstitution after T-cell-depleted stem cell transplantation (SCT). To explore this hypothesis, we have investigated whether in vitro polyclonal activation, retroviral transduction, immunoselection, and expansion affect the immune competence of donor T cells. We have observed that, after appropriate in vitro manipulation, T cells specific for antigens relevant in the context of SCT are preserved in terms of frequency, expression of T-cell receptor, proliferation, cytokine secretion, and lytic activity. A reduction in the frequency of allospecific T-cell precursors is observed after prolonged T-cell culture, suggesting that cell manipulation protocols involving a short culture time and high transduction efficiency are needed. Finally, the long-term persistence of HSV-tk(+) cells was observed in a patient treated in the GVL clinical trial, and a reversion of the phenotype of HSV-tk(+) cells from CD45RO(+) to CD45RA(+) was documented more than 2 years after the infusion. Based on all this evidence, we propose a clinical study of preemptive infusions of donor HSV-tk(+) T cells after SCT from haploidentical donors to provide early immune reconstitution against infection and potential immune protection against disease recurrence. (C) 2003 by The American Society of Hematology.

The new Abl tyrosine kinase inhibitor imatinib (imatinib mesylate, STI571) is very effective in the treatment of patients with chronic myeloid leukemia (CML). It induces complete hematologic control in90% of patients with CML in chronic phase and preliminary data suggest that the incidence of complete cytogenetic remission may exceed 60% in previously untreated patients, though its capacity to prolong life in comparison with other agents has not yet been clearly established. It is also active in the management of patients in advanced phases of CML.We present here provisional indications for the use of imatinib in CML patients and give details of the dosage regimens we have used and side-effects we have encountered.It is likely that the optimal usage of this important new agent will become better defined as more experience is gained.

Donor lymphocyte infusion (DLI) can restore durable molecular remission in a high percentage of patients with chronic myeloid leukemia (CML) who have relapses after allogeneic stem cell transplantation, but for patients who do not respond survival is poor. Imatinib mesylate (STI571) is a specific inhibitor of BCR-ABL tyrosine kinase that can induce hematologic and cytogenetic remissions in patients with CML. We report here a male patient who had a relapse to chronic phase after stem cell transplantation for CML, did not benefit from treatment with DLI, and then was administered STI571 at a dose of 400 mg daily. There was a rapid, complete hematologic response, and complete restoration of donor-type hematopoiesis (100% 46, XX marrow metaphases) was achieved after 6 months of therapy, though RT-PCR studies still detected BCR-ABL transcripts in the blood at low level. This case demonstrates that imatinib mesylate can be highly effective in the management of patients who have relapses after allograft for CML.

Background Hematopoietic stem cell transplantation (HSCT) is so far the only potentially curative option for patients with aggressive hematological malignancies. Since many patients cannot find a suitable HLA-identical (related or unrelated) donor, it is essential to analyze the safety of alternative graft sources, such as haploidentical donors. The use of reduced-intensity conditioning regimens in patients with an advanced disease did not improve the outcome because of a higher incidence of relapse. Here we present an interim analysis of this phase II prospective clinical trial that investigates a new conditioning regimen for allogeneic HSCT based on a well established one (Fludarabine and Treosulfan) intensified adding 4 Gy TBI with the aim of maintaining an acceptable toxicity profile while reducing the incidence of relapse in high-risk patients (TrRaMM4Gy study, Eudract 2011-001534-42). Patients and Methods Ninety-six patients underwent allogeneic HSCT for AML (n=46), ALL (n=13), acute biphenotypic leukaemia (n=2), HD (n=8), NHL (n=7), MDS (n=6), Myelofibrosis (n=5), MM (n=4), CML (n=2), CMML (n=2) or CLL (n=1). The median age was 45 years (range 17-67). At the time of the transplantation most patients (n=76) were in advanced disease phase, while the remaining 20 patients were in early phase. Twenty-eight patients were enrolled for relapse after a previous allogeneic HSCT. Median time from diagnosis to transplantation was 443 days (range 56-5249). Median comorbodity index score (according to Sorror criteria) was 2 (range: 0-8). Sixty-two patients received the graft from haploidentical donors, 17 from MUD, 14 from HLA-identical sibling and 3 patients from a single cord blood unit. Median number of CD34+ and CD3+ cells/kg were 6.46 millions and 241 millions respectively. The conditioning regimen included Treosulfan (14 g/m2 for 3 days), Fludarabine (30 mg/m2 for 5 days) and 4 Gy TBI split in 2 fractions. Patients receiving HSCT from haploidentical donor (arm A) were also treated with ATG-Fresenius (10 mg/kg for 3 days) and Rituximab (200 mg/m2 in single dose), patients receiving HSCT from HLA-identical sibling, MUD or single cord blood unit and in early disease status (arm B) were also treated with ATG-Fresenius (5 mg/kg for 3 days) and Rituximab (200 mg/m2 in single dose), while patients receiving HSCT from HLA-identical sibling, MUD or single cord blood unit and in advanced disease status (arm C) did not receive any ATG or Rituximab. GvHD prophylaxis consisted of Sirolimus (target concentration 8-15 ng/ml, till day +60) and Mycophenolate Mofetil (10 mg/kg tid till day +30). Results Neutrophils engraftment was reported at a median time of 17 days (range: 9-46) in all 91 evaluable patients; five patients died of transplant-related causes (n=4) or disease progression (n=1) before day +15. Platelets engraftment occurred after a median time of 17 days (range: 4-153) in 75 patients (82%). At the first marrow evaluation on day +30 all the evaluable patients showed full donor chimerism, 77 patients (90%) were in complete remission and 9 were in stable disease or progression. After a median follow-up of 425 days, cumulative incidence of grade 2-4 and 3-4 aGvHD were 40% and 26% respectively. Cumulative incidence of moderate or severe cGvHD (according to NIH criteria) was 57%. Cumulative incidence of NRM at day +100 and +365 were 23% and 36% respectively; cumulative incidence of relapse at day +365 was 33%. Overall survival and progression-free survival 1 year after HSCT were 51% and 43% respectively. EBV reactivation occurred in 7 patients, but no PTLD was observed. Conclusions The new conditioning regimen we investigated proved to be feasible in this high-risk population. We did not observe any major difference in terms of NRM and aGvHD compared to the data from our previous trial (TrRaMM, Eudract 2007-5477-54) with similar inclusion criteria and patient characteristics, but a reduced-intensity conditioning regimen based on Treosulfan and Fludarabine. Interestingly, we observed a trend of lower relapse incidence, resulting in a better OS and PFS. The low toxicity profile of Treosulfan and Fludarabine should be considered as a myeloablative platform for further intensification; more studies are warranted in order to find the association for a conditioning regimen endowed with a low toxicity profile but still a strong anti-tumor activity. Disclosures: Bonini: MolMed SpA: Consultancy.

Background We previously reported (Styczynski et al, Blood, 2012) that hematopoietic stem cells (HSC) collection from bone marrow (BM) or peripheral blood (PB) in pediatric sibling donors is safe, however there is a risk of mild, short-term early side effects. No data are available so far on follow-up in children donating HSC. Objective To analyze donor safety and side effects related to HSC collection from BM or PB in pediatric sibling donors after 1-year. Donors 171 children: 90 male (M), 81 female (F), median age 9.2 (range: 0.7-17.3) yrs, including 45 children’s weight 40 kg; 31 donors were 8 yrs. There were 25 PB donors 9 (PBD) (18 M, 7 F; median age 11.0, range: 1.3-17.3 yrs ) and 146 BM donors (BMD) (72 M, 74 F; median age 8.3, range: 0.7-17.3 yrs). Methods Data from 14 participating EBMT Centers were registered on specific forms, sent to the PDWP office and statistically analyzed. Results During follow-up local pain was reported by 16/161 (9.9%) donors at catheter site (n=1) or collection site in 16 (14/137 BM; 2/24 PB, ns). 14 (8.1%) donors complained for pain persistence for 1-6 months (1mo-5, 2mo-5, 3mo-2, 5mo-1, 6mo-1). Late vomiting was observed in 7/163 (4.3%) (BMD only), and hematuria in 1 donor. Fever episodes were observed in 21/164 (12.8%) (21/140 BMD, p=0.045), lower respiratory tract infection in 3/164 (1.8%) (1/140 BMD, 2/25 PBD, p=0.056), upper respiratory tract infection in 21/171 (12.3%) (21/146 BM, p=0.046) and urinary tract infection in 5/171 (2.9%) (5/146 BMD, ns). No other infections (including gastroenterocolitis or hepatitis) were reported. Anemia was diagnosed in 6/164 (3.6%) (6/140 BMD, ns). At 1 year follow-up iron was supplemented in 24/164 (14.6%) (22/140 BMD, 2/24 PBD, ns) and folinic acid in 2/163 (1.2%) (BMD only). No other hematological problems (including thrombotic events) were reported. One donor was diagnosed for chronic disease (0.6%) (asthma), 4 (2.4%) had another hospital stay: physiotherapy (n=1), circumcision (n=1), plastic surgery due to an accident (n=1), and donation for MSC (n=1). Assessment of profile of psychological status consisted of a six item questionnaire. At 1-year follow-up, donors felt helpful in 132/154 (85.7%) cases (BMD 109/130, PBD 23/24, ns); happy in 117/149 (78.5%) cases (BMD 93/125, PBD 24/24, p=0.011); proud in 113/147 (76.8%) cases (BMD 91/124, PBD 22/23, p=0.039); depressed in 11/147 (7.5%) cases (BMD 11/124, PBD 0/23, ns) and responsible for recipient in 97/145 (66.9%) cases (BMD 83/122, PBD 14/23, ns). Willingness for subsequent HSC donation was reported by 113/147 (76.8%) children (BMD 94/125, PBD 19/22, ns). Conclusions At one-year follow-up after BM or PB HSC collection in pediatric sibling donors no major side effects were reported, however there is a risk of mild side effects. A donor registry should document and evaluate the course of minors who donate hematopoietic stem cells to better define possible risk factors of BM or PBSC harvest. Disclosures: Dreger: Riemser Pharma : Consultancy, Honoraria, Research Funding.

Background Human herpesvirus type 6 (HHV-6) is a member of the beta herpesvirus subfamily (genus Roseolovirus) and two distinct variants have been described: types A and B. HHV-6 infection is recognized as the cause of a febrile disease and exanthem subitum in early childhood. The infection rarely causes serious events in healthy individuals, but viral reactivation in immunocompromised patients is frequently associated with severe clinical manifestations. Above all HHV-6 is increasingly recognized as an opportunistic and potentially life-threatening pathogen in recipients of allogeneic hematopoietic stem cell transplantation (AlloSCT). Approximately 60% of solid organ transplant and 40% of patients undergoing alloSCT experience HHV-6 reactivation, mainly of variant B. Reported clinical manifestations of HHV-6 infection in transplanted patients are skin rash, interstitial pneumonia, bone marrow suppression and encephalitis. Moreover, some clinical reports suggest that HHV-6 can facilitate the occurrence of severe clinical complications of alloSCT, increasing transplant-related mortality. Methods From January 2009 to February 2013, we retrospectively evaluated 54 consecutive adult patients (median age 50 years) who developed positivity to HHV-6 after alloSCT for high-risk hematological malignancies. Stem cell donors were family haploidentical (37), HLA identical sibling (8), unrelated volunteer (6), cord blood (3). The viral load was determined by quantitative PCR (Nanogen Advanced Diagnostic S.r.L) in cell-free body fluids such as plasma, bronchoalveolar lavage (BAL), cerebrospinal fluid (CSF), bone marrow (BM) aspirates or in gastrointestinal biopsies. Results Median time from alloSCT to HHV-6 reactivation was 34 days (range: 0-705). Thirty-one patients presented HHV-6 positive in plasma, 9/54 in BM, 33/54 in gut biopsies or BAL, 7/54 in CSF. At the time of viral positivity all pts were receiving acyclovir as viral prophylaxis except five. Twenty-nine patients had acute graft versus host disease (GvHD). Twenty-two out of these twenty-nine patients experienced a grade III-IV acute GvHD, requiring high dose steroids in twenty-six cases. A concomitant CMV positivity was detected in 15/54 patients. The median absolute count of CD3+ lymphocytes was 262 cells/mcl. In 52/54 cases we reported HHV-6 clinical manifestations: fever (43), skin rash (22), hepatitis (19), diarrhoea (24), encephalitis (10), BM suppression (18), delayed engraftment (11). HHV-6 positivity led to antiviral pharmacological treatment in 37/54 cases, using as first choice therapy foscarnet. Amongst the total fifty-four patients with documented HHV-6 positivity thirty-one solved the clinical event. However the mortality rate was relatively high in this population (only 30% of patients were alive), mainly related to severe infections or GvHD. A better overall survival is significantly associated with CD3+ cells higher than 200/mcl (p-value 0.011) and time after alloSCT more than 2 months (p-value 0.035). In this analysis the overall survival was not significantly influenced by steroids administration, presence of acute GvHD, plasma viral load and organ involvement. Conclusions This retrospective study further demonstrates the correlation between HHV-6 reactivation and high morbidity and mortality rates in patients after alloSCT. Despite HHV-6 detection typically occurred in the first month after AlloSCT, a better immune reconstitution has the potential to improve the outcome. The regular monitoring of HHV-6 DNA, using a real-time PCR assay, may be useful for identifying active HHV-6 infection and for the introduction of a pre-emptive treatment, possibly reducing the incidence of the most severe clinical complications. Disclosures: Bonini: MolMed SpA: Consultancy.

Introduction Allogeneic Hematopoietic Stem Cell Transplantation (HSCT) represents the best curative option for many patients with high-risk myeloid malignancies, mainly due to its potent immuno-mediated antileukemic effect. Still, post-transplantation relapse remains an unsolved issue. We and others described genomic loss of the mismatched HLA haplotype as a mechanism by which leukemic cells evade donor T cell-mediated immune pressure and cause clinical relapse after partially HLA-incompatible HSCT (Vago et al, N Engl JMed, 2009), but the actual incidence and risk factors of this phenomenon are to date largely unknown. Methods We analyzed retrospectively 224 consecutive partially HLA-mismatched HSCTs performed in our Institute in the last ten years (Unrelated Donor, UD: 60; Mismatched Related Donor, MMRD: 164) in patients affected by myeloid malignancies (Acute Myeloid Leukemia, AML: 173; Myelodisplastic Syndrome, MDS: 27, Myeloproliferative Neoplasms: 17; others: 7). All patients received myeloablative conditioning and infusion of donor T cells, either as part of the graft or as an add-back. Patients’ follow-up included bone marrow genomic HLA typing to identify HLA loss relapses. In selected cases of HLA loss relapse cryopreserved serial serum samples harvested after HSCT were analyzed for the eventual presence of anti HLA Class I or Class II antibodies. Results We documented 77 cases of relapse: 66 after MMRD and 11 after UD HSCT. Out of 77 relapses 21 (27%) were due to genomic loss of the mismatched HLA in leukemic cells. HLA loss occurred in 19 patients with AML, one with MDS and one with myelofibrosis. All the 21 cases of HLA loss occurred after MMRD HSCT (32%), so the analysis for putative risk factors were limited to this subgroup of transplants (n=164), comparing the frequencies of putative risk factors between patients with HLA loss and “classical” relapses (n=21 and 45, respectively). HLA loss relapses occurred significantly later than their classical counterparts (median time to relapse 307 vs 86 days, p Conclusions Genomic loss of the mismatched HLA haplotype is an extremely frequent mechanism of leukemia immune evasion and relapse after MMRD HSCT. It appears to be prompted by selective immune pressure mediated by donor-derived T cells, and accordingly occurs more frequently upon T cell-repleted transplants and in the presence of acute and chronic GvHD, clinical hallmarks of T cell alloreactivity. Conversely the role of NK and B cells in HLA loss needs further investigation, but appears to date less pronounced. Given the poor outcome of re-transplantation, mainly due to toxicity, novel diagnostic and therapeutic approaches are needed to anticipate the detection and improve the treatment of these frequent variants of leukemia relapse. Disclosures: Bordignon: MolMed SpA: Employment. Bonini:MolMed SpA: Consultancy.

Introduction The only curative therapy for thalassemia remains the replacement of the defective erythropoiesis by allogeneic hematopoietic stem cell transplantation (HSCT). Although largely successful, HSCT can have serious adverse effects such as; veno-occlusive disease (VOD), graft failure and graft versus host disease (GVHD) associated mainly with the conditioning regimen. Most commonly used conditioning regimens in children comprise the alkylating agent busulfan (BU). Interindividual differences in Bu pharmacokinetics (PK) have been observed and may be an important cause of resistance to treatment and toxicity. It has been hypothesized that some of this variability in treatment might be predicted by genetic variants of enzymes involved in the metabolism of BU. Identifying pharmacogenetic determinants of BU may allow for prospective identification of patients with suboptimal drug responses allowing for complementation of traditional treatment protocols by genotype-based BU dose adjustment. Since BU is mainly metabolized by glutathione S-transferase (GST), we studied the relationship between functional variants within GSTA1, GSTM1 and first dose pharmacokinetics (PK) and outcomes of intravenous (IV) busulfan (Bu). Methods The study was performed on 44 thalassemia (thalassemia major = 35 and thalassemia intermediate = 9) pediatric patients (median age = 8, Female = 47.7%) of Middle Eastern origin, who underwent allogeneic HSCT with IV BU as part of a myeloablative-conditioning regimen. According to the standard, 5 different IV Bu doses were given based on weight: 1.0mg/kg for 34 kg. Bu was administered as a 2-hour IV infusion every 6 hours for a total of 16 doses from day -9 to day -6. Bu levels following the first Bu dose were measured using an established analytical method and the PK parameters were estimated using non-compartmental analysis. Bu dose levels were adjusted at dose 4 to achieve Bu Css of 600-900 ng/mL. Genomic DNA collected prior to myeloablation was used for genotyping GSTM1 del by gel electrophoresis and GSTA1promoter variants (-69C>T, -513T>C, -631T>G and -1142) by allele-specific oligonucleotide hybridization. Statistical analysis was performed by using Linear regression to test gene-dosage effect and to assess the effect on genotype on (maximum concentration (Cmax), area under the curve (AUC), Css and Clearance (CL) in a univariate model. The cumulative incidence of aGVHD in relation to GST genotypes was estimated by one-survival curves using Kaplan-Meier analysis and log-rank test. Univariate Cox regression analysis was used to estimate hazard ratio (HR) with 95% confidence interval (CI). Results Neutrophil, platelet recoveries, grade 1-4 acute GVHD, grade 2-4 acute GVHD and VOD incidences were 93.2%, 88.6%, 34.1%, 11.4% and 2% respectively. Overall survival rate was 90.9%, events free survival was 84%, while 13.6% of patients had primary and secondary graft failure. Gene-dosage effect between GSTA1 T-69 and G-1142 alleles (defining haplotypes *B and *B1, respectively) and higher Bu exposure (higher Bu levels, p≤ 0.001 and lower clearance, p=0.001) was seen. An association was also seen with GSTM1, where patients with GSTM1 null genotype had a higher occurrence of GVHD grade 1-4 (p=0.01), see Figure 1. Discussion/Conclusion A strong association between GSTA1*B and BU PK was observed in accordance with the functionality of this variant and our previous analysis in a different patient cohort. We were unable to test whether this variant increases BU related-VOD due to the low VOD cases. GSTA1 and GSTM1 variants could potentially open the possibility to tailor first Bu dose according to patient genetics. Disclosures: No relevant conflicts of interest to declare.

Successful gene therapy of inherited blood diseases relies on transplantation and engraftment of autologous genetically engineered hematopoietic stem/progenitor cells (HSPCs) in myeloablated patients. Hematopoietic reconstitution and clinical benefit are related to cell dose, although single disease features might play a role favoring selection of relevant progenitor populations. Gene therapy trials in young pediatric patients are performed isolating CD34+ cells from bone marrow (BM), while in adults mobilized peripheral blood stem cells (PBSC) should represent the favorite target. In the context of gene therapy for thalassemia, the choice of HSPC source is crucial since intrinsic characteristics of patients (splenomegaly and thrombophilia) dictate caution in the use of G-CSF as mobilization agent and prompt investigation of new agents. Moreover, adult thalassemic patients may possibly have a decreased BM stem cell reservoir, due to the BM suppression in response to multiple transfusions. A phase II clinical protocol exploring the use of Plerixafor as a single mobilizing agent in adult patients affected by transfusion dependent beta-thalassemia (EudraCT 2011-000973-30) started in 2012 at our hospital. Plerixafor selectively and reversibly antagonizes the binding of SDF-1 to its receptor CXCR4 with subsequent egress of HSCs to the peripheral blood. The availability of a new source of HSPCs, potentially superior in terms of CD34+ cell yield, transduction efficiency and biological features to steady-state BM, would have a significant impact on the feasibility and efficacy of gene therapy. Four subjects were enrolled and treated by subcutaneously administration of Plerixafor at the single dose of 0.24 mg/kg followed by leukoapheresis. Mobilization of CD34+ cells occurred very rapidly with a peak between 7 to 9 hrs. Three out of four patients achieved the minimal target cell dose (2 x 106 cells/kg) and no severe adverse event occurred. To the aim of engineering Plerixafor-mobilized CD34+ cells for gene therapy, we performed a comprehensive characterization of their biological, molecular and functional properties. In vivo reconstitution potential and lympho-myeloid differentiation were tested following transplantation in NSG mice and compared to those of PBSCs mobilized by G-CSF. Percentages of engrafted human cells in NSG mice transplanted with Plerixafor -PBSCs were about 2- to 5-fold higher than those found in mice transplanted with G-CSF PBSCs. On the same line, the SRC frequency, obtained by pooled engraftment data, was significantly higher (1 SRC out of 47.875 CD34+ cells vs.1 SRC out of 141.203 CD34+ cells). The phenotypic analysis of the frequency of primitive hematopoietic sub-populations revealed that Plerixafor mobilizes preferentially HSPCs and LT-HSPCs, with a percentage of CD34+ CD38-/low CD90+ CD45RA- CD49f+ cells higher than that found in G-CSF PBSCs. This result mirrors the enhanced number of SRCs found in the CD34+ cell population mobilized by Plerixafor. In order to further define the molecular features of HSPCs from different sources, we are studying signalling networks in response to specific cytokines by phospho-proteins analysis and gene expression by microarrays analysis. Our studies are focused on self-renewal, homing, engraftment and multilineage differentiation processes and bioinformatic analysis will reveal the molecular machinery underlying 'stemness' properties of Plerixafor mobilized cells. Disclosures: No relevant conflicts of interest to declare.

Haploidentical hematopoietic stem cell transplantation (HSCT) with T–replete grafts and post-transplant cyclophosphamide (PT-Cy) has gained much interest in the transplantation community for the low rates of GvHD, non-relapse mortality and opportunistic infections. This platform, devoid of anti-thymocyte globulins, allows a thorough analysis of circulating cells in the early phase post-HSCT. Indeed, several biological events that play a critical role for transplant outcome occur within the first month after HSCT; while engraftment and hematological reconstitution are carefully monitored, the shape of T cell dynamics within this timeframe remains largely unknown. We characterized immune reconstitution (IR) during the first month post HSCT in 18 high-risk leukemia patients receiving myeloablative conditioning, T-replete haploidentical peripheral blood stem cell graft (PBSCs), and GvHD prophylaxis consisting of PT-Cy (day 3, 4), followed by mycophenolate mofetil and sirolimus from day 5. Infused PBSCs and blood samples harvested at day 1, 3, 5, 8, 15 and 30 post HSCT were analyzed by multiparametric flow cytometry. T cells were infused in the absence of immunosuppressive agents, and by day 3, prior to PT-Cy, a large fraction of memory lymphocytes, possibly enriched for allo-specificities, proliferated (assessed by Ki-67 staining). Conversely, naïve T cells (TN) were scantly Ki-67+ (P< 0.001). A high CD4:CD8 ratio was observed at this time-point (10). PT-Cy efficiently abated T cell proliferation and appeared to affect CD4 more than CD8 T cells. Nevertheless, T cell numbers progressively increased (mean CD3 counts, day 5: 19 cells/µL; day 8: 27 cells/µL; day 15: 97 cells/µL), suggesting that residual proliferation in extravascular sites was likely to fuel the surge in circulating T cells. Consistently, we observed an expansion of antigen-experienced T cells including central memory (TCM), effector memory (TEM), effectors (TEFF) and the recently described stem memory T cells (TSCM). TSCM are a subset of memory cells hierarchically superior to TCM and TEM, for self-renewal, long-term persistence and functional capacity. Similarly to TN, TSCM coexpress CD45RA and CD62L but differently from TN, TSCM express CD95, a marker of memory cells. As early as day 8 post HSCT, the T cell compartment was predominantly composed by TSCM cells (P < 0.01 compared to all other subsets). Such enrichment in TSCM was not due to a selective resistance to PT-Cy, as suggested by the lack of activity of the ALDH enzyme, which converts Cy to a non-toxic metabolite, in TSCM infused with the graft. Rather, we hypothesized that TSCM expansion came directly from the differentiation of TN infused within the graft, which escaped the purging effect of PT-Cy thanks to a delayed activation kinetics compared to alloreactive memory T cells. We demonstrated the in vivo differentiation of WT1 and PRAME specific TN cells, present in the graft, into memory lymphocytes, comprising TSCM cells, in 4/7 patients suitable for dextramer tracking. Such tumor specific T cells were detected in the peripheral blood and bone marrow of treated patients, suggesting that PT-Cy did not hamper GvL players. Of note in the remaining patients for whom tumor-specific TN were not detectable in the graft, no tumor response could be documented in vivo. From day 15 post HSCT, TSCM were outnumbered by other memory subsets, suggesting their differentiation into more committed TCM TEM and TEFF. The quality of IR correlated with clinical events. The percentage of circulating Ki-67+ CD8 TEMcells at day 8 post HSCT accurately predicted the occurrence of periengraftment syndrome, observed in 4 patients with a median time to onset of 15 days. Acute GvHD (Grade I/II in 6 patients, grade III/IV in 4) was accompanied by a rise in circulating Ki-67+ CD8 cells, and response to therapy resulted in a drop in Ki-67 expression. No immunological parameter correlated with chronic GvHD, observed in 2 patients. In all patients with a CMV-seropositive donor, CMV-specific T cells were tracked in the graft, at early time-points and up to 180 days post HSCT, indicating that virus-specific T cells escaped PT-Cy. These results suggest that PT-Cy acts mainly on alloreactive memory T cells infused within the graft, while sparing infused virus-specific, non cross-reactive, memory cells and TN, which can differentiate predominantly in TSCM, but also in TCM TEM and TEFF, thus promoting a rapid and broad IR. Disclosures: Bonini: MolMed SpA: Consultancy.

Background Hemorrhagic cystitis (HC) is a common cause of morbidity after allogeneic stem cell transplantation (allo-SCT), and symptoms vary from asymptomatic microscopic to frank hematuria with clot formation and urinary tract obstruction. Multiple factors including toxicity of chemo-radiotherapy, BK virus reactivation seems to be involved a in post-transplant HC, nevertheless effective risk factors and treatments of this complication are currently unknown and unresolved. Cidofovir (CDV) is an acyclic nucleoside analogue with a broad range of antiviral activity, including BK virus and thus it has been proposed as treatment for HC after allo-SCT. Methods In this study we retrospectively evaluated 59 consecutive adult patients (median age 45 years) who received CDV for HC after allo-SCT from January 2008 to December 2012 at San Raffaele Hospital. All patients were affected by high risk hematologic malignancies and 39 had active disease at time of transplant. Donors were HLA identical sibling (n=8), family mismatched (n=39), unrelated volunteer (n=11), cord blood (n=1). All patients received a fully myeloablative conditioning regimen, infusion of donor T cells, 25 patients (43%) received also Total Body Irradiation (4 Gray) and in 51 cases (86%) was administered anti-thymocyte globulin as part of the conditioning regimen. BK viral load was determined on urine by TaqMan PCR. CDV was administered at the dose of 5mg/kg/week intravenously (i.v.) in 41 patients and intravescically in 21 patients (4 double treatments). The median dose number of CDV doses was 2 (range 1 to 8). The intravescically route was adopted in case of pending renal insufficiency or impossibility to interrupt intravenous antiviral for concomitant viral reactivations. Results HC occurred in median 14 days after allo-SCT (range -4 to 330). Median duration of symptoms was 34 days (range 6 to 166). At treatment onset 13 patients had grade 0-I HC, 13 grade II, 24 grade III and 9 grade IV. In 55 cases (93%) high BK viral load was detected in urine (BK virus median load 10^7 cp/ml) before treatment. After treatment the reduction of BK viruria was documented in 29 out of 33 evaluable cases (87%), with a 1-log reduction of BK viruria median load (p=0.004). Improvement of HC grade was observed in 41 patients (70%) and a complete clinical response within 7 days from last CDV dose was observed in 30 cases (51%). Worsening of HC leading to urological intervention occurred in 5 treated patients. Four patients died with an ongoing uncontrolled HC: 2 of acute Graft-versus Host Disease, 1 of pneumonia and 1 of relapse. During i.v. CDV treatment 22 out of 41 patients (54%) had a viral reactivation (Cytomegalovirus n=14, Epstein-Barr Virus n=8, Herpes Simplex-1 n=3, Herpes Simplex-6 n=4) and 2 patients developed acute renal failure requiring drug discontinuation. Conclusions CDV treatment after allo-SCT is associated with a reduction of BK viruria load and HC clinical responses in more than half of cases. This is in agreement with data reported in other retrospective trials. Viral reactivations under CDV treatment should be better investigated in the allo-setting, since the long-half life of the drug and its potential nephrotoxicity limits the possibility of concomitant antiviral therapy with other agents. Our data warrant prospective trials to investigate the role of CDV in allo-SCT. Disclosures: Off Label Use: Cidofovir is an acyclic nucleoside analogue with a broad range of antiviral activity, including BK virus and thus it has been proposed as treatment for hemorrhagic cystitis after Allogeneic Stem Cell Transplantation.

Abstract 5504 Backgroud Allogeneic transplantation (HSCT) is the only potentially curative therapy for myelofibrosis, even in the era of new drugs that only impact on selected manifestations of disease. The time to evolution of myelofibrosis in advanced phases is variable (months to several years). The choice to proceed to allogeneic transplantation is based on several clinical variables; conditioning regimen and time to transplantation may influence the outcome of HSCT. Here we present our experience in a group of patients with myelofibrosis transplanted in Our Center with a myeloablative regimen based on full dose of treosulfan. Methods We retrospectively evaluated 20 patients (15 male) with primary myelofibrosis (14) and post-ET (essential thrombocythemia) myelofibrosis (6) who underwent HSCT at our institute from July 2005 to February 2013. In this cohort we included 4 patients in blast phase, 3 of which received a brief course of chemotherapy prior to transplant; 4 patients who underwent a second allogeneic transplantation for disease relapse (2) or graft failure (1); 1 patient referred at our Institute in graft failure 3 months after first HSCT. Only 1 patient had splenectomy before HSCT. Results The median age at diagnosis was 59 years (range 41-76). JAK2 V617F mutation was positive in 7 and unknown in 3 patients. In post-ET MF patients, the median time to transformation in MF was 134 months (60-144). The median time from diagnosis to transplant was 14 months (4-101 months). The median age at transplant was 62 years. DIPSS score at transplant was low in 1, int-1 in 3, int-2 in 13 and high in 3 patients. We adopted myeloablative regimen based on treosulfan 42 gr/ms and fludarabine 150 mg/ms, plus TBI 4 Gy in 7 patients. GvHD prophylaxis was based on ATG, Rituximab and CSA/MTX (8 pts) or rapamycin (11 pts). The graft was PBSCs (19) and BM (1) from related HLA-identical donor (7 pts), matched unrelated donor (5 pts) and haploidentical donor (8 pts). The incidence of graft failure and poor graft function was 5% and 20% respectively. The median time to neutrophils engraftment was 20 days. The incidence of acute and chronic graft versus host disease was 50% and 40% respectively. Cumulative incidence of TRM (transplant related mortality) was 45 %; day 100 OS (overall survival) was 70% while 2 year OS was 40%. In multivariate analysis there was no statistically significant correlation between individual factors (including WBC, hemoglobin, platelets, ferritin, beta2-microglobulin, IgA, IgG, IgM, LDH, psuedocholinesterase levels, age, Sorror comorbidity score, donor match, bone marrow kariotype) and survival. However, we found that a linear composition of level of peripheral blasts (0%, ≥1%, ≥5%), bone marrow CD34+ cells ( Conclusions A myeloablative regimen based on full dose treosulfan provide a 95% rate of primary allogeneic engraftment and 40% overall survival in myelofibrosis at advanced stage, with low extra-hematological toxicity in frail patients. Allogeneic transplantation after myeloablative low-toxicity regimens may be offered in myelofibrosis in early chronic phase of disease and for younger patients, two conditions usually linked with durable engraftment, low toxicities and low rate of relapse. Disclosures: No relevant conflicts of interest to declare.

1920 Background. Understanding of leukemia biology and advances in the transplant field have improved the safety as well as access of allogeneic hematopoietic cell transplantation (HCT) for a larger number of patients (pts) affected by acute myeloid leukemia (AML). The trend of growth of HCTs in adult pts with AML can be expected to continue based on acceptance and availability of alternative donor. Few data are available for: i) the reliable estimates of the number of HCT for AML and the total number of AML pts for whom HCT is appropriate, ii) the choice of the different donor sources. A risk-adapted treatment strategy is crucial to improve the outcome of pts with AML. Our policy is to offer a haploidentical HCT to adult pts lacking a matched donor in the appropriate time according to clinical indications ([www.leukemianet.org][1], [www.ebmt.org][2]). This policy is integrated in ongoing protocols for primary disease ([www.nilg.it][3]). Methods. Here we are reporting the intention-to-treat (ITT) analysis of HCT in all consecutive AML pts referred to our Institution between January 2004 and April 2012. Classification, prognostic evaluation, response criteria and survival outcomes for AML were defined according to the standard recommendation of the European LeukemiaNet (Dohner H et al, Blood. 2010: 115:453–474). Results. Indication to HCT was given to 241 pts (median age 52y, r17-72, 66 pts over-60y; male 138). HCT was performed in 201/241 pts (median time from diagnosis to HCT 222 days, median time from HCT-indication to HCT 80 days), 24/201 pts received a second HCT due to disease relapse. Pts distribution according to ITT algorithm is reported in [figure 1][4]. In ITT analysis, 83,4% of candidate pts received an HCT. Characteristic related to pts/disease/transplant are reported in [table 1][5]. Noteworthy, pts in 1st complete remission (CR1) are evenly distributed according to donor source (namely HLA-matched sibling donor – MSD, unrelated donor – URD, haploidentical related donor - haplo-HCT). The overall survival (OS) analysis for pts transplanted in CR is 71% at 1y and 56% at 3y, for pts in morphologic leukemia free state (MLFS) 32% and 21%, for pts in relapse 23% and 11% (p/2 | 4 (9%) | 12 (29%) | 2 (28%) | 24 (18%) | | - MLFS | 1 (2%) | 3 (7%) | 2 (28%) | 7 (5%) | | - relapse | 14 (31%) | 3 (7%) | 3 (43%) | 74 (57%) | Table 1. Patients, disease and transplant characteristics. ![Figure][7] ![Figure][7] Disclosures: Bordignon: MolMed SpA: Employment. [1]: http://www.leukemianet.org [2]: http://www.ebmt.org [3]: http://www.nilg.it [4]: #F1 [5]: #T1 [6]: #F2 [7]: pending:yes

Abstract 586 Gene therapy of inherited blood diseases requires harvest of hematopoietic stem cells (HSCs) from patients and autologous transplantation of genetically modified cells. In order to achieve correction of the disease, high number of HSCs and previous conditioning of the host bone marrow (BM) are necessary. In the clinical application of gene therapy for thalassemic patients the choice of the HSC source is a crucial issue. On one side, the minimal target dose poses a challenge for the use of steady state BM since reinfusion of high numbers of beta globin gene modified CD34+ cells is probably necessary to gain sufficient correction of the genetic defect in order to achieve transfusion independency; on the other side, the disease related features and complications of thalassemic patients (i.e. splenomegaly and thrombophilia) dictate caution in the use of G-CSF as mobilizing agent. In April 2011 a clinical protocol exploring the use of Plerixafor (AMD3100) as single agent was started (“Plerixafor mobilized stem cells as source for gene therapy of beta-thalassemia”, acronym AMD-THAL, EudraCT2011-000973-30). Aims of the trial were to explore the ability of Plerixafor in inducing safe and effective stem cells mobilization in adult patients affected by beta-thalassemia, to characterize stem/progenitor cells mobilized from the BM and peripheral blood of treated subjects and to achieve gene transfer efficiency of mobilized CD34+ cells at a level comparable to that obtained using steady state BM. Four patients (01, 02, 03 and 04) were enrolled and already mobilized to date (August 2012). All patients are affected by transfusion dependent beta-thalassemia and aged 28 (01), 41 (02), 39 (03), 33 (04). Two are splenectomized (02 and 03); all subjects are regularly iron chelated with adequate organ function. Administration of Plerixafor subcutaneously as single agent and at the single dose of 0.24 mg/kg resulted in mobilization of CD34+ cells/mcl with a peak of 78 cells at 9 hrs (01), 70 cells at 7 hrs (02) and 69 cells at 8 hrs (03); suboptimal mobilization was observed in patient 04 (peak 18 at 8 hrs). Patient 03 received a second dose at 0.40 mg/kg 24 hrs after the first dose and underwent a second leucoapheretic procedure. Harvest by leukoapharesis resulted in procurement of the following CD34+ cells/kg: 1.84 × 106 (01) and 4.43 × 106 (02) with a unique leukoapheretic procedure, and 3.57 × 106 (03) with two leukoapheresis. No apheresis was performed for patient 04 because the minimum target of 20 CD34+ cells/mcl in peripheral blood was not reached. CD34+ cells selection through Clinimacs Miltenyi resulted in the following yield: 1.2 × 106 CD34+ cells/Kg, 65% recovery (01), 2.66 × 106 CD34+ cells/Kg, 60% recovery (02), 1.78 × 106 CD34+ cells/Kg, 50% recovery (03). No severe adverse event occurred. Recorded side effects were: grade 3 hypotension related to the apheretic procedure (01), mild grade 1 facial disestesia (02 and 04) and hyperleukocytosis (02: WBC from 13.6 to 42.6 × 103/mcl). In addition, steady state and Plerixafor primed BM aspirates were performed to analyze any modification in CD34+ concentration in the BM following Plerixafor administration. In fact, Plerixafor administration resulted in enrichment of CD34+ cells concentration in the BM. Purified CD34+ cells from leukoapheresis of the 4 treated patients were analyzed for their biological and functional properties, subpopulations composition and expression profile. In vivo reconstitution potential and lymphomyeloid differentiation of CD34+ cells were tested following transplantation in NSG mice. Experiments are ongoing but preliminary results indicate that cells mobilized by Plerixafor have a primitive phenotype with a high reconstitution potential and are efficiently transduced with a lentiviral based vector, named GLOBE, encoding for the human beta-globin (Roselli et al., 2010), thus being a suitable source of target cells for gene therapy. Disclosures: No relevant conflicts of interest to declare.

Abstract 1957 Background: In spite of the considerable progress achieved during the last decade in the field of allogeneic Hematopoietic Stem Cell Transplantation (HSCT), disease relapse remains a crucial unsolved issue, due to our limited insights into the biology of the interplay between leukemia and donor immunity. We and others have shown that genomic loss of patient-specific mismatched HLA is a frequent mechanism by which residual leukemic cells can evade donor T cell-mediated immune control and determine a clinical relapse. HLA loss relapses have been reported both after family haploidentical and after volunteer unrelated donor HSCT, but the actual incidence and risk factors for these peculiar relapses are to date unknown. Methods: We retrospectively evaluated 230 consecutive transplants performed over the last ten years in a single institution. All donors were partially HLA mismatched (family mismatched: 170; volunteer unrelated: 60). All patients were affected by high-risk myeloid malignancies (Acute Myeloid Leukemia (AML): 179; Myelodysplastic Syndrome (MDS): 27; Myeloproliferative Neoplasms: 17; Others: 7), received a fully myeloablative conditioning regimen, and infusion of donor T cells, either as part of the graft or as post-transplantation add-back. In addition to standard bone marrow morphological examination, post-transplantation follow-up comprised genomic HLA typing of bone marrow aspirate samples, aimed to identify HLA loss relapses. Results: A total of 83 relapses occurred, 72 and 11 after related and unrelated donor HSCT, respectively. We documented 21 relapses with genomic loss of the patient-specific mismatched HLA (25% of relapses). HLA loss occurred predominantly in patients with AML (n=19), but was also observed in patients with MDS (n=1) and primary myelofibrosis (n=1). None of the 11 cases of relapse after volunteer unrelated donor HSCT displayed HLA loss, whereas it was evident in 21 out of 72 (29%) relapses after family mismatched donor HSCT. Accordingly, the presence of multiple (more than 4) HLA mismatches between donor and recipient represented a significant risk factor for HLA loss (HR: 4.17, 95% CI: 0.88–19.82, p=0.07). None of the disease-related factors tested (morphological subtype, presence of dysplasia, hyperleukocytosis, cytogenetic and molecular profile) correlated significantly with HLA loss. In line with the hypothesis that selection of these leukemic variants may be elicited more frequently in the presence of a strong alloreactive immune pressure, HLA loss occurred more frequently in patients with clinical Graft-versu-Host Disease (GvHD), either acute (p=0.02) or chronic (p=0.007). Interestingly, HLA loss relapses occurred later than their “classical” counterparts (median time to relapse 307 vs 116 days, range 56–784 vs 10–579, p Conclusions: Loss of the mismatched HLA is a frequent mechanism of relapse for patients with high-risk myeloid malignancies, and is associated with donor-versus-host alloreactivity, as demonstrated by its significant correlation with the number of donor-recipient HLA mismatches and with the occurrence of GvHD. Ultimately, given the documented ineffectiveness of lymphocyte infusions from the original stem cell donor in patients with HLA loss relapses, efforts should be aimed towards the optimization of early detection tools and targeted therapeutic strategies specific for these peculiar and frequent relapse variants. Disclosures: Bordignon: MolMed SpA: Employment. Bonini:MolMed S.p.A.: Consultancy.

Abstract 4198 Background and Methods. Chronic Graft-versus-Host-Disease (GvHD) remains a serious complication after allogeneic stem cell transplantation. In 2005 the National Institutes of Health (NIH) established new criteria for chronic GvHD based on retrospective data and expert recommendations. Here we are reporting the prospectively evaluation of the incidence of NIH-defined chronic GvHD and its prognostic impact in 113 consecutive patients who underwent unmanipulated peripheral blood graft from an HLA-haploidentical relative after a treosulfan based conditioning at our Institution. The peculiarity of this setting relies on the exploitation of a rapamycin-based, calcineurin-inhibitor-free regimen for prophylaxis of GvHD to induce in-vivo expansion of T-regulatory cells (Tregs). Results. Chronic GvHD was evaluable in 81 patients: 41 patients were diagnosed with chronic GvHD according to the revised Seattle criteria, 28 were classified as having extensive chronic GvHD and 13 were classified as having limited. The 1-year cumulative incidence was 43 +/− 9%. According to the NIH Consensus Criteria, 1 patient was reclassified as having late-acute GvHD, 20 patients as having overlap syndrome and 20 patients as having classic chronic GvHD. The late-acute consisted of late onset subtype. The 40 patients with classic chronic GvHD and overlap syndrome were graded as moderate (26 patients) and severe (14 patients) by NIH consensus criteria. The onset was classified as progressive in 4 cases, de novo in 27 cases, quiescent in 9 cases. The median number of organs involved was 3 (range 1–7), the majority of patients presented with skin and oral involvement, but also eyes, liver, joint, genitalia and gastro-intestinal damages were present – maximum severity of chronic GvHD according to organ manifestation is presented in figure 1. Twenty-seven out of 40 patients started a specific immunosuppressive treatment for chronic GvHD, noteworthy 21 patients restarted rapamycin (in combination with prednisone, or alone) with clinical benefit. In univariable analysis patients with overlap GvHD tended to present a lower overall survival (OS) compared to those with classic chronic GvHD (36% versus 63%, p 0.07). Patients with severe chronic GvHD at onset had a significantly lower OS compared to those with moderate chronic GvHD (19% versus 69%, p0.017). OS was significantly worse for patients with platelets counts below 100 g/l at onset of chronic GvHD (29% vs 67%, p0.003)– figure 2. Conclusion. This analysis confirms in haploidentical setting thrombocytopenia, overlap category and severe presentation as prognostic items for overall survival after allogeneic stem cell transplantation. Further investigations on implementation of immunosuppressive treatment strategy for high-risk GvHD patients (namely patients with overlap GvHD diagnosis and concomitant thrombocytopenia and/or progressive onset) are actually ongoing to enhance response and improve outcome. Disclosures: Bordignon: MolMed SpA: Employment. Bonini:MolMed S.p.A.: Consultancy.

Background The aim of this study was to perform a longitudinal assessment using Quantitative Muscle Testing (QMT) in a cohort of ambulant boys affected by Duchenne muscular dystrophy (DMD) and to correlate the results of QMT with functional measures. This study is to date the most thorough long-term evaluation of QMT in a cohort of DMD patients correlated with other measures, such as the North Star Ambulatory Assessment (NSAA) or thee 6-min walk test (6MWT). Methods This is a single centre, prospective, non-randomised, study assessing QMT using the Kin Com® 125 machine in a study cohort of 28 ambulant DMD boys, aged 5 to 12 years. This cohort was assessed longitudinally over a 12 months period of time with 3 monthly assessments for QMT and with assessment of functional abilities, using the NSAA and the 6MWT at baseline and at 12 months only. QMT was also used in a control group of 13 healthy age-matched boys examined at baseline and at 12 months. Results There was an increase in QMT over 12 months in boys below the age of 7.5 years while in boys above the age of 7.5 years, QMT showed a significant decrease. All the average one-year changes were significantly different than those experienced by healthy controls. We also found a good correlation between quantitative tests and the other measures that was more obvious in the stronger children. Conclusion Our longitudinal data using QMT in a cohort of DMD patients suggest that this could be used as an additional tool to monitor changes, providing additional information on segmental strength.

Abstract 4463 Background: The prognosis of patients with acute leukemia (AL) relapsed after allogeneic stem cell transplantation (allo-SCT) is namely poor. The management relies on implementation of the Graf versus Leukemia (GvL) effect either by immunosuppression withdrawal or administration of Donor Lymphocyte Infusions (DLI); these measures are particularly effective if tumor burden is limited. In case of higher tumor burden, instead, other strategies can be exploited, such as cytoreductive chemotherapy (CT) and/or further allo-SCT with a different conditioning regimen or the use of a more mismatched donor. Aim: Analysis of variables associated with outcome and response to different salvage strategies in pts with AL relapsed after allo-SCT. Materials and methods: we performed a retrospective analysis of a cohort of 64 consecutive pts with AL transplanted at the San Raffaele Scientific Institute and relapsed during follow up. Chi-square analysis was used for the association between variables; Kaplan Meyer curves and Long-rank test were used for survival analyses. Results: Between 09/2003 and 10/2010, 64 pts relapsed after receiving allo-SCT (median time to relapse: 6 months, range: 1–38); 54/64 pts (84%) had overt hematological relapse, 10/64 pts (16%) MRD positivity and/or Mixed Chimerism (MC). Therapeutic options applied were DLI or second allo-SCT, preceded or not by reinduction CT. Ten pts with MRD positivity and/or MC received DLI as first choice strategy. Among them, 4 had a sustained CR (40%) and 6 progressed to overt relapse; in 5 cases an allo-SCT was performed, and 1 pt was rescued. Fifty-four pts presented with overt relapse: 14 received DLI as first line salvage therapy; 2/14 (14%) obtained durable CR; an allo-SCT was attempted in 5/12 pts who progressed, with success in one. Fourteen pts went directly to a further allo-SCT; among them, 1 (7%) obtained durable CR. The remaining 26 pts received allo-SCT after re-induction CT; 5 (19%) obtained sustained CR. A further allo-SCT, given as first-choice strategy or used as a rescue treatment after DLI failure, was followed by a longer OS compared to DLI only (median OS 328 vs. 187 days after relapse, p=0.03). Survival, in particular, was longer in pts receiving DLI or CT as “debulking” strategy before undergoing further allo-SCT (DLI only v.s. SCT only vs. SCT + debulking: Median OS 187 vs. 159 vs. 351 days after relapse, p=0.07). Of note, all the long-surviving patients changed donor for the second SCT (alive 31% vs. 0% p=0.02) Taken together, 24 pts were given DLI as fist choice strategy, and received a median of 2 DLI infusions (range 1–4), with a median dose of 1×10^6 CD3/Kg (range: 1×10^5–1×10^8 CD3/Kg); 5/24 pts (21%) developed acute GvHD (max grade III in a single case). In univariate analysis, variables with a tendency to be associated with response to DLI were: early disease at transplant (p=0.07), Reduced Intensity Conditioning (p=0.06) and the use of Rapamycin for the GvHD prophylaxis (p=0.1). Variables with a tendency to association of longer OS after DLI were MRD positivity and/or MC (p=0.01), response to first DLI (p=0.07) and time to relapse longer than 6 months (p=0.1). DLI doses associated with the best response (50%) were 1×10^7 CD3/Kg for MRD and MUD and 1×10^6 CD3/Kg for MMRD respectively. Of note, no association was observed between DLI doses and incidence of GVHD. Conclusions: DLI is a reasonable option to treat pts with MRD positivity or MC after allo-SCT. When CR is not achieved after the first DLI, anyway, the switch to a more aggressive approach such as a further allo-SCT should be considered. The association of DLI with low-dose CT or other immune-modulating agent should be further exploited. For pts in over relapse, a further allo-SCT, if feasible, offers the best opportunity of prolonging survival. A debulking strategy such as CT or DLI should be considered according to the characteristics of the pts and the disease. Disclosures: Bonini: MolMed: Consultancy.

Abstract 4471 Allogeneic stem cell transplantation (HSCT) is an emerging risk factor for cardiovascular disease. Long-term survivors seem to be at higher risk for premature arterial vascular disease compared with sex- and age-matched population. In HSCT, pre-transplant treatments and the conditioning regimen play a key role in endothelial and organ damage. The use of immunosuppressant drugs to prevent graft-versus-host disease (GvHD) influences as well the development of cardiac disease. To better understand the impact of treosulfan-based conditioning regimens in leading to the emergence of cardiovascular disease, we retrospectively evaluated 94 consecutive patients who had survived longer than 1 year, transplanted at Our Institution between 2002 and 2010 (62 males – median age 46, range 14–69). For 48 patients an HLA-identical sibling was available, 6 patients found an unrelated donor while 40 patients underwent haploidentical HSCT from family donors. Forty-six patients received in vivo T-cell depletion and 72 B-cell depletion. GvHD prophylaxis was based upon cyclosporine + methotrexate for the HLA-identical transplants (48 – median EBMT risk score 3) whereas rapamycin + MMF were used for patients undergoing transplantation from HLA-haploidentical donors (35 – median EBMT risk score 4); 9 did not receive any immunosuppression because of application of suicide gene strategy as tool to prevent GvHD (median EBMT risk score 3). We compared clinical variables (i.e. GvHD, OS, TRM, major cardiac events and comorbidities) with biochemical and functional tests (i.e. cardiac function, lipid profile and ferritin levels) both before and 1 year after transplantation. After a median follow-up of 29 months, only 3 patients experienced a major cardiovascular event; no one experienced a late congestive heart failure. In all series, we found that ferritin levels significantly decrease after 1 year of follow-up, compared to pre-transplant values (P Disclosures: No relevant conflicts of interest to declare.

Abstract 4921 BACKGROUND: Febrile neutropenia and sepsis are frequent and life-threatening complications in patients with hematological malignancies. Prompt administration of appropriate antimicrobials is crucial to decrease the high morbidity and mortality rates of these conditions. Blood cultures (BC) identify a pathogen in only 20 to 30% of febrile episodes, with even lower sensitivity in patients already receiving antibiotics at time of sampling. Moreover the culturing and pathogen identification process is lengthy, postponing the start of a pathogen-targeted treatment, a particularly relevant issue when highly aggressive or rare agents are involved. Thereby the setup of molecular tools able to promptly recognize pathogens causing sepsis even despite ongoing antimicrobial therapy is of potential clinical relevance. METHODS: We assessed the diagnostic usefulness of the LightCycler SeptiFast test (SF), a PCR-based multiplex assay which can be performed on peripheral blood in hematological patients. In this study, blood samples from febrile oncohaematological patients were tested by traditional blood culture (BacT/Alert 3D; bioMerieux) and by a novel commercial real-time PCR assay (LightCycler SeptiFast; Roche Molecular Systems) performed concomitantly at the onset of febrile neutropenia. RESULTS: A total of 869 blood samples were collected from 273 consecutive patients treated for febrile neutropenia at the San Raffaele Hematology Unit over the last three years (July 2009–July 2011). Out of the total 869 episodes examined, positive results were detected in 246 samples by SF (28.3%), and in 143 by BC (16.4%). Together, the two methods identified a total of 345 microorganisms in 312 (36%) episodes: Gram-positive bacterial species (74%), Gram-negative bacterial species (23%), and fungal species (3%). Concordance between the two methods was 73%, mainly due to samples that tested negative by culture but positive using the molecular approach (54% of the total positive samples). The cases positive by SF alone were mostly samples from patients with initial concordant results on samples harvested before the administration of a specific antimicrobial therapy, or, importantly, sample positive for a clinically relevant agent such as Aspergillus fumigatus, which is hard to detect by the traditional approaches. CONCLUSION: The LightCycler SeptiFast test gives new insights into the natural history of infection and in the development of new algorithms for the diagnosis of sepsis in critical patients. Using SF combined with BC improves microbiological documentation in febrile neutropenia particularly in persistent fever despite antibacterial therapy, when a nonresponding bacterial infection or an invasive fungal infection is suspected; results of SF may lead to a more targeted antibiotic therapy early after the onset of fever. Disclosures: No relevant conflicts of interest to declare.

Abstract 2385 Background. Allogeneic haemopoietic stem cell transplantation (HSCT) is the best therapeutic option for high-risk hematological disease (HRHD), particularly acute myeloid and lymphoblastic leukemia (AML/ALL). A widely application of HSCT is limited by lack of availability of a suitable donor for every candidate patients (pts). In order to offer a donor to every candidate pts, several centers had developed in the last decade alternative strategy of HSCT, such as umbilical cord blood (UCB) or family haploidentical HSCT (haplo-HSCT). With the aim to treat high-risk leukemia in the ideal appropriate time by allogeneic HSCT, we adopted a policy relying upon HLA typing at entry of every pts diagnosed with HRHD, followed, in absence of a MRD, by the prompt activation of the MUD search. Patients lacking a MRD or a MUD at the appropriate timing are proposed for haplo-HSCT. Methods. Here we report an intention-to-treat analysis of alternative donor HSCT at our Institution for pts diagnosed with high risk AML or ALL. Data were obtained from local institutional database. Results. Between Jan-2004 and July-2010 241 pts (median age 48y, r 15–72) with diagnosis of ALL (60 pts; median age 33y, r 15–64; male 39) or AML (181 pts, median age 51y, r 19–72; male 83) were defined as “high risk status” and received an indication to HSCT according to EBMT (European Group for Blood and Marrow Transplantation) and Northern Italy Leukemia Group (NILG, www.nilg.it) recommendations. In the ALL group 3 pts died before proceed to HSCT, 5 pts are waiting for the identification of a donor. Overall, 52/60 (86%) pts underwent HSCT, the status of disease at transplant was of complete remission (CR) for 27 pts, persistence of disease (PD) for 25. In the AML group 6 pts died before proceed to HSCT, 15 pts are waiting for the identification of a donor. Overall, 160/181 (88%) pts underwent HSCT, the status of disease at transplant was of CR for 97 pts, PD 63. Overall 92 pts activated the research of a MUD, 42 proceed to transplant, 7 received a UCB, 26 received a haplo-HSCT due to absence of a suitable donor in the appropriate time frame or failure to met the criteria to engage a MUD donor. The median time from diagnosis to registry activation was 69 days (r 5–876), the median time from activation to transplant 84 days (r 28–348). In the group of pts in CR at transplant, 37 underwent HSCT from a MRD and 36 from a MUD, 4 pts received a UCB and 47 a haplo-HSCT. Seventy-two pts are alive and in CR at last follow-up, 3/72 after a second transplant from a different donor (haplo-HSCT) and 3/72 after chemotherapy and adoptive immunotherapy to treat hematological relapse. Fifty-two pts died and the causes of death were: relapse (27), infection-related (19), graft-versus-host-disease (GvHD; 5), acute myocardial infarction (1). In the group of pts in PD at transplant, 16 underwent HSCT from a MRD and 6 from a MUD, 3 pts received UCB and 63 a haplo-HSCT. Fifteen pts are alive, 14 in CR, 1 pts under adoptive immunotherapy; 1/14 pts received a second transplant from a different donor (haplo-HSCT) to treat hematological relapse. Seventy-three pts died and the causes of death were: relapse (43), infection (23), GvHD (7). Overall, the median survival is 382 days and the median follow-up for pts alive is 548 days. The 1-year overall survival (OS)/transplant related mortality (TRM)/relapse incidence (RI) are 50,76% 26,96% and 40% respectively. For pts transplanted in CR the 1y OS/TRM/RI are 77,2%, 20,01% and 25% respectively. The outcome analysis per donor source (MRD vs MUD vs haplo-HSCT) is comparable (p=ns). For pts transplanted in PD the 1y OS/TRM/RI are 19,7%, 41% and 67% respectively. The outcome analysis per donor source (MRD vs MUD vs haplo-HSCT) shows a trend of lower RI and TRM in the haplo-SCT vs MRD. Conclusion. The policy adopted provided an allogeneic HSCT in > 80% of candidate high-risk acute leukemia patients. No significant differences were registered in outcome for patients transplanted from matched-related, unrelated or family haploidentical donors. Further evaluation and a long-term follow-up will add important evaluation in term of long-term disease control and long-term toxicities. Disclosures: Bonini: MolMed: Consultancy. Bordignon: Molmed: Employment.

Abstract 2382 Background. Allogeneic transplantation of haemopoietic stem cells (allo-SCT) from an HLA- matched related (MRD) or unrelated donor (MUD) is a curative option for patients (pts) with high-risk haematological disease (HRHD). In the absence of a MRD or MUD, pts have been offered investigational transplant strategies such as umbilical cord blood (UCB) or family haploidentical SCT (haplo-SCT). In our Institution, all patients with HRHD are typed at entry; if a suitable MRD donor is missing a MUD search is promptly activated through the Bone Marrow Donors Worldwide Registry (BMDW). Our policy is to offer an haplo-SCT to adult pts lacking an MRD or MUD in order to adequately treat HRHD in the ideal appropriate time according to clinical indications for allo-SCT. This policy is based on our ongoing protocols for primary disease. Methods. Here we report the intention-to-treat (ITT) analysis of alternative donor transplantation at our Institution. Data were obtained from Institutional database; all HRHD patients were included in analysis. Results. Between Jan-2004 and July-2010, 410 pts (100% of the following ITT analysis; median age 48y, range 15–76, 91 pts over-60y; male 264) received indication to allo-SCT according to EBMT recommendations. The majority of pts presented with a diagnosis of acute leukaemia (15% lymphoblastic, 45% myeloid), while 12% presented with non Hodgkin lymphoma, 8% myelodysplastic syndrome, 6% Hodgkin disease, 5% multiple myeloma, 2% chronic myeloid leukaemia, 2% chronic lymphocytic leukaemia, 2% severe aplastic anaemia, 1% primary myelofibrosis, 2% others. Eighty-nine pts (22%) received a transplant from a MRD; 190 pts (46%) activated an MUD search in the BMDW registry; 84 pts (20% of total pts, 44% of MUD searching) received a MUD transplant; 42 pts (10%-21%) received an haplo-SCT due to lacking of a suitable MUD in the appropriate timing according to disease status, or absence of suitable criteria to engage a MUD donor; 11 pts (3%-6%) received a UCB if lacking a suitable haplo donor. Overall, 149 pts received an haplo-SCT (36%): 42 after BMDW research, 107 up-front. Twenty-one pts died before receiving a transplant (5%), 37 (9%) are still searching for a suitable donor and an eligible donor is under final evaluation for 19 pts (5%). One-hundred-fifty pts underwent transplant in complete remission (CR), 12 in early phase, 9 in very-good-partial remission (VGPR), 7 in partial response (PR), while 155 were in progression of disease (PD). The median time from diagnosis to transplant was 165 days, the median time from MUD search to transplant 103 days (range 28–824 days). The overall survival (OS) analysis in intention to treat is 51% at 1 year, 39% at 3y; the 1y and the 3y OS for pts transplanted in CR/early phase/VGPR are 74% and 57% respectively, for the pts transplanted in PR/PD 29% and 21% (p At last evaluation 149 pts are alive, with a median follow-up of 802,5 days (range 2–2315); 93/149 received transplant in CR, 10 in early phase, 6 in VGPR, 3 in PR, 37 in PD. Twenty out of 149 experienced disease relapse and were rescue with salvage treatment and adoptive immunotherapy in 15 cases, while 5 pts received a second transplant from a different donor. Up to 155 pts transplanted in PD, 37 (24%) are alive with a median follow-up of 499 days, of these 22 pts received a haplo-SCT, 8 MUD, 6 MRD, 1 UCB. The median follow-up for pts dead is of 118 days (range 2–2315), the cause of death were disease relapse (53,26%), graft-versus-host-disease (8,7%), infection (31,5%), multi organ failure (3,8%), cardiovascular disease (1,09%), haemorrhage (1,63%). Conclusion. In ITT analysis, 81% of overall pts candidate received an allo-SCT (59% from an alternative donor, 22% from a MRD) and the outcome achieved for pts transplanted in CR is comparable within the three major donor source (MRD – MUD – haplo-SCT). This result confirm the need to offer to every candidate pts a transplant option in the appropriate time, but also support the use of alternative donors, particularly haplo-SCT, in absence of an available MRD or MUD. The highly committed policy performed in the alternative-SCT setting and the implementation of an alternative donor option are essential prerequisite to obtain these results, offering to every candidate pts a concrete opportunity of treatment. Disclosures: Bordignon: Molmed: Employment.