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Mucopolysaccharidosis IVA (MPS IVA; Morquio syndrome) is a lysosomal storage disorder and features systemic skeletal dysplasia that is caused by defective Nacetylgalactosamine-6-sulfate sulfatase (GALNS). Although there are convincing data for hematopoietic stem cell transplantation (HSCT) in certain types of MPS, the studies are limited for MPS IVA and more data is still pending to show the efficacy/safety of HSCT. This study included 3 girls and 7 boys, with a median age of 75,5 months (35–186 months), who underwent allogeneic HSCT for severe MPS IVA between February 12, 2021, and March 10, 2023. Enzyme levels, height growth, the most involved organs (ear, eye, and heart), and the activities of daily living (ADL) scoring system were monitored to assess the benefit of HSCT. In a median follow-up of 20 months (9–34 months), there is no severe transplant-related adverse event was observed. In all cases, normal enzyme levels were reached after HSCT. During the short follow-up period, our cases showed an increase in stature and improvement in daily activity functions. Here we present the data of our HSCT experience in MPS IVA with promising results regarding both safety and efficacy. Although there are signs of amelioration with HSCT, we need more data and long-term follow-up to comment properly on the benefits of HSCT in MPS IVA.

Major histocompatibility complex class II deficiency, a combined immunodeficiency, results from loss of HLA class II expression on antigen-presenting cells. Currently, hematopoietic stem cell transplantation stands as the sole curative approach, although factors influencing patient outcomes remain insufficiently explored.

We report the national data on the outcomes of hematopoietic stem cell transplantation (HSCT) for thalassemia major (TM) patients in Turkey on behalf of the Turkish Pediatric Stem Cell Transplantation Group. We retrospectively enrolled 1469 patients with TM who underwent their first HSCT between 1988 and 2020 in 25 pediatric centers in Turkey. The median follow-up duration and transplant ages were 62 months and 7 years, respectively; 113 patients had chronic graft versus host disease (cGVHD) and the cGVHD rate was 8.3% in surviving patients. Upon the last visit, 30 patients still had cGvHD (2.2%). The 5-year overall survival (OS), thalassemia-free survival (TFS) and thalassemia-GVHD-free survival (TGFS) rates were 92.3%, 82.1%, and 80.8%, respectively. cGVHD incidence was significantly lower in the mixed chimerism (MC) group compared to the complete chimerism (CC) group (p< 0.001). In survival analysis, OS, TFS, and TGFS rates were significantly higher for transplants after 2010. TFS and TGFS rates were better for patients under 7 years and at centers that had performed over 100 thalassemia transplants. Transplants from matched unrelated donors had significantly higher TFS rates. We recommend HSCT before 7 years old in thalassemia patients who have a matched donor for improved outcomes.

Currently, there is no guideline for the treatment of patients with congenital dyserythropoietic anemia (CDA) type II. One approach is to follow-up patients with transfusions, on the basis of individually determined target hemoglobin levels, and iron chelation according to the thalassemia guidelines. In some transfusion-dependent CDA II patients, splenectomy reduces the number of transfusions; however, the only known curative option for CDA II patients is hematopoietic stem cell transplantation (HSCT). Only a few published case reports of allogeneic HSCT in CDA II patients are available. Here, we review the literature and add our data of a CDA II patient who developed transfusion dependence and was cured with HSCT.

Mutations in interleukin-10 and its receptors cause infantile inflammatory bowel disease (IBD), a hyperinflammatory disorder characterized by severe, treatment-refractory colitis, multiple abscesses, and enterocutaneous fistulas. Patients with infantile IBD often require several surgical interventions, including complete colectomy, and hematopoietic stem cell transplantation is currently the only known medical therapy. Traditionally, operative management has been preferred before stem cell transplantation because of the latter’s increased susceptibility to procedural complications; however, surgical intervention could be delayed, and possibly reconsidered, because our 2 patients with infantile IBD demonstrated a rapid response to treatment via engraftment.

Immune reconstitution inflammatory syndrome (IRIS) is a clinical condition emerging after immune recovery of an immunocompromised status, mostly in human immunodeficiency virus infected patients but also in several other settings, such as the recovery from the severe combined immunodeficiency status after hematopoietic stem cell transplantation. Herein, we report a patient transplanted for severe combined immunodeficiency who developed IRIS for 2 times, namely shortly after transplantation and after donor lymphocyte infusion. Pediatric transplant teams need to be aware of the previous IRIS phenomenon of BCG-adenitis while making the decision of donor lymphocyte infusions.

Extracorporeal photopheresis (ECP) is a difficult procedure to perform in the pediatric population. This is a retrospective review of 12 pediatric patients who underwent photopheresis with the Therakos Cellex system for graft-versus-host disease (GVHD). Acute GVHD (aGVHD) occurred in 6 patients, and overlap syndrome and chronic GVHD (cGVHD) occurred in 4 and 2 patients, respectively. The ECP regimen was the same for all aGVHD and cGVHD patients: initially, every week (2 sessionswk) for 2 months; next, every 2 weeks for 2 months; and finally, every month for at least 1 year. Improvement was observed in 7 of 10 aGVHD patients (70) and in 4 of 6 cGVHD patients (66). Eleven patients had skin involvement before ECP; 9 of them responded to treatment (81). Gastrointestinal involvement occurred in 8 patients; 5 of them experienced improvement during ECP treatment (62). All 4 patients with liver involvement failed to respond. No serious adverse reactions occurred. In conclusion, our study demonstrates that ECP with the Therakos Cellex system is a safe treatment option for GVHD in children, allowing the tapering of immunosuppressants by at least half.

There is limited data about the long-term treatment outcome and prognosis of childhood acute lymphoblastic leukemia (ALL) in developing countries. Our study was designed to assess survival data and identify risk factors. Data of 142 children with ALL who were treated with a modified BFM 95 protocol between 1997 and 2007 were evaluated. The median age was 4.3 years. Complete remission (CR) rate after induction phase was 93.5; with 2.1 induction-related mortality and 0.7 having resistance disease. Of complete responders, 67.1 are in continuous CR with a median follow-up of 63 months (range 24 to 153 mo). Treatment-related mortality was 17.7 and the total rate of treatment abandonment was 3.5. The probability of event-free survival was 67.3 (95 confidence interval 59.3-75.3) at 4 years and 63.2 (95 confidence interval 54.4-72.0) at 8 years. This report examines children with ALL treated with a modified ALL-BFM 95 protocol in a tertiary care center in Turkey with adequate follow up and demonstrates the need for improvements especially for patients with unfavorable risk group and strategies to reduce deaths from infection in CR to keep pace with cure rates in developed countries.

Several investigators have been looking for less toxic conditioning regimen for stem cell transplantation in Fanconi anemia (FA) patients because of sensitivity to DNA cross-linking agents and tendency to malignancy. We report 16 multitransfused FA patients who underwent peripheral stem cell transplantation from 13 related and 3 unrelated donors. Although the first 6 patients received thoraco-abdominal irradiation cyclophosphamide antithymocyte globulin (regimen A) for conditioning, fludarabine (FLU) cyclophosphamide antithymocyte globulin (regimen B) were used in the last 10 patients in which 3 of them received unrelated graft. Cyclosporin A was given alone for the related allografts but also included mycophenolate mofetil for the unrelated allograft as graft versus host disease prophylaxis. We observed a lower risk of peritransplant morbidity and mortality with fewer and milder graft versus host disease in FLU based group. We lost 3 patients in regimen A group and 1 of them from secondary acute myeloid leukemia. Three patients are alive with transfusion independent. In regimen B group, 9 of 10 patients are alive with normal hematologic parameters and full donor chimerism. The longest follow-up durations are 90 and 60 months in regimen A and B, respectively. In conclusion, FLU based conditioning is more effective and successful with lower toxicity in multitransfused FA patients. However, it needs more experience and longer follow up duration.

Higher mortality and morbidity are well established in children with malignancies in whom intensive care admissions are required. A retrospective cohort study was conducted to assess the risk factors for children with cancer in the pediatric intensive care unit (PICU) for short-term outcome (survival vs. nonsurvival when leaving the PICU). The records of 36 children with a median age of 5 years (range 0.5 to 21) between August 2004 and August 2007 were reviewed. Mortality rate was 55, higher than the yearly overall PICU mortality rate of 12 (P<0.0001). The mean Pediatric Risk of Mortality Score (PRISM) III score among survivors was lower than that among nonsurvivors (9.4±5.7 vs. 16.4±5.3, P0.001). Comparison of observed and predicted mortality derived from the PRISM III score showed that distribution of outcome was not different and the prediction model performed well (goodness of fit test χ23.64, df6, P0.725). The mortality rates were 66.6 and 33.3 in patients with high (>10 points) and low (≤10 points) PRISM III score, respectively (P0.05). Mortality rate was significantly related to presence and number of organ system dysfunction (P0.031 and P0.013, respectively), sepsis (P0.05), mechanical ventilation (P0.005), and positive inotropic support (P0.003). By using multiple logistic regressions, the independent risk factor was PRISM III score at the time of admission to PICU (P0.05). The PRISM III score performed well as a predictor of outcome. For decision to admit such patients to the PICU or to forgo life-sustaining therapies, other factors such as need for mechanical ventilation and positive inotropic support, presence and numbers of organ system dysfunction should be taken into consideration as well.

•Isolated extramedullary relapse (iEMR) is a frequent and significant relapse event.•Compared with systemic relapse, iEMR manifests clinically after systemic relapse.•Central nervous system iEMR is the most common subtype of iEMR in both acute lymphoblastic leukemia and acute myelogenous leukemia.•Risk factors, pathophysiology, and outcomes of iEMR differ from those of systemic relapse.•Current evidence shows the use of total body irradiation in HSCT conditioning may be more effective at preventing post-HSCT relapse than chemotherapy alone-based conditioning.

Dag: Novartis: Employment. Birkent:Novartis: Employment.

No relevant conflicts of interest to declare.

No relevant conflicts of interest to declare.

Background:Graft-versus-host disease (GVHD) is a serious complication with a significant negative impact on survival following allogeneic hematopoietic stem cell transplantation (HSCT) in both adults and children. Immunosuppressants like steroids remain the mainstay of treatment which carries risks of increased infection frequency, a negative impact on the graft-versus-leukemia effect, and an increased probability of secondary malignancies. Extracorporeal photopheresis (ECP) treatment, seems to ameliorate GVHD by immunomodulation, rather than immunosuppression. However it is difficult to perform in pediatric population. This is a retrospective review of 17 pediatric patients who underwent photopheresis with the Therakos Cellex system for graft-versus-host disease (GVHD).

Umbilical cord blood (CB) are increasingly used for allogeneic transplantation as an alternative source to bone marrow or peripheral stem cell for patients who lack a human leucocyte antigen (HLA)-matched donor. Cell dose is one of the main determinant factor for selection of the unit and it has been shown to correlate with time and probability of engraftment. Cell doses available for selection of the unit are the ones evaluated before cryopreservation. Processing of the graft either with cryopreservation and/or thawing inevitably lead to cell loss but the data showing to what extent is very limited although this has great importance especially for the units with critical cell counts. To evaluate the extent of the cell loss after thawing and the effect of preservation duration on cell loss and the viability, we retrospectively analyzed our single center experience in a cohort of patients receivingunrelated CBT.

No relevant conflicts of interest to declare.

Abstract 4521

Veno-occlusive disease (VOD) of the liver is a major complication of allogeneic or autologous stem cell transplantation (HSCT), particularly after busulfan-based conditioning regimens. Clinically, VOD is characterized by fluid retention, weight gain, hyperbilirubinemia and painful hepatomegaly. Efficacy and safety of defibrotide for the treatment of VOD, especially in pediatric patients, has not been adequately confirmed or the results are still preliminary. This retrospective report describes experience with defibrotide in children with hepatic veno-occlusive disease (HVOD) following HSCT in a single institution. Materials and Method: Children who had undergone HSCT between April 2005–June 2006 and who received defibrotide for the treatment of HVOD during their admission were identified. Demographic data and clinical information of these patients were abstracted from their health records. Results: Eight children (median age: 4.5 years; range: 1–14 years) who underwent HSCT during the study period received defibrotide for the treatment of HVOD; 5 were boys and 3 were girls. Three patients underwent HSCT for hematologic malignancies, 2 for neuroblastoma, 1 for hemoglobinopathy, 1 for severe combined immunodeficiency (SCID) and 1 for fanconi aplastic anemia. Conditioning regimens included busulfan (16 mg/kg) in four, melphelan (140 mg/m2) in two and total body irradiation in 1 patient as being risk factors for HVOD. Two patients with neuroblastoma had undergone autologous HSCT, three patients had been transplanted from matched sibling donor and the other three were either unrelated donor or unrelated cord blood transplantation. HVOD was diagnosed on transplant day +4 to +19 (median: +12 ). The median initial defibrotide dose was 31.5 mg/kg/day (25–46 mg/kg/day). The median duration of defibrotide therapy was 27 days (1–46 days). Defibrotide was discontinued due to clinical improvement (5), gastrointestinal hemorrhage (2), death (1). Two patients in whom defibrotide was discontinued because of gastrointestinal hemorrhage died. The primary cause of death in these two children was: progressive HVOD and multiorgan failue following sepsis. As a result of this experience and under the light of literature, we believed that defibrotide is an effective treatment for children with HVOD and should be instituted in each children without delay in the event of at least one of the criteria for HVOD is established. But it is necessary to carry out further studies in larger group of patients with longer follow-up to validate the efficacy and safety of defibrotide.

Although improvements in conventional treatment have enhanced the prognosis of thalassaemia, stem cell transplantation remains the only cure. Studies have shown that peripheral blood stem cell transplantation (PBSCT) results in rapid hematological and immunological recovery but increased risk for graft versus host disease (GVHD). We report the PBSCT experience of Akdeniz University School of Medicine Pediatric Hematology&Oncology department concerning 54 patients with beta-thalessemia. Median age was 6 years (1–18 years), 26 were girls, 28 were boys. Thirteen were Class I, twenty-two were Class II, nineteen were Class III according to Pesaro criteria. 12 patients were given BU+CY and 39 BU+CY plus ATG as conditioning regimen. Three Class III patients were conditioned with Pesaro protocol 26. BU dosage was 16 mg/kg for Class I and Class II patients followed by CY 200 mg/kg totally. Class III patients received 14 mg/kg BU and 160 mg/kg CY. All patients received MTX (+1, +3, +6) and CsA for GVHD prophylaxis. All of the donors were HLA identical (51 sibling, 3 parents). Median age of the donors was 7 years (range: 2–40 years). G-CSF was given for 5 days with the dosage of 5 μgr/kg/day to child and 10 μgr/kg/day to adult donors for peripheral blood stem cell mobilization. Stem cell apheresis was performed on fifth day, but continued to day 7 if adequate cell count was not achieved. In older children and parents if appropriate, antecubital veins were used for harvesting but for younger donors, femoral dual lumen catheters were emplaced. Fresenius AS. TEC204 or Haemonetics MCS+ cell separators were used for apheresis. The median apheresis count was 1 (range 1–3). Median transfused MNC and CD34 cell counts were 10.1×108/kg (range:5.3–27.7×108/kg) and 4,65×106/kg (range:1.1–29.4×106 /kg) respectively. Median neutrophil and platelet engraftment times were day 14 and day 15, respectively. Grade II–IV acute GVHD were observed in five patients, chronic GVHD were in four of two were extensive. One patient died on posttransplant day 32 because of acute GVHD. Death because of chronic GVHD was not observed. At a median follow-up of 26 months (1–92 months), overall survival for the whole group is 92.6 % and evet-free survival is %80.4. Autologous reconstitution developed in six patients and graft failure in two.

Although improvements in conventional treatment have enhanced the prognosis of thalassaemia, stem cell transplantation remains the only cure. Studies have shown that peripheral blood stem cell transplantation (PBSCT) results in rapid hematological and immunological recovery but increased risk for graft versus host disease (GVHD). We report the PBSCT experience of Akdeniz University School of Medicine Pediatric Hematology&Oncology department concerning 54 patients with beta-thalessemia. Median age was 6 years (1–18 years), 26 were girls, 28 were boys. Thirteen were Class I, twenty-two were Class II, nineteen were Class III according to Pesaro criteria. 12 patients were given BU+CY and 39 BU+CY plus ATG as conditioning regimen. Three Class III patients were conditioned with Pesaro protocol 26. BU dosage was 16 mg/kg for Class I and Class II patients followed by CY 200 mg/kg totally. Class III patients received 14 mg/kg BU and 160 mg/kg CY. All patients received MTX (+1, +3, +6) and CsA for GVHD prophylaxis. All of the donors were HLA identical (51 sibling, 3 parents). Median age of the donors was 7 years (range: 2–40 years). G-CSF was given for 5 days with the dosage of 5 μgr/kg/day to child and 10 μgr/kg/day to adult donors for peripheral blood stem cell mobilization. Stem cell apheresis was performed on fifth day, but continued to day 7 if adequate cell count was not achieved. In older children and parents if appropriate, antecubital veins were used for harvesting but for younger donors, femoral dual lumen catheters were emplaced. Fresenius AS. TEC204 or Haemonetics MCS+ cell separators were used for apheresis. The median apheresis count was 1 (range 1–3). Median transfused MNC and CD34 cell counts were 10.1×108/kg (range:5.3–27.7×108/kg) and 4,65×106/kg (range:1.1–29.4×106/kg) respectively. Median neutrophil and platelet engraftment times were day 14 and day 15, respectively. Grade II–IV acute GVHD were observed in five patients, chronic GVHD were in four of two were extensive. One patient died on posttransplant day 32 because of acute GVHD. Death because of chronic GVHD was not observed. At a median follow-up of 26 months (1–92 months), overall survival for the whole group is 92.6 % and evet-free survival is %80.4. Autologous reconstitution developed in six patients and graft failure in two.

Veno-occlusive disease (VOD) of the liver is a major complication of allogeneic or autologous stem cell transplantation (HSCT), particularly after busulfan-based conditioning regimens. Clinically, VOD is characterized by fluid retention, weight gain, hyperbilirubinemia and painful hepatomegaly. Efficacy and safety of defibrotide for the treatment of VOD, especially in pediatric patients, has not been adequately confirmed or the results are still preliminary. This retrospective report describes experience with defibrotide in children with hepatic veno-occlusive disease (HVOD) following HSCT in a single institution.

High dose chemo-radiotherapy followed by either allogeneic or autologous hematopoietic stem cell transplantation (HSCT) is the treatment of choice for an increasing number of congenital or acquired diseases of childhood. One of the major drawbacks of this procedure is the prolonged period of profound neutropenia and complications associated with neutropenia. Although administration of granulocyte colony-stimulating factor (G-CSF) to adult patients undergoing high-dose chemotherapy and HSCT is believed to accelerate neutrophil recovery, the actual clinical benefits of G-CSF in children remain a controversial point requiring controlled studies and also the optimal timing for G-CSF infusion has not been established yet. It is well-known that children frequently recover faster than adults after HSCT and suffer less from life-threatening infections. In addition, studies demonstrating that these cytokines may also modify T-cell and dendritic cell function brought about a question whether the effect is strong enough to alter the risk of graft-versus-host disease (GVHD).

High dose chemo-radiotherapy followed by either allogeneic or autologous hematopoietic stem cell transplantation (HSCT) is the treatment of choice for an increasing number of congenital or acquired diseases of childhood. One of the major drawbacks of this procedure is the prolonged period of profound neutropenia and complications associated with neutropenia. Although administration of granulocyte colony-stimulating factor (G-CSF) to adult patients undergoing high-dose chemotherapy and HSCT is believed to accelerate neutrophil recovery, the actual clinical benefits of G-CSF in children remain a controversial point requiring controlled studies and also the optimal timing for G-CSF infusion has not been established yet. It is well-known that children frequently recover faster than adults after HSCT and suffer less from life-threatening infections. In addition, studies demonstrating that these cytokines may also modify T-cell and dendritic cell function brought about a question whether the effect is strong enough to alter the risk of graft-versus-host disease (GVHD). In this retrospective three armed study we reviewed our experience at Akdeniz University School of Medicine Pediatric Hematology/Oncology Department to determine whether G-CSF administration on posttransplant period affects neutrophil and platelet engrafment time and alters the risk of acute or chronic GVHD in a relatively homogeneous nonmalignant group, thalassemia major patients. Fortyseven patients transplanted with peripheral blood stem cells were studied. G-CSF, if administered, were started on posttransplant day 1 or day 5. 25 patients in day 1 and 11 patients in day 5 group with other 11 non-administered patients were revealed retrospectively in respect to main outcomes that were hematopoietic recovery (neutrophil and platelet recovery defined by a neutrophil count of ≥0.5x109/L for 3 consecutive days and nontransfused platelet count of ≥20x109/L for 7 consecutive days) and GVHD. They were all given methotrexate combined with cyclosporine as GVHD prophylaxis with ATG in 35 patients. In G-CSF non-administered group neutrophil recovery was delayed compared with G-CSF administered group (16.5±2.8 vs 13.8±3.6 p=0.009) although transplanted MNC count was higher (16.8±3.5 vs 9.4±4.1 p<0.001). Although there was no any significant difference, platelet recovery seems to delay in G-CSF group (15.9±7.1 vs 21.8±14.5 p>0.05). The mean days to neutrophil recovery (14.0 ±3.7 vs 3.7±3.5 p>0.05) and the mean days to platelet recovery (22.7±15.5 vs 19.8±12.6 p>0.05) were not significantly different between day 1 and day 5 group. There were 5 grade II-IV acute and 5 chronic GVHD, both in G-CSF administered group but there were not any statistical differences in respect to GVHD between G-CSF or non-administered group and also within the G-CSF administered group according to administration time. In conclusion, administration of G-CSF after allogeneic PBSCT in children with thalassemia cause faster neutrophil recovery but administration on day 1 seems as if there is no additive effect compared to day 5 and do not alter the risk of acute or chronic GVHD. More studies in larger scales are needed to determine whether greater delay or non-use is feasible or not.