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Myeloproliferative disease; Paediatrics Enfermedad mieloproliferativa; Pediatría Malaltia mieloproliferativa; Pediatria Open Access funding enabled and organized by Projekt DEAL.

Terminal complement blockade by humanised monoclonal antibody eculizumab has been used to treat transplantation-associated thrombotic microangiopathy (TA-TMA) in recent years. This retrospective international study conducted by the Paediatric Diseases (PDWP) and Inborn Error Working Party (IEWP) of the European Society for Blood and Marrow Transplantation (EBMT) describes outcome and response of 82 paediatric patients from 29 centres who developed TA-TMA and were treated with eculizumab between January 2014 and May 2019. The median time from hematopoietic stem cell transplantation (HSCT) to TA-TMA manifestation was 92 days (range: 7-606) and from TA-TMA diagnosis to the start of eculizumab treatment 6 days (range: 0-135). Most patients received eculizumab weekly (72%, n = 55) with a standard weight (kg)-based dose (78%, n = 64). Six months from beginning of eculizumab therapy, the cumulative incidence of TA-TMA resolution was 36.6% (95% CI: 26.2-47) and the overall survival (OS) was 47.1% (95% CI: 35.9-57.5). All 43 patients with unresolved TA-TMA died. The cause of death was HSCT-related in 41 patients. This study also documents poor outcome of patients without aGvHD and their frequent concomitant viral infections. Considering recent publications, intensified eculizumab dosing and complement monitoring could potentially improve upon outcomes observed in this study.

Aktuelle gesellschaftliche und (medien)technologische Prozesse des globalen Wandels liefern ausreichend Begrundungen furdie dringende Notwendigkeit einer Thematisierung der Aushandlung von Identitaten im Schulunterricht. Dieses Bildungsanliegeneiner Dekonstruktion und Reflexion von Identitatskonzepten mit Jugendlichen kann mit Anliegen der kritischenMedienbildung erkenntnisreich in Einklang gebracht werden. Da vergleichbare Ziele bereits in mehreren osterreichischenUnterrichtsprinzipien und Lehrplanen und damit explizit in den schulrechtlichen Rahmungen des osterreichischen Schulunterrichtsverankert sind, verwundert die Beobachtung umso mehr, dass adaquate Bildungsbemuhungen, etwa in Schulbuchernund Materialien zur digitalen Grundbildung, erst wenig Niederschlag gefunden haben.2 Ausgehend vom ProjektMiDENTITY wird aufgezeigt, wie schulische Aufgriffe zu Identitatskonstruktion von Jugendlichen und kritische (geographische)Medienbildung fachdidaktisch gerahmt werden konnen. Schlieslich versteht sich der Beitrag auch als Motivationfur Lehrpersonen an der Schliesung der Forschungs- und Praxislucke mitzuwirken.

The abstract is available here: https://uscholar.univie.ac.at/o:1637059

Acute appendicitis is a rare gastrointestinal complication of anti-cancer chemotherapy and hematopoietic stem cell transplantation. Among a cohort of 2341 hemato-oncologic patients at a pediatric tertiary care cancer center, we identified 21 patients (0.9%) with 23 episodes of acute appendicitis, based on pathological imaging of the appendix and clinical findings. Median age at diagnosis was 10.21 years. Types of underlying disease included acute leukemias (n = 15), solid tumors (n = 4), and aplastic anemia (n = 2). Clinical symptoms seen in > 1 case were recorded for all 23 episodes as follows: abdominal pain, n = 22; abdominal tenderness, n = 4; fever, n = 7; nausea, n = 2; emesis; n = 2; diarrhea, n = 5; and constipation, n = 2. Median leukocyte count at diagnosis was 0.5 × 109/L, with a median of 0.1 × 109/L for the absolute neutrophil count (ANC). All patients received broad-spectrum antibiotics and 18/23 (78%) patients underwent uneventful appendectomy after a median of 5 days and with a median ANC of 0.7 × 109/L. Median duration until continuation of chemotherapy was 17 days for the 20 cases of appendicitis occurring during the patients’ disease course. Overall, 5/21 (19%) patients died including one related to the appendicitis itself which progressed to a typhlitis and was due to a fungal infection. The other fatalities were transplant- (n = 2) and leukemia-related (n = 2). Acute appendicitis is a rare and usually not life-threatening event in pediatric hemato-oncologic patients, which, if managed by prompt administration of broad-spectrum antibiotics (and antimycotics), can be safely followed by an elective (delayed) appendectomy, even before complete recovery of the neutrophils is achieved.

Therapy of children with post‐transplantation lymphoproliferative disorder (PTLD) after hematopoietic stem cell (HSCT) and solid organ transplantation (SOT) can be challenging. In this retrospective study, we investigated PD‐L1 and PD1 expression in all PTLD categories of childhood and adolescence to see whether checkpoint inhibition with PD‐L1/PD1 inhibitors may serve as a therapy option. We included 21 patients aged 19 years or younger (at date of transplant) with PTLD following SOT or HSCT having adequate tumor samples available (n = 29). Using immunohistochemistry, we evaluated PD‐L1/PD1 expression on both tumor cells and cells of the microenvironment in all samples. Availability of consecutively matched tumor samples during 6 of 21 patients' disease courses also allowed an intra‐individual assessment of PD‐L1/PD1 expression. We observed lower PD‐L1 and higher PD1 expression in non‐destructive lesions, and higher PD‐L1 and lower PD1 expression in polymorphic and, in particular, in monomorphic PTLD, mostly diffuse large B‐cell lymphomas (DLBCL, n = 10/21). The amount of PD‐L1‐ and PD1‐positive cells changed in the opposite way in sequential biopsies of the same individual correlating well with the PTLD category. This is the first comprehensive pediatric study assessing PD‐L1 and PD1 expression on tumor cells and in the microenvironment of PTLD including not only monomorphic, but also non‐destructive early lesions. PD‐L1 expression of the tumor cells inversely correlated with PD1 expression in surrounding tissues, with the highest expression in DLBCL. Since PTLD can be therapeutically challenging, our results indicate a potential efficacy of checkpoint inhibitors if standard immune‐ and/or chemotherapy fail or are impossible. We therefore recommend routine staining of PD‐L1 and PD1 in all PTLD categories.

Although allogeneic hematopoietic stem-cell transplantation (HSCT) provides high cure rates for children with high-risk acute lymphoblastic leukaemia (ALL), relapses remain the main cause of treatment failure. Whereas donor killer cell immunoglobulin-like receptor (KIR) genotype was shown to impact on relapse incidence in adult myeloid leukaemia similar studies in paediatric ALL are largely missing. Effect of donor KIR genotype on transplant outcome was evaluated in 317 children receiving a first myeloablative HSCT from an HLA-matched unrelated donor or sibling within the prospective ALL-SCT-BFM-2003 trial. Analysis of donor KIR gene polymorphism revealed that centromeric presence and telomeric absence of KIR B haplotypes was associated with reduced relapse risk. A centromeric/telomeric KIR score (ct-KIR score) integrating these observations correlated with relapse risk (hazard ratio (HR) 0.58; P = 0.002) while it had no impact on graft-versus-host disease or non-relapse mortality. In multivariable analyses ct-KIR score was associated with reduced relapse risk (HR 0.58; P = 0.003) and a trend towards improved event-free survival (HR 0.76; P = 0.059). This effect proved independent of MRD level prior to HSCT. Our data suggest that in children with ALL undergoing HSCT after myeloablative conditioning, donor selection based on KIR genotyping holds promise to improve clinical outcome by decreasing relapse risk and prolonged event-free survival.

The abstract is available here: https://uscholar.univie.ac.at/o:1087564

Background Management of pediatric post‐transplantation lymphoproliferative disorder (PTLD) after hematopoietic stem cell (HSCT) and solid organ transplantation (SOT) is challenging. Aim This study of 34 PTLD patients up to 19‐years old diagnosed in Austria from 2000 to 2018 aimed at assessing initial characteristics, therapy, response, and outcome as well as prognostic markers of this rare pediatric disease. Methods and results A retrospective data analysis was performed. Types of allografts were kidney (n = 12), liver (n = 7), heart (n = 5), hematopoietic stem cells (n = 4), lungs (n = 2), multi‐visceral (n = 2), small intestine (n = 1), and vessels (n = 1). Eighteen/34 were classified as monomorphic PTLD, with DLBCL accounting for 15 cases. Polymorphic disease occurred in nine, and non‐destructive lesions in six cases. One patient had a non‐classifiable PTLD. Thirteen/34 patients are surviving event‐free in first remission (non‐destructive, n = 4/6; polymorphic, n = 4/9; monomorphic, n = 6/18). Fourteen/34 patients lacked complete response to first‐line therapy, of whom seven died. Four/34 patients relapsed, of whom two died. In 3/34 patients, death occurred as a first event. The 5‐year overall and event‐free survival rates were 64% ± 9% and 35% ± 9% for the whole cohort. Among all parameters analyzed, only malignant disease as the indication for transplantation had a significantly poor influence on survival. Conclusions This study shows PTLD still to be a major cause of mortality following SOT or HSCT in children. A continued understanding of the molecular biology of the disease shall allow to decrease treatment intensity for lower risk patients and to identify patients who may benefit from newer therapy approaches to improve outcome and decrease morbidity.

The importance of viral infections as a leading cause of morbidity and mortality is well documented in severely immunosuppressed patients undergoing allogeneic stem cell transplantation. By contrast, viral infections generally receive less attention in patients with malignant disorders undergoing chemotherapy, where the onset of neutropenic fever is mostly associated with bacterial or fungal infections, and screening for viral infections is not routinely performed. To address the occurrence of invasive viral infections in a clinical setting commonly associated with less pronounced immunosuppression, we have prospectively screened 237 febrile neutropenic episodes in pediatric (n = 77) and adult (n = 69) patients undergoing intensive chemotherapy, primarily for treatment of acute leukemia. Serial peripheral blood specimens were tested by RQ-PCR assays for the presence and quantity of the clinically relevant viruses CMV, EBV, HHV6 and HAdV, commonly reactivated in highly immunocompromised patients. Viremia was documented in 36 (15%) episodes investigated, including the detection of HHV6 (n = 14), EBV (n = 15), CMV (n = 6), or HAdV (n = 1). While low or intermediate levels of viremia (104 copies/mL) was documented in patients without evidence for other infections, raising the possibility that at least in some instances the onset of fever may have been attributable to the virus detected. The observations suggest that viral infections, potentially resulting from reactivation, might also play a clinically relevant role in patients receiving chemotherapy for treatment of malignant neoplasms, and routine screening for viremia in this clinical setting might be warranted.

STUDY QUESTION What are the characteristics of patients with conceptions transplanted in childhood and adolescence? SUMMARY ANSWER Insemination and conception after hematopoietic stem cell transplantation (HCT) in childhood or adolescence was possible, even after myeloablative conditioning regimes, although some patients required reproductive medicine support. WHAT IS KNOWN ALREADY Preparative regimens of HCT are highly gonadotoxic, which leads to gonadal failure and pubertal development disorders. There are few population-based studies assessing the risk of future infertility in children after HCT. STUDY DESIGN, SIZE, DURATION We conducted a retrospective study to investigate natural or assisted conceptions and their outcomes in patients PARTICIPANTS/MATERIALS, SETTING, METHODS Detailed information concerning pregnancy occurrences and outcomes were obtained by a separate questionnaire. Quantitative variables were presented as medians with their interquartile range (IQR) or range, and categorical variables were presented as frequencies and percentages. MAIN RESULTS AND THE ROLE OF CHANCE In total, 62 988 pediatric patients received a first HCT in EBMT centers between 1995 and 2016. Pregnancy was reported in 406 patients in the database. The median age at transplantation was 15.7 (range: 0.7–18) years, and the median age at declared conception was 25.0 (range: 16.3–38.8) years. Details concerning the first pregnancy and pregnancy outcome were obtained from 99 patients (24%) from the returned questionnaires. The median age at delivery or pregnancy interruption of the females was 23.0 (IQR: 20.8–27) years, with a median time after transplant of 10.7 (IQR: 6.6–15.4) years. Compared with the mean age of healthy women at their first child’s birth (29 years old), the transplanted women delivered 5 years earlier (mean: 24.3 years). In terms of conception modality, 13/25 (52%) females conditioned with total body irradiation (TBI) and 50/52 (96%) of those conditioned without TBI conceived naturally. All seven male patients who had been conditioned with TBI achieved fatherhood but required assisted fertilization or used their cryopreserved sperm. In the females, 63/70 (90%) of all conceptions resulted in a live birth, 49/63 (84.5%) were at term and 43/46 (93%) had normal birthweight. Cesarean delivery was performed in 9/61 (15%) especially in women who had received a myeloablative regimen. LIMITATIONS, REASONS FOR CAUTION In the EBMT pediatric dataset, the age at last follow-up or death was WIDER IMPLICATIONS OF THE FINDINGS Reproductive health surveillance and fertility preservation counseling are important in younger transplanted patients. Our results showed that there is a window of opportunity to conceive naturally or with reproductive medicine support. STUDY FUNDING/COMPETING INTEREST(S) Funding was provided by the ‘Stiftung für krebskranke Kinder Regio Basiliensis’, Basel, Switzerland. All authors have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER N/A.

Genetic subgroups; Immune reconstitution; Pretransplantation infections Subgrupos genéticos; Reconstitución inmune; Infecciones previas al trasplante Subgrups genètics; Reconstitució immune; Infeccions prèvies al trasplantament Background Hematopoietic stem cell transplantation (HSCT) represents a curative treatment for patients with severe combined immunodeficiency (SCID), a group of monogenic immune disorders with an otherwise fatal outcome. Objective We performed a comprehensive multicenter analysis of genotype-specific HSCT outcome, including detailed analysis of immune reconstitution (IR) and the predictive value for clinical outcome. Methods HSCT outcome was studied in 338 patients with genetically confirmed SCID who underwent transplantation in 2006-2014 and who were registered in the SCETIDE registry. In a representative subgroup of 152 patients, data on IR and long-term clinical outcome were analyzed. Results Two-year OS was similar with matched family and unrelated donors and better than mismatched donor HSCT (P < .001). The 2-year event-free survival (EFS) was similar in matched and mismatched unrelated donor and less favorable in mismatched related donor (MMRD) HSCT (P < .001). Genetic subgroups did not differ in 2-year OS (P = .1) and EFS (P = .073). In multivariate analysis, pretransplantation infections and use of MMRDs were associated with less favorable OS and EFS. With a median follow-up of 6.2 years (range, 2.0-11.8 years), 73 of 152 patients in the IR cohort were alive and well without Ig dependency. IL-2 receptor gamma chain/Janus kinase 3/IL-7 receptor–deficient SCID, myeloablative conditioning, matched donor HSCT, and naive CD4 T lymphocytes >0.5 × 10e3/μL at +1 year were identified as independent predictors of favorable clinical and immunologic outcome. Conclusion Recent advances in HSCT in SCID patients have resulted in improved OS and EFS in all genotypes and donor types. To achieve a favorable long-term outcome, treatment strategies should aim for optimal naive CD4 T lymphocyte regeneration.

Although most children with acute lymphoblastic leukemia (ALL) receive fractionated total body irradiation (FTBI) as myeloablative conditioning (MAC) for allogeneic hematopoietic stem cell transplantation (allo-HSCT), it is an important matter of debate if chemotherapy can effectively replace FTBI. To compare outcomes after FTBI versus chemotherapy-based conditioning (CC), we performed a retrospective EBMT registry study. Children aged 2–18 years after MAC for first allo-HSCT of bone marrow (BM) or peripheral blood stem cells (PBSC) from matched-related (MRD) or unrelated donors (UD) in first (CR1) or second remission (CR2) between 2000 and 2012 were included. Propensity score weighting was used to control pretreatment imbalances of the observed variables. 3.054 patients were analyzed. CR1 (1.498): median follow-up (FU) after FTBI (1.285) and CC (213) was 6.8 and 6.1 years. Survivals were not significantly different. CR2 (1.556): median FU after FTBI (1.345) and CC (211) was 6.2 years. Outcomes after FTBI were superior as compared with CC with regard to overall survival (OS), leukemia-free survival (LFS), relapse incidence (RI), and nonrelapse mortality (NRM). However, we must emphasize the preliminary character of the results of this retrospective “real-world-practice” study. These findings will be prospectively assessed in the ALL SCTped 2012 FORUM trial.

Analysis of specific leukocyte subsets for post-transplantation monitoring of chimerism provides greater sensitivity and clinical informativeness on dynamic changes in donor- and recipient-derived cells. Limitations of the most commonly used approach to chimerism testing relying on PCR-based analysis of microsatellite markers prompted us to assess the applicability of digital droplet (dd) PCR amplification of deletion/insertion polymorphisms (DIPs) for lineage-specific chimerism testing in the related stem cell transplantation setting, where the identification of informative markers facilitating the discrimination between donor-derived and recipient-derived cells can be challenging. We analyzed 100 genetically related patient-donor pairs by ddPCR analysis using commercially available DIP kits including large sets of polymorphic markers. At least 1 informative marker was identified in all related pairs analyzed, and 2 or more discriminating markers were detected in the majority (82%) of instances. The achievable detection limit is dependent on the number of cells available for analysis and was as low as 0.1% in the presence of ≥20,000 leukocytes available for DNA extraction. Moreover, the reproducibility and accuracy of quantitative chimerism analysis compared favorably to highly optimized microsatellite assays. Thus, the use of ddPCR-based analysis of DIP markers is an attractive approach to lineage-specific monitoring of chimerism in any allogeneic transplantation setting.

Human adenoviruses (HAdV) are a major cause of morbidity and mortality in pediatric human stem cell transplant (HSCT) recipients. Our previous studies identified the gastrointestinal tract as a site of HAdV persistence, but the role of intestinal virus shedding pre-transplant for the risk of ensuing invasive infection has not been entirely elucidated. Molecular HAdV monitoring of serial stool samples using RQ-PCR was performed in 304 children undergoing allogeneic HSCT. Analysis of stool and peripheral blood specimens was performed pre-transplant and at short intervals until day 100 post-HSCT. The virus was detected in the stool of 129 patients (42%), and 42 tested positive already before HSCT. The patients displaying HAdV shedding pre-transplant showed a significantly earlier increase of intestinal HAdV levels above the critical threshold associated with high risk of invasive infection (p, Highlights • Intestinal HAdV persistence confers an increased risk for invasive infection post-HSCT. • In HSCT-recipients with intestinal HAdV shedding, the virus levels mostly increase rapidly during the first days post-HSCT. • Monitoring of HAdV shedding before HSCT is important for identifying patients at high risk for early onset of viremia.

Poster-Abstract

Although most children with acute lymphoblastic leukemia (ALL) receive fractionated total body irradiation (FTBI) as myeloablative conditioning (MAC) for allogeneic hematopoietic stem cell transplantation (allo-HSCT), it is an important matter of debate if chemotherapy can effectively replace FTBI. To compare outcomes after FTBI versus chemotherapy-based conditioning (CC), we performed a retrospective EBMT registry study. Children aged 2-18 years after MAC for first allo-HSCT of bone marrow (BM) or peripheral blood stem cells (PBSC) from matched-related (MRD) or unrelated donors (UD) in first (CR1) or second remission (CR2) between 2000 and 2012 were included. Propensity score weighting was used to control pretreatment imbalances of the observed variables. 3.054 patients were analyzed. CR1 (1.498): median follow-up (FU) after FTBI (1.285) and CC (213) was 6.8 and 6.1 years. Survivals were not significantly different. CR2 (1.556): median FU after FTBI (1.345) and CC (211) was 6.2 years. Outcomes after FTBI were superior as compared with CC with regard to overall survival (OS), leukemia-free survival (LFS), relapse incidence (RI), and nonrelapse mortality (NRM). However, we must emphasize the preliminary character of the results of this retrospective "real-world-practice" study. These findings will be prospectively assessed in the ALL SCTped 2012 FORUM trial.

Veno-occlusive disease (VOD) remains a serious complication after allogeneic hematopoietic stem cell transplantation (HSCT). Prophylactic use of defibrotide (DF) might further reduce VOD rates but has no impact on the incidence of severe VOD or VOD-associated mortality. We investigated the cost-effectiveness of prophylactic DF according to the British Committee for Standards in Haematology/British Society for Blood and Marrow Transplantation guidelines in 348 children who underwent transplantation between 2001 and 2014 in our hospital, 138 of whom were at risk for VOD. The VOD incidence was 7.4% for the total cohort. Patients at risk had a higher incidence of VOD compared with patients without risk factors (15.2% versus 2.4%, P .0001). VOD occurred more often in patients after busulfan-based myeloablative conditioning than in patients after total body irradiation (11.2% versus 3.5%, P = .001). Donor types or the transplantation-related mortality (TRM) risk score did not correlate with VOD incidence. In 81% of patients who responded to therapeutic DF, VOD resolved completely. Overall VOD-associated mortality was .3% for the complete cohort, 3.7% for patients diagnosed with VOD, and 20% for patients with severe VOD. Neither the cumulative incidence of TRM (19% ± 8% versus 17% ± 2%, P = .706) nor the median length of hospitalization differed between patients with VOD and patients without. The median costs per HSCT in patients with VOD were about one-third higher than the overall median costs per transplantation at our institution. The calculated total costs of prophylactic DF treatment for 138 patients at risk was almost 6 times as high as the incremental costs for patients with VOD. We conclude that prophylactic DF for children at risk for VOD is not cost-effective with respect to TRM and length of hospital stay.

Das Wiedererrichten von Grenzzaunen innerhalb Europas im Zuge der Fluchtbewegungen ab 2015 wird zum Ausgangspunkt einer Unterrichtssequenz. Bildimpulse von Grenzzaunen konfrontieren Schuler/innen dabei mit der kontroversen inhaltlichen Aufl adung und den vielfaltigen Wirkungen von Grenzen. Anhand des konkreten Unterrichtsbeispiels wird auch aufgezeigt, wie geographische und okonomische Basiskonzepte die Unterrichtsplanung strukturieren und unterstutzen konnen. Zudem eroff net das Denken und Analysieren entlang von Basiskonzepten fur Schuler/innen ein anschlussfahiges fachliches und methodisches Konzeptwissen, das sich aufgrund einer deutlich langeren Halbwertszeit auch als zukunftsfahig erweisen kann.

Die Erweiterung und Aufbereitung des online verfugbaren genderATLas1 fur den schulischen Einsatz verfolgt zwei Ziele: Einerseits sollen aktuelle wissenschaftliche Erkenntnisse zu genderspezifi schen Fragestellungen aus geographischer, okonomischer, sozialer und politischer Perspektive in Richtung kompetenzorientierten, politisch bildenden Schulunterricht der Sekundarstufen I und II diff undieren. Andererseits fordert die didaktische Aufbereitung das vorwissenschaftliche Arbeiten von Schulerinnen und Schulern (VWA), indem zentrale Elemente eines Forschungsprozesses erlautert werden und zur Eigentatigkeit motiviert und angeleitet wird. Neun altersadaquat aufbereitete, thematische Beitrage machen auf mogliche Forschungsfelder aufmerksam und unterstutzen bei der Formulierung von Forschungsfragen. Ein Set an methodischen Bearbeitungsmoglichkeiten erlaubt individuelle Lern- und Forschungspfade, Schuler/innen werden dabei auch mit Grundlagen der Datenaufbereitung sowie der grafi schen und kartographischen Visualisierung vertraut gemacht. Der genderATlas fur die Schule soll Entdeckungsreisen in gender- bzw. regionalpolitischen Fragestellungen gezielt anregen und unterstutzen.

Background Currently, no estimates can be made on the impact of hematopoietic stem cell transplantation on allergy transfer or cure of the disease. By using component‐resolved diagnosis, we prospectively investigated 50 donor‐recipient pairs undergoing allogeneic stem cell transplantation. This allowed calculating the rate of transfer or maintenance of allergen‐specific responses in the context of stem cell transplantation. Methods Allergen‐specific IgE and IgG to 156 allergens was measured pretransplantation in 50 donors and recipients and at 6, 12 and 24 months in recipients post‐transplantation by allergen microarray. Based on a mixed effects model, we determined risks of transfer of allergen‐specific IgE or IgG responses 24 months post‐transplantation. Results After undergoing stem cell transplantation, 94% of allergen‐specific IgE responses were lost. Two years post‐transplantation, recipients' allergen‐specific IgE was significantly linked to the pretransplantation donor or recipient status. The estimated risk to transfer and maintain individual IgE responses to allergens by stem cell transplantation was 1.7% and 2.3%, respectively. Allergen‐specific IgG, which served as a surrogate marker of maintaining protective IgG responses, was highly associated with the donor's (31.6%) or the recipient's (28%) pretransplantation response. Conclusion Hematopoietic stem cell transplantation profoundly reduces allergen‐specific IgE responses but also comes with a considerable risk to transfer allergen‐specific immune responses. These findings facilitate clinical decision‐making regarding allergic diseases in the context of hematopoietic stem cell transplantation. In addition, it provides prospective data to estimate the risk of transmitting allergen‐specific responses via hematopoietic stem cell transplantation.

Background GATA2 deficiency is an inherited immunodeficiency and predisposition syndrome with a high risk of developing myelodysplastic syndrome (MDS) early in life. Allogeneic hematopoietic stem cell transplantation (HSCT) is presently the only curative therapy for affected patients (pts), but to date there has been no larger study examining in detail outcomes after HSCT for GATA2-related pediatric MDS. Here we report the results of an analysis of pts with a germline GATA2 mutation undergoing HSCT for a diagnosis of MDS enrolled in the registry of the European Working Group of MDS in Childhood (EWOG-MDS). Patients and transplantation procedure Of the 87 pts with GATA2 deficiency registered before the age of 18 years, 66 underwent HSCT between 01/1997 and 11/2018. One pt had to be excluded from the analysis due to lack of data. The 65 remaining pts (34 males/31 females) were transplanted at a median age of 13.5 (4.6-19.9) years. Twenty-seven pts were transplanted for refractory cytopenia of childhood (RCC), while 38 pts had advanced disease. The highest bone marrow (BM) blast percentage prior to HSCT was 5-19% (n=23), 20-29% (n= 9) or >30% blasts (n=5); in one pt with myelofibrotic MDS a blast count was not attainable. Karyotypes included monosomy 7 (n=44), der (1;7) (n=4), trisomy 8 (n=4), random aberration (n=1) or a normal karyotype (n=12). Five of the 38 pts with an increased blast percentage had received intensive AML-type therapy prior to HSCT. Pts were grafted from a matched sibling donor (MSD; n=17), unrelated donor (UD; n=40) or a mismatched family donor (MMFD; n=8). The stem cell source was BM (n=37), peripheral blood (n=27) or cord blood (n=1). Pts were prepared with a busulfan-based (n=35), treosulfan-based (n=21), total body irradiation-based (n=5) or an alternative conditioning regimen (n=4). Results At 5 years the probability of overall survival (pOS) and disease-free survival (DFS) was 0.74 [0.62-0.86] and 0.69 [0.57-0.81], respectively, non-relapse mortality was 0.15 [0.08-0.27] and the cumulative incidence of relapse was 0.16 [0.09-0.29]. All pts engrafted initially. The cumulative incidence of acute graft versus host disease (GVHD) grade II-IV and III-IV was 0.34 [0.24-0.48] and 0.12 [0.06-0.24], respectively, and of overall and extensive chronic GVHD 0.25 [0.16-0.39] and 0.08 [0.03-0.20]. The most common post-transplant infections were viral (39 of the 43 pts with infections) with one pt each with EBV-related post-transplant lymphoproliferative disease and primary CMV disease. There were no mycobacterial infections. The most common non-infectious complications were hepatobiliary (13 pts, including 3 with veno-occlusive disease) and pulmonary (10 pts, 5 of whom had been prepared with a busulfan-based conditioning regimen). Pts with >20% BM blasts showed a trend towards a poorer DFS (0.52 [0.24-0.80]) compared to pts with 5-19% blasts (0.72 [0.53-0.91]) or pts with RCC (0.80 [0.64-0.96]; p=0.15). Examining the influence of karyotype in pts with RCC, there were a total of 2 relapses and 3 deaths (1 after relapse) among the 12 pts with monosomy 7, while there was one event among the 15 RCC pts with a normal karyotype (n=10, 1 death), trisomy 8 (n=3), der (1;7) (n=1) or random aberration (n=1). Limiting the analysis to 9/10 or 10/10 HLA matched-donors, DFS was comparable for pts transplanted from an UD (0.73 [0.55-0.91]) versus a MSD (0.82 [0.64-1.00]). Of the 8 pts transplanted from a MMFD, one patient died after secondary graft failure. No major difference in outcome was seen according to age at HSCT, gender, time from diagnosis to HSCT or stem cell source. Of the five pts who had received AML-type therapy prior to HSCT, three died of a transplant-related cause or relapse. Conclusions and perspectives In summary, HSCT resulted in a pOS of 0.74 in this cohort of children and adolescents with GATA2 deficiency and MDS. Pts with increased blasts had a tendency towards poorer outcomes. The high risk of developing advanced MDS and the better outcome in early stages of the disease indicates that HSCT should be performed early in the clinical course of children diagnosed with GATA2 deficiency and MDS. Of note, there was no indication of excessive toxicity, disease-associated comorbidities or an increased risk of GVHD. The HSCT outcomes of children and adolescents with MDS and GATA2 deficiency are similar to what has been previously published for pts transplanted for MDS in the absence of GATA2 germline disease. Disclosures Bader: Amgen (Brasil), Novartis: Consultancy, Speakers Bureau; Celgene: Consultancy; Medac: Patents & Royalties, Research Funding; Riemser, Neovii: Research Funding. Locatelli:Miltenyi: Honoraria; bluebird bio: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bellicum: Consultancy, Membership on an entity's Board of Directors or advisory committees. Niemeyer:Celgene: Consultancy.

For successful bone marrow transplantation it is necessary to obtain enough progenitor cells during the bone marrow (BM) harvesting procedure. Most centers are using multiple aspirations of maximum 2 ml BM (A), while other centers are using few larger amount aspirations for BM harvesting (B). There is still a discussion about possible differences in graft composition between A and B. To evaluate the feasibility in children we evaluated twenty BM harvestings that were performed in 18 donors, 7 autologous (median age 6.93y; 2.48–16.6) and 13 allogeneic donors (median age 19.75y; 6.45–50.7). A and B were performed crosswise by 2 operators starting with A (2 ml) or B (100 ml) changing to B or A, collecting identically amounts with both methods. We found no statistically significant difference between A and B for MNC, T-cells, and CFU (MNC/ml 824572 versus 725000, p = 0.728; MNC/kg 3.1 10 7 versus 2.9 10 7 , p = 0.296; CD3/ml 162500 versus 300000, p = 0.310; CFU/10 5 MNC 1678 versus 1315, p = 0.094), but for CD34+ cells (CD34/kg 2.62 versus 2.09, p = 0.045). BM harvest by the large amount few punctures method (B) is as sufficient as the commonly used small amount frequent punctures method (A), and could be therefore used equally.

Background and Objectives Our post-thaw cell recovery rates differed substantially in interlaboratory comparisons of identical samples, potentially due to different temperatures during cell staining. Materials and Methods Viable CD34+ cells and leucocyte (WBC) subtypes were quantified by multiparameter single-platform flow cytometry in leucapheresis products collected from 30 adult lymphoma and myeloma patients, and from 10 paediatric patients. After thawing, cells were prepared for analysis within 30 min between thawing and acquisition, at either 4°C or at room temperature. Results For cell products cryopreserved in conventional freezing medium (10% final DMSO), viable cell recovery was clearly lower after staining at 4°C than at RT. Of all WBC subtypes analysed, CD4+ T cells showed the lowest median recovery of 4% (4°C) vs. 25% (RT), followed by CD3, CD34 and CD8 cells. The recovery was highest for CD3γδ cells with 44% (4°C) vs. 71% (RT). In the 10 samples cryopreserved in synthetic freezing medium (5% final DMSO), median recovery rates were 89% for viable CD34 (both at 4°C and RT) and 79% (4°C) vs 68% (RT) for WBC. Conclusions The post-thaw environment and, potentially, the cryoprotectant impact the outcome of cell enumeration, and results from the analysis tube may not be representative of the cells infused into a patient.