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Congenital amegakaryocytic thrombocytopenia is a rare, inherited bone marrow failure syndrome. Allogeneic haematopoietic stem cell transplantation (allo-HSCT) is currently the only curative treatment. In this retrospective study, we analysed 66 patients with allo-HSCT, reported in the European Society for Blood and Marrow Transplantation (EBMT) registry. Bone marrow (BM) was the most widely used stem cell source (n = 40; 61%) followed by peripheral blood (PB) (n = 18; 27%), and unrelated umbilical cord blood (UCB) (n = 8; 12%). Most frequently was a HLA-matched graft from related (n = 26; 39%) and unrelated (n = 15; 23%) donors after a myeloablative busulfan-based conditioning regimen. GvHD prophylaxis was mostly cyclosporine and methotrexate (53%). The 6-year cumulative incidence of graft-failure and second transplant were 25% and 17%, respectively. The 6-year disease-free survival (DFS) and overall survival (OS) were 66.9% and 85.6%, respectively. The 6-year transplant-related mortality (TRM) was 8.0%. In conclusion, most patients with CAMT benefit from allo-HSCT, but with many graft failures., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Anti-T-lymphocyte globulin (ATLG) is used in hematopoietic stem cell transplantation (HSCT) to prevent graft-versus-host disease (GVHD) and graft failure. To date, insight in ATLG pharmacokinetics and -dynamics (PK/PD) is limited, and population PK (POPPK) models are lacking. In this prospective study, we describe ATLG POPPK using NONMEM® and the impact of ATLG exposure on clinical outcome and immune reconstitution in a homogeneous cohort of pediatric acute lymphoblastic leukemia (ALL) patients transplanted with a matched unrelated donor and receiving uniform ATLG dosing. Based on 121 patients and 812 samples for POPPK analysis, a two-compartmental model with parallel linear and non-linear clearance and bodyweight as covariate, best described the ATLG concentration-time data. The level of ATLG exposure (day active ATLG <1 AU/mL, median 16 days post-HSCT) was strongly associated with aGVHD grade II-IV, with a lower incidence in patients with prolonged active ATLG exposure (≤day 16 50% vs. >day 16 8.2%; P<0.001). When stratified for remission state, patients transplanted in complete remission (CR) 2 or 3 with prolonged ATLG exposure had a higher relapse risk, while this effect was not seen in CR1 patients (P=0.010). High level ATLG exposure was associated with delayed CD4 T-cell recovery at 4 and 8 weeks post-HSCT, but not at 12 weeks, and overall and relapse-free survival were not influenced by CD4 recovery at 12 weeks post-HSCT. This study underlines the importance of individualized ATLG exposure with the use of model-informed precision dosing in order to optimize the HSCT outcome in pediatric ALL.

Background: Total body irradiation (TBI) is a pivotal part of conditioning prior to hematopoietic stem cell transplantation (HSCT) for childhood acute lymphoblastic leukemia (ALL), yet evidence is sparse regarding the effect of TBI delivery techniques on acute and late toxicities., Design: In a national cohort of pediatric HSCT-recipients, we compared three TBI schedules; 12 Gray (Gy) delivered as (i) 4 Gy daily fractions from 2008 to 2011 (n = 12); (ii) 2 Gy fractions twice daily with two-dimensional (2D) planning technology from 2012 to 2015 (n = 16); and (iii) 2 Gy twice daily with three-dimensional (3D) planning intensity-modulated radiotherapy (IMRT) from 2016 to 2020 (n = 14)., Results: The 5-year event-free survival was 75.0%, 81.3%, and 81.3% in Cohorts 1, 2, and 3, respectively. Acute toxicity assessed as maximum ferritin and C-reactive protein during the first 3 months post HSCT did not differ between cohorts, nor did the time to first hospital discharge (median 28, 32, and 31 days, p = .25). The incidences of acute graft-versus-host disease (GvHD) (66%, 56%, 71%) and chronic GvHD (25%, 31%, 14%) were comparable. Pulmonary function assessed by spirometry did not differ significantly. The 5-year cataract-free survival was 33.3%, 79%, and 100% in Cohorts 1, 2, and 3, respectively. We found a nonsignificant tendency toward more endocrinopathies in Cohort 1 compared to Cohorts 2 and 3., Conclusion: The change of modality did not result in more relapses. More fractionation led to improvement with a lower incidence of cataract and a tendency toward fewer endocrinopathies. The effect of 3D-planning-IMRT technology requires further evaluation in larger studies., (© 2024 The Author(s). Pediatric Blood & Cancer published by Wiley Periodicals LLC.)

Background: The diagnosis and treatment of childhood acute lymphoblastic leukemia (ALL) may impact mental health. We investigated the long-term risk of psychiatric disorders among survivors of ALL in a population-based cohort study., Methods: We identified patients diagnosed with ALL in Denmark and Sweden before age 20 during 1982-2008. Survivors of ALL (n = 2026), their siblings (n = 3027), and population comparison subjects (n = 9713) were followed for hospital contacts for psychiatric disorders from 5 years after ALL diagnosis (or corresponding index date) until 2017., Results: By age 30, the absolute risk of psychiatric hospital contacts was 19.9% (95% confidence interval [CI]: 17.9-22.1) for ALL survivors, 18.5% (95% CI: 16.9-20.2) for siblings, and 18.3% (95% CI: 17.3-19.2) for population comparison subjects. Overall, survivors were at higher risk of any psychiatric disorders than siblings (hazard ratio [HR] = 1.25; 95% CI: 1.04-1.50), and population comparison subjects (HR = 1.20; 95% CI: 1.06-1.35). The subgroup of survivors (n = 332) who received a hematopoietic stem cell transplantation (HSCT) and/or had a relapse were at highest risk of psychiatric disorders (HR = 2.07; 95% CI: 1.26-3.41 compared to siblings; HR = 1.67; 95% CI: 1.25-2.23 compared to population comparison subjects)., Conclusions: The overall absolute risk of psychiatric hospital contacts among ALL survivors was close to that in siblings and population comparison subjects. The modestly increased relative risk was mainly driven by the subgroup of survivors who received HSCT and/or had a relapse. Our findings are reassuring for the large subgroup of ALL survivors without HSCT or relapse, and provide novel insight on both absolute and relative risk of hospital contacts for psychiatric disorders., (© 2024 The Author(s). Pediatric Blood & Cancer published by Wiley Periodicals LLC.)

Abstract: Primary hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disorder associated with autosomal recessive variants in genes required for perforin-mediated lymphocyte cytotoxicity. A rapid diagnosis is crucial for successful treatment. Although defective cytotoxic T lymphocyte (CTL) function causes pathogenesis, quantification of natural killer (NK)-cell exocytosis triggered by K562 target cells currently represents a standard diagnostic procedure for primary HLH. We have prospectively evaluated different lymphocyte exocytosis assays in 213 patients referred for evaluation for suspected HLH and related hyperinflammatory syndromes. A total of 138 patients received a molecular diagnosis consistent with primary HLH. Assessment of Fc receptor-triggered NK-cell and T-cell receptor (TCR)-triggered CTL exocytosis displayed higher sensitivity and improved specificity for the diagnosis of primary HLH than routine K562 cell-based assays, with these assays combined providing a sensitivity of 100% and specificity of 98.3%. By comparison, NK-cell exocytosis after K562 target cell stimulation displayed a higher interindividual variability, in part explained by differences in NK-cell differentiation or large functional reductions after shipment. We thus recommend combined analysis of TCR-triggered CTL and Fc receptor-triggered NK-cell exocytosis for the diagnosis of patients with suspected familial HLH or atypical manifestations of congenital defects in lymphocyte exocytosis., (Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution.)

Abstract: HLA-mismatched transplants with either in vitro depletion of CD3+ T-cell receptor (TCR)αβ/CD19 (TCRαβ) cells or in vivo T-cell depletion using posttransplant cyclophosphamide (PTCY) have been increasingly used for patients with inborn errors of immunity (IEIs). We performed a retrospective multicenter study via the EBMT registry on 306 children with IEIs undergoing their first transplant between 2010 and 2019 from an HLA-mismatched donor using TCRαβ (n = 167) or PTCY (n = 139). The median age for hematopoietic stem cell transplantation (HSCT) was 1.2 years (range, 0.03-19.6 years). The 3-year overall survival (OS) was 78% (95% confidence interval (CI), 71-84) after TCRαβ and 66% (57-74) after PTCY (P = .013). Pre-HSCT morbidity score (hazard ratio [HR], 2.27; 1.07-4.80, P = .032) and non-busulfan/treosulfan conditioning (HR, 3.12; 1.98-4.92, P < .001) were the only independent predictors of unfavorable OS. The 3-year event-free survival (EFS) was 58% (50%-66%) after TCRαβ and 57% (48%-66%) after PTCY (P = .804). The cumulative incidence of severe acute graft-versus-host disease (GvHD) was higher after PTCY (15%, 9%-21%) than TCRαβ (6%, 2%-9%, P = .007), with no difference in chronic GvHD (PTCY, 11%, 6%-17%; TCRαβ, 7%, 3%-11%, P = .173). The 3-year GvHD-free EFS was 53% (44%-61%) after TCRαβ and 41% (32%-50%) after PTCY (P = .080). PTCY had significantly higher rates of veno-occlusive disease (14.4% vs TCRαβ 4.9%, P = .009), acute kidney injury (12.7% vs 4.6%, P = .032), and pulmonary complications (38.2% vs 24.1%, P = .017). Adenoviremia (18.3% vs PTCY 8.0%, P = .015), primary graft failure (10% vs 5%, P = .048), and second HSCT (17.4% vs 7.9%, P = .023) were significantly higher in TCRαβ. In conclusion, this study demonstrates that both approaches are suitable options in patients with IEIs, although they are characterized by different advantages and outcomes., (© 2024 American Society of Hematology. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Pediatric hematopoietic stem cell transplantation (HSCT) is challenged by chronic graft-versus-host disease (cGvHD) significantly affecting survival and long-term morbidity, but underlying mechanisms including the impact of post-HSCT CMV infection are sparsely studied. We first investigated the impact of CMV infection for development of cGvHD in 322 children undergoing standard myeloablative HSCT between 2000 and 2018. Clinically significant CMV infection (n = 61) was an independent risk factor for chronic GvHD in a multivariable Cox regression analysis (HR = 2.17, 95% CI = 1.18-3.97, P = 0.013). We next explored the underlying mechanisms in a subcohort of 39 children. CMV infection was followed by reduced concentration of recent thymic emigrants (17.5 vs. 51.9 × 10 6 /L, P = 0.048) and naïve CD4+ and CD8+ T cells at 6 months post-HSCT (all P < 0.05). Furthermore, CD25 high FOXP3+ Tregs tended to be lower in patients with CMV infection (2.9 vs. 9.6 × 10 6 /L, P = 0.055), including Tregs expressing the naivety markers CD45RA and Helios. CD8+ T-cell numbers rose after CMV infection and was dominated by exhausted PD1-expressing cells (66% vs. 39%, P = 0.023). These findings indicate that post-HSCT CMV infection is a main risk factor for development of chronic GvHD after pediatric HSCT and suggest that this effect is caused by reduced thymic function with a persistently impaired production of naïve and regulatory T cells in combination with increased peripheral T-cell exhaustion., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2024. Published by Elsevier Inc.)

In children with acute myeloid leukemia (AML) who lack a human leukocyte antigen (HLA) identical sibling, the donor can be replaced with an HLA-matched unrelated donor (MUD) or a haploidentical donor (haplo). We compared outcomes of patients <18 years with AML in first and second complete remission (CR1 and CR2) undergoing a hematopoietic stem cell transplantation (HCT) either with a MUD with anti-thymocyte globulin (ATG) (N=420) or a haplo HCT with post-transplant cyclophosphamide (PT-CY) (N=96) after a myeloablative conditioning regimen (MAC) between 2011 and 2021, reported to the European Society for Blood and Marrow Transplantation. A matched pair analysis was performed to adjust for differences among groups. The final analysis was performed on 253 MUD and 95 haplo-HCT. In the matched cohort, median age at HCT was 11.2 and 10 years and median year of HCT was 2017 and 2018, in MUD and haplo-HCT recipients, respectively. The risk of grade III-IV acute graft-versus-host disease (aGVHD) was significantly higher in the haplo group (hazard ratio [HR]=2.33, 95% confidence interval [CI]: 1.18-4.58; P=0.01). No significant differences were found in 2 years overall survival (OS; 78.4% vs. 71.5%; HR=1.39, 95% CI: 0.84-2.31; P=0.19), leukemia-free survival (LFS; 72.7% vs. 69.5%; HR=1.22, 95% CI: 0.76-1.95; P=0.41), CI of relapse (RI; 19.3% vs. 19.5%; HR=1.14, 95% CI: 0.62-2.08; P=0.68) non-relapse-mortality (NRM; 8% vs. 11%; HR=1.39, 95% CI: 0.66-2.93; P=0.39) and graft-versus-host free relapse-free survival (GRFS; 60.7% vs. 54.5%, HR=1.38, 95% CI: 0.95-2.02; P=0.09) after MUD and haplo-HCT respectively. Our study suggests that haplo-HCT with PT-CY is a suitable option to transplant children with AML lacking a matched related donor.

This prospective multicentre trial evaluated the safety and the efficacy of a thiotepa/melphalan-based reduced intensity conditioning (RIC) haematopoietic stem cell transplantation (HSCT) in children and adolescents with chronic myeloid leukaemia (CML) in chronic phase (CP). Thirty-two patients were transplanted from matched siblings or matched unrelated donors. In 22 patients, HSCT was performed due to insufficient molecular response or loss of response to first- or second-generation tyrosine kinase inhibitor (TKI), with pretransplant BCR::ABL1 transcripts ranging between 0.001% and 33%. The protocol included a BCR::ABL1-guided intervention with TKI retreatment in the first year and donor lymphocyte infusions (DLI) in the second-year post-transplant. All patients engrafted. The 1-year transplant-related mortality was 3% (confidence interval [CI]: 0%-6%). After a median follow-up of 6.3 years, 5-year overall survival and event-free survival are 97% (CI: 93%-100%) and 91% (CI: 79%-100%) respectively. The current 5-year leukaemia-free survival with BCR::ABL1 <0.01% is 97% (CI: 88%-100%) and the current TKI- and DLI-free survival is 95% (CI: 85%-100%). The incidence of chronic graft-versus-host disease (GvHD) was 32%, being severe in four patients (13%). At last follow-up, 31 patients are GvHD-free and have stopped immunosuppression. RIC HSCT following pretreatment with TKI is feasible and effective in children and adolescents with CP-CML with an excellent disease-free and TKI-free survival., (© 2024 The Author(s). British Journal of Haematology published by British Society for Haematology and John Wiley & Sons Ltd.)

Abstract: Primary hemophagocytic lymphohistiocytosis (pHLH) is a life-threatening hyperinflammatory syndrome that develops mainly in patients with genetic disorders of lymphocyte cytotoxicity and X-linked lymphoproliferative syndromes. Previous studies with etoposide-based treatment followed by hematopoetic stem cell transplantation (HSCT) resulted in 5-year survival of 50% to 59%. Contemporary data are lacking. We evaluated 88 patients with pHLH documented in the international HLH registry from 2016-2021. In 12 of 88 patients, diagnosis was made without HLH activity, based on siblings or albinism. Major HLH-directed drugs (etoposide, antithymocyte globulin, alemtuzumab, emapalumab, ruxolitinib) were administered to 66 of 76 patients who were symptomatic (86% first-line etoposide); 16 of 57 patients treated with etoposide and 3 of 9 with other first-line treatment received salvage therapy. HSCT was performed in 75 patients; 7 patients died before HSCT. Three-year probability of survival (pSU) was 82% (confidence interval [CI], 72%-88%) for the entire cohort and 77% (CI, 64%-86%) for patients receiving first-line etoposide. Compared with the HLH-2004 study, both pre-HSCT and post-HSCT survival of patients receiving first-line etoposide improved, 83% to 91% and 70% to 88%. Differences to HLH-2004 included preferential use of reduced-toxicity conditioning and reduced time from diagnosis to HSCT (from 148 to 88 days). Three-year pSU was lower with haploidentical (4 of 9 patients [44%]) than with other donors (62 of 66 [94%]; P < .001). Importantly, early HSCT for patients who were asymptomatic resulted in 100% survival, emphasizing the potential benefit of newborn screening. This contemporary standard-of-care study of patients with pHLH reveals that first-line etoposide-based therapy is better than previously reported, providing a benchmark for novel treatment regimes., (© 2024 American Society of Hematology. Published by Elsevier Inc. All rights are reserved, including those for text and data mining, AI training, and similar technologies.)

Background: Allogeneic hematopoietic stem cell transplantation (HSCT) is challenged by acute non-infectious toxicities, including sinusoidal obstruction syndrome (SOS), engraftment syndrome (ES) and capillary leak syndrome (CLS) among others. These complications are thought to be driven by a dysfunctional vascular endothelium, but the pathophysiological mechanisms remain incompletely understood, and the diagnoses are challenged by purely clinical diagnostic criteria that are partly overlapping, limiting the possibilities for progress in this field. There is, however, increasing evidence suggesting that these challenges may be met through the development of diagnostic biomarkers to improve diagnostic accuracy of pathogenetically homogenous entities, improved pre-transplant risk assessment and the early identification of patients with increased need for specific treatment. Soluble vascular endothelial growth factor receptor-1 (sVEGF-R1) is emerging as an important biomarker of endothelial damage in patients with trauma and sepsis but has not been studied in HSCT., Objectives: To investigate sVEGF-R1 as a marker of endothelial damage in pediatric HSCT patients by exploring associations with SOS, CLS, ES, and acute graft-versus-host disease (aGvHD)., Methods: We prospectively included 113 children undergoing myeloablative HSCT and measured sVEGF-R1 in plasma samples obtained weekly during the early period of transplantation and 3 months post-transplant., Results: All over, sVEGF-R1 levels were significantly increased from day +7 after graft infusion, peaking at day +30, most pronounced in patients receiving busulfan. Patients considered to be at increased risk of SOS and therefore commenced on prophylactic defibrotide had significantly elevated levels of sVEGF-R1 before start of conditioning (446 pg/mL vs. 281 pg/mL, p = 0.0035), and this treatment appeared to stabilize sVEGF-R1 levels compared to patients not treated with defibrotide. Thirteen (11.5%) children meeting the modified Seattle criteria for SOS at median day +8 (1-18), had significantly elevated sVEGF-R1 levels on day +14 (489 pg/mL vs. 327 pg/mL, p = 0.007). In contrast. sVEGF-R1 levels in the much broader group of patients (45.1%) meeting EBMT-SOS criteria, including patients with very mild disease, did not overall differ in sVEGF-R1 levels, but higher sVEGF-R1 levels were seen in EBMT-SOS patients with an increased need for diuretic treatment. Importantly, sVEGF-R1 levels were not associated with ES and CLS but were significantly increased on day +30 in patients with grade III-IV aGvHD (OR = 4.2 pr. quartile, p = 0.023)., Conclusion: VEGF-R1 levels are found to be increased in pediatric patients developing SOS, reflecting the severity of morbidity. sVEGF-R1 were unassociated with both CLS and ES. The potential of sVEGF-R1 as a clinically useful biomarker for SOS should be further explored to improve pre-transplant SOS-risk assessment, SOS-severity grading, and to guide treatment., Competing Interests: Declaration of Competing Interest There are no conflicts of interests to declare., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Abstract: Allogeneic hematopoietic stem cell transplantation (HSCT) is highly effective for treating pediatric high-risk or relapsed acute lymphoblastic leukemia (ALL). For young children, total body irradiation (TBI) is associated with severe late sequelae. In the FORUM study (NCT01949129), we assessed safety, event-free survival (EFS), and overall survival (OS) of 2 TBI-free conditioning regimens in children aged <4 years with ALL. Patients received fludarabine (Flu), thiotepa (Thio), and either busulfan (Bu) or treosulfan (Treo) before HSCT. From 2013 to 2021, 191 children received transplantation and were observed for ≥6 months (median follow-up: 3 years). The 3-year OS was 0.63 (95% confidence interval [95% CI], 0.52-0.72) and 0.76 (95% CI, 0.64-0.84) for Flu/Thio/Bu and Flu/Thio/Treo (P = .075), respectively. Three-year EFS was 0.52 (95% CI, 0.41-0.61) and 0.51 (95% CI, 0.39-0.62), respectively (P = .794). Cumulative incidence of nonrelapse mortality (NRM) and relapse at 3 years were 0.06 (95% CI, 0.02-0.12) vs 0.03 (95% CI: <0.01-0.09) (P = .406) and 0.42 (95% CI, 0.31-0.52) vs 0.45 (95% CI, 0.34-0.56) (P = .920), respectively. Grade >1 acute graft-versus-host disease (GVHD) occurred in 29% of patients receiving Flu/Thio/Bu and 17% of those receiving Flu/Thio/Treo (P = .049), whereas grade 3/4 occurred in 10% and 9%, respectively (P = .813). The 3-year incidence of chronic GVHD was 0.07 (95% CI, 0.03-0.13) vs 0.05 (95% CI, 0.02-0.11), respectively (P = .518). In conclusion, both chemotherapeutic conditioning regimens were well tolerated and NRM was low. However, relapse was the major cause of treatment failure. This trial was registered at www.clinicaltrials.gov as #NCT01949129., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Background: Recovery and functional differentiation of T-cell subsets are central for the development of immune function and complications after allogeneic hematopoietic stem cell transplantation (HSCT), but little is known about the cellular respiration and factors influencing T-cell metabolic fitness during immune maturation after HSCT., Method: We included 20 HSCT patients and analysed mitochondrial oxidative phosphorylation and mitochondrial fitness in peripheral blood mononuclear cell samples collected at days +90 and +180 after HSCT., Results: Phenotypic analysis revealed lower overall T-cell counts, lower CD4+/CD8+ ratio and a skewed distribution of early T-cell subsets at day +90, gradually recovering by day +180. Although ATP turnover in HSCT patients was similar to healthy controls, the spare respiratory capacity (SRC) of T cells, reflecting the available energy reserve, was significantly reduced at day +90 and +180 compared to healthy controls. This reduction in SRC was not correlated with the occurrence of acute graft-versus-host disease (aGVHD), the intensity of conditioning regimens and markers of T-cell exhaustion., Conclusion: We found significantly depressed SRC until six months post-HSCT, but we were not able to identify transplant-related risk factors or associations with the clinical outcome., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Mølgaard, Kielsen, Ifversen, Met, Svane and Müller.)

Background: Metabolic syndrome (MetS) is frequent among survivors of childhood hematopoietic stem-cell transplantation (HSCT), but assessment of risk factors is challenged by survivor and participation bias in long-term follow-up studies., Methods: A cohort of 395 pediatric patients transplanted between 1980 and 2018 was investigated. MetS was assessed at follow-up between December 2018 and March 2020. Two composite outcomes ((a) combining MetS and death, (b) combining MetS, death, and nonparticipation) were considered to address the risk of selection bias., Results: Among 234 survivors invited to the follow-up, 96 individuals (median age 27 years) participated. MetS prevalence was 30% among participants. The only significant HSCT risk factor was a variable combining HSCT indication and conditioning with total-body irradiation (TBI) (p = .0011). Compared to acute leukemias (AL) treated with high-grade TBI (8-12 Gy), a lower MetS prevalence was seen for nonmalignant diseases treated with no/low-grade TBI (0-4.5 Gy) (OR = 0.04, 95% confidence interval (CI): 0.00-0.23). Analyses of the composite outcomes indicated overestimation of the effect of high-grade TBI due to selection bias. Scrutiny showed strong residual confounding between HSCT indication and high-grade TBI within AL-patients. The HSCT effect on MetS reflected HSCT effects on high-density-lipoprotein (HDL) and triglycerides. Compared to AL treated with high-grade TBI, nonmalignant diagnoses treated with no/low-grade TBI had higher HDL (+40%, 95% CI: +21% to +62%) and lower triglyceride (-59%, 95% CI: -71% to -42%)., Conclusion: The TBI effect on MetS may be overestimated in follow-up studies due to selection bias and confounding. The TBI effect was confined to the potentially modifiable MetS criteria  HDL and triglyceride., (© 2023 The Authors. Pediatric Transplantation published by Wiley Periodicals LLC.)

Risk factors for severe SARS-Cov-2 infection course are poorly described in children following hematopoietic cell transplantation (HCT). In this international study, we analyzed factors associated with a severe course (intensive care unit (ICU) admission and/or mortality) in post-HCT children. Eighty-nine children (58% male; median age 9 years (min-max 1-18)) who received an allogeneic (85; 96%) or an autologous (4; 4%) HCT were reported from 28 centers (18 countries). Median time from HCT to SARS-Cov-2 infection was 7 months (min-max 0-181). The most common clinical manifestations included fever (37; 42%) and cough (26; 29%); 37 (42%) were asymptomatic. Nine (10%) children following allo-HCT required ICU care. Seven children (8%) following allo-HCT, died at a median of 22 days after SARS-Cov-2 diagnosis. In a univariate analysis, the probability of a severe disease course was higher in allo-HCT children with chronic GVHD, non-malignant disease, immune suppressive treatment (specifically, mycophenolate), moderate immunodeficiency score, low Lansky score, fever, cough, coinfection, pulmonary radiological findings, and high C-reactive protein. In conclusion, SARS-Cov-2 infection in children following HCT was frequently asymptomatic. Despite this, 10% needed ICU admission and 8% died in our cohort. Certain HCT, underlying disease, and SARS-Cov-2 related factors were associated with a severe disease course., (© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)

Neutrophil engraftment is essential for the successful outcome after allogeneic hematopoietic stem cell transplantation (HSCT), but neutrophil activation may also induce transplant-related complications. Myeloid-related protein (MRP)-8/14 is expressed in granulocytes during inflammatory conditions and secreted in response to tissue damage along with the release of pro-inflammatory cytokines together with leukocyte recruitment and activation. In this study, we investigated associations between levels of the neutrophil activition marker MRP-8/14, neutrophil recovery and toxicities after pediatric HSCT. We included 73 children undergoing allogeneic HSCT using bone marrow or peripheral blood stem cell grafts from matched sibling or unrelated donors. Plasma levels of MRP-8/14 were measured by enzyme-linked immunosorbent assay from preconditioning until 6 months after transplantation. Overall, MRP-8/14 levels decreased from pre-conditioning to a nadir at day 7 and then rose again until day 28, preceding the reappearance of neutrophils. MRP-8/14 levels were significantly reduced at day 14 in patients with delayed neutrophil engraftment compared with patients who engrafted by day 21 (0.20 versus 0.48 μg/mL, P = .0012) and in patients who developed bacterial bloodstream infections compared to patients without this complication (0.2 versus 0.36 μg/mL, P = .048). Patients developing engraftment syndrome had significantly elevated MRP-8/14 levels at day 7 and 21 compared to patients without engraftment syndrome (0.32 versus 0.2 μg/mL, P = .042 and 1.9 versus 0.80 μg/mL, P = .039, respectively), as well as increased neutrophil counts from day 9 to 25 (P ≤ .016). Similarly, neutrophil counts were increased at day 13 to 17 in patients with acute graft-versus-host disease grade III-IV compared with grade 0-II. This study is the first to monitor neutrophil activation by MRP-8/14 in HSCT patients in relation to infectious, as well as noninfectious post-transplantation complications. Our results provide increased insights into the pathophysiology of these complications, and further studies should explore the potential use of MRP-8/14 as a clinically useful biomarker., (Copyright © 2023 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Male gonadal dysfunction is a frequent late effect after pediatric hematopoietic stem cell transplantation (HSCT) that can lead to disturbances in pubertal development, sexual dysfunction, and infertility. However, no systematic review exists regarding prevalence and risk factors in relation to different treatment regimens. We aimed to systematically evaluate the current evidence regarding the prevalence of male gonadal dysfunction after pediatric HSCT, related risk factors, and the diagnostic value of surrogate markers of spermatogenesis in this patient group. We searched PubMed and Embase using a combination of text words and subject terms. The eligibility screening was conducted using predefined criteria. Data were extracted corresponding to the Leydig cell compartment involved in testosterone production and the germ cell compartment involved in spermatogenesis, respectively. Subsequently, data synthesis was performed. Of 2369 identified records, 25 studies were eligible. The studies were heterogeneous in terms of included diagnoses, gonadotoxic therapy, follow-up time, and definitions of gonadal dysfunction. The data synthesis revealed a preserved Leydig cell function in patients treated with non-total body irradiation (TBI) regimens, whereas the evidence regarding the impact of TBI conditioning on Leydig cell function was conflicting. Based on surrogate markers of spermatogenesis and only limited data on semen quality, the germ cell compartment was affected in half of the patients treated with non-TBI regimens and in nearly all patients treated with TBI conditioning. Testicular irradiation as part of front-line therapy before referral to HSCT led to complete Leydig cell failure and germ cell failure. Evidence regarding the impact of diagnosis, pubertal stage at HSCT, and chronic graft-versus-host disease is limited, as is the evidence of the diagnostic value of surrogate markers of spermatogenesis. Testicular irradiation as part of front-line therapy and TBI conditioning are the main risk factors associated with male gonadal dysfunction after pediatric HSCT; however, impaired spermatogenesis is also observed in half of the patients treated with non-TBI regimens. Methodological shortcomings limit existing evidence, and future studies should include semen quality analyses, follow-up into late adulthood, and evaluation of the cumulative exposure to gonadotoxic therapy., Competing Interests: Conflict of interest statement There are no conflicts of interest to report., (Copyright © 2022 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

Purpose and Methods: To analyze physical fitness, physical activity and the prevalence of frailty in male long-term survivors of pediatric allogeneic hematopoietic stem cell transplantation (HSCT). We performed a Nordic two-center study of 98 male survivors (mean age 28.7 years, range 18.5-47.0) treated with pediatric allogeneic hematopoietic stem cell transplantation (HSCT) 1980-2010 in denmark or finland. physical fitness was evaluated by the dominant hand grip-strength, timed up-and-go, sit-to-stand, gait speed and two-minute walk tests., Results: Survivors presented significantly lower muscle strength and muscle endurance in the dominant hand-grip strength (median Z-score -0.7, range -4.3-3.9) and sit-to-stand tests (median Z-score -1.5, range -3.5-2.5) compared to age and sex matched normative values of the tests. However, mobility and gait speed were not affected on a group level. The prevalence of frailty (pre-frail 20% or frail 10%) was high among the survivors. In multiple regression analysis, chronic graft-versus-host disease, shorter stature, higher body fat mass and hazardous drinking predicted prefrail/frail status. Common cardiovascular risk factors, such as increased levels of serum triglycerides, higher resting heart rate and diastolic blood pressure, were associated with lower physical fitness., Conclusion: Low muscle strength and a high incidence of frailty were observed in survivors of pediatric HSCT. There is a predominant risk of cardiovascular and metabolic diseases in the long-term.

Allogeneic hematopoietic stem cell transplantation (HSCT) is a potentially curative treatment for patients affected by Wiskott-Aldrich syndrome (WAS). Reported HSCT outcomes have improved over time with respect to overall survival, but some studies have identified older age and HSCT from alternative donors as risk factors predicting poorer outcome. We analyzed 197 patients undergoing transplant at European Society for Blood and Marrow Transplantation centers between 2006 and 2017 who received conditioning as recommended by the Inborn Errors Working Party (IEWP): either busulfan (n = 103) or treosulfan (n = 94) combined with fludarabine ± thiotepa. After a median follow-up post-HSCT of 44.9 months, 176 patients were alive, resulting in a 3-year overall survival of 88.7% and chronic graft-versus-host disease (GVHD)-free survival (events include death, graft failure, and severe chronic GVHD) of 81.7%. Overall survival and chronic GVHD-free survival were not significantly affected by conditioning regimen (busulfan- vs treosulfan-based), donor type (matched sibling donor/matched family donor vs matched unrelated donor/mismatched unrelated donor vs mismatched family donor), or period of HSCT (2006-2013 vs 2014-2017). Patients aged <5 years at HSCT had a significantly better overall survival. The overall cumulative incidences of grade III to IV acute GVHD and extensive/moderate/severe chronic GVHD were 6.6% and 2.1%, respectively. Patients receiving treosulfan-based conditioning had a higher incidence of graft failure and mixed donor chimerism and more frequently underwent secondary procedures (second HSCT, unconditioned stem cell boost, donor lymphocyte infusion, or splenectomy). In summary, HSCT for WAS with conditioning regimens currently recommended by IEWP results in excellent survival and low rates of GVHD, regardless of donor or stem cell source, but age ≥5 years remains a risk factor for overall survival., (© 2022 by The American Society of Hematology.)

Background: Survivors of childhood acute lymphoblastic leukemia (ALL) may be at increased long-term risk of hospitalization for somatic diseases. However, large population-based cohort studies with risk estimates for survivors successfully cured without experiencing a relapse or requiring hematopoietic stem cell transplantation (HSCT) are lacking., Methods: Danish and Swedish patients diagnosed with ALL before age 20 years in 1982-2008 were identified in the national cancer registries. Five-year survivors and matched population comparisons without childhood cancer were followed for hospitalization for 120 somatic disease categories in the national hospital registries from 5 years postdiagnosis until 2017, and disease-specific hospitalization rate ratios (RR) were calculated. The mean cumulative count method was used to estimate the mean number of multiple and recurrent disease-specific hospitalizations per individual., Results: A total of 2024 5-year survivors and 9797 population comparisons were included. The overall hospitalization rate was more than twice as high compared with comparisons (RR = 2.30, 95% confidence interval [CI] = 2.09 to 2.52). At 30 years postdiagnosis, the mean cumulative hospitalization count was 1.69 (95% CI = 1.47 to 1.90) per survivor and 0.80 (95% CI = 0.73 to 0.86) per comparison. In the subcohort without relapse or HSCT (n = 1709), the RR was 1.41 (95% CI = 1.27 to 1.58)., Conclusions: Survivors of childhood ALL were at increased long-term risk for disease-specific hospitalizations; however, in survivors without relapse or HSCT, the rate was only modestly higher than in population comparisons without a childhood cancer. The absolute mean numbers of multiple and recurrent hospitalizations were generally low., (© The Author(s) 2022. Published by Oxford University Press.)

The ALL SCTped 2012 FORUM (For Omitting Radiation Under Majority age) trial compared outcomes for children ≥4 years of age transplanted for acute lymphoblastic leukaemia (ALL) who were randomised to myeloablation with a total body irradiation (TBI)-based or chemotherapy-based conditioning regimen. The TBI-based preparation was associated with a lower rate of relapse compared with chemoconditioning. Nevertheless, the age considered suitable for TBI was progressively raised over time to spare the most fragile youngest patients from irradiation-related complications. The best approach to use for children <4 years of age remains unclear. Children diagnosed with ALL in their first year of life, defined as infants, have a remarkably poorer prognosis compared with older children. This is largely explained by the biology of their ALL, with infants often carrying a KMT2A gene rearrangement, as well as by their fragility. In contrast, the clinical presentations and biological features of ALL in children >1 year but <4 years often resemble those presented by older children. In this review, we explore the state of the art regarding haematopoietic stem cell transplantation (HSCT) in children <4 years, the preparative regimens available, and new developments in the field that may influence treatment decisions., Competing Interests: JB has participated in advisory boards for Novartis, Janssen and Gilead, and speakers' bureaus for Novartis. AB has participated in advisory boards for Novartis and Amgen and speakers' bureau activities for Novartis, Amgen and Medac, and has received meeting support from Medac, Neovii and Novartis. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Balduzzi, Buechner, Ifversen, Dalle, Colita and Bierings.)

Despite advances in haematopoietic stem cell transplant (HSCT) techniques, the risk of serious side effects and complications still exists. Neurological complications, both acute and long term, are common following HSCT and contribute to significant morbidity and mortality. The aetiology of neurotoxicity includes infections and a wide variety of non-infectious causes such as drug toxicities, metabolic abnormalities, irradiation, vascular and immunologic events and the leukaemia itself. The majority of the literature on this subject is focussed on adults. The impact of the combination of neurotoxic drugs given before and during HSCT, radiotherapy and neurological complications on the developing and vulnerable paediatric and adolescent brain remains unclear. Moreover, the age-related sensitivity of the nervous system to toxic insults is still being investigated. In this article, we review current evidence regarding neurotoxicity following HSCT for acute lymphoblastic leukaemia in childhood. We focus on acute and long-term impacts. Understanding the aetiology and long-term sequelae of neurological complications in children is particularly important in the current era of immunotherapy for acute lymphoblastic leukaemia (such as chimeric antigen receptor T cells and bi-specific T-cell engager antibodies), which have well-known and common neurological side effects and may represent a future treatment modality for at least a fraction of HSCT-recipients., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The Reviewer GL declared a past collaboration with several of the authors, AL and MI, to the handling editor. The handling editor declared a shared consortium with the authors at time of review., (Copyright © 2021 Gabriel, Hoeben, Uhlving, Zajac-Spychala, Lawitschka, Bresters and Ifversen.)

Minimal residual disease (MRD) assessment plays a central role in risk stratification and treatment guidance in paediatric patients with acute lymphoblastic leukaemia (ALL). As such, MRD prior to haematopoietic stem cell transplantation (HSCT) is a major factor that is independently correlated with outcome. High burden of MRD is negatively correlated with post-transplant survival, as both the risk of leukaemia recurrence and non-relapse mortality increase with greater levels of MRD. Despite growing evidence supporting these findings, controversies still exist. In particular, it is still not clear whether multiparameter flow cytometry and real-time quantitative polymerase chain reaction, which is used to recognise immunoglobulin and T-cell receptor gene rearrangements, can be employed interchangeably. Moreover, the higher sensitivity in MRD quantification offered by next-generation sequencing techniques may further refine the ability to stratify transplant-associated risks. While MRD quantification from bone marrow prior to HSCT remains the state of the art, heavily pre-treated patients may benefit from additional staging, such as using 18 F-fluorodeoxyglucose positron emission tomography/computed tomography to detect focal residues of disease. Additionally, the timing of MRD detection (i.e., immediately before administration of the conditioning regimen or weeks before) is a matter of debate. Pre-transplant MRD negativity has previously been associated with superior outcomes; however, in the recent For Omitting Radiation Under Majority age (FORUM) study, pre-HSCT MRD positivity was associated with neither relapse risk nor survival. In this review, we discuss the level of MRD that may require pre-transplant therapy intensification, risking time delay and complications (as well as losing the window for HSCT if disease progression occurs), as opposed to an adapted post-transplant strategy to achieve long-term remission. Indeed, MRD monitoring may be a valuable tool to guide individualised treatment decisions, including tapering of immunosuppression, cellular therapies (such as donor lymphocyte infusions) or additional immunotherapy (such as bispecific T-cell engagers or chimeric antigen receptor T-cell therapy)., Competing Interests: JB has received personal fees, advisory board/steering committee honoraria, and nonfinancial support from Novartis; and advisory board honoraria from Pfizer, Kite, and Janssen. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Merli, Ifversen, Truong, Marquart, Buechner, Wölfl and Bader.)

Objectives: Longitudinal assessment of testicular function after pediatric hematopoietic stem cell transplantation (HSCT) is needed to guide clinical follow-up. We investigated dynamics in male reproductive hormones after pediatric HSCT, focusing on pubertal timing and associations with testosterone deficiency and azoospermia in adulthood., Methods: This retrospective, longitudinal study included 39 survivors median 19 years after pediatric HSCT. Serum concentrations of LH, testosterone, FSH, and inhibin B from the time of HSCT, during puberty, and into adulthood were analyzed. Pubertal timing (rise in LH and testosterone) was compared to a reference cohort of 112 healthy boys. Associations between reproductive hormone levels during puberty and adult testicular function (including semen quality) were investigated., Results: Pubertal induction with testosterone was needed in 6/26 patients who were prepubertal at HSCT. In the remaining patients, pubertal timing was comparable to the reference cohort. However, 9/33 patients (without pubertal induction) developed testosterone deficiency in early adulthood, which was associated with higher LH levels from age 14 to 16 years. Azoospermia in adulthood was found in 18/26 patients without testosterone substitution. Higher FSH and lower inhibin B levels from mid-pubertal age were associated with azoospermia in adulthood, in patients being prepubertal at HSCT., Conclusion: Our results indicate a substantial risk of deterioration in testicular function after pediatric HSCT, despite normal pubertal timing. Although reproductive hormone levels from mid-puberty indicated adult testicular function, prolonged follow-up into adulthood is needed in these patients, including clinical examination, reproductive hormone analysis, and semen sample for patients interested in their fertility potential.

Metabolic syndrome (MetS) is a growing concern in survivors of pediatric hematopoietic stem cell transplantation (HSCT), but little is known about the underlying mechanisms. This study aimed to determine the prevalence and clinical presentation of MetS in male long-term survivors of pediatric HSCT and to investigate predisposing factors, including low-grade inflammation, altered fat distribution, and low testosterone levels. We included 98 survivors age 19 to 47 years at a median follow-up of 18 years (range, 8 to 35 years) after pediatric HSCT. MetS was defined according to the National Cholesterol Education Program Adult Treatment Panel III criteria. The prevalence and clinical manifestations of MetS were compared between our cohort and a control group of males from the background population (n = 4767). Fat distribution was assessed by android/gynoid ratio from a whole-body dual-energy X-ray absorptiometry scan. Systemic inflammation was evaluated by IL-6 and high-sensitivity C-reactive protein (hsCRP). Serum testosterone levels were measured in morning samples. The prevalence of MetS was 30%, corresponding to the prevalence in the 50- to 80-year-old males from the background population. In individuals with MetS, hyperglycemia was more frequent in the HSCT survivors compared with age-matched controls with MetS (76% versus 20%; P < .001), whereas hypertension was more dominant in the control group with MetS (69% versus 93%; P = .01). In addition, normal or low body mass index was more commonly observed among HSCT survivors with MetS compared with age-matched controls with MetS (41% versus 11%; P = .002). MetS was more often associated with total body irradiation (TBI) compared with chemotherapy regimens (odds ratio [OR], 4.3; 95% confidence interval [CI], 1.2 to 24.4; P = .02), lower testosterone levels (OR, 5.4; 95% CI, 1.3 to 23.6; P = .02), higher IL-6 levels (OR, 1.8; 95% CI, 1.2 to 2.8; P = .004), and higher hsCRP levels (OR, 1.8; 95% CI, 1.3 to 2.6; P < .001) (estimates per 2-fold increase). In addition, an increased android/gynoid (AG) fat ratio was strongly associated with MetS (OR, 2.1; 95% CI, 1.5 to 2.9; P < .001), even though only 7% of patients met the criteria for increased abdominal circumference. Our results indicate an increased risk of MetS in early adulthood after pediatric HSCT. The clinical manifestations differed from those seen in age-matched controls with MetS, indicating different pathophysiology driven by hyperglycemia, altered fat distribution (despite no clinical abdominal obesity), and low-grade inflammation. Risk factors included TBI-based conditioning and low testosterone levels. These results underline the importance of continuous clinical assessment of the cardiometabolic risk profile and stress the presence of important dissimilarities in the pathophysiology of MetS in HSCT survivors compared with the background population., (Copyright © 2021 The American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

We aimed to assess short- and long-term mortality, including factors associated with mortality, for children referred to a pediatric intensive care unit (ICU) at Rigshospitalet, Denmark, following haematopoietic cell transplantation (HCT). Data regarding admission to ICU and mortality following HCT for children below 16 years of age between 2000 and 2017 were retrospectively analyzed. We identified 55 ICU admissions in 39 patients following 46 HCTs. The overall in-ICU, in-hospital, 3-month, and 1-year mortality rates were 33.3%, 43.6%, 46.2%, and 51.3%, respectively. Patients admitted from 2000 to 2010 had a 3-month mortality of 63.2% and 1-year mortality of 68.4%, compared to 30% and 35% (P = .040 and P = .039) for patients admitted from 2011 to 2017. The main reason for ICU admission was respiratory failure (78.2%). Mechanical ventilation (MV) was associated with a higher long-term mortality (P = .044), and use of inotropes or vasopressors was associated with increased mortality at all times (all P > .006). Extracorporeal life support, renal replacement therapy, longer ICU stay, and longer time with MV were not associated with increased mortality. Over the past two decades, mortality was significantly reduced in pediatric HCT patients admitted to the ICU. The cause is probably multifactorial and warrants further studies. Our findings support admissions of critically ill pediatric HCT patients to intensive care with encouraging outcomes of even long-term admissions., (© 2020 Wiley Periodicals LLC.)

Specific protocols define eligibility, conditioning, donor selection, graft composition and prophylaxis of graft vs. host disease for children and young adults undergoing hematopoietic stem cell transplant (HSCT). However, international protocols rarely, if ever, detail supportive care, including pharmaceutical infection prophylaxis, physical protection with face masks and cohort isolation or food restrictions. Supportive care suffers from a lack of scientific evidence and implementation of practices in the transplant centers brings extensive restrictions to the child's and family's daily life after HSCT. Therefore, the Board of the Pediatric Diseases Working Party (PDWP) of the European Society for Blood and Marrow Transplantation (EBMT) held a series of dedicated workshops since 2017 with the aim of initiating the production of a set of minimal recommendations. The present paper describes the consensus reached within the field of infection prophylaxis., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Ifversen, Meisel, Sedlacek, Kalwak, Sisinni, Hutt, Lehrnbecher, Balduzzi, Diesch, Jarisch, Güngör, Stein, Yaniv, Bonig, Kuhlen, Ansari, Nava, Dalle, Diaz-de-Heredia, Trigoso, Falkenberg, Hartmann, Deiana, Canesi, Broggi, Bertaina, Gibson, Krivan, Vettenranta, Matic, Buechner, Lawitschka, Peters, Yesilipek, Yalçin, Lucchini, Bakhtiar, Turkiewicz, Niinimäki, Wachowiak, Cesaro, Dalissier, Corbacioglu, Willasch and Bader.)

Background: Patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT) exhibit changes in their gut microbiota and are experiencing a range of complications, including acute graft-versus-host disease (aGvHD). It is unknown if, when, and under which conditions a re-establishment of microbial and immunological homeostasis occurs. It is also unclear whether microbiota long-term dynamics occur at other body sites than the gut such as the mouth or nose. Moreover, it is not known whether the patients' microbiota prior to HSCT holds clues to whether the patient would suffer from severe complications subsequent to HSCT. Here, we take a holobiont perspective and performed an integrated host-microbiota analysis of the gut, oral, and nasal microbiota in 29 children undergoing allo-HSCT., Results: The bacterial diversity decreased in the gut, nose, and mouth during the first month and reconstituted again 1-3 months after allo-HSCT. The microbial community composition traversed three phases over 1 year. Distinct taxa discriminated the microbiota temporally at all three body sides, including Enterococcus spp., Lactobacillus spp., and Blautia spp. in the gut. Of note, certain microbial taxa appeared already changed in the patients prior to allo-HSCT as compared with healthy children. Acute GvHD occurring after allo-HSCT could be predicted from the microbiota composition at all three body sites prior to HSCT. The reconstitution of CD4 + T cells, T H 17, and B cells was associated with distinct taxa of the gut, oral, and nasal microbiota., Conclusions: This study reveals for the first time bacteria in the mouth and nose that may predict aGvHD. Monitoring of the microbiota at different body sites in HSCT patients and particularly through involvement of samples prior to transplantation may be of prognostic value and could assist in guiding personalized treatment strategies. The identification of distinct bacteria that have a potential to predict post-transplant aGvHD might provide opportunities for an improved preventive clinical management, including a modulation of microbiomes. The host-microbiota associations shared between several body sites might also support an implementation of more feasible oral and nasal swab sampling-based analyses. Altogether, the findings suggest that the microbiota and host factors together could provide actionable information to guiding precision medicine. Video Abstract.

Differentially and functionally distinct T cell subsets are involved in the development of complications after allogeneic hematopoietic stem cell transplantation (HSCT), but little is known about factors regulating their recovery after HSCT. In this study, we investigated associations between immune-regulating cytokines, T cell differentiation, and clinical outcomes. We included 80 children undergoing allogeneic HSCT for acute leukemia using bone marrow or peripheral blood stem cells grafted from a matched sibling or unrelated donor. Cytokines (IL-7, IL-15, IL-18, SCF, IL-6, IL-2, and TNF-α) and active anti-thymocyte globulin (ATG) levels were longitudinally measured along with extended T cell phenotyping. The cytokine profiles showed a temporary rise in IL-7 and IL-15 during lymphopenia, which was strongly dependent on exposure to active ATG. High levels of IL-7 and IL-15 from graft infusion to day +30 were predictive of slower T cell recovery during the first 2 mo post-HSCT; however, because of a major expansion of memory T cell stages, only naive T cells remained decreased after 3 mo ( p < 0.05). No differential effect was seen on polarization of CD4 + T cells into Th1, Th2, or Th17 cells or regulatory T cells. Low levels of IL-7 and IL-15 at day +14 were associated with acute graft-versus-host disease grades II-IV in ATG-treated patients ( p = 0.0004 and p = 0.0002, respectively). Children with IL-7 levels comparable to healthy controls at day +14 post-HSCT were less likely to develop EBV reactivation posttransplant. These findings suggest that quantification of IL-7 and IL-15 may be useful as biomarkers in assessing the overall T cell depletion and suggest a potential for predicting complications after HSCT., (Copyright © 2021 by The American Association of Immunologists, Inc.)

The impact of conditioning regimen prior to hematopoietic cell transplant (HCT) in pediatric AML-patients is not well studied. We retrospectively analyzed the impact of Busulfan-Cyclophosphamide (BuCy), Busulfan-Cyclophosphamide-Melphalan (BuCyMel) and Clofarabine-Fludarabine-Busulfan (CloFluBu) in pediatric AML-patients, with similar upfront leukemia treatment (NOPHO-DBHconsortium), receiving an HCT between 2010 and 2015. Outcomes of interest were LFS, relapse, TRM and GvHD. 103 patients were included; 30 received BuCy, 37 BuCyMel, and 36 CloFluBu. The 5-years LFS was 43.3% (SE ± 9.0) in the BuCy group, 59.2 % (SE ± 8.1) after BuCyMel, and 66.7 % (SE ± 7.9) after CloFluBu. Multivariable Cox regression analysis showed a trend to lower LFS after BuCy compared to CloFluBu (p = 0.07). BuCy was associated with a higher relapse incidence compared to the other regimens (p = 0.06). Younger age was a predictor for relapse (p = 0.02). A strong correlation between Busulfan Therapeutic Drug Monitoring (TDM) and lower incidence of aGvHD (p < 0.001) was found. In conclusion, LFS after BuCyMel and CloFluBu was comparable, lower LFS was found after BuCy, due to higher relapse incidence. CloFluBu was associated with lower incidence of aGvHD, suggesting lower toxicity with this type of conditioning. This finding is also explained by the impact of Busulfan monitoring.

Changes in body composition related to metabolic syndrome are frequent among survivors of haematopoietic stem cell transplantation (HSCT), but insights into predisposing factors are incomplete, and it is unknown to what degree these changes persist at long term. We cross-sectionally investigated body composition by dual-energy X-ray absorptiometry in 98 male survivors of paediatric allogeneic HSCT. Median (range) age at follow-up was 28.1 (18.5-47.0) years and median (range) time from transplant was 18.3 (7.7-34.6) years. Lean Body Mass Index and Skeletal Muscle Mass Index were lower in patients compared to the reference population (mean (SD) standard deviation score (SDS) -1.29 (0.99), p < 0.001 and -1.20 (1.03), p < 0.001). Fat Mass Index was comparable to the reference population, but android/gynoid (AG) fat ratio SDS was higher (mean (SD) 0.46 (1.28), p < 0.001). These changes were found in patients treated with total body irradiation (TBI) as well as non-TBI regimens, although most pronounced in the former. Further, low lean mass was associated with chronic graft-versus-host disease, while high AG ratio was associated with lower testosterone levels. Since the combination of low lean mass and high AG ratio increases the risk of cardio-metabolic disease, these health issues should be monitored at long-term clinical follow-up after paediatric HSCT.

Purpose: Total body irradiation (TBI) before allogeneic hematopoietic stem cell transplantation (HSCT) in pediatric patients with acute lymphoblastic leukemia (ALL) is efficacious, but long-term side effects are concerning. We investigated whether preparative combination chemotherapy could replace TBI in such patients., Patients and Methods: FORUM is a randomized, controlled, open-label, international, multicenter, phase III, noninferiority study. Patients ≤ 18 years at diagnosis, 4-21 years at HSCT, in complete remission pre-HSCT, and with an HLA-compatible related or unrelated donor were randomly assigned to myeloablative conditioning with fractionated 12 Gy TBI and etoposide versus fludarabine, thiotepa, and either busulfan or treosulfan. The noninferiority margin was 8%. With 1,000 patients randomly assigned in 5 years, 2-year minimum follow-up, and one-sided alpha of 5%, 80% power was calculated. A futility stopping rule would halt random assignment if chemoconditioning was significantly inferior to TBI (EudraCT: 2012-003032-22; ClinicalTrials.gov: NCT01949129)., Results: Between April 2013 and December 2018, 543 patients were screened, 417 were randomly assigned, 212 received TBI, and 201 received chemoconditioning. The stopping rule was applied on March 31, 2019. The median follow-up was 2.1 years. In the intention-to-treat population, 2-year overall survival (OS) was significantly higher following TBI (0.91; 95% CI, 0.86 to 0.95; P < .0001) versus chemoconditioning (0.75; 95% CI, 0.67 to 0.81). Two-year cumulative incidence of relapse and treatment-related mortality were 0.12 (95% CI, 0.08 to 0.17; P < .0001) and 0.02 (95% CI, < 0.01 to 0.05; P = .0269) following TBI and 0.33 (95% CI, 0.25 to 0.40) and 0.09 (95% CI, 0.05 to 0.14) following chemoconditioning, respectively., Conclusion: Improved OS and lower relapse risk were observed following TBI plus etoposide compared with chemoconditioning. We therefore recommend TBI plus etoposide for patients > 4 years old with high-risk ALL undergoing allogeneic HSCT.

Type I and III leukocyte adhesion deficiencies (LADs) are primary immunodeficiency disorders resulting in early death due to infections and additional bleeding tendency in LAD-III. The curative treatment of LAD-I and LAD-III is allogeneic hematopoietic stem cell transplantation (allo-HSCT). In this retrospective multicenter study, data were collected using the European Society for Blood and Marrow Transplantation registry; we analyzed data from 84 LAD patients from 33 centers, all receiving an allo-HSCT from 2007 to 2017. The 3-year overall survival estimate (95% confidence interval [CI]) was 83% (74-92) for the entire cohort: 84% (75-94) and 75% (50-100) for LAD-I and LAD-III, respectively. We observed cumulative incidences (95% CI) of graft failure (GF) at 3 years of 17% (9%-26%) and grade II to IV acute graft-versus-host disease (aGVHD) at 100 days of 24% (15%-34%). The estimate (95% CI) at 3 years for GF- and GVHD-II to IV-free survival as event-free survival (EFS) was 56% (46-69) for the entire cohort; 58% (46-72) and 56% (23-88) for LAD-I and LAD-III, respectively. Grade II to IV acute GVHD was a relevant risk factor for death (hazard ratio 3.6; 95% CI 1.4-9.1; P = .006). Patients' age at transplant ≥13 months, transplantation from a nonsibling donor, and any serological cytomegalovirus mismatch in donor-recipient pairs were significantly associated with severe acute GVHD and inferior EFS. The choice of busulfan- or treosulfan-based conditioning, type of GVHD prophylaxis, and serotherapy did not impact overall survival, EFS, or aGVHD. An intrinsic inflammatory component of LAD may contribute to inflammatory complications during allo-HSCT, thus providing the rationale for considering anti-inflammatory therapy pretreatment., (© 2021 by The American Society of Hematology.)

Allogeneic HSCT represents the only potentially curative treatment for very high risk (VHR) ALL. Two consecutive international prospective studies, ALL-SCT-(I)BFM 2003 and 2007 were conducted in 1150 pediatric patients. 569 presented with VHR disease leading to any kind of HSCT. All patients >2 year old were transplanted after TBI-based MAC. The median follow-up was 5 years. 463 patients were transplanted from matched donor (MD) and 106 from mismatched donor (MMD). 214 were in CR1. Stem cell source was unmanipulated BM for 330 patients, unmanipulated PBSC for 135, ex vivo T-cell depleted PBSC for 62 and cord-blood for 26. There were more advanced disease, more ex vivo T-cell depletion, and more chemotherapy based conditioning regimen for patients transplanted from MMD as compared to those transplanted from MSD or MD. Median follow up (reversed Kaplan Meier estimator) was 4.99 years, median follow up of survivals was 4.88, range (0.01-11.72) years. The 4-year CI of extensive cGvHD was 13 ± 2% and 17 ± 4% (p = NS) for the patients transplanted from MD and MMD, respectively. 4-year EFS was statistically better for patients transplanted from MD (60 ± 2% vs. 42 ± 5%, p < 0.001) for the whole cohort. This difference does not exist if considering separately patients treated in the most recent study. There was no difference in 4-year CI of relapse. The 4-year NRM was lower for patients transplanted from MD (9 ± 1% vs. 23 ± 4%, p < 0.001). In multivariate analysis, donor-type appears as a negative risk-factor for OS, EFS, and NRM. This paper demonstrates the impact of donor type on overall results of allogeneic stem cell transplantation for very-high risk pediatric acute lymphoblastic leukemia with worse results when using MMD stem cell source.

Up to 40% of donor-recipient pairs in SCT have some degree of ABO incompatibility, which may cause severe complications. The aim of this study was to describe available options and survey current practices by means of a questionnaire circulated within the EBMT Pediatric Diseases Working Party investigators. Major ABO incompatibility (donor's RBCs have antigens missing on the recipient's cell surface, towards which the recipient has circulating isohemagglutinins) requires most frequently an intervention in case of bone marrow grafts, as immediate or delayed hemolysis, delayed erythropoiesis and pure red cell aplasia may occur. RBC depletion from the graft (82%), recipient plasma-exchange (14%) were the most common practices, according to the survey. Graft manipulation is rarely needed in mobilized peripheral blood grafts. In case of minor incompatible grafts (donor has isohemagglutinins directed against recipient RBC antigens), isohemagglutinin depletion from the graft by plasma reduction/centrifugation may be considered, but acute tolerability of minor incompatible grafts is rarely an issue. According to the survey, minor ABO incompatibility was either managed by means of plasma removal from the graft, especially when isohemagglutinin titer was above a certain threshold, or led to no intervention at all (41%). Advantages and disadvantages of each method are discussed.

A 9-year-old girl was admitted to the paediatric intensive care unit with acute respiratory failure due to influenza. Nine months earlier, she presented with unexplained lymphoedema of the lower extremities and monocytopenia. She had a history of occasional finger warts and onychomycoses. During hospitalisation, the patient was diagnosed with Emberger syndrome caused by GATA2 deficiency. The admission was complicated by thromboses in the right hand, leading to amputation of multiple fingers. From then on, the patient has been in good recovery, the function of her right hand was improving and an allogeneic haematopoietic cell transplantation has now been successfully performed., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Chimerism analysis following hematopoietic stem cell transplantation (HSCT) for leukemia is routinely applied in parallel with quantification of minimal residual disease (MRD) to identify imminent relapse. In the past decades, new methods with a lower limit of detection compared to standard methods have been developed, so-called microchimerism analysis. Microchimerism analysis is fast, simple, applicable across pre-HSCT disease-type and can be applied on peripheral blood allowing frequent testing during follow-up. Monitoring of microchimerism in blood could replace repeated bone marrow analysis for MRD and allow earlier detection of imminent relapse or graft failure. Clinical studies in single center cohorts have shown conflicting but promising results. There is currently no consensus on the interpretation of microchimerism analysis and heterogeneity of studies remains a major obstacle for inter-study comparisons and meta-analysis in this field. We have conducted a systematic review of studies investigating associations between microchimerism and relapse of leukemia post-HSCT. We summarize current evidence and provide suggestions for future research., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Male gonadal dysfunction is a frequent late effect after pediatric hematopoietic stem cell transplantation (HSCT), but detailed insight into patterns of male gonadal function at long-term is limited by retrospective studies without semen sample data. In this study, we investigated the risk of azoospermia and testosterone deficiency, the diagnostic value of markers of spermatogenesis, and paternity at long-term follow-up after pediatric allogeneic HSCT. All male HSCT survivors age ≥18 years, transplanted in Denmark or Finland between 1980 and 2010, were invited to participate in this cross-sectional study. Examinations included a semen sample, measurements of reproductive hormones and testicular volume, and screening for chronic graft-versus-host disease (GVHD). Cumulative (pre-HSCT plus HSCT) treatment doses were calculated. Of 181 eligible patients, 98 participated, at a median 18 years (range, 8 to 35 years) after undergoing HSCT. Sperm was found in 30 patients, azoospermia in 42, and azoospermia during testosterone substitution in 24. A higher cumulative testicular irradiation dose was associated with increased risk of azoospermia and testosterone substitution (odds ratio [OR] per +1 Gy, 1.27; 95% confidence interval [CI], 1.14 to 1.46 [P < .001] and 1.21; 95% CI, 1.11 to 1.38 [P < .001], respectively). All patients treated with >12 Gy had azoospermia, and all but 1 patient treated with >16 Gy needed testosterone substitution. In patients treated with chemotherapy only (n = 23), a higher cumulative cyclophosphamide equivalent dose was associated with an increased risk of azoospermia (OR per +1 g/m 2 , 1.34; 95% CI, 1.01 to 2.15; P = .037). Prepubertal stage at HSCT was a risk factor for testosterone substitution (OR, 15.31; 95% CI, 2.39 to 315; P = .017), whereas chronic GVHD was unrelated to gonadal dysfunction. Inhibin B was the best surrogate marker of azoospermia (area under the curve, .91; 95% CI, .85 to .98; 90% sensitivity and 83% specificity) compared with follicle-stimulating hormone and testicular volume. Of 24 males who had attempted to conceive, 6 had fathered children. In conclusion, the risk of male gonadal dysfunction after pediatric HSCT is high and depends primarily on the cumulative testicular irradiation dose and pubertal stage at transplantation. Our findings support the need for fertility preservation before HSCT, as well as for prolonged follow-up of pediatric HSCT recipients into adulthood., (Copyright © 2020 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc. All rights reserved.)

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.

There are many known endocrine complications after allogeneic hematopoietic stem cell transplantation (HSCT) in childhood including increased risk of biochemical hypogonadism. However, little is known about sexuality in adulthood following childhood HSCT. In this multicenter study, sexual functions and possible risk factors were assessed comprehensively in two national cohorts (Finland and Denmark) of male adult survivors of childhood HSCT. Compared to a healthy control group ( n = 56), HSCT survivors ( n = 97) reported less sexual fantasies, poorer orgasms, lower sexual activity with a partner and reduced satisfaction with their sex life, even in the presence of normal erectile functions and a similar frequency of autoerotic acts. Of the HSCT survivors, 35% were cohabitating/married and 66% were sexually active. Risk factors for poorer self-reported sexual functions were partner status (not cohabitating with a partner), depressive symptoms, CNS and testicular irradiation. Sexual dysfunction increased by age in the HSCT group with a pace comparable to that of the control group. However, because of the lower baseline level of sexual functions in the HSCT group, they will reach the level of clinically significant dysfunction at a younger age. Hence, male survivors of childhood HSCT should be interviewed in detail about their sexual health beyond erectile functions.