ABSTRACT:Chronic graft-versus-host-disease (cGVHD) is the primary nonrelapse limitation to a successful hematopoietic cell transplantation and is largely treated as a single biological entity. We hypothesized that there exist different biological subtypes of cGVHD. Using the Applied Biomarkers of Late Effects of Childhood Cancer (ABLE) network database, which is derived from the largest pediatric cGVHD cohort worldwide, we applied clustering analysis to subtype patients with cGVHD from the ABLE1.0 and 2.0 studies (51 patients with cGVHD and 158 with non-cGVHD). We found 3 distinct cGVHD subtypes: cGVHD-1 was characterized by an effector memory T-cell, cytotoxic natural killer cell, and early precursor B-cell predominant pattern; cGVHD-2 was phosphatidylcholine, cytokine, and plasma cell predominant; and cGVHD-3 had more naïve CD4+ T cells and naïve regulatory T cells, had later onset, and was the only subtype with measurable T-cell receptor excision circles. We partially replicated these subtypes using metabolomic data from a separate pediatric cohort of the Children's Oncology Group trial ASCT0031 (33 patients with cGVHD and 39 with non-cGVHD). Furthermore, cGVHD-1 was associated with serotherapy (predominantly antithymocyte globulin) exposure, and cGVHD-3 was associated with receiving peripheral blood stem cells from donors, total body irradiation, and no previous acute GVHD. cGVHD-2 was associated with liver involvement and cGVHD-2 and -3 with de novo cGVHD. Overall, none of the subtypes were closely associated with organ involvement. Contrasting each subtype against patients with non-cGVHD, the 3 subtypes shared common markers, all of which were used in our previous cGVHD diagnostic classifier. These findings suggest the presence of distinct biological subtypes of cGVHD that may help guide therapeutic strategies.

The lack of immune tolerance after hematopoietic cell transplantation (HCT) can result in chronic graft-versus-host disease (cGvHD), which is the primary nonrelapse limitation of successful HCT. To date, immune tolerance has been considered a single biological entity, but we hypothesized that post-HCT immune tolerance could develop through multiple pathways. Using the ABLE network database, which comprises measurements of 75 cell populations, 10 cytokines and chemokines, lymphocyte population telomere length, KRECs and TRECs, and 132 metabolites from the largest pediatric cGvHD cohort (n = 241), we applied clustering analysis to patients with primary immune tolerance (PIT; no acute GvHD [aGvHD] or cGvHD) and patients with secondary immune tolerance (SIT; previous aGvHD and no cGvHD) to test whether subtypes could be identified. The evaluation of PIT identified 3 subtypes. PIT-1, associated with postpubertal age, lower thymic output, and increased ST2 compared to PIT-2 and PIT-3, is effector memory T cell-predominant. PIT-2, associated with prepubertal age, normal thymic output, increased B cell development, and longer lymphocyte telomeres, has a naïve T cell-predominant pattern. PIT-3, associated with postpuberty, higher thymic output, and malignancy, is dominated by increased PD1+ regulatory T cells and helper T cells and decreased long-chain acylcarnitine. We partially replicated these PIT subtypes using metabolomic data from a separate pediatric cohort of the Children’s Oncology Group trial ASCT0031 (n = 24 PIT patients). Previously resolved aGvHD had a minimal impact on the overall patterns of SIT-1 and SIT-2 compared to PIT-1 and PIT-2, except for time delays in the expansion of some immune cells. PIT-3 and SIT-3 were dominated by late increases in phosphatidylcholines (lysophosphatidylcholine precursors) and long-chain lysophosphatidylcholines (LYSOC20:4 and LYSOC16:2), respectively. This is the first time that distinct biological patterns of immune reconstitution after HCT are identified, which on validation and potentially could aid the development of future strategies for tolerance induction.

The National Institutes of Health Consensus criteria for chronic graft-versus-host disease (cGVHD) diagnosis can be challenging to apply in children, making pediatric cGVHD diagnosis difficult. We aimed to identify diagnostic pediatric cGVHD biomarkers that would complement the current clinical criteria and help differentiate cGVHD from non-cGVHD. The Applied Biomarkers of Late Effects of Childhood Cancer (ABLE) study, open at 27 transplant centers, prospectively evaluated 302 pediatric patients after hematopoietic cell transplant (234 evaluable). Forty-four patients developed cGVHD. Mixed and fixed effect regression analyses were performed on diagnostic cGVHD onset blood samples for cellular and plasma biomarkers, with individual markers declared relevant if they met 3 criteria: an effect ratio & GE;1.3 or & LE;0.75; an area under the curve (AUC) of & GE;0.60; and a P value <5.814 x 10-4 (Bonferroni correction) (mixed effect) or <.05 (fixed effect). To address the complexity of cGVHD diagnosis in children, we built a machine learning-based classifier that combined multiple cellular and plasma biomarkers with clinical factors. Decreases in regulatory natural killer cells, naive CD4 T helper cells, and naive regulatory T cells, and elevated levels of CXCL9, CXCL10, CXCL11, ST2, ICAM-1, and soluble CD13 (sCD13) characterize the onset of cGVHD. Evaluation of the time dependence revealed that sCD13, ST2, and ICAM-1 levels varied with the timing of cGVHD onset. The cGVHD diagnostic classifier achieved an AUC of 0.89, with a positive predictive value of 82% and a negative predictive value of 80% for diagnosing cGVHD. Our polyomic approach to building a diagnostic classifier could help improve the diagnosis of cGVHD in children but requires validation in future prospective studies. This trial was registered at www.clinicaltrials.gov as #NCT02067832.

Rationale: Imatinib is used in the treatment of Philadelphia chromosome positive (Ph+) leukemias and has been reported to have a direct effect on bone physiology. Presentation: To report on a child with Ph+ acute lymphoblastic leukemia who presented with bilateral flank pain and gross hematuria. Diagnosis: She was diagnosed with obstructive kidney stones 101 days after commencing daily oral imatinib. Stone analysis revealed the presence of calcium phosphate. Interventions and outcome: The patient passed the stones spontaneously with medical therapy that included the use of thiazide, allopurinol, and potassium citrate, but she required temporary insertion of a double-J stent to relieve an obstruction. Novel findings: Imatinib inhibits receptor tyrosine kinases and stimulates the flux of calcium from the extracellular fluid into bone, resulting in hypocalcemia with a compensatory rise in parathyroid hormone that may result in phosphaturia and the formation of calcium phosphate stones. Given that kidney stones are rare events in children, we believe that monitoring for kidney stone formation needs to be performed in children receiving imatinib.

Background: The COVID-19 pandemic has had a major impact on access to health care resources. Our objective was to estimate the impact of the COVID-19 pandemic on the incidence of childhood cancer in Canada. We also aimed to compare the proportion of patients who enrolled in clinical trials at diagnosis, presented with metastatic disease or had an early death during the first 9 months of the COVID-19 pandemic compared with previous years. Methods: We conducted an observational study that included children younger than 15 years with a new diagnosis of cancer between March 2016 and November 2020 at 1 of 17 Canadian pediatric oncology centres. Our primary outcome was the monthly age-standardized incidence rates (ASIRs) of cancers. We evaluated level and trend changes using interventional autoregressive integrated moving average models. Secondary outcomes were the proportion of patients who were enrolled in a clinical trial, who had metastatic or advanced disease and who died within 30 days. We compared the baseline and pandemic periods using rate ratios (RRs) and 95% confidence intervals (CIs). Results: Age-standardized incidence rates during COVID-19 quarters were 157.7, 164.6, and 148.0 per million, respectively, whereas quarterly baseline ASIRs ranged between 150.3 and 175.1 per million (incidence RR 0.93 [95% CI 0.78 to 1.12] to incidence RR 1.04 [95% CI 0.87 to 1.24]). We found no statistically significant level or slope changes between the projected and observed ASIRs for all new cancers (parameter estimate [β], level 4.98, 95% CI −15.1 to 25.04, p = 0.25), or when stratified by cancer type or by geographic area. Clinical trial enrolment rate was stable or increased during the pandemic compared with baseline (RR 1.22 [95% CI 0.70 to 2.13] to RR 1.71 [95% CI 1.01 to 2.89]). There was no difference in the proportion of patients with metastatic disease (RR 0.84 [95% CI 0.55 to 1.29] to RR 1.22 [0.84 to 1.79]), or who died within 30 days (RR 0.16 [95% CI 0.01 to 3.04] to RR 1.73 [95% CI 0.38 to 15.2]). Interpretation: We did not observe a statistically significant change in the incidence of childhood cancer, or in the proportion of children enrolling in a clinical trial, presenting with metastatic disease or who died early during the first 9 months of the COVID-19 pandemic, which suggests that access to health care in pediatric oncology was not reduced substantially in Canada.

Human graft-versus-host disease (GVHD) biology beyond 3 months after hematopoietic stem cell transplantation (HSCT) is complex. The Applied Biomarker in Late Effects of Childhood Cancer study (ABLE/PBMTC1202, NCT02067832) evaluated the immune profiles in chronic GVHD (cGVHD) and late acute GVHD (L-aGVHD). Peripheral blood immune cell and plasma markers were analyzed at day 100 post-HSCT and correlated with GVHD diagnosed according to the National Institutes of Health consensus criteria (NIH-CC) for cGVHD. Of 302 children enrolled, 241 were evaluable as L-aGVHD, cGVHD, active L-aGVHD or cGVHD, and no cGVHD/L-aGVHD. Significant marker differences, adjusted for major clinical factors, were defined as meeting all 3 criteria: receiver-operating characteristic area under the curve >= 0.60, P <= .05, and effect ratio >= 1.3 or <= 0.75. Patients with only distinctive features but determined as cGVHD by the adjudication committee (non-NIH-CC) had immune profiles similar to NIH-CC. Both cGVHD and L-aGVHD had decreased transitional B cells and increased cytolytic natural killer (NK) cells. cGVHD had additional abnormalities, with increased activated T cells, naive helper T (Th) and cytotoxic T cells, loss of CD56(bright) regulatory NK cells, and increased ST2 and soluble CD13. Active L-aGVHD before day 114 had additional abnormalities in naive Th, naive regulatory T (T-reg) cell populations, and cytokines, and active cGVHD had an increase in PD(-)1(-) and a decrease in PD-1(+) memory T-reg cells. Unsupervised analysis appeared to show a progression of immune abnormalities from no cGVHD/L-aGVHD to L-aGVHD, with the most complex pattern in cGVHD. Comprehensive immune profiling will allow us to better understand how to minimize L-aGVHD and cGVHD. Further confirmation in adult and pediatric cohorts is needed.

Introduction Indications for hematopoietic stem cell transplantation (HSCT) in pediatric acute myeloid leukemia (AML) are primarily dependent on risk stratification at diagnosis and relapse status. We sought to determine whether access to HSCT is influenced by regional and socioeconomic factors. Methods Children with newly diagnosed AML aged Overall, 568 children with newly diagnosed AML were included and 262 (46%) received HSCT. A greater proportion of patients, 103/157 (65.6%), underwent HSCT after first or subsequent relapse compared to 159/411 (38.7%) patients who underwent transplant before relapse. Among patients for whom HSCT would be considered before relapse, factors associated with higher odds of HSCT in a multivariable analysis were: poor versus good-risk cytogenetics (Odds ratio [OR]: 30.0, 95% confidence interval [CI]: 7.7-117.0), diagnosis during 2012-2015 versus 2001-2006 (OR: 3.2, 95% CI: 1.6-6.3), diagnosis in eastern Canada versus central Canada (OR: 3.7, 95% CI: 1.9-7.3), and age 10-14 years versus age < 1 year (OR: 5.4, 95% CI: 2.3-12.8). Among patients for whom HSCT would be considered after first relapse, higher odds of HSCT was associated with diagnosis at a HSCT center (OR: 2.1, 95% CI: 1.1-4.1). Conclusion Patients diagnosed at a HSCT performing center and patients from eastern Canada had higher odds of receiving HSCT. This may suggest preferential access to HSCT for certain patients.

Pediatric chronic graft-versus-host disease (cGvHD) contributes to poor quality of life and increased morbidity and mortality in long term survivors of hematopoietic stem cell transplant (HSCT). Given the insidious nature of cGvHD, diagnosing cGvHD in children according to the National Institutes of Health Consensus Criteria (NIH-CC) can be challenging, particularly in the early phase of disease development. Diagnostic cGvHD biomarkers could aid in diagnosis. The Applied Biomarkers of Late Effects / Pediatric Blood and Marrow Transplant Consortium (ABLE / PBMTC 1202) study was a prospective, multi-institution study at 27 pediatric HSCT centers that evaluated biomarkers of cGvHD. Detailed clinical evaluation of cGvHD, including central adjudication when necessary, occurred as per the NIH-CC. Of the 302 enrolled children, 233 were included in this diagnostic cGvHD biomarker analysis, including 43 with cGvHD and 190 non-cGVHD controls. Peripheral blood was drawn into a STRECK tube at the onset of cGvHD and before escalation of immune suppression, sent overnight to a central laboratory, and evaluated by flow cytometry. Five flow cytometric antibody panels consisting of 76 combinations of cell surface markers were used to delineate subpopulations of T, Regulatory T (Tregs, CD4+CD127LowCD25+), B, NK, and myeloid cells. We analyzed each marker in two ways. First, to control for normal post-HSCT immune reconstitution, we divided cGvHD subjects into early- (day 0-120), mid- (day 121-240), and late-onset (>day 240) and compared their marker values against non-cGVHD controls at day 100, 6-months, and 12-months, respectively, using fixed effect linear regression models. Second, we compared the marker values of all cGvHD subjects at diagnosis against the marker values of non-cGvHD controls at all three time points and used mixed effect linear regression models to account for within-subject correlations. A cellular subpopulation was considered a clinically relevant and potential diagnostic cGvHD biomarker if all 4 criteria were met: a) the effect ratio (mean marker value of cGvHD subjects over non-cGvHD controls) was ≥1.3 or ≤0.75, b) the p-value was ≤.05, c) the receiver-operating characteristic area under the curve was ≥0.60, and d) the marker was detected by both the mixed effect model and in the same direction across all measurement time points in the fixed effect models. Using these criteria, 8 cellular subpopulations arose as potential diagnostic biomarkers of pediatric cGvHD (Table). Key subsets identified in cGvHD patients included decreased proportions of naïve helper T cells (CD4+CD45RA+, PD1-CD4+CD45RA+, CCR7+CD4+CD45RA+, CD27+CD4+CD45RA+), decreased naïve and recently emigrated Tregs (CD31+CD45RA+, PD1-CD45RA+), and decreased non-cytolytic regulatory NK cells (CD56BrightCD335High, CD56BrightPerforinLow). CD4+ recent thymic emigrants (CD4+CD31+CD45RA+), markers of thymopoeisis, were also significantly decreased in cGvHD (p=0.01) but did not meet all the required biomarker criteria. Evaluation of specific subsets of pediatric cGvHD showed that CD21LowCD19+ B cells were lower in patients with pulmonary (n=12) compared to a mucocutaneous predominant phenotype (n=31) (p=0.048). Cases of progressive cGvHD (n=18), characterized by concurrent acute GvHD features (overlap syndrome), had decreased proportions of CD19 B cells, T3 transitional B cells (CD38LowCD10-) and mature naïve B cells (IgD+CD27-), decreased naïve helper T cells (CCR7+CD4+CD45RA+) and increased activated NK cells (CD56dimCD69+) (all p<0.05). No cellular subsets were associated with the number of organ systems involved with cGvHD or global cGvHD severity according to the NIH-CC. Using a well characterized cohort of pediatric patients with cGvHD, the ABLE / PBTMC 1202 study showed that a variety of subpopulations of naïve helper T cells, Tregs, and regulatory NK cells were associated with cGvHD. Additional B-cell markers were associated with progressive cGvHD in children. These data support alterations in thymopoeisis and decreases in regulatory T- and NK-cell populations underlying pediatric cGvHD. Future work includes the addition of non-cellular plasma markers into a clinically applicable diagnostic biomarker algorithm to aid clinicians in the accurate diagnosis of pediatric cGvHD, as well as further validation in the ABLE 2.0 / Pediatric Transplant Cellular Therapy Consortium 1901 study. Disclosures Wahlstrom: Pharmacyclics: Current Employment. Pulsipher:Mesoblast: Honoraria; Adaptive: Research Funding; Miltenyi: Honoraria, Research Funding; Bellicum: Honoraria; Jasper: Honoraria; Novartis: Honoraria.

Although lysine methylation is classically known to regulate histone function, its role in modulating antiviral restriction factor activity remains uncharacterized. Interferon-induced transmembrane protein 3 (IFITM3) was found monomethylated on its lysine 88 residue (IFITM3-K88me1) to reduce its antiviral activity, mediated by the lysine methyltransferase SET7. Vesicular stomatitis virus and influenza A virus infection increased IFITM3-K88me1 levels by promoting the interaction between IFITM3 and SET7, suggesting that this pathway could be hijacked to support infection; conversely, IFN-α reduced IFITM3-K88me1 levels. These findings may have important implications in the design of therapeutics targeting protein methylation against infectious diseases.

Access to hematopoietic stem cell transplantation (HSCT) in pediatric acute lymphoblastic leukemia (ALL) primarily depends on disease-related factors but may be influenced by social and economic determinants. We included all children aged < 15 years with newly diagnosed ALL in Canada between 2001 and 2018 using the Cancer in Young People in Canada national registry. We examined factors potentially associated with the likelihood of receiving HSCT using univariate and multivariable logistic regression models. A total of 3992 patients with newly diagnosed ALL were included. Three hundred twenty-five (8.1%) received an HSCT and formed the transplant cohort. In multivariable analysis factors independently associated with an increased odds of receiving HSCT were male sex (odds ratio [OR], 1.42; 95% confidence interval [CI], 1.05 to 1.93), initial WBC >= 50,000 x 10(9)/L (OR, 1.58; 95% CI, 1.09 to 2.28), mixed phenotype acute leukemia relative to B-precursor ALL (OR, 34.32; 95% CI, 16.64 to 70.79), T cell relative to B-precursor ALL (OR, 1.77; 95% CI, 1.07 to 2.91), unfavorable relative to standard cytogenetics (OR, 3.96; 95% CI, 2.56 to 6.12), and relapse before HSCT (OR, 32.77; 95%, 23.89 to 44.96). No association was found between race, neighborhood income quintile or region at diagnosis, and receipt of HSCT. Diagnosis at an HSCT treating center (OR, 1.51; 95% CI, 1.09 to 2.09) and residential distance from the ALL treating center (OR, 1.84 for >= 300 km compared with <100 km; 95% CI, 1.17 to 2.91) were associated with higher odds of receiving HSCT. In a publically funded healthcare system, children with ALL had equitable access to HSCT, which was largely governed by biologic disease-related factors. Patients diagnosed at an HSCT performing center and patients who live farthest away from their treatment center had higher odds of receiving HSCT, although the effect was small, possibly suggesting preferential referral to HSCT for some patients. (C) 2019 American Society for Blood and Marrow Transplantation.

Chronic graft-versus-host disease (cGVHD) and late acute graft-versus-host disease (L-aGVHD) are understudied complications of allogeneic hematopoietic stem cell transplantation in children. The National Institutes of Health Consensus Criteria (NIH-CC) were designed to improve the diagnostic accuracy of cGVHD and to better classify graft-versus-host disease (GVHD) syndromes but have not been validated in patients <18 years of age. The objectives of this prospective multi-institution study were to determine: (1) whether the NIH-CC could be used to diagnose pediatric cGVHD and whether the criteria operationalize well in a multi-institution study; (2) the frequency of cGVHD and L-aGVHD in children using the NIH-CC; and (3) the clinical features and risk factors for cGVHD and L-aGVHD using the NIH-CC. Twenty-seven transplant centers enrolled 302 patients <18 years of age before conditioning and prospectively followed them for 1 year posttransplant for development of cGVHD. Centers justified their cGVHD diagnosis according to the NIH-CC using central review and a study adjudication committee. A total of 28.2% of reported cGVHD cases was reclassified, usually as L-aGVHD, following study committee review. Similar incidence of cGVHD and L-aGVHD was found (21% and 24.7%, respectively). The most common organs involved with diagnostic or distinctive manifestations of cGVHD in children include the mouth, skin, eyes, and lungs. Importantly, the 2014 NIH-CC for bronchiolitis obliterans syndrome perform poorly in children. Past acute GVHD and peripheral blood grafts are major risk factors for cGVHD and L-aGVHD, with recipients ≥12 years of age being at risk for cGVHD. Applying the NIH-CC in pediatrics is feasible and reliable; however, further refinement of the criteria specifically for children is needed.

Among 235 children with acute myeloid leukemia, 17 experienced 19 perianal infections. Among 12 episodes with definite abscess, 75% were severely neutropenic. Sixteen diagnostic imaging evaluations were performed; diagnostic yield was similar between computerized tomography of pelvis (5 of 10) and ultrasound (3 of 5). Consistent management approaches to perianal infection should be developed.

Abstract Introduction Sub-cutaneous panniculitis T-cell lymphomas (SPTCL), a rare non-Hodgkin lymphoma, can be associated with hemophagocytic lymphohistiocytosis (HLH), a life-threatening activation of the immune system which adversely impacts survival. T-cell immunoglobulin mucin 3 (TIM-3) is a modulator of immune responses expressed on subgroups of T- and innate immune cells. In this work we describe the first germline variants associated with SPTCL, which are in the TIM-3 gene. Methods We sequenced 27 SPTCL cases to identify gene variants. We performed TIM-3 functional analysis on immune cells from patients and HEK293 cells engineered to overexpress wild-type or mutant TIM-3. Results We identified homozygous, germline, loss-of-function, missense variants in highly conserved residues of TIM-3, namely p.Y82C and p.I97M in about 60% (16/27) of SPTCL cases. These samples were drawn from cases series across 3 continents. Patients with bi-allelic TIM-3 mutations were younger at diagnosis, and several had life-threatening HLH and severe disease course. TIM-3 mutations show specific geographic distribution. Y82C TIM-3 mutations occur on a founder chromosome in patients with East-Asian and Polynesian ancestry, while I97M TIM-3 is observed in Caucasians. Both variants induce protein misfolding and cytoplasmic retention of TIM-3. Loss of TIM-3 membrane expression in TIM-3 mutants abrogates the PD-1/PDL-1 checkpoint and prevents the termination of a Th1-immune response. In HEK293 cells, mutant TIM-3 was not expressed on the cell surface. Defective TIM-3 expression leads to persistent immune activation with increased production of inflammatory cytokines including TNF-alpha and IL-1beta by innate immune cells. Conclusion Our findings highlight HLH/SPTCL as a new genetic entity where loss of the TIM-3 immune checkpoint is associated with T-cell infiltration of adipose tissue and inflammasome activation. This is the first causative germline defect identified in SPTCL. While our findings indicate that TIM-3-mutant HLH/SPTCL benefit from immunomodulation, therapeutic repression of the TIM-3 checkpoint could have serious adverse consequences. Disclosures Prince: Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen Cilag: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees.

Background: Our group and others (Greinix BBMT 2015) have shown that higher proportions of recent thymic emigrants (RTEs: CD4+CD45RA+CD31+) at d100 are a prognostic biomarker for chronic GvHD in adults. We sought to understand whether RTEs, as well as regulatory T cells (CD4+CD25+CD127Lo) that co-express naïve and recently emigrated markers (CD45RA+CD31+; Treg RTEs) were prognostic at d100 for pediatric cGvHD. Methods: Allo-HCT patients (<18yrs) with malignant and non-malignant diagnoses were enrolled before HCT and prospectively followed for cGvHD until 1-year post-HCT. Blood was analyzed by 8-color flow cytometry at d100 (+/- 14d) for prognostic cellular cGvHD biomarkers. Mean values are reported. Biomarkers were considered clinically significant if means were >1.5× or <0.7× the control and P < .05. Two hundred and twelve patients were enrolled before June 30, 2016: 144 were evaluable with 1-year follow up and 68 excluded for relapse, non-engraftment or early death. Of the evaluable patients, 37 (25.7%) developed NIH criteria cGvHD, 34 (23.6%) had late aGvHD but no cGvHD, and 73 (50.7%) had no cGvHD. The no cGvHD group included patients both with and without a past history aGvHD, as we found previous aGvHD had no impact on d100 RTE and Treg RTE percentages in the absence of cGvHD. Late aGvHD was evaluated as a separate group independent of the cGvHD group. Results: RTEs as a % of CD4 T cells were significantly lower at d100 in patients with cGvHD compared to no cGvHD, and were prognostic for the later development of cGvHD (Table 1). Similar relationships existed for Treg RTEs, being significantly lower in cGvHD compared to no cGvHD. To determine whether RTEs and Treg RTEs were prognostic for any form of GvHD after d100, a combined group of cGvHD and late aGvHD was created and compared to the no cGvHD group. Both RTEs and Treg RTEs were significantly lower at d100 compared to the no cGvHD group and were prognostic for the development of any form of GvHD after d100.Table 1Cell PopulationNo cGvHDcGvHD onlyP-value*(AUC)Late aGvHD onlyP-value*(AUC)cGvHD + Late aGVHDP-value*(AUC)RTEs (% of CD4 T cells)13.5%7.8%.007 (.64)9.4%.08 (NS)8.5%.009 (.62)Treg RTEs (% of Tregs)13.2%6.4%.002 (.67)9.1%.06 (NS)7.6%.004 (.62)AUC, Area under curve on receiver operator curve.*Compared to the no cGvHD group. Open table in a new tab AUC, Area under curve on receiver operator curve. *Compared to the no cGvHD group. Conclusions: In this multi-institution study, both RTEs and Treg RTEs at d100 were prognostic biomarkers for pediatric cGvHD, irrespective of a previous history of aGvHD before d100. Interestingly, both T cell populations were lower compared to the no cGvHD group, a finding that is opposite to what our group and others have observed in adults with cGvHD. In a combined analysis of both late aGvHD and cGvHD, lower RTEs and Treg RTEs were also prognostic for GvHD after d100. These data suggest that thymic function may play a larger role in the later development of GvHD post-HCT for children compared to adults.

Traditionally in hematopoietic stem cell transplant (HSCT), cyclosporine doses are individualized using cyclosporine trough concentrations (C0) while area under the concentration vs time curve (AUC) is used in solid organ transplant. AUC potentially has an important relationship with the development of acute graft-versus-host-disease (aGVHD). We conducted a prospective study to describe the relationship between severe (grade III-IV) aGVHD and cyclosporine AUC in pediatric HSCT recipients. Pediatric patients who underwent allogeneic myeloablative HSCT and scheduled to receive cyclosporine for aGVHD prophylaxis participated in this multicenter study. Cyclosporine doses were adjusted based on C0 according to each center's standard of care. Cyclosporine AUC was determined weekly until neutrophil engraftment or Day +42, whichever was later. Associations between severe aGVHD and cyclosporine AUC and other patient and treatment-related factors were evaluated. Of the 110 children enrolled, 97 were evaluable. Thirty-seven (38%) children developed aGVHD; 13 (13.4%) had severe aGVHD. On univariate analysis, there was no association between severe aGVHD and cyclosporine AUC at any time point before engraftment. Future research should focus on refinement of C0 targets for cyclosporine therapeutic drug monitoring in HSCT.

In the version of this article originally published, the main-text sentence "In three patients of European ancestry, we identified the germline variant encoding p.Ile97Met in TIM-3, which was homozygous in two (P12 and P13) and heterozygous in one (P15) in the germline but with no TIM-3 plasma membrane expression in the tumor" misstated the identifiers of the two homozygous individuals, which should have been P13 and P14. The error has been corrected in the HTML, PDF and print versions of the paper.

Background: Children with acute myeloid leukemia (AML) are at high risk of life-threatening bacterial and fungal infection. However, little is known about the prevalence or severity of adenovirus infection in this population. Objective was to describe the characteristics, treatments and outcomes of adenovirus infection in children with newly diagnosed AML. Methods: We performed a retrospective chart review based upon 2 multicenter cohort studies that focused on identifying risk factors for infection in children with AML. Inclusion criteria were patients with de novo AML who were ≤18 years of age at diagnosis with a clinical specimen positive for adenovirus. Results: Among the 235 patients with AML, 12 (5.1%) had positive adenovirus testing. The most common site of isolation was stool (n = 11, 91.6 %), and the most frequent symptom was diarrhea (n = 11, 91.6 %). Two patients received specific treatment for adenovirus, namely intravenous immunoglobulin only in 1 patient and both intravenous immunoglobulin and inhaled ribavirin in a second patient. In 11 patients, adenovirus resolved uneventfully without recurrence, including 10 that received no adenovirus-specific therapy. However, 1 patient developed sepsis syndrome in the setting of disseminated adenoviral infection and died from multiorgan failure. Conclusion: In children with AML, adenovirus infection was rare and typically not associated with severe disease, even without specific treatment. However, disseminated and fatal disease can occur in this population. Further investigations are needed to identify pediatric AML patients at particular risk for severe adenovirus infection and to determine optimal treatment approaches in these patients.