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Adult hematopoietic stem cell transplantation (HSCT) recipients are at a high risk of adverse outcomes after COVID-19. Although children have had better outcomes after COVID-19 compared to adults, data on risk factors and outcomes of COVID-19 among pediatric HSCT recipients are lacking. We describe outcomes of HSCT recipients who were ≤21 years of age at COVID-19 diagnosis and were reported to the Center for International Blood and Marrow Transplant Research between March 27, 2020, and May 7, 2021. The primary outcome was overall survival after COVID-19 diagnosis. We determined risk factors of COVID-19 as a secondary outcome in a subset of allogeneic HSCT recipients. A total of 167 pediatric HSCT recipients (135 allogeneic; 32 autologous HSCT recipients) were included. Median time from HSCT to COVID-19 was 15 months (interquartile range [IQR] 7-45) for allogeneic HSCT recipients and 16 months (IQR 6-59) for autologous HSCT recipients. Median follow-up from COVID-19 diagnosis was 53 days (range 1-270) and 37 days (1-179) for allogeneic and autologous HSCT recipients, respectively. Although COVID-19 was mild in 87% (n=146/167), 10% (n=16/167) of patients required supplemental oxygen or mechanical ventilation. The 45-day overall survival was 95% (95% confidence interval [CI], 90-99) and 90% (74-99) for allogeneic and autologous HSCT recipients, respectively. Cox regression analysis showed that patients with a hematopoietic cell transplant comorbidity index (HCT-CI) score of 1-2 were more likely to be diagnosed with COVID-19 (hazard ratio 1.95; 95% CI, 1.03-3.69, P=.042) compared to those with an HCT-CI of 0. Pediatric and early adolescent and young adult HSCT recipients with pre-HSCT comorbidities were more likely to be diagnosed with COVID-19. Overall mortality, albeit higher than the reported general population estimates, was lower when compared with previously published data focusing on adult HSCT recipients.

Social determinants of health, including poverty, contribute significantly to health outcomes in the United States; however, their impact on pediatric hematopoietic cell transplantation (HCT) outcomes is poorly understood. We aimed to identify the association between neighborhood poverty and HCT outcomes for pediatric allogeneic HCT recipients in the Center for International Blood and Marrow Transplant Research database. We assembled 2 pediatric cohorts undergoing first allogeneic HCT from 2006 to 2015 at age ≤18 years, including 2053 children with malignant disease and 1696 children with nonmalignant disease. Neighborhood poverty exposure was defined a priori per the US Census definition as living in a high-poverty ZIP code (≥20% of persons below 100% federal poverty level) and used as the primary predictor in all analyses. Our primary outcome was overall survival (OS), defined as the time from HCT until death resulting from any cause. Secondary outcomes included relapse and transplantation-related mortality (TRM) in malignant disease, acute and chronic graft-versus-host disease, and infection in the first 100 days post-HCT. Among children undergoing transplantation for nonmalignant disease, neighborhood poverty was not associated with any HCT outcome. Among children undergoing transplantation for malignant disease, neighborhood poverty conferred an increased risk of TRM but was not associated with inferior OS or any other transplantation outcome. Among children with malignant disease, a key secondary finding was that children with Medicaid insurance experienced inferior OS and increased TRM compared with those with private insurance. These data suggest opportunities for future investigation of the effects of household-level poverty exposure on HCT outcomes in pediatric malignant disease to inform care delivery interventions.

Allogeneic hematopoietic cell transplant (HCT) is often the only curative therapy for patients with nonmalignant diseases; however, many patients do not have an HLA-matched donor. Historically, poor survival has been seen after HLA-haploidentical HCT because of poor immune reconstitution, increased infections, graft-versus-host disease (GVHD), and graft failure. Encouraging results have been reported using a nonmyeloablative T cell–replete HLA-haploidentical transplant approach in patients with hematologic malignancies. Here we report the outcomes of 23 patients with various nonmalignant diseases using a similar approach. Patients received HLA-haploidentical bone marrow (n = 17) or granulocyte colony-stimulating factor–mobilized peripheral blood stem cell (n = 6) grafts after conditioning with cyclophosphamide 50 mg/kg, fludarabine 150 mg/m2, and 2 or 4 Gy total body irradiation. Postgrafting immunosuppression consisted of cyclophosphamide, mycophenolate mofetil, tacrolimus, ± sirolimus. Median patient age at HCT was 10.8 years. Day 100 transplant-related mortality (TRM) was 0%. Two patients died at later time points, 1 from intracranial hemorrhage/disseminated fungal infection in the setting of graft failure and 1 from infection/GVHD. The estimated probabilities of grades II to IV and III to IV acute GVHD at day 100 and 2-year National Institutes of Health consensus chronic GVHD were 78%, 26%, and 42%, respectively. With a median follow-up of 2.5 years, the 2-year overall and event-free rates of survival were 91% and 78%, respectively. These results are encouraging and demonstrate favorable disease-specific lineage engraftment with low TRM in patients with nonmalignant diseases using nonmyeloablative conditioning followed by T cell–replete HLA-haploidentical grafts. However, additional strategies are needed for GVHD prevention to make this a viable treatment approach for patients with nonmalignant diseases.

Studies of genetic blood disorders have advanced our understanding of the intrinsic regulation of hematopoiesis. However, such genetic studies have only yielded limited insights into how interactions between hematopoietic cells and their microenvironment are regulated. Here, we describe two affected siblings with infantile myelofibrosis and myeloproliferation that share a common de novo mutation in the Rho GTPase CDC42 (Chr1:22417990:C>T, p.R186C) due to paternal germline mosaicism. Functional studies using human cells and flies demonstrate that this CDC42 mutant has altered activity and thereby disrupts interactions between hematopoietic progenitors and key tissue microenvironmental factors. These findings suggest that further investigation of this and other related disorders may provide insights into how hematopoietic cell-microenvironment interactions play a role in human health and can be disrupted in disease. In addition, we suggest that deregulation of CDC42 may underlie more common blood disorders, such as primary myelofibrosis.

Isavuconazole, administered as the water-soluble prodrug isavuconazonium sulfate, is a new triazole agent used to treat invasive fungal infections. This phase 1 study evaluated the pharmacokinetics (PK), safety, and tolerability of isavuconazole in 46 immunocompromised pediatric patients, stratified by age (1 to 80% and >76% of simulated pediatric patients following i.v. or oral administration, respectively. Intravenous and oral administration of isavuconazonium sulfate at the studied dosage of 10 mg/kg was well tolerated and resulted in exposure in pediatric patients similar to that in adults. (This study has been registered at ClinicalTrials.gov under identifier NCT03241550).

Transfusion-dependent β-thalassemia (TDT) and sickle cell disease (SCD) are severe monogenic diseases with severe and potentially life-threatening manifestations. BCL11A is a transcription factor that represses γ-globin expression and fetal hemoglobin in erythroid cells. We performed electroporation of CD34+ hematopoietic stem and progenitor cells obtained from healthy donors, with CRISPR-Cas9 targeting the BCL11A erythroid-specific enhancer. Approximately 80% of the alleles at this locus were modified, with no evidence of off-target editing. After undergoing myeloablation, two patients - one with TDT and the other with SCD - received autologous CD34+ cells edited with CRISPR-Cas9 targeting the same BCL11A enhancer. More than a year later, both patients had high levels of allelic editing in bone marrow and blood, increases in fetal hemoglobin that were distributed pancellularly, transfusion independence, and (in the patient with SCD) elimination of vaso-occlusive episodes. (Funded by CRISPR Therapeutics and Vertex Pharmaceuticals; ClinicalTrials.gov numbers, NCT03655678 for CLIMB THAL-111 and NCT03745287 for CLIMB SCD-121.).

Survival for high-risk neuroblastoma patients is still suboptimal. Although stem cell transplantation (SCT) is used, there is no consensus as to which conditioning regimen has the greatest efficacy and fewest toxicities. We assessed the incidence of and risk for hepatic veno-occlusive disease (VOD) for neuroblastoma patients who underwent autologous SCT with busulfan and melphalan (BuMel) at eight centers following Children's Oncology Group (COG)-based induction chemotherapy. Data regarding the patients, SCT characteristics, busulfan steady-state concentrations, incidence of VOD, and survival were evaluated. VOD was defined using the modified Seattle criteria. Possible factors associated with VOD (age, busulfan-pharmacokinetic parameters, history of hepatic dysfunction, and day of neutrophil engraftment) were evaluated. Seventy five patients were included and 23 children (31%) developed VOD at a median of 19 days after SCT (range 14-27 days). VOD was the cause of death in 4 patients (5%). In a multivariable analysis, young age (OR 1.7 (95% CI: 1.16-2.56; p = 0.012)) and early day of neutrophil engraftment (OR 1.4 (95% CI: 1.08-2.14; p = 0.041) were associated with the development of VOD. Initial or cumulative busulfan steady-state concentration were not associated with VOD. We found that despite the use of intravenous busulfan with adjusted serum levels, the incidence of VOD remains high in pediatric neuroblastoma patients.

Relapse remains the major cause of mortality after hematopoietic cell transplantation (HCT) for pediatric acute leukemia. Previous research has suggested that reducing the intensity of calcineurin inhibitor-based graft-versus-host disease (GVHD) prophylaxis may be an effective strategy for abrogating the risk of relapse in pediatric patients undergoing matched sibling donor (MSD) HCT. We reasoned that the benefits of this strategy could be maximized by selectively applying it to those patients least likely to develop GVHD. We conducted a study of risk factors for GVHD, to risk-stratify patients based on age. Patients age18 years with leukemia who received myeloablative, T cell-replete MSD bone marrow transplantation and calcineurin inhibitor-based GVHD prophylaxis between 2000 and 2013 and were entered into the Center for International Blood and Marrow Transplant Research registry were included. The cumulative incidence of grade II-IV acute GVHD (aGVHD) was 19%, that of grade II-IV aGVHD 7%, and that of chronic GVHD (cGVHD) was 16%. Compared with age 13 to 18 years, age 2 to 12 years was associated with a lower risk of grade II-IV aGVHD (hazard ratio [HR], .42; 95% confidence interval [CI], .26 to .70; P = .0008), grade II-IV aGVHD (HR, .24; 95% CI, .10 to .56; P = .001), and cGVHD (HR, .32; 95% CI, .19 to .54; P .001). Compared with 2000-2004, the risk of grade II-IV aGVHD was lower in children undergoing transplantation in 2005-2008 (HR, .36; 95% CI, .20 to .65; P = .0007) and in 2009-2013 (HR, .24; 95% CI. .11 to .53; P = .0004). Similarly, the risk of grade III-IV aGVHD was lower in children undergoing transplantation in 2005-2008 (HR, .23; 95% CI, .08 to .65; P = .0056) and 2009-2013 (HR, .16; 95% CI, .04 to .67; P = .0126) compared with those doing so in 2000-2004. We conclude that aGVHD rates have decreased significantly over time, and that children age 2 to 12 years are at very low risk for aGVHD and cGVHD. These results should be validated in an independent analysis, because these patients with high-risk malignancies may be good candidates for trials of reduced GVHD prophylaxis.

Background The Covid-19 pandemic has profoundly disrupted healthcare operations for vulnerable transplant and cell therapy patients. The Sarah Cannon Blood Cancer Network (SCBCN) comprises six Healthcare Corporation of America hospitals that have been certified based upon defined metrics of infrastructure, staffing, processes and volume. The SCBCN actively coordinated a response by integrating information from the framework of federal, state, network, hospital and individual transplant programs. Dynamic standards were developed taking into account operational aspects (such as PPE conservation, staffing, isolation policy, etc.), external regulations, and input from professional societies in order to balance the needs for life-saving therapy while reducing the likelihood of adverse consequences. In this study, we describe the impact of the Covid-19 across our network on transplant and cell therapy activity as well as the outcomes of the patients who were treated. Methods Data was integrated from electronic health records and a center survey questionnaire. The period of observation (defined as Covid era) was from March 15, 2020 to June 15th, 2020 to allow sufficient time for analysis of early outcomes. Transplant and cell therapy data from the prior 12 months was used as a comparator. Results: Within the SCBCN there was a decrease in overall transplant and cell therapy activity in the Covid era. Autologous transplantation was mainly diminished, particularly in the first 2 months. There was no significant impact on allogeneic or CAR-T therapy volumes. For allogeneic transplantation, there was a modest reduction in marrow grafts (11% to 8%) and a significant increase in cryopreservation (16% to 79%, P Conclusions: We describe a deliberate and coordinated reduction in transplant and cell therapy activity across our network compared to the prior year. For those patients who were selectively transplanted during the Covid19 pandemic, outcomes were not impaired. Our analysis will be updated at the time of presentation with data covering the Covid era from July-Oct '20. Figure Disclosures Bachier: Sanofi: Speakers Bureau; AlloVir: Honoraria; CRISPR: Honoraria; Juno Therapeutics, a Bristol-Myers Squibb Company: Honoraria. Kambhampati:AbbVie: Other: Investigator in AbbVie-sponsored clinical trials.. McSweeney:Kite, a Gilead Company: Consultancy, Honoraria, Research Funding, Speakers Bureau; Fred Hutchinson: Patents & Royalties; Colorado Blood Cancer Institute: Current Employment. Ramakrishnan:Amgen: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Cigna: Honoraria. Safah:Verastem: Honoraria; Astellas: Speakers Bureau; Amgen: Honoraria; Janssen: Speakers Bureau.

Acute myeloid leukemia (AML) patients often undergo allogeneic hematopoietic cell transplantation (alloHCT) in first complete remission (CR). We examined the effect of depth of clinical response, including incomplete count recovery (CRi) and/or measurable residual disease (MRD), in patients from the Center for International Blood and Marrow Transplantation Research (CIBMTR) registry. We identified 2492 adult patients (1799 CR and 693 CRi) who underwent alloHCT between January 1, 2007 and December 31, 2015. The primary outcome was overall survival (OS). Multivariable analysis was performed to adjust for patient-, disease-, and transplant-related factors. Baseline characteristics were similar. Patients in CRi compared to those in CR had an increased likelihood of death (HR: 1.27; 95% confidence interval: 1.13-1.43). Compared to CR, CRi was significantly associated with increased non-relapse mortality (NRM), shorter disease-free survival (DFS), and a trend toward increased relapse. Detectable MRD was associated with shorter OS, shorter DFS, higher NRM, and increased relapse compared to absence of MRD. The deleterious effects of CRi and MRD were independent. In this large CIBMTR cohort, survival outcomes differ among AML patients based on depth of CR and presence of MRD at the time of alloHCT. Further studies should focus on optimizing post-alloHCT outcomes for patients with responses less than CR.

Background: BCL11A is a key transcription factor that suppresses the production of fetal hemoglobin (HbF) in red blood cells (RBCs), leading to the production of adult Hb (HbA). In diseases with hemoglobin production defects such as b-thalassemia, or in sickle cell disease (SCD), HbF upregulation could ameliorate anemia and reduce transfusion requirements, such as in β-thalassemia, or reduce clinical complications, including vaso-occlusive crises (VOCs), in SCD. To induce potentially curative levels of HbF in erythrocytes, we used the ex vivo CRISPR-Cas9-based gene-editing platform to edit the erythroid enhancer region of BCL11A in hematopoietic stem and progenitor cells (HSPCs), producing CTX001. Aims: CLIMB THAL-111 (NCT03655678) and CLIMB SCD-121 (NCT03745287) are multi-center, first-in-human studies of CTX001 for transfusion-dependent b-thalassemia (TDT) and SCD, respectively. Here, we present available safety and efficacy results from all patients with at least 3 months of follow-up from both studies as of July 2020. Methods: Patients (aged 18 to 35 years) with TDT receiving packed red blood cell (pRBC) transfusions of ≥100 mL/kg/year or ≥10 units/year in the previous 2 years, and those with severe SCD, defined as ≥2 VOCs/year requiring medical care in the previous 2 years, were eligible. Peripheral CD34+ HSPCs were collected by apheresis after mobilization with G-CSF (filgrastim) and plerixafor (for TDT) or plerixafor alone (SCD). The erythroid enhancer region of BCL11A was edited in CD34+ cells using a specific CRISPR guide RNA and Cas9 nuclease. Prior to CTX001 infusion on Day +1, patients received myeloablation with 4 days of busulfan. Patients were monitored for stem cell engraftment and hematopoietic recovery, adverse events, total Hb and HbF production, hemolysis, F-cells, pRBC transfusion requirements (TDT), and VOCs (SCD) during follow-up. Results: Data are presented for patients with TDT (N=5; RBC transfusion history range: 23.5 to 61 units/year; CTX001 post-infusion follow-up through Months 15, 6, 4, 4, and 3, respectively) and with SCD (N=2; 7 VOCs/year and 7.5 VOCs/year, respectively, annualized over 2 years prior to consent; CTX001 post-infusion follow-up through Months 12 and 3, respectively). In the patients with TDT, median neutrophil engraftment occurred on Day +32 (range: +27 to +36); median platelet engraftment occurred on Day +37 (range: +34 to +52). In the patients with SCD, neutrophil engraftment occurred on Day +30 and Day +22 and platelet engraftment occurred on Day +30 and Day +33, respectively. All patients demonstrated increases in total Hb and HbF over time (Figure). Patients with TDT ceased receiving pRBC transfusions soon after CTX001 infusion, with the last pRBC transfusion occurring between 0.9 and 1.9 months after CTX001 infusion. The first patient with TDT who received CTX001 has remained transfusion-free for over 15 months. Patients with SCD have had no VOCs since CTX001 infusion. The first SCD patient who received CTX001 has remained free of VOCs for over 1 year. In all 7 patients, the safety profile after CTX001 infusion was generally consistent with busulfan myeloablation. Four serious adverse events (SAEs) related or possibly related to CTX001 were reported in 1 patient with TDT: headache, haemophagocytic lymphohistiocytosis (HLH), acute respiratory distress syndrome, and idiopathic pneumonia syndrome. All 4 of these SAEs occurred in the context of HLH and were either resolved or clinically improving at the time of this analysis. No other CTX001-related SAEs were reported in the other patients with TDT or in any patients with SCD. Conclusions: These data demonstrate that CTX001, a first-in-human, CRISPR-Cas9-modified autologous HSPC product, has resulted in increases in HbF and total Hb in the first 7 patients infused. All patients infused with CTX001 demonstrated hematopoietic engraftment with a post-infusion safety profile generally consistent with myeloablation. All 5 patients with TDT have been transfusion-free since ~2 months after CTX001 infusion and the 2 patients with severe SCD have had no VOCs during follow-up after CTX001 infusion. These early data demonstrate that CTX001 is a potential functional cure for the treatment of TDT and SCD. Data will be updated for the presentation. Data from these ongoing studies were submitted on behalf of the CLIMB THAL-111 and CLIMB SCD-121 Investigators. Figure Disclosures Frangoul: Vertex Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Bobruff:CRISPR Therapeutics: Current Employment, Current equity holder in publicly-traded company. Cappellini:BMS: Honoraria; CRISPR Therapeutics, Novartis, Vifor Pharma: Membership on an entity's Board of Directors or advisory committees; Genzyme/Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees. Fernandez:CRISPR Therapeutics: Current Employment, Current equity holder in publicly-traded company. Grupp:Juno/BMS: Other; Cellectis: Other; TCR2: Other: SAB; Servier: Research Funding; Janssen/JnJ: Consultancy; CBMG: Consultancy; Humanigen: Consultancy; GlaxoSmithKline: Consultancy; Roche: Consultancy; CRISPR Therapeutics/Vertex Pharmaceuticals: Other; Allogene: Other; Kite/Gilead: Research Funding; Novartis: Consultancy, Other: SSC, Research Funding; Adaptimmune: Other: SAB; Jazz: Other: SSC. Handgretinger:Amgen: Honoraria. Ho:CRISPR Therapeutics: Current Employment, Current equity holder in publicly-traded company. Imren:Vertex Pharmaceuticals Incorporated: Current Employment, Current equity holder in publicly-traded company. Kattamis:Agios: Consultancy; Vertex: Membership on an entity's Board of Directors or advisory committees; Ionis: Membership on an entity's Board of Directors or advisory committees; Genesis Pharma SA: Membership on an entity's Board of Directors or advisory committees; Vifor: Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene/BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Apopharma/Chiesi: Honoraria, Speakers Bureau. Lekstrom-Himes:Vertex Pharmaceuticals Incorporated: Current Employment, Current equity holder in publicly-traded company. Locatelli:Medac: Speakers Bureau; Miltenyi: Speakers Bureau; Bellicum Pharmaceutical: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz Pharmaceeutical: Speakers Bureau. Lu:Vertex Pharmaceuticals Incorporated: Current Employment, Current equity holder in publicly-traded company. de Montalembert:Bluebird bio: Honoraria, Membership on an entity's Board of Directors or advisory committees; Vertex: 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; Addmedica: Honoraria, Membership on an entity's Board of Directors or advisory committees. Mulcahey:Vertex Pharmaceuticals Incorporated: Current Employment, Current equity holder in publicly-traded company. Shanbhag:Vertex Pharmaceuticals Incorporated: Current Employment, Current equity holder in publicly-traded company. Sheth:Agios: Consultancy, Research Funding; Celgene/BMS: Consultancy, Research Funding; La Jolla: Research Funding; Acceleron: Consultancy; Bluebird Bio: Consultancy; Novartis: Consultancy, Research Funding; DisperSol Technologies: Research Funding; Terumo: Research Funding; Vertex Pharmaceuticals/CRISPR Therapeutics: Membership on an entity's Board of Directors or advisory committees. Soni:CRISPR Therapeutics: Current Employment, Current equity holder in private company. Steinberg:Vertex Pharmaceuticals/CRISPR Therapeutics: Membership on an entity's Board of Directors or advisory committees; Fulcrum Therapeutics: Membership on an entity's Board of Directors or advisory committees; DSMB: Membership on an entity's Board of Directors or advisory committees; Imara: Membership on an entity's Board of Directors or advisory committees. Weinstein:CRISPR Therapeutics: Current Employment, Current equity holder in publicly-traded company. Wu:Bayer: Research Funding; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees; Octapharma: Membership on an entity's Board of Directors or advisory committees; CSL Behring: Membership on an entity's Board of Directors or advisory committees; Bioverativ: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees.

Allogeneic hematopoietic stem cell transplantation (alloHCT) may be associated with significant morbidity and mortality, resulting in increased healthcare utilization (HCU). To date, no multicenter comparative cost analyses have specifically evaluated alloHCT in children with acute leukemia. In this retrospective cohort study, we examined the relationship between survival and HCU while investigating the hypothesis that matched sibling donor (MSD) alloHCT has significantly lower inpatient HCU with unrelated donor (URD) alloHCT, and that among URDs, umbilical cord blood (UCB) alloHCT will have higher initial utilization but lower long-term utilization. Clinical and transplantation outcomes data from the Center for International Blood and Marrow Transplant Research (CIBMTR) were merged with inpatient cost data from the Pediatric Health Information System (PHIS) database using a probabilistic merge methodology. The merged dataset comprised US patients age 1 to 21 years who underwent alloHCT for acute leukemia between 2004 and 2011 with comprehensive CIBMTR data at a PHIS hospital. AlloHCT was analyzed by donor type, with specific analysis of utilization and costs using PHIS claims data. The primary outcomes of overall survival (OS), leukemia-free survival (LFS), and inpatient costs were evaluated using Kaplan-Meier curves and Cox and Poisson models. A total of 632 patients were identified in both the CIBMTR and PHIS data. The 5-year LFS was 60% for MSD alloHCT, 47% for well-matched matched unrelated donor bone marrow (MUD) alloHCT, 48% for mismatched unrelated donor alloHCT, and 45% for UCB alloHCT (P = .09). Total adjusted costs were significantly lower for MSD alloHCT versus MUD alloHCT by day 100 (adjusted cost ratio [ACR], .73; 95% confidence interval [CI], .62 to .86; P.001), and higher for UCB alloHCT versus MUD alloHCT (ACR, 1.27; 95% CI, 1.11 to 1.45; P.001). By 2 years, total adjusted costs remained significantly lower for MSD alloHCT compared with MUD alloHCT (ACR, .67; 95% CI, .56 to .81; P.001) and higher for UCB alloHCT compared with MUD alloHCT (ACR, 1.25; 95% CI, 1.02 to 1.52; P = .0280). Our data show that UCB and MUD alloHCT provide similar survival outcomes; however, MUD alloHCT has a significant advantage in cost by day 100 and 2 years. More research is needed to determine whether the cost difference among URD alloHCT approaches remains significant with a larger sample size and/or beyond 2 years post-alloHCT.

With modern therapy, overall survival (OS) for children with acute lymphoblastic leukemia approaches 90%. However, inferior outcomes for minority children have been reported. Data on the effects of ethnicity/race as it relates to socioeconomic status are limited. Using state cancer registry data from Texas and Florida, we evaluated the impact of neighborhood-level poverty rate and race/ethnicity on OS for 4719 children with acute lymphoblastic leukemia. On multivariable analysis, patients residing in neighborhoods with the highest poverty rate had a 1.8-fold increase in mortality compared with patients residing in neighborhoods with the lowest poverty rate (hazard ratio [HR], 1.8; 95% confidence interval [CI], 1.41-2.30). Hispanic and non-Hispanic black patients also had increased risk of mortality compared with non-Hispanic white patients (Hispanic: HR, 1.18; 95% CI, 1.01-1.39; non-Hispanic black: HR, 1.31; 95% CI, 1.03-1.66). On subgroup analysis, there was a 21.7% difference in 5-year OS when comparing non-Hispanic white children living in the lowest poverty neighborhoods (5-year OS, 91.2%; 95% CI, 88.6-93.2) to non-Hispanic black children living in the highest poverty neighborhoods (5-year OS, 69.5%; 95% CI, 61.5-76.1). To address such disparities in survival, further work is needed to identify barriers to cancer care in this pediatric population.

Allogeneic hematopoietic cell transplant is a potential curative therapy for acute lymphoblastic leukemia (ALL). Delineating the graft-versus-leukemia (GVL) effect as a function of graft-versus-host disease (GVHD) offers the potential to improve survival. We examined 5215 transplant recipients with ALL reported to the Center for International Blood and Marrow Transplant Research registry. Overall survival (OS) was compared according to the presence and severity of GVHD and evaluated in 3 cohorts: 2593 adults in first or second complete remission (CR1/CR2), 1619 pediatric patients in CR1/CR2, and 1003 patients with advanced (CR ≥3 or active disease) ALL. For patients in CR1/CR2, development of acute GVHD (aGVHD) or chronic GVHD (cGVHD) was associated with lower risk of relapse than no GVHD (hazard ratio [HR], 0.49-0.69). Patients with advanced ALL developing grades III and IV aGVHD or cGVHD were also at lower risk of relapse (HRs varied from 0.52 to 0.67). Importantly, adult and children in CR1/CR2 with grades I and II aGVHD without cGVHD experienced the best OS compared with no GVHD (reduction of mortality with HR, 0.83-0.76). Increased nonrelapse mortality accompanied grades III and IV aGVHD (HRs varied from 2.69 to 3.91) in all 3 cohorts and abrogated any protection from relapse, resulting in inferior OS. Patients with advanced ALL had better OS (reduction in mortality; HR, 0.69-0.73) when they developed cGVHD with or without grades I and II aGVHD. In conclusion, GVHD was associated with an increased GVL effect in ALL. GVL exerted a net beneficial effect on OS only if associated with low-grade aGVHD in CR1/CR2 or with cGVHD in advanced ALL.

Introduction Central venous catheter (CVC) access is an essential component of pediatric hematopoietic stem cell transplant (HSCT). Long-term CVC access is associated with an increased risk of infection and device dysfunction. Studies have shown that one in four CVC devices in the pediatric population require removal prior to completion of treatment due to infectious or mechanical complications. A retrospective analysis evaluated CVC-related complications in Hickman versus Proline catheters among pediatric HSCT recipients. Methods We performed a detailed retrospective chart review of CVC related complications among pediatric patients who underwent HSCT between June 2016 and October 2019. During the study period there was a change in the standard CVC access device from Hickman to Proline catheter. We compared the complications related to Hickman Catheter (Cohort 1) to Proline line (Cohort 2). All patients received antibacterial prophylaxis with cefepime. Results Thirty- two patients with a median age 7 years (range 0.75-19) underwent HSCT for malignant (N=16) or nonmalignant (N=16) disease. The majority underwent allogeneic HSCT (N=29). CVC complications requiring line removal occurred in 3 out of 15 (20%) HSCTs in Cohort 1 in comparison to 2 out of 18 (11%) in Cohort 2. Of the 3 complications in Cohort 1, 2 (66%) were related to infection and 1 (33%) due to device malfunction. Both line removals in Cohort 2 were due to device malfunction. There was one documented central line infection in Cohort 2 that did not require line removal. Conclusion Results of this small pilot study suggests that Proline catheters for long-term access in pediatric HSCT recipients may lead to a decrease incidence of complications requiring line removal in comparison Hickman catheters. Further research is indicated in order to provide recommendations for the optimal CVC for long-term access in pediatric HSCT.

BACKGROUND: Wilms tumor (WT) is the most common childhood kidney cancer worldwide, yet its incidence and clinical behavior vary according to race and access to adequate healthcare resources. In order to guide and streamline therapy in the war-torn and resource-constrained city of Baghdad, Iraq, we conducted a first-ever molecular analysis of 20 WT specimens to characterize the biological features of this lethal disease within this challenged population. METHODS: Next Generation Sequencing of 10 target genes associated with WT development and treatment resistance (WT1, CTNNB1, WTX, IGF2, CITED1, SIX2, p53, NMYC, CRABP2, and TOP2A) was completed. Immunohistochemistry was performed for 6 marker proteins of WT (WT1, CTNNB1, NCAM, CITED1, SIX2, and p53). Patient outcomes were compiled. RESULTS: Mutations were detected in previously described WT “hot spots” (e.g., WT1 and CTNNB1) as well as novel loci that may be unique to the Iraqi population. Immunohistochemistry showed expression domains most typical of blastemal-predominant WT. Remarkably, despite the challenges facing families and care providers, only one child, with combined WT1 and CTNNB1 mutations, was confirmed dead from disease. Median clinical follow-up was 40.5 months (range, 6 to 78 months). CONCLUSIONS: These data suggest that WT biology within a population of Iraqi children manifests features both similar to and unique from disease variants in other regions of the world. These observations will help to risk stratify WT patients living in this difficult environment to more or less intensive therapies and to focus treatment on cell-specific targets.

Background Plerixafor is used as an adjuvant to standard G-CSF mobilization to increases CD34+ cell mobilization and decreases the need for multiple days of collection. For patients with multiple myeloma (MM) and a collection goal of ≥5 × 10e6 CD34/kg our center follows an algorithm - if day 4 absolute CD34 is ≤20 cells/µl, patients are given a single dose of plerixafor in addition to G-CSF. For CD34 counts between 20 and 30/ µl, the administration of plerixafor was physician-dependent. Methods To assess the effectiveness of our algorithm we identified 119 consecutive MM patients who had GCSF only mobilization at our center and investigated the relationship between their day 4 absolute CD34, the administration of plerixafor and the number of days of apheresis. The patients were categorized into the following groups based upon day 4 CD34 count and administration of plerixafor (P): CD34 30 noP (n=26). Results In the 30noP group, 23/26 (88%) patients reached goal (range 4.01 × 106 – 9.14 × 106 CD34/kg) on day 1. Patients with Day 4 CD34 count between 20-30/ µl were significantly more likely to collect in one day if they have received Plerixafor (P=0.002). Conclusion This data justifies revision of the threshold for plerixafor administration to patients with a day 4, CD34 count from

Background Chronic nonhealing wounds are the norm in patients with inherited epidermolysis bullosa (EB), especially those with dystrophic EB (DEB). A possible benefit in wound healing after subcutaneous treatment with granulocyte colony-stimulating factor (G-CSF) was suggested from an anecdotal report of a patient given this during stem cell mobilization before bone-marrow transplantation. Objective We sought to determine whether benefit in wound healing in DEB skin might result after 6 daily doses of G-CSF and to confirm its safety. Methods Patients were assessed for changes in total body blister and erosion counts, surface areas of selected wounds, and specific symptomatology after treatment. Results Seven patients with DEB (recessive, 6; dominant, 1) were treated daily with subcutaneous G-CSF (10 μg/kg/dose) and reevaluated on day 7. For all patients combined, median reductions of 75.5% in lesional size and 36.6% in blister/erosion counts were observed. When only the 6 responders were considered, there were median reductions of 77.4% and 38.8% of each of these measured parameters, respectively. No adverse side effects were noted. Limitations Limitations include small patient number, more than 1 DEB subtype included, and lack of untreated age-matched control subjects. Conclusions Subcutaneous G-CSF may be beneficial in promoting wound healing in some patients with DEB when conventional therapies fail.

Busulfan combined with cyclophosphamide (BuCy) has long been considered a standard myeloablative conditioning regimen for allogeneic hematopoietic cell transplantation (HCT), including both nonmalignant conditions and myeloid diseases. Substituting fludarabine for cyclophosphamide (BuFlu) to reduce toxicity without an increase in relapse has been increasingly performed in children, but without comparison with BuCy. We retrospectively analyzed 1781 children transplanted from 2008 to 2014 to compare the effectiveness of BuCy with BuFlu. Nonmalignant and malignant disease populations were analyzed separately. Overall mortality was comparable for children with nonmalignant conditions who received BuFlu or BuCy (relative risk [RR], 1.14, P = .52). Lower incidences of sinusoidal obstruction syndrome (P = .04), hemorrhagic cystitis (P = .04), and chronic graft-versus-host disease (P = .02) were observed after BuFlu, but the influence of the conditioning regimen could not be assessed by multivariate analysis because of the low frequency of these complications. Children transplanted for malignancies were more likely to receive BuFlu if they had higher hematopoietic cell transplantation-comorbidity index scores (P < .001) or their donor was unrelated and HLA-mismatched (P = .004). Nevertheless, there were no differences in transplant toxicities and comparable transplant-related mortality (RR, 1.2; P = .46), relapse (RR, 1.2; P = .15), and treatment failure (RR, 1.2; P = .12). BuFlu was associated with higher overall mortality (RR, 1.4; P = .008) related to inferior postrelapse survival (P = .001). Our findings demonstrated that outcomes after BuFlu are similar to those for BuCy for children, but for unclear reasons, those receiving BuFlu for malignancy may be at risk for shorter postrelapse survival.

Although transplant practices have changed over the last decades, no information is available on trends in incidence and outcome of chronic graft-versus-host disease (cGVHD) over time. This study used the central database of the Center for International Blood and Marrow Transplant Research (CIBMTR) to describe time trends for cGVHD incidence, nonrelapse mortality, and risk factors for cGVHD. The 12-year period was divided into 3 intervals, 1995 to 1999, 2000 to 2003, and 2004 to 2007, and included 26,563 patients with acute leukemia, chronic myeloid leukemia, and myelodysplastic syndrome. Multivariate analysis showed an increased incidence of cGVHD in more recent years (odds ratio = 1.19, P

FMS-like tyrosine kinase 3 (FLT3) internal tandem duplication (ITD) is a somatic mutation associated with poor outcome when treated with chemotherapy alone. In children, hematopoietic stem cell transplantation (HSCT) is recommended, but very limited data on outcome are reported. We determined the outcome of 29 children with FLT3/ITD–positive acute myelogenous leukemia (AML) who underwent allogeneic HSCT in 4 pediatric centers. Eleven patients (38%) received matched related donor hematopoietic stem cells and 18 (62%) received alternative donors. Eighteen patients (62%) received total body irradiation (TBI)–based regimens. No patients experienced transplantation-related mortality. Eleven patients (38%) experienced relapsed disease. The cumulative incidence of relapse at 2 years was 34.7% (95% confidence interval [CI], 20.4% to 54.9%). Two-year disease-free survival (DFS) and overall survival (OS) were 65.3% (95% CI, 45.1% to 79.6%) and 82.2% (95% CI, 58.5% to 91.3%), respectively. There was no difference in the DFS of patients who received transplants from related donors versus the DFS of those who received transplants from alternative donors (hazard ratio [HR], 2.64; 95% CI, .79 to 8.76; P = .10), using univariate analysis. Patients with higher FLT3/ITD ratio at diagnosis had significantly worse DFS (HR, 1.42; 95% CI, 1.04 to 1.93; P = .03). The use of TBI in the preparative regimen was associated with superior DFS (HR, .29; 95% CI, .08 to .99; P = .04) and OS (HR, .07; 95% CI, .01 to .62; P = .002). We conclude that allogeneic HSCT improves DFS and OS in children with FLT3/ITD–positive AML compared with what has been reported in those treated with chemotherapy alone.

We analyzed the outcomes of patients who survived disease-free for 1 year or more after a second allogeneic hematopoietic cell transplantation (HCT) for relapsed acute leukemia or myelodysplastic syndromes between 1980 and 2009. A total of 1285 patients received a second allogeneic transplant after disease relapse; among these, 325 were relapse free at 1 year after the second HCT. The median time from first to second HCT was 17 and 24 months for children and adults, respectively. A myeloablative preparative regimen was used in the second transplantation in 62% of children and 45% of adult patients. The overall 10-year conditional survival rates after second transplantation in this cohort of patients who had survived disease-free for at least 1 year was 55% in children and 39% in adults. Relapse was the leading cause of mortality (77% and 54% of deaths in children and adults, respectively). In multivariate analyses, only disease status before second HCT was significantly associated with higher risk for overall mortality (hazard ratio, 1.71 for patients with disease not in complete remission before second HCT, P

Hematopoietic cell transplantation (HCT) is effective in the treatment of inherited marrow failure disorders and other nonmalignant diseases. Conventional myeloablative conditioning regimens have been associated with high transplant-related mortality, particularly in patients with comorbid conditions. Here we report on 14 patients with marrow failure disorders (Shwachman-Diamond syndrome, n = 3; Diamond Blackfan anemia, n = 4; GATA2 deficiency, n = 2; paroxysmal nocturnal hemoglobinuria, n = 4; and an undefined marrow failure disorder, n = 1) who underwent HCT on a prospective, phase II, multicenter clinical trial. Patients were given HLA-matched related (n = 2) or unrelated (n = 12) grafts after conditioning with treosulfan (42 g/m2), fludarabine (150 mg/m2), ± thymoglobulin (n = 11; 6 mg/kg). All patients engrafted. At a median follow-up of 3 years, 13 patients are alive with complete correction of their underlying disease. These results indicate that the combination of treosulfan, fludarabine, and thymoglobulin is effective at establishing donor engraftment with a low toxicity profile and excellent disease-free survival in patients with marrow failure disorders.

Children with cancer and HSCT recipients are at high risk for common viral infections. We sought to define the viral etiology of ARI and identify risk factors. Nasal wash samples were collected from pediatric hematology-oncology patients and HSCT recipients with ARI during the 2003-2005 winter seasons. Real-time RT-PCR was performed to detect Flu A, influenza B, RSV, PIV 1-3, human MPV, and HRV. HRV specimens were sequenced and genotyped. Seventy-eight samples from 62 children were included. Viruses were detected in 31 of 78 samples (40%). HRV were detected most frequently, in 16 (52%) including five HRVC; followed by seven (22%) RSV, five (16%) Flu A, four (13%) MPV, and two (6%) PIV2. There was a trend toward higher risk of viral infection for children in day care. Only 8% of the study children had received influenza vaccine. HRV, including the recently discovered HRVC, are an important cause of infection in pediatric oncology and HSCT patients. Molecular testing is superior to conventional methods and should be standard of care, as HRV are not detected by conventional methods.

Several studies have shown comparable survival outcomes with different graft sources, but the relative resource needs of hematopoietic cell transplantation (HCT) by graft source have not been well studied. We compared total hospital length of stay in the first 100 days after HCT in 1577 patients with acute leukemia in remission who underwent HCT with an umbilical cord blood (UCB), matched unrelated donor (MUD), or mismatched unrelated donor (MMUD) graft between 2008 and 2011. To ensure a relatively homogenous study population, the analysis was limited to patients with acute myelogenous leukemia and acute lymphoblastic leukemia in first or second complete remission who underwent HCT in the United States. To account for early deaths, we compared the number of days alive and out of the hospital in the first 100 days post-transplantation. For children who received myeloablative conditioning, the median time alive and out of the hospital in the first 100 days was 50 days for single UCB recipients, 54 days for double UCB recipients, and 60 days for MUD bone marrow (BM) recipients. In multivariate analysis, use of UCB was significantly associated with fewer days alive and out of the hospital compared with MUD BM. For adults who received myeloablative conditioning, the median time alive and out of the hospital in first 100 days was 52 days for single UCB recipients, 55 days for double UCB recipients, 69 days for MUD BM recipients, 75 days for MUD peripheral blood stem cell (PBSC) recipients, 63 days for MMUD BM recipients, and 67 days for MMUD PBSC recipients. In multivariate analysis, UCB and MMUD BM recipients had fewer days alive and out of the hospital compared with recipients of other graft sources. For adults who received a reduced-intensity preparative regimen, the median time alive and out of the hospital during the first 100 days was 65 days for single UCB recipients, 63 days for double UCB recipients, 79 days for MUD PBSC recipients, and 79 days for MMUD PBSC recipients. Similar to the other 2 groups, receipt of UCB was associated with a fewer days alive and out of the hospital. In conclusion, length of stay in the first 100 days post-transplantation varies by graft source and is longer for UCB HCT recipients. These data provide insight into the resource needs of patients who undergo HCT with these various graft sources.

There are limited data on the optimal dosing and schedule of G-CSF priming prior to BM harvest. We evaluated the safety and efficacy of three days of G-CSF of primed BM from related pediatric donors. Forty-five children were treated. All donors received 5 μg/kg per day of G-CSF as a single subcutaneous injection for three consecutive days prior to the BM harvest. The median age of the donors was seven yr (range, 0.8-18) and no donor experienced major adverse events related to G-CSF administration. The median age for the recipients was five yr (0.3-16 yr). Thirty-five patients had non-malignant disorders. The median dose of nucleated (TNC) and CD34+, CD3 cells infused per recipient weight was 5.4 × 10(8) /kg (range, 0.61-17), 4.7 × 10(6) /kg (range, 1.6-19), and 43.8 × 10(6) /kg (range, 1.8-95), respectively. All patients achieved neutrophil and platelets engraftment, at a median of 15 (range, 10-22) and 23 days (range, 13-111), respectively. At a median follow up of 60 months (range 12-100), the estimated five yr overall and EFS was 91% and 80%, respectively. Collection of BM following three days of G-CSF priming from pediatric donors is safe and results in high TNC and CD34+ cell yield.

Background The role of the neutropenic diet in the development of infections in oncology and stem cell transplant (SCT) patients is controversial. There is no data on the use of the neutropenic diet among pediatric oncologists. Methods A self-administered electronic survey was sent to 1,639 pediatric oncologists at 198 institutions who are members of Children's Oncology Group. A pediatric dietitian and pediatric oncologists developed, pretested, and modified the survey for item clarification. Results Five hundred fifty-seven physicians (34%) responded representing 174 (87%) of the 198 member institutions. More than half of respondents (57%) report implementing the neutropenic diet at their facility. In a multivariate analysis, being a stem cell transplant (SCT) center was the only significant factor associated with implementing a neutropenic diet (OR: 6.06, 95% CI, 2.88–12.738, P

Background Approximately 40-50% of HSCT are ABO incompatible and bone marrow (BM) products contain 25-35% of incompatible RBCs. RBC reduction can be performed using several different techniques including manual RBC sedimentation using hydroxyethyl starch (HES) or Ficoll-Hypaque density gradient separation with centrifugation or sepax automated device. Volume reduction is often necessary in pediatric patients who cannot tolerate large BM volume. Manual separation can be associated with cell loss of up to 50% of the total nucleated cell dose. Methods We have performed RBC depletion and volume reduction using Optia Spectra following the manufacturer instructions. Each BM unit was processed for 5-10 cycles at 120 ml/minute flow. Results Since 2016 we have processed 22 BM products using this automated system for ABO incompatibility (major mismatch in 10 and minor mismatch in 6) or for volume reduction (n=6). The median age of patients was 23.5 years (range 1 - 62) with 9 patients Conclusion Automated bone marrow processing using the Optia Spectra is efficient in RBC and volume reduction and can result in excellent cell recovery.

Introduction Allogeneic HSCT (alloHSCT) offers a potential cure for patients with AML; however, 40% of AML patients receiving alloHSCT will experience relapsed disease. Second alloHSCT can offer the best long-term survival but is associated with significant toxicity. Preliminary data suggests that TBI only preparative regimen with post-transplant HD Cy is associated with lower TRM compared to TBI/Cy. Methods We report on four patients with AML who experienced relapsed disease following alloHSCT with busulfan-containing preparative regimen. All patients received re-induction chemotherapy and 3 achieved remission. Two patients had significant pre-existing morbidities prior to transplant, and one patient had refractory disease. Each patient received a second alloHSCT transplant using a TBI only preparative regimen (1200-1320 cGy) and GVHD prophylaxis included HD Cy 50mg/kg/daily on Days +3 and +4 as well as tacrolimus and MMF starting on Day +5. MMF was discontinued at Day +30 post-transplant. Three patients received bone marrow from 10/10 HLA-matched unrelated donors. One patient received PBSC from an HLA matched parent donor. Results All four patients tolerated transplant with no transplant related mortality and no grade 3 toxicity. All patients achieved neutrophil and platelet engraftment at an average of 19.5 (range 14-25) and 19 (range 15-23) days post transplant, respectively. Fifty percent of the patients developed acute Grade I-II skin GVHD. One patient developed mild, limited chronic GVHD. All patients are currently alive and are at least one year post second-transplant. Three of the four (75%) patients are off immune suppression and remain in remission at 14, 15 and 20 months post HSCT. Conclusion TBI only preparative regimen with post transplant HD Cy may offer an alternative treatment option for AML patients who experience relapse following a prior busulfan-containing alloHSCT.

Background In haploidentical hematopoietic stem cell transplantation (HCT), the presence of recipient pre-transplant Donor Specific Antibodies (DSA) is a strong risk factor for impaired engraftment. However, the impact of borderline pre-transplant DSA levels is not well defined. We performed a retrospective study on borderline DSA levels in 38 haplo-HCT. Subjects and Methods In this single center, retrospective study, we analyzed 38 patients (median age= 59.0 years; range=28-77). All patients were screened for the presence of pre-transplant HLA antibodies and each recipient: donor pair underwent T- and B-cell flow cytometry crossmatch (FCM). DSA levels were assigned as negative (MFI Results 33 haplo-HCT recipients were both DSA (MFI 95%) donor chimerism at day 30 and 100 was 26/30 (87%) and 25/27 (93%) for CD3; 30/31 (97%) and 26/28 (93%) for CD33 respectively. Twelve patients (36%) experienced grade 2-4 aGVHDand 4/33 (12%) had extensive cGVHD. Disease progression was observed in 9/33 (27%) patients, with an overall survival of 67% (22/33). Conclusions The presence of pre-transplant borderline levels of DSA does not appear deleterious for haplo-HCT outcomes using PBSC grafts.