Posttransplantation late complications increase over time for patients with SCID: A Primary Immune Deficiency Treatment Consortium (PIDTC) landmark study.

BACKGROUND: The Primary Immune Deficiency Treatment Consortium (PIDTC) enrolled children in the United States and Canada onto a retrospective multicenter natural history study of hematopoietic cell transplantation (HCT). OBJECTIVE: We investigated outcomes of HCT for severe combined immunodeficiency (SCID). METHODS: We evaluated the chronic and late effects (CLE) after HCT for SCID in 399 patients transplanted from 1982 to 2012 at 32 PIDTC centers. Eligibility criteria included survival to at least 2 years after HCT without need for subsequent cellular therapy. CLE were defined as either conditions present at any time before 2 years from HCT that remained unresolved (chronic), or new conditions that developed beyond 2 years after HCT (late). RESULTS: The cumulative incidence of CLE was 25% in those alive at 2 years, increasing to 41% at 15 years after HCT. CLE were most prevalent in the neurologic (9%), neurodevelopmental (8%), and dental (8%) categories. Chemotherapy-based conditioning was associated with decreased-height z score at 2 to 5 years after HCT (P < .001), and with endocrine (P < .001) and dental (P = .05) CLE. CD4 count of ≤500 cells/µL and/or continued need for immunoglobulin replacement therapy >2 years after transplantation were associated with lower-height z scores. Continued survival from 2 to 15 years after HCT was 90%. The presence of any CLE was associated with increased risk of late death (hazard ratio, 7.21; 95% confidence interval, 2.71-19.18; P < .001). CONCLUSION: Late morbidity after HCT for SCID was substantial, with an adverse impact on overall survival. This study provides evidence for development of survivorship guidelines based on disease characteristics and treatment exposure for patients after HCT for SCID.

Relevance of lymphocyte proliferation to PHA in severe combined immunodeficiency (SCID) and T cell lymphopenia.

Severe combined immunodeficiency (SCID) is characterized by a severe deficiency in T cell numbers. We analyzed data collected (n = 307) for PHA-based T cell proliferation from the PIDTC SCID protocol 6901, using either a radioactive or flow cytometry method. In comparing the two groups, a smaller number of the patients tested by flow cytometry had <10% of the lower limit of normal proliferation as compared to the radioactive method (p = 0.02). Further, in patients with CD3+ T cell counts between 51 and 300 cells/µL, there was a higher proliferative response with the PHA flow assay compared to the 3H-T assay (p < 0.0001), suggesting that the method of analysis influences the resolution and interpretation of PHA results. Importantly, we observed many SCID patients with profound T cell lymphopenia having normal T cell proliferation when assessed by flow cytometry. We recommend this test be considered only as supportive in the diagnosis of typical SCID.

Measuring the effect of newborn screening on survival after haematopoietic cell transplantation for severe combined immunodeficiency: a 36-year longitudinal study from the Primary Immune Deficiency Treatment Consortium.

BACKGROUND: Severe combined immunodeficiency (SCID) is fatal unless durable adaptive immunity is established, most commonly through allogeneic haematopoietic cell transplantation (HCT). The Primary Immune Deficiency Treatment Consortium (PIDTC) explored factors affecting the survival of individuals with SCID over almost four decades, focusing on the effects of population-based newborn screening for SCID that was initiated in 2008 and expanded during 2010-18. METHODS: We analysed transplantation-related data from children with SCID treated at 34 PIDTC sites in the USA and Canada, using the calendar time intervals 1982-89, 1990-99, 2000-09, and 2010-18. Categorical variables were compared by χ2 test and continuous outcomes by the Kruskal-Wallis test. Overall survival was estimated by the Kaplan-Meier method. A multivariable analysis using Cox proportional hazards regression models examined risk factors for HCT outcomes, including the variables of time interval of HCT, infection status and age at HCT, trigger for diagnosis, SCID type and genotype, race and ethnicity of the patient, non-HLA-matched sibling donor type, graft type, GVHD prophylaxis, and conditioning intensity. FINDINGS: For 902 children with confirmed SCID, 5-year overall survival remained unchanged at 72%-73% for 28 years until 2010-18, when it increased to 87% (95% CI 82·1-90·6; n=268; p=0·0005). For children identified as having SCID by newborn screening since 2010, 5-year overall survival was 92·5% (95% CI 85·8-96·1), better than that of children identified by clinical illness or family history in the same interval (79·9% [69·5-87·0] and 85·4% [71·8-92·8], respectively [p=0·043]). Multivariable analysis demonstrated that the factors of active infection (hazard ratio [HR] 2·41, 95% CI 1·56-3·72; p<0·0001), age 3·5 months or older at HCT (2·12, 1·38-3·24; p=0·001), Black or African-American race (2·33, 1·56-3·46; p<0·0001), and certain SCID genotypes to be associated with lower overall survival during all time intervals. Moreover, after adjusting for several factors in this multivariable analysis, HCT after 2010 no longer conveyed a survival advantage over earlier time intervals studied (HR 0·73, 95% CI 0·43-1·26; p=0·097). This indicated that younger age and freedom from infections at HCT, both directly driven by newborn screening, were the main drivers for recent improvement in overall survival. INTERPRETATION: Population-based newborn screening has facilitated the identification of infants with SCID early in life, in turn leading to prompt HCT while avoiding infections. Public health programmes worldwide can benefit from this definitive demonstration of the value of newborn screening for SCID. FUNDING: National Institute of Allergy and Infectious Diseases, Office of Rare Diseases Research, and National Center for Advancing Translational Sciences.

KIR-favorable TCR-αß/CD19-depleted haploidentical HCT in children with ALL/AML/MDS: primary analysis of the PTCTC ONC1401 trial.

We performed a prospective multicenter study of T-cell receptor αß (TCR-αß)/CD19-depleted haploidentical hematopoietic cell transplantation (HCT) in children with acute leukemia and myelodysplastic syndrome (MDS), to determine 1-year disease-free survival (DFS) and compare 2-year outcomes with recipients of other donor cell sources. Fifty-one patients aged 0.7 to 21 years were enrolled; donors were killer immunoglobulin-like receptor (KIR) favorable based on ligand mismatch and/or high B content. The 1-year DFS was 78%. Superior 2-year DFS and overall survival (OS) were noted in patients <10 years of age, those treated with reduced toxicity conditioning (RTC) rather than myeloablative conditioning, and children with minimal residual disease <0.01% before HCT. Multivariate analysis comparing the KIR-favorable haploidentical cohort with controls showed similar DFS and OS compared with other donor cell sources. Multivariate analysis also showed a marked decrease in the risk of grades 2 to 4 and 3 to 4 acute graft versus host disease (aGVHD), chronic GVHD, and transplant-related mortality vs other donor cell sources. Ethnic and racial minorities accounted for 53% of enrolled patients, and data from a large cohort of recipients/donors screened for KIR showed that >80% of recipients had a KIR-favorable donor by our definition, demonstrating that this approach is broadly applicable to groups often unable to find donors. This prospective, multicenter study showed improved outcomes using TCR-αß/CD19-depleted haploidentical donors using RTC for children with acute leukemia and MDS. Randomized trials comparing this approach with matched unrelated donors are warranted. This trial was registered at https://clinicaltrials.gov as #NCT02646839.

Aberrant T-cell exhaustion in severe combined immunodeficiency survivors with poor T-cell reconstitution after transplantation.

BACKGROUND: Severe combined immunodeficiency (SCID) comprises rare inherited disorders of immunity that require definitive treatment through hematopoietic cell transplantation (HCT) or gene therapy for survival. Despite successes of allogeneic HCT, many SCID patients experience incomplete immune reconstitution, persistent T-cell lymphopenia, and poor long-term outcomes. OBJECTIVE: We hypothesized that CD4+ T-cell lymphopenia could be associated with a state of T-cell exhaustion in previously transplanted SCID patients. METHODS: We analyzed markers of exhaustion in blood samples from 61 SCID patients at a median of 10.4 years after HCT. RESULTS: Compared to post-HCT SCID patients with normal CD4+ T-cell counts, those with poor T-cell reconstitution showed lower frequency of naive CD45RA+/CCR7+ T cells, recent thymic emigrants, and TCR excision circles. They also had a restricted TCR repertoire, increased expression of inhibitory receptors (PD-1, 2B4, CD160, BTLA, CTLA-4), and increased activation markers (HLA-DR, perforin) on their total and naive CD8+ T cells, suggesting T-cell exhaustion and aberrant activation, respectively. The exhaustion score of CD8+ T cells was inversely correlated with CD4+ T-cell count, recent thymic emigrants, TCR excision circles, and TCR diversity. Exhaustion scores were higher among recipients of unconditioned HCT, especially when further in time from HCT. Patients with fewer CD4+ T cells showed a transcriptional signature of exhaustion. CONCLUSIONS: Recipients of unconditioned HCT for SCID may develop late post-HCT T-cell exhaustion as a result of diminished production of T-lineage cells. Elevated expression of inhibitory receptors on their T cells may be a biomarker of poor long-term T-cell reconstitution.

Immune profile differences between chronic GVHD and late acute GVHD: results of the ABLE/PBMTC 1202 studies.

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 CD56bright regulatory NK cells, and increased ST2 and soluble CD13. Active L-aGVHD before day 114 had additional abnormalities in naive Th, naive regulatory T (Treg) cell populations, and cytokines, and active cGVHD had an increase in PD-1- and a decrease in PD-1+ memory Treg 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.

Excellent outcomes following hematopoietic cell transplantation for Wiskott-Aldrich syndrome: a PIDTC report.

Wiskott-Aldrich syndrome (WAS) is an X-linked disease caused by mutations in the WAS gene, leading to thrombocytopenia, eczema, recurrent infections, autoimmune disease, and malignancy. Hematopoietic cell transplantation (HCT) is the primary curative approach, with the goal of correcting the underlying immunodeficiency and thrombocytopenia. HCT outcomes have improved over time, particularly for patients with HLA-matched sibling and unrelated donors. We report the outcomes of 129 patients with WAS who underwent HCT at 29 Primary Immune Deficiency Treatment Consortium centers from 2005 through 2015. Median age at HCT was 1.2 years. Most patients (65%) received myeloablative busulfan-based conditioning. With a median follow-up of 4.5 years, the 5-year overall survival (OS) was 91%. Superior 5-year OS was observed in patients <5 vs ≥5 years of age at the time of HCT (94% vs 66%; overall P = .0008). OS was excellent regardless of donor type, even in cord blood recipients (90%). Conditioning intensity did not affect OS, but was associated with donor T-cell and myeloid engraftment after HCT. Specifically, patients who received fludarabine/melphalan-based reduced-intensity regimens were more likely to have donor myeloid chimerism <50% early after HCT. In addition, higher platelet counts were observed among recipients who achieved full (>95%) vs low-level (5%-49%) donor myeloid engraftment. In summary, HCT outcomes for WAS have improved since 2005, compared with prior reports. HCT at a younger age continues to be associated with superior outcomes supporting the recommendation for early HCT. High-level donor myeloid engraftment is important for platelet reconstitution after either myeloablative or busulfan-containing reduced intensity conditioning. (This trial was registered at www.clinicaltrials.gov as #NCT02064933.).

Physician risk perceptions and surveillance practices for tyrosine kinase inhibitor long-term effects in pediatric CML.

Chronic myeloid leukemia (CML) is effectively treated with long-term tyrosine kinase inhibitor (TKI) therapy, yet little is known about risks of prolonged TKI exposure in young patients, and long-term effect monitoring is not standardized. We surveyed North American pediatric oncologists (n = 119) to evaluate perceived risk of and surveillance practices for potential toxicities associated with prolonged TKI exposure in children and adolescents/young adults (AYAs) with CML. Survey domains included general and specific risk perceptions and surveillance practices for asymptomatic patients on chronic TKI therapy. We analyzed data descriptively and explored relationships between risk perceptions and surveillance. Risk perceptions varied among oncologists but were similar across six categories (thyroid, cardiac, vascular, metabolic, fertility, psychologic), with less than one-third rating each risk as moderate or high in pediatric and AYA patients. More oncologists perceived moderate or high risk of growth abnormalities in children (62% pediatric, 14% AYA) and financial toxicity in all patients (60% pediatric, 64% AYA). A greater proportion of oncologists with moderate or high perceived risk of thyroid abnormalities reported testing thyroid function compared to those with lower perceived risk; patterns for metabolic risk/lipid tests and cardiac risk/tests were similar. In summary, we found that pediatric oncologists had variable risk perceptions and surveillance practices for potential toxicities associated with prolonged TKI exposure. Standardizing surveillance would help quantify risks and refine recommendations.Supplemental data for this article is available online at https://doi.org/10.1080/08880018.2021.2017085 .

Infections in Infants with SCID: Isolation, Infection Screening, and Prophylaxis in PIDTC Centers.

PURPOSE: The Primary Immune Deficiency Treatment Consortium (PIDTC) enrolled children with severe combined immunodeficiency (SCID) in a prospective natural history study of hematopoietic stem cell transplant (HSCT) outcomes over the last decade. Despite newborn screening (NBS) for SCID, infections occurred prior to HSCT. This study's objectives were to define the types and timing of infection prior to HSCT in patients diagnosed via NBS or by family history (FH) and to understand the breadth of strategies employed at PIDTC centers for infection prevention. METHODS: We analyzed retrospective data on infections and pre-transplant management in patients with SCID diagnosed by NBS and/or FH and treated with HSCT between 2010 and 2014. PIDTC centers were surveyed in 2018 to understand their practices and protocols for pre-HSCT management. RESULTS: Infections were more common in patients diagnosed via NBS (55%) versus those diagnosed via FH (19%) (p = 0.012). Outpatient versus inpatient management did not impact infections (47% vs 35%, respectively; p = 0.423). There was no consensus among PIDTC survey respondents as to the best setting (inpatient vs outpatient) for pre-HSCT management. While isolation practices varied, immunoglobulin replacement and antimicrobial prophylaxis were more uniformly implemented. CONCLUSION: Infants with SCID diagnosed due to FH had lower rates of infection and proceeded to HSCT more quickly than did those diagnosed via NBS. Pre-HSCT management practices were highly variable between centers, although uses of prophylaxis and immunoglobulin support were more consistent. This study demonstrates a critical need for development of evidence-based guidelines for the pre-HSCT management of infants with SCID following an abnormal NBS. TRIAL REGISTRATION: NCT01186913.

Benefits and challenges with diagnosing chronic and late acute GVHD in children using the NIH consensus criteria.

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.

Reduced-toxicity conditioning regimen with busulfan, fludarabine, rATG, and 400 cGy TBI in pediatric patients undergoing hematopoietic stem cell transplant for high-risk hematologic malignancies.

BACKGROUND: Myeloablative conditioning regimens decrease the risk of relapse in pediatric patients undergoing allogeneic hematopoietic stem cell transplant (HCT) for hematologic malignancies, but cause significant toxicities PROCEDURE: This prospective study evaluated the use of a reduced-toxicity, myeloablative regimen with dose-adjusted busulfan, fludarabine, antithymocyte globulin and 400 cGy of total body irradiation in 40 patients < 21 years of age undergoing HCT for high-risk leukemias. Busulfan pharmacokinetics were measured to target 4000 µmol*min/day in the first 30 patients; this was increased to 5000 µmol*min/day in the subsequent 10 in efforts to further decrease relapse risk RESULTS: Overall survival at two- and five-years post-HCT was 67% and 51%, respectively. Relapse occurred in 11 patients (28%) at a median of seven months and was the leading cause of death. Transplant-related mortality was 8% and 13% at 100 days and one-year post-HCT, respectively. Trends toward improved survival were seen in patients transplanted for myeloid disease using bone marrow as stem cell source who achieved a busulfan AUC > 4000 µmol*min/day with two-year relapse-free survival approaching 80% CONCLUSIONS: This conditioning regimen is safe and effective in patients with high-risk leukemias, particularly myeloid disease. Larger studies are needed to compare its safety and efficacy to other myeloablative regimens in this population.

Study 275: Updated Expanded Access Program for Remestemcel-L in Steroid-Refractory Acute Graft-versus-Host Disease in Children.

Clinical outcomes in children with steroid-refractory acute graft-versus-host disease (SR-aGVHD) are generally poor, with a high mortality rate and limited therapeutic options. Here we report our updated investigational experience with mesenchymal stromal cell (MSC) therapy with remestemcel-L in a multicenter expanded access protocol (ClinicalTrials.gov identifier NCT00759018) in 241 children with aGVHD who failed to respond to steroids with or without other secondary and tertiary immunosuppressive therapies. A total of 241 children with grade B-D SR-aGVHD were enrolled at 50 sites in 8 countries and received 8 biweekly i.v. infusions of human MSCs, 2 × 106 per kg for 4 weeks, with an option for an additional 4 weekly infusions after day +28 for subjects who achieved either a partial response (PR) or mixed response. The mean age of the subjects was 9.6 years; 39% were female, and 60% were white. Most of the subjects had grade C (30%) or grade D (50%) disease, and in most cases, the subjects had failed to respond to other immunosuppressive agents after failing steroids. The primary endpoint was overall response (OR; the sum of complete response [CR] and PR) at day +28. Across all subjects, a 28-day OR was observed in 157 patients (65.1%), with 34 (14.1%) achieving CR and 123 (51.3%) achieving PR. Stratified by aGVHD grade at baseline, the OR rate at day +28 was 72.9% for patients with aGVHD grade B, 67.1% for those with aGVHD grade C, and 60.8% for those with aGVHD grade D. Survival through day +100, a secondary endpoint of the study, was 66.9% (n = 160 of 239). Importantly, survival through day +100 was significantly greater in subjects who achieved a day +28 OR compared with nonresponders (82.1% versus 38.6%; P < .001, log-rank test). Remestemcel-L safety was generally well tolerated, with no infusional toxicity and no identified safety concerns. In summary, this update to the remestemcel-L expanded access program confirms the reported clinical and survival benefits of remestemcel-L therapy in children with aGVHD who have exhausted all conventional therapeutic options.

A Phase 3, Single-Arm, Prospective Study of Remestemcel-L, Ex Vivo Culture-Expanded Adult Human Mesenchymal Stromal Cells for the Treatment of Pediatric Patients Who Failed to Respond to Steroid Treatment for Acute Graft-versus-Host Disease.

Steroid-refractory acute graft-versus-host disease (SR-aGVHD) following hematopoietic cell transplantation (HSCT) is associated with poor clinical outcomes. Currently, there are no safe and effective therapies approved for use in the pediatric population under the age of 12 years. Accordingly, there is an urgent need for new treatments that are safe, well tolerated, and effective in managing this debilitating and potentially fatal complication of HSCT. In early phase clinical trials, mesenchymal stromal cells (MSCs) have demonstrated efficacy in the treatment of acute GVHD (aGVHD) in pediatric patients. We now report the results of a phase 3, prospective, single-arm, multicenter study (NCT02336230) in 54 children with primary SR-aGVHD who were naive to other immunosuppressant therapies for aGVHD treated with MSC product (remestemcel-L) dosed at 2 × 106 cells/kg twice weekly for 4 weeks. Remestemcel-L therapy significantly improved day 28 overall response rate (OR) compared with the prespecified control OR value of 45% (70.4% versus 45%, P = .0003). The statistically significant OR (70.4%) was sustained through day 100, including an increase in complete response from 29.6% at day 28 to 44.4% at day 100. Overall survival was 74.1% at day 100 and 68.5% at day 180. Overall response in all participants at day 28 was highly predictive of improved survival through 180 days, and survival was significantly greater in day 28 responders compared with nonresponders through day 100 (86.8% versus 47.1% for responders and nonresponders, respectively, P = .0001) and through day 180 (78.9% versus 43.8%, P = .003). Remestemcel-L was well tolerated with no identified infusion-related toxicities or other safety concerns. This study provides robust, prospective evidence of the safety, tolerability, and efficacy of remestemcel-L as first-line therapy after initial steroid failure in pediatric SR-aGVHD.

Practice Patterns of Physician Treatment for Pediatric Chronic Myelogenous Leukemia.

Chronic myelogenous leukemia (CML) is a rare disease in children for which pediatric evidence-based guidelines are lacking. We designed an anonymous survey for practicing pediatric oncologists and bone marrow transplantation (BMT) physicians to assess their willingness to recommend BMT for a patient with CML based on various clinical scenarios. A total of 274 physicians responded to the survey (13.4% response rate). Nearly all pediatric oncologists and BMT physicians recommended against BMT at time of diagnosis of CML in the chronic phase, with only 8.0% and 1.9% recommending BMT if a matched sibling donor (MSD) and a matched unrelated donor (MUD), respectively, was available. Similarly, after a first poor response to tyrosine kinase inhibitor (TKI) therapy or hematologic relapse, physicians continued to recommend against BMT (39.5% and 23.3% recommended BMT in patients with a matched sibling donor and matched unrelated donor, respectively). However, 81.7% and 69.8% of respondents would recommend BMT after 2 hematologic relapses on TKI therapy, if an MSD and an MUD, respectively, were available. In addition, there was great interest in developing a clinical trial evaluating the safety and efficacy of stopping TKIs in children with CML who achieve and maintain a deep molecular response, with 86.7% of respondents stating they would offer such a trial to their pediatric patients. This survey highlights the need for evidence-based, pediatric-specific guidelines for the management of children and adolescents with CML.

Immune Reconstitution and Infection Patterns after Early Alemtuzumab and Reduced Intensity Transplantation for Nonmalignant Disorders in Pediatric Patients.

Hematopoietic stem cell transplantation (HSCT) is a therapeutic option for many nonmalignant disorders (NMD) and is curative or prevents disease progression. Reduced-intensity conditioning (RIC) in HSCT for NMD may reduce regimen-related acute toxicities and late complications. Myeloablation is often replaced by immune suppression in RIC regimens to support donor engraftment. The pace of immune reconstitution after immune suppression by RIC regimens is influenced by agents used, donor source, and graft-versus-host disease prophylaxis/treatment. In a multicenter trial (NCT 00920972) of HSCT for NMD, a RIC regimen consisting of alemtuzumab, fludarabine, and melphalan was substituted for myeloablation. Alemtuzumab was administered early (days -21 to -19) to mitigate major lymphodepletion of the incoming graft and the risk of graft rejection. Immune reconstitution and infectious complications were prospectively monitored for 1-year post-HSCT. Seventy-one patients met inclusion criteria for this report and received marrow or peripheral blood stem cell transplants. Immune reconstitution and infections are reported for related donor (RD) and unrelated donor (URD) transplants at 3 time-points (100days, 6 months, and 1 year post-HSCT). Natural killer cell recovery was rapid, and numbers normalized in both cohorts by day +100. Mean CD3, CD4, and CD8 T-lymphocyte numbers normalized by 6 months after RD HSCT and by 1 year in the URD group. CD4 and CD8 T-lymphocyte counts were significantly higher in patients who received RD HSCT at 6 months and at 1 year, respectively, post-HSCT compared with patients who received URD HSCT. The pace of CD19 B-cell recovery was markedly different between RD and URD cohorts. Mean B-cell numbers were normal by day 100 after RD HSCT but took 1 year post-HSCT to normalize in the URD cohort. Despite these differences in immune reconstitution, the timing and nature of infections did not differ between the groups, presumably because of comparable T-lymphocyte recovery. Immune reconstitution occurred at a faster pace than in prior reports using RIC with T-cell depletion. The incidence of infections was similar for both cohorts and occurred most frequently in the first 100days post-HSCT. Viral and fungal infections occurred at a lower incidence in this cohort, with "early" alemtuzumab compared with regimens administering serotherapy in the peritransplantation period. Patients were susceptible to bacterial infections primarily in the first 100days irrespective of donor source and had no increase in mortality from the same. The overall mortality rate from infections was 1.4% at 1 year. Close monitoring and prophylaxis against bacterial infections in the first 100days post-HSCT is necessary but is followed by robust immune reconstitution, especially in the T-cell compartment.

Cell-free DNA next-generation sequencing successfully detects infectious pathogens in pediatric oncology and hematopoietic stem cell transplant patients at risk for invasive fungal disease.

BACKGROUND: We sought to determine if next-generation sequencing (NGS) of microbial cell-free DNA (cfDNA) in plasma would detect pathogens in pediatric patients at risk for invasive fungal disease (IFD). PROCEDURES: Pediatric hematology, oncology, and stem cell transplant patients deemed at risk for new IFD had blood samples drawn at three time-points separated by 1-month intervals. The primary outcome measure was detection of fungal pathogens compared to standard clinical testing. Secondary outcomes included identification of other infectious pathogens, relationship to European Organization for Research and Treatment of Cancer's Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases' Mycoses Study Group (EORTC/MSG) guidelines, and assessment of antifungal therapy. RESULTS: NGS identified fungal pathogens in seven of 40 at-risk patients for IFD and results were identical in four of six proven cases, including Aspergillus fumigatus by lung biopsy, Candida albicans by blood or pancreatic pseudocyst cultures, and Rhizopus delemar by skin biopsy. Rhizopus oryzae identified on skin biopsy and A. fumigatus isolated on day 27 of 28 of culture from lung biopsy were not detected by cfDNA NGS, possibly due to lack of bloodstream penetration and questionable pathogenicity, respectively. Numerous DNA viruses were detected in patients with prolonged febrile neutropenia or abnormal imaging. Extended antifungal therapy was used in 73% of patients. Follow-up cfDNA sequencing in patients who were positive at enrollment was negative at 1 and 2 months. CONCLUSIONS: cfDNA NGS detected fungal pathogens from blood confirming its potential to guide treatment decisions in pediatric patients at risk for IFD and limit excessive empiric antifungal use. Future studies are needed to better understand the sensitivity and specificity of this approach.

Unrelated Donor Transplantation in Children with Thalassemia using Reduced-Intensity Conditioning: The URTH Trial.

Allogeneic hematopoietic stem cell transplantation (HSCT) can cure transfusion-dependent thalassemia (TDT). In a multicenter trial we investigated the efficacy of reduced-intensity conditioning (RIC) before unrelated donor (URD) HSCT in children with TDT. Thirty-three children, ages 1 to 17 years, received bone marrow (BM) or umbilical cord blood (UCB) allografts. Median time to neutrophil engraftment was 13 days (range, 10 to 25) and 24 days (range, 18 to 49) and platelet engraftment 23 days (range, 12 to 46) and 50 days (range, 31 to 234) after BM and UCB allografts, respectively. With a median follow-up of 58 months (range, 7 to 79), overall and thalassemia-free survival was 82% (95% CI, .64% to .92%) and 79% (95% CI, .6% to .9%), respectively. The cumulative incidence of grades II to IV acute graft-versus-host disease (GVHD) after BM and UCB allografts was 24% and 44%; the 2-year cumulative incidence of chronic extensive GVHD was 29% and 21%, respectively; 71% of BM and 91% of UCB recipients discontinued systemic immunosuppression by 2 years. Six patients who had Pesaro risk class 2 (n = 5) and class 3 (n = 1) died of GVHD (n = 3), viral pneumonitis (n = 2) and pulmonary hemorrhage (n = 1). Outcomes after this RIC compared favorably with URD HSCT outcomes for TDT and supported engraftment in 32 of 33 patients. Efforts to reduce GVHD and infectious complications are being pursued further.

A trial of unrelated donor marrow transplantation for children with severe sickle cell disease.

Children with sickle cell disease experience organ damage, impaired quality of life, and premature mortality. Allogeneic bone marrow transplant from an HLA-matched sibling can halt disease progression but is limited by donor availability. A Blood and Marrow Transplant Clinical Trials Network (BMT CTN) phase 2 trial conducted from 2008 to 2014 enrolled 30 children aged 4 to 19 years; 29 were eligible for evaluation. The primary objective was 1-year event-free survival (EFS) after HLA allele-matched (at HLA-A, -B, -C, and -DRB1 loci) unrelated donor transplant. The conditioning regimen included alemtuzumab, fludarabine, and melphalan. Graft-versus-host disease (GVHD) prophylaxis included calcineurin inhibitor, short-course methotrexate, and methylprednisolone. Transplant indications included stroke (n = 12), transcranial Doppler velocity >200 cm/s (n = 2), ≥3 vaso-occlusive pain crises per year (n = 12), or ≥2 acute chest syndrome episodes (n = 4) in the 2 years preceding enrollment. Median follow-up was 26 months (range, 12-62 months); graft rejection was 10%. The 1- and 2-year EFS rates were 76% and 69%, respectively. The corresponding rates for overall survival were 86% and 79%. The day 100 incidence rate of grade II-IV acute GVHD was 28%, and the 1-year incidence rate of chronic GVHD was 62%; 38% classified as extensive. There were 7 GVHD-related deaths. A 34% incidence of posterior reversible encephalopathy syndrome was noted in the first 6 months. Although the 1-year EFS met the prespecified target of ≥75%, this regimen cannot be considered sufficiently safe for widespread adoption without modifications to achieve more effective GVHD prophylaxis. The BMT CTN #0601 trial was registered at www.clinicaltrials.gov as #NCT00745420.

High-dose chemotherapy and autologous hematopoietic stem-cell rescue for treatment of relapsed and refractory Wilms tumor: Re-evaluating outcomes.

Wilms tumor (WT) treatment regimens are curative for more than 80% of patients, but those with relapsed or refractory disease continue to have poor outcomes. High-dose chemotherapy followed by autologous stem cell rescue is often utilized although outcomes remain variable. We report on HD-ASCR outcomes in 24 patients with relapsed or refractory Wilms tumor. Three-year disease free and overall survival are 46% and 60%, respectively, which is similar to those reported for conventional salvage therapies. These outcomes suggest that conventional salvage therapies should be employed for relapsed and refractory WT rather than HD-ASCR.