Evaluating cell culture reliability in pediatric brain tumor primary cells through DNA methylation profiling.

In vitro models of pediatric brain tumors (pBT) are instrumental for better understanding the mechanisms contributing to oncogenesis and testing new therapies; thus, ideally, they should recapitulate the original tumor. We applied DNA methylation (DNAm) and copy number variation (CNV) profiling to characterize 241 pBT samples, including 155 tumors and 86 pBT-derived cell cultures, considering serum vs serum-free conditions, late vs early passages, and dimensionality (2D vs 3D cultures). We performed a t-SNE classification and identified differentially methylated regions in tumors compared to cell models. Early cell cultures recapitulate the original tumor, but serum media and 2D culturing were demonstrated to significantly contribute to the divergence of DNAm profiles from the parental ones. All divergent cells clustered together acquiring a common deregulated epigenetic signature suggesting a shared selective pressure. We identified a set of hypomethylated genes shared among unfaithful cells converging on response to growth factors and migration pathways, such as signaling cascade activation, tissue organization, and cellular migration. In conclusion, DNAm and CNV are informative tools that should be used to assess the recapitulation of pBT-cells from parental tumors.

GD2-targeting CAR T-cell therapy for patients with GD2+ medulloblastoma.

PURPOSE: Medulloblastoma (MB), the most common childhood malignant brain tumor, has a poor prognosis in about 30% of patients. The current standard of care, which includes surgery, radiation and chemotherapy, is often responsible for cognitive, neurologic and endocrine side effects. We investigated whether chimeric antigen receptor (CAR) T-cells directed towards the disialoganglioside GD2 can represent a potentially more effective treatment with reduced long-term side effects. EXPERIMENTAL DESIGN: GD2 expression was evaluated on primary tumor biopsies of MB children by flow-cytometry. GD2 expression in MB cells was evaluated also in response to an EZH2 inhibitor (Tazemetostat). In in vitro, as well as in in vivo models, GD2+MB cells were targeted by a CAR-GD2.CD28.4-1BBζ (CAR.GD2)-T construct, including the suicide gene inducible-caspase-9. RESULTS: GD2 was expressed in 73.17% of MB tumors. The SHH and G4 subtypes expressed the highest levels of GD2, while the WNT subtype the lowest. In in-vitro co-culture assays, CAR.GD2 T-cells were able to kill GD2+MB cells. Pre-treatment with Tazemetostat upregulated GD2 expression, sensitizing GD2dimMB cells to CAR.GD2 T-cells cytotoxic activity. In orthotopic mouse models of MB, intravenously injected CAR.GD2 T-cells significantly controlled tumor growth, prolonging overall survival of treated mice. Moreover, the dimerizing drug AP1903 was able to cross the murine blood brain barrier and to eliminate both blood circulating and tumor infiltrating CAR.GD2 T-cells. CONCLUSIONS: Our experimental data indicate the feasibility of CAR.GD2 T-cell therapy. A phase I/II clinical trial will be conducted to evaluate the safety and therapeutic efficacy of CAR.GD2 therapy in high-risk MB patients.

Venetoclax plus cyclophosphamide and topotecan in heavily pre-treated relapsed metastatic neuroblastoma: a single center case series.

The prognosis of relapsed/refractory (R/R) neuroblastoma (NB) is dismal, calling for new therapeutic strategies. Venetoclax (VEN) is a highly selective, potent, orally bioavailable, BCL-2 inhibitor small-molecule that showed a synergistic effect with cyclophosphamide and topotecan (Cy-Topo) in murine NB models. Our aim was to evaluate the feasibility of VEN plus Cy-Topo in children with R/R NB. Four patients, who had previously failed > 3 lines of treatment, were treated with VEN plus Cy-Topo based on a 28-day schedule in an outpatient setting. BCL-2 expression in immunochemistry on tumor samples at relapse and the BCL2 gene status was evaluated in all patients. The main toxicity was hematological, with grade 4 neutropenia and thrombocytopenia occurring in all courses and leading to transient VEN discontinuation. Grade 3 oral mucositis was observed in 1/8 courses. No other grade 2-4 toxicities were observed. BCL-2 was expressed in all tumors, while no molecular abnormalities in the BCL-2 genes were detected. A stable disease was observed in all patients, without any progression during the study period. VEN plus Cy-Topo is well tolerated, with encouraging results that may be improved by testing the schedule in less advanced patients.

Neutralizing IFNγ improves safety without compromising efficacy of CAR-T cell therapy in B-cell malignancies.

Chimeric antigen receptor T (CAR-T) cell therapy may achieve long-lasting remission in patients with B-cell malignancies not responding to conventional therapies. However, potentially severe and hard-to-manage side effects, including cytokine release syndrome (CRS), neurotoxicity and macrophage activation syndrome, and the lack of pathophysiological experimental models limit the applicability and development of this form of therapy. Here we present a comprehensive humanized mouse model, by which we show that IFNγ neutralization by the clinically approved monoclonal antibody, emapalumab, mitigates severe toxicity related to CAR-T cell therapy. We demonstrate that emapalumab reduces the pro-inflammatory environment in the model, thus allowing control of severe CRS and preventing brain damage, characterized by multifocal hemorrhages. Importantly, our in vitro and in vivo experiments show that IFNγ inhibition does not affect the ability of CD19-targeting CAR-T (CAR.CD19-T) cells to eradicate CD19+ lymphoma cells. Thus, our study provides evidence that anti-IFNγ treatment might reduce immune related adverse effect without compromising therapeutic success and provides rationale for an emapalumab-CAR.CD19-T cell combination therapy in humans.

Allogeneic, donor-derived, second-generation, CD19-directed CAR-T cells for the treatment of pediatric relapsed/refractory BCP-ALL.

Autologous CD19-directed chimeric antigen receptor (CAR)-T cells have shown unprecedented efficacy in children with relapsed/refractory B-cell precursor acute lymphoblastic leukemia (BCP-ALL). However, patients either relapsing after allogeneic hematopoietic stem cell transplantation (allo-HSCT) or displaying profound lymphopenia and/or rapidly progressing disease often cannot access autologous products. These hurdles may be overcome by allogeneic, donor-derived CAR-T cells. We tested donor-derived T cells transduced with a second-generation (4.1BB) CD19-directed CAR for treatment of patients with BCP-ALL in a hospital-exemption setting. Two constructs were tested: a retroviral construct incorporating the suicide gene inducible caspase-9 (CD19-CAR-Retro_ALLO) first and then a lentiviral construct and an automated, Prodigy-based manufacturing process (CD19-CAR-Lenti_ALLO). Thirteen children/young adults received ALLO-CAR-T cells between March 2021 and October 2022. Doses ranged between 1.0 × 106 and 3.0 × 106 CAR-T cells per kg. The toxicity profile was comparable with that of autologous CAR-T cells, characterized mainly by cytopenia, cytokine release syndrome (maximum grade 1), and grade 2 immune-effector cell-associated neurotoxicity syndrome. One case of acute graft-versus-host disease (GVHD) occurred and was rapidly controlled with steroids and ruxolitinib. None of the other patients, including 3 given ALLO-CAR-T cells from an HLA-haploidentical donor, experienced GVHD. Two patients received ALLO-CAR-T cells before HSCT and showed a significant expansion of CAR-T cells without any sign of GVHD. All patients obtained complete remission (CR) with absence of minimal residual disease in the bone marrow. With a median follow-up of 12 months (range, 5-21), 8 of 13 patients maintained CR. Allogeneic anti-CD19 CAR-T cells can effectively treat highly refractory BCP-ALL relapsing after allo-HSCT without showing increased toxicity as compared with autologous CAR-T cells.

GD2-CART01 for Relapsed or Refractory High-Risk Neuroblastoma.

BACKGROUND: Immunotherapy with chimeric antigen receptor (CAR)-expressing T cells that target the disialoganglioside GD2 expressed on tumor cells may be a therapeutic option for patients with high-risk neuroblastoma. METHODS: In an academic, phase 1-2 clinical trial, we enrolled patients (1 to 25 years of age) with relapsed or refractory, high-risk neuroblastoma in order to test autologous, third-generation GD2-CAR T cells expressing the inducible caspase 9 suicide gene (GD2-CART01). RESULTS: A total of 27 children with heavily pretreated neuroblastoma (12 with refractory disease, 14 with relapsed disease, and 1 with a complete response at the end of first-line therapy) were enrolled and received GD2-CART01. No failure to generate GD2-CART01 was observed. Three dose levels were tested (3-, 6-, and 10×106 CAR-positive T cells per kilogram of body weight) in the phase 1 portion of the trial, and no dose-limiting toxic effects were recorded; the recommended dose for the phase 2 portion of the trial was 10×106 CAR-positive T cells per kilogram. Cytokine release syndrome occurred in 20 of 27 patients (74%) and was mild in 19 of 20 (95%). In 1 patient, the suicide gene was activated, with rapid elimination of GD2-CART01. GD2-targeted CAR T cells expanded in vivo and were detectable in peripheral blood in 26 of 27 patients up to 30 months after infusion (median persistence, 3 months; range, 1 to 30). Seventeen children had a response to the treatment (overall response, 63%); 9 patients had a complete response, and 8 had a partial response. Among the patients who received the recommended dose, the 3-year overall survival and event-free survival were 60% and 36%, respectively. CONCLUSIONS: The use of GD2-CART01 was feasible and safe in treating high-risk neuroblastoma. Treatment-related toxic effects developed, and the activation of the suicide gene controlled side effects. GD2-CART01 may have a sustained antitumor effect. (Funded by the Italian Medicines Agency and others; ClinicalTrials.gov number, NCT03373097.).

The peculiar challenge of bringing CAR-T cells into the brain: Perspectives in the clinical application to the treatment of pediatric central nervous system tumors.

Childhood malignant brain tumors remain a significant cause of death in the pediatric population, despite the use of aggressive multimodal treatments. New therapeutic approaches are urgently needed for these patients in order to improve prognosis, while reducing side effects and long-term sequelae of the treatment. Immunotherapy is an attractive option and, in particular, the use of gene-modified T cells expressing a chimeric antigen receptor (CAR-T cells) represents a promising approach. Major hurdles in the clinical application of this approach in neuro-oncology, however, exist. The peculiar location of brain tumors leads to both a difficulty of access to the tumor mass, shielded by the blood-brain barrier (BBB), and to an increased risk of potentially life-threatening neurotoxicity, due to the primary location of the disease in the CNS and the low intracranial volume reserve. There are no unequivocal data on the best way of CAR-T cell administration. Multiple trials exploring the use of CD19 CAR-T cells for hematologic malignancies proved that genetically engineered T cells can cross the BBB, suggesting that systemically administered CAR-T cell can be used in the neuro-oncology setting. Intrathecal and intra-tumoral delivery can be easily managed with local implantable devices, suitable also for a more precise neuro-monitoring. The identification of specific approaches of neuro-monitoring is of utmost importance in these patients. In the present review, we highlight the most relevant potential challenges associated with the application of CAR-T cell therapy in pediatric brain cancers, focusing on the evaluation of the best route of delivery, the peculiar risk of neurotoxicity and the related neuro-monitoring.

Human leukocyte antigen evolutionary divergence influences outcomes of paediatric patients and young adults affected by malignant disorders given allogeneic haematopoietic stem cell transplantation from unrelated donors.

High genetic heterogeneity in the human leukocyte antigen (HLA) increases the likelihood of efficient immune response to pathogens and tumours. As measure of HLA diversity, HLA evolutionary divergence (HED) has been shown to predict the response of tumours to immunotherapy and haematopoietic stem cell transplantation (HSCT) in adults. We retrospectively investigated the association of HED with outcomes of 153 paediatric/young adults patients, treated for malignant disorders with HSCT from 9-10/10 HLA-matched unrelated donors. HED was calculated as pairwise genetic distance between alleles in patient HLA-A, -B, -C, -DRB1, -DQB1 and -DPB1, using the locus median to stratify patients with 'high' or 'low' HED. Patients with high HED-B and -DRB1 showed significantly improved disease-free survival (DFS), especially when combined (70.8% vs 53.7% p = 0.008). High HED-B + -DRB1 was also associated with improved overall survival (OS) (82.1 vs 66.4% p = 0.014), and concomitant reduction of non-relapse-mortality (5.1% vs 21.1% p = 0.006). The impact on OS and DFS of combined HED-B + -DRB1 was confirmed in multivariate analysis [hazard ratio (HR) 0.39, p = 0.009; and HR 0.45, p = 0.007 respectively]. Only high HED scores for HLA-DPB1 were associated, in univariate analysis, with reduced incidence of relapse (15.9% vs 31.1%, p = 0.03). These results support HED as prognostic marker in allogeneic HSCT and, if confirmed in larger cohorts, would allow its use to inform clinical risk and potentially influence clinical practice.

Central Nervous System Metastasis in Neuroblastoma: From Three Decades Clinical Experience to New Considerations in the Immunotherapy Era.

Central nervous system (CNS) metastatic spread in neuroblastoma (NB) is rare and occurs more often at relapse/progression. We report on CNS involvement in high risk (HR) NB over 25 years. For this retrospective study, we reviewed the CNS imaging of all the patients treated at Bambino Gesù Children Hospital from 1 July 1996 to 30 June 2022. A total of 128 patients with HR NB were diagnosed over 26 years. Out of 128 patients, CNS metastatic spread occurred in 6 patients: 3 patients presented a metastatic spread at diagnosis, while in 3 patients, CNS was involved at relapse. Overall, the rate of occurrence of CNS spread is 4.7% with the same distribution at diagnosis and at relapse, namely 2.3%. Interestingly, CNS spread at diagnosis was observed only before 2012, whereas CNS was observed at relapse only after 2012, in the immunotherapy era. CNS metastases presented similar imaging features at diagnosis and at relapse, with a peculiar hemorrhagic aspect and mainly hemispheric localization in patients with bone skull involvement at the time of diagnosis. The outcome is dismal, and 3 out of 6 patients died for progressive disease.

The Pitfall of Ganglioneuroblastoma-Nodular Diagnosis: Clinical and Imaging Considerations over a Rare Bifocal Sporadic Case.

Neuroblastic tumors (NTs) represent the most common extracranial neoplasm occurring in childhood. Although ganglioneuroblastoma intermixed (GNBI) and ganglioneuroma (GN) are classified as very low-risk tumors, neuroblastoma (NB) and ganglioneuroblastoma-nodular (GNBN) may represent a serious risk to survival. Unfortunately, areas of GNBI and GNBN can coexist in the same mass, leading to incorrect risk staging when only biopsy is performed. Herein, we describe a case of multifocal NT (thoracic and abdominal localization) occurring in a 4-year-old male. Different histological subtypes, namely GNBI and GNBN, were revealed in the two lesions. We focus on the difficulties of proper diagnosis and risk stratification, underlining the usefulness of several diagnostic tools for appropriate management and therapeutic choices.

Safe and effective off-the-shelf immunotherapy based on CAR.CD123-NK cells for the treatment of acute myeloid leukaemia.

BACKGROUND: Paediatric acute myeloid leukaemia (AML) is characterized by poor outcomes in patients with relapsed/refractory disease, despite the improvements in intensive standard therapy. The leukaemic cells of paediatric AML patients show high expression of the CD123 antigen, and this finding provides the biological basis to target CD123 with the chimeric antigen receptor (CAR). However, CAR.CD123 therapy in AML is hampered by on-target off-tumour toxicity and a long "vein-to-vein" time. METHODS: We developed an off-the-shelf product based on allogeneic natural killer (NK) cells derived from the peripheral blood of healthy donors and engineered them to express a second-generation CAR targeting CD123 (CAR.CD123). RESULTS: CAR.CD123-NK cells showed significant anti-leukaemia activity not only in vitro against CD123+ AML cell lines and CD123+ primary blasts but also in two animal models of human AML-bearing immune-deficient mice. Data on anti-leukaemia activity were also corroborated by the quantification of inflammatory cytokines, namely granzyme B (Granz B), interferon gamma (IFN-γ) and tumour necrosis factor alpha (TNF-α), both in vitro and in the plasma of mice treated with CAR.CD123-NK cells. To evaluate and compare the on-target off-tumour effects of CAR.CD123-T and NK cells, we engrafted human haematopoietic cells (hHCs) in an immune-deficient mouse model. All mice infused with CAR.CD123-T cells died by Day 5, developing toxicity against primary human bone marrow (BM) cells with a decreased number of total hCD45+ cells and, in particular, of hCD34+CD38- stem cells. In contrast, treatment with CAR.CD123-NK cells was not associated with toxicity, and all mice were alive at the end of the experiments. Finally, in a mouse model engrafted with human endothelial tissues, we demonstrated that CAR.CD123-NK cells were characterized by negligible endothelial toxicity when compared to CAR.CD123-T cells. CONCLUSIONS: Our data indicate the feasibility of an innovative off-the-shelf therapeutic strategy based on CAR.CD123-NK cells, characterized by remarkable efficacy and an improved safety profile compared to CAR.CD123-T cells. These findings open a novel intriguing scenario not only for the treatment of refractory/resistant AML patients but also to further investigate the use of CAR-NK cells in other cancers characterized by highly difficult targeting with the most conventional T effector cells.

Post-Marketing Surveillance of CAR-T-Cell Therapies: Analysis of the FDA Adverse Event Reporting System (FAERS) Database.

INTRODUCTION: As chimeric antigen receptor T-cell therapies are becoming increasingly available in the armamentarium of the hematologist, there is an emerging need to monitor post-marketing safety. OBJECTIVE: We aimed to better characterize their safety profile by focusing on cytokine release syndrome and identifying emerging signals. METHODS: We queried the US Food and Drug Administration Adverse Event Reporting System (October 2017-September 2020) to analyze suspected adverse drug reactions to tisagenlecleucel (tisa-cel) and axicabtagene ciloleucel (axi-cel). Disproportionality analyses (reporting odds ratio) were performed by comparing chimeric antigen receptor T-cell therapies with (a) all other drugs (reference group 1) and (b) other onco-hematological drugs with a similar indication, irrespective of age (reference group 2), or (c) restricted to adults (reference group 3). Notoriety was assessed through package inserts and risk management plans. Adverse drug reaction time to onset and cytokine release syndrome features were investigated. RESULTS: Overall, 3225 reports (1793 axi-cel; 1433 tisa-cel) were identified. The reported toxicities were mainly: cytokine release syndrome (52.2%), febrile disorders (27.7%), and neurotoxicity (27.2%). Cytokine release syndrome and neurotoxicity were often co-reported and 75% of the events occurred in the first 10 days. Disproportionalities confirmed known adverse drug reactions and showed unexpected associations: for example, axi-cel with cardiomyopathies (reporting odds ratio = 2.3; 95% confidence interval 1.2-4.4) and gastrointestinal perforations (2.9; 1.2-7.3), tisa-cel with hepatotoxicity (2.5; 1.1-5.7) and pupil disorders (15.3; 6-39.1). CONCLUSIONS: Our study confirms the well-known adverse drug reactions and detects potentially emerging safety issues specific for each chimeric antigen receptor T-cell therapy, also providing insights into a stronger role for tisa-cel in inducing some immunodeficiency-related events (e.g., hypogammaglobulinemia, infections) and coagulopathies, and for axi-cel in neurotoxicity.

CAR-T Therapy for Pediatric High-Grade Gliomas: Peculiarities, Current Investigations and Future Strategies.

High-Grade Gliomas (HGG) are among the deadliest malignant tumors of central nervous system (CNS) in pediatrics. Despite aggressive multimodal treatment - including surgical resection, radiotherapy and chemotherapy - long-term prognosis of patients remains dismal with a 5-year survival rate less than 20%. Increased understanding of genetic and epigenetic features of pediatric HGGs (pHGGs) revealed important differences with adult gliomas, which need to be considered in order to identify innovative and more effective therapeutic approaches. Immunotherapy is based on different techniques aimed to redirect the patient own immune system to fight specifically cancer cells. In particular, T-lymphocytes can be genetically modified to express chimeric proteins, known as chimeric antigen receptors (CARs), targeting selected tumor-associated antigens (TAA). Disialoganglioside GD2 (GD-2) and B7-H3 are highly expressed on pHGGs and have been evaluated as possible targets in pediatric clinical trials, in addition to the antigens common to adult glioblastoma - such as interleukin-13 receptor alpha 2 (IL-13α2), human epidermal growth factor receptor 2 (HER-2) and erythropoietin-producing human hepatocellular carcinoma A2 receptor (EphA2). CAR-T therapy has shown promise in preclinical model of pHGGs but failed to achieve the same success obtained for hematological malignancies. Several limitations, including the immunosuppressive tumor microenvironment (TME), the heterogeneity in target antigen expression and the difficulty of accessing the tumor site, impair the efficacy of T-cells. pHGGs display an immunologically cold TME with poor T-cell infiltration and scarce immune surveillance. The secretion of immunosuppressive cytokines (TGF-ß, IL-10) and the presence of immune-suppressive cells - like tumor-associated macrophages/microglia (TAMs) and myeloid-derived suppressor cells (MDSCs) - limit the effectiveness of immune system to eradicate tumor cells. Innovative immunotherapeutic strategies are necessary to overcome these hurdles and improve ability of T-cells to eradicate tumor. In this review we describe the distinguishing features of HGGs of the pediatric population and of their TME, with a focus on the most promising CAR-T therapies overcoming these hurdles.

Brentuximab vedotin in combination with bendamustine in pediatric patients or young adults with relapsed or refractory Hodgkin lymphoma.

Although children and young adults with Hodgkin's lymphoma usually have a favorable prognosis, patients with primary refractory disease and some subsets of relapsed patients still have a dismal outcome. Brentuximab vedotin (BV) in combination with bendamustine may represent a suitable salvage therapy; data on 32 patients aged less than 25 years were retrospectively analyzed. Patients received up to six cycles of treatment of BV 1.8 mg/kg on day 1 and bendamustine 90-120 mg/m2 on days 2 and 3. At the end of treatment, the overall response rate was 81%. The 3-year overall and progression-free survivals are 78.1% and 67%, respectively.

Epigenetic Profiling and Response to CD19 Chimeric Antigen Receptor T-Cell Therapy in B-Cell Malignancies.

BACKGROUND: Chimeric antigen receptor (CAR) T cells directed against CD19 (CART19) are effective in B-cell malignancies, but little is known about the molecular factors predicting clinical outcome of CART19 therapy. The increasingly recognized relevance of epigenetic changes in cancer immunology prompted us to determine the impact of the DNA methylation profiles of CART19 cells on the clinical course. METHODS: We recruited 114 patients with B-cell malignancies, comprising 77 patients with acute lymphoblastic leukemia and 37 patients with non-Hodgkin lymphoma who were treated with CART19 cells. Using a comprehensive DNA methylation microarray, we determined the epigenomic changes that occur in the patient T cells upon transduction of the CAR vector. The effects of the identified DNA methylation sites on clinical response, cytokine release syndrome, immune effector cell-associated neurotoxicity syndrome, event-free survival, and overall survival were assessed. All statistical tests were 2-sided. RESULTS: We identified 984 genomic sites with differential DNA methylation between CAR-untransduced and CAR-transduced T cells before infusion into the patient. Eighteen of these distinct epigenetic loci were associated with complete response (CR), adjusting by multiple testing. Using the sites linked to CR, an epigenetic signature, referred to hereafter as the EPICART signature, was established in the initial discovery cohort (n = 79), which was associated with CR (Fisher exact test, P < .001) and enhanced event-free survival (hazard ratio [HR] = 0.36; 95% confidence interval [CI] = 0.19 to 0.70; P = .002; log-rank P = .003) and overall survival (HR = 0.45; 95% CI = 0.20 to 0.99; P = .047; log-rank P = .04;). Most important, the EPICART profile maintained its clinical course predictive value in the validation cohort (n = 35), where it was associated with CR (Fisher exact test, P < .001) and enhanced overall survival (HR = 0.31; 95% CI = 0.11 to 0.84; P = .02; log-rank P = .02). CONCLUSIONS: We show that the DNA methylation landscape of patient CART19 cells influences the efficacy of the cellular immunotherapy treatment in patients with B-cell malignancy.

TCRαß/CD19 depleted HSCT from an HLA-haploidentical relative to treat children with different nonmalignant disorders.

Several nonmalignant disorders (NMDs), either inherited or acquired, can be cured by allogeneic hematopoietic stem cell transplantation (HSCT). Between January 2012 and April 2020, 70 consecutive children affected by primary immunodeficiencies, inherited/acquired bone marrow failure syndromes, red blood cell disorders, or metabolic diseases, lacking a fully matched donor or requiring urgent transplantation underwent TCRαß/CD19-depleted haploidentical HSCT from an HLA-partially matched relative as part of a prospective study. The median age at transplant was 3.5 years (range 0.3-16.1); the median time from diagnosis to transplant was 10.5 months (2.7 for SCID patients). Primary engraftment was obtained in 51 patients, while 19 and 2 patients experienced either primary or secondary graft failure (GF), the overall incidence of this complication being 30.4%. Most GFs were observed in children with disease at risk for this complication (eg, aplastic anemia, thalassemia). All but 5 patients experiencing GF were successfully retransplanted. Six patients died of infectious complications (4 had active/recent infections at the time of HSCT), the cumulative incidence of transplant-related mortality (TRM) being 8.5%. Cumulative incidence of grade 1-2 acute GVHD was 14.4% (no patient developed grade 3-4 acute GVHD). Only one patient at risk developed mild chronic GVHD. With a median follow-up of 3.5 years, the 5-year probability of overall and disease-free survival was 91.4% and 86.8%, respectively. In conclusion, TCRαß/CD19-depleted haploidentical HSCT from an HLA-partially matched relative is confirmed to be an effective treatment of children with NMDs. Prompt donor availability, low incidence of GVHD, and TRM make this strategy an attractive option in NMDs patients. The study is registered at ClinicalTrial.gov as NCT01810120.