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Patients with precursor B-cell acute lymphoblastic leukemia (pB-ALL) who have relapsed after allogeneic hematopoietic stem cell transplantation (allo-HSCT), have relapsed more than once, or are resistant upfront have a dismal prognosis. CD19-targeted chimeric antigen receptor (CAR) T cells have evolved as potent immune therapies. Tisagenlecleucel (Tisa-cel) is a commercially available autologous CD19-directed CAR T-cell product. We performed a retrospective study inviting all CAR T-cell centers in Germany to participate. Eighty-one patients with pB-ALL were included. Twenty-eight days after CAR T-cell infusion, 71 patients (87.7%) were in complete response, and 8 (9.9%) were in nonremission. At 2 years, the probabilities of event-free survival (pEFS), relapse-free survival (pRFS), and overall survival (pOS) were 45.3%, 51.7%, and 53.2%, respectively. pEFS was not different in patients without (n = 16, 55.0%) vs with prior allo-HSCT (n = 65, 43.4%). In patients treated after allo-HSCT, the time to relapse after allo-HSCT was a strong predictor of outcome. Patients relapsing within 6 months of allo-HSCT had a disappointing pEFS of 18.4% (pOS = 16.0%); the pEFS for those relapsing later was 55.5% (pOS = 74.8%). Our study provides real-world experience in pediatric, adolescent, and young adult patients with ALL treated with Tisa-cel, where most patients were treated after having relapsed after allo-HSCT. A total of 45.3% were rescued with a single dose of Tisa-cel. Our novel finding that patients with ALL after allo-HSCT had by far a better pEFS if relapse occurred beyond 6 months might be helpful in clinical decision-making and motivates studies to uncover the reasons.

Allogeneic hematopoietic stem cell transplantation (HSCT) is the gold standard curative therapy for infants and children with many inborn errors of immunity (IEI), but adolescents and adults with IEI are rarely referred for transplant. Lack of published HSCT outcome data outside small, single-center studies and perceived high risk of transplant-related mortality have delayed the adoption of HSCT for IEI patients presenting or developing significant organ damage later in life. This large retrospective, multicenter HSCT outcome study reports on 329 IEI patients (age range, 15-62.5 years at HSCT). Patients underwent first HSCT between 2000 and 2019. Primary endpoints were overall survival (OS) and event-free survival (EFS). We also evaluated the influence of IEI-subgroup and IEI-specific risk factors at HSCT, including infections, bronchiectasis, colitis, malignancy, inflammatory lung disease, splenectomy, hepatic dysfunction, and systemic immunosuppression. At a median follow-up of 44.3 months, the estimated OS at 1 and 5 years post-HSCT for all patients was 78% and 71%, and EFS was 65% and 62%, respectively, with low rates of severe acute (8%) or extensive chronic (7%) graft-versus-host disease. On univariate analysis, OS and EFS were inferior in patients with primary antibody deficiency, bronchiectasis, prior splenectomy, hepatic comorbidity, and higher hematopoietic cell transplant comorbidity index scores. On multivariable analysis, EFS was inferior in those with a higher number of IEI-associated complications. Neither age nor donor had a significant effect on OS or EFS. We have identified age-independent risk factors for adverse outcome, providing much needed evidence to identify which patients are most likely to benefit from HSCT. ispartof: BLOOD vol:140 issue:14 pages:1635-1649 ispartof: location:United States status: published

Myeloproliferative disease; Paediatrics Enfermedad mieloproliferativa; Pediatría Malaltia mieloproliferativa; Pediatria Open Access funding enabled and organized by Projekt DEAL.

Total body irradiation (TBI)-based conditioning is associated with superior leukemia-free survival in children with ALL undergoing HSCT. However, the risk for subsequent malignant neoplasms (SMN) remains a significant concern. We analyzed 705 pediatric patients enrolled in the prospective ALL-SCT-BFM-2003 trial and its subsequent registry. Patients >2 years received conditioning with TBI 12 Gy/etoposide (n = 558) and children ≤2 years of age or with contraindications for TBI received busulfan/cyclophosphamide/etoposide (n = 110). The 5- and 10-year cumulative incidence of SMN was 0.02 ± 0.01 and 0.13 ± 0.03, respectively. In total, 39 SMN (34 solid tumors, 5 MDS/AML) were diagnosed in 33 patients at a median of 5.8 years (1.7–13.4), exclusively in the TBI group. Of 33 affected patients, 21 (64%) are alive at a median follow-up of 5.1 years (0–9.9) after diagnosis of their first SMN. In univariate analysis, neither age at HSCT, donor type, acute GVHD, chronic GVHD, nor CMV constituted a significant risk factor for SMN. The only significant risk factor was TBI versus non-TBI based conditioning. This analysis confirms and quantifies the increased risk of SMN in children with ALL after conditioning with TBI. Future strategies to avoid TBI will need careful tailoring within prospective, controlled studies to prevent unfavorable outcomes.

Deficiency of the transcription factor GATA2 is a highly penetrant genetic disorder predisposing to myelodysplastic syndromes (MDS) and immunodeficiency. It has been recognized as the most common cause underlying primary MDS in children. Triggered by the discovery of a recurrent synonymous GATA2 variant, we systematically investigated 911 patients with phenotype of pediatric MDS or cellular deficiencies for the presence of synonymous alterations in GATA2. In total, we identified nine individuals with five heterozygous synonymous mutations: c.351C>G, p.T117T (N = 4); c.649C>T, p.L217L; c.981G>A, p.G327G; c.1023C>T, p.A341A; and c.1416G>A, p.P472P (N = 2). They accounted for 8.2% (9/110) of cases with GATA2 deficiency in our cohort and resulted in selective loss of mutant RNA. While for the hotspot mutation (c.351C>G) a splicing error leading to RNA and protein reduction was identified, severe, likely late stage RNA loss without splicing disruption was found for other mutations. Finally, the synonymous mutations did not alter protein function or stability. In summary, synonymous GATA2 substitutions are a new common cause of GATA2 deficiency. These findings have broad implications for genetic counseling and pathogenic variant discovery in Mendelian disorders.

Summary Background The psychometric properties of an instrument, the Activity Scale for Kids-performance (ASKp), were assessed which was proposed to capture physical functioning after allogeneic hematopoietic stem cell transplantation (HSCT). Additionally, this multicenter observational prospective study investigated the influence of clinical correlates focusing on chronic graft-versus-host disease (cGVHD). Methods Patient-reported ASKp, clinician-reported Karnofsky/Lansky status (KPS/PSS), patient characteristics and cGVHD details were assessed of 55 patients with a median age of 12 years at baseline after day +100 post-HSCT and every 3 months during the next 18 months. The psychometric properties were evaluated and ASKp and KPS/PSS status was compared using ANOVAS and multiple regression models. Results The German version of the ASKp showed good psychometric properties except for ceiling effects. Discrimination ability of the ASKp was good regarding the need for devices but failed to predict cGVHD patients. Both the ASKp and the KPS/PSS were associated with patients after adoptive cell therapy being in need for devices, suffering from overlap cGVHD and from steroid side effects but not with patients’ age and gender. In contrast to the KPS/PSS the ASKp only showed significant differences after merging moderate and severe cGHVD patients when comparing them to No-cGVHD (F = 4.050; p = 0.049), being outperformed by the KPS/PSS (F = 20.082; p Conclusion The ASKp showed no clear advantages compared to KPS/PSS even though economical and patients’ effort was higher. Further application range may be limited through ceiling effects. Both should be taken into consideration. Therefore, the results may not support the usage of ASKp after HSCT and rather suggest KPS/PSS, both patient and clinician reported.

The GNE gene encodes an enzyme that initiates and regulates the biosynthesis of N-acetylneuraminic acid, a precursor of sialic acids. GNE mutations are classically associated with Nonaka myopathy and sialuria, following an autosomal recessive and autosomal dominant inheritance pattern. Reports show that single GNE variants cause severe thrombocytopenia without muscle weakness. Using panel sequencing, we identified two novel compound heterozygous variants in GNE in a young girl with life-threatening bleedings, severe congenital thrombocytopenia, and a platelet secretion defect. Both variants are located in the nucleotide-binding site of the N-acetylmannosamin kinase domain of GNE. Lectin array showed decreased α-2,3-sialylation on platelets, consistent with loss of sialic acid synthesis and indicative of rapid platelet clearance. Hematopoietic stem cell transplantation (HSCT) normalized platelet counts. This is the first report of an HSCT in a patient with an inherited GNE defect leading to normal platelet counts.

Diamond Blackfan anemia (DBA) is a rare congenital syndrome presenting primarily as pure red cell aplasia with constitutional abnormalities and cancer predisposition. Established treatment options are corticosteroids, regular erythrocyte transfusions with iron chelation therapy, and hematopoietic stem cell transplantation (HSCT). To date, HSCT is the only definitive curative treatment for the hematological phenotype of DBA, but there is little experience with its use. Given the rarity of the disease and its unique features, an expert panel agreed to draw up a set of recommendations on the use of HSCT in DBA to guide clinical decision-making and practice. The recommendations address indications, pretransplant patient evaluation, donor selection, stem cell sources, conditioning regimens, prophylaxis of rejection and graft versus host disease, and post-transplant follow-up.

Chronic granulomatous disease (CGD) is a primary immunodeficiency resulting in life-threatening infections and inflammatory complications. Allogeneic hematopoietic cell transplantation (allo-HCT) can cure the disease, but the indication to transplant remains controversial. We performed a retrospective multicenter study of 712 patients with CGD who underwent allo-HCT transplantation from March 1993 through December 2018. We studied 635 children (aged 1 antigen mismatch. Choice of conditioning regimen did not influence OS or EFS. In summary, we report an excellent outcome after allo-HCT in CGD, with low incidence of graft failure and mortality in all ages. Older patients and recipients of 1-antigen-mismatched grafts had a less favorable outcome. Transplantation should be strongly considered at a younger age and particularly in the presence of a well-matched donor.

Pediatric allogeneic hematopoietic cell transplantation (HCT) practices differ from those of adults, particularly the heterogeneity of transplantable nonmalignant diseases and the lower incidence of graft-versus-host disease (GVHD). Several guidelines regarding the management of acute (a) GVHD in adult HCT have been published. We aimed to capture the real-life approaches for pediatric aGVHD prophylaxis/treatment, and data from 75/193 (response rate 39%) EBMT centers (26 countries) were included, representing half (48%) of the pediatric EBMT-HCT activity. Results with >= 75% approval from respondents (74/75) for GVHD prophylaxis after myeloablative HCT for malignancies partially contradict published guidelines: Single-agent cyclosporine A (CsA) was used for matched sibling donor HCT in 47%; blood CsA levels were reported lower; the relapse risk in malignant diseases influenced GVHD prophylaxis with early withdrawal of CsA; distinct longer duration of CsA was employed in nonmalignant diseases. Most centers used additional anti-thymocyte globulin for matched unrelated and mismatched donor HCT, but not for matched siblings. Regarding prophylaxis in nonmyeloablative conditioning (mainly for nonmalignant diseases), responses showed broad heterogeneity. High conformity was found for first-line treatment; however, results regarding steroid-refractory aGVHD indicate an earlier diagnosis in children. Our findings highlight the need for standardized pediatric approaches toward aGVHD prophylaxis/treatment differentiated for malignant and nonmalignant underlying diseases.

Diamond-Blackfan anemia (DBA) is a congenital pure red cell aplasia associated with congenital abnormalities and cancer predisposition. Allogeneic hematopoietic stem cell transplantation (HSCT) can correct the hematological phenotype and is indicated in transfusion-dependent patients. In 70 children reported to the German DBA and French HSCT registries, HSCT was performed from 1985 to 2017. Median age at HSCT was 5.5 years (range, 0.9-17.3 years). Two-thirds of patients (64%) were transplanted from a matched sibling donor (MSD), and most procedures were performed after the year 1999 (73%). Primary engraftment was achieved in all patients. One patient developed secondary graft failure. Cumulative incidence of acute graft-versus-host disease (GVHD) was 24% for II-IV (95% confidence interval [CI], 16% to 37%) and 7% for III-IV (95% CI, 3% to 17%); cumulative incidence of chronic GVHD was 11% (95% CI, 5% to 22%). The probability of chronic GVHDfree survival (cGFS) was 87% (95% CI, 79% to 95%) and significantly improved over time (, SCOPUS: ar.j, info:eu-repo/semantics/published

AML SCT-BFM 2007 was the first hematopoietic stem cell transplantation (HCT) trial in Germany to comply with the European Clinical Trials Directive, and aimed to standardize pediatric HCT for acute myeloid leukemia (AML) across centers in Germany, Austria, and the Czech Republic. Children with high-risk features and a good early response achieving a complete first remission (CR-1) and those in CR-2 after a first relapse were stratified to receive HCT from a matched donor after myeloablative conditioning consisting of busulfan, cyclophosphamide, and melphalan. Four-year EFS and OS were 61 and 70%. Cumulative incidence of relapse (CIR) was 22%. TRM was 15% and correlated with age reaching 9% (SE 3%) in children younger than 12 years and 31% (SE 9%) in older children and adolescents. Children with poorly responding primary disease or relapse were allocated to receive early HCT after a cytoreductive regimen with fludarabine, amsacrine, and cytarabine, followed by reduced intensity conditioning and prophylactic donor lymphocyte infusions. Four-year EFS and OS were 49 and 53%. CIR was 38% and TRM 11%. For patients with primary poor response disease, early use of RIC HCT followed by prophylactic DLI can induce long-term remissions in more than 50% (EFS 46% (SE 9%)).

Survival in children with relapsed/refractory a cute myeloid leukemia is unsatisfactory. Treatment consists of one course of fludarabine, cytarabine and liposomal daunorubicin, followed by fludarabine and cytarabine and stem-cell transplantation. Study ITCC 020/I-BFM 2009-02 aimed to identify the recommended phase II dose of clofarabine replacing fludarabine in the abovementioned combination regimen (3+3 design). Escalating dose levels of clofarabine (20-40 mg/m²/day x 5 days) and liposomal daunorubicin (40-80 mg/m²/day) were administered with cytarabine (2 g/m²/day x 5 days). Liposomal DNR was given on day 1, 3 and 5 only. The cohort at the recommended phase II dose was expanded to make a preliminary assessment of anti-leukemic activity. Thirty-four children were enrolled: refractory 1st (n=11), early 1st (n=15), ≥2ⁿd relapse (n=8). Dose level 3 (30 mg/m² clofarabine; 60 mg/m² liposomal daunorubicin) appeared to be safe only in patients without subclinical fungal infections. Infectious complications were dose-limiting. The recommended phase II dose was 40 mg/m² clofarabine with 60 mg/m² liposomal daunorubicin. Side-effects mainly consisted of infections. The overall response rate was 68% in 31 response evaluable patients, and 80% at the recommended phase II dose (n=10); 22 patients proceeded to stem cell transplantation. The 2-year probability of event-free survival (pEFS) was 26.5±7.6 and probability of survival (pOS) 32.4±8.0%. In the 21 responding patients, the 2-year pEFS was 42.9±10.8 and pOS 47.6±10.9%. Clofarabine expo-sure in plasma was not significantly different from that in single-agent studies. In conclusion, clofarabine was well tolerated and showed high response rates in relapsed/refractory pediatric acute myeloid leukemia. Patients with (sub)clinical fungal infections should be treated with caution. Clofarabine has been taken forward in the Berlin-Frankfurt-Münster study for newly diagnosed acute myeloid leukemia. The Study ITCC-020 was registered as EUDRA-CT 2009-009457-13; Dutch Trial Registry number 1880. CA extern

Familial myelodysplastic syndromes arise from haploinsufficiency of genes involved in hematopoiesis and are primarily associated with early-onset disease. Here we describe a familial syndrome in seven patients from four unrelated pedigrees presenting with myelodysplastic syndrome and loss of chromosome 7/7q. Their median age at diagnosis was 2.1 years (range, 1-42). All patients presented with thrombocytopenia with or without additional cytopenias and a hypocellular marrow without an increase of blasts. Genomic studies identified constitutional mutations (p.H880Q, p.R986H, p.R986C and p.V1512M) in the SAMD9L gene on 7q21, with decreased allele frequency in hematopoiesis. The non-random loss of mutated SAMD9L alleles was attained via monosomy 7, deletion 7q, UPD7q, or acquired truncating SAMD9L variants p.R1188X and p.S1317RfsX21. Incomplete penetrance was noted in 30% (3/10) of mutation carriers. Long-term observation revealed divergent outcomes with either progression to leukemia and/or accumulation of driver mutations (n=2), persistent monosomy 7 (n=4), and transient monosomy 7 followed by spontaneous recovery with SAMD9L-wildtype UPD7q (n=2). Dysmorphic features or neurological symptoms were absent in our patients, pointing to the notion that myelodysplasia with monosomy 7 can be a sole manifestation of SAMD9L disease. Collectively, our results define a new subtype of familial myelodysplastic syndrome and provide an explanation for the phenomenon of transient monosomy 7. Registered at: www.clinicaltrials.gov; #NCT00047268.

Introduction: MLN-eo associated with gene rearrangements of PDGFRA, PDGFRB, FGFR1, or PCM1-JAK2 are rare haematological neoplasms primarily affecting adults. Eosinophilia commonly occurs but may also be absent. The heterogeneous clinical picture and the rarity of the disease, especially in children, may delay an early diagnosis. MLN-eo are characterized by constitutive tyrosine kinase activity due to gene fusions. It is thus of prognostic importance to obtain a prompt genetic diagnosis to start a specific therapy. Here we report two female paediatric cases of MLN-eo (6 months and 13 years old at initial diagnosis). Methods: In both cases, bone marrow morphology, karyotyping, fluorescence in-situ hybridization analysis (FISH) via break apart probes (PDGFRB (5q32), FGFR1 (8p12), JAK2 (9p24), FIP1L1/CHIC2/PDGFRA (4q12)), targeted RNA sequencing and in one case array CGH were performed. Results: The 6 months old girl was admitted to hospital with a 3-month history of rash and leukocytosis with eosinophilia. The skin showed multiple purpuric lesions (Fig 1 A/B). Mild splenomegaly was noted. White blood count (WBC) was 48000/µl with 38% eosinophils. Bone marrow trephine showed hypercellular marrow with mild fibrosis and eosinophilia without increase in blasts. Biopsy of a skin nodule displayed a histological pattern of interface dermatitis with eosinophilic infiltrate. (Fig 1 C/D). Fluorescence R-banding showed a normal karyotype (46,XX) (Fig. 2 A). However, FISH and array CGH detected an interstitial deletion of 5` PDGFRB (5q32) in 61 % of interphase nuclei (Fig. 2 B-D). Targeted RNA sequencing (RNA-seq) confirmed, as the array CGH suggested, the suspected TNIP1/PDGFRB fusion. According to the WHO criteria, diagnosis of a myeloid neoplasia with PDGFRB rearrangement due to an interstitial deletion in 5q was made. Because of the PDGFRB rearrangement, imatinib (250 mg/m²/d) therapy was started. Leukocyte and eosinophil counts normalized within 4 days without signs of tumour lysis. Skin lesions disappeared within 2 weeks. After 4 weeks, the dose was reduced to 100 mg/m² 3 x/week. Now at 14 months of age, peripheral counts continue to be normal and the fusion transcript is not detectable in the peripheral blood. The 13 years old girl was admitted with severe tachypnoea due to pleural effusions, hepatosplenomegaly and lymphadenopathy. Echocardiography showed endocarditis, left ventricular fibrosis and mitral insufficiency. WBC was 112170 /µL with 39% eosinophils. Bone marrow aspirate and trephine showed a feature of myeloproliferative neoplasia (MPN) with eosinophilia. The karyotype was normal. A rearrangement involving the FGFR1 locus was detected by FISH (Fig. 3 B/C). Splitting of the probe signals indicated an inversion on chromosome 8. Targeted RNA sequencing revealed a PCM1-FGFR1 fusion transcript. Diagnosis of a MLN-eo with FGFR1 rearrangement and evidence of a PCM1-FGFR1 fusion, most likely caused by an inversion on chromosome 8, was made. The girl stabilized after therapy with prednisone, vincristine, hydroxycarbamide and anti-IL-5 antibody. Peripheral blood counts normalized within 2 weeks. Eight weeks after initial diagnosis she presented with signs of a transient ischemic attack, respiratory distress and arterial hypotension. At that time WBC was 139000/µl with 53% myeloid blasts and 5% eosinophils. Trisomy 8 was detected in all metaphases and 88% of cells in FISH (Fig.3 A-C). Diagnosis of a progression to a myeloid blast phase was made. Induction chemotherapy (cytarabine, idarubicin, etoposidphosphate) was administered. On day +22 bone marrow aspirates showed the persisting picture of MPN. Preparations for hematopoietic stem cell transplantation (HSCT) and ponatinib therapy were begun, but cardiac and respiratory insufficiency that developed during chemotherapy were fatal. Conclusion: As these two cases have shown, standard cytogenetic and molecular methods may not be sufficient to diagnose MLN-eo due to cytogenetically cryptic aberrations. Thus, genetic diagnosis must be precise and quick (e.g. break apart FISH, targeted RNA-seq) in order to initiate adequate therapies with tyrosine kinase inhibitors or HSCT. Patients with rearrangements of PDGFRA or PDGFRB usually respond well to imatinib, whereas patients with FGFR1 and JAK2 gene fusions exhibit more aggressive diseases with variable sensitivity to tyrosine kinase inhibitors and have an early indication for HSCT. Figure 1 Figure 1. Disclosures Reiter: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel expenses, Research Funding; Blueprint Medicines: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel expenses; Incyte: Membership on an entity's Board of Directors or advisory committees, Other: Travel expenses; AOP Orphan Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support; Deciphera: Membership on an entity's Board of Directors or advisory committees, Other: Travel expenses; Abbvie: Membership on an entity's Board of Directors or advisory committees; Celgene/BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: travel support.

Poster-Abstract