HLA-haploidentical stem cell transplantation in children with inherited bone marrow failure syndromes: A retrospective analysis on behalf of EBMT severe aplastic Anemia and pediatric diseases working parties.

Haploidentical stem cell transplantation (haplo-SCT) represents the main alternative for children with inherited bone marrow failure syndrome (I-BMF) lacking a matched donor. This retrospective study, conducted on behalf of the EBMT SAAWP and PDWP, aims to report the current outcomes of haplo-SCT in I-BMFs, comparing the different in vivo and ex vivo T-cell depletion approaches. One hundred and sixty-two I-BMF patients who underwent haplo-SCT (median age 7.4 years) have been registered. Fanconi Anemia was the most represented diagnosis (70.1%). Based on different T-cell depletion (TCD) approaches, four categories were identified: (1) TCRαß+/CD19+-depletion (43.8%); (2) T-repleted with post-transplant Cyclophosphamide (PTCy, 34.0%); (3) In-vivo T-depletion with ATG/alemtuzumab (14.8%); (4) CD34+ positive selection (7.4%). The cumulative incidences (CI) of neutrophil and platelet engraftment were 84% and 76% respectively, while that of primary and secondary graft failure was 10% and 8% respectively. The 100-day CI of acute GvHD grade III-IV(95% CI) was 13%, while the 24-month CI of extensive chronic GvHD was 4%. After a median follow-up of 43.4 months, the 2-year overall survival(OS) and GvHD/Rejection-free Survival (GRFS) probabilities are 67% and 53%, respectively. The TCR CD3+αß+/CD19+ depletion group showed a significantly lower incidence of both acute and chronic GvHD and higher OS (79%; p0.013) and GRFS (71%; p < .001), while no significant differences in outcomes have been observed by different diagnosis and conditioning regimens. This large retrospective study supports the safety and feasibility of haplo-SCT in I-BMF patients. TCRαß+/CD19+ depletion offers higher chances of patients' survival, with a significantly lower risk of severe a- and c-GvHD in I-BMFs compared to other platforms.

Cytogenetic abnormalities predict survival after allogeneic hematopoietic stem cell transplantation for pediatric acute myeloid leukemia: a PDWP/EBMT study.

Poor-risk (PR) cytogenetic/molecular abnormalities generally direct pediatric patients with acute myeloid leukemia (AML) to allogeneic hematopoietic stem cell transplant (HSCT). We assessed the predictive value of cytogenetic risk classification at diagnosis with respect to post-HSCT outcomes in pediatric patients. Patients younger than 18 years at the time of their first allogeneic HSCT for AML in CR1 between 2005 and 2022 who were reported to the European Society for Blood and Marrow Transplantation registry were subgrouped into four categories. Of the 845 pediatric patients included in this study, 36% had an 11q23 abnormality, 24% had monosomy 7/del7q or monosomy 5/del5q, 24% had a complex or monosomal karyotype, and 16% had other PR cytogenetic abnormalities. In a multivariable model, 11q23 (hazard ratio [HR] = 0.66, P = 0.03) and other PR cytogenetic abnormalities (HR = 0.55, P = 0.02) were associated with significantly better overall survival when compared with monosomy 7/del7q or monosomy 5/del5q. Patients with other PR cytogenetic abnormalities had a lower risk of disease relapse after HSCT (HR = 0.49, P = 0.01) and, hence, better leukemia-free survival (HR = 0.55, P = 0.01). Therefore, we conclude that PR cytogenetic abnormalities at diagnosis predict overall survival after HSCT for AML in pediatric patients.

Feasibility of peripheral blood stem cell collection from sickle cell trait donors with an intensified G-CSF regimen.

OBJECTIVES: Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative treatment for SCD and bone marrow from an HLA-matched sibling is currently the standard of care. Haploidentical HSCT from a family donor with a TCR αß/CD19 depleted graft (T-haplo) is an increasingly successful alternative, which requires the generation of G-CSF stimulated peripheral stem cell (PBSC) from haploidentical relatives. These sickle cell trait (SCT) donors reported to develop SCD-related complications in conditions of severe stress. METHODS: In this retrospective analysis, we compared the safety and efficacy of PBSC mobilization with a G-CSF intensified mobilization regimen in SCT donors with a conventional G-CSF mobilization regimen in healthy donors. RESULTS: The reported adverse events were similar during intensified G-CSF mobilization, apheresis, and shortly after stem cell apheresis in SCT and control donors. In SCT and control donors, we were able to mobilize high yields of CD34+ stem cells and the harvested CD34+ cell count was comparable with control donors. CONCLUSIONS: Peripheral stem cell mobilization using an intensified G-CSF regimen is safe, and well tolerated among SCT donors. SCT donors are a valid alternative for collection of peripheral CD34+ stem cells for T-cell-depleted haploidentical stem cell transplantation.

Heparanase wildtype is associated with a reduced incidence of transplant-associated systemic vasculopathies.

Some of the early complications of hematopoietic stem cell transplantation (HSCT) concerning the small vessels can be summarized as transplant-associated systemic vasculopathies (TASV). One enzyme known to play a major role in inflammation, tissue remodeling, and repair processes as well as tumor metastasis is heparanase (HPSE). HPSE genetic variants have recently been associated with significant influence on the risk of developing certain TASV such as a sinusoidal obstruction syndrome. This study aimed to validate the two known HPSE single nucleotide polymorphisms (SNPs)-rs4693608 and rs4364254-as a genetic predictor of TASV in a cohort of 494 patients and were correlated retrospectively with the clinical course post-HSCT. Significant association was revealed for rs4364254, showing that the incidence of TASV (38.0% vs. 57.8%, p = .009) and in particular of acute graft-versus-host disease (aGvHD) (36.3% vs. 54.0%, p = .0138) was lower in wildtype CC carriers than in TC/TT carriers. Moreover, compared with all other genotypes, the allelic combination GG-CC had the lowest incidence of TASV (34.9% vs. 57.4%, p = .0109) and aGvHD in particular (34.9% vs. 53.5%, p = .0315). A competing risk regression analysis confirmed a significantly reduced risk for a TASV in patients with GG (subhazard ratio [SHR] = 0.670, p = .043) and CC (SHR = 0.598, p = .041) compared with the corresponding homozygote SNP as well as for allelic combinations correlated with low HPSE gene expression (SHR = 0.630, p = .016) and in correlation with clinical risk factors. In summary, our study emphasizes an association of HPSE gene SNPs with TASV, in particular with aGvHD, which could be implementable as pre-transplant risk stratification if validated prospectively.

Transcranial Doppler sonography and the effect of haematopoietic stem cell transplantation in sickle cell disease.

BACKGROUND: Sickle cell disease (SCD) is one of the most prevalent monogenetic diseases worldwide and one of the most serious complications is stroke. Transcranial Doppler (TCD) demonstrated to be highly predictive for an imminent stroke by measuring blood flow velocities in the basal cerebral arteries. Currently, the only curative therapy for SCD is hematopoietic stem cell transplantation (HSCT). The aim of this study is to verify the correlation between blood flow velocities and stroke including the effect of HSCT. METHODS: In our retrospective single-center study a total of 26 sickle cell patients (HbSS, HbSß+-thalassemia, HbSSα-thalassemia minima, HbSSα-thalassemia minor and HbSC) were analyzed between 2010 and 2016. The highest time averaged maximum mean blood flow velocity (TAMMV) measured was documented and evaluated with respect to SCD genotype and effect of HSCT. Acute and symptomatic as well as silent strokes were recorded as separate parameters. RESULTS: In our study, ten patients had normal blood flow velocities before HSCT (six HbSS and four HbSß+-thalassemia patients) and 13 patients presented with abnormal TCD (eight HbSS, three HbSSα-thalassemia minima, one HbSSα-thalassemia minor and one HbSC). Thirteen of 26 study participants (ten HbSS and three HbSß+-thalassemia patients) received HSCT. In two patients, TAMMV in basal cerebral arteries remained "normal", in one they remained conditional and in one TAMMV was reduced to normal. Four of 26 study participants (15.4%), including all patients with HbSS genotype, presented with a stroke, but none had "abnormal" TAMMV with TCD performed after the onset of stroke in each case. At the time we performed the TCD, the patients had already suffered the stroke. CONCLUSION: In our study, none of the patients with stroke displayed abnormal blood flow velocities in TCD. Yet, HSCT at this stage of the disease still had a positive effect on TAMMV. Further studies are needed whether this effect converts into reduced stroke risk at all or only selected SCD patients undergoing HSCT.

Busulfan-fludarabine- or treosulfan-fludarabine-based myeloablative conditioning for children with thalassemia major.

Significant advances in supportive care for patients with transfusion-dependent thalassemia major (TDT) have improved patients' life expectancy. However, transfusion-associated iron overload remains a significant barrier to long-term survival with good quality of life. Today, allogeneic hematopoietic stem cell transplantation (HSCT) is the current curative standard of care. Alongside selection of the best available donor, an optimized conditioning regimen is crucial to maximize outcomes for patients with TDT undergoing HSCT. The aim of this retrospective analysis was to investigate the role of busulfan-fludarabine-based and treosulfan-fludarabine-based conditioning in TDT patients undergoing HSCT. We included 772 patients registered in the European Society for Blood and Marrow Transplantation (EBMT) database who underwent first HSCT between 2010 and 2018. Four hundred ten patients received busulfan-fludarabine-based conditioning (median age 8.6 years) and 362 patients received treosulfan-fludarabine-based conditioning (median age 5.7 years). Patient outcomes were retrospectively compared by conditioning regimen. Two-year overall survival was 92.7% (95% confidence interval: 89.3-95.1%) after busulfan-fludarabine-based conditioning and 94.7% (95% confidence interval: 91.7-96.6%) after treosulfan-fludarabine-based conditioning. There was a very low incidence of second HSCT overall. The main causes of death were infections, graft-versus-host disease, and rejection. In conclusion, use of busulfan or treosulfan as the backbone of myeloablative conditioning for patients with TDT undergoing HSCT resulted in comparably high cure rates. Long-term follow-up studies are warranted to address the important issues of organ toxicities and gonadal function.

T-Cell-Replete Versus ex vivo T-Cell-Depleted Haploidentical Haematopoietic Stem Cell Transplantation in Children With Acute Lymphoblastic Leukaemia and Other Haematological Malignancies.

Allogeneic haematopoietic stem cell transplantation (HSCT) represents a potentially curative option for children with high-risk or refractory/relapsed leukaemias. Traditional donor hierarchy favours a human leukocyte antigen (HLA)-matched sibling donor (MSD) over an HLA-matched unrelated donor (MUD), followed by alternative donors such as haploidentical donors or unrelated cord blood. However, haploidentical HSCT (hHSCT) may be entailed with significant advantages: besides a potentially increased graft-vs.-leukaemia effect, the immediate availability of a relative as well as the possibility of a second donation for additional cellular therapies may impact on outcome. The key question in hHSCT is how, and how deeply, to deplete donor T-cells. More T cells in the graft confer faster immune reconstitution with consecutively lower infection rates, however, greater numbers of T-cells might be associated with higher rates of graft-vs.-host disease (GvHD). Two different methods for reduction of alloreactivity have been established: in vivo T-cell suppression and ex vivo T-cell depletion (TCD). Ex vivo TCD of the graft uses either positive selection or negative depletion of graft cells before infusion. In contrast, T-cell-repleted grafts consisting of non-manipulated bone marrow or peripheral blood grafts require intense in vivo GvHD prophylaxis. There are two major T-cell replete protocols: one is based on post-transplantation cyclophosphamide (PTCy), while the other is based on anti-thymocyte globulin (ATG; Beijing protocol). Published data do not show an unequivocal benefit for one of these three platforms in terms of overall survival, non-relapse mortality or disease recurrence. In this review, we discuss the pros and cons of these three different approaches to hHSCT with an emphasis on the significance of the existing data for children with acute lymphoblastic leukaemia.

Matched Family Donor Lymphocyte Infusions as First Cellular Therapy for Patients with Severe Primary T Cell Deficiencies.

Patients with primary immunodeficiencies caused by severe defects in T cell immunity are at risk of acquiring life-threatening infections. Cellular therapies are necessary to establish normal T cell function and to allow for long-term survival. This is most commonly achieved by hematopoietic stem cell transplantation (HSCT), but the outcome of this procedure is impaired if active infections are present at the time of HSCT. Donor lymphocyte infusions (DLIs) are a well-established therapeutic strategy following HSCT to treat viral infections, improve donor cell engraftment, or achieve graft-versus-leukemia activity in malignant disease. Here we present a cohort of 6 patients with primary T cell deficiencies who received transfusions of unselected mature donor lymphocytes prior and not directly related to allogeneic HSCT. DLIs obtained from the peripheral blood of HLA-identical (10/10) family donors were transfused without prior conditioning to treat or prevent life-threatening infections. All patients are alive with a follow-up of 0.5 to 16.5 years after the initial T cell administration. Additional cellular therapies were administered in 5 of 6 patients at 0.8 to 15 months after the first DLI. Mild cutaneous graft-versus-host disease (GVHD, stage ≤2) was observed in 3 of 6 patients and resolved spontaneously. We provide evidence that unselected HLA-identical DLIs can effectively prevent or contribute to overcome infections with a limited risk for GVHD in T cell deficient patients. The T cell system established by this readily available source can provide T cell function for years and can serve as a bridge to additional cellular therapies or, in specific conditions, as definite treatment.

Setting up and sustaining blood and marrow transplant services for children in middle-income economies: an experience-driven position paper on behalf of the EBMT PDWP.

Severe blood disorders and cancer are the leading cause of death and disability from noncommunicable diseases in the global pediatric population and a major financial burden. The most frequent of these conditions, namely sickle cell disease and severe thalassemia, are highly curable by blood or bone marrow transplantation (BMT) which can restore a normal health-related quality of life and be cost-effective. This position paper summarizes critical issues in extending global access to BMT based on ground experience in the start-up of several BMT units in middle-income countries (MICs) across South-East Asia and the Middle East where close to 700 allogeneic BMTs have been performed over a 10-year period. Basic requirements in terms of support systems, equipment, and consumables are summarized keeping in mind WHO's model essential lists and recommendations. BMT unit setup and maintenance costs are summarized as well as those per transplant. Low-risk BMT is feasible and safe in MICs with outcomes comparable to high-income countries but at a fraction of the cost. This report might be of assistance to health care institutions in MICs interested in developing hematopoietic stem cell transplantation services and strengthening context appropriate tertiary care and higher medical education.

Alternative donor: αß/CD19 T-cell-depleted haploidentical hematopoietic stem cell transplantation for sickle cell disease.

Sickle cell disease (SCD) is an inherited disorder; despite significant improvements in supportive care, SCD continues to cause substantial morbidity, mortality, and reduced life expectancy. Allogeneic hematopoietic stem cell transplantation (HSCT) is currently the only widely available curative therapy for SCD, which is offered as a standard of care for patients with a matched sibling donor (MSD). Donor availability is limited to a minority of patients. Thus, αß/CD3-depleted haploidentical HSCT, as an efficient means for depletion of graft-versus-host disease (GvHD)-mediating T cells, can be offered as an alternative curative therapy, particularly for nonmalignant diseases such as SCD. Out of 38 patients with advanced stage SCD, 25 were transplanted with CD3/CD19- or T-cell receptor αß/CD19 T-cell-depleted peripheral stem cell grafts (T-haplo-HSCT group), whereas 13 transplanted from MSD (MSD group); both groups received an almost identical conditioning regimen. Engraftment was achieved in all. However, in the T-haplo-HSCT group, three patients succumbed to an uncontrolled cytomegalovirus pneumonitis, a macrophage activation syndrome, and a major blood group incompatibility with a late graft failure and multiorgan failure. The overall survival was 88% and 100% in T-haplo-HSCT and MSD groups, respectively. None of our patients developed a Glucksberg Grade III-IV acute GvHD. Four patients (16%) in the T-haplo-HSCT group and two patients (15%) in the MSD group developed a steroid-sensitive, mild-to-moderate chronic GvHD that resolved within 18 months posttransplant. These results are encouraging and demonstrate the feasibility, safety, and efficacy of T-haplo-HSCT in advanced stage SCD in children and adults, thus offering a curative alternative to majority of patients.

Diagnosis, grading, and treatment recommendations for children, adolescents, and young adults with sinusoidal obstructive syndrome: an international expert position statement.

Sinusoidal obstructive syndrome, also known as hepatic veno-occlusive disease, is a potentially life-threatening complication that occurs in children undergoing haemopoietic stem-cell transplantation (HSCT). Differences in the incidence of genetic predisposition and clinical presentation of sinusoidal obstructive syndrome between children and adults have rendered the historical Baltimore and Seattle diagnostic criteria insufficient for children. In 2017, the European Society for Blood and Marrow Transplantation (EBMT) proposed the first paediatric diagnostic and severity grading guidelines for sinusoidal obstructive syndrome, intended for implementation across European centres. However, universally accepted paediatric criteria are needed to ensure prompt diagnosis, definitive treatment, and improved outcomes for children, adolescents, and young adults with sinusoidal obstructive syndrome, and to facilitate international clinical research collaboration. We convened an international panel of multidisciplinary experts including physicians with expertise in HSCT, paediatric intensive care, nephrology, hepatology, radiology, pathology, and transfusion medicine; HSCT advanced-practice providers and medical trainees; pharmacists; and translational and basic science researchers from the Pediatric Acute Lung Injury and Sepsis Investigators Network, the EBMT, the Pediatric Blood and Marrow Transplant Consortia, and several other institutions with extensive experience in sinusoidal obstructive syndrome. Panellists convened at The University of Texas, MD Anderson Cancer Center (Houston, TX, USA) in February, 2019, to evaluate the available evidence. In this expert position statement paper, we provide consensus recommendations for the international implementation of guidelines for the diagnosis, severity grading, and treatment of sinusoidal obstructive syndrome among children, adolescents, and young adults. We endorse universal adoption of paediatric diagnostic guidelines for sinusoidal obstruction syndrome as proposed by the EBMT, and provide implementation guidance for standardisation across centres; we have further proposed adjunctive use of age-appropriate organ-specific toxicity criteria for severity grading and provided prophylaxis and treatment considerations among children and adolescent and young adult patients. Key recommendations include: (1) liver biopsy, portal venous wedge pressure, and reversal of portal venous flow on Doppler ultrasonography should not be used for the routine diagnosis of sinusoidal obstructive syndrome in children, adolescents, and young adults; (2) platelet refractoriness can be defined as a corrected count increment of less than 5000-7500 following at least two sequential ABO-compatible fresh platelet transfusions; (3) hepatomegaly is best defined as an absolute increase of at least 1 cm in liver length at the midclavicular line; and if a baseline measurement is not available, hepatomegaly can be defined as greater than 2 SDs above normal for age; and (4) the presence and volume of ascites can be categorised as mild (minimal fluid by liver, spleen, or pelvis), moderate (<1 cm fluid), or severe (fluid in all three regions with >1 cm fluid in at least two regions).

Emerging targeted therapies for pediatric acute myeloid leukemia.

Acute myeloid leukemia is a heterogeneous group of diseases accounting for 15-20% of all tumors diagnosed in children under 15 years of age. The past few decades have yielded remarkable improvements in long-term outcomes for children with acute myeloid leukemia. A better risk-group stratification of patients based upon clinical and biologic features, a more effective use of anti-leukemic agents and enormous improvements in supportive care have increased the probability of cure by approximately 60%. The increase in our understanding of the biology of this disease has resulted in the development of molecularly targeted therapies that are potentially more effective and less toxic than the standard approaches. We here review novel molecularly targeted drugs for the treatment of childhood acute myeloid leukemia such as monoclonal antibodies, inhibitors of signalling molecules, proteasome inhibitors and epigenetic agents. For these recently patented agents, we also provide a detailed analysis of the published preclinical data and the clinical trials that have been completed.

Focal nodular hyperplasia of the liver after intensive treatment for pediatric cancer: is hematopoietic stem cell transplantation a risk factor?

Focal nodular hyperplasia (FNH) is a benign hepatic lesion very rarely described in the pediatric population. It has been reported more frequently in patients treated for pediatric cancers with chemotherapy or hematopoietic stem cell transplantation. The use of high dosage of alkylating agents, the occurrence of venous occlusive disease, graft-versus-host disease, and other variables linked to the hematopoietic stem cell transplantation procedure can represent risk factors for the development of FNH in the pediatric age. The discovery of hepatic nodules in the follow-up of patients treated for malignancies suggests recurrence of disease and raises a diagnostic dilemma. Here we describe possible risk factors, clinical and radiological findings of eight pediatric patients who developed focal nodular hyperplasia after hematopoietic stem cell transplantation. The aim of this report is to provide useful diagnostic tools to facilitate accurate diagnosis of FNH and suggest a correct management of this benign lesion during postcancer follow-up.

Comparing dynamic parameters of tumor vascularization in nude mice revealed by magnetic resonance imaging and contrast-enhanced intermittent power Doppler sonography.

RATIONALE: Angiogenesis is essential for spread and growth of malignant tumors. Because noninvasive methods for observing tumor vascularization are limited, most of previous results were based on histologic findings alone. In this study, dynamic parameters obtained using intermittent contrast-enhanced Doppler sonography and dynamic MRI were compared and correlated with microvessel density. METHODS: Eleven tumor-bearing nude mice were examined with dynamic T(1)-weighted sequences using Gd-DTPA in a 1.5 T magnetic resonance (MR) scanner and with intermittent power Doppler sonography after a single bolus of galactose based contrast agent. After examination 6 tumors were harvested for immunofluorescence microscopy using a CD31 stain. Using a 2-compartment model, the MR parameters amplitude (reflecting plasma volume) and k(ep) (influenced by the vessel permeability) were calculated and compared with maximal enhancement (max) and perfusion P measured with ultrasound. RESULTS: The MR amplitude correlated with the ultrasound parameter max significantly (r = 0.61; P = 0.01). Max (r = 0.67; P = 0.01), amplitude (r = 0.72; P = 0.01), and perfusion (r = 0.62; P = 0.05) correlated with the microvessel density. k(ep) moderately correlated with max, but not with perfusion and microvessel density. CONCLUSIONS: Dynamic MRI and contrast enhanced ultrasound are supplementing methods for examining perfusion and vascularity of experimental tumors.