Efficacy and safety of azacitidine in pediatric patients with newly diagnosed advanced myelodysplastic syndromes before hematopoietic stem cell transplantation in the AZA-JMML-001 trial.

Here we report efficacy, pharmacokinetics, and safety data obtained in treatment-naive, pediatric patients with newly diagnosed advanced MDS receiving azacitidine in the AZA-JMML-001 study. The primary endpoint was response rate (proportion of patients with complete response [CR], partial response [PR], or marrow CR, sustained for ≥4 weeks). Of the 10 patients enrolled, one had an unconfirmed marrow CR and none had confirmed responses after three cycles; the study was therefore closed after stage 1. Azacitidine was well tolerated. The lack of efficacy of azacitidine in pediatric patients with newly diagnosed advanced MDS highlights the need for effective new treatments in these patients.

Diagnostic yield of bone marrow aspiration in paediatric primary immune thrombocytopenia: impact of evolution and adherence to medical guidelines over the last 25 years.

The aim of this study is to analyse the diagnostic value of bone marrow aspiration (BMA) in a retrospective cohort of patients with suspected immune thrombocytopaenia (ITP). We further measure changes in the percentage of patients who underwent this study and whether testing or not was in accordance with current guidelines at the time of diagnosis. We conducted a chart review of 243 patients with ITP who underwent follow-up in our institution between 1995 and 2022. The patients were divided into historical cohorts based on the practice guidelines of the Spanish Society of Pediatric Hematology and Oncology (SEHOP) and the American Society of Hematology (ASH) in place at the time of follow-up. For each case, time of disease presentation or initial diagnosis was defined as that which occurred in the first 72 h following disease onset. Based on data from the historical cohorts studied, we observed a lower total number of BMAs at diagnosis over time (p < 0.005). A gradual reduction was seen in the number of BMAs with the introduction of guidelines, including a progressively lower number of BMAs performed without indication (p < 0.05). Subsequent to the initial diagnosis, the procedure played a decisive role in only 2 patients (0.58%), allowing for a diagnosis of acquired aplastic anaemia in both cases. In both of them on diagnosis, BMA did not appear to be indicated, although subsequent analysis after 72 h raised suspicion of bone marrow failure. CONCLUSION: BMA at presentation did not significantly alter the diagnosis in our cohort of patients with an initial suspicion of ITP, although the procedure was decisive in diagnosing 2 cases of acquired aplastic anaemia during the subsequent course of the disease. Regarding the number of aspirations performed, our findings show that increased physician compliance with current guidelines reduced the rate of unnecessary BMAs. WHAT IS KNOWN: • BMA is a supplementary test for the diagnosis of ITP. • The usefulness of this invasive diagnostic procedure is not clearly stated in current guidelines. WHAT IS NEW: • Adjustments to scientific guidelines have led to a reduction in the number of BMAs performed on our patients with suspected ITP in the last 27 years. • While the risks and benefits of BMA at the time of diagnosis are unclear in patients with suspected ITP, the procedure does not contribute significant information to support the diagnosis.

Inborn Error of STAT2-Dependent IFN-I Immunity in a Patient Presented with Hemophagocytic Lymphohistiocytosis and Multisystem Inflammatory Syndrome in Children.

Human inborn errors of immunity (IEI) affecting the type I interferon (IFN-I) induction pathway have been associated with predisposition to severe viral infections. Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening systemic hyperinflammatory syndrome that has been increasingly associated with inborn errors of IFN-I-mediated innate immunity. Here is reported a novel case of complete deficiency of STAT2 in a 3-year-old child that presented with typical features of HLH after mumps, measles, and rubella vaccination at the age of 12 months. Due to the life-threatening risk of viral infection, she received SARS-CoV-2 mRNA vaccination. Unfortunately, she developed multisystem inflammatory syndrome in children (MIS-C) after SARS-CoV-2 infection, 4 months after the last dose. Functional studies showed an impaired IFN-I-induced response and a defective IFNα expression at later stages of STAT2 pathway induction. These results suggest a possible more complex mechanism for hyperinflammatory reactions in this type of patients involving a possible defect in the IFN-I production. Understanding the cellular and molecular links between IFN-I-induced signaling and hyperinflammatory syndromes can be critical for the diagnosis and tailored management of these patients with predisposition to severe viral infection.

Emapalumab in Children with Primary Hemophagocytic Lymphohistiocytosis.

BACKGROUND: Primary hemophagocytic lymphohistiocytosis is a rare syndrome characterized by immune dysregulation and hyperinflammation. It typically manifests in infancy and is associated with high mortality. METHODS: We investigated the efficacy and safety of emapalumab (a human anti-interferon-γ antibody), administered with dexamethasone, in an open-label, single-group, phase 2-3 study involving patients who had received conventional therapy before enrollment (previously treated patients) and previously untreated patients who were 18 years of age or younger and had primary hemophagocytic lymphohistiocytosis. The patients could enter a long-term follow-up study until 1 year after allogeneic hematopoietic stem-cell transplantation or until 1 year after the last dose of emapalumab, if transplantation was not performed. The planned 8-week treatment period could be shortened or extended if needed according to the timing of transplantation. The primary efficacy end point was the overall response, which was assessed in the previously treated patients according to objective clinical and laboratory criteria. RESULTS: At the cutoff date of July 20, 2017, a total of 34 patients (27 previously treated patients and 7 previously untreated patients) had received emapalumab; 26 patients completed the study. A total of 63% of the previously treated patients and 65% of the patients who received an emapalumab infusion had a response; these percentages were significantly higher than the prespecified null hypothesis of 40% (P = 0.02 and P = 0.005, respectively). In the previously treated group, 70% of the patients were able to proceed to transplantation, as were 65% of the patients who received emapalumab. At the last observation, 74% of the previously treated patients and 71% of the patients who received emapalumab were alive. Emapalumab was not associated with any organ toxicity. Severe infections developed in 10 patients during emapalumab treatment. Emapalumab was discontinued in 1 patient because of disseminated histoplasmosis. CONCLUSIONS: Emapalumab was an efficacious targeted therapy for patients with primary hemophagocytic lymphohistiocytosis. (Funded by NovImmune and the European Commission; NI-0501-04 and NI-0501-05 ClinicalTrials.gov numbers, NCT01818492 and NCT02069899.).

Gene therapy restores the transcriptional program of hematopoietic stem cells in Fanconi anemia.

Clinical trials have shown that lentiviral-mediated gene therapy can ameliorate bone marrow failure (BMF) in nonconditioned Fanconi anemia (FA) patients resulting from the proliferative advantage of corrected FA hematopoietic stem and progenitor cells (HSPC). However, it is not yet known if gene therapy can revert affected molecular pathways in diseased HSPC. Single-cell RNA sequencing was performed in chimeric populations of corrected and uncorrected HSPC co-existing in the BM of gene therapy-treated FA patients. Our study demonstrates that gene therapy reverts the transcriptional signature of FA HSPC, which then resemble the transcriptional program of healthy donor HSPC. This includes a down-regulated expression of TGF-ß and p21, typically up-regulated in FA HSPC, and upregulation of DNA damage response and telomere maintenance pathways. Our results show for the first time the potential of gene therapy to rescue defects in the HSPC transcriptional program from patients with inherited diseases; in this case, in FA characterized by BMF and cancer predisposition.

Extracorporeal photopheresis in paediatric patients: A retrospective comparison between different 'off-line' protocols.

BACKGROUND AND OBJECTIVES: Extracorporeal photopheresis (ECP) has been shown to be an effective treatment for graft-versus-host disease (GvHD). However, information regarding lymphocyte collection for ECP in children is limited. The aim of this study was to analyse and compare lymphocyte collection for ECP in children using different devices and protocols. Moreover, we have studied both safety and variables of the infused product related to treatment efficacy. PATIENTS AND METHODS: This was a retrospective study of 91 patients who underwent 1524 apheresis procedures with either the COBE Spectra or Spectra Optia system. The comparison study between the Optia protocols (MNC and CMNC) was prioritized. We analysed 578 procedures using the Optia blood cell separator: 204 and 374 using the MNC and the CMNC protocol, respectively. RESULTS: The Optia CMNC protocol showed better collection efficiency, with increased lymphocyte collection per kg of body weight (p < 0.001). On multivariate analysis, the type of protocol showed no relationship with haematocrit or platelet loss. Most procedures were well-tolerated, with the most frequent adverse events related to venous access (21.7%). Seventy-one percent of patients had either partial or complete clinical GvHD response. In the multivariate model, only two variables were associated with a better response to ECP, younger age and a greater increase of B lymphocytes after treatment. CONCLUSION: Lymphocyte collection for ECP is well-tolerated in most children, achieving complete or partial response in more than half of GvHD patients. CMNC is the optimal software to perform lymphocyte collection in children.

Mobilization with high-dose granulocyte colony-stimulating factor alone at 12 µg/kg twice a day in high-risk pediatric patients: A retrospective analysis of the experience in a single center.

INTRODUCTION: Mobilization regimes in pediatric patients at high risk for poor mobilization are not standardized across different institutions. We present a retrospective analysis of our experience with a high-dose granulocyte colony-stimulating factor (G-CSF) regime of 12 µg/Kg per body weight (BW) twice a day for 4 days used in high-risk patients. MATERIAL AND METHODS: We report the results of all pediatric patients mobilized with high-dose G-CSF between January 1999 and February 2021 in our center. A successful mobilization was defined as a peripheral blood (PB) CD34+ cell count of ≥10 CD34+ cells/µl on the fifth day of mobilization immediately before leukapheresis. A minimum cell yield of ≥2 × 106 CD34+ cells/Kg of BW was required for a successful collection. RESULTS: Of the 262 patients included in the analysis, mobilization failure was found in 27 (10.3%). In a univariate analysis, this was associated with age, weight, baseline diagnosis, and having undergone a previous mobilization cycle, the latter being the only factor that remained significantly associated in a multivariate analysis (P = 0.03). The 54 patients (20.6%) did not reach the minimum required CD34+ cell yield. 50.4% of the patients reported adverse events (AEs) during the mobilization period, and 23 (9.1%) reported 3 or more concomitant AEs. However, all of them were mild and did not affect the mobilization schedule. CONCLUSIONS: Although most high-risk pediatric patients are successfully mobilized with the high-dose G-CSF regime, this approach does not salvage all of them and significantly increases the presence of AEs in comparison to standard-dose regimes.

Natural gene therapy by reverse mosaicism leads to improved hematology in Fanconi anemia patients.

Fanconi anemia (FA) is characterized by chromosome fragility, bone marrow failure (BMF) and predisposition to cancer. As reverse genetic mosaicism has been described as "natural gene therapy" in patients with FA, we sought to evaluate the clinical course of a cohort of FA mosaic patients followed at referral centers in Spain over a 30-year period. This cohort includes patients with a majority of T cells without chromosomal aberrations in the DEB-chromosomal breakage test. Relative to non-mosaic FA patients, we observed a higher proportion of adult patients in the cohort of mosaics, with a later age of hematologic onset and a milder evolution of (BMF). Consequently, the requirement for hematopoietic stem cell transplant (HSCT) was also lower. Additional studies allowed us to identify a sub-cohort of mosaic FA patients in whom the reversion was present in bone marrow (BM) progenitor cells leading to multilineage mosaicism. These multilineage mosaic patients are older, have a lower percentage of aberrant cells, have more stable hematology and none of them developed leukemia or myelodysplastic syndrome when compared to non-mosaics. In conclusion, our data indicate that reverse mosaicism is a good prognostic factor in FA and is associated with more favorable long-term clinical outcomes.

Haplo-identical or mismatched unrelated donor hematopoietic cell transplantation for Fanconi anemia: Results from the Severe Aplastic Anemia Working Party of the EBMT.

Allogeneic hematopoietic cell transplantation (HCT) is the only curative option for bone marrow failure or hematopoietic malignant diseases for Fanconi anemia (FA) patients. Although results have improved over the last decades, reaching more than 90% survival when a human leukocyte antigen (HLA)-identical donor is available, alternative HCT donors are still less reported. We compared HCT outcomes using HLA-mismatched unrelated donors (MMUD; n = 123) or haplo-identical donors (HDs), either using only in vivo T cell depletion (n = 33) or T cells depleted in vivo with some type of graft manipulation ex vivo (n = 59) performed for FA between 2000 and 2018. Overall survival (OS) by 24 months was 62% (53-71%) for MMUD, versus 80% (66-95%) for HDs with only in vivo T cell depletion and 60% (47-73%) for HDs with in vivo and ex vivo T cell depletion (p = .22). Event-free survival (EFS) was better for HD-transplanted FA patients with only in vivo T cell depletion 86% (73-99%) than for those transplanted from a MMUD 58% (48-68%) or those with graft manipulation 56% (42-69%) (p = .046). Grade II-IV acute graft-versus-host disease (GVHD) was 41% (MMUD) versus 40% (HDs with no graft manipulation) versus 17% (HDs with T cell depleted graft), (p = .005). No differences were found for the other transplant related outcomes. These data suggest that HDs might be considered as an alternative option for FA patients with better EFS using unmanipulated grafts.

Plerixafor-based mobilization in pediatric healthy donors with unfavorable donor/recipient body weight ratio resulted in a better CD34+ collection yield: A retrospective analysis.

INTRODUCTION: In order to propose risk-adapted mobilization algorithms, several authors have tried to look for predictive factors of the CD34+ yield in healthy pediatric donors. Donor recipient body weight ratio (D/R ratio) was identified as one of the main variables related with the success to achieve the target cell dose for transplantation. According to this variable we modified the mobilization schedule. MATERIAL AND METHODS: We report the results of 46 mobilizations and apheresis procedures performed in our center with unfavorable D/R ratio. Mobilization was attempted by the standard regime of G-CSF (10 mcg/kg/24 hours) in 28 cases (60.9%), with high dose G-CSF (10 mcg/kg/12 hours) in 9 cases (19.6%), and with plerixafor and G-CSF single dose regime in 9 cases (19.6%). RESULTS: CD34+ cell quantification before apheresis is closely related to CD34+ yield, being the only factor related to collected CD34+ cells (beta .71; P < .0001). The mobilization efficiency was higher in plerixafor group compared to the other two schedules (P < .0001). By using plerixafor for mobilization, we achieved the target CD34+ cell dose of ≥2 × 106 /kg per recipient body weight in all cases with unfavorable D/R ratio. It was observed that 17.4% of cases that not reached the established target cell dose were located in the standard or high-dose mobilization regimes. This difference is even greater for optimal collections (≥5 × 106 /kg), since of the 54.3% cases that did not reach this goal none was mobilized by plerixafor. CONCLUSION: Tailoring the mobilization regime we can reach the target cell dose, even in those cases with the worst D/R ratio.

Secondary immune thrombocytopenia in children: Characteristics and outcome of a large cohort from two Spanish centres.

AIM: To evaluate the incidence and outcome of secondary immune thrombocytopenia (ITP) in a large cohort of paediatric Spanish patients. METHODS: A retrospective observational study was conducted in two paediatric University hospitals in Spain between 2009 and 2019, which included children from 4 months to 18 years old diagnosed with ITP. Data were recorded from clinical charts: gender, age at diagnosis, coexisting condition and associated characteristics, outcome and treatment. RESULTS: Secondary ITP was diagnosed in 87 out of 442 patients (19.6%). Post-immunisation ITP was seen in younger children. The onset of secondary ITP to autoimmune diseases (AD) and immunodeficiencies (ID) was at an older age and had more tendency to be insidious, and platelet level was higher than primary ITP. Mean time from ITP onset to AD diseases or ID diagnosis was 1.2 and 2.6 years, respectively. Whereas the cumulative incidence of remission was significantly higher in post-immunisation and post-viral infection (compared with primary ITP patients), it was worse in AD and ID patients. CONCLUSIONS: Identification of secondary ITP is important as it predicts outcome. Most of them are diagnosed at ITP onset, but AD diseases and ID should be ruled out periodically as they are usually identified later.

Engraftment and in vivo proliferation advantage of gene-corrected mobilized CD34+ cells from Fanconi anemia patients.

Previous Fanconi anemia (FA) gene therapy studies have failed to demonstrate engraftment of gene-corrected hematopoietic stem and progenitor cells (HSPCs) from FA patients, either after autologous transplantation or infusion into immunodeficient mice. In this study, we demonstrate that a validated short transduction protocol of G-CSF plus plerixafor-mobilized CD34+ cells from FA-A patients with a therapeutic FANCA-lentiviral vector corrects the phenotype of in vitro cultured hematopoietic progenitor cells. Transplantation of transduced FA CD34+ cells into immunodeficient mice resulted in reproducible engraftment of myeloid, lymphoid, and CD34+ cells. Importantly, a marked increase in the proportion of phenotypically corrected, patient-derived hematopoietic cells was observed after transplantation with respect to the infused CD34+ graft, indicating the proliferative advantage of corrected FA-A hematopoietic repopulating cells. Our data demonstrate for the first time that optimized protocols of hematopoietic stem cell collection from FA patients, followed by the short and clinically validated transduction of these cells with a therapeutic lentiviral vector, results in the generation of phenotypically corrected HSPCs capable of repopulating and developing proliferation advantage in immunodeficient mice. Our results suggest that clinical approaches for FA gene therapy similar to those used in this study will facilitate hematopoietic repopulation in FA patients with gene corrected HSPCs, opening new prospects for gene therapy of FA patients.

Outcome of haematopoietic stem cell transplantation in dyskeratosis congenita.

Dyskeratosis congenita (DC) is a genetic multisystem disorder with frequent involvement of the bone marrow. Haematopoietic stem cell transplantation (HSCT) is the only definitive cure to restore haematopoiesis, even though it cannot correct other organ dysfunctions. We collected data on the outcome of HSCT in the largest cohort of DC (n = 94) patients ever studied. Overall survival (OS) and event-free survival (EFS) at 3 years after HSCT were 66% and 62%, respectively. Multivariate analysis showed better outcomes in patients aged less than 20 years and in patients transplanted from a matched, rather than a mismatched, donor. OS and EFS curves tended to decline over time. Early lethal events were infections, whereas organ damage and secondary malignancies appeared afterwards, even a decade after HSCT. A non-myeloablative conditioning regimen appeared to be most advisable. Organ impairment present before HSCT seemed to favour the development of chronic graft-versus-host disease and T-B immune deficiency appeared to enhance pulmonary fibrosis. According to the present data, HSCT in DC is indicated in cases of progressive marrow failure, whereas in patients with pre-existing organ damage, this should be carefully evaluated. Further efforts to investigate treatment alternatives to HSCT should be encouraged.

Hemiparesis in an Adolescent With Acute Lymphoblastic Leukemia: Everything Is Not Always What it Seems.

Acute lymphoblastic leukemia is a common malignancy in childhood. Managing adverse events during treatment can result in very complex situations. A previously healthy adolescent diagnosed with T-cell acute lymphoblastic leukemia developed on day +55 of induction chemotherapy hemiparesis, dysesthesia, and facial palsy. Blood tests and brain imaging techniques were unremarkable. The patient was diagnosed with a conversion disorder, which completely resolved. Although rare in clinical practice, children and adolescents with cancer do not always have organic pathology explaining their symptoms. Psychiatric disorders such as those of the somatoform spectrum must be considered, particularly in patients with anxiety or depression.

Immunomagnetic T Cell Depletion: an Analysis of Variables Affecting Final Cell Yield.

BACKGROUND: Only little detailed information has been published by a small number of centers on experiences with the technical aspects of "in vitro" large-scale graft manipulation technologies. METHODS: We report our experiences with the graft engineering procedures performed and the results obtained after T cell depletion. We have analyzed data from 212 procedures (108 CD34+ cell selection and 104 CD3+/CD19+ cell depletion). RESULTS: We conclude that the final cell products after selection or depletion were completely different with regard to CD34+ cell purity (95.8% vs. 1.52%). The CD34+ cell recovery after CD34+ cell selection is negatively affected when the initial leukocyte and/or CD34+ cell counts exceed the threshold defined by the manufacturer (68.9% vs. 45.2%, p < 0.01). However, the cell count threshold defined for the depletion technique could be exceeded without seriously affecting final results (86.1% vs. 86.4% for those with more or less than 40 x 109 leukocyte before the procedure; p = 0.7). Another important conclusion from this study is that in both CD34+ cell selection and CD3+/CD19+ cell depletion better results were reached after having gained experience by performing the procedures several times. This means that a learning process can be expected when using these in vitro graft manipulation procedures. CONCLUSIONS: It is extremely important to have experienced staff to perform these procedures. The expected results are different with each procedure so the decision on which of these T cell depletion approaches are used should be based on the characteristics of the final product wanted.

A phase I/II trial of interleukin-15--stimulated natural killer cell infusion after haplo-identical stem cell transplantation for pediatric refractory solid tumors.

BACKGROUND AIMS: Preliminary data suggest that T-cell-depleted haplo-identical stem cell transplantation (haplo-SCT) has a clinically beneficial allograft-versus-tumor effect associated with natural killer (NK) cell immune reconstitution. METHODS: This phase I/II trial descriptively evaluates the feasibility of interleukin (IL)-15-stimulated NK cell infusion after haplo-SCT in pediatric patients with refractory solid tumors. RESULTS: Six patients received an IL-15-stimulated NK cell infusion at 30 days after haplo-SCT. The mean number of infused NK cells per product was 11.3 × 10(6)/kg (range, 3-27 × 10(6)/kg). The T-cell count was <1 × 10(3)/kg in all patients (range, 0-0.75 × 10(3)/kg). No toxic effects related to IL-15--stimulated NK cell infusion were observed. Four of the six patients showed a clinical response (one achieved very good partial remission, two achieved partial remission and one had stable disease). One patient had progressive disease, and the response was not evaluated in the remaining patient. After a median follow-up period of 310 days, all patients had died: four of cancer relapse, one of cancer-associated thrombotic micro-angiopathy and one of acute graft-versus-host disease. CONCLUSIONS: The adoptive transfer of allogeneic IL-15--stimulated NK cells might be feasible and safe in heavily pretreated pediatric patients with refractory solid tumors, though the advanced stage of disease and toxic effects of haplo-SCT may limit the efficacy of NK cell infusion in this population.