Karim Kentouche

Reduced-intensity conditioning and HLA-matched haemopoietic stem-cell transplantation in patients with chronic granulomatous disease: a prospective multicentre study

BACKGROUND In chronic granulomatous disease allogeneic haemopoietic stem-cell transplantation (HSCT) in adolescents and young adults and patients with high-risk disease is complicated by graft-failure, graft-versus-host disease (GVHD), and transplant-related mortality. We examined the effect of a reduced-intensity conditioning regimen designed to enhance myeloid engraftment and reduce organ toxicity in these patients. METHODS This prospective study was done at 16 centres in ten countries worldwide. Patients aged 0-40 years with chronic granulomatous disease were assessed and enrolled at the discretion of individual centres. Reduced-intensity conditioning consisted of high-dose fludarabine (30 mg/m(2) [infants <9 kg 1·2 mg/kg]; one dose per day on days -8 to -3), serotherapy (anti-thymocyte globulin [10 mg/kg, one dose per day on days -4 to -1; or thymoglobuline 2·5 mg/kg, one dose per day on days -5 to -3]; or low-dose alemtuzumab [<1 mg/kg on days -8 to -6]), and low-dose (50-72% of myeloablative dose) or targeted busulfan administration (recommended cumulative area under the curve: 45-65 mg/L × h). Busulfan was administered mainly intravenously and exceptionally orally from days -5 to -3. Intravenous busulfan was dosed according to weight-based recommendations and was administered in most centres (ten) twice daily over 4 h. Unmanipulated bone marrow or peripheral blood stem cells from HLA-matched related-donors or HLA-9/10 or HLA-10/10 matched unrelated-donors were infused. The primary endpoints were overall survival and event-free survival (EFS), probabilities of overall survival and EFS at 2 years, incidence of acute and chronic GVHD, achievement of at least 90% myeloid donor chimerism, and incidence of graft failure after at least 6 months of follow-up. FINDINGS 56 patients (median age 12·7 years; IQR 6·8-17·3) with chronic granulomatous disease were enrolled from June 15, 2003, to Dec 15, 2012. 42 patients (75%) had high-risk features (ie, intractable infections and autoinflammation), 25 (45%) were adolescents and young adults (age 14-39 years). 21 HLA-matched related-donor and 35 HLA-matched unrelated-donor transplants were done. Median time to engraftment was 19 days (IQR 16-22) for neutrophils and 21 days (IQR 16-25) for platelets. At median follow-up of 21 months (IQR 13-35) overall survival was 93% (52 of 56) and EFS was 89% (50 of 56). The 2-year probability of overall survival was 96% (95% CI 86·46-99·09) and of EFS was 91% (79·78-96·17). Graft-failure occurred in 5% (three of 56) of patients. The cumulative incidence of acute GVHD of grade III-IV was 4% (two of 56) and of chronic graft-versus-host disease was 7% (four of 56). Stable (≥90%) myeloid donor chimerism was documented in 52 (93%) surviving patients. INTERPRETATION This reduced-intensity conditioning regimen is safe and efficacious in high-risk patients with chronic granulomatous disease. FUNDING None.

Inflammation-associated ADAMTS13 deficiency promotes formation of ultra-large von Willebrand factor

The findings of this study suggest that systemic inflammation results in ADAMTS13 deficiency, and thereby activates hemostasis. In a prospective, longitudinal study, we investigated the association between decreased ADAMTS13 activity and impaired hemostasis, as well as organ dysfunctions in patients with systemic inflammation due to extracorporeal cardiopulmonary circuit or with severe sepsis. Similar to negative acute phase proteins, ADAMTS13 activity declined stepwise according to the extent of inflammatory responses. A marked imbalance between ADAMTS13 activity and VWF antigen level was associated with the appearance of ultra-large VWF multimers in plasma, with organ dysfunction and lethality. Our data support the view that systemic inflammation results in an ADAMTS13 deficiency which activates hemostasis.

Remission of thrombotic thrombocytopenic purpura in a patient with compound heterozygous deficiency of von Willebrand factor-cleaving protease by infusion of solvent/detergent plasma

Plasma exchange or plasma infusion is considered to be the therapy of choice in patients with thrombotic thrombocytopenic purpura (TTP) who are deficient in von Willebrand factor‐cleaving protease (VWF‐CP). Recently, mutations in the ADAMTS13 gene were identified as being responsible for VWF‐CP deficiency in patients with familial TTP (VWF‐CP deficiency in the absence of an inhibitor). Here we report on a girl who presented with recurrent thrombocytopenia and anaemia since birth, developing the full pentad of characteristic TTP at the age of 16y. Congenital TTP was confirmed on the basis of severe VWF‐CP deficiency in the absence of an acquired inhibitor. The patient was found to be compound heterozygous for two hitherto undescribed mutations in the ADAMTS13 gene: a truncating frame shift mutation, 4143insA in exon 29, and the nonsense mutation 3100A > T in exon 24 (R1034X). After infusion of solvent/detergent plasma, the patient went into remission and remained asymptomatic under regular plasma therapy at 2‐wk intervals for over two years.

Malignancy‐associated haemophagocytic lymphohistiocytosis in children and adolescents

Haemophagocytic lymphohistiocytosis (HLH) in the context of malignancy is mainly considered a challenge of adult haematology. While this association is also observed in children, little is known regarding inciting factors, appropriate treatment and prognosis. We retrospectively analysed 29 paediatric and adolescent patients for presenting features, type of neoplasm or preceding chemotherapy, treatment and outcome. Haemophagocytic lymphohistiocytosis was considered triggered by the malignancy (M‐HLH) in 21 patients, most of whom had T‐ (n = 12) or B‐cell neoplasms (n = 7), with Epstein–Barr virus as a co‐trigger in five patients. In eight patients, HLH occurred during chemotherapy (Ch‐HLH) for malignancy, mainly acute leukaemias (n = 7); an infectious trigger was found in seven. In M‐ and Ch‐HLH, median overall survival was 1·2 and 0·9 years, and the 6 month survival rates were 67% and 63%, respectively. Seven of 11 deceased M‐HLH patients exhibited active malignancy and HLH at the time of death, while only two out of five deceased Ch‐HLH patients had evidence of active HLH. To overcome HLH, malignancy‐ and HLH‐directed treatments were administered in the M‐HLH cohort; however, it was not possible to determine superiority of one approach over the other. For Ch‐HLH, treatment ranged from postponement of chemotherapy to the use of etoposide‐containing regimens.

A recombinant human ADAMTS-13: first-in-human study evaluating pharmacokinetics, safety and tolerability in cTTP patients.

Safety, tolerability, and pharmacokinetics of recombinant ADAMTS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13; BAX 930; SHP655) were investigated in 15 patients diagnosed with severe congenital ADAMTS-13 deficiency (plasma ADAMTS-13 activity <6%) in a prospective phase 1, first-in-human, multicenter dose escalation study. BAX 930 was well tolerated, no serious adverse events occurred, and no anti-ADAMTS-13 antibodies were observed. After single-dose administration of BAX 930 at 5, 20, or 40 U/kg body weight to adolescents and adults, there was approximate dose proportionality with respect to maximum plasma concentration (Cmax [U/mL]) and area under the concentration-time curve (AUC [h∙U/mL]). Dose-related increases of individual ADAMTS-13:Ag and activity were observed and reached a maximum within 1 hour. With escalating BAX 930 doses administered, a dose-dependent persistence of ADAMTS-13-mediated von Willebrand factor (VWF) cleavage products and reduced VWF multimeric size were observed. This study demonstrated that pharmacokinetic parameters of BAX 930 were comparable to those estimated in previous plasma infusion studies and provided evidence of pharmacodynamic activity. This study was registered at www.clinicaltrials.gov as #NCT02216084.

The splenic autoimmune response to ADAMTS13 in thrombotic thrombocytopenic purpura contains recurrent antigen-binding CDR3 motifs

Acquired thrombotic thrombocytopenic purpura (TTP) is the consequence of a severe ADAMTS13 deficiency resulting from autoantibodies inhibiting ADAMTS13 or accelerating its clearance. Despite the success of plasma exchange the risk of relapse is high. From 2 patients (A and B), splenectomized for recurrent episodes of acquired TTP, the splenic B-cell response against ADAMTS13 was characterized through generation of human monoclonal anti-ADAMTS13 autoantibodies (mAbs) by cloning an immunoglobulin G (IgG)4κ- and IgG4λ-Fab library using phage display technology and by Epstein-Barr virus transformation of switched memory B cells (CD19+/CD27+/IgG+). Sequence analysis of the anti-ADAMTS13 IgGs of both patients revealed that the VH gene use was limited in our patients to VH1-3 (55%), VH1-69 (17%), VH3-30 (7%), and VH4-28 (21%) and contained 8 unique and thus far not reported heavy-chain complementarity determining region 3 motifs, of which 4 were shared by the 2 patients. The discovery of several highly similar anti-ADAMTS13 autoantibodies in 2 unrelated TTP patients suggests that the autoimmune response is antigen driven, because the probability that such similar immunoglobulin rearrangements happen by chance is very low (< 10(-9)).

US and MRI of gastrointestinal graft-versus-host disease

Abstract. Abdominal problems often complicate the clinical course after bone marrow transplantation. Graft-versus-host disease occurs as a complication of allogenic bone marrow transplantation. In this report, the findings of intestinal involvement are described and correlated with histopathological findings. Increased bowel-wall thickness and increased vascularity were shown by US. MRI demonstrated generalised increased bowel-wall thickness associated with bowel-wall enhancement after administration of IV gadolinium.

Sequential decisions on FAS sequencing guided by biomarkers in patients with lymphoproliferation and autoimmune cytopenia

Clinical and genetic heterogeneity renders confirmation or exclusion of autoimmune lymphoproliferative syndrome difficult. To re-evaluate and improve the currently suggested diagnostic approach to patients with suspected FAS mutation, the most frequent cause of autoimmune lymphoproliferative syndrome, we prospectively determined 11 biomarkers in 163 patients with splenomegaly or lymphadenopathy and presumed or proven autoimmune cytopenia(s). Among 98 patients sequenced for FAS mutations in CD3+TCRα/β+CD4−CD8− “double negative” T cells, 32 had germline and six had somatic FAS mutations. The best a priori predictor of FAS mutations was the combination of vitamin B12 and soluble FAS ligand (cut-offs 1255 pg/mL and 559 pg/mL, respectively), which had a positive predictive value of 92% and a negative predictive value of 97%. We used these data to develop a web-based probability calculator for FAS mutations using the three most discriminatory biomarkers (vitamin B12, soluble FAS ligand, interleukin-10) of the 11 tested. Since more than 60% of patients with lymphoproliferation and autoimmune cytopenia(s) in our cohort did not harbor FAS mutations, 15% had somatic FAS mutations, and the predictive value of double-negative T-cell values was rather low (positive and negative predictive values of 61% and 77%, respectively), we argue that the previously suggested diagnostic algorithm based on determination of double-negative T cells and germline FAS sequencing, followed by biomarker analysis, is not efficient. We propose vitamin B12 and soluble FAS ligand assessment as the initial diagnostic step with subsequent decision on FAS sequencing supported by a probability-calculating tool.

High-flow priapism in acute lymphatic leukaemia

Priapism is defined as prolonged and persistent erection of the penis without sexual stimulation. It is associated with excessive hyperleukocytosis (e.g. in acute or chronic leukaemia); however, this complication is rarely seen in the pediatric population. We report a 12-year-old boy suffering from acute leukaemia presenting with, at first intermittent, but increasingly persistent erection. Doppler US revealed signs of high-flow priapism. MRI excluded intrapelvic tumour masses, and three-dimensional contrast-enhanced MR angiography could not demonstrate an arteriovenous fistula or thrombosis. Cavernosal blood-gas measurement was in agreement with high-flow priapism. On the basis of the imaging findings, invasive therapeutic management was avoided in our patient with a successful outcome.

Immature platelet fraction as marker for platelet recovery after stem cell transplantation in children.

OBJECTIVES Thrombocytopenia occurs in pediatric patients after SCT and has to be treated with platelet transfusions which bear certain risks and represent a significant cost factor. Monitoring immature platelet (IPF) fraction has been proposed to predict platelet recovery thereby reducing the need for transfusions. DESIGN AND METHODS Hematological parameters including IPF were systematically studied in 17 pediatric patients after either peripheral blood or bone marrow stem cell transplantation. RESULTS Time to platelet recovery depended on the source of stem cells while no differences were detected between percentaged IPF peak concentration and time between IPF peak concentration and platelet recovery between the groups. Correlation between the timepoints of percentaged IPF peak and platelet recovery was high but large interindividual differences were observed concerning the duration of this period. In addition, in some patients high IPF concentrations were not followed by platelet recovery. CONCLUSIONS Although in general high IPF concentrations are followed by platelet recovery wide interindividual variations exist and even no recovery was recorded in four patients. As the latter children are not readily identifiable beforehand IPF should not be used to omit platelet transfusions.