Marek Ussowicz

Prevalence, clinical characteristics, and prognosis of GATA2-related myelodysplastic syndromes in children and adolescents

Germline GATA2 mutations cause cellular deficiencies with high propensity for myeloid disease. We investigated 426 children and adolescents with primary myelodysplastic syndrome (MDS) and 82 cases with secondary MDS enrolled in 2 consecutive prospective studies of the European Working Group of MDS in Childhood (EWOG-MDS) conducted in Germany over a period of 15 years. Germline GATA2 mutations accounted for 15% of advanced and 7% of all primary MDS cases, but were absent in children with MDS secondary to therapy or acquired aplastic anemia. Mutation carriers were older at diagnosis and more likely to present with monosomy 7 and advanced disease compared with wild-type cases. For stratified analysis according to karyotype, 108 additional primary MDS patients registered with EWOG-MDS were studied. Overall, we identified 57 MDS patients with germline GATA2 mutations. GATA2 mutations were highly prevalent among patients with monosomy 7 (37%, all ages) reaching its peak in adolescence (72% of adolescents with monosomy 7). Unexpectedly, monocytosis was more frequent in GATA2-mutated patients. However, when adjusted for the selection bias from monosomy 7, mutational status had no effect on the hematologic phenotype. Finally, overall survival and outcome of hematopoietic stem cell transplantation (HSCT) were not influenced by mutational status. This study identifies GATA2 mutations as the most common germline defect predisposing to pediatric MDS with a very high prevalence in adolescents with monosomy 7. GATA2 mutations do not confer poor prognosis in childhood MDS. However, the high risk for progression to advanced disease must guide decision-making toward timely HSCT.

Immune reconstitution after haematopoietic cell transplantation in children: immunophenotype analysis with regard to factors affecting the speed of recovery.

Summary.  Immune reconstitution was studied prospectively in 66 children who underwent 77 haematopoietic cell transplantations (HCT): 46 autologous HCTs in 39 patients and 31 allogeneic HCTs in 27 patients. We studied the dynamic analysis of immune recovery with regard to potential factors affecting its speed, including age, type of HCT, diagnosis, graft‐versus‐host disease (GvHD) and cytomegalovirus (CMV) infection reactivation. Absolute counts of different lymphocyte subsets and immunoglobulin serum levels were determined in peripheral blood of patients on d −7 and +16, and then at various intervals up to 24 months post transplant. Common patterns of immune recovery after both allogeneic and autologous HCT were identified: (i) CD4+CD45RO+ peripheral T‐cell expansion on d +16; (ii) inverted CD4+:CD8+ ratio from d +30 onwards; (iii) rapid natural killer (NK) cell (CD16±CD56+) count normalization. We observed prolonged T‐cell lymphopenia (CD3+, CD3+CD4+, CD4+CD45RA+) until 24 months after autologous HCT, whereas in the allogeneic setting CD3+CD4+ cells, including naive CD45RA+ cells, returned to normal values at 9 months post transplant. Age > 10 years and coexistence of GvHD and CMV reactivation were associated with a substantial delay in T‐ (CD4+, including CD45RA+) and B‐cell recovery after allogeneic HCT. Multidrug GvHD prophylaxis resulted in impaired T‐ (CD4+, CD4+CD45RA+) and B‐cell reconstitution only in the early phase after allogeneic HCT (up to 4 months). Our results demonstrated that T‐cell recovery was severely impaired in children after autologous HCT. It should be emphasized that specific approaches to enhance immune reconstitution are necessary to control minimal residual disease and avoid the risk of infectious complications in the autologous setting. Thymic involution after allogeneic HCT seems to be associated with age and coexistence of GvHD and CMV reactivation.

Hematuria Due to Adenoviral Infection in Bone Marrow Transplant Recipients

Late-onset hemorrhagic cystitis (HC) caused by adenovirus (AdV) infection is a common complication in hematopoietic stem cell transplantation (HSCT) recipients. However, limited information exists regarding adenovirus-associated HC. We report a retrospective study of 84 hematopoietic stem cell transplant recipients that evaluated the incidence and risk factors for AdV-induced HC. The development of HC was strongly related to adenoviral infection (P = .004). Among 13 patients who developed late-onset HC, AdVs were identified as a causative agent in 10 cases. AdV preferentially affected younger (P = .013) and male patients. Affected subjects had been transplanted for either malignant (7/10) or nonmalignant disorders (3/10). Most cases of AdV-hematuria were self-limited single or recurrent mild hemorrhagic episodes (P = .000), occurring at a median of 41 days after transplantation and lasting an average of 4 days. Viral load in patients with AdV-induced HC was similar to infected subjects who did not develop HC (2.5 × 10(3) vs 3.4 × 10(3) copies/mL). We HC occurring before 200 days was associated with a greater risk of a fatal outcome (P = .002) but occurrence of AdV infection did not affect a patients survival. Our study confirmed the suggestion that non-AdV coinfections may worsen the course of AdV-HC.

PCR diagnostics and monitoring of adenoviral infections in hematopoietic stem cell transplantation recipients.

After stem cell transplantation, human patients are prone to life-threatening opportunistic infections with a plethora of microorganisms. We report a retrospective study on 116 patients (98 children, 18 adults) who were transplanted in a pediatric bone marrow transplantation unit. Blood, urine and stool samples were collected and monitored for adenovirus (AdV) DNA using polymerase chain reaction (PCR) and real-time PCR (RT-PCR) on a regular basis. AdV DNA was detected in 52 (44.8%) patients, with mortality reaching 19% in this subgroup. Variables associated with adenovirus infection were transplantations from matched unrelated donors and older age of the recipient. An increased seasonal occurrence of adenoviral infections was observed in autumn and winter. Analysis of immune reconstitution showed a higher incidence of AdV infections during periods of low T-lymphocyte count. This study also showed a strong interaction between co-infections of AdV and BK polyomavirus in patients undergoing hematopoietic stem cell transplantations.

Treosulfan-based conditioning regimen in a second matched unrelated peripheral blood stem cell transplantation for a pediatric patient with CGD and invasive aspergillosis, who experienced initial graft failure after RIC.

Chronic granulomatous disease (CGD) is a rare primary immunodeficiency caused by a defect of phagocyte NADPH-oxidase and characterized by severe, recurrent bacterial and fungal infections. Invasive aspergillosis (IA) is the leading cause of mortality in patients with CGD. We report the case of a 3-year-old boy with CGD, who developed IA despite antifungal prophylaxis. His treatment consisted of a 10-month-long multi-drug antifungal therapy, together with surgery, but these did not cause any substantial clinical improvement. BMT in high-risk patients with CGD remains a challenge due to both, higher risk of graft rejection and inflammatory flare in the course of immune recovery. Our patient rejected the first matched unrelated donor (MUD) allograft after RIC regimen recommended by the EBMT Inborn Errors Working Party for high-risk patients. After treosulfan-based conditioning and second MUD peripheral blood stem cell transplantation both, full reconstitution of the granulocytic series and complete recovery from IA, were achieved.

Immunologic Effects of Intermediate-Dose IL-2 i.v. After Autologous Hematopoietic Cell Transplantation in Pediatric Solid Tumors

Adoptive immunotherapy with interleukin-2 (IL-2) may control minimal residual disease (MRD) and prevent relapse after autologous hematopoietic cell transplantation (AHCT). The objective of this study was to determine the immunologic effects of intermediate doses of intravenous (i.v.) IL-2 after AHCT in children with poor-prognosis solid tumors. Eleven patients received a median five cycles consisting of escalating doses of IL-2 i.v. for 5 days after a median time interval of 94 days post-AHCT. The phenotype of lymphocyte subsets was investigated before and after each cycle, and parallel determination of natural killer (NK) cell activity was performed. Immunotherapy induced a significant increase in total lymphocyte count (TLC), T, NK, and, to some extent, B cells. Among NK cells, CD56+ bright cells expanded more than CD56+ dim cells. High expansion of CD56+ cells with CD94 inhibitory receptor was observed, whereas no difference was recorded in the number of CD3+ CD56+ and CD8+ CD57+ cells. NK activity stabilized after the first cycle of IL-2 and remained elevated during the study period. Cycles of IL-2 immunotherapy induced repeated significant expansion of T cells and NK cells, mostly of the immature CD56+ bright phenotype. Despite enhanced NK activity, relapses occurred frequently, which might have been due to increased CD94 activation and a poor response from the cytotoxic NK T cells and CD8+ CD57+ T cells.

Steroid-Sparing Effect of Extracorporeal Photopheresis in the Therapy of Graft-Versus-Host Disease After Allogeneic Hematopoietic Stem Cell Transplantation

INTRODUCTION Steroid-refractory graft-versus-host disease (GVHD) remains a challenging therapeutic problem after allogeneic hematopoietic stem cell transplantation (HSCT). The aim of this study was to evaluate the clinical effect of extracorporeal photopheresis (ECP), and its impact on intensivity of immunosuppresive therapy in allogeneic HSCT patients. PATIENTS AND METHODS In this study 443 Therakos ECP procedures were performed in 21 patients after allogeneic HSCT with acute (aGVHD, 8 patients) or chronic (cGVHD, 13 patients) therapy-refractory GVHD. The median age at ECP onset was 20.5 years (range, 10-55). Venous access was provided by a nontunelized central venous catheter (12 patients) or 9.6-French portacath (9 patients). RESULTS In the cGVHD group 9/13 patients were improved with a 4-year overall survival rate of 67.7%. ECP led to steroid discontinuation in 6 and substantial dose reduction in 5 patients. The prednisone dose equivalent per kilogram body weight decreased from 0.32 mg to 0.07 mg after therapy. Therapy of aGVHD led to complete or partial symptom remission in 3/9 subjects. The change in steroid dose in the aGVHD group was not significant, there were no long-term survivors. Portacath access was well tolerated and provided adequate blood flow rates. CONCLUSIONS The ECP therapy significantly reduced the rates of remissions with steroid discontinuation among cGVHD but not aGVHD patients. Rare ECP-related complications were either catheter related or anticoagulation induced during ECP procedures. Photopheresis was a safe, effective method to treat steroid-resistant cGVHD.

The genetic tumor background is an important determinant for heterogeneous MYCN‐amplified neuroblastoma

Amplification of MYCN is the signature genetic aberration of 20–25% of neuroblastoma and a stratifying marker associated with aggressive tumor behavior. The detection of heterogeneous MYCN amplification (hetMNA) poses a diagnostic dilemma due to the uncertainty of its relevance to tumor behavior. Here, we aimed to shed light on the genomic background which permits hetMNA in neuroblastoma and tied the occurrence to other stratifying markers and disease outcome. We performed SNP analysis using Affymetrix Cytoscan HD arrays on 63 samples including constitutional DNA, tumor, bone marrow and relapse samples of 26 patients with confirmed hetMNA by MYCN‐FISH. Tumors of patients ≤18m were mostly aneuploid with numeric chromosomal aberrations (NCAs), presented a prominent MNA subclone and carried none or a few segmental chromosomal aberrations (SCAs). In older patients, tumors were mostly di‐ or tetraploid, contained a lower number of MNA cells and displayed a multitude of SCAs including concomitant 11q deletions. These patients often suffered disease progression, tumor dissemination and relapse. Restricted to aneuploid tumors, we detected chromosomes with uniparental di‐ or trisomy (UPD/UPT) in almost every sample. UPD11 was exclusive to tumors of younger patients whereas older patients featured UPD14. In this study, the MNA subclone appears to be constraint by the tumor environment and thus less relevant for tumor behavior in aggressive tumors with a high genomic instability and many segmental aberrations. A more benign tumor background and lower tumor stage may favor an outgrowth of the MNA clone but tumors generally responded better to treatment.

Significant changes in the composition of the precursor B‐cell compartment in children less than 2 years old

Background: Defects in early B lymphocyte maturation in bone marrow (BM) compose a characteristic feature of many primary immune deficiencies associated with agammaglobulinemia. To date, only limited data on the composition of the precursor B‐cell compartment in BM is available. The aim of this study was to define normal age‐related ranges of total B‐cell content and distribution of precursor B—cell stages in BM for the future use in clinical diagnostics.

A three-way translocation of MLL, MLLT11, and the novel reciprocal partner gene MYO18A in a child with acute myeloid leukemia.

Translocations of the MLL gene are common among neonates and infants with acute lymphoblastic and acute myeloid leukemias. We characterized a new three-way translocation involving MLL in an infant with acute myeloid leukemia who subsequently relapsed and underwent a hematopoietic stem cell transplant from an unrelated stem cell donor. The translocation was characterized using karyotyping and fluorescence in situ hybridization. In this patient, a complex rearrangement fused the distal part of 11q23 with 17q11.2, the distal part of 17q11.2 with 1q21, and the distal part of 1q21 with 11q23, resulting in a three-way translocation; t(1;11;17)(q21;q23;q11.2). The two reciprocal MLL fusion sites were cloned by long-distance inverse polymerase chain reaction, which led to the identification of MLL-MLLT11 and the reciprocal MYO18A-MLL fusion alleles. Both fusion genes are in-frame and can be translated into functional fusion proteins. Although the MLL-MLLT11 fusion gene has been described in the literature, the reciprocal MYO18A fusion partner is a novel candidate gene in the growing list of reciprocal MLL fusions.