Marco Zecca

Mutations in CBL occur frequently in juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia is an aggressive myeloproliferative disorder characterized by malignant transformation in the hematopoietic stem cell compartment with proliferation of differentiated progeny. Seventy-five percent of patients harbor mutations in the NF1, NRAS, KRAS, or PTPN11 genes, which encode components of Ras signaling networks. Using single nucleotide polymorphism arrays, we identified a region of 11q isodisomy that contains the CBL gene in several JMML samples, and subsequently identified CBL mutations in 27 of 159 JMML samples. Thirteen of these mutations alter codon Y371. In this report, we also demonstrate that CBL and RAS/PTPN11 mutations were mutually exclusive in these patients. Moreover, the exclusivity of CBL mutations with respect to other Ras pathway-associated mutations indicates that CBL may have a role in deregulating this key pathway in JMML.

Preemptive Therapy of EBV-Related Lymphoproliferative Disease after Pediatric Haploidentical Stem Cell Transplantation

The treatment of Epstein‐Barr virus (EBV)‐related post‐transplant lymphoproliferative disease (PTLD) after hematopoietic stem cell transplantation (HSCT) is still unsatisfactory. We conducted a prospective trial to evaluate the impact of routine EBV surveillance and preemptive treatment with the anti‐CD20 monoclonal antibody rituximab on the development of PTLD in pediatric recipients of extensively T‐cell depleted HSCT from an HLA‐haploidentical relative. Twenty‐seven patients were included in the surveillance program, 12 developed EBV DNA positivity, with 8 of 12 presenting with sustained viral DNA levels requiring treatment with rituximab. Treatment was well tolerated, and induced clearance of EBV DNA in all patients. However, 4/8 patients showed a new increase in EBV load, coincident with the emergence of CD20−/CD19+ B cells in peripheral blood, accompanied by overt PTLD in 3 patients. The latter cleared PTLD after receiving donor EBV‐specific cytotoxic T‐lymphocytes (CTLs), and persist in remission at a median 30‐month follow‐up. EBV‐specific T‐cell frequency, undetectable at time of EBV DNA positivity, was restored by T‐cell therapy to levels comparable with controls. We conclude that preemptive therapy with rituximab is safe, but only partly effective in haplo‐HSCT recipients. Patients who progress to PTLD under rituximab treatment can be rescued permanently by infusion of EBV‐specific CTLs.

Imatinib for refractory chronic graft-versus-host disease with fibrotic features

We previously reported that patients with fibrotic, chronic graft-versus-host disease (cGVHD) have antibodies activating the platelet-derived growth factor receptor pathway. Because this pathway can be inhibited by imatinib, we performed a pilot study including 19 patients with refractory cGVHD, given imatinib at a starting dose of 100 mg per day. All patients had active cGVHD with measurable involvement of skin or other districts and had previously failed at least 2 treatment lines. Patient median age was 29 years (range, 10-62 years), and median duration of cGvHD was 37 months (range, 4-107 months). The organs involved were skin (n = 17), lung (n = 11), and bowel (n = 5); 15 patients had sicca syndrome. Imatinib-related, grade 3 to 4 toxicity included fluid retention, infections, and anemia. Imatinib was discontinued in 8 patients: in 3 because of toxicity and in 5 because of lack of response (n = 3) or relapse of malignancy (n = 2). Overall response rate at 6 months was 79%, with 7 complete remissions (CRs) and 8 partial remissions (PRs). With a median follow-up of 17 months, 16 patients are alive, 14 still in CR or PR. The 18-month probability of overall survival is 84%. This study suggests that imatinib is a promising treatment for patients with refractory fibrotic cGVHD.

Co-infusion of ex vivo- expanded, parental MSCs prevents life-threatening acute GVHD, but does not reduce the risk of graft failure in pediatric patients undergoing allogeneic umbilical cord blood transplantation

When compared with BMT, umbilical cord blood transplantation (UCBT) is associated with a lower rate of engraftment and delayed hematological/immunological recovery. This leads to increased risk of TRM in the early post transplantation period due to infection. Acute GVHD, although occurring less frequently in UCBT compared with BMT, is also significantly associated with increased rate of early TRM. BM MSCs are known to support normal in vivo hematopoiesis, and co-transplantation of MSCs has been shown to enhance engraftment of human cord blood hematopoietic cells in nonobese diabetic/SCID mice. In 13 children with hematological disorders (median age 2 years) undergoing UCBT, we co-transplanted paternal, HLA-disparate MSCs with the aim of improving hematological recovery and reducing rejection. We observed no differences in hematological recovery or rejection rates compared with 39 matched historical controls, most of whom received G-CSF after UCBT. However, the rate of grade III and IV acute GVHD was significantly decreased in the study cohort when compared with controls (P=0.05), thus resulting in reduced early TRM. Although these data do not support the use of MSCs in UCBT to support hematopoietic engraftment, they suggest that MSCs, possibly because of their immunosuppressive effect, may abrogate life-threatening acute GVHD and reduce early TRM.

Analysis of immune reconstitution in children undergoing cord blood transplantation

OBJECTIVE The aim of this study was to investigate and compare immune reconstitution in allogeneic cord blood transplantation (CBT) and bone marrow transplantation (BMT) recipients. MATERIALS AND METHODS Twenty-three children underwent CBT from either human leukocyte antigen-identical siblings (11 cases) or unrelated donors (12 cases) were enrolled in the study, together with 23 matched children receiving BMT. Patients were analyzed 2-3 and 12-15 months after transplant. Recovery of T-, B-, and NK-lymphocyte subsets, proliferative in vitro response to mitogens, as well as cytotoxic activities, were investigated. RESULTS CBT recipients showed a marked increase in the number of B lymphocytes as compared with patients who underwent BMT (p < 0.001). The absolute number of CD3(+) and CD8(+) T cells, as well as the proliferative response to T-cell mitogens, recovered with time after transplantation, irrespective of the source of stem cells used. Recipients of unrelated CBT had a better recovery of CD4(+) T lymphocytes (p < 0.01). Among patients experiencing acute graft-versus-host disease (GVHD), children given CBT had a much greater production of CD4(+) CD45RA(+) T cells than BMT recipients (p < 0.005). Recovery of NK cell number and innate cytotoxic activities was fast, irrespective of the source of stem cells used. CONCLUSIONS Despite the much lower number of lymphocytes transferred with the graft, recovery of lymphocyte number and function toward normal in CBT recipients was rapid and comparable to that observed after transplantation of bone marrow progenitors. This prompt immune recovery possibly was favored by the reduced incidence and severity of GVHD observed in children who underwent CBT.

Marked and sustained improvement two years after autologous stem cell transplantation in a girl with systemic sclerosis

Autologous transplantation of hematopoietic stem cells has recently been proposed as a possible treatment for autoimmune diseases that are associated with a very severe prognosis. A 12-year-old girl who, since 4 years of age, had systemic sclerosis with progressive pulmonary involvement underwent autologous peripheral blood-derived stem cell transplantation (aPBSCT) using CD34+ selection, cyclophosphamide, and the infusion of the monoclonal antibody CAMPATH-1G. Following transplantation, in the absence of any treatment other than symptomatic therapy, the patients exertional dyspnea and alveolitis disappeared and she experienced a marked improvement in skin score, height velocity, and general well-being that has persisted 2 years after the transplantation procedure. Autologous PBSCT associated with the infusion of the monoclonal antibody CAMPATH-1G appears to be a useful therapy for otherwise intractable forms of progressive systemic sclerosis.

Antibody response to pneumococcal vaccine in children receiving bone marrow transplantation

Fifty-three pediatric patients given an allogeneic or an autologous bone marrow transplantation (BMT) were immunized with a polyvalent pneumococcal capsular polysaccharide vaccine (Pneumovax II). Vaccine was administered six months or more after BMT and the pneumococcal IgM, total IgG, and IgG subclasses levels were evaluated before and three weeks after immunization. Immunization promoted a significant rise in antibody serum levels (P<0.000001), and all children vaccinated more than two years after transplantation responded to pneumococcal polysaccharides, whereas only 20–30% and 50% of patients given BMT between six months and one year and one and two years, respectively, mounted an eifective antibody production (P<0.0001). In univariate analysis, lapse of time from BMT to vaccination, chronic graft-versus-host disease occurrence, and female sex influenced the response rate. However, in multivariate analysis, only time between marrow transplant and immunization was a powerful predictor of response. Interestingly, four of 11 patients with IgG2 deficiency before immunization normalized serum levels of this IgG subclass after the pneumococcal antigenic challenge. Our study suggests that time after transplant is the major factor influencing the recovery of immune reactivity to polysaccharide antigens. This seems to confirm the hypothesis that ontogeny of the B-cell repertoire follows a predetermined sequential program in which polysaccharide antigens are some of the last to evoke an antibody response.

Cyclosporin A response and dependence in children with acquired aplastic anaemia: a multicentre retrospective study with long-term observation follow-up.

Immunosuppressive therapy (IST) with antithymocyte globulin and cyclosporin A (CyA) is the standard treatment for children with acquired aplastic anaemia (AAA) lacking a matched donor. Survival rates of more than 80% at 5 years are achieved, but the response is drug‐dependent in 15–25% of cases. This study, of 42 consecutive children with AAA treated with IST, assessed the incidence of CyA‐dependence, CyA and granulocyte colony‐stimulating factor (G‐CSF) tapering schedules and the impact of drug accumulation on progression to myelodysplasia/acute myeloid leukaemia (MDS/AML). Overall survival was 83% at 10 years. CyA‐dependence without a predictive marker was observed in 18% of responders. Probability of discontinuing CyA was 60·5% at 10 years; a slow CyA tapering schedule was performed in 84% of patients; the cumulative incidence of relapse was 16% at 10 years. Relapse risk was significantly associated with rapid CyA discontinuation: 60% compared to 7·6% in the slow tapering group (P = 0·001). Cumulative incidence of MDS/AML was 8% at 10 years, with a significant correlation with both G‐CSF cumulative dose and second IST. This long‐term follow‐up of children with AAA shows that IST with a slow CyA tapering course is an effective treatment with a low‐relapse rate in these cases.

Complex karyotype newly defined: the strongest prognostic factor in advanced childhood myelodysplastic syndrome

To identify cytogenetic risk factors predicting outcome in children with advanced myelodysplastic syndrome, overall survival of 192 children prospectively enrolled in European Working Group of Myelodysplastic Syndrome in Childhood studies was evaluated with regard to karyotypic complexity. Structurally complex constitutes a new definition of complex karyotype characterized by more than or equal to 3 chromosomal aberrations, including at least one structural aberration. Five-year overall survival in patients with more than or equal to 3 clonal aberrations, which were not structurally complex, did not differ from that observed in patients with normal karyotype. Cox regression analysis revealed the presence of a monosomal and structurally complex karyotype to be strongly associated with poor prognosis (hazard ratio = 4.6, P < .01). Notably, a structurally complex karyotype without a monosomy was associated with a very short 2-year overall survival probability of only 14% (hazard ratio = 14.5; P < .01). The presence of a structurally complex karyotype was the strongest independent prognostic marker predicting poor outcome in children with advanced myelodysplastic syndrome.

Incidence and treatment of hemorrhagic cystitis in children given hematopoietic stem cell transplantation: a survey from the Italian association of pediatric hematology oncology–bone marrow transplantation group

Summary:The purpose of this multicenter study was to assess the incidence and the treatment of hemorrhagic cystitis (HC) in 1218 pediatric patients, with a mean age of 10.8 years, who underwent hematopoietic stem cell transplantation (HSCT). In all, 44 patients (3.6%) developed HC a median 23 days after HSCT. The incidence of HC was higher in allogeneic than in autologous HSCT recipients (P=0.0001). Of the 44 patients, 37 (84%) recovered from HC in a median 30 days (range 3–100); the other seven children died while still suffering from HC. Hyperbaric oxygen therapy (HOT) achieved significantly better results than prostaglandin therapy (P=0.02) in the treatment of grade II–III HC. By multivariate analysis, age <96 months and allogeneic HSCT were significantly associated with the occurrence of HC: P=0.008 and 0.013, respectively. After a median follow-up of 5.75 years, the 5-year survival of patients who did or did not develop HC was: 43 vs 52%, P=0.03, respectively. This study indicates that age and type of HSCT are factors predisposing to HC in children given HSCT and demonstrates the promising role of HOT in a conservative approach to HC treatment.