Immunosuppressive therapy is the treatment of choice in children with acquired severe aplastic anemia (AA) and no HLA-matched family donor. The paper presents results of a multicenter study of 63 children with AA treated with rabbit antithymocyte globulin (r-ATG) and cyclosporine A as the first line treatment in the years 1996-2012. Therapeutic effects were evaluated at Days 112, 180, and 360. At Day 112, remission was achieved in 28 out of the 63 patients (44.4 %), complete remission in 10 patients (15.9 %), and partial remission in 18 (28.5 %). At Day 180, 31 patients (49.2 %) were in remission including 15 cases in complete (23.8 %), and 16 cases in partial remission (25.4 %). One year after therapy onset, 34 patients (64.9 %) were in remission including 24 patients (38.0 %) in complete and 10 (15.9 %) in partial remission. Relapse occurred in 4 patients, from 8 months up to 2 years and 2 months after remission. One child, 5 years after remission, was diagnosed with paroxysmal nocturnal hemoglobinuria. The estimated 10-year overall survival rate and 10-year event-free survival rate were 67 % and 57 %, respectively.

Toxocariasis is one of the most common zoonoses, with high seroprevalence in apparently healthy individuals. Neuroblastoma is an aggressive childhood cancer. The cure rates are improving due to dose-dense chemotherapy, progress in surgical practice, myeloablative therapy with autologous stem cell transplantation, and recently, anti-GD2 immunotherapy. This is associated with a burden of complications, some of which are relatively specific for neuroblastoma treatment. Based on previous reports of Toxocara canis infection in high-risk neuroblastoma patients and cases of pulmonary exacerbation from our center in this disease, we propose that toxocariasis is a specific complication of intensive pediatric cancer treatment and advocate for active surveillance.

3435 Objective: One of the main patophysiological mechanism of aplastic anemia (AA) is immune-mediated destruction of hematopoietic cells. In children with severe acquired aplastic anemia (SAA) allogenic bone marrow transplantation is the first choice. If there is no matched sibling donor the first line of treatment is immunosuppressive therapy (IST) which consists of ATG combined with cyclosporine A. Aim. The aim of this study was to analyze the results of IST containing rabbit anti-thymocyte globulin (r-ATG) performed on children with SAA and vSAA treated between 1996–2009 yr. We wanted to assess the influence of such factors as response to treatment, etiology, sex, age, type of AA, for: event free survival (EFS), and progression free survival (PFS) We analyzed deaths rate, relapses rate, clonality and side effects of IST. Materials and methods. We retrospectively analyzed group of 55 children with SAA and vSAA. The group consisted of 23 girls and 32 boys, the median age was 10 years (range 6mth-17,5 years). IST contained antithymocyte globulin,given intravenous at a dose of 3,75 mg/kg/day for 5 days, and cyclosporine A(CSA) at 5 mg/kg/day by mouth in divided doses started on day 1 and continued for at least 6 months(till 24 months). Response rate was assessed on 112, 180 and 360 day and defined as CR, PR, NR. Kaplan–Meier estimator, univariate analysis and multivariate Cox regression models were used to estimate the influence of such factors as response to treatment, etiology, sex, age for EFS, PFS, toxicity and other side effects. Results. The 2- year probability of event free survival (EFS) was 71,52%. The 5 and 10 –year EFS was 57,7%. Progression free survival (PFS) was 66,53%, at 2 years and 59,13% at 5- and 10 year Patients with CR and PR had significantly longer EFS than children with no response(NR) (p<0.0001 Wilcoxon). There was no significant correlation between EFS, PFS and such factors as etiology, sex, age, severity of AA (p > 0,05 Log rank). In all group we observed 15 deaths (27,27%), 5 early and 10 late deaths. Infections were the main causes of death. The relapse rate was 1,81%. The 2-year probability of not having relapse was 87,68%. Relapse free survival was 75,16% at 5 and 10 years. There was one transformation to paroxysmal nocturnal hemoglobinuria (PNH).Non responders (4 patients) received second IST and 11 children underwent MUD-BMT. Infections were the most often side effects of IST (FUO-26,92% of infectious side effects). There was significant association found between EFS and infectious side effects. (p=0,00093 log rank) The most common adverse effects after rabbit immunoglobulin were fever (30,30%) and dyspnoe (24,24%). After CSA treatment we observed mainly gingival hyperplasia (29,16% of side effects of CSA). Most common hemorrhagic side effects were skin petechie. There was significant correlation between hemorrhagic side effects and PFS (p= 0,0144 log rank) Conclusions. 1. Rabbit-ATG is an effective frontline therapy for children with SAA without familiar bone marrow donor.2.Remission achieved on day 112 seems to be constant. 3.5-year EFS seems to be stable within next 5 years.4.5-year relapse free survival seems to be constant during the next 5 years.5.Etiology, type of SAA, age and sex have no influence on the survival.)6.Infectious and hemorrhagic side effects are a very important factors affecting the survival rate in children with SAA. Disclosures: No relevant conflicts of interest to declare.

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4220 Bone marrow transplantation (BMT) is a therapy of choice in children with severe aplastic anemia (SAA), but it is possible only in about 15-20% patients who have family donors, so the majority of them received the immunosuppressive therapy (IST). We want to present the results of IST obtained in 116 children treated between 1993-2008 years at 11 pediatric hematology centers of the Polish Pediatric Hematology Group (PPHG),, 55 patients (22 girls and 33 boys aged 0,6-17,5 years) received antithymocyte rabbit globulin (ATG) as a first course of therapy. ATG was administered according to PPHG and Working Party SAA Group of EBMT protocol: ATG 3.75mg/kg iv for 5 days, cyclosporin A (CSA) 5mg/kg orally from day 1 to day 180 and granulocyte-stimulating factor during deep neutropenia. Remission of the disease was assessed on days 112, 180 and 360 from start of therapy on the basis of blood and bone marrow examination. The results on 112 and 180 were similar. The remission was achieved in 28 of 55 children (51%), complete remission (CR) in 5 children (9%), and partial remission (PR) in 23 children (42%). On day 360 remission was obtained in 30 of 55 patients (42 %), CR in 10 children (18%) and PR in 20 children (36%) There was no response to treatment (NR) in 25 patients (45%). In the group of 55 patients, 15 died (27%). 5 of them died early (day 52 and day 72 of therapy) due to septicemia and central nervous system (CNS) hemorrhage. The other 10 died late (day 99 and day 360 of therapy) due to CNS hemorrhage. Observation time of patients ranged from 1 to 14 years. During this time we noted four relapse. PNH was observed in one patient. The probability of 14 year survival in our group of patients treated initially with rabbit ATG is 72,7%. The results in the last follow up (Jun 2009) are better then earlier. We observed CR in 23/55 children (42%), PR in 10/55 (18%), NR 18/55 (33%). o information about 4 patients. We conclude that initial treatment with rabbit ATG is safe and effective in children. Further studies are needed, to assess long-term effectiveness of rabbit ATG in IST. Disclosures: No relevant conflicts of interest to declare.