Search

Subclinical cardiotoxicity at low total cumulative doxorubicin (DOX) doses can manifest into cardiomyopathy in long-term cancer survivors. However, the underlying mechanisms are poorly understood. In male B6C3F1 mice, assessment of cardiac function by echocardiography was performed at 1, 4, 10, 17, and 24 weeks after exposure to 6, 9, 12, and 24 mg/kg total cumulative DOX doses or saline (SAL) to monitor development of delayed-onset cardiotoxicity. The 6- or 9-mg/kg total cumulative doses resulted in a significant time-dependent decline in systolic function (left ventricular ejection fraction (LVEF) and fractional shortening (FS)) during the 24-week recovery although there was not a significant alteration in % LVEF or % FS at any specific time point during the recovery. A significant decline in systolic function was elicited by the cardiotoxic cumulative DOX dose (24 mg/kg) during the 4- to 24-week period after treatment compared to SAL-treated counterparts. At 24 weeks after DOX treatment, a significant dose-related decrease in the expression of genes and proteins involved in sarcoplasmic reticulum (SR) calcium homeostasis (Ryr2 and Serca2) was associated with a dose-related increase in the transcript level of Casp12 (SR-specific apoptosis) in hearts. These mice also showed enhanced apoptotic activity in hearts indicated by a significant dose-related elevation in the number of apoptotic cardiomyocytes compared to SAL-treated counterparts. These findings collectively suggest that a steady decline in SR calcium handling and apoptosis might be involved in the development of subclinical cardiotoxicity that can evolve into irreversible cardiomyopathy later in life.

Increasing availability of genomic testing poses new challenges to clinicians, particularly where variant interpretation from commercial sources may be equivocal. The authors report a patient with recurrent rhabdomyosarcoma and subsequent bilateral breast cancer who was found to harbor a previously undescribed germline TP53 sequence alteration annotated by the commercial laboratory as a variant of uncertain significance. By investigating publicly available databases of aggregated normal germline and malignant somatic genomic sequences, the authors conclude that this missense variant, c.476C>T (p.A159V), is a novel, pathogenic Li-Fraumeni syndrome mutation and demonstrate the utility of these resources in clinical pediatric hematology and oncology practice.

Introduction: Hemophilia A is a rare bleeding disorder caused by pathogenic variants in the F8 gene, resulting in insufficient factor VIII (FVIII) activity. Adeno-associated virus (AAV)-mediated gene transfer enables the delivery of a modified functional F8 gene to hepatocytes that subsequently synthesize FVIII at levels that may prevent bleeding events in the absence of exogenous FVIII. Updated results and follow-up from the Alta study, an ongoing gene therapy study in patients with severe hemophilia A, are presented. Methods: The Alta study is a phase 1/2 dose-ranging, single-dose study of giroctocogene fitelparvovec (also known as SB-525 and PF-07055480), a recombinant AAV serotype 6 (rAAV6) vector encoding a modified F8 gene. Adults aged ≥18 years with severe hemophilia A were eligible for inclusion. Giroctocogene fitelparvovec was infused into patients in 4 cohorts of 2 patients each across 4 ascending doses (9e11, 2e12, 1e13, and 3e13 vg/kg). The 3e13 vg/kg dose cohort was expanded with 3 additional patients. Key end points included safety, circulating FVIII activity, use of FVIII replacement therapy, and frequency of bleeding events. Presented data are from the ongoing Alta study (NCT#03061201; data cutoff date, 26 May 2020; database not locked; data reflect those at time of data cutoff, have not undergone standard quality checks, and may be subject to change). Results: Eleven male patients participated in the study (mean [SD] age, 30.3 [7.8] years; white, 81.8%). As of the cutoff date, patients have been followed for 35 to 144 weeks; one patient in the 1e13 vg/kg cohort discontinued from the study. Overall, the most commonly reported adverse events (AEs; n) included increased alanine aminotransferase (ALT; 8 [72.7%]), increased aspartate aminotransferase (AST; 5 [45.5%]), upper respiratory tract infection (4 [36.4%]), and pyrexia (4 [36.4%]). Treatment-related serious AEs were reported in 1 patient (in the 3e13 vg/kg cohort) who experienced hypotension and fever ≈6 hours after giroctocogene fitelparvovec infusion; the events fully resolved with treatment and did not delay post-infusion discharge. In the 3 lower-dose cohorts, no ALT elevation requiring more than 7 days of corticosteroid treatment was observed. Of the 5 patients in the 3e13 vg/kg cohort, 4 had elevations in ALT that were managed with a tapering course of corticosteroids (ranging from 10-134 days) without loss of clinically relevant FVIII activity through 40 weeks, as evidenced by a lack of bleeding events before and after treatment with corticosteroids. Increases in FVIII activity from baseline were generally dose-dependent. Patients in the 3e13 vg/kg cohort achieved a mean normal-range of FVIII activity within 5 weeks post-infusion, with mean FVIII activity maintained through week 40, which is the last time point with data for all 5 patients in this cohort (Table). Following the initial prophylactic period of up to ≈3 weeks after giroctocogene fitelparvovec administration, no bleeding events occurred in any patient treated in the 3e13 vg/kg cohort. Use of FVIII replacement therapy ≥3 weeks after giroctocogene fitelparvovec administration was reported in 5/6 patients in the lower-dose cohorts (range: 9-115 infusions); none of the patients in the 3e13 vg/kg cohort required FVIII replacement beyond initial use of prophylactic factor for up to ≈3 weeks (prophylactic coverage stopped 3 weeks and 2 days after giroctocogene fitelparvovec administration in 1 patient in the 3e13 vg/kg cohort). Conclusions: To date, a single infusion of giroctocogene fitelparvovec gene therapy in patients with severe hemophilia A resulted in dose-dependent and sustained increases in FVIII levels without administration of exogenous FVIII, bleeding episodes or sustained adverse events in the highest-dose cohort (3e13 vg/kg). Additionally, patients treated in the highest-dose cohort achieved a mean FVIII activity in the normal range within 5 weeks, which was maintained through week 40. Data on all patients with more than 1 year of follow-up will also be presented. The study is ongoing, and these interim results support further development of giroctocogene fitelparvovec for the treatment of patients with severe hemophilia A. Disclosures Leavitt: BioMarin: Membership on an entity's Board of Directors or advisory committees. Konkle:Sanofi: Consultancy, Research Funding; Takeda: Research Funding; Uniquire: Research Funding; CSL Behring: Consultancy; BioMarin: Consultancy; Baxalta: Research Funding; Spark: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Sigilon: Consultancy, Research Funding; Roche: Consultancy. Stine:Biomarin: Consultancy; Applied Stem Cell Therapeutics: Consultancy. Visweshwar:Biogen Idec: Membership on an entity's Board of Directors or advisory committees. Giermasz:uniQure: Consultancy, Research Funding; Sangamo Therapeutics: Research Funding; Bioverativ/Sanofi: Consultancy, Research Funding, Speakers Bureau; BioMarin: Consultancy, Research Funding, Speakers Bureau; Genentech/Roche: Consultancy, Research Funding, Speakers Bureau. Arkin:Pfizer: Current Employment, Current equity holder in publicly-traded company, Other: own stock/options in the company. Fang:Pfizer Inc.: Current Employment, Other: own stock/options in the company. Plonski:Pfizer Inc.: Current Employment, Other: own stock/options in the company. Smith:Pfizer Inc.: Current Employment, Other: own stock/options in the company. Tseng:Pfizer Inc.: Current Employment, Other: own stock/options in the company. Di Russo:Pfizer Inc.: Current Employment, Other: own stock/options in the company. Cockroft:Sangamo Therapeutics: Current Employment, Other: Shareholder of Sangamo Therapeutics. Rupon:Pfizer Inc.: Current Employment, Other: own stock/options in the company. Rouy:Sangamo Therapeutics: Current Employment, Other: Shareholder of Sangamo Therapeutics.

Background Data on second-line treatment options for pediatric patients with immune thrombocytopenia (ITP) are limited. Thrombopoietin receptor agonists (TPO-RA) provide a nonimmunosuppressive option for children who require an increased platelet count. Procedure We performed a multicenter retrospective study of pediatric ITP patients followed at ITP Consortium of North America (ICON) sites to characterize TPO-RA use. Results Seventy-nine children had a total of 87 treatments (28 eltrombopag, 43 romiplostim, and eight trialed on both). The majority had primary ITP (82%) and most (60.8%) had chronic ITP. However, 22% had persistent ITP and 18% had newly diagnosed ITP. During the first 3 months of treatment, 89% achieved a platelet count ≥ 50 × 109/l (86% romiplostim, 81% eltrombopag, P = 0.26) at least once in the absence of rescue therapy. The average time to a response was 6.4 weeks for romiplostim and 7.0 weeks for eltrombopag (P = 0.83). Only 40% of patients demonstrated a stable response with consistent dosing over time. An intermittent response with constant dose titration was seen in 15%, and an initial response that waned to no response was seen in 13%. Significant adverse events were minimal with the exception of two patients with thrombotic events and one who developed a neutralizing antibody. Conclusions Our results demonstrate that TPO-RA agents are being used in children with ITP of varying duration and severity. The response was similar to clinical trials, but the sustainability of response varied. Future studies need to focus on the ideal timing and rationale for these medications in pediatric patients.

The majority of Osteosarcoma (OS) patients are treated with a combination of chemotherapy, resection, and limb salvage protocols. These protocols include distraction osteogenesis (DO), which is characterized by direct new bone formation. Cisplatin (CDP) is extensively used for OS chemotherapy and recent studies, using a mouse DO model, have demonstrated that CDP has profound negative effects on bone repair. Recent oncological therapeutic strategies are based on the use of standard cytotoxic drugs plus an assortment of biologic agents. Here we demonstrate that the previously reported CDP-associated inhibition of bone repair can be modulated by the administration of a small molecule p53 inducer (nutlin-3). The effects of nutlin-3 on CDP osteotoxicity were studied using both pre- and post-operative treatment models. In both cases the addition of nutlin-3, bracketing CDP exposure, demonstrated robust and significant bone sparing activity (p < 0.01-0.001). In addition the combination of nutlin-3 and CDP induced equivalent OS tumor killing in a xenograft model. Collectively, these results demonstrate that the induction of p53 peri-operatively protects bone healing from the toxic effects of CDP, while maintaining OS toxicity. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1716-1724, 2016.

Introduction: Hemophilia A is a rare blood disorder caused by an F8 variant resulting in insufficient Factor VIII (FVIII) activity. Updated results and follow-up of an ongoing gene therapy study in patients with severe hemophilia A are presented. Methods: The Alta study is a dose-ranging, single-dose study of SB-525 gene therapy, a recombinant adeno-associated virus (rAAV6) vector encoding an F8 gene. SB-525 was injected into 11 patients in 4 cohorts of 2 patients each across 4 ascending doses (9e11, 2e12, 1e13 and 3e13 vg/kg) with expansion of the high dose cohort by 3 additional patients. Endpoints included: safety events, changes in circulating FVIII activity, FVIII antigen, FVIII usage, and frequency and severity of bleeding. Results: In the third cohort (1e13 vg/kg), a single infusion of SB-525 resulted in stable and clinically relevant increases in FVIII activity. Patients in the fourth cohort (high dose, 3e13 vg/kg) achieved FVIII levels within the normal range (Table 1), with no bleeding events reported up to 24 weeks post-injection. Patients treated at 3e13 vg/kg did not require FVIII replacement therapy following the initial prophylactic period of up to approximately 3 weeks post-SB-525 administration. No bleeding events were observed in any of the patients treated at the 3e13 vg/kg dose. One patient had a treatment-related serious adverse event of hypotension and fever, with symptoms of headache and tachycardia, which occurred ~6 hours after completion of the vector infusion and resolved with treatment within 24 hours. In the three first cohorts, no ALT elevation requiring more than 7 days of corticosteroid treatment was observed. Of the 5 patients treated to date in the high dose cohort, 3 followed for at least 8 weeks showed transient and mild (grade 1) ALT elevations. All responded to corticosteroids within one week. At the time of abstract submission, all patients were off corticosteroids. FVIII antigen was assessed by ELISA, and preliminary results from the high dose cohort showed a good correlation by chromogenic assay between the specific activity of SB-525 derived FVIII and Xyntha, a recombinant B-domain deleted protein control. Dosing in the fourth cohort is ongoing, and additional analyses of the trial data including FVIII levels, bleeding rate and factor usage will be presented as available. Four- to 11-month follow-up data on all patients in the fourth dose cohort will also be presented. Conclusions: To date, treatment with a single infusion of SB-525 gene therapy resulted in dose-dependent and sustained increases in FVIII levels, with a substantial decrease in FVIII usage, and no bleeding episodes recorded in the highest dose cohort. Patients treated in the highest dose cohort achieved FVIII activity in the normal range. No ALT elevations persisting longer than 7 days were observed in the first three dose cohorts. The study is ongoing, and the results support further development of SB-525 for the treatment of severe Hemophilia A. Disclosures Giermasz: uniQure: Consultancy, Other: Research; Sangamo: Other: Research; Bioverativ/Sanofi: Consultancy, Speakers Bureau; BioMarin: Consultancy, Other: Research; Genentech/Roche: Consultancy, Other: Research, Speakers Bureau. Arkin:Pfizer: Employment, Equity Ownership. Di Russo:Pfizer: Employment, Equity Ownership. Snyder:Sangamo Therapeutics: Employment. Woolfson:Sangamo Therapeutics: Employment, Equity Ownership. Rouy:Sangamo Therapeutics: Employment, Equity Ownership.

Juvenile myelomonocytic leukemia (JMML) is a myeloproliferative neoplasm (MPN) of childhood with a poor prognosis. Mutations in NF1, NRAS, KRAS, PTPN11 and CBL occur in 85% of patients, yet there are currently no risk stratification algorithms capable of predicting which patients will be refractory to conventional treatment and therefore be candidates for experimental therapies. In addition, there have been few other molecular pathways identified aside from the Ras/MAPK pathway to serve as the basis for such novel therapeutic strategies. We therefore sought to genomically characterize serial samples from patients at diagnosis through relapse and transformation to acute myeloid leukemia in order to expand our knowledge of the mutational spectrum in JMML. We identified recurrent mutations in genes involved in signal transduction, gene splicing, the polycomb repressive complex 2 (PRC2) and transcription. Importantly, the number of somatic alterations present at diagnosis appears to be the major determinant of outcome.

Objective.To seek insights into the heterogeneity of macrophage activation syndrome (MAS) complicating systemic juvenile idiopathic arthritis (sJIA) through the analysis of a large patient sample collected in a multinational survey.Methods.International pediatric rheumatologists and hemato-oncologists entered their patient data, collected retrospectively, in a Web-based database. The demographic, clinical, laboratory, histopathologic, therapeutic, and outcome data were analyzed in relation to (1) geographic location of caring hospital, (2) subspecialty of attending physician, (3) demonstration of hemophagocytosis, and (4) severity of clinical course.Results.A total of 362 patients were included by 95 investigators from 33 countries. Demographic, clinical, laboratory, and histopathologic features were comparable among patients seen in diverse geographic areas or by different pediatric specialists. Patients seen in North America were given biologics more frequently. Patients entered by pediatric hemato-oncologists were treated more commonly with biologics and etoposide, whereas patients seen by pediatric rheumatologists more frequently received cyclosporine. Patients with demonstration of hemophagocytosis had shorter duration of sJIA at MAS onset, higher prevalence of hepatosplenomegaly, lower levels of platelets and fibrinogen, and were more frequently administered cyclosporine, intravenous immunoglobulin (IVIG), and etoposide. Patients with severe course were older, had longer duration of sJIA at MAS onset, had more full-blown clinical picture, and were more commonly given cyclosporine, IVIG, and etoposide.Conclusion.The clinical spectrum of MAS is comparable across patients seen in different geographic settings or by diverse pediatric subspecialists. There was a disparity in the therapeutic choices among physicians that underscores the need to establish uniform therapeutic protocols.

OBJECTIVE: To develop and validate a diagnostic score that assists in discriminating primary hemophagocytic lymphohistiocytosis (pHLH) from macrophage activation syndrome (MAS) related to systemic juvenile idiopathic arthritis. STUDY DESIGN: The clinical, laboratory, and histopathologic features of 362 patients with MAS and 258 patients with pHLH were collected in a multinational collaborative study. Eighty percent of the population was assessed to develop the score and the remaining 20% constituted the validation sample. Variables that entered the best fitted model of logistic regression were assigned a score, based on their statistical weight. The MAS/HLH (MH) score was made up with the individual scores of selected variables. The cutoff in the MH score that discriminated pHLH from MAS best was calculated by means of receiver operating characteristic curve analysis. Score performance was examined in both developmental and validation samples. RESULTS: Six variables composed the MH score: age at onset, neutrophil count, fibrinogen, splenomegaly, platelet count, and hemoglobin. The MH score ranged from 0 to 123, and its median value was 97 (1st-3rd quartile 75-123) and 12 (1st-3rd quartile 11-34) in pHLH and MAS, respectively. The probability of a diagnosis of pHLH ranged from 99% for a score of =123. A cutoff value of =60 revealed the best performance in discriminating pHLH from MAS. CONCLUSION: The MH score is a powerful tool that may aid practitioners to identify patients who are more likely to have pHLH and, thus, could be prioritized for functional and genetic testing.

Background Treatment of chronic severe pediatric ITP is not well studied. In a phase 1/2 12–16-week study, 15/17 romiplostim-treated patients achieved platelet counts ≥50 × 109/L, and romiplostim treatment was well tolerated. In a subsequent open-label extension (≤109 weeks), 20/22 patients received romiplostim; all achieved platelet counts >50 × 109/L. Twelve patients continued in a second extension (≤127 weeks). Longitudinal data from start of romiplostim treatment through the two extensions were evaluated to investigate the safety and efficacy of long-term romiplostim treatment in chronic severe pediatric ITP. Procedure Patients received weekly subcutaneous romiplostim, adjusted by 1 µg/kg/week to maintain platelet counts (50–200 × 109/L, maximum dose 10 µg/kg). Bone marrow examinations were not required. Results At baseline, patients were median age 10.0 years; median ITP duration 2.4 years; median platelet count 13 × 109/L; 73% were male; and 36% had prior splenectomy. Median romiplostim treatment duration was 167 weeks (Q1, Q3: 78,227 weeks), and median average weekly dose was 5.4 µg/kg (Q1, Q3: 4.3, 8.0 µg/kg). Seven patients discontinued treatment: four withdrew consent, two were noncompliant, and one received alternative therapy. None withdrew because of adverse events (AEs). After the first 12 weeks, median platelet counts remained >50 × 109/L. Eight (36.4%) patients received rescue medication, and 14 (63.6%) used concurrent ITP therapy. Seven patients (31.8%) reported serious AEs, and two (9.1%) reported life-threatening AEs (both thrombocytopenia); there were no serious AEs attributed to treatment and no fatalities. Conclusions Long-term romiplostim treatment in this small cohort increased and maintained platelet counts for over 4 years in children with ITP with good tolerability and without significant toxicity. Pediatr Blood Cancer 2015;62:208–213. © 2014. The Authors. Pediatr Blood & Cancer published by Wiley Periodicals, Inc.

Osteosarcoma (OS) is the most common malignant bone tumor affecting children and adolescents. Many patients are treated with a combination of chemotherapy, resection, and limb salvage protocols. Surgical reconstructions after tumor resection include structural allografts, non-cemented endoprostheses, and distraction osteogenesis (DO), which require direct bone formation. Although cisplatin (CDP) is extensively used for OS chemotherapy, the effects on bone regeneration are not well studied. The effects of CDP on direct bone formation in DO were compared using two dosing regimens and both C57BL/6 (B6) and tumor necrosis factor receptor 1 knockout (TNFR1KO) mice, as CDP toxicity is associated with elevated TNF levels. Detailed evaluation of the five-dose CDP regimen (2 mg/kg/day), demonstrated significant decreases in new bone formation in the DO gaps of CDP treated versus vehicle treated mice (p

Human genetic variation contributes to differences in susceptibility to HIV-1 infection. To search for novel host resistance factors, we performed a genome-wide association study (GWAS) in hemophilia patients highly exposed to potentially contaminated factor VIII infusions. Individuals with hemophilia A and a documented history of factor VIII infusions before the introduction of viral inactivation procedures (1979-1984) were recruited from 36 hemophilia treatment centers (HTCs), and their genome-wide genetic variants were compared with those from matched HIV-infected individuals. Homozygous carriers of known CCR5 resistance mutations were excluded. Single nucleotide polymorphisms (SNPs) and inferred copy number variants (CNVs) were tested using logistic regression. In addition, we performed a pathway enrichment analysis, a heritability analysis, and a search for epistatic interactions with CCR5 Δ32 heterozygosity. A total of 560 HIV-uninfected cases were recruited: 36 (6.4%) were homozygous for CCR5 Δ32 or m303. After quality control and SNP imputation, we tested 1 081 435 SNPs and 3686 CNVs for association with HIV-1 serostatus in 431 cases and 765 HIV-infected controls. No SNP or CNV reached genome-wide significance. The additional analyses did not reveal any strong genetic effect. Highly exposed, yet uninfected hemophiliacs form an ideal study group to investigate host resistance factors. Using a genome-wide approach, we did not detect any significant associations between SNPs and HIV-1 susceptibility, indicating that common genetic variants of major effect are unlikely to explain the observed resistance phenotype in this population.

Objective To develop criteria for the classification of macrophage activation syndrome (MAS) in patients with systemic juvenile idiopathic arthritis (JIA). Methods A multistep process, based on a combination of expert consensus and analysis of real patient data, was conducted. A panel of 28 experts was first asked to classify 428 patient profiles as having or not having MAS, based on clinical and laboratory features at the time of disease onset. The 428 profiles comprised 161 patients with systemic JIA-associated MAS and 267 patients with a condition that could potentially be confused with MAS (active systemic JIA without evidence of MAS, or systemic infection). Next, the ability of candidate criteria to classify individual patients as having MAS or not having MAS was assessed by evaluating the agreement between the classification yielded using the criteria and the consensus classification of the experts. The final criteria were selected in a consensus conference. Results Experts achieved consensus on the classification of 391 of the 428 patient profiles (91.4%). A total of 982 candidate criteria were tested statistically. The 37 best-performing criteria and 8 criteria obtained from the literature were evaluated at the consensus conference. During the conference, 82% consensus among experts was reached on the final MAS classification criteria. In validation analyses, these criteria had a sensitivity of 0.73 and a specificity of 0.99. Agreement between the classification (MAS or not MAS) obtained using the criteria and the original diagnosis made by the treating physician was high (κ = 0.76). Conclusion We have developed a set of classification criteria for MAS complicating systemic JIA and provided preliminary evidence of its validity. Use of these criteria will potentially improve understanding of MAS in systemic JIA and enhance efforts to discover effective therapies, by ensuring appropriate patient enrollment in studies.

Abstract 3681 Background: Pediatric Immune Thrombocytopenia (ITP) has an incidence of 4–6/100,000 with 1/3 of cases becoming chronic. Treatment choice is arbitrary, because few studies are powered to identify predictors of therapy response. Increasingly, rituximab is becoming a treatment of choice in those refractory to other therapies (Neunert CE, et al. Pediatr Blood Cancer 2008; 51(4):513). Previous studies in ITP have not examined predictors of response to rituximab or whether response to prior treatments predicts response. Objective: To evaluate univariate and multivariable predictors of platelet count response to rituximab. Methods: After local IRB approval, 550 patients with chronic ITP enrolled in the longitudinal, North American Chronic ITP Registry (NACIR) between January 2004 and June 2010. Eligibility included: ages 6 months-18 years at ITP diagnosis, clinical diagnosis of ITP, and ITP duration >6 months. Primary ITP was defined as isolated thrombocytopenia without associated conditions. Secondary ITP included those patients with immune thrombocytopenia associated with other immune-mediated medical conditions, including Evans Syndrome. Treatment response was defined as a post-treatment platelet count ≥50,000/uL within 16 weeks of rituximab and within 14 days of steroids. Steroids were prescribed as 1–4 mg/kg prednisone or adult equivalent over 4–14 days with or without taper. The NACIR captured treatment responses both retrospectively prior to enrollment and then prospectively, and both periods were included in this analysis. The multivariable logistic regression modeling process utilized SAS 9.1 using binary variables which were either significant in the univariate analysis or clinically important. A backwards elimination procedure was used to select the final model. Results: Seventy-six (13.8%) patients were treated with rituximab. Demographics of the patients treated with rituximab include: 42% male; 81% Caucasian, 17% Black, and 2% Asian. The mean age at diagnosis of ITP was 8.4 ± SD 5.1 years. The median platelet count at diagnosis of acute ITP was 10,000/uL (IQR 5,000-20,000/uL). 19 (25%) patients had secondary ITP or Evans syndrome. Treatment with rituximab had an overall response rate of 63.2% (48/76). Univariate predictors of response to rituximab are shown in Table I. The strongest univariate predictor of response to rituximab was response to steroids. Gender, ethnicity, and race were not predictive of response to rituximab. Furthermore, other variables which did not predict rituximab response include: history of a bleeding score ≥3 (Buchanan and Adix, J Pediatr 2002; 141: 683), symptoms ≥1 month prior to ITP diagnosis, older age (age >5 years), platelets ≥20,000/uL at acute ITP diagnosis, and a positive ANA. In multivariable analysis, response to steroids remained a strong predictor of response to rituximab with an OR 6.2 (95% CI 1.8–21.3, p=0.004). Secondary ITP also remained a strong a predictor of a positive response to rituximab with an OR 5.9 (95% CI 1.2–33.3, p=0.03). Conclusion: In the NACIR, response to steroids and secondary ITP were strong predictors of response to rituximab, a finding not previously reported in children or adults. Although this finding requires further validation, this result may provide evidence that rituximab should be most considered in patients previously responsive to steroids. Disclosures: Off Label Use: Rituximab for chronic ITP. Lambert:Cangene: Membership on an entity's Board of Directors or advisory committees. Klaassen:Novartis: Research Funding; Cangene: Research Funding. Neufeld:Novartis, Inc: Research Funding.

The majority of Osteosarcoma (OS) patients are treated with a combination of chemotherapy, resection, and limb salvage protocols. These protocols include distraction osteogenesis (DO), which is characterized by direct new bone formation. Cisplatin (CDP) is extensively used for OS chemotherapy and recent studies, using a mouse DO model, have demonstrated that CDP has profound negative effects on bone repair. Recent oncological therapeutic strategies are based on the use of standard cytotoxic drugs plus an assortment of biologic agents. Here we demonstrate that the previously reported CDP-associated inhibition of bone repair can be modulated by the administration of a small molecule p53 inducer (nutlin-3). The effects of nutlin-3 on CDP osteotoxicity were studied using both pre- and post-operative treatment models. In both cases the addition of nutlin-3, bracketing CDP exposure, demonstrated robust and significant bone sparing activity (p 0.01-0.001). In addition the combination of nutlin-3 and CDP induced equivalent OS tumor killing in a xenograft model. Collectively, these results demonstrate that the induction of p53 peri-operatively protects bone healing from the toxic effects of CDP, while maintaining OS toxicity. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1716-1724, 2016.

Patients with Langerhans cell histiocytosis (LCH) may behave differently depending on what sites are involved and the response or lack of response to earlier therapies. Therapy for high-risk patients or those with multiple reactivations continues to be challenging because of variable response rates and frequent toxicities. The goals of this study were to determine the long-term disease free survival in children with high-risk or multiply reactivated LCH treated with 2-CDA, and the toxicity of low dose continuous infusion (CI). Ten children with multiple reactivations or high-risk disease as defined by the Histiocyte Society were treated with CI 2-CDA and were evaluable for response and toxicity assessment. The starting dose of 2-CDA was 5 mg/M(2)/day for 3 days and escalated to 6.5 mg/M(2)/day for 3 days if tolerated. The maximum number of courses of 2-CDA per patient was limited to six. Fifty-two courses of 2-CDA were administered without difficulty. After the patient demonstrated no acute toxicity with the first administration of 2-CDA, the subsequent doses were given at home to all but one patient. All 10 patients had a clinical response, 9 documented by radiographic, or changes in physical exam or review of systems. Toxicity was limited to myelosuppression. Seven of the 10 patients required no additional therapy and remain disease free a median of 50 months from completing therapy. The three remaining patients are currently disease free after receiving other therapy. Further studies are needed to determine the role of 2-CDA in this patient population. 2-CDA can be given safely using home therapy, and may effective even in high-risk patients.

Acquired von Willebrand factor (vWF) disease is associated with a decrease in the amount of circulating high molecular weight (HMW) vWF multimers. vWF has not been previously investigated in children on extracorporeal membrane oxygenation (ECMO) support. We hypothesized that HMW vWF multimers and vWF activity decrease over the course of ECMO support in these patients. This prospective, single center, observational, cohort pilot study was carried out between December 2010 and April 2011 and included patients 0 to 18 years old requiring ECMO support at our institution. Blood samples were tested for various aspects of vWF. Mean and standard deviation were estimated for vWF activity and multimers, whereas a generalized linear model was developed to estimate multimer changes over time.The study included six pediatric patients. The mean age of the patients was 54.9 ± 55.3 (mean ± standard deviation) months. The mean HMW vWF multimer percentage was 23.4 ± 7.3 in the pre-ECMO samples and significantly decreased over time (p

In this issue of Blood, Donadieu et al present what may be the most encouraging data to date on a group of patients with Langerhans cell histiocytosis (LCH), which historically has poor disease-free survival and poor overall survival.

PURPOSE To determine the maximum-tolerated dose (MTD) and dose-limiting toxicity of topotecan when combined with cyclophosphamide in pediatric patients with recurrent or refractory malignant solid tumors. PATIENTS AND METHODS A total of 33 patients received cyclophosphamide (250 mg/m2/dose) followed by topotecan in escalating doses (0.6 to 0.75 mg/m2/dose), each given as a 30-minute infusion daily for 5 days. A total of 154 fully assessable treatment courses were given to these patients. RESULTS Neutropenia was the dose-limiting toxicity of the therapy at both topotecan dose levels. The addition of filgrastim allowed escalation of the topotecan dose to the 0.75-mg/m2 level with acceptable neutropenia. Other significant toxicities were anemia and thrombocytopenia. Nonhematopoietic toxicity of grades > or = 3 was not observed. Responses were reported in patients with Wilms' tumor (one complete response [CR], one partial response [PR]), neuroblastoma (one CR, one PR), rhabdomyosarcoma (one PR), and osteosarcoma (one PR). Pharmacokinetic studies indicate that cyclophosphamide administered on the schedule used in this study did not alter topotecan disposition on day 5. As with previous studies, a pharmacodynamic relation between systemic exposure and myelosuppression was noted. CONCLUSION The combination of topotecan and cyclophosphamide shows activity in a wide variety of pediatric solid tumors and can be given with acceptable hematopoietic toxicity with the use of filgrastim support. We recommend that pediatric phase II trials use cyclophosphamide 250 mg/m2 followed by topotecan 0.75 mg/m2 daily for 5 days with filgrastim for amelioration of neutropenia.

Background Pediatric patients with Langerhans cell histiocytosis (LCH) may become refractory to conventional therapy or present with repeated recurrences over several years. Current therapeutic options such as prednisone, vinblastine, etoposide, and cyclosporine are associated with significant acute toxicities and late effects. Recent reports suggested that 2-chlorodeoxyadenosine (2-CDA) may be an effective agent in adults with LCH. The purpose of this study was to determine the safety and efficacy of 2-CDA in children with LCH. Methods This report presents the data collected from the first three patients that have completed this trial. Patients were enrolled in a prospective study after informed consent was obtained. Patients had a confirmed diagnosis of LCH that had recurred several times or not responded to standard therapy. Patients were given a starting dose of 5 mg/M2 of daily continuous infusion for three days duration. Two patients had their dose increased to 6.5 mg/M2/day. A total of 4–6 courses were given, and courses were repeated every 3–4 weeks. Thirteen of fifteen courses were given as outpatients at home. Results Each patient completed therapy with myelosuppression the primary toxicity. Pt. 1 initially received a higher dose of 2-CDA and developed sepsis. The dose was reduced to current study levels and no other incidence of infection, fever, and neutropenia, or blood product transfusion was required. All three patients are free of active disease 10–18 months after completing 2-CDA. Conclusion Three patients with LCH refractory to standard therapy had CR to 2-CDA, given at 5–6.5 mg/M2/day for 3 days, without significant toxicity. Med. Pediatr. Oncol. 29:288–292, 1997. © 1997 Wiley-Liss, Inc.

PURPOSE To present two patients as illustrations of the risk of developing secondary acute myelogenous leukemia (sAML) when theoretically safe doses of etoposide (VP-16) are used. PATIENTS AND METHODS Patient no. 1 was a 15-year-old white girl diagnosed with stage IIa Hodgkin's disease. She was treated with a combination of vincristine, doxorubicin, bleomycin, and VP-16 (2 g/m2 total) over 4 months, followed by 25.5 Gy of involved-field radiotherapy. Patient no. 2 was an 11-year-old white boy diagnosed with virus-associated hemophagocytic syndrome (VAHS). He was treated with VP-16 intravenously (IV) and orally (0.3 g and 2.8 g/m2, respectively). RESULTS Patient no. 1 developed AML 16 months from the diagnosis of Hodgkin's disease. Patient no. 2 developed AML 26 months from diagnosis. Both bone marrows were consistent with French-American-British (FAB) M4 disease. Both patients had abnormalities of the long arm of chromosome 11. CONCLUSION The use of low-dose or oral VP-16 can be associated with the development of sAML. Clinicians should be cautious in the use of VP-16 in low-risk diseases.

Studies of the effects of yogurt on immunity and atopic diseases have suggested improvements in cytokine (interleukin-2 and interferon-gamma) responses and clinical scores in patients with allergic rhinitis. This study compares prospectively immune parameters of participants who received 16 oz of yogurt versus 16 oz of milk/day in a randomized cross-over design. Yogurt that contained live, active Lactobacillus bulgaricus and Streptococcus thermophilus or 2% milk was consumed for one month each. Twenty otherwise healthy adults with atopic histories documented by skin testing were enrolled. Immune studies were performed at the beginning and end of the two 1-month study phases, separated by a 2-week washout period. These studies included measurements of cellular, humoral, and phagocytic function. No adverse events were noted in either group. No significant improvements in any immune parameter were noted. The consumption of yogurt that contained the live active bacteria L bulgaricus and S thermophilus does not appear to enhance immune function in atopic individuals at the dosage and duration used in this study.

Osteosarcoma (OS) is the most common malignant bone tumor affecting children and adolescents. Many patients are treated with a combination of chemotherapy, resection, and limb salvage protocols. Surgical reconstructions after tumor resection include structural allografts, non-cemented endoprostheses, and distraction osteogenesis (DO), which require direct bone formation. Although cisplatin (CDP) is extensively used for OS chemotherapy, the effects on bone regeneration are not well studied. The effects of CDP on direct bone formation in DO were compared using two dosing regimens and both C57BL/6 (B6) and tumor necrosis factor receptor 1 knockout (TNFR1KO) mice, as CDP toxicity is associated with elevated TNF levels. Detailed evaluation of the five-dose CDP regimen (2 mg/kg/day), demonstrated significant decreases in new bone formation in the DO gaps of CDP treated versus vehicle treated mice (p 0.001). Further, no significant inhibitory effects from the five-dose CDP regimen were observed in TNFR1KO mice. The two-dose regimen significantly inhibited new bone formation in B6 mice. These results demonstrate that CDP has profound short term negative effects on the process of bone repair in DO. These data provide the mechanistic basis for modeling peri-operative chemotherapy doses and schedules and may provide new opportunities to identify molecules that spare normal cells from the inhibitory effects of CDP.

In haemophilia patients with well-established high-titer inhibitors, even seemingly minor acute bleeding episodes or surgical procedures may become refractory to treatment and transform into limb- or life-threatening situations. In the absence of evidence-based treatment guidelines, this article presents 10 cases of difficult to control acute and surgical bleeding and offers consensus opinions regarding their management from a panel of experienced haemophilia treaters.

Nat. Genet. 47, 1326–1333 (2015); published online 12 October 2015; corrected after print 7 December 2015 In the version of this article initially published, two patients were stated on page 5 to have been excluded owing to insufficient follow-up data. These patients were included in the final analysis, but two additional patients were excluded owing to the presence of Noonan syndrome.

Wilms' tumor (WT) is associated with chromosomal deletions and loss of heterozygosity (LOH) of alleles at 11p13. The authors report the youngest known patient with diffusely anaplastic WT and, to their knowledge, the first case to demonstrate telomeric fusions as a chromosomal mechanism for the loss of bands 11p13 and 11p15 in WT. Recurrent clonal telomeric association (tas) initiated breakage/fusion cycles that resulted in deletions of chromosome bands 11p15, 11p13, and subsequently, the entire short arm of chromosome 11. In addition, tas involving the long arms of chromosomes 7 and 9 resulted in the subsequent deletion of the long arm of chromosome 7. This report expands the spectrum of chromosomal mechanisms that can account for the loss of alleles on the short arm of chromosome 11 in WT by providing evidence that the progressive loss of critical chromosome regions associated with tumor suppression may occur as a result of chromosomal instability initiated by tas. Cancer 1994; 74: 767-73.

Bleeding is a common event in many people, but when is it abnormal and when should further evaluation and diagnostic testing be performed? This review will highlight the three most common bleeding disorders and briefly describe their more common forms of presentation and management options. We will also discuss the role of local hemophilia treatment centers in assisting physicians around the state in managing these complex patients.

Type 3 von Willebrand disease (VWD) is a rare bleeding disorder with markedly decreased or absent von Willebrand factor (VWF) protein, accompanied by a parallel decrease in VWF function and factor VIII (FVIII) activity. The goal of this study was to describe the population of patients enrolled in the USA Centers for Disease Control Universal Data Collection (UDC) study with type 3 VWD, defined as a VWF:Ag of

Human immunodeficiency virus type-1 (HIV-1)-infected individuals exhibit functional impairment in various forms of cell-mediated cytotoxicities (CMC) at all stages of disease. The purpose of this study was to determine (i) if peripheral blood mononuclear cells (PBMC) obtained from HIV-1-infected patients could be stimulated in vitro to yield lymphokine-activated killer (LAK) activity; (ii) if non-MHC-restricted gp120-specific CMC could be preserved; and (iii) what effect zidovudine (AZT) would have on LAK activity. Fourteen asymptomatic HIV-1 seropositive adults and five healthy seronegative adults (controls) were evaluated. PBMCs were isolated and incubated in media or supplemented with IL-2 for 4 or 72 hr. Lysis of the NK resistant target cell line, Daudi, was similar for the control and experimental group. The increase in activity after stimulation was elevated to a similar degree in both seronegative and seropositive groups (P less than 0.001). LAK activity was significantly decreased (P = 0.011) when AZT was added to LAK cultures. In addition, virus production may not have been completely inhibited by AZT in LAK cultures. Thus, PBMCs from asymptomatic HIV-1-infected patients could be stimulated to yield LAK activity. However, AZT can impair LAK generation. It is unclear if LAK activation results in virus production that cannot be inhibited by AZT in this system. Further definition in other patient populations is required prior to applying this information to clinical trials.

Purpose To determine the outcomes, with particular attention to toxicity, of children with Down syndrome (DS) and acute myeloid leukemia (AML) treated on Pediatric Oncology Group (POG) protocol 9421. Patients and Methods Children with DS and newly diagnosed AML (n = 57) were prospectively enrolled onto the standard-therapy arm of POG 9421 and were administered five cycles of chemotherapy, which included daunorubicin 135 mg/m2 and mitoxantrone 80 mg/m2. Outcomes and toxicity were evaluated prospectively and were compared with the non-DS–AML cohort (n = 565). A retrospective chart review was performed to identify adverse cardiac events. Results In the DS-AML group, 54 patients (94.7%) entered remission. One experienced induction failure and two died. Of the 54 who entered remission, three relapsed and six died as a result of other causes. The remission induction rate was similar in the non-DS–French-American-British (FAB) M7 (91.7%) and non-DS–non-M7 (89.3%) groups. The 5-year overall survival was significantly better in the DS-AML group (78.6%) than in the non-DS–M7 (36.3%) or the non-DS–non-M7 (51.8%) groups (P < .001). No age-related difference in 5-year, event-free survival was seen between patients younger than 2 years (75.8%) and those aged 2 to 4 years (78.3%). Symptomatic cardiomyopathy developed in 10 patients (17.5%) with DS-AML during or soon after completion of treatment; three died as a result of congestive heart failure. Conclusion The POG 9421 treatment regimen was highly effective in both remission induction and disease-free survival for patients with DS-AML. However, there was a high incidence of cardiomyopathy, which supports current strategies for dose reduction of anthracyclines in this patient population.

Achieving hemostasis in patients with hemophilia A or B is complicated by the presence of inhibitors and is made even more difficult when these individuals require surgery. Over a 4-year period, 6 patients with inhibitors to factor VIII and 1 patient with inhibitors to factor IX underwent surgery or invasive procedures at our institution. A total of 26 procedures were performed, primarily using the bypassing agent FEIBA for bleeding control. Excellent hemostasis was obtained in all cases, adding to accumulating data indicating that FEIBA is safe and effective in hemophilia patients with inhibitors who require surgery.

Lupus anticoagulants (LAs) represent a diverse group of antibodies directed against phospholipids. Patients with LAs may be free of symptoms but can have thrombotic complications including stroke, placental infarction, and fetal loss. Rarely hemorrhagic symptoms have been reported. We describe six previously healthy children who were first seen with clinical bleeding and prolonged activated partial thromboplastin time. Laboratory evaluation revealed positive results on mixing studies and evidence of phospholipid dependence of the anticoagulant, suggesting LAs. Four of six patients had anticardiolipin antibodies, and all four who were tested had reduced factor II activity levels. In all patients, bleeding symptoms resolved spontaneously within 3 months, and laboratory findings returned to normal within 6 months. The hemorrhagic LA syndrome should be considered in previously healthy children with new-onset bleeding and prolonged activated partial thromboplastin time. This clinical entity probably represents pathogenic mechanism distinct from thrombotic LA syndromes.

Purpose Prognosis is poor for Ewing sarcoma patients with metastasis at diagnosis. We intensified a five-drug therapy (ifosfamide, etoposide alternated with vincristine, doxorubicin, and cyclophosphamide) using filgrastim but not stem-cell support. We studied topotecan alone and combined with cyclophosphamide in therapeutic windows before the five-drug therapy. A randomly assigned proportion of patients received amifostine as a cytoprotective agent. Patients and Methods Eligible patients were ≤ 30 years old and had histologically proven Ewing sarcoma or primitive neuroectodermal tumor (PNET) and metastasis at diagnosis. Chemotherapeutic cycles began every 21 days, after recovery from toxicities. Results One hundred ten of the 117 patients enrolled were eligible. Thirty-six patients received initial topotecan. Three had partial responses (PRs), and 17 had progressive disease (PD). Thirty-seven patients were administered topotecan and cyclophosphamide; 21 of these patients achieved PR, and one patient had PD. In a randomly assigned group of 69 patients, amifostine did not provide myeloprotection, which was measured by absolute neutrophil count, platelet count, or cycle intervals. The best responses to the overall therapy included 45 complete responses, 41 PRs, stable disease in 14 patients, and PD in five patients. For all patients, the 2-year event-free survival (EFS) rate was 24% (± 4%), and the overall survival rate was 46% (± 5%). For the 39 patients with isolated pulmonary metastases, the 2-year EFS rate was 31% (± 7%) compared with 20% (± 5%) for patients with more widespread disease. Conclusion Topotecan had limited activity in patients with Ewing sarcoma or PNET metastatic at diagnosis. The topotecan-cyclophosphamide combination was active. Amifostine was not myeloprotective. Overall results showed no improvement compared with previous studies.

Sinus histiocytosis with massive lymphadenopathy (SHML) is a histiocytic disorder affecting children and adults. It usually presents as markedly enlarged lymph nodes that require surgical biopsy for confirmation. This lesion is usually self-limited but can present in areas that can cause significant morbidity or disfigurement. We report a case that required therapy due to the severe disfigurement but was resistant till treated with dexamethasone. This case illustrates that SHML may be resistant to prednisone but still be sensitive to dexamethasone.

Patients with Langerhans cell histiocytosis (LCH) may behave differently depending on what sites are involved and the response or lack of response to earlier therapies. Therapy for high-risk patients or those with multiple reactivations continues to be challenging because of variable response rates and frequent toxicities. The goals of this study were to determine the long-term disease free survival in children with high-risk or multiply reactivated LCH treated with 2-CDA, and the toxicity of low dose continuous infusion (CI). Ten children with multiple reactivations or high-risk disease as defined by the Histiocyte Society were treated with CI 2-CDA and were evaluable for response and toxicity assessment. The starting dose of 2-CDA was 5 mg/M(2)/day for 3 days and escalated to 6.5 mg/M(2)/day for 3 days if tolerated. The maximum number of courses of 2-CDA per patient was limited to six. Fifty-two courses of 2-CDA were administered without difficulty. After the patient demonstrated no acute toxicity with the first administration of 2-CDA, the subsequent doses were given at home to all but one patient. All 10 patients had a clinical response, 9 documented by radiographic, or changes in physical exam or review of systems. Toxicity was limited to myelosuppression. Seven of the 10 patients required no additional therapy and remain disease free a median of 50 months from completing therapy. The three remaining patients are currently disease free after receiving other therapy. Further studies are needed to determine the role of 2-CDA in this patient population. 2-CDA can be given safely using home therapy, and may effective even in high-risk patients.

Background Determination of the absolute neutrophil count (ANC) is a critical test prior to initiation of chemotherapy and is a standard component of cancer therapy protocols. Automated determination of this parameter potentially shortens the turnaround time necessary between specimen phlebotomy and chemotherapy infusion in an outpatient setting. However, there are certain factors that can lead to spuriously elevated or lowered ANCs, possibly leading to inappropriate dosage. We therefore compared ANC results in a series of samples in which both automated and manual results were available. Procedure Sets of 111 specimens, tested over a 1-month period, had matched automated and manual ANC results available for initial retrospective analysis. An additional set of 35 specimens with ANCs of

PURPOSE: To determine the response rate of the combination of cyclophosphamide and topotecan in pediatric patients with recurrent or refractory malignant solid tumors. PATIENTS AND METHODS: A total of 91 pediatric patients, 83 of whom were fully assessable for response and toxicity, received cyclophosphamide (250 mg/m2/dose) followed by topotecan (0.75 mg/m2/dose), each given as a 30-minute infusion daily for 5 days. All patients received filgrastim (5 mcg/kg) daily until the absolute neutrophil count (ANC) was ≥ 1,500 μL after the time of the expected ANC nadir. RESULTS: A total of 307 treatment courses were given to the 83 fully assessable patients. Responses (complete response plus partial response) were seen in rhabdomyosarcoma (10 of 15 patients), Ewing’s sarcoma (six of 17 patients), and neuroblastoma (six of 13 patients). Partial responses were seen in two of 18 patients with osteosarcoma and in one patient with a Sertoli-Leydig cell tumor. Twenty-three patients had either minor responses (n = 6) or stable disease (n = 17); the median number of courses administered to patients with partial or complete response was six (range, two to 13 courses), and the median administered to those with stable disease was three (range, one to 11 courses). The toxicity of the combination was limited principally to the hematopoietic system. Of 307 courses, 163 (53%) were associated with grade 3 or 4 neutropenia, 84 (27%) with grade 3 or 4 anemia, and 136 (44%) with grade 3 or 4 thrombocytopenia. Despite the severe myelosuppression, only 34 (11%) of 307 courses were associated with grade 3 or 4 infection. Nonhematopoietic toxicity of grades ≥ 3 was rare and consisted of nausea and vomiting (two courses), perirectal mucositis (one course), transaminase elevation (one course), and hematuria (two courses). CONCLUSION: The combination of cyclophosphamide and topotecan is active in rhabdomyosarcoma, neuroblastoma, and Ewing’s sarcoma. Stabilization of disease was seen in osteosarcoma, although objective responses were rare in this disease. The therapy can be given with acceptable hematopoietic toxicity with the use of filgrastim support.

Background Children with acute, severe cardiopulmonary compromise may require support with ECMO. Adequate anticoagulation without inducing life-threatening hemorrhage plays a critical role in the management of these patients. Recent data from adult studies suggest that patients undergoing cardiac bypass for coronary artery bypass grafting (CABG) often have reduced Factor XIII levels (FXIII). This relative FXIII deficiency may be predictive of hemorrhage or severe blood loss. Such studies have never been conducted in the pediatric population. Our primary objective will be to determine if a relative deficiency in FXIII occurs in children undergoing ECMO and to determine any time dependency of these changes. Our secondary objective will be to determine if blood loss and/or transfusion requirements during ECMO correlates with FXIII levels. Methods Single center ongoing study utilizing a prospective design involving pediatric patients (ages 0-18) undergoing ECMO. Samples for FXIII, D-Dimers, Fibrinogen and Thrombin Time are being drawn at designated time points as follows: prior to or during ECMO cannulation, 2 hours, 24 hours, 3-5 days and 14-21 days after initiation of ECMO and 1-3 days after discontinuation of ECMO. Mixed effects analysis of covariance (ANCOVA) will be used for data analysis. Results To date, fifteen patients have been enrolled and analyses have been conducted for n=7 patients with a total of 36 time points of data. Figure 1a and 1b show the mean and standard deviation (SD) of FXIII and Fibrinogen, respectively. Figure 1c shows the mean ratio of FXIII to Fibrinogen. Error bars represent 1 SD around the mean (central point). Conclusion and Significance This is the first pediatric study evaluating FXIII activity in children undergoing ECMO. Firm conclusions cannot be drawn with the interim analyses conducted to date. If variations in FXIII are found, our results will provide important information towards determining if children undergoing ECMO could potentially benefit from FXIII replacement, in turn minimizing bleeding complications and/or transfusion requirements often encountered with this treatment modality. Disclosures: No relevant conflicts of interest to declare.

The purpose of this study was to determine if KRN5500, a spicamycin derivative with a unique acyl tail, would induce programmed cell death (PCD) of myeloid leukemia cell lines and cryopreserved leukemic blasts from newly diagnosed children with acute leukemia (AL). Cells were incubated with varying concentrations (0-5 ng/ml) of KRN5500 and the percent PCD determined using a modified in situ end labeling (ISEL) technique with Klenow fragment. The percent PCD was calculated using the formula: Percent PCD (% PCD)=[number of apoptotic cells/(viable cells+apoptotic cells)]x100. DMSO (0.30% w/v) was added to the cells in culture as the positive control for PCD; the negative control was media or albumin. KRN5500 increased the amount of PCD significantly in all five of the tested cell lines; U937 41+/-1.8%, KG1a 40+/-0.3%, HEL 14+/-2.2%, HL-60 41+/-0. 9%, K562 36+/-2% (mean PCD+/-SD). Patient blasts exposed to KRN5500 had an increase in PCD when exposed to 2 ng/ml of agent from 2 to 8 h; acute myeloid leukemia patients 7.5+/-0.5% at 2 h to 43.5+/-1.6% at 8 h, and acute lymphocytic leukemia patients rose from 12.4+/-3.8% at 2 h to 29.9+/-11.6% after 8 h (mean+/-SE). Overall the PCD for the patient samples was 3.7 versus 28+/-4% at 2 and 8 h, respectively. PCD was proportional to the dose of KRN5500 and incubation time. Further pre-clinical and clinical studies are required.

IL-2 augments the ability of natural killer (NK) cells to kill myeloid leukemia cells in vitro, and may have a role in the eradication of minimal residual disease (MRD) in AML patients. The ability to enhance lysis of AML cells without the toxicity of IL-2 would be a significant improvement in the use of biologics against AML. Recent interest in IL-12 suggested that this cytokine might meet these criteria. The aim of this study was to evaluate the ability of IL-12 to enhance the in vitro lysis of the non-lymphoid leukemia cell lines in a standard 51Chromium release assay. Effector cells from normal volunteers were incubated with varying concentrations of IL-12 or IL-2 for 18-20 h, then the 51Cr-labeled target cells from five different cell lines of AML origin were added for 4 h. Percent lysis was determined and plotted over four effector:target (E:T) ratios. Our results indicated that IL-12 was able to enhance lysis of all cell lines tested ator =5 units/ml. When IL-2 was added to the culture at a low dose along with IL-12, there appeared to be a synergistic effect. Although anti-gamma interferon was able to inhibit the cytolytic potential of effectors activated by IL-12, the lysis could not be completely blocked. Thus, it appears that IL-12 has the ability to stimulate NK lysis indirectly through the induction of gamma interferon as well as an alternate mechanism not related to gamma interferon. Thus, IL-12 may have a beneficial role in the treatment of non-lymphoid leukemia.

Background. Skeletal complications are responsible for significant morbidity in Gaucher patients. Plain radiographs have been unreliable in assessing bone marrow infiltration and activity. A way to assess bone marrow improvement is needed during enzyme therapy. Objective. The purpose of this paper is to assess the usefulness of MR in following improvement of abnormal bone marrow in Gaucher patients on enzyme therapy. Materials and methods. Three patients aged 2, 7, and 24 years underwent serial MR scans of the lower extremities before and during treatment with Alglucerase (two patients) and Imiglucerase (one patient). T1-weighted, T2-weighted, STIR and FSE T2-weighted images were utilized. Two patients were imaged after 16 months of therapy, and one patient was imaged after 6 months of therapy. Results. All patients had improvement in marrow signal consistent with partial reconversion to fatty marrow during treatment. The findings were more marked after prolonged therapy. T1-weighted images demonstrated findings most clearly. Conclusion. MR consistently showed improvement in marrow signal in Gaucher patients on enzyme therapy. As smaller doses of enzyme therapy are the trend, MR can be utilized to determine if therapy is effecting a change in the bone marrow.

Summary. We present a patient with haemophilia undergoing cardiac surgery treated with continuous infusion factor VIII.

Abstract 2509 Background: Chronic pediatric immune thrombocytopenia (ITP) has an incidence of 1–2/100,000. Due to its low incidence, large studies in pediatric chronic ITP are difficult. This registry includes patients from 16 sites in the US and Canada and represents one of the largest longitudinal datasets of children/adolescents with chronic ITP. Objective: To describe the North American Chronic ITP Registry (NACIR) study population and evaluate univariate predictors of platelet count response to therapies, including IVIG, anti-D globulin (anti-D), steroids (5–14 day course), and splenectomy. Registry methods and patient characteristics: After local IRB approval, 550 patients with chronic ITP enrolled in the NACIR between January 2004 and June 2010. Eligibility included: ages 6 months-18 years at ITP diagnosis, clinical diagnosis of ITP, and ITP duration >6 months. Primary ITP was defined as isolated thrombocytopenia without associated conditions. Secondary ITP included those patients with immune thrombocytopenia associated with other immune-mediated medical conditions, including Evans Syndrome. Treatment response was defined as a post-treatment platelet count ≥50,000/uL within 7 days of IVIG, 10 days of anti-D, 14 days of steroids, and 30 days of splenectomy. 365 subjects had at least one 6 month follow-up report after enrollment; median duration of follow-up was 2.1 yrs. Demographics of participants include: 46% male; 84% Caucasian, 7% Black, and 7% Asian; and 20% Hispanic. Mean age at diagnosis of acute ITP was 8.7 ± SD 5.2 years. At the time of enrollment in NACIR, subjects had received a median of 2 prior treatments (range 0–7). Results: The median platelet count at diagnosis of acute ITP was 11,000/uL (IQR 6,000–31,000/uL) and at chronic ITP was 35,000/uL (IQR 18,000–66,000/uL). 69 (12.5%) patients had secondary ITP or Evans syndrome. Of those tested, 25.6% (98/359) of patients had a positive ANA (titer > 1:40), and 75/337 (22.3%) had a positive direct anti-globulin test (DAT). 27.5% of patients had an antecedent viral illness. Of the 550 subjects, 2 (0.4%) experienced life-threatening bleeding. Patients were treated as follows: 259 (47.1%) with steroids, 253 (46%) with IVIG, 189 (34.4%) with anti-D, and 64 (11.6%) with splenectomy. Overall responses to therapy included: 69.1% response to steroids, 74.3% response to IVIG, 66.7% response to anti-D, and 85.9% response to splenectomy. Univariate predictors of response to treatments are shown in Table I. Higher platelet count at chronic ITP diagnosis and DAT positive predicted a platelet response to a short course of steroids in univariate analysis. This was confirmed in multivariable analysis of potential confounders, using logistic regression with a backwards elimination procedure. Response to one type of therapy was often strongly associated with a response to a second therapy. Gender, ethnicity, race, older age, and platelets ≥20,000/uL at acute ITP diagnosis were not associated with response to any single therapy. Conclusion: The demographics and laboratory findings of the large, well characterized NACIR population are consistent with other reports of young people with chronic ITP. The novel finding that DAT positivity predicts steroid response, even with multivariable adjustment for confounders, provides evidence that the NACIR is a robust and useful tool for trying to predict response to ITP treatment strategies. Disclosures: Klaassen: Novartis: Research Funding; Cangene: Research Funding. Lambert: Cangene: Membership on an entity's Board of Directors or advisory committees.