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No widely accepted method exists to evaluate pediatric hematology oncology patients for the risk of venous thromboembolism (VTE) and the need for prophylaxis. The use of a VTE risk-assessment tool and standardized guidelines for prophylaxis could increase the use of appropriate prophylaxis and reduce the number of VTEs in patients, thereby decreasing morbidity, mortality, hospitalization, and cost. The purpose of this project was to implement and assess the compliance of a pediatric-specific VTE risk-assessment tool in hospitalized pediatric, adolescent, and young adult hematology oncology patients. From the 114 pediatric, adolescent, and young adult patients requiring assessment, 91 (80%) VTE assessments were completed and 87 (96%) were completed accurately. Eighty percent of the at-risk patients were ordered VTE prophylaxis. The use of a VTE risk-assessment tool in pediatric hematology oncology patients is a feasible way to assess patients for their risk of developing a VTE.

Children with sickle cell anemia (SS) have an increased risk for cerebral vasculopathy with stroke (CVA) and cognitive impairment. The present study examines the extent to which adding positron emission tomography (PET) to magnetic resonance imaging (MRI) can improve the detection of cerebral vasculopathy. Whereas MRI has been the prime modality for showing anatomical lesions, PET excels at assessing the functional metabolic state through glucose utilization 2-deoxy-2 [18F] fluoro-D-glucose (FDG) and microvascular blood flow ([15O]H2O). Forty-nine SS children were studied. Among them, 19 had clinically overt CVA, 20 had life-threatening hypoxic episodes or soft neurologic signs, and 10 were normal based on neurological history and examination. For the entire sample of 49 subjects, 30 (61%) had abnormal MRI findings, 36 (73%) had abnormal PET findings, and 44 (90%) showed abnormalities on either the MRI or the PET or both. Of the 19 subjects with overt CVA, 17 had abnormal MRI (89%), 17 had abnormal PET (89%), and 19 (100%) had either abnormal MRI or PET or both. Among the 20 subjects with soft neurologic signs, 10 (50%) had abnormal MRI, 13 (65%) had abnormal PET, and 17 (85%) had abnormal MRI and/or PET. Six (60%) of the 10 neurologically normal subjects had abnormal PET. Among the 30 subjects with no overt CVA, 25 (83%) demonstrated imaging abnormalities based on either MRI or PET or both, thus, silent ischemia. Lower than average full-scale intelligence quotient (FSIQ) was associated with either overt CVA or silent ischemic lesions. Four subjects who received chronic red blood cell transfusion showed improved metabolic and perfusion status on repeat PET scans. In conclusion, (1) the addition of PET to MRI identified a much greater proportion of SS children with neuroimaging abnormalities, particularly in those who had no history of overt neurologic events. (2) PET lesions are more extensive, often bihemispheric, as compared with MRI abnormalities. (3) PET may be useful in management as a tool to evaluate metabolic improvement after therapeutic interventions, and (4) the correlation of PET abnormalities to subsequent stroke or progressive neurologic dysfunction requires further study.

In vivoneulrophil phagocytosis was demonstrated by transmission electron microscopy (TEM) in the peripheral blood of two half-sibs with hereditary thrombocylopenia. These sibs have had a lifetime documented history of thrombocytopenia. Light microscopy morphology and histochemistry studies of blood and marrow were normal, similar studies of blood from available members of the kinship were also normal. Scanning electron microscopy (SEM) of platelets from each member of the kinship showed normal dendritic and spreading formation. In the TKM thin sections of platelet huffy coats, neutrophil ingestion of platelets was common and all stages of the phagocytic process were noted—from plalelel-neutrophil intimacy to the formation of myelin bodies in phagosomes. The clinical courses over a 10-year period were mild, requiring rare therapeutic interventions. The chronic thrombocytopenia, lengthy mild course, modestly elevated platelet-associated immune globulin, normal aggregation and survival studies, and autoimmune neulrophil reaction to platelets allowed classification of these patients as hereditary thrombocytopenia purpuras.

From mid-1967 to mid-1983, three hundred fifty surgical operations were performed on 163 patients with hemophilia A, without factor VIII inhibitor. One death occurred, in a patient with a serious head injury. Postoperative hemorrhages occurred after 23% of operations, but the incidence after surgery on the knee, 40%, was decidedly higher than the 15% incidence after operations at other sites. Concurrent plasma factor VIII levels were over 0.40 units/mL in 72% of instances and under 0.30 units/mL in only 15% of instances. The incidence of postoperative hemorrhage did not change over the study period despite a threefold increase in typical dosage of factor VIII (from 600 to 2,000 units/kg per operation) and doubling of typical trough factor VIII levels (from 0.37 units/mL to 0.70 units/mL). Circulating factor VIII levels apparently are not the sole determinants of postoperative bleeding in hemophilia A.(JAMA 1985;253:1279-1283)

Induction of immune tolerance in patients with severe hemophilia A and inhibitors to factor VIII was attempted by daily infusion of 50 U of factor VIII per kilogram of body weight without adjunctive immunosuppressive drugs. Modest initial anamnestic elevation of inhibitor levels occurred in six patients within the first month of therapy; inhibitor levels then fell sharply. The other six patients had no increase in inhibitor levels while on the study protocol. Inhibitors became undetectable within one to ten months in nine of the patients; they now receive smaller and less frequent infusions of factor VIII to maintain suppression. Inhibitors were not eradicated in three patients, who had the highest baseline and historic inhibitor levels. Ten patients gave consent for human immunodeficiency virus (HIV) testing; three had no antibody to HIV at the outset. Two of these patients seroconverted while on the protocol, one of whom had received only donor-screened, heat-treated factor VIII. Thus, the benefits of inhibitor suppression must be weighed against the risks of HIV seroconversion or transient elevation of inhibitor levels, as well as against the cost of the factor concentrate used.(JAMA 1988;259:65-68)

Pratt: Grifols, Inc: Research Funding; Bloodworks NW: Patents & Royalties: inventor on patents related to FVIII immunogenicity.

The formation of pathological anti-FVIII antibodies, referred to as “inhibitors”, is the most serious complication of therapeutic FVIII infusions, affecting up to one third of severe Hemophilia A (HA) patients. Intensive FVIII therapy, i.e. “Immune Tolerance Induction” (ITI), enables ~2/3 of treated patients to achieve peripheral tolerance to FVIII. FVIII inhibitor formation is a classical T-cell dependent adaptive immune response. As such, it requires help from the innate immune system. However, the roles of innate immune cells and mechanisms of inhibitor development versus immune tolerance, achieved with or without ITI therapy, are not well understood.

Peyvandi: Novo Nordisk: Speakers Bureau; Octapharma US: Honoraria; Novo Nordisk: Speakers Bureau; Shire: Speakers Bureau; Ablynx: Other: Member of Advisory Board, Speakers Bureau; Roche: Speakers Bureau; Grifols: Speakers Bureau; Sobi: Speakers Bureau; Kedrion: Consultancy; Grifols: Speakers Bureau; Octapharma US: Honoraria; Sobi: Speakers Bureau; Grifols: Speakers Bureau; Grifols: Speakers Bureau; Kedrion: Consultancy; Octapharma US: Honoraria; Octapharma US: Honoraria; Kedrion: Consultancy; Ablynx: Other: Member of Advisory Board, Speakers Bureau; Ablynx: Other: Member of Advisory Board, Speakers Bureau; Novo Nordisk: Speakers Bureau; Sobi: Speakers Bureau; Roche: Speakers Bureau; Shire: Speakers Bureau; Sobi: Speakers Bureau; Kedrion: Consultancy; Ablynx: Other: Member of Advisory Board, Speakers Bureau; Shire: Speakers Bureau; Novo Nordisk: Speakers Bureau; Roche: Speakers Bureau; Shire: Speakers Bureau; Grifols: Speakers Bureau; Kedrion: Consultancy; Ablynx: Other: Member of Advisory Board, Speakers Bureau; Shire: Speakers Bureau; Octapharma US: Honoraria; Sobi: Speakers Bureau; Roche: Speakers Bureau; Roche: Speakers Bureau; Novo Nordisk: Speakers Bureau. Palla:Grifols: Other: travel support; Pfizer: Other: travel support. Santagostino:Grifols: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees; CSL Behring: Membership on an entity's Board of Directors or advisory committees; Octapharma: Membership on an entity's Board of Directors or advisory committees; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees; Shire: Membership on an entity's Board of Directors or advisory committees; Kedrion: Membership on an entity's Board of Directors or advisory committees; Bioverativ: Membership on an entity's Board of Directors or advisory committees; Sobi: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees. Young:Novo Nordisk: Consultancy, Honoraria; Bioverativ: Consultancy, Honoraria; Bayer: Consultancy; CSL Behring: Consultancy, Honoraria; Kedrion: Consultancy; Genentech/Roche: Consultancy, Honoraria; Shire: Consultancy, Honoraria. Seth:Shire: Honoraria. Mancuso:Bayer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novo Nordisk: Consultancy, Membership on an entity's Board of Directors or advisory committees; Shire: Consultancy, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees; CSL Behring: Consultancy, Membership on an entity's Board of Directors or advisory committees; Kedrion: Consultancy; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Biotest: Membership on an entity's Board of Directors or advisory committees; Octapharma: Membership on an entity's Board of Directors or advisory committees. Mahlangu:Sanofi: Research Funding, Speakers Bureau; Roche: Consultancy, Research Funding, Speakers Bureau; LFB: Consultancy; NovoNordisk: Consultancy, Research Funding, Speakers Bureau; CSL Behring: Consultancy, Research Funding, Speakers Bureau; Chugai: Consultancy; Catalyst Biosciences: Consultancy, Research Funding; Biomarin: Research Funding, Speakers Bureau; Biogen: Research Funding, Speakers Bureau; Bayer: Research Funding; Amgen: Consultancy; Alnylam: Consultancy, Research Funding, Speakers Bureau; Shire: Consultancy, Research Funding, Speakers Bureau; Sobi: Research Funding, Speakers Bureau; Spark: Consultancy, Research Funding. Ewing:Hema Biologics: Honoraria; Novo Nordisk: Honoraria; CSL Behring: Honoraria; Grifols: Honoraria; Bayer: Honoraria; Shire: Honoraria; Genentech: Honoraria; Biogen: Research Funding. Male:Bayer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Octapharma: Speakers Bureau; Novo Nordisk: Speakers Bureau; Biotest: Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Shire: Speakers Bureau; SOBI: Speakers Bureau; CSL Behring: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. Majumdar:NIMHD: Research Funding. Manco-Johnson:CSL Behring: Honoraria; Biogentek: Honoraria; Novo Nordisk: Honoraria; Bayer AG: Honoraria, Research Funding; Baxalta, now part of Shire: Honoraria. Mazzucconi:Baxalta-Shire: Consultancy, Speakers Bureau; Bayer: Consultancy, Speakers Bureau; Novartis,: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Novo Nordisk: Consultancy, Speakers Bureau; CSL Behring: Consultancy, Speakers Bureau. Neme:Shire: Consultancy, Honoraria; Novonordisk: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Grifols: Consultancy, Honoraria; CSL Behring: Consultancy, Honoraria. Prezotti:Bayer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Bioverative: Membership on an entity's Board of Directors or advisory committees; Roche: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Shire: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Mannucci:Kedrion: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Grifols: Speakers Bureau; Bayer: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Baxalta/Shire: Speakers Bureau; Alexion: Speakers Bureau; Novo Nordisk: Speakers Bureau.

Ewing: Genentech: Honoraria; Shire: Honoraria; Bayer: Honoraria; Grifols: Honoraria; CSL Behring: Honoraria; Novo Nordisk: Honoraria; Hema Biologics: Honoraria; Biogen: Research Funding. Koenigs:Jansen: Research Funding; Gilead: Research Funding; Biotest: Research Funding, Speakers Bureau; Bayer: Consultancy, Research Funding, Speakers Bureau; Pfizer: Research Funding, Speakers Bureau; Intersero: Research Funding; CSL Behring: Consultancy, Research Funding; EU (IMI, FP7): Research Funding; Sobi: Consultancy, Research Funding, Speakers Bureau; Shire: Consultancy, Research Funding; Novo Nordisk: Consultancy, Speakers Bureau; Bioverativ: Consultancy; Roche/Chugai: Consultancy.

Introduction

Background:A major complication in severe hemophilia A is the formation of persistent neutralizing antibodies against factor(F) VIII, inhibitors, which render subsequent treatment ineffective. The presence of non-neutralizing anti-FVIII IgG antibodies (NNAs) before FVIII treatment initiation has been associated with subsequent development of inhibitors in previously untreated patients (PUPs) with severe hemophilia A in the frame of the SIPPET cohort (Cannavò A et al, Blood 2017).

Peyvandi: Octapharma: Other: Investigator; LFB, Kedrion, Novonordisk, Bayer, Roche, CSL Behring.: Consultancy, Honoraria, Research Funding. Mannucci:Novonordisk, Grifols, Kedrion, Bayer, Biotest, Baxalta: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Karimi:Octapharma: Other: Investigator. Young:Baxter, Grifols: Consultancy, Honoraria. Santagostino:Roche: Speakers Bureau; Bayer: Speakers Bureau; Baxter/Baxalta: Speakers Bureau; Octapharma: Speakers Bureau; Biotest: Speakers Bureau; Novo Nordisk: Speakers Bureau; Kedrion: Speakers Bureau; Biogen/Sobi: Speakers Bureau; CSL Behring: Speakers Bureau; Pfizer: Research Funding, Speakers Bureau. Mancuso:Baxter, Pfizer, CSL Behring, Baxter, Sobi/Biotest: Consultancy; Novo Nordisk, Bayer: Speakers Bureau. Mahlangu:Biogen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bayer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; CSL Behring: Research Funding; NovoNordisk: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Biotest: Honoraria, Membership on an entity's Board of Directors or advisory committees. Bonanad:Baxalta: Research Funding. Ewing:Baxter, Novo Nordisk, Grifols, Bayer, Kedrion: Honoraria. Owaidah:King abdulaziz city for science, Novo Nordisk, Bayer: Honoraria, Research Funding. Kobrinsky:Octapharma: Speakers Bureau; CSL Behring: Speakers Bureau; Sanofi: Speakers Bureau; Kedrion Biopharma: Membership on an entity's Board of Directors or advisory committees. Kavakli:Baxter: Other: advisory board member and received educational and investigational support; Bayer: Other: advisory board member and received educational and investigational support; Novo Nordisk: Other: advisory board member and received educational and investigational support; Pfizer: Other: advisory board member and received educational and investigational support; Bio Products Laboratory: Other: received educational and investigational support; CSL Behring: Other: received educational and investigational support; Octapharma: Other: received educational and investigational support. Manco-Johnson:Baxter, bayer, biogen, CSL Behring, NovoNordish: Honoraria. Neme:Novo Nordisk and Pfizer: Other: fees for speaking. Wicklund:NovoNordisk, Bayer, Baxter (now Baxalta), Biogen-Idec, CSL-Behring, National Hemophilia Foundation: Honoraria, Membership on an entity's Board of Directors or advisory committees. Zulfikar:Eczacýbaþý-Baxter, Pfizer, Novo Nordisk: Consultancy, Honoraria, Research Funding.

Gilbert score changes were small, and limited to the ankles, knees, and elbows. Group 2 had the highest overall bleeding score. Of the exploratory variables, Group 3 usually had numerically worse values than the other groups. For the HAL, Group 2 had a higher increase overall than Group 1. The STAI showed an increase in trait anxiety for Groups 1 and 2 during the study, and increase in state anxiety for group 1 but a decrease for Group 2. No other distinguishing findings emerged.Although the primary and main secondary efficacy variables showed clear benefits of continuing prophylaxis, the remaining secondary variables and the exploratory variables did not clearly distinguish between Groups 1 and 2, although most showed worse results for Group 3. For these variables the changes in Groups 1and 2 were usually small, occurred in a similar pattern in both groups, or showed inconsistent patterns. The changes in Group 3 suggest that quality of life decreases with length of time off prophylaxis. Small cell numbers, outliers, being in a clinical trial and questionnaire fatigue may be contributing factors.Manco-Johnson: Octapharma AG: Consultancy; Bayer: Research Funding. Ewing:CSL Behring: Consultancy, Honoraria, Research Funding, Travel funds; Baxter: Consultancy, Honoraria, Research Funding, Travel funds; Bayer: Consultancy, Honoraria, Research Funding, Travel funds; Biogen Idec: Consultancy, Honoraria, Research Funding, Travel funds; Grifols: Consultancy, Honoraria, Research Funding, Travel funds; Inspiration: Consultancy, Honoraria, Research Funding, Travel funds; NovoNordisk: Consultancy, Honoraria, Research Funding, Travel funds; Octapharma: Consultancy, Honoraria, Research Funding, Travel funds; Pfizer: Consultancy, Honoraria, Research Funding, Travel funds; Talecris: Consultancy, Honoraria, Research Funding, Travel funds. Humphries:Bayer: Employment.

Zieger: CSL Behring Hattersheim: Research Funding.

Abstract 707FN2This icon denotes a clinically relevant abstract

Abstract2288This icon denotes a clinically relevant abstract

Development of inhibitors to human FVIII (hFVIII) is a significant complication in the reversal and prevention of bleeding events in hemophilia A patients. Porcine FVIII (pFVIII) possesses low cross reactivity to anti-hFVIII antibodies. OBI-1, a recombinant B-domain deleted pFVIII, has recently been tested in a Phase II trial in patients with congenital hemophilia A and inhibitors experiencing a non-life/non-limb threatening bleed. In patients with a measurable anti-pFVIII antibody titer, dosing was initiated with a loading dose (LD) followed by up to 8 doses of 50 to 150 U/kg of OBI-1 administered at 6 hour intervals until the bleed was controlled. The PK profile of OBI-1 was assessed for the first OBI-1 infusion of each patient. FVIII levels were measured 30 minutes after each infusion. Inhibitor titers were evaluated for a minimum of 6 months after the first OBI-1 infusion. A total of 25 bleeding episodes in 9 patients were treated successfully with OBI-1. The median time from bleeding onset to treatment was 7 hours (range: 3 20 hr). OBI-1 showed a cumulative efficacy of 72% after 1 injection, 84% after 2 injections or less, 92% after 3 injections or less, and 100% after 8 or less injections. In over 40 infusions, OBI-1 was well tolerated and no drug related SAEs were observed. One case of pruritus rated as mild was easily controlled with diphenhydramine. FVIII levels measured 30 minutes after each OBI-1 infusion ranged from < 0.5% to 226%. They were generally lower with higher anti-pFVIII titers although all bleeds were successfully controlled. Follow up inhibitor titers are still being monitored and final results will be presented and discussed. Other investigative parameters, including vital signs and laboratory variables did not show treatment related abnormalities. OBI-1 can be given as a short infusion. It was effective in controlling all bleeds which occurred in this study and was well tolerated. The results suggest that a LD is not needed with OBI-1 treatment, and in some instances patients may have been over treated. Given the promising results in this study, additional studies are planned to optimize dose range for OBI-1 and to confirm the long term safety and efficacy of OBI-1 in the treatment of bleeds in a larger cohort of individuals with hemophilia A complicated by the presence of hFVIII inhibitors.

Development of inhibitors to human FVIII (hFVIII) is a significant complication in the reversal and prevention of bleeding events in hemophilia A patients. Porcine FVIII (pFVIII) possesses low cross reactivity to anti-hFVIII antibodies. OBI-1, a recombinant B-domain deleted pFVIII, has recently been tested in a Phase II trial in patients with congenital hemophilia A and inhibitors experiencing a non-life/non-limb threatening bleed. In patients with a measurable anti-pFVIII antibody titer, dosing was initiated with a loading dose (LD) followed by up to 8 doses of 50 to 150 U/kg of OBI-1 administered at 6 hour intervals until the bleed was controlled. The PK profile of OBI-1 was assessed for the first OBI-1 infusion of each patient. FVIII levels were measured 30 minutes after each infusion. Inhibitor titers were evaluated for a minimum of 6 months after the first OBI-1 infusion. A total of 25 bleeding episodes in 9 patients were treated successfully with OBI-1. The median time from bleeding onset to treatment was 7 hours (range: 3 20 hr). OBI-1 showed a cumulative efficacy of 72% after 1 injection, 84% after 2 injections or less, 92% after 3 injections or less, and 100% after 8 or less injections. In over 40 infusions, OBI-1 was well tolerated and no drug related SAEs were observed. One case of pruritus rated as mild was easily controlled with diphenhydramine. FVIII levels measured 30 minutes after each OBI-1 infusion ranged from < 0.5% to 226%. They were generally lower with higher anti-pFVIII titers although all bleeds were successfully controlled. Follow up inhibitor titers are still being monitored and final results will be presented and discussed. Other investigative parameters, including vital signs and laboratory variables did not show treatment related abnormalities. OBI-1 can be given as a short infusion. It was effective in controlling all bleeds which occurred in this study and was well tolerated. The results suggest that a LD is not needed with OBI-1 treatment, and in some instances patients may have been over treated. Given the promising results in this study, additional studies are planned to optimize dose range for OBI-1 and to confirm the long term safety and efficacy of OBI-1 in the treatment of bleeds in a larger cohort of individuals with hemophilia A complicated by the presence of hFVIII inhibitors.

In Reply.—We regret that the apprehensions of Drs Cattaneo, Gringeri, and Mannucci about induction of immune tolerance may deprive some of their patients with hemophilia A and inhibitors of the great benefit of inhibitor suppression, namely, the ability to be treated successfully for hemorrhages or surgery with the same doses of factor VIII as patients without inhibitors.Unfortunately, one patient, previously anti—human immunodeficiency virus negative while being treated with factor IX complex, seroconverted on a donor-screened, dry-heat-treated factor VIII concentrate, to our shock and dismay. Currently, more rigorously viral inactivated factor VIII concentrates are used in seronegative patients.We compared changes in T4 cell counts in protocol patients with that in other patients. Of 12 protocol patients, four (33%) had rising T4 counts (including patient 7, whose T4 count at the end of therapy was actually 0.8×109/L [854/mm3], not 0.5 × 109/L [594/mm3