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This prospective observational cohort study evaluates risk-stratified venous thromboembolism (VTE) screening in injured children. While the reported incidence of VTE is 6% to 10% among critically injured children, there is no standard for screening. Venous thromboembolism may have long-term sequelae in children, including postthrombotic syndrome.Patients admitted to a level 1 pediatric trauma center were risk stratified for VTE using a validated prediction algorithm. Children at high risk (risk scores ≥523; i.e., ≥1% risk) received screening duplex ultrasonography. Children at moderate risk (risk scores 410-522; i.e., 0.3-0.99% risk) were screened as a comparison/control.Three-hundred fifty-five children were consecutively risk stratified from October 2019 to May 2021. Forty-seven children received screening duplex ultrasounds: 21 from a high-risk cohort and 26 from a moderate-risk cohort. Four children were diagnosed with VTE in the high-risk cohort compared with seven in the moderate-risk cohort ( p = 0.53). Total incidence of VTE among screened children was 23.4% (11 of 47). Asymptomatic VTE accounted for 81.8% of all events (9 of 11). Fifty-four percent (6 of 11) of VTE were central venous catheter associated. Venous thromboembolism in surviving children resolved by 3 to 6 months with no symptoms of postthrombotic syndrome after 1 year. No cases of VTE were identified in unscreened children, yielding an institutional VTE incidence of 3.1% (11 of 355).Risk-stratified screening demonstrates a significant incidence of asymptomatic VTE in injured children. These results may guide reevaluation of prediction algorithms developed from symptomatic VTE risk and longitudinal study of the sequelae of asymptomatic VTE.Prognostic and Epidemiological; Level III.

Although multiple hormonal treatment strategies are effective in decreasing heavy menstrual bleeding (HMB) in adolescents, few studies have compared the relative effectiveness of hormone therapy on the basis of dose.Retrospective chart review SETTING: Urban tertiary care institution PARTICIPANTS: Adolescents aged 9-19 years with acute HMB and anemia in 2008-2018 INTERVENTIONS: We used billing codes to identify encounters for acute HMB with hemoglobin less than 12 mg/dl and reviewed initial treatment and time until resolution of acute HMB. We excluded patients who had previously used gonadal steroids or did not complete follow-up. We then compared patients who received combined oral ethinyl estradiol with progestin (EE/P) in standard dosing (EE ≤35 mcg/day) vs taper dosing (EE35mcg/day in any step-down regimen).Time until patient-reported resolution of acute HMB, measured in days from initial treatment RESULTS: Of 207 patients with vaginal bleeding and anemia, 90 met the criteria for review of therapy type and dose. Users of combined EE/P were hormone-naïve in 28/33 (84.8%) of those who initiated standard EE/P and 22/32 (68.8%) who initiated taper dosing. Bleeding duration was available for 15/28 (53.6%) and 18/22 (81.8%). Resolution of HMB occurred in 0-9 days with standard dosing (mean ±SD 2.1 ± 2.3 days) versus 1-15 days for taper dosing (4.9 ± 4.7; p = 0.04). Excluding six outliers of zero or more than 10 days, HMB ceased by 2.6 and 3 days (n = 12 and 15; p = 0.62).Currently recommended higher dose combined hormonal regimens do not appear to shorten the time to resolution of acute HMB in adolescents.

Increased awareness of von Willebrand Disease (VWD) has led to more frequent diagnostic laboratory testing, which insurers often dictate be performed at a facility with off-site laboratory processing, instead of a coagulation facility with onsite processing. Off-site processing is more prone to preanalytical variables causing falsely low levels of von Willebrand Factor (VWF) due to the additional transport required. Our aim was to determine the percentage of discordance between off-site and onsite specimen processing for VWD in this multicenter, retrospective study. We enrolled females aged 12 to 50 years who had off-site specimen processing for VWF assays, and repeat testing performed at a consulting institution with onsite coagulation phlebotomy and processing. A total of 263 females from 17 institutions were included in the analysis. There were 251 subjects with both off-site and onsite VWF antigen (VWF:Ag) processing with 96 (38IU/dL) being low off-site and 56 (22IU/dL) low onsite; 223 subjects had VWF ristocetin co-factor (VWF:RCo), 122 (55IU/dL) were low off-site and 71 (32IU/dL) were low onsite. Similarly, 229 subjects had a Factor VIII (FVIII) assay, and 67 (29IU/dL) were low off-site with less than half, 29 (13IU/dL) confirmed low with onsite processing. Higher proportions of patients demonstrated low VWF:Ag, VWF:RCo, and/or FVIII with off-site processing compared to onsite (McNemar's test P-value

Purpose Venous thromboembolism (VTE) in injured children is rare, but sequelae can be morbid and life-threatening. Recent trauma society guidelines suggesting that all children over 15 years old should receive thromboprophylaxis may result in overtreatment. We sought to evaluate the efficacy of a previously published VTE prediction algorithm and compare it to current recommendations. Methods Two institutional trauma registries were queried for all pediatric (age 5% risk), 322 (3.9%) as moderate risk (1–5% risk) and 7898 (95.5%) as low risk (

Study Objective Heavy menstrual bleeding (HMB) may be the sentinel event for identifying a patient with a bleeding disorder (BD). The levonorgestrel intrauterine system (LNG IUS) has been proposed as a treatment for HMB in adolescents with and without BDs; however, no standard protocols for LNG IUS insertion in these populations exist. Providers were surveyed regarding the use of the LNG IUS in adolescents with HMB, with and without BD. Design, Setting, Participants, Interventions, and Main Outcome Measures An institutional review board−approved survey assessing provider attitudes, LNG IUS insertion practices, and patient outcomes in adolescents with HMB, with and without BD, was electronically distributed to 3523 providers in the fields of hematology, adolescent medicine, and obstetrics and gynecology. Descriptive analysis was performed. Results A total of 312 respondents across all 3 specialties completed the survey. Nearly 100% of respondents considered the LNG IUS safe and effective treatment for adolescents with HMB, both with and without BD. Additionally, 66% of providers chose LNG IUS as the ideal treatment for HMB in patients with BD. Differences were noted in clinical setting for LNG IUS insertion, peri-procedural medication use, and post-procedure follow-up among specialties. Providers across all specialties reported low complication rates related to IUS insertion and use in both patient groups. Conclusion Providers considered the LNG IUS safe and effective treatment for HMB in adolescents with and without a diagnosed BD. Practice patterns regarding LNG IUS insertion in this population vary. Further research is necessary to explore IUS outcomes in adolescent patients with HMB, with and without BD, and to inform evidence-based protocols for LNG IUS insertion.

After vascular injury and exposure of subendothelial matrix proteins to the intravascular space, mediators of hemostasis are triggered and allow for clot formation and restoration of vascular integrity. Platelets are the mediators of primary hemostasis, creating a platelet plug and allowing for initial cessation of bleeding. Platelet disorders, qualitative and quantitative, may result in bleeding signs and symptoms, particularly mucocutaneous bleeding such as epistaxis, bruising, petechiae, and heavy menstrual bleeding. Increasing evidence suggests that platelets have functional capabilities beyond hemostasis, but this review focuses solely on platelet hemostatic properties. Herein, normal platelet function as well as the effects of abnormal function and thrombocytopenia are reviewed.

With licensure of extended half-life (EHL) factor products and the changing landscape of available hemophilia products, patients and providers have options for less treatment-intense prophylaxis. The impact of these products in clinical practice to date remains understudied. We aimed to quantify the use of EHL products in prophylaxis in the US using the ATHN-dataset, a database of 145 ATHN-affiliated hemophilia treatment centers (HTCs). Further, we aimed to quantify the impact of EHL on key hemophilia indicators including annualized bleed rates (ABRs), hemophilia joint health scores (HJHS) and quality of life (QOL) metrics. The use of EHL vs standard half-life (SHL) products in severe hemophilia was compared between June 2018 and March 2019 using the ATHN-dataset. A cohort of patients was also recruited from seven participating HTCs in order to compare ABR, HJHS and QOL between product classes. By March 2019 the number of individuals with severe Hemophilia A (SHA) receiving EHLs remained relatively stable (28.4%), whereas the number of prescribed non-factor products increased to 7.1%, with a diminishing majority of patients (64.0%) continuing to receive SHLs. The majority of patients with severe hemophilia B (SHB) received treatment with EHLs including 57.5% by March 2019. There was a trend toward lower ABR with use of EHLs in SHA and SHB, although this did not result in improved HJHS nor QOL. EHL use in the United States in severe hemophilia continues to increase, although at a slower rate in SHA with the availability of non-factor therapy. The impact of the EHL therapies in clinical practice should continue to be examined prospectively.

Introduction: The number of women and girls (WG) with bleeding disorders cared for at hemophilia treatment centers has increased dramatically over the last 30 years, owing to improved recognition of bleeding symptoms specific to WG. However, basic epidemiologic data of this population remain elusive. The ATHNdataset (American Thrombosis and Hemostasis Network) is a surveillance tool for people with bleeding disorders in the United States, providing demographic as well as bleeding symptom and treatment information. The aim of this study was to characterize the female cohort within the ATHNdataset. Methods: In this retrospective cohort study, the ATHNdataset was queried for demographic data, bleeding disorder diagnosis, bleeding symptoms, and treatment. Descriptive statistics were used. Results: As of December 31, 2017, 8,820 WG with a congenital bleeding disorder were enrolled in the ATHNdataset, comprising 24.5% of the entire ATHNdataset cohort (35,945). The most common reported diagnosis was von Willebrand disease (VWD), accounting for 62.9% of the population. Reproductive tract bleeding was reported in 15.8% of participants older than 15 years. Conclusions: The ATHNdataset describes the largest cohort of WG with bleeding disorders to date. VWD is the most common diagnosis in WG with bleeding disorders. Symptoms specific to WG, such as heavy menstrual bleeding, are underreported in this data set compared with other data sources. Ongoing efforts are needed to improve diagnosis, treatment, and surveillance of WG with bleeding disorders.

Immune thrombocytopenia (ITP) is an acquired autoimmune bleeding disorder which presents with isolated thrombocytopenia and risk of hemorrhage. While most children with ITP promptly recover with or without drug therapy, ITP is persistent or chronic in others. When needed, how to select second-line therapies is not clear. ICON1, conducted within the Pediatric ITP Consortium of North America (ICON), is a prospective, observational, longitudinal cohort study of 120 children from 21 centers starting second-line treatments for ITP which examined treatment decisions. Treating physicians reported reasons for selecting therapies, ranking the top three. In a propensity weighted model, the most important factors were patient/parental preference (53%) and treatment-related factors: side effect profile (58%), long-term toxicity (54%), ease of administration (46%), possibility of remission (45%), and perceived efficacy (30%). Physician, health system, and clinical factors rarely influenced decision-making. Patient/parent preferences were selected as reasons more often in chronic ITP (85.7%) than in newly diagnosed (0%) or persistent ITP (14.3%, P = .003). Splenectomy and rituximab were chosen for the possibility of inducing long-term remission (P < .001). Oral agents, such as eltrombopag and immunosuppressants, were chosen for ease of administration and expected adherence (P < .001). Physicians chose rituximab in patients with lower expected adherence (P = .017). Treatment choice showed some physician and treatment center bias. This study illustrates the complexity and many factors involved in decision-making in selecting second-line ITP treatments, given the absence of comparative trials. It highlights shared decision-making and the need for well-conducted, comparative effectiveness studies to allow for informed discussion between patients and clinicians.

BackgroundApproximately 40% of adolescent women experience heavy menstrual bleeding (HMB), and 10-62% of them have an underlying bleeding disorder (BD). Diagnosing a BD remains challenging because of limitations of available clinical platelet function assays. The aim of this study was to characterize platelet function in a population of adolescent women with HMB using small-volume whole-blood assays.MethodsAnticoagulated whole blood was used to assess platelet GPIIbIIIa activation, α-granule secretion, and aggregation in response to multiple agonists. Platelet adhesion on collagen or von Willebrand Factor (VWF) under static and shear flow was also assessed.ResultsFifteen participants with HMB were included in the study, of which eight were diagnosed with a clinically identifiable BD. Platelet activation was blunted in response to calcium ionophore in participants without a BD diagnosis compared with that in all other participants. Impaired GPIIbIIIa activation was observed in response to all GPCR agonists, except adenosine diphosphate (ADP), in participants with qualitative platelet disorders. Our assays detected platelet aggregation in the majority of participants with a BD in response to ADP, collagen-related peptide (CRP), thrombin receptor activator 6 (TRAP-6), or U46619. Platelet adhesion and aggregation on collagen and VWF was decreased for participants with VWD.ConclusionParticipants with and without BD exhibited aberrant platelet function in several assays in response to select agonists.

Background:Von Willebrand Disease (VWD) is the most common inherited bleeding disorder, occurring in ~0.1% of the population. VWD results from either a quantitative (Type 1 or 3) or qualitative (Type 2) defect in von Willebrand Factor (VWF), a multimeric plasma protein involved in platelet adhesion and aggregation at the vascular injury site. Accurate diagnosis of VWD is complex due to pre-analytical variables, a wide coefficient of variation in testing, and incomplete penetrance. Though individuals with mild VWD and bleeding symptoms are common, less is known regarding persons with VWD and a clinically severe bleeding phenotype. Aims:To characterize the bleeding phenotype and safety of treatment regimens in participants with clinically severe VWD in the United States (US). Study Design and Methods:ATHN 9 is sponsored by the American Thrombosis and Hemostasis Network (ATHN) and is being conducted at 25 ATHN-affiliated sites across the US. Participants are identified by the site investigators with a projected goal to enroll 130 individuals. Patients with severe VWD defined as type 3 VWD, or a VWF:RCo, VWF:GPIbM or VWF:Ag ≤ 30%, or persons with "clinically severe VWD" defined by VWF:RCo, VWF:GPIbM or VWF:Ag ≤ 40% and requiring recurrent use of factor concentrates and prior enrollment in the ATHNdataset national surveillance data collection project are included. Participants with platelet-type or acquired VWD are excluded. Laboratory assessments including a standardized diagnostic battery, VWF genetic analysis (Next-gen sequencing), and inhibitor testing, performed by a central laboratory. Bleeding tendency is assessed by International Society for Thrombosis and Haemostasis (ISTH) Bleeding Assessment Tool (BAT) (abnormal BS is ≥4 in adult males, ≥6 in adult females and ≥3 in children) and the Pictorial Bleeding Assessment Chart (PBAC; heavy menstrual blood loss ≥100) if applicable. Results:Initial data on 81 participants was analyzed. Given that the enrollment occurred during the pandemic, the completion of data varied as follows: Baseline Demographics Forms 81 completed, Baseline History Forms 73 completed, and VWD Diagnostic Testing Results Forms 38 completed. Most were adult (53%), female (58%), Caucasian (82%) and non-Hispanic (82%). Approximately half (38/81, 47%) have undergone central lab diagnostic testing (Table 1) while the remaining had previous diagnostic studies. About half of the patients had Type 1, a quarter have Type 3, and the remaining had Type 2 VWD or unknown. The majority of patients (91%) had VWF:GPIbM activity Discussion: Initial evaluation of 81 participants with clinically severe VWD were diagnostically determined to be type 1 VWD with a majority having a bleeding phenotype (mean (ISTH BAT 10) and HMB (mean PBAC 247). In contrast to patients with mild disease where antifibrinolytics and desmopressin are frequently used, factor replacement was the most common treatment modality. Future analysis will focus on response to factor replacement therapy, genotype-phenotype correlation and quality of life. Disclosures Weyand: Novo Nordisk: Research Funding; Genentech: Consultancy; Sanofi: Consultancy, Research Funding; Takeda: Consultancy. Friedman: Siemens: Consultancy; Bayer: Consultancy; Alexion: Speakers Bureau; Genentech: Consultancy; Instrumentation Laboratories: Consultancy; Sanofi: Consultancy. Haley: American Thrombosis and Hemostasis Network: Research Funding. He: ATHN: Ended employment in the past 24 months. Roberts: Takeda; Speakers Bureau: Novo Nordisk, Octapharma, Sanofi, Takeda.: Research Funding; Genentech, Novo Nordisk, Octapharma, Pfizer, Sanofi, Takeda, uniQure: Consultancy. Wynn: Sanofi: Research Funding; Takeda: Research Funding; Genentech: Research Funding. Sidonio: Sanofi, Takeda, Octapharma, Bayer, Biomain, Grifols, Kedrion, Genentech. Catalyst, Guardian Therapeutics, Novo Nordisk, Hema Biologics, Uniqure.: Consultancy, Honoraria. OffLabel Disclosure: Vonvendi (recombinant VWF) does not have a product indication for prophylaxis

The inherited bleeding disorder von Willebrand disease (VWD) is challenging to diagnose owing to disease heterogeneity, lack of a definitive laboratory test and variations in diagnostic criteria. We evaluated the impact of diagnosis and diagnostic delay on patient outcomes. The PharMetrics Plus Database was interrogated for medical claims for VWD (ICD-9 286.4) and bleeding events between 1 January 2006 and 30 June 2015. Longitudinal analysis was performed of patients newly diagnosed with VWD (≥9 months' continuous enrolment before first VWD claim) through 24 months following diagnosis. In total, 32 028 diagnosed, including 18 182 newly diagnosed, patients were identified. Most patients (72%) were female. Prediagnosis, bleeding symptoms were most commonly managed by a hospitalist/emergency room physician. Misrecognition of VWD was common, with 25% of patients visiting the same specialist type at least twice for an episodic bleed before diagnosis. Thirty-seven percentage of patients had no diagnostic laboratory test within 24 months of their initial diagnostic claim. Bleed claims reduced following diagnosis: 41% and 26% of female and male patients, respectively, had claims in the year prediagnosis, falling to 21% and 9% of patients at 1-2 years postdiagnosis. The proportion of patients with multiple bleed claims also decreased, from 17% to 6% (females) and 7% to 3% (males). Serially misrecognized patients continued to have more bleeding episodes than other patients, although bleed frequency was lower than before diagnosis. There is a need for improved patient management from bleeding presentation onward to reduce the time to VWD diagnosis and to enhance patient outcomes.

Red blood cell (RBC) destruction can be secondary to intrinsic disorders of the RBC or to extrinsic causes. In the congenital hemolytic anemias, intrinsic RBC enzyme, RBC membrane, and hemoglobin disorders result in hemolysis. The typical clinical presentation is a patient with pallor, anemia, jaundice, and often splenomegaly. The laboratory features include anemia, hyperbilirubinemia, and reticulocytosis. For some congenital hemolytic anemias, splenectomy is curative. However, in other diseases, avoidance of drugs and toxins is the best therapy. Supportive care with transfusions are also mainstays of therapy. Chronic hemolysis often results in the formation of gallstones, and cholecystectomy is often indicated.

Background: Von Willebrand Disease (VWD) is the most common inherited bleeding disorder, thought to occur in ~0.1% of the population. VWD results from a quantitative (Type 1 or 3) or qualitative (Type 2) defect in von Willebrand Factor (VWF), a multifunctional plasma protein involved in primary and secondary hemostasis. Diagnosis of VWD can be difficult due to pre-analytical variables, a wide coefficient of variation in testing, and incomplete penetrance. Treatment of VWD is aimed at replacement of the defective or missing protein through plasma derived or recombinant VWF, release of endogenous VWF through desmopressin (DDAVP) or clot stabilization with anti-fibrinolytic therapy. Though individuals with mild VWD and bleeding symptoms are common, less is known regarding individuals with VWD and a clinically severe bleeding phenotype. Aims: To characterize the bleeding phenotype and treatment regimens in patients with clinically severe VWD in the United States. Study Design and Methods: ATHN 9 is sponsored by the American Thrombosis and Hemostasis Network (ATHN) and is being conducted at ATHN-affiliated sites across the US. Participants were identified by the site investigators with the projected goal to enroll 130 individuals. Inclusion criteria were patients with severe VWD defined as type 3 VWD, or VWF:RCo, VWF:GPIbM or VWF:Ag≤ 30% or patients with "clinically severe VWD" defined by VWF:RCo, VWF:GPIbM or VWF:Ag ≤ 40% a with severe bleeding phenotype (need for recurrent use of factor concentrates) and prior enrollment in the ATHN dataset national surveillance data collection project. Patients with platelet-type or acquired VWD were excluded. Laboratory assessment including a standardized diagnostic battery, VWF genetic analysis, and inhibitor testing, was performed by a central laboratory. Bleeding was assessed using the International Society for Thrombosis and Haemostasis (ISTH) Bleeding Assessment Tool (BAT) (normal adult 0-4, normal score Results: Initial data on 35 participants was analyzed. Most were adult (69%), female (66%), Caucasian (86%) and non-Hispanic (89%). Just less than half (16/35, 45.7%) have completed diagnostic testing (Table 1). Half of the patients had Type 1, a quarter Type 3, and the remaining had Type 2 or unknown. The majority of patients (69%) had VWF GPIbM activity 150 is abnormal). The majority (3/4) of participants filling out the PBAC received VWF concentrate prophylaxis for HMB. The majority (23 participants, 66%) utilized factor concentrates for prophylaxis or on-demand treatment; six patients (17%) were on continuous prophylaxis, while 12 (34%) were on event-based or HMB prophylaxis while the remainder received episodic treatment. Participants most commonly used plasma derived VWF concentrate (93.9%) with the remainder using recombinant VWF. Discussion: Initial evaluation of 35 participants with clinically severe VWD demonstrated a predominance of mucosal bleeding with a minority of participants endorsing joint bleeds at enrollment. Despite abnormal ISTH BAT scores in all participants, PBAC scores were within normal range, likely reflecting appropriate management of HMB with most participants receiving VWF concentrate for HMB prophylaxis. In contrast to patients with mild disease where antifibrinolytics and desmopressin are frequently used, factor replacement was the most common treatment modality. Future analysis will focus on laboratory evaluation, bleeding phenotype, response to factor replacement therapy and quality of life. Disclosures Weyand: Shire: Membership on an entity's Board of Directors or advisory committees; Kedrion: Membership on an entity's Board of Directors or advisory committees; Aptevo: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees. Friedman:Alexion: Speakers Bureau; Bayer: Consultancy; Instrumentation Laboratories: Consultancy; Alexion: Consultancy. Haley:ATHN: Research Funding. Roberts:Sanofi: Consultancy, Speakers Bureau; Novo Nordisk: Consultancy, Speakers Bureau; Pfizer: Consultancy; Takeda: Consultancy, Research Funding, Speakers Bureau; uniQure: Consultancy; Octapharma: Consultancy, Speakers Bureau. Sidonio:Genentech: Membership on an entity's Board of Directors or advisory committees; Sanofi/Bioverativ: Membership on an entity's Board of Directors or advisory committees; Octapharma: Membership on an entity's Board of Directors or advisory committees; Bayer: Membership on an entity's Board of Directors or advisory committees; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees; Uniqure: Membership on an entity's Board of Directors or advisory committees; Biomarin: Membership on an entity's Board of Directors or advisory committees; Catalyst Sciences: Membership on an entity's Board of Directors or advisory committees; Emergent Solutions: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Kedrion: Membership on an entity's Board of Directors or advisory committees; Takeda: Research Funding; Genentech: Membership on an entity's Board of Directors or advisory committees; Octapharma: Research Funding; Grifols: Research Funding; Grifols: Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: VWF concentrates used for heavy menstrual bleeding

Despite the transient hyporeactivity of neonatal platelets, full-term neonates do not display a bleeding tendency, suggesting potential compensatory mechanisms which allow for balanced and efficient neonatal hemostasis. This study aimed to utilize small-volume, whole blood platelet functional assays to assess the neonatal platelet response downstream of the hemostatic platelet agonists thrombin and adenosine diphosphate (ADP). Thrombin activates platelets via the protease-activated receptors (PARs) 1 and 4, whereas ADP signals via the receptors P2Y1 and P2Y12 as a positive feedback mediator of platelet activation. We observed that neonatal and cord blood-derived platelets exhibited diminished PAR1-mediated granule secretion and integrin activation relative to adult platelets, correlating to reduced PAR1 expression by neonatal platelets. PAR4-mediated granule secretion was blunted in neonatal platelets, correlating to lower PAR4 expression as compared to adult platelets, while PAR4 mediated GPIIb/IIIa activation was similar between neonatal and adult platelets. Under high shear stress, cord blood-derived platelets yielded similar thrombin generation rates but reduced phosphatidylserine expression as compared to adult platelets. Interestingly, we observed enhanced P2Y1/P2Y12-mediated dense granule trafficking in neonatal platelets relative to adults, although P2Y1/P2Y12 expression in neonatal, cord, and adult platelets were similar, suggesting that neonatal platelets may employ an ADP-mediated positive feedback loop as a potential compensatory mechanism for neonatal platelet hyporeactivity.

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.

Essentials Assays are needed to aid in the diagnosis of platelet dysfunction in the neonatal population. We developed small-volume assays to assess neonatal platelet activation and aggregation. Compared to adult platelets, neonatal platelet activation and secretion was reduced. The extent of neonatal and adult platelet adhesion and aggregate formation were similar. SummaryBackground Acquired and inherited bleeding disorders may present in the neonatal period with devastating lifelong effects. Diagnosing bleeding disorders in the neonatal population could aid in preventing and treating the associated complications. However, currently available platelet function testing is limited in neonates, owing to difficulties in obtaining an adequate blood volume, a lack of normal reference ranges, and an incomplete understanding of the neonatal platelet functional phenotype. Objective To develop small-volume, whole blood platelet function assays in order to quantify and compare neonatal and adult platelet function. Methods and Results Peripheral blood was obtained from healthy, full-term neonates at 24 h of life. Platelet activation, secretion and aggregation were measured via flow cytometry. Platelet adhesion and aggregation were assessed under static and flow conditions. As compared with adult platelets, peripheral neonatal platelet P-selectin expression and integrin glycoprotein IIbIIIa activation were significantly reduced in response to the G-protein-coupled receptor (GPCR) agonists thrombin receptor activator peptide-6 (TRAP-6), ADP, and U46619, and the immunoreceptor tyrosine-based activation motif (ITAM) signaling pathway agonists collagen-related peptide (CRP) and rhodocytin. Neonatal platelet aggregation was markedly reduced in response to TRAP-6, ADP, U46619, CRP and rhodocytin as compared with adult platelets. The extents of neonatal and adult platelet adhesion and aggregate formation under static and shear conditions on collagen and von Willebrand factor were similar. Conclusions As compared with adult platelets, we found that neonatal platelet activation and secretion were blunted in response to GPCR or ITAM agonists, whereas the extent of neonatal platelet adhesion and aggregate formation was similar to that of adult platelets.

Immune thrombocytopenia (ITP) is a heterogeneous disease characterized by immune-mediated thrombocytopenia and associated with variable mucocutaneous bleeding. Historically, symptoms associated with ITP have been described for years. However, until the platelet was defined in the 1800s, the link to thrombocytopenia was unknown. From that point forward, the etiology of thrombocytopenia was debated and attributed at various times in history to increased platelet destruction and/or to decreased platelet production. The diagnosis is one of exclusion, and inherited and acquired causes of thrombocytopenia should be included in the differential diagnosis. In this chapter, the history of ITP, the terminology used in ITP, and the clinical presentation with differential diagnosis will be discussed.

The human hemostatic system is developmentally regulated, resulting in qualitative and quantitative differences in the mediators of primary and secondary hemostasis as well as fibrinolysis in neonates and infants. Although gestational and age related differences in coagulation factor levels occur, the existence of a unique neonatal platelet phenotype remains controversial. Complicated by difficulties in obtaining adequate neonatal blood volumes with which to perform functional assays, ambiguity surrounds the characterization of neonatal platelets. Thus, much of the current knowledge of neonatal platelet function has been based on studies from cord blood samples. Studies suggest that cord blood-derived platelets, as a surrogate for neonatal platelets, are hypo-functional when compared to adult platelets. This relative platelet dysfunction combined with a propensity toward thrombocytopenia in the Neonatal Intensive Care Unit population, creates a clinical conundrum regarding the appropriate administration of platelet transfusions. This review provides an appraisal of the distinct functional phenotype of neonatal platelets. Neonatal platelet transfusion practices and the impact of the relatively hypo-functional neonatal platelet on those practices will be considered.

Introduction Because of an increased awareness by the medical community of von Willebrand Disease (VWD) in females with heavy menstrual bleeding (HMB), diagnostic laboratory testing is often sent by primary care clinicians and obstetricians/gynecologists. Furthermore, insurers often necessitate testing be performed at an outside laboratory, instead of a hospital or academic based on-site coagulation laboratory. Falsely low von Willebrand factor (VWF) levels can occur due to pre-analytical variables, such as delayed processing and mishandling of VWF specimens. This study is the first multi-institutional analysis evaluating VWF testing to determine the percentage of post-menarchal females with discordant testing results when comparing off-site to on-site coagulation laboratories. Methods This retrospective, multi-center study compared VWF antigen, VWF activity/ristocetin cofactor (RCo) and factor VIII (FVIII) assays performed at off-site compared to on-site laboratories at 17 U.S. institutions. Data were collected in females aged 12 to 50 years who had VWF testing performed by their referring physician at off-site labs and then repeated under the guidance of a hematologist at their on-site lab. Data regarding clinical bleeding symptoms, final diagnosis and coagulation testing were also collected. The hematologist determined the final diagnosis. An off-site lab was defined as a clinic, community hospital or private facility where the phlebotomy and lab processing was not performed at the same center. Low VWF was defined as a VWF:RCo or VWF:Ag of 30-50% while type 1 VWD was defined as VWF:Ag or VWF:RCo Results A total of 264 subjects were included in the analysis and were evaluated for VWD between July 2013 and October 2017. Median age at first consultation visit was 15 years (range 12-50). The majority, 217 (83%), had heavy menstrual bleeding followed by easy bruising (n=96; 37%) and epistaxis (n=80; 30%). Testing was conducted while on hormonal contraception in 99 (38%) subjects at the initial consultation. Seventy-three subjects had normal or elevated VWD testing prior to hematology consultation. There were 251 (95%) subjects who had VWF antigen testing, and 96 (38%) had low VWF antigen ( Less than 40% (n=100) of subjects were given a final diagnosis of VWD (type 1, 2 or 3), and 7% were diagnosed with low VWF. Approximately 40% of the patients had a normal evaluation for disorders of hemostasis. Conclusions This study represents the largest multicenter evaluation comparing off-site to on-site laboratory testing of VWF assays in post-menarchal women. From the evaluable subjects, one-third to half of the VWF assays normalized when drawn and processed at a hospital or academic center coagulation lab. While a proportion of these patients with initially low levels may have had a "stress" induced response normalizing their levels at the time of on-site retesting, it appears the main discordance between assay results is most likely secondary to delayed processing of the specimen. This can lead to decay of factor activity if the plasma is not promptly separated and frozen prior to transport to the reference laboratory. Furthermore, transport could also affect sample integrity. These pre-analytical laboratory variables can lead to false positive results for VWD, leading to potential inappropriate interventions or inadequate therapy, in addition to added health care costs. These results highlight the need for VWD testing to be both drawn and processed on-site at a coagulation laboratory under the guidance of a hematologist. Since this may not always be practical in large geographic areas, further work in reducing the delay in processing is in order. Acknowledgements: This is a study was conducted by members of the Foundation for Women and Girls with Blood Disorders, supported by a grant from CSL Behring. Disclosures Jaffray: CSL Behring: Research Funding. Sidonio:Kedrion: Research Funding; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees; Bioverativ: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda-Shire: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genetech: Membership on an entity's Board of Directors or advisory committees, Research Funding; Uniqure: Membership on an entity's Board of Directors or advisory committees; Biomarin: Membership on an entity's Board of Directors or advisory committees; Grifols: Membership on an entity's Board of Directors or advisory committees, Research Funding; Octapharma: Membership on an entity's Board of Directors or advisory committees, Research Funding. Staber:Genentech: Honoraria; Spark: Honoraria; Novo Nordisk: Honoraria; UniQure: Honoraria; Bayer: Honoraria. O'Brien:Pfizer: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding.

Objective— Rho GTPase proteins play a central role in regulating the dynamics of the platelet actin cytoskeleton. Yet, little is known regarding how Rho GTPase activation coordinates platelet activation and function. In this study, we aimed to characterize the role of the Rho GTPase effector, p21 activated kinase (PAK), in platelet activation, lamellipodia formation, and aggregate formation under shear. Approach and Results— Stimulation of platelets with the glycoprotein receptor VI agonist, collagen-related peptide, rapidly activated PAK in a time course preceding phosphorylation of PAK substrates, LIM domain kinase LIMK1 and the MAPK/ERK kinase MEK, and the subsequent activation of MAPKs and Akt. Pharmacological inhibitors of PAK blocked signaling events downstream of PAK and prevented platelet secretion as well as platelet aggregation in response to collagen-related peptide. PAK inhibitors also prevented PAK activation and platelet spreading on collagen surfaces. PAK was also required for the formation of platelet aggregates and to maintain aggregate stability under physiological shear flow conditions. Conclusions— These results suggest that PAK serves as an orchestrator of platelet functional responses after activation downstream of the platelet collagen receptor, glycoprotein receptor VI.

Background : The hemophilia treatment landscape has evolved substantially in the last several years with the approval of extended half-life (EHL) products which reduce the burden of prophylaxis. Data reported from the American Thrombosis and Hemostasis Network (ATHN) as of June 2017 indicate that 21% of patients with moderate or severe hemophilia A, and 42% of patients with moderate or severe hemophilia B, receive prophylaxis utilizing an EHL. As new treatments become available and are adopted into practice, it is important to recognize the need for evaluation of efficacy, safety, and economic impact of their use outside of the clinical trial setting. We aimed to characterize the real world impact of EHL products by collecting detailed information on bleeding rates, joint health and quality of life amongst patients cared for at ATHN-affiliated Hemophilia Treatment Centers. We hypothesized that use of EHL products were utilized in at least 30% of patients and would lead to decreased ABRs and improved joint health. To date 67 of a planned 135 subjects have been enrolled, constituting this interim analysis. Methods:Subjects were recruited from seven U.S. Hemophilia Treatment Centers. Subjects with severe hemophilia A or B ≤ 30 years of age on prophylaxis or demand therapy were eligible for enrollment. Subjects excluded from study were those with a recent joint bleed (within the last 2 weeks) or those unwilling to complete all elements of the study. Data were collected during a one-time encounter concurrent with an appointment for clinical evaluation, including demographic information, treatment regimen, product type, frequency, location and severity of all bleeds, Hemophilia Joint Health Scores (HJHS), and Quality of life (QoL). Bleeding rates in subjects receiving prophylaxis were compared with those receiving on demand therapy by type treatment, EHL vs standard half-life (SHL), and by hemophilia type. Severity of bleeding events (mild, moderate, or severe) and HJHS were compared by prophylaxis groups. Results: A total of 67 patients were enrolled and eligible for analysis. This included 58 subjects with severe hemophilia A, and 9 subjects with severe hemophilia B. The mean age of the cohort was 15 years (median 12 years, IQR 8 - 21 years). For these patients whose race information was known, 89.1% were Caucasian, 3.3% African-American, 3.3% Asian, and 4.7% were of mixed or 'other' race. Eleven out of 61 (18.0%) subjects with known ethnicity were Hispanic. Among 59 patients whose treatment type were available, the majority were on prophylaxis (n=53; 89.8%) as compared to on demand therapy (n=6; 10.2%). The average annualized bleeding rate (ABR) was 2.8 amongst all individuals. As expected, the ABR was substantially lower in those receiving prophylaxis (ABR=1.0) as compared to on demand therapy (ABR=18.6) (p For patients with severe hemophilia A, the ABR was lower in those individuals receiving EHL (ABR= 0.5) versus SHL (ABR= 1.5), although this did not reach statistical significance (p=0.136). All subjects with severe hemophilia B enrolled to date receive EHL products (n=9) therefore no comparison of ABR could be made between EHL and SHL products; the ABR in this group was 0.9. In patients with severe hemophilia A, there was a higher HJHS for those receiving EHL (mean HJHS= 7.0) versus those receiving SHL (mean HJHS = 2.1) (p=0.053). For patients with severe hemophilia B, all of whom received EHL, the mean HJHS was lower than in the hemophilia A cohort (mean HJHS=1.2). Conclusions: We report real-world bleeding events and joint health in patients with severe hemophilia A and B utilizing EHL and SHL products across a wide U.S. geographic distribution. As anticipated, there is substantial bleed reduction with prophylaxis versus on demand therapy. In our severe hemophilia A cohort, the ABR for patients receiving EHL products was similar to ABRs reported in clinical trials, suggesting clinical trial data may be reflective of real world use. Patients with severe hemophilia A receiving EHL for prophylaxis had a lower ABR than those receiving SHL, although the early impact is not reflected in the HJHS score. Longer follow-up will be necessary to determine the impact of EHL on HJHS. Disclosures Malec: Bioverativ: Research Funding; Bayer: Consultancy; Bioverativ: Consultancy; Shire: Consultancy. Jaffray:Octapharma: Consultancy; Bayer: Consultancy; CSL Behring: Consultancy, Research Funding. Kouides:UniQure: Other: DSMB; Octapharma: Research Funding. Sidonio:Octapharma: Other: Advisory Board; Genentech: Other: Advisory Board, Research Funding; CSL Behring: Other: Advisory Board; Shire: Other: Advisory Board, Research Funding; Novo Nordisk: Other: Advisory Board; Kedrion: Research Funding; Biomarin: Other: Advisory Board; Grifols: Other: Advisory Board, Research Funding; Bioverativ: Other: Advisory Board, Research Funding; Uniqure: Other: Advisory Board. Abshire:CSL: Consultancy; Shire: Consultancy; Novo Nordisk: Other: DSMB. White:Asklepios: Other: Scientific Advisory Board; Novo Nordisk: Consultancy; Shire: Other: Physician Leadership Group; Bayer: Other: GRAC; Bioverativ: Other: DSMB; Biomarin: Other: DSMB; Invitrox: Other: Scientific Advisory Board; Pfizer: Equity Ownership. Ragni:CSL Behring: Research Funding; Biomarin: Membership on an entity's Board of Directors or advisory committees, Research Funding; SPARK: Consultancy, Research Funding; Shire: Research Funding; Bioverativ: Consultancy, Research Funding; Alnylam: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novo Nordisk: Research Funding; Sangamo: Research Funding; MOGAM: Membership on an entity's Board of Directors or advisory committees.

Background: The impact of second line therapies on health related quality of life (HRQoL) and fatigue in pediatric patients with ITP is not well studied. Objective: To describe the impact of second line therapies on HRQoL and fatigue in North American pediatric patients with ITP. Methods: A longitudinal observational cohort of 120 children with ITP starting second line treatments was enrolled from 2013-2015 at 21 ICON centers. Enrollment requirements included age 1-17y and starting a second line treatment (not IVIG, corticosteroids or anti-D immunoglobulin) as monotherapy. HRQoL (Kids ITP Tool - KIT) and fatigue (Hockenberry Fatigue Scale - FS) surveys were completed prior to starting treatment (baseline) and 1 and 12 months after starting treatment by patient/caregiver. KIT is scored from 0 (worst) to 100 (best), and the FS scores were re-scaled so that 0 is no fatigue and 100 is highest fatigue. At the same time points as the patient/caregiver surveys, physicians assessed the perceived effect of treatment on patient HRQoL using a 7-point scale. ANOVA was used to compare the baseline means of the treatment groups. This study specifically compared change from baseline to 1 month in the KIT and FS using paired t-tests within each treatment group. The 12 month timepoint was not used in the paired analysis of individual treatments due to attrition between 1 and 12 months. Results: The median age at enrollment was 11.3 y (1.2-17.8), and 16% (19/120) had newly diagnosed ITP, 31% (37/120) had persistent ITP, and 53% (64/120) had chronic ITP. The median number of prior treatments was 3 (range: 1-9). Fifty-eight (48%) patients had received at least one prior second line treatment. Treatments selected for second line treatment included: rituximab (n=43), romiplostim (n=31), eltrombopag (n=20), oral immunosuppressants (n=19), splenectomy (n=4), and dapsone (n=3). The child and parent proxy KIT scores significantly improved on rituximab (p As previously described, at enrollment, physicians reported that ITP had impacted the patients' HRQoL severely in 15%, significantly in 45%, moderately in 38%, and almost not at all in 3%. Physicians reported that HRQoL improved in 68% (range: 64-75%) of patients while on treatment from baseline to 1 month with no significant difference by treatment group (p=0.46). The physician's assessment of the patient's baseline HRQoL significantly correlated with the child and parent proxy KIT report (p At enrollment, the median FS-Child score (n=54) was 18.5 (range 0-85), the median FS-Adolescent score (n=42) was 20.2 (0-73), and the median FS-Parent (n= 100) score was 35 (7-81). One month FS-Child improved for those who were treated with rituximab (p=0.03); there was no significant change in fatigue on the other treatments. One month FS-Parent significantly improved for those treated with rituximab (p=0.015) and eltrombopag (p=0.009). Conclusions: In this pediatric cohort, all second line treatments appear to significantly improve HRQoL in ITP. Rituximab had the greatest impact in decreasing fatigue at one month. Physician assessment of patient HRQoL did not correlate well with patient assessment after treatment was started, suggesting there may be challenges in ascertaining the effect of treatment on HRQoL. Future analysis of ICON1 will consider the impact of treatment on HRQoL and fatigue while also accounting for the treatment effect on bleeding and platelet count. Disclosures Grace: Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Klaassen: Amgen: Consultancy; Hoffman-La Roche LTD: Consultancy; Octapharma: Honoraria; Baxalta: Honoraria; Biogen Canada LTD: Consultancy; Agios Pharmaceuticals: Consultancy. Despotovic: Sanofi: Consultancy; Schell Cooley LLP: Other: Expert witness. Bussel: Protalex: Membership on an entity's Board of Directors or advisory committees, Research Funding; Momenta: Membership on an entity's Board of Directors or advisory committees; Rigel: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees, Research Funding. Rothman: Pfizer: Consultancy; Agios Pharmaceuticals: Honoraria. Haley: Genentech: Honoraria; Baxalta: Honoraria; CSL Behring: Honoraria. Neufeld: Octapharma: Consultancy, Honoraria; Genentech: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees. Lambert: Educational Concepts in Medicine: Honoraria; Novartis: Honoraria; AstraZeneca: Research Funding.

Background: The indications for treating children with immune thrombocytopenia (ITP) remain controversial. A valid and reliable bleeding assessment tool could assist in objectively quantifying bleeding and influence treatment decisions. Both the ITP Bleeding Score (IBLS) and the ITP-Bleeding Assessment Tool (BAT) have been developed to assess bleeding severity in ITP. The IBLS scores bleeding severity using an 11-item tool with grading from 0 to 2 and the 18-item BAT grades from 0 to 3 or 4. The BAT includes some types of bleeding not represented on the IBLS, such has intramuscular hematomas. To date, no data describe how these two measures compare when measuring bleeding associated with ITP. Objective: To describe and compare bleeding as assessed by both the IBLS and BAT and to correlate bleeding severity with platelet counts in a cohort of children with ITP. Methods: A longitudinal observational cohort of children ages >1 and < 18 years with ITP, were enrolled from 2013-2015 in the Pediatric ITP Consortium of North America ICON1 trial. All children were enrolled prior to starting a new second line monotherapy (not IVIG, steroids or anti-D). At enrollment, bleeding was assessed using the IBLS in all children. A subset of children also underwent a BAT assessment. Grades of bleeding were described and compared between tools and agreement in grading was assessed. Severity was correlated with platelet count using Spearman's correlation calculation. Results: 118 children were enrolled from 21 ICON centers. 54% had chronic ITP and the median age was 11.4y (range 1.2-17.8). The mean platelet count was 28 x 109/l (SD 57) and 88% had a baseline platelet count of Conclusion: The IBLS and BAT were similarly effective at identifying bleeding symptoms, although neither tool showed strong correlation with the platelet count. There were moderate correlations noted between skin bleeding scores and platelet counts for both tools. A major limitation of this comparison is the different definitions of bleeding severity between the two measures. For sites where the items were more detailed, agreement declined (i.e. adding specificity reduced generalizability). While no patients in our cohort exhibited significant grade 3 or 4 bleeding outside of skin findings, we conclude that in the setting of clinical trials, the ability to capture very severe bleeding might be an important distinction that supports using the more complicated BAT, but for clinical practice, a simplified assessment such as the IBLS may suffice. Disclosures Grace: Agios Pharmaceuticals: Other: Scientific Advisor, Research Funding. Neufeld:Novartis: Consultancy. Bussel:Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; UpToDate: Patents & Royalties; Protalex: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genzyme: Research Funding; Ligand: Membership on an entity's Board of Directors or advisory committees, Research Funding; Symphogen: Membership on an entity's Board of Directors or advisory committees; Rigel Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Shionogi: Membership on an entity's Board of Directors or advisory committees; Sysmex: Research Funding; Momenta Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Immunomedics: Research Funding; Eisai: Membership on an entity's Board of Directors or advisory committees, Research Funding; Boehringer Ingelheim: Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Cangene: Research Funding; Prophylix Pharma: Membership on an entity's Board of Directors or advisory committees, Research Funding; GSK: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Physicians Education Resource: Speakers Bureau; BiologicTx: Research Funding. Haley:CSL Behring: Honoraria; Baxalta: Membership on an entity's Board of Directors or advisory committees. Thompson:Celgene: Research Funding; ApoPharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Mast: Research Funding; Amgen: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Research Funding; Amgen: Research Funding; Baxalta (now part of Shire): Research Funding; bluebird bio: Consultancy, Research Funding; Baxalta (now part of Shire): Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; bluebird bio: Consultancy, Research Funding; Mast: Research Funding; ApoPharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Eli Lily: Research Funding; Eli Lily: Research Funding.

Introduction: Nearly 40% of adolescent women experience heavy menstrual bleeding (HMB), and identifiable bleeding disorders are diagnosed in only 20-60% of these patients. We suspect that qualitative platelet disorders contribute to HMB, but are under-diagnosed. A pilot study was conducted to evaluate platelet function in adolescent women with HMB employing four novel, small-volume, whole blood platelet function assays. In addition, primary and secondary hemostasis, bleeding phenotype, and quality of life were assessed. Methods: Patients referred to the Young Women's Hematology Clinic at Oregon Health & Science University for evaluation of HMB were offered participation in the study. Participants underwent standard review of their medical and family history and physical exam. Standard lab evaluation included CBC, PT, PTT, fibrinogen, thrombin time, Von Willebrand Panel, PFA-100, and iron studies with platelet aggregation or phenotyping performed if clinically indicated. Using less than 0.5 mL of whole blood, platelet function was assessed with four novel platelet function assays: assessment of platelet activation, secretion, and aggregation was assessed by flow cytometry analysis, while platelet adhesion and aggregation was assessed under shear in a capillary tube. Quality of life (QOL) was assessed using the PedsQL tool. Bleeding phenotype was assessed with the ISTH Bleeding Assessment Tool (ISTH BAT). Menorrhagia was assessed with the Pictorial Bleeding Assessment Chart (PBAC), the Philipp Tool and the clinical history. Results: Nine participants have enrolled on study to date, with 2 completing the 3-month visit. The median age of the cohort was 16 years (14-18 years). Eight out of nine categorized their period as heavy, 6 also had epistaxis, and 7 reported excessive bruising. The median ISTH BAT score was 4 (3-7). Of the 7 patients who had a Philipp Score obtained, 5 were positive. Median PBAC score was 161 (64-196). Median ferritin was 13 ng/mL (4-65 ng/mL). Median QOL psychosocial score was 70 (68.36-88.25), comparable to that of pediatric patients with cancer. Of the 9 participants, 6 had platelet aggregation and phenotyping. Four participants did not receive a bleeding disorder diagnosis, 1 was diagnosed with Type 1 VWD, 1 was diagnosed with bleeding disorder, NOS, and 1 was diagnosed with Ehlers Danlos Syndrome. Two participants were diagnosed with a qualitative platelet disorder (QPD): one based on platelet aggregation and one based on thromboelastography. The four novel platelet function assays confirmed platelet function abnormalities in the participants diagnosed with QPD's (Figure 1&2). Impaired platelet response to agonist stimulation was also observed in participants with non-platelet disorder bleeding disorder diagnoses and in participants without a bleeding disorder diagnosis. Conclusions: In this pilot study, the etiology of HMB in adolescent women was evaluated with four novel platelet assays in addition to standard assays of hemostasis. A bleeding disorder diagnosis was not made with standard evaluations in 4 out of 9 participants. The novel assays detected platelet abnormalities not observed using currently available clinical labs, and confirmed the presence of abnormal platelet function in participants with abnormal platelet function testing. These assays require significantly less blood volume than currently available assays and expand investigation of platelet function to platelet adhesion and platelet interactions in whole and flowing blood. Further work is needed to determine the sensitivity and specificity of the novel assays in detecting platelet dysfunction. Continued investigation into the impact of HMB on the adolescent female population is needed. Disclosures Haley: CSL Behring: Honoraria; Baxalta: Membership on an entity's Board of Directors or advisory committees. Recht:Biogen: Membership on an entity's Board of Directors or advisory committees; CSL Behring: Membership on an entity's Board of Directors or advisory committees; Biogen: Research Funding; Genentech: Research Funding; Novo Nordisk: Research Funding; Baxalta: Research Funding; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees.

Background: Decision-making in selecting second-line therapies for pediatric patients with immune thrombocytopenia (ITP) has not been studied. Using data collected from physicians experienced in treating ITP, we developed a conceptual model of factors that informed treatment choice. This study was a component of ICON1, a prospective, observational, longitudinal cohort study of second line treatments for childhood ITP performed by the Pediatric ITP Consortium of North America (ICON). Methods: Physicians who enrolled patients in ICON1 were asked to rank the top three reasons they chose a specific treatment so as to weight each factor. Those choices that were ranked 1, 2, or 3 were weighted to develop a propensity scored decisional model. In other questions, physicians were asked about all factors that may have influenced decisions to begin a particular second line therapy and this data was then used to examine additional factors that influenced therapy choices and to compare between therapies. Results: ICON1 enrolled 118 patients; 101 had primary ITP and 53 were receiving their first second line therapy. The majority of physicians in the study saw eleven or more patients per year, and the time since completion of fellowship ranged from 1 to 44 years (mean 12.5 (SD 11)). The most important factors guiding treatment decisions in propensity weighted modeling were "patient preference factors": patient/parental preference (40%), and treatment-related factors: possibility of remission (38%), side effect profile (36%), efficacy (27%), long-term toxicity (33%), and ease of administration (30%). Physician factors, such as experience and adhering to published guidelines, rarely influenced decision-making with only 2% of physicians giving published guidelines as a reason for choice of therapy, and there being no difference in choice based on years since fellowship or experience in treating ITP patients. However, 28% of physicians stated their comfort level with a treatment strongly influenced their choice. Additionally, 38% of physicians did not endorse any patient clinical factors (e.g. frequency of bleeding, expected compliance, response to other therapies, age, comorbidities) as key in their decision-making. Health system factors, such as insurance approval or distance from the closest medical center, rarely influenced treatment choice. Treatments could be categorized into five groups: oral immunosuppressive agents, rituximab, romiplostim, eltrombopag or splenectomy. A significant determinant of choosing splenectomy or rituximab was the "possibility of long-term remission" (p Conclusions: This first analysis of physician decision making regarding second line therapies shows that patient preference and physician perception of treatment characteristics (efficacy, side effects, possibility of long term remission) are primary drivers of physician choice in contrast to guidelines, clinical characteristics and health system factors. Future comparative effectiveness studies are necessary to better inform patient and physician choice. Disclosures Lambert: Novartis: Consultancy. Grace:Agios Pharmaceuticals: Other: Scientific Advisor, Research Funding. Bussel:Cangene: Research Funding; GSK: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Ligand: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sysmex: Research Funding; Symphogen: Membership on an entity's Board of Directors or advisory committees; BiologicTx: Research Funding; Shionogi: Membership on an entity's Board of Directors or advisory committees; Physicians Education Resource: Speakers Bureau; Protalex: Membership on an entity's Board of Directors or advisory committees, Research Funding; Immunomedics: Research Funding; Rigel Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Boehringer Ingelheim: Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; UpToDate: Patents & Royalties; Momenta Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Prophylix Pharma: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genzyme: Research Funding; Eisai: Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Haley:Baxalta: Membership on an entity's Board of Directors or advisory committees; CSL Behring: Honoraria. Neufeld:Novartis: Consultancy.

¬Cancer induces a hypercoagulable state, and patients with cancer who suffer a thrombotic event have a worse prognosis than those who do not. Recurrent pathologic thrombi in patients with cancer are clinically managed with anticoagulant medications; however, anticoagulant prophylaxis is not routinely prescribed owing to a complex variety of patient and diagnosis related factors. Early identification of patients at risk for cancer-associated thrombosis would allow for personalization of anticoagulant prophylaxis and likely reduce morbidity and mortality for many cancers. The environment in which a thrombosis develops in a patient with cancer is complex and unique from patients without cancer, which creates therapeutic challenges but may also provide targets for the development of clinical assays in this context. Circulating tumor cells (CTCs) may play a role in the association between cancer and thrombosis. Cancer metastasis, the leading cause of cancer-related deaths, is facilitated by the hematogenous spread of CTCs, and CTCs accompany metastatic disease across all major types of carcinomas. The role of CTCs in the pathogenesis of thrombosis has not been studied due to the previous difficulty in identifying these rare cells, but the interaction between these circulating cells and the coagulation system is an area of study that demands attention. The development of CTC detection platforms presents a new tool by which to characterize the role for CTCs in cancer-related hypercoagulability. In addition, this area of study presents a new avenue for assessing the risk of cancer associated thrombosis and represents a potential tool for predicting which patients may benefit from anticoagulant prophylaxis. In this review, we will discuss the evidence in support of CTC induced hypercoagulability, and highlight areas where CTC-detection platforms may provide prognostic insight into the risk of developing thrombosis for patients with cancer.

Introduction: The laboratory work-up of von Willebrand Disease includes measurement of Von Willebrand Factor (VWF) antigen (VWF:Ag), VWF activity (ristocetin cofactor activity, VWF:RCo), and factor VIII Activity (FVIII), where VWF:Ag and VWF:RCo below 30-40% in the appropriate clinical setting are consistent with VWD. Accurate diagnosis of type 2 VWD, marked by a qualitative deficiency in the VWF protein, is imperative for appropriate therapeutic interventions. Exon 28 sequencing is frequently pursued to confirm the diagnosis of type 2 VWD. An exon 28 polymorphism, D1472H, results in impaired VWF binding to ristocetin, affecting the clinical assay of VWF activity as measured by ristocetin cofactor activity, but not resulting in impaired VWF function in vivo. This polymorphism is common in the healthy population and does not result in a hemorrhagic phenotype. We reviewed our institution’s experience with exon 28 sequencing with regard to the D1472H polymorphism, laboratory phenotype, and ultimate clinical diagnosis. Methods: Following IRB approval, patients who underwent exon 28 sequencing during evaluation for clinically significant bleeding between the years of 2003-2013 were identified. A retrospective chart review was conducted: patient demographics, VWF:RCo (lowest recorded), VWF:Ag (obtained on same day as the lowest VWF:RCo), and clinical diagnosis were collected. Descriptive statistics were employed to analyze the data. Results: Seventy-three patients underwent exon 28 sequencing during their work up for symptomatic bleeding between 2003-2013. The median age at testing was 7 years (10 months – 56 years), 41% were females. Of the 73 patients tested, D1472H polymorphism results for 65 patients were available for review. Fourteen patients (21.5%) were found to be heterozygous for the D1472H polymorphism. No patients were found to be homozygous. There was no difference between the mean VWF:RCo/VWF:Ag ratio for the D1472H heterozygous group (64% [47-81%]) and the group without the polymorphism (64% [48-80%]). VWF:RCo was lower in the heterozygotes with type 1 VWD (23.5% [14.5%-32.5%]) than in the group without the polymorphism (31% [18.5%-43.5]) (Table 1). In the group heterozygous for the D1472H polymorphism, 5/14 were diagnosed with type 1 VWD (Table 2). Two were diagnosed with type 2M VWD. One patient was diagnosed with type 1 VWD and mild hemophilia, 1 had type 1 VWD and Factor XI deficiency, 1 had type 2B VWD, 1 had chronic thrombocytopenia. Three patients did not have bleeding disorders. Conclusion: At our institution, heterozygosity for the exon 28 D1472H polymorphism was not associated with decreased VWF:RCo or VWF:RCo/VWF:Ag ratios as compared to patients without this polymorphism in all patients tested. For patients diagnosed with type 1 VWD, the VWF:RCo was lower in the group heterozygous for the D1472H mutation. These patients had sub-normal levels of VWF:Ag and VWF:RCo in the setting of clinically significant bleeding. Thus, the provisional diagnosis of VWD was appropriate despite the potential effect of the polymorphism on the VWF:RCo. These results are inconsistent with previously reported studies where presence of the D1472 polymorphism resulted in lower VWF:RCo/VWF:Ag ratios and inaccurate diagnosis of VWD. This study highlights the challenges associated with the laboratory diagnosis of VWD and the importance of continued research into the development of reliable VWD testing that more closely mimics the protein’s in vivoactivity. Abstract 2849. Table 1.VWF Assay Results for patients with and without the D1472 polymorphismD1472H+ all comersD1472H - all comersD1472H + no VWDD1472H + type 1 VWDD1472H - no VWDD1472H - type 1 VWDNumber of patients1451371420VWF Ag52%54%90%38%117%47%VWF:RCo37%37%72%23%100%31%VWF:RCo/VWF:Ag0.640.640.80.60.850.65Abstract 2849. Table 2.Patients with D1472H + and type 1 VWDPatient No.Age at testing (years)SexVWF:AgVWF:RCoVWF:RCo/VWF:AgDiagnosis118M47%27%0.57type 1 VWD23M23%14%0.61Type 1 VWD339F23%16%0.70type 1 VWD416F25%13%0.52type 1 VWD56M57%31%0.54type 1 VWD656M40%27%0.68type 1 VWD, factor XI deficiency74M53%37%0.70type 1 VWD, mild hem A Disclosures No relevant conflicts of interest to declare.

Drug-induced immune hemolytic anemia (DIIHA) is an uncommon side effect of pharmacologic intervention. A rare mediator of DIIHA, carboplatin is an agent used to treat many pediatric cancers. We describe here, the first case of fatal carboplatin induced DIIHA in a pediatric patient and a brief review of the literature. Our patient developed acute onset of multi-organ failure with evidence of complement activation, secondary to a drug induced red cell antibody. Early recognition of the systemic insult associated with carboplatin induced hemolytic anemia may allow for future affected patients to receive plasmapheresis, a potentially effective therapy.

Background The hemostatic system is developmentally regulated, resulting in qualitative and quantitative differences in the mediators of primary and secondary hemostasis as well as fibrinolysis. Age-dependent values of pro- and anti-coagulant proteins have been determined. However, the task of defining age-dependent normal values of neonatal platelet function has been met with challenges owing to difficulties in obtaining adequate blood volumes for functional assays and inconsistent results amongst varying testing methods. In order to overcome many of these challenges, cord blood is often used as a source of neonatal platelets. Platelet aggregometry comparing adult and cord blood derived platelets has demonstrated a near lack of platelet response to epinephrine, collagen, and thromboxane in cord blood samples. In contrast, other studies of platelet function, such as flow cytometry, have failed to demonstrate this phenotypic difference. Assays of primary hemostasis reveal that neonatal blood mediates primary hemostasis as effectively as adult blood. In order to overcome the challenges associated with studying neonatal platelets, we have developed a novel platelet function assay employing small volumes of blood obtained directly from the neonate in order to assess platelet adhesion, activation, and aggregation simultaneously. Methods Eight-well slide chambers were coated with either fibrillar collagen or fibrinogen and allowed to adsorb at room temperature for one hour. Blood was obtained from healthy adult controls via venipuncture and neonatal samples via heelstick into sodium citrate. The blood was separated into two 200 µl aliquots, and TRAP (Thrombin Receptor Activating Peptide: 30 mM) was added to one aliquot. 100 µl of plain whole blood was added to both a collagen and a fibrinogen coated well and 100 µ of whole blood plus TRAP was added to a fibrinogen coated well. The samples were then incubated at 37°C for 30 minutes. Non-adherent cells were washed three times with modified HEPES-Tyrode buffer. FITC-P-selectin was then added (10 µg/ml), and the samples were incubated at 37 oC for 10 minutes and subsequently washed. Samples were imaged with differential interference contrast (DIC) and fluorescence microscopy on a Zeiss Axiovert 200 M microscope. Results Platelet adhesion, activation, and aggregation were assessed for 3 neonatal samples and 3 adult control samples. Both adult and neonatal platelets adhered to fibrinogen and collagen equally. Exposure to collagen and fibrinogen (+/- TRAP) resulted in alpha granule release and P-selectin expression in both neonatal and adult platelets. In addition, both adult and neonatal platelets were observed to undergo the characteristic cytoskeletal changes that result in platelet spreading on fibrinogen (+/- TRAP) and collagen surfaces. Both neonatal and adult platelets were observed to form platelet aggregates on both surfaces under static conditions. (Figure 1) Conclusions We have successfully developed a novel platelet function assay using small volumes of whole blood to assess three key platelet functions: adhesion, activation, and aggregation. This is the first study to demonstrate that neonatal platelets spread on adhesive and extracellular matrix proteins and suggests that neonatal platelets contain the cytoskeletal machinery necessary to undergo this change in platelet formation. This assay fills a critical need in clinical pediatric hematology where efforts to diagnose and treat neonatal platelet dysfunction are often met with technical challenges related to conventional platelet function assays. Disclosures: No relevant conflicts of interest to declare.

Abstract 1060 Platelets serve as the primary mediators of hemostasis and thrombosis, circulating as surveyors for gaps in vascular integrity. As platelets encounter exposed extracellular matrix proteins, receptors on the platelet surface trigger intracellular signaling events that result in rapid platelet activation and a complex rearrangement of platelet morphology to form filopodia and lamellipodia. Rac1, a member of the Rho GTPase family, has emerged as a key regulator in platelet actin dynamics. However, the specific downstream events following Rac1 activation that mediate platelet actin cytoskeleton reorganization remain ill-defined. The Rho GTPase, Rac, supports the autocatalytic activation of the p21 activated kinases, or PAKs, to mediate actin reorganization processes in focal adhesion formation and cell migration. Upon activation by GTP-bound Rac, the PAKs phosphorylate a number of substrates to coordinate actin dynamics. Platelets express a number of PAK isoforms, and like Rac, PAK has been shown to be activated as platelets spread on collagen in a Src and PI3K dependent manner. Furthermore, the adaptor protein SLP-76 has been proposed to potentiate PAK activity downstream of Rac activation to mediate platelet lamellipodia formation. However, the specific roles of PAK in platelet function have yet to be characterized. Thus we set out to elucidate the role of PAK in platelet function and to define the connection between Rac activation, PAK, and platelet cytoskeletal reorganization. Our initial experiments with mass spectrometry revealed that following platelet activation, Rac1 associates with a set of PAK effectors, GIT1, GEFH1, LIMK1, and Merlin. We next demonstrated a co-localization of Rac1 and PAK with actin at the leading edge of spread platelets on fibrinogen. In addition, inhibition of PAK signaling by two different pharmacologic inhibitors blocked platelet focal adhesion and lamellopodia formation on both fibrinogen and collagen. Inhibition of PAK signaling abrogated intracellular calcium mobilization in platelets, prevented platelet aggregation to the GPVI-agonist, CRP, and destabilized platelet lamellipodia, resulting in the retraction of lamellipodia in spread platelets. Finally, inhibition of PAK resulted in the disaggregation of platelet aggregates formed under shear flow conditions. Together, these results demonstrate that the PAK signaling system is a key orchestrator of platelet actin dynamics, linking Rho GTPase activation to PAK effector function and platelet lamellopodia formation, thus filling an important gap in the understanding of platelet actin cytoskeletal organization. In addition, these data characterize the integral role of PAK in platelet spreading, aggregation, and aggregate stability. Elucidating the mechanisms that mediate platelet spreading and aggregate formation may highlight important steps in the platelet activation cascade at which to pharmacologically intervene in order to inhibit or treat pathologic thrombi formation. Disclosures: No relevant conflicts of interest to declare.

Abstract 5261 An increase in mean platelet volume (MPV) is correlated with platelet activation and subsequent shape change. Pathologic processes marked by increased platelet activity such as myocardial infarction, cerebral vascular accidents, diabetes mellitus, and hypertension are associated with an increased MPV. Elevated MPV in these conditions reflect both a higher level of platelet activation as well as increased platelet turnover secondary to platelet consumption within thrombus formation. Assessment of MPV can be used to risk stratify patients as well as assign them to prognostic categories. However, MPV does not assess platelet heterogeneity or the specific change in single platelet mass, volume, or density. Current methods provide little insight into changes in physical parameters at the single platelet level. In order to overcome this limitation, we developed a quantitative tomographic differential interference contrast (QTDIC) microscopy technique to measure dry mass, volume, and density of platelets at the single-cell level. This technique is based on determining the axially resolved refractive index from a series of through-focus DIC images. Single cell platelet mass was observed to reduce from 1.84 ± 0.14 pg to 1.60 ± 0.13 pg in response to stimulation with thrombin-receptor agonist peptide (TRAP), while single cell platelet volume reduced from 7.28 ± 0.56 fL to 6.03 ± 0.48 fL (mean ± SEM). Single cell platelet density increased from 0.25 ± 0.001 pg/fL to 0.26 ± 0.002 pg/fL (mean ± SEM). Taken together, we have characterized the physical parameters of platelets in response to agonist stimulation. Our data suggest that platelet activation may correlate with decreased mass and volume, perhaps as a consequence of platelet degranulation. Further elucidation of the morphological changes of activated platelets at the single platelet level may allow for better understanding of platelet function and dysfunction in patients affected by platelet granule deficiencies, giant platelet syndromes, and disorders associated with membrane receptorsFigure 1.Characterization of physical parameters of platelets. (a) DIC image of human platelets, (b) refractive index map, (c) dry mass density map determined from refractive index using the Barer calibration, (d) Histogram of platelet dry mass, (e) Histogram of platelet volume, (f) Histogram of platelet density.Figure 1. Characterization of physical parameters of platelets. (a) DIC image of human platelets, (b) refractive index map, (c) dry mass density map determined from refractive index using the Barer calibration, (d) Histogram of platelet dry mass, (e) Histogram of platelet volume, (f) Histogram of platelet density. Disclosures: No relevant conflicts of interest to declare.

Background: Children with ITP who are prescribedsecond line treatments vary in terms of their clinical phenotype, prior treatments, and health related quality of life (HRQoL). Objective: To describe the clinical characteristics and HRQoL of North American pediatric patients with ITP initiating second line treatments. Methods: A longitudinal observational cohort of 118 children with ITP starting second line treatments was enrolled from 2013-2015 at 21 ICON centers. Enrollment requirements included age 1-17y and starting a second line treatment (not IVIG, steroids or anti-D) as monotherapy. Baseline demographic and clinical characteristics were recorded, including response to prior treatments, worst bleeding scores, and baseline platelet counts. Fisher's exact test was used to compare treatment with phase of ITP, age cohort, and gender. HRQoL was measured by patient/caregiver report using the Kids ITP Tool (KIT) where 0 is worst and 100 is best, while physicians assessed the perceived effect of ITP on patient HRQoL using a 5-point scale. Spearman correlations were used to test for association between bleeding, HRQoL, and duration of ITP. ANOVA was used to compare the mean KIT scores of the treatment groups. Results: The clinical characteristics of the cohort are shown in the Table. Median age at enrollment was 11.4 y and 15% had newly diagnosed ITP, 31% had persistent ITP, and 54% had chronic ITP. The median number of prior treatments was 3 (range: 1-9). The prior response rate (platelet >30 x 109/µL and no bleeding) to prednisone was 59% and IVIG 66%. Fifty-five (47%) patients had received at least one prior second line treatment. At enrollment, physicians reported that ITP had impacted the patients' HRQoL severely in 15%, significantly in 44%, moderately in 38%, and almost not at all in 3%. The mean score of the child KIT report was 71.4 (SD 17.2), the parent proxy KIT was 64.7 (SD 16.4), and the parent impact KIT was 36.1 (SD 19.2). The physician's assessment of the patient's HRQoL significantly correlated with the child report (p Treatments selected for second line treatment included: rituximab (n=42), romiplostim (n=31), eltrombopag (n=20), oral immunosuppressants (n=16), splenectomy (n=4), and dapsone (n=3). The selected treatment was not significantly different by age, gender, baseline child KIT score, or duration of ITP. Baseline parent proxy KIT scores varied significantly between selected treatments (p=0.03) and were significantly lower in children starting on eltrombopag in comparison to romiplostim (56.4 (SD 15.1) vs. 70.3 (SD 15.1), respectively; p=0.03). Conclusions: Children with ITP starting on new second line treatments often have received multiple prior treatments and nearly half start these treatments prior to being diagnosed with chronic ITP, including 15% who were in the newly diagnosed phase. Physician assessment of patient HRQoL correlates well with child and parent proxy report of HRQoL. The number of prior treatments and worst bleeding score did not correlate with HRQoL. Longer duration of ITP was associated with a better HRQoL, suggesting that the level of concern related to ITP may lessen over time. Baseline KIT scores were significantly different in children starting on specific treatments. Future analysis will compare the change from baseline in HRQoL in children treated with second line therapies. Disclosures Grace: Agios Pharmaceuticals: Other: Scientific Advisor, Research Funding. Neufeld:Novartis: Consultancy. Bussel:Eisai: Membership on an entity's Board of Directors or advisory committees, Research Funding; Symphogen: Membership on an entity's Board of Directors or advisory committees; Shionogi: Membership on an entity's Board of Directors or advisory committees; Protalex: Membership on an entity's Board of Directors or advisory committees, Research Funding; Physicians Education Resource: Speakers Bureau; Prophylix Pharma: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Rigel Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding; Immunomedics: Research Funding; Cangene: Research Funding; GSK: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Boehringer Ingelheim: Research Funding; Ligand: Membership on an entity's Board of Directors or advisory committees, Research Funding; UpToDate: Patents & Royalties; Genzyme: Research Funding; BiologicTx: Research Funding; Momenta Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Sysmex: Research Funding; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Haley:Baxalta: Membership on an entity's Board of Directors or advisory committees; CSL Behring: Honoraria. Thompson:Baxalta (now part of Shire): Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; bluebird bio: Consultancy, Research Funding; Baxalta (now part of Shire): Research Funding; ApoPharma: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding; bluebird bio: Consultancy, Research Funding; Amgen: Research Funding; Mast: Research Funding; Mast: Research Funding; Celgene: Research Funding; Celgene: Research Funding; Eli Lily: Research Funding; Eli Lily: Research Funding.