Clinical and Outcomes Findings for Thrombotic Thrombocytopenic Purpura among 467 Persons with Severely Versus Not Severely Deficient ADAMTS-13 Levels.

Abstract Background: Thrombotic thrombocytopenic purpura (TTP) is a rare disorder that presents with microangiopathic hemolytic anemia and thrombocytopenia, fevers, renal insufficiency and neurologic features. We reviewed clinical, laboratory, and outcome data for TTP cases with severely deficient versus non-severely deficient ADAMTS13 activity levels. Methods: Mean and median data were from the Surveillance, Epidemiology and Risk Factors for TTP (SERF-TTP) study group for idiopathic TTP cases, the Canadian Apheresis Group (CAG), and five published series (Zheng 2004, Raife 2004, Vesely 2003 (Oklahoma TTP-HUS Registry), Matsumoto 2004 (Japan Referral Center), Bennett 2007). Results: Compared to TTP cases with near-normal ADAMTS13 activity levels (n= 282), TTP cases with severe ADAMTS13-deficiency (n=185) were more likely to have severe thrombocytopenia, normal renal function and neutralizing ADAMTS13 antibodies. Severe ADAMTS13 deficient TTP cases have better overall survival after therapeutic plasma exchange (TPE) but are more likely to relapse. TTP patients with severe ADAMTS13 deficiency were primarily categorized as idiopathic or ticlopidine-associated, while TTP patients with non-severely deficient ADAMTS13 activity levels were frequently categorized as idiopathic, secondary to drugs (clopidogrel, quinine), stem cell transplantation, or cancer. Conclusions: Severe ADAMTS13 deficiency is most commonly idiopathic, has better survival following TPE, and a 35–40% spontaneous relapse rate. By contrast, non-ADAMTS13 deficient TTP cases are usually associated with an underlying disorder or external insults. Amongst this cohort, four series have 47–62% survival rates and three series, which contain mostly idiopathic cases, have 83–90% survival rates following TPE. From this, we propose that TTP may occur by three possible mechanism; ADAMTS13-deficient (antibody-mediated), an immunologic mediated pathway independent of ADAMTS13 (i.e. quinine) that is responsive to TPE, and endothelial injury related TTP that is unresponsive to TPE. Platelet count mean (x10^9/L) Creatinine mean (mg/dl) ADAMTS13 neutralizing antibodies (%) Survival % Relapse % * <15% ADAMTS13 activity cutoff Severe ADAMTS13 Deficiency (<10–15%) SERF-TTP (n=30) 19 1.3 83 97 41 Zheng (n=16) 19 1.6 44 81 38 Bennett (n=26) 15 85 Oklahoma (n=18) 12 1.8 94 81 38 Raife (n=50) * 13 1.2 92 35 Japan (n=34) 35 91 Canada (n=11) 16 2.4 82 Not Severely Deficient ADAMTS13 Activity (> 15%) SERF-TTP (n=22) 57 3.9 35 90 0 Raife (n=57) * 44 2.7 83 9 Canada (n=17) 57 4.1 88 Zheng (n=13) 40 3.0 0 54 Bennett (n=13) 62 Japan (n=66) 9 62 Oklahoma (n=94 ) 23 47 3

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Complement Activation May Trigger the Onset of Thrombotic Thrombocytopenic Purpura in Patients with Severe ADAMTS13 Deficiency

Blood ◽

10.1182/blood.v124.21.600.600 ◽

2014 ◽

Vol 124 (21) ◽

pp. 600-600 ◽

Cited By ~ 2

Author(s):

Xiao-Hui Hu ◽

Jialing Bao ◽

Yoshiyasu Ueda ◽

Takashi Miwa ◽

Wenchao Song ◽

...

Keyword(s):

Thrombotic Thrombocytopenic Purpura ◽

Complement Activation ◽

Factor H ◽

Severe Thrombocytopenia ◽

Complement Factor ◽

Healthy Controls ◽

Adamts13 Activity ◽

Activation Markers ◽

Thrombocytopenic Purpura ◽

Adamts13 Deficiency

Abstract Thrombotic thrombocytopenic purpura (TTP), a potential fatal syndrome, is often associated with severe deficiency of plasma ADAMTS13 activity, either resulting from ADAMTS13 mutations or acquired anti-ADAMTS13 autoantibodies that inhibit plasma ADAMTS13 activity. Patients with severe ADAMTS13 do not always have TTP signs and symptoms, which often occur following infections or inflammatory responses. The mechanism of TTP flare is not fully understood. In the present study, complement activation markers (iC3b, C5b, Bb, and C4b) were determined by enzyme-linked absorbent assays (ELISA) in the initial plasmas (prior to plasma exchange) of 20 patients with acquired TTP with severe ADAMTS13 deficiency (less than 20% of normal) and plasmas from 20 healthy controls. Of 20 TTP patients, 19 exhibited positive inhibitor in the 50:50 mixing study. Plasma levels of iC3b (1,000 ± 1,062 ng/ml), sC5b-9 (1,342±867 ng/ml), and Bb (38.2±47.7 ng/ml), as well as C4b (74.3±49.5 ng/ml) in acquired TTP patients were significantly higher than those in healthy controls (p value less than 0.01) These results indicate that complement activation in both classic and alternative pathways is a common phenomenon in patients with acquired autoimmune TTP. To demonstrate the causative effect of complement activation in TTP, we turned to our Adamts13 null mice. C57BL/6 (Adamts13-/-) mice are resistant to the development of spontaneous and Shigatoxin-induced TTP syndrome. When injected with a murine specific monoclonal antibody against complement factor H (CFH) (800 micro grams/mouse), which inhibits binding of circulating CFH to endothelial cells and C3b, Adamts13-/- mice (C57BL/6) developed more severe thrombocytopenia and anemia than wild type mice did within 6 days without additional challenge. However, renal insufficiency manifested by the increase of plasma BUN concentration was similar in both groups (Fig. 1). These results indicate that complement activation through an alternative pathway, following antibody-mediated inhibition of CFH or other complement regulatory components, may trigger the onset of TTP in light of severe ADAMTS13 deficiency. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

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The remarkable diversity of thrombotic thrombocytopenic purpura: a perspective

Blood Advances ◽

10.1182/bloodadvances.2018018432 ◽

2018 ◽

Vol 2 (12) ◽

pp. 1510-1516 ◽

Cited By ~ 8

Author(s):

James N. George

Keyword(s):

Thrombotic Thrombocytopenic Purpura ◽

Immunosuppressive Treatment ◽

Severe Thrombocytopenia ◽

Adamts13 Activity ◽

Long Term Outcomes ◽

Thrombocytopenic Purpura ◽

Adamts13 Deficiency ◽

Few Data ◽

Autoimmune Etiology

Abstract Understanding the autoimmune etiology of acquired thrombotic thrombocytopenic purpura (TTP) has provided precision for the diagnosis and a rationale for immunosuppressive treatment. These advances have also allowed recognition of the remarkable clinical diversities of patients’ initial presentations and their long-term outcomes. These diversities are illustrated by the stories of patients from the Oklahoma TTP Registry. The initial presentation of TTP may be the discovery of unexpected severe thrombocytopenia in a patient with minimal or no symptoms. The patient may remain asymptomatic throughout treatment or may die suddenly before treatment can be started. ADAMTS13 activity may be reported as normal in a patient with characteristic clinical features of TTP, or the unexpected report of ADAMTS13 deficiency in a patient with another established disorder may lead to the discovery of TTP. ADAMTS13 activity during clinical remission is unpredictable. ADAMTS13 activity may recover and remain normal, it may remain severely deficient for many years, or it may become normal only many years after recovery. Our treatment of initial episodes and management of patients after recovery and during remission continue to change. The addition of rituximab to the treatment of acute episodes and preemptive rituximab for patients with severe ADAMTS13 deficiency during remission are reported to prevent relapse. Because TTP is uncommon, there are few data to guide these changes. Therefore our patients’ stories are profoundly influential. Their stories are the foundation of our experience, and our experience is the guide for our decisions.

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Ticlopidine- and Clopidogrel-Associated Thrombotic Thrombocytopenic Purpura (TTP): Final Results from the Surveillance Epidemiology and Risk Factor-TTP Study Group.

Blood ◽

10.1182/blood.v110.11.2089.2089 ◽

2007 ◽

Vol 110 (11) ◽

pp. 2089-2089

Author(s):

Elizabeth A. Richey ◽

Charles L. Bennett ◽

Hau C. Kwaan ◽

Anaadriana Zakarija ◽

Nicholas Banderanko ◽

...

Keyword(s):

Thrombotic Thrombocytopenic Purpura ◽

Neutralizing Antibodies ◽

Laboratory Data ◽

Package Insert ◽

Direct Result ◽

Reference Laboratory ◽

Adamts13 Activity ◽

Thrombocytopenic Purpura ◽

Chemical Structures ◽

Adamts13 Deficiency

Abstract Thrombotic thrombocytopenic purpura (TTP) is a microvascular occlusive disorder characterized by systemic aggregation of platelets, thrombocytopenia, and mechanical injury to erythrocytes. Between 30% and 80% of TTP cases are associated with ADAMTS13 deficiency. Thienopyridine-derivative anti-platelet agents, ticlopidine and clopidogrel, are the drugs most commonly associated with TTP. The structures differ only by a carboxymethyl side-chain and have no common metabolites. Since 2002, our R01 research project has focused on evaluating thienopyridine-associated TTP. Herein, we present the final results. Clinical and laboratory data were obtained from case reports, the FDA’s MedWatch program, a Japanese national reference laboratory for ADAMTS13 assays, and apheresis centers at Duke University, University of North Carolina, Northwestern University, and the Mayo Clinic. Epidemiologic data for rate estimation for thienopyridine-associated TTP among persons who receive cardiac stents were obtained from international cardiology laboratories. Pharmacovigilance information was obtained from package inserts for the drugs. Most thienopyridine-associated TTP cases are associated with two weeks or more of ticlopidine rather than clopidogrel, are immune-mediated involving neutralizing antibodies to ADAMTS13, resolve with therapeutic plasma exchange (TPE), and have spontaneous relapses. Less frequently, cases are associated with clopidogrel, occur within days of drug initiation, may be a direct result of endothelial cell damage, are less responsive to TPE, and are less likely to recur. Thienopyridine-associated TTP patients with severe deficiency of ADAMTS13 activity have a different profile than those with normal ADAMTS13 levels. Among thienopyridine-associated TTP patients who have ADAMTS13 deficiency, TPE is usually performed for a few days and patients recover without detectable organ damage. In contrast, among thienopyridine-associated TTP patients who do not have ADAMTS13 deficiency, several weeks of TPE is required for recovery, and 30% mortality rates have been reported. Despite similar chemical structures, ticlopidine- and clopidogrel-associated TTP probably occur by different mechanisms and have different clinical presentations and expected outcomes. Clinical Characteristics Onset Platelet Count <20,000 (%) Creatinine ≤2 mg/dl (%) Neurologic Symptoms (%) Mortality With TPE/Without TPE (%) Relapse *p < 0.05 ticlopidine 10%* <2 weeks; 90% 2-12 weeks 84* 28* 28 15/44 Occasional clopidogrel 74%*≤2 weeks; 26% > 2 weeks 60* 55* 32 28/33 Rare Epidemiology, Pharmacovigilance & Basic Science Incidence (cases per treated patients) Safety ADAMTS13 Activity (%) ADAMTS13 Antibodies (%) ticlopidine 1:1,600 “Black Box” warning <10* 90* clopidogrel 1:100,000 package insert warning 50–100* 10*

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Exome Sequencing Identifies Glycosylation Defects As a Probable Cause of Immune Thrombotic Thrombocytopenic Purpura

Blood ◽

10.1182/blood-2019-131511 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 217-217

Author(s):

Felipe Massicano ◽

Elizabeth M. Staley ◽

Konstantine Halkidis ◽

Nicole K. Kocher ◽

Lance A. Williams ◽

...

Keyword(s):

Exome Sequencing ◽

Thrombotic Thrombocytopenic Purpura ◽

Potential Contribution ◽

Severe Thrombocytopenia ◽

Adamts13 Activity ◽

Genomic Alterations ◽

Autoantibody Production ◽

Thrombocytopenic Purpura ◽

Long Term Outcome ◽

Clinical Presentations

Background: Immune thrombotic thrombocytopenic purpura (iTTP) is a potentially fatal syndrome, resulting primarily from autoantibodies against ADAMTS13. However, the mechanism underlying the autoantibody formation and the contribution of other genomic alterations to the pathogenesis of iTTP are largely unknown. Methods: Whole exome sequencing (WES) and bioinformatic analyses were performed to determine the genetic variations in 40 patients with iTTP who had ADAMTS13 activity <10 IU/dL and a positive inhibitor or an elevated anti-ADAMTS13 IgG in concordance with clinical presentations of severe thrombocytopenia and microangiopathic hemolytic anemia with various degrees of organ injury. WES was also performed at the same time in fifteen age-, gender-, and ethnicity- matched individuals who did not have a history of iTTP or other hematological disorders as controls. Results: WES identified variants or mutations in the genes involving in glycosylation, including O-linked glycosylation, to be the major pathway affected in patients with iTTP. We propose that the altered glycosylation may be responsible for the development of autoantibodies against ADAMTS13 which impair the proteolytic cleavage of von Willebrand factor, accelerate the clearance of ADAMTS13 from circulation, and result in severe thrombocytopenia platelets in patients with iTTP. We also identified defects in ankyrin repeat containing protein ANKRD36C, a protein with hitherto unknown function, as the most statistically significant genomic alterations associated with iTTP (p < 10-5). Moreover, candidate gene analysis revealed that various genes involving in hemostasis, complement activation, platelet function and signaling pathway, and inflammation were all affected in patients with iTTP, which may contribute to the onset, progress, severity, and long-term outcome of iTTP. Finally, we also identified two patient subgroups where the disease mechanism might be different. Conclusion: Our findings provide novel insight into the pathogenic mechanism underlying ADAMTS13 autoantibody production and the potential contribution of other genetic abnormalities in modifying the iTTP clinical presentations in the individuals with severe deficiency of plasma ADAMTS13 activity. Disclosures Zheng: Alexion: Speakers Bureau; Ablynx/Sanofi: Consultancy, Speakers Bureau; Shire/Takeda: Research Funding; Clotsolution: Other: Co-Founder.

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Risk Factors for Recurrence of Thrombotic Thrombocytopenic Purpura.

Blood ◽

10.1182/blood.v108.11.1060.1060 ◽

2006 ◽

Vol 108 (11) ◽

pp. 1060-1060 ◽

Cited By ~ 1

Author(s):

Flora Peyvandi ◽

Silvia Lavoretano ◽

Roberta Palla ◽

Hendrik B. Feys ◽

Tullia Battaglioli ◽

...

Keyword(s):

Risk Factors ◽

Relative Risk ◽

Thrombotic Thrombocytopenic Purpura ◽

Disease Recurrence ◽

Acute Episode ◽

Adamts13 Activity ◽

Thrombocytopenic Purpura ◽

Neutralizing Activity ◽

Adamts13 Deficiency

Abstract The introduction of plasma exchange therapy in early 1970s significantly reduced the rate of mortality in patients affected by thrombotic thrombocytopenic purpura (TTP), a disease characterized by thrombocytopenia and microangiopathic hemolytic anemia. A similar improvement was never achieved in the prevention of the disease recurrence. Still, 20–50% of patients, who survived the fatal disease, experience a relapse one month or even years after the acute episode of TTP. There is no pathognomic marker or laboratory test that can be used for the surveillance of TTP during remission and predict which patients will relapse. We have retrospectively analyzed for the first time at remission the role of ADAMTS13, anti-ADAMTS13 autoantibodies and von Willebrand Factor (VWF) in 109 patients who survived the acute episode of TTP. ADAMTS13 activity and ADAMTS13 antigen levels were measured as described by Gerritsen et al (TH 1999) and Feys HB et al. (JTH 2006), respectively. The total anti-ADAMTS13 autoantibodies (with and without neutralizing activity) were measured by western blot analysis and the presence of neutralizing anti-ADAMTS13 autoantibodies was checked according to Gerritsen et al (TH 1999). VWF antigen was measured using an ELISA assay and VWF multimers analysis was carried out using low-resolution SDS-agarose gel electrophoresis and exposing gels to human anti-VWF antibodies labeled with I125 for autoradiography (Ruggeri & Zimmerman, Blood 1981). All variables have been statistically analyzed in 2 subgroups of patients with or without TTP recurrence, in order to understand the role of each variable as a potential predictor marker for recurrence. Univariate and multivariate analysis were carried out to evaluate adjusted and unadjusted odds ratios (Ors) with 95% confidence intervals (CI) as a measure of the relative risk of relapse associated with the risk factors under investigation. Our data showed that the median value of ADAMTS13 activity and antigen levels at remission were significantly lower in patients with recurrent TTP than in patients with no relapse (ADAMTS13 activity: 12% vs. 41%; p=0.007; ADAMTS13 antigen: 36% vs 58%; p=0.003). Furthermore, the prevalence of patients with severe ADAMTS13 deficiency (≤10%) was significantly higher in the group of patients who relapsed (OR=2.9 CI95% 1.3–6.8, p=0.01). The prevalence of anti-ADAMTS13 autoantibodies (with or without neutralizing activity) resulted to be significantly higher in patients with recurrent TTP (OR= 3.1 CI 95% 1.4–7.3, p=0.006). A higher VWF antigen levels or the presence of ultralarge VWF (ULVWF) multimers at remission did not increase the risk of recurrence (p=0.4 for VWF:Ag and p=0.7 for ULVWF multimers). In conclusion, our data showed that the association of severe ADAMTS13 deficiency and the presence of anti-ADAMTS13 autoantibodies is a negative prognostic marker at remission and increases the relative risk of TTP recurrence by 3.6 times (OR=3.6 CI95% 1.4–9). Therefore our results would suggest that our efforts should go in the direction of maintenance therapy which aims at reducing or abolishing the presence of antibodies during remission and increasing the level of ADAMTS13 in plasma in order to prevent the recurrence of TTP.

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Thienopyridine-Associated Thrombotic Thrombocytopenia Purpura: Updated Antibody Results From the SERF-TTP Study.

Blood ◽

10.1182/blood.v114.22.892.892 ◽

2009 ◽

Vol 114 (22) ◽

pp. 892-892

Author(s):

Anaadriana Zakarija ◽

Thanh Ha Luu ◽

Hau C. Kwaan ◽

June McKoy ◽

Ivy Weiss ◽

...

Keyword(s):

Plasma Exchange ◽

Neutralizing Antibodies ◽

Conflicts Of Interest ◽

Therapeutic Plasma Exchange ◽

Severe Thrombocytopenia ◽

Adamts13 Activity ◽

Laboratory Findings ◽

History Of ◽

Adamts13 Deficiency ◽

Drug Dependent

Abstract Abstract 892 Background: The thienopyridines, ticlopidine and clopidogrel, have been associated with thrombotic thrombocytopenia purpura (TTP). However, few studies have reported information on antibodies to ADAMTS13 among patients with thienopyridine-associated TTP. We previously reported on two mechanistic pathways of thienopyridine-associated TTP with some overlapping features. Evaluation of ADAMTS13 autoantibodies was undertaken to improve understanding of these syndromes. Methods: Clinical and laboratory findings were evaluated for 30 ticlopidine-, 10 clopidogrel-associated TTP cases, and 54 cases of idiopathic TTP. Results: Among patients with thienopyridine-induced TTP, those with a history of ticlopidine versus clopidogrel use were more likely to present with severe thrombocytopenia (platelet < 20,000) (90% versus 13%), severe ADAMTS13-deficiency (80% versus 0%), and neutralizing antibodies to ADAMTS13 (100% versus 0%), and were less likely to have less than a two week history of thienopyridine exposure (0% versus 50%) (p<0.05 for each comparison). They were also more likely to survive following therapeutic plasma exchange (TPE) (85% versus 50%). 2 patients exposed to clopidogrel later relapsed and had similar characteristics to idiopathic TTP patients with non-deficient ADAMTS13 activity. Conclusion: Ticlopidine causes TTP by a pathway involving a neutralizing autoantibody to ADAMTS13 while clopidogrel causes TTP by an ADAMTS13-independent pathway. Although ADAMTS13 autoantibodies are present in both idiopathic and ticlopidine-associated TTP, spontaneous relapses are not seen in ticlopidine-associaated TTP, suggesting that drug-dependent antibodies are present. Clopidogrel associated TTP is distinct from idiopathic TTP in that ADAMTS13 autoantibodies are absent and response to TPE is poor. Disclosures: No relevant conflicts of interest to declare.

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Clinical Characteristics of Thrombotic Thrombocytopenic Purpura with Severe ADAMTS13 Deficiency

Blood ◽

10.1182/blood.v116.21.4666.4666 ◽

2010 ◽

Vol 116 (21) ◽

pp. 4666-4666

Author(s):

Moon Jang ◽

So Young Chong ◽

Inho Kim ◽

Chul W. Jung ◽

Doyeun Oh

Keyword(s):

Mortality Rate ◽

Serum Creatinine ◽

Thrombotic Thrombocytopenic Purpura ◽

Clinical Significance ◽

Sodium Dodecyl ◽

Prognostic Significance ◽

Adamts13 Activity ◽

Lower Serum ◽

Thrombocytopenic Purpura ◽

Adamts13 Deficiency

Abstract Abstract 4666 The clinical significance of ADAMTS13 activity for response to treatment, mortality rate, recurrence, and prognosis is unclear. Therefore, we investigated the characteristics of severe ADAMTS13 deficiency and evaluated its clinical significance in Thrombotic thrombocytopenic purpura (TTP). The Korean TTP Registry includes 66 patients from 13 teaching hospitals in Korea who received the diagnosis of TTP from January 2005 to December 2008. Blood samples obtained upon admission were sent for ADAMTS13 analysis (multimer analysis by sodium dodecyl sulfate electrophoresis and/or ELISA) to a central laboratory along with patient clinical information. After 6 months, patient data regarding treatment, response, and prognosis were collected on standardized report forms. Patients with severe ADAMTS13 deficiency had lower serum creatinine levels (P=0.001) and WBC counts (P=0.050) than patients with non-severe ADAMTS13 deficiency. Although severe ADAMTS13 deficiency was associated with better response rate (75% vs 53%, P=0.145), remission rate (81% vs 61%, P=0.209), and mortality rate (19% vs 31%, P=0.508) than non-severe ADAMTS13 deficiency, treatment outcomes did not differ significantly between groups. After adjusting for clinical and laboratory features, multivariate analysis did not reveal any independent risk factors for TTP-associated mortality. Patients with severe ADAMTS13 deficient had lower serum creatinine levels and WBC counts at presentation but Severe ADAMTS13 activity deficiency at TTP diagnosis does not appear to have prognostic significance. Disclosures: No relevant conflicts of interest to declare.

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Ticlopidine-, Clopidogrel-, and Prasugrel-Associated Thrombotic Thrombocytopenic Purpura: A Twenty Year Review

Blood ◽

10.1182/blood.v118.21.2226.2226 ◽

2011 ◽

Vol 118 (21) ◽

pp. 2226-2226

Author(s):

Zaina Parvez Qureshi ◽

John Armstrong ◽

Charles Bennett

Keyword(s):

Thrombotic Thrombocytopenic Purpura ◽

Survival Rates ◽

Epidemiologic Study ◽

Phase Iii ◽

World Health ◽

First Year ◽

Thrombocytopenic Purpura ◽

Pharmaceutical Manufacturers ◽

Adamts13 Deficiency ◽

Health Organization

Abstract Abstract 2226 Objective: Thrombotic thrombocytopenic purpura (TTP) is a rare syndrome, with our group having identified the thienopyridines ticlopidine and clopidogrel as the most common drugs associated with TTP in Food and Drug Administration (FDA) databases. We review clinical, epidemiologic, laboratory, and drug safety findings for thienopyridine-associated TTP, including the first reported cases with prasugrel, a thienopyridine approved in 2009. Methods: Data sources included FDA's Adverse Event Reports database, pharmaceutical manufacturers, package inserts, physician surveys, phase III reports, insurance databases, and an epidemiologic study (1989–2011). Causality was assessed with the World Health Organization scale. Results: Since 2002, FDA received reports of 10 ticlopidine-, 140 clopidogrel-, and nine prasugrel-associated TTP cases, including four, 11, and 9 cases respectively, in the first year of marketing of each agent. Surveys of hematologists by our group identified 32 ticlopidine- and ten clopidogrel-associated TTP cases. Thienopyridines were administered for > two weeks for 90% of 93 ticlopidine-associated cases, 26% of 35 cases clopidogrel-associated cases, and none of nine prasugrel-associated cases. In the Phase III setting, one of 2,932 ticlopidine-, none of 27,961 clopidogrel-, and none of 1,769 prasugrel-treated patients developed TTP. Insurance databases identified three clopidogrel-associated TTP case among 15.3 million individuals. Ticlopidine- (n=30) versus clopidogrel-associated TTP patients (n=8) presented with severe ADAMTS13-deficiency (80% versus 0%) and neutralizing auto-antibodies to ADAMTS13 (100% versus 0%) and had higher survival rates following therapeutic plasma exchange (87% versus 50%) (p<0.05). Greater than 95% of ticlopidine-associated TTP cases were assessed as having a probable causal relationship versus none of the clopidogrel- or prasugrel-associated TTP cases. TTP is described in a Black Box warning for ticlopidine (1998, incidence of 1 in 2,000) and as a warning for clopidogrel (2000; 12 per million) and prasugrel (2010; no incidence reported) Conclusion: TTP is associated with all thienopyridines, although causal relationships remain under active investigations. Disclosures: Armstrong: LeadHorse Technologies Inc.: Employment.

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Correlation Of ADAMTS13 Activity With Baseline Characteristics and Management Patterns In Patients With Suspected Thrombotic Thrombocytopenic Purpura In The State Of Rhode Island

Blood ◽

10.1182/blood.v122.21.3556.3556 ◽

2013 ◽

Vol 122 (21) ◽

pp. 3556-3556

Author(s):

Nathan T. Connell ◽

Joseph D. Sweeney

Keyword(s):

Plasma Exchange ◽

Thrombotic Thrombocytopenic Purpura ◽

Rhode Island ◽

Turnaround Time ◽

Activity Level ◽

Activity Levels ◽

Adamts13 Activity ◽

Thrombocytopenic Purpura ◽

Baseline Characteristics ◽

Pre Treatment

Abstract Introduction While the activity level of ADAMTS13 can be helpful in diagnosing patients with thrombotic thrombocytopenic purpura (TTP), the current long turnaround time of this test for most institutions limits its role in early clinical decision-making about the initiation of plasma exchange. Levels of ADAMTS13<10% are pathognomonic of TTP and levels in excess of 10% indicate an alternate cause of thrombotic microangiopathy. The aim of the study was to look at recent practice in the State of Rhode Island regarding the criteria for initiation of plasma exchange with a subsequent categorization of those patients based on ADAMTS13 activity levels. Methods Patients with a diagnosis of TTP were identified from hospital records of the major hospitals in Rhode Island which perform therapeutic apheresis in calendar years 2011 and 2012. From a chart review and blood bank records, baseline clinical parameters were collected, the number of therapeutic plasma exchanges (TPE) performed and the volume of plasma utilized. Pre-treatment ADAMTS13 activity was recorded if available in addition to the number of days from the initiation of TPE to test result availability. An analysis was performed to examine if patients who had a pre-treatment ADAMTS13 activity level ≤10% differed in baseline characteristics or response to TPE from those with activity levels >10%. Based on the normality of the distribution of the data, independent t-tests or Wilcoxon rank-sum tests were performed using SAS version 9.3. Results During this two year period, 24 patients received plasma exchange in Rhode Island for a presumptive diagnosis of TTP. The mean age was 47 years (range 20-89 years) and 38% were male. ADAMTS13 activity was available for 20 patients and 7 (30% of those exchanged) had documented pre-treatment activity levels ≤10% consistent with TTP. The median turnaround time for the ADAMTS13 assay was 10 days (range 2-52). Mean baseline parameters at the time of presentation are shown in the table. As expected, creatinine levels were lower in those patients with true TTP (p=0.0410). ADAMTS13 activity level was predictive of the number of days to a platelet count ≥150 x 109/L (Pearson correlation 0.56; p-value 0.0458). Overall, 4238 units of plasma were utilized for exchange. Of these 4238 units, 1886 were transfused to patients who were subsequently shown to have an ADAMTS13 activity >10%, and 813 of the 1886 units (20% of all plasma exchanged) were transfused after the results of enzyme activity were available in this population. Conclusions Based on an ADAMTS13 >10%, a significant volume of plasma was unnecessarily transfused. Reducing the turnaround time for the ADAMTS13 assay in tertiary care centers could help clinicians better determine which patients will benefit from plasma exchange, avoiding the morbidity and expense associated with large volume plasma exchange. Disclosures: No relevant conflicts of interest to declare.

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FRETS-VWF73 rather than CBA assay reflects ADAMTS13 proteolytic activity in acquired thrombotic thrombocytopenic purpura patients

Thrombosis and Haemostasis ◽

10.1160/th13-08-0688 ◽

2014 ◽

Vol 112 (08) ◽

pp. 297-303 ◽

Cited By ~ 13

Author(s):

Ilaria Mancini ◽

Carla Valsecchi ◽

Luca Lotta ◽

Louis Deforche ◽

Silvia Pontiggia ◽

...

Keyword(s):

Thrombotic Thrombocytopenic Purpura ◽

Proteolytic Activity ◽

Binding Activity ◽

Adamts13 Activity ◽

Flow Conditions ◽

Thrombocytopenic Purpura ◽

Severe Deficiency ◽

Adamts13 Deficiency ◽

Von Willebrand ◽

Willebrand Factor

SummaryCollagen-binding activity (CBA) and FRETS-VWF73 assays are widely adopted methods for the measurement of the plasmatic activity of ADAMTS13, the von Willebrand factor (VWF) cleaving-protease. Accurately assessing the severe deficiency of ADAMTS13 is important in the management of thrombotic thrombocytopenic purpura (TTP). However, non-concordant results between the two assays have been reported in a small but relevant percentage of TTP cases. We investigated whether CBA or FRETS-VWF73 assay reflects ADAMTS13 proteolytic activity in acquired TTP patients with non-concordant measurements. Twenty plasma samples with non-concordant ADAMTS13 activity results, <10% using FRETS-VWF73 and ≥20% using CBA, and 11 samples with concordant results, <10% using either FRETS-VWF73 and CBA assays, were analysed. FRETS-VWF73 was performed in the presence of 1.5 M urea. ADAMTS13 activities were also measured under flow conditions and the VWF multimer pattern was defined in order to verify the presence of ultra-large VWF due to ADAMTS13 deficiency. In FRETS-VWF73 assay with 1.5 M urea, ADAMTS13 activity significantly increased in roughly 50% of the samples with non-concordant results, whereas it remained undetectable in all samples with concordant measurements. Under flow conditions, all tested samples showed reduced ADAMTS13 activity. Finally, samples with non-concordant results showed a ratio of high molecular weight VWF multimers higher than normal. Our results support the use of FRETS-VWF73 over CBA assay for the assessment of ADAMTS13 severe deficiency and indicate urea as one cause of the observed differences.

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