Relapsed Refractory Acquired Thrombotic Thrombocytopenic Purpura (aTTP) Following COVID-19 Vaccination

Abstract Introduction: Acquired thrombotic thrombocytopenic purpura (aTTP) due to an acquired deficiency in the enzyme ADAMTS13 leads to ultra-large von Willebrand multimers, thrombocytopenia and microangiopathic hemolytic anemia. Complications include microvascular and macrovascular thrombosis. We present an unusual case of a patient with a history of refractory aTTP who experienced relapsed aTTP following COVID-19 vaccine. Case Description: A 57-year-old African-American male with a history of refractory aTTP experienced a relapse following 3 years of remission after receiving COVID-19 vaccination. The patient was initially diagnosed with aTTP in 2016, after presenting with symptoms of dark urine, mild headaches and transient episodes of aphasia and paresthesia. Due to symptoms and persistently low ADAMTS13 levels, he required prolonged and extensive treatment including over 5 weeks of daily therapeutic plasma exchange (TPE), followed by gradual reduction in frequency of TPE sessions, as well as trials of rituximab, eculizumab, steroids, mycophenolate mofetil and bortezomib. Ultimately, he achieved remission after 9 months of intermittent TPE, 3 months of weekly bortezomib 1 mg/m 2, mycophenolate mofetil up-titrated to 1,750 mg twice daily, and then slowly tapered off over a 2-year period. The patient was doing well for 3 years without manifestations of aTTP (2 years off all therapeutics), until he developed a petechial rash 7 weeks after receiving the second dose of the Moderna COVID-19 vaccine. He was found to have acute thrombocytopenia with platelets of 38 x 10 9/L (normal range 135-317 x 109/L), from a baseline of 200-300 x 10 9/L. He was referred to the emergency department, where additional labs were notable for mildly elevated LDH of 508 U/L (normal range 122-222 U/L), hemoglobin of 12.4 g/dL (normal range 13.2-16.6 g/dL), creatinine at baseline, and peripheral blood smear showing 1-3 schistocytes per high-powered field. ADAMTS13 activity level was t <5% (normal >/= 70%), with positive ADAMTS13 inhibitor screen and titer of 1.5 (normal <0.4), consistent with relapsed aTTP. The patient was admitted to the hospital, and initiated on daily TPE, with steroids and diphenhydramine prior to each TPE session. He quickly improved with TPE alone , but given his history of refractory aTTP, he was discharged on weekly rituximab for 4 weeks and caplacizumab 11 mg daily for 30 days. His platelets remained stable within the upper limit of normal during his 30 day course of caplacizumab. However, 3 weeks after completion of caplacizumab, he had an acute drop in his platelets to 23 x 10 9/L. His ADAMTS13 level was again found to be <5%, and inhibitor level was the highest that it had ever been at 11.4. He was again hospitalized and underwent 8 sessions of daily TPE, as well as re-initiation of caplacizumab, mycophenolate mofetil 500 mg bid (with increasing taper), and a prednisone taper. Intravenous Cyclophosphamide 750 mg/m 2 was also added every 3 weeks. With this regimen, patient's platelet count normalized and remain stable, and his ADAMTS13 activity level has reached 52-59%. Discussion: Cases of vaccine-induced immune thrombotic thrombocytopenia (VITT) have been described as a complication following vaccination with formulations containing replication-defective adenoviral vectors (AstraZeneca-Oxford and Johnson&Johnson COVID-19 vaccines)(Arepally and Ortel 2021, Simpson, Shi et al. 2021). VITT and aTTP are both immune-mediated, however, VITT is distinct and pathogenically linked to autoimmune heparin-induced thrombocytopenia (HIT), given the presence of anti-platelet factor 4 antibodies in these patients, whereas aTTP is due to reduction in ADAMTS13 level, secondary to an antibody inhibitor of ADAMTS13 (Arepally and Ortel 2021). Recently, cases have been reported of de novo aTTP developing shortly after COVID-19 vaccination with all available vaccines, except the Moderna (mRNA-1273) vaccine (Al-Ahmad, Al-Rasheed et al. 2021, de Bruijn, Maes et al. 2021, Maayan, Kirgner et al. 2021, Ruhe, Schnetzke et al. 2021, Waqar, Khan et al. 2021, Yocum and Simon 2021). Additionally, cases of relapsed aTTP have been described following only the BNT162B2 (Pfizer-BioNTech) vaccine (Maayan, Kirgner et al. 2021, Sissa, Al-Khaffaf et al. 2021). This is the first case, to our knowledge, reported in the literature of aTTP following vaccination with Moderna's mRNA-1273 vaccine. Disclosures No relevant conflicts of interest to declare.

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A Rare Case of Delirium: Acquired Thrombotic Thrombocytopenic Purpura in an HIV Patient

Blood ◽

10.1182/blood-2018-99-120231 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 5007-5007

Author(s):

Kinjal Solanki ◽

Syed Haris A Pir ◽

Constantine Khoury ◽

Jose F. Cervantes

Keyword(s):

Hiv Infection ◽

Thrombotic Thrombocytopenic Purpura ◽

Hemolytic Anemia ◽

Conflicts Of Interest ◽

Activity Level ◽

Needle Stick Injury ◽

Adamts13 Activity ◽

Presumptive Diagnosis ◽

Thrombocytopenic Purpura ◽

Low Levels

Abstract Introduction Thrombotic thrombocytopenic purpura (TTP) is a rare disorder with incidence of one in a million. Manifestations of TTP include fever, thrombocytopenia, thrombotic microangiopathy affecting the brain, heart and kidney causing neurological symptoms, and hemolytic anemia. Not all patients with TTP will have each and every manifestation, and therefore a high index of suspicion is necessary when managing a patient with microangiopathic hemolytic anemia and thrombocytopenia. In recent years, increased incidence of TTP has been reported in patients with coexisting Human immunodeficiency virus (HIV)infection . Clinical Case A 55 year old female with unknown past medical history presented with confusion and altered sensorium after she was found in the airport wandering. When questioned, she was oriented to self only, and gave single phrase answers. Vitals on admission were significant only for tachycardia with HR of 125 beats per minute. Rest of physical exam was normal. Lab work revealed severe anemia (Hemoglobin 5.1), thrombocytopenia ( Platelet count 6), borderline renal function( BUN 30, serum Creatinine 1.1) and Schistocytes on peripheral smear. TTP was the presumptive diagnosis. Without evidence of sepsis, she was treated with intravenous fluids, systemic steroids, blood products (pure red cell concentrate and fresh frozen plasma) and plasmapheresis. Patient was found to be HIV positive, and had acquired immunodeficiency syndrome with CD4 count of 193. ADAMTS13 inhibitor was 1.3 (nl <0.4) and ADAMTS13 activity level was <3 (normal range 68-163%). Patient's mental status improved to baseline over next 3 days and, renal failure and encephalopathy resolved. Upon further investigation, she recalled having a needle stick injury around 10 years ago. She was started on elvitegravir, cobicistat, emtricitabine, and tenofovir alafenamide (Genvoya) and prophylactic antibiotics prior to discharge. Discussion Despite its rare nature, TTP can be fatal if one fails to make a proper timely diagnosis. If left untreated, the mortality can reach up to 90% but with empiric treatment and therapeutic plasma exchange up to 85% survival rate can be achieved. Through this case report, we hope to raise the awareness of this disorder with its particular association with HIV infection. The exact mechanism for HIV related TTP is unknown, but some proposed ones include the release of large amounts of von Willebrand factor and downregulation of ADAMTS13 and/or the production of antibodies against ADAMTS13. ADAMTS13 activity levels below 10% are seen in acquired and hereditary TTP, but not all patients with such exhibit low levels with this assay. Acquired TTP with low levels of ADAMTS13 has been increasingly reported in association with HIV infection, such as in this case. Disclosures No relevant conflicts of interest to declare.

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Investigation of Side Effects of Plasmaexchange In the Treatment of Thrombotic Thrombocytopenic Purpura

Blood ◽

10.1182/blood.v116.21.4661.4661 ◽

2010 ◽

Vol 116 (21) ◽

pp. 4661-4661

Author(s):

Sarah Steinemann ◽

Tanja Falter ◽

Mirjeta Qorraj ◽

Thomas Vigh ◽

Inge Scharrer

Keyword(s):

Side Effects ◽

Thrombotic Thrombocytopenic Purpura ◽

Side Effect ◽

Conflicts Of Interest ◽

Allergic Reactions ◽

Adamts13 Activity ◽

Plasma Therapy ◽

Thrombocytopenic Purpura ◽

Wide Range ◽

Von Willebrand

Abstract Abstract 4661 Introduction: Thrombotic thrombocytopenic purpura (TTP) is characterized by thrombocytopenia, hemolytic anemia and microthrombi. A deficiency of the metalloprotease ADAMTS 13, which cleaves a Tys1605-Met1606 bond in the A2 subunit of von Willebrand factor (VWF), leads to formation of ultra large von Willebrand multimers (UL-VWF) and can cause platelet aggregation and mircovascular thrombosis. Treatment of choice is the substitution of plasma with plasmaexchange. There are two different plasma types available: Fresh Frozen Plasma (FFP) and solvent/detergent (s/d) treated plasma. This treatment may carry significant risks and side effects for the patients. Therefore we investigated the side effects of the therapy and furthermore the ADAMTS13 activity of the two plasma types. Methods: A questionnaire was send to 66 TTP patients of the Department of Hematology to evaluate different side effects of the therapy. 20 batches of FFP and 4 batches of s/d plasma of all blood groups were investigated on ADAMTS13 activity. The ADAMTS13 activity was detected with BCS-Method according to Böhm and two commercial FRET assays. Results: So far 34 patients were inquired about age, weight and suspected trigger situations that might have caused their TTP manifestation. The mean age of the patients was 34 years with a mean weight of 70kg. A previous infection caused TTP manifestation in 42% of the patients; drug therapy (22%) and pregnancy (17%) were other mentioned triggers. 94% of the patients suffered from an acquired TTP and only 6% had a hereditary TTP. The patients had 2.88 relapses and were treated with 16.27 plasmaexchanges. 56% had an additional therapy with Rituximab to achieve a faster remission of the disease. These patients needed less plasmaexchanges for recovery, which proofed to be significant at 2% level in a one sided t-test. Tingling (64.7%) and shivering (51%) were the most often mentioned side effects and simultaneously described as the strongest. Shivering was significantly correlated to tachycardia (p<0.01). Headaches were significantly correlated to hot flushes, tingling and collapse (p< 0.05). Side effects and allergic reactions occurred in the therapy with FFP as well as with s/d plasma. Another side effect was the complication that came along with infection of the venous access. Most patients had a central venous catheter (72%) and described infections and pruritus (60%), 50% of them mentioned this complication more than once. We found in usual FFP slightly higher ADAMTS13 activity levels (696.97 ng/ml) than in s/d virus inactivated plasma (643.86 ng/ml). The ADAMTS13 activity varied between the different assays (normal range: 666 ± 135ng/ml). Conclusion: Our investigation demonstrated that plasmaexchange therapy is still associated with a wide range of side effects. Side effects of plasmaexchange that were most frequently described by patients were tingling and shivering. Headaches also occurred in various cases. Patients suffered generally from more than one side effect at the same time during the treatment. Allergic reactions to the plasma therapy were mentioned by 65% of the patients. Disclosures: No relevant conflicts of interest to declare.

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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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Evaluation of Clotting Factor Concentrates for Treatment of Thrombotic Thrombocytopenic Purpura.

Blood ◽

10.1182/blood.v116.21.3678.3678 ◽

2010 ◽

Vol 116 (21) ◽

pp. 3678-3678

Author(s):

Tanja Falter ◽

Mirjeta Qorraj ◽

Sarah Steinemann ◽

Thomas Vigh ◽

Inge Scharrer

Keyword(s):

Human Plasma ◽

Thrombotic Thrombocytopenic Purpura ◽

Blood Group ◽

Conflicts Of Interest ◽

Blood Groups ◽

Clotting Factor ◽

Plasma Samples ◽

Adamts13 Activity ◽

Thrombocytopenic Purpura ◽

Clotting Factor Concentrates

Abstract Abstract 3678 Introduction: Thrombotic thrombocytopenic purpura (TTP) is characterized by microthrombi, hemolytic anemia as well as thrombocytopenia. These symptoms are caused by a decreased activity of the protease ADAMTS13 which cleaves the von Willebrand Factor (VWF), due to mutation of the ADAMTS13-gene or autoantibodies. At the moment, the only available immediate therapy is plasmapheresis with Fresh Frozen Plasma (FFP) which may induce side effects. Therefore an alternative therapy might be the treatment with clotting factor concentrates. Methods: 40 plasma samples were tested, consisting of FFP and solvent/detergent treated plasma, four batches of each blood group; VWF/VIII concentrates (Wilate®; Wilfactin®; Haemate®P; Immunate®; Kogenate®, Beriate®). In all samples ADAMTS13 activity, antigen and autoantibodies against ADAMTS13 were investigated. Additionally, the samples were tested for the presence of ultralarge VWF multimers. The BCS method according to Böhm, two ELISAs (Technozym®ADAMTS13 and Actifluor™ADAMTS13) and the electrophoresis on a SDS gel were used. Results: ADAMTS13 activity was found in all VWF)VIII concentrates, which are produced from human plasma, but only with a very low activity (Wilate® 5.6%; Wilfactin® 2.8%; Haemate®P 13%; Immunate® 3.7%). ADAMTS13 activity was not detectable in the factor VIII concentrates (Kogenate® <2%; Beriate® <2%). Usual FFP and solvent/detergent treated plasma samples, contained much higher ADAMTS13 activity and antigen values than concentrates (FFP 78.6%, solvent/detergent treated plasma 77.6%). However a difference of activity between individual blood groups was evident in FFP samples (blood group A 69.4%; B 64.9%; AB 98.1%; 0 82.0%). Ultralarge VWF multimers could be demonstrated in VWF containing concentrates, less in VIII concentrate from human plasma and not in FFP and solvent/detergent treated plasma samples. As expected recombinant-produced VIII concentrate contained no traces of ultralarge VWF. In all analyzed samples antibodies were negative. Conclusion: For therapy of TTP clotting factor concentrates cannot be used as an alternative to the usual FFP and solvent/detergent treated plasma, because their ADAMTS13 activity values are too low. In addition, the VWF/VIII concentrates contain higher quantities of ultralarge VWF multimers, which are contraindicated for TTP patients. The differences of ADAMTS13 activity in FFP samples varies between the individual blood groups and batches. Solvent/detergent treated plasma shows less variation in ADAMTS13 activity due to the manufacturing process involving plasma pooling. Disclosures: No relevant conflicts of interest to declare.

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Retrospective Analysis of Patients Afflicted with Thrombotic Thrombocytopenic Purpura: A Single Institutional Experience.

Blood ◽

10.1182/blood.v120.21.2200.2200 ◽

2012 ◽

Vol 120 (21) ◽

pp. 2200-2200

Author(s):

Manali K. Kamdar ◽

Phillip Chae ◽

Maria Javaid ◽

Negin Mesaghian ◽

Kevin O'Brien ◽

...

Keyword(s):

Retrospective Analysis ◽

Thrombotic Thrombocytopenic Purpura ◽

Blood Group ◽

Conflicts Of Interest ◽

Severe Thrombocytopenia ◽

Adamts13 Activity ◽

Thrombocytopenic Purpura ◽

Congenital Deficiency ◽

Predominant Symptom ◽

Threatening Condition

Abstract Abstract 2200 Introduction: Thrombotic Thrombocytopenic Purpura (TTP) is an acute life threatening condition characterized by thrombocytopenia, microangiopathic hemolytic anemia, with or without renal failure or neurologic abnormalities, and without another cause for thrombotic microangiopathy. The majority of cases of TTP are associated with a low ADAMTS13 activity which results from antibody to this enzyme. A minority of patients have TTP secondary to congenital deficiency of this enzyme. The mainstay of therapy for TTP is plasmapheresis (PEX) which has increased survival in affected patients from 10% to more than 75%. While TTP is considered as an uncommon disorder, at our institution we suspected that the diagnosis was made more commonly. Therefore we set out to perform a retrospective analysis of cases of TTP to evaluate cases diagnosed over the past 10 years. Methods: We performed a retrospective analysis of all cases of microangiopathy undergoing pheresis at our institution for presumed TTP from May 2007 to April 2012. A total of 112 patients had PEX initiated for presumed TTP however 11 of these were later determined to have some other etiology causing the constellation of symptoms and PEX was discontinued. The remaining 101 patients were entered into a database and further analyzed. Demographically, we captured patients from 30 of the 100 North Carolina counties because 3 other institutions in our state perform plasma exchange for TTP. ADAMTS13 activity and inhibitor levels were measured in 69 out of 101 patients. In our registry there were 80 patients with Idiopathic TTP and 21 patients with secondary TTP. Patients with idiopathic TTP were further divided based on the ADAMTS13 activity. Results: Discussion: Our analysis demonstrated that TTP was more common in females, African American population with a median age group in the mid forties with neurological symptoms being the predominant symptom of presentation. While hematocrit was higher in patients with idiopathic TTP these patients were noted to have increased incidence of ADAMTS13 levels less than 10% with inhibitors as compared to those with secondary TTP. Idiopathic TTP patients had more incidence of multiple relapses and required more Rituximab in addition to PEX. We compared our results with the results published from the Oklahoma registry. Similar to the Oklahoma registry results patients with ADAMTS13 levels less than 10% had more severe thrombocytopenia, renal dysfunction, required more sessions of PEX, had higher relapses and percentage of death compared to patients with idiopathic TTP with ADAMTS13 levels more than 10%. Patients with ADAMTS13 less than 10% required more Rituximab during first diagnosis of idiopathic TTP. In this group blood group A+ was seen more often whereas blood group O+ was prevalent in the group with ADAMTS more than 10%. Comparison amidst these groups brought out similarities between two distinct registries in the US. Our registry is another large registry of patients similar to the Oklahoma TTP registry. While many similarities are seen with the Oklahoma group there were a few differences as cited above. Disclosures: No relevant conflicts of interest to declare.

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Preemptive Rituximab Infusions Efficiently Prevent Relapses In Acquired Thrombotic Thrombocytopenic Purpura. Experience Of The French Thrombotic Microangiopathies Reference Center

Blood ◽

10.1182/blood.v122.21.448.448 ◽

2013 ◽

Vol 122 (21) ◽

pp. 448-448

Author(s):

Miguel HIE ◽

Julie Gay ◽

Lionel Galicier ◽

Francois Provot ◽

Sandrine Malot ◽

...

Keyword(s):

Thrombotic Thrombocytopenic Purpura ◽

Median Number ◽

Continuous Variables ◽

Adamts13 Activity ◽

Thrombocytopenic Purpura ◽

History Of ◽

Adamts13 Deficiency ◽

Group 2 ◽

Group 1

Context Acquired thrombotic thrombocytopenic purpura (TTP) results from a severe, antibody-mediated, deficiency in the von Willebrand factor-cleaving protease ADAMTS13. Rituximab is increasingly used in this indication in patients with a suboptimal response to plasma exchange. When severe acquired ADAMTS13 deficiency persists during remission, the estimated incidence rate is of 0.4/year. So far, it is still controversial whether preemptive rituximab efficiently prevents relapses in these patients. Patients and methods We defined two groups of patients with a history of acquired TTP who displayed a persistent severe ADAMTS13 deficiency during remission. Patients of group 1 were treated with preemptive infusions of rituximab. Patients of group 2 were managed in centers in which preemptive rituximab infusions were not the standard of care. The relapse incidence was evaluated and compared between both groups. Patients were treated according to National recommendations and enrolled from 12 French centers during a 12-year period. Patients were explored for ADAMTS13 activity and peripheral B-cell count every 3 months. Only patients with a > 12-month follow-up after rituximab administration are reported here. Median (25th - 75th percentile) was determined for all continuous variables. Wilcoxon’s test was used to compare continuous variables and the chi-square test or Fisher’s exact test to compare binary data. Relapse-free survival was compared between both groups using the Kaplan-Meier estimator with the corresponding 95% confidence interval. Results Forty-eight patients (20.6%) with a history of acquired TTP displayed a persistent severe ADAMTS13 deficiency on remission or experienced a subsequent severe ADAMTS13 deficiency (24 cases each) after a median follow-up of 17 months (12-29 months). Anti-ADAMTS13 antibodies concentration was 44 U/mL (24-59 U/mL). Thirty patients received preemptive infusions of rituximab (group 1), whereas 18 others had no therapeutical intervention (group 2). In group 1, 16 patients experienced a past history of TTP with a median number of 2 (1-3) episodes, corresponding to a relapse incidence of 0.22 (0-0.57)/year. Rituximab infusions were performed 14.5 months (6.5-27.4 months) after the last TTP episode. A median number of 4 (1-4) rituximab infusions were performed. The median follow-up between the first preemptive infusion of rituximab and the last ADAMTS13 evaluation is of 36 months (24-65 months). After preemptive rituximab administration, only 3 patients experienced a clinical relapse (0 [0] episode/year), corresponding to a significant reduction in the relapse incidence (P < .01). ADAMTS13 activity was 58.5% (30.5%-86.3%). Three months after the first rituximab infusion, ADAMTS13 activity was 46% (30-68); it further increased until the 12th month, and subsequently decreased. Accordingly, B-cell lymphocytes remained undetectable until the 6th month, and progressively increased at the 9th month to reach normal values at the 18th month. Nine patients (30%) required one (5 cases), two (2 cases), three (1 case) or ten (1 case) additional courses of rituximab for a further decrease or a persistent undetectable ADAMTS13 activity, which allowed to maintain a detectable ADAMTS13 activity in all but one patients. The time between two consecutive courses of rituximab was 26 months (5-59 months). At the end of follow-up, ADAMTS13 activity remained normal in 18 patients; 10 patients had a moderate ADAMTS13 deficiency, and 2 patients had a persistently undetectable ADAMTS13 activity. In four patients (13%), rituximab alone failed to increase durably ADAMTS13 activity, which required additional immunosuppressive drugs. In group 2, 14 patients relapsed after a 66-month follow-up (36-105 months), corresponding to a higher relapse incidence than in patients who received preemptive infusions of rituximab (0.23 [0.1-0.46] relapse/year, P<.01). Moreover, 2 patients died of TTP in group 2, whereas no fatal outcome was recorded in group 1. Relapse free survival over time was significantly longer in group 1 (Log-rank test: P = .049). Five patients experienced adverse effects including benign infections in 2 cases. Conclusion Rituximab efficiently prevents TTP relapses in most patients with a persistent acquired ADAMTS13 deficiency, with acceptable side effects. Disclosures: Off Label Use: Rituximab Rituximab may prevent relapses in acquired thrombotic thrombocytopenic purpura.

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An enzyme immunoassay of ADAMTS13 distinguishes patients with thrombotic thrombocytopenic purpura from normal individuals and carriers of ADAMTS13 mutations

Thrombosis and Haemostasis ◽

10.1160/th03-11-0675 ◽

2004 ◽

Vol 91 (04) ◽

pp. 806-811 ◽

Cited By ~ 45

Author(s):

Wenhua Zhou ◽

Han-Mou Tsai

Keyword(s):

Fusion Protein ◽

Enzyme Immunoassay ◽

Thrombotic Thrombocytopenic Purpura ◽

Activity Level ◽

Dependent Manner ◽

Plasma Samples ◽

Adamts13 Activity ◽

Thrombocytopenic Purpura ◽

Normal Plasma ◽

Normal Individuals

SummaryRecent studies demonstrate that assay of ADAMTS13, a circulating zinc metalloprotease that cleaves von Willebrand factor (VWF) at the Y1605-M1606 bond, is an important tool in the diagnosis of thrombotic thrombocytopenic purpura (TTP). In order to develop a method that could be adapted for general use, we describe an enzyme immunoassay (EIA)-based method for measuring the activity of ADAMTS13 in patient plasma samples. A monomeric peptide consisting of the amino acid residues D1596-R1668 of VWF was produced that spanned the ADAMTS13 cleavage site and was franked by glutathione s-transferase (GST) and a 6His sequences at the amino and carboxyl termini respectively. When probed with either anti-GST or anti-6His, the VWF fragment appeared as a 38.1-kDa band. After incubation with normal plasma, the VWF fragment was replaced by a 30.4-kDa band, which was recognized by antiGST but not by anti-6His, consistent with the expected cleavage at the Y1605-M1606 bond. EDTA or plasma samples from patients with TTP inhibited this cleavage. After incubation with normal plasma, the VWF fusion protein immobilized onto antiGST coated microtiter plate wells lost its anti-6His binding activity in a timeand plasma concentration-dependent manner. By using this EIA, the ADAMTS13 activity level was less than 0.12 U/mL in patients with acquired or hereditary TTP, distinguishing these patients from normal individuals or carriers of one copy of mutant ADAMTS13 allele. These results suggest the EIA method based on the VWF fusion protein is a simple but promising alternative for measuring ADAMTS13 activity.

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Inhibition of ADAMTS13 Activity By Human Neutrophil Peptide 1 (HNP-1): Potential Link Between Inflammation, Onset of Thrombotic Thrombocytopenic Purpura, and Other Thrombosis

Blood ◽

10.1182/blood.v124.21.599.599 ◽

2014 ◽

Vol 124 (21) ◽

pp. 599-599 ◽

Cited By ~ 1

Author(s):

Jialing Bao ◽

Khalil Bdeir ◽

Don L. Siegel ◽

Douglas B. Cines ◽

X. Long Zheng

Keyword(s):

Thrombotic Thrombocytopenic Purpura ◽

Human Neutrophil ◽

Conflicts Of Interest ◽

Human Monoclonal Antibody ◽

Amino Acid Sequences ◽

Dependent Manner ◽

Adamts13 Activity ◽

Single Chain ◽

Concentration Dependent Manner ◽

Thrombocytopenic Purpura

Abstract Thrombotic thrombocytopenic purpura (TTP) is a potentially fatal syndrome associated with severe deficiency of plasma ADAMTS13 activity resulting from either mutations or autoantibodies. However, patients with severe ADAMTS13 deficiency do not always develop TTP. Rather, a trigger, such as infection or inflammation, often precedes the onset of the TTP syndrome. We hypothesized that antimicrobial human neutrophil peptides 1-3 (HNPα1-3) or α-defensins, the most abundant proteins in the granules of neutrophils, which are released at site of inflammation, activate platelets, and inhibit fibrinolysis, might help to initiate TTP. This question arose because we noted that the amino acid sequences of HNPα1-3, which are nearly identical except for one residue at the N-terminus, all contain a motif (RRY) similar to exosite 3 (659RRYGEEY665) in the spacer domain of ADAMTS13 (Fig. 1) that was shown to be critical for recognition of von Willebrand factor (VWF). Here, we found that both purified and synthetic HNPα1 bind to FRETS-VWF73 and plasma-derived VWF and inhibit proteolytic cleavage of these substrates in a concentration-dependent manner. At the final concentrations of 10 micro mol/L and 150 micro mol/L, HNPα1 completely abolished the cleavage of FRETS-VWF73 (IC50=3.5 micro mol/L) (Fig. 2) and VWF (IC50=75 micro mol/L) (not shown), respectively. Such concentrations are readily attained locally after systemic infection. Deletion or alanine substitution within the RRY motif of HNPα1 completely abolished its ability to inhibit ADAMTS13 activity assessed by FRETS-VWF73 and VWF multimer analysis. This suggests that an interaction of the RRY motif in HNPα1 with the central A2 domain of VWF is required to mediate its inhibition. In support of this hypothesis, HNPα1 interacts with a human monoclonal antibody against ADAMTS13 scFv (the single chain fragment of variable region) designated 4-20, but not scFv3-1, both isolated by phage display from patients with acquired autoimmune TTP. Hydrogen-deuterium exchange mass spectrometry has shown that the binding site for scFv4-20, but not scFv3-1, contains the RRY sequence. These results suggest that HNPα1-3 released from neutrophils following infection or inflammation may inhibit residual plasma ADAMTS13 activity in vivo similar to anti-ADAMTS13 autoantibodies by interfering with its interaction with VWF, thereby triggering the onset of hereditary and acquired autoimmune TTP. Our findings suggest a potential novel link between systemic inflammation and the pathogenesis of TTP and possibility other thrombotic sequelae. Figure 2 Figure 2. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

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Relapsing Thrombotic Thrombocytopenic Purpura: A Single Center Experience

Blood ◽

10.1182/blood.v128.22.3732.3732 ◽

2016 ◽

Vol 128 (22) ◽

pp. 3732-3732

Author(s):

Arielle L Heeke ◽

Craig M. Kessler ◽

Catherine Broome

Keyword(s):

Disease Control ◽

Thrombotic Thrombocytopenic Purpura ◽

Research Funding ◽

Activity Level ◽

High Dose ◽

Adamts13 Activity ◽

Thrombocytopenic Purpura ◽

The Mean ◽

Term Management

Abstract Thrombotic thrombocytopenic purpura (TTP) is due to a severe deficiency of the von Willebrand factor (vWF) cleaving serine metalloprotease ADAMTS13 and is most commonly diagnosed in adults due to autoantibodies against ADAMTS13. Standard therapy includes plasma exchange (PEX) until platelet counts normalize plus concurrent high dose corticosteroids. In refractory cases, weekly pulse Rituximab for 4 doses is often added. Successful long-term management of relapsing patients beyond these treatments is unclear, in part because the mechanisms for relapsing TTP are unknown. Dysfunctional immunoregulatory systems likely play a role in relapsing disease. Several case series have described disease control following bortezomib therapy (Patriquin 2016). Other immunomodulators including complement pathway and tyrosine kinase inhibitors may prove to offer benefit. Further, supplementing PEX with N-acetylcysteine (Rottenstreich 2016) & Caplacizumab (anti-vWF humanized immunoglobulin) (Peyvandi 2016) has shown promising preliminary clinical results when used to treat an acute episode. Effects on relapse rates with these treatments have not been fully evaluated. Eight cases of relapsing TTP were identified at MedStar Georgetown University Hospital May 2004 to July 2016. Relapsing TTP was defined as recurrent episode(s) of thrombocytopenia, microangiopathic hemolysis, and confirmed ADAMTS13 activity levels <10% following remission from the initial TTP episode. Retrospective chart review was completed to evaluate demographic and clinicopathologic features, laboratories and treatment at relapse(s), and clinical outcomes. In our 8 patient cohort, 75% are female (6/8), 62.5% are African American (AA) (5/8), and the mean age at initial TTP diagnosis is 35.38 (range 16-67). The mean number of relapses is 3.38 (range 2-9) with a mean platelet nadir of 45,000/mcL. All patients remain alive. Two are ANA positive, 1 with known systemic lupus erythematosus (SLE) and 1 with suspected SLE. None are HIV positive, and none endorse a family history of TTP. Four identified infections as triggers for their TTP, 1 patient developed TTP during pregnancy and hormonal fertility treatments, and 3 had no identifiable triggers. All had an increased titer of ADAMTS13 inhibitor (Bethesda titer range 0.7 - >8) at the time of relapse(s). Normalization of ADAMTS13 activity was confirmed in most following treatment (n=6), with a mean ADAMTS13 activity level between relapses of 50.5% (range 32-88%). At the time of each relapse, all patients underwent daily PEX with fresh frozen plasma plus high dose corticosteroids for at least 5 days (range 5-21 days), with some requiring gradual PEX weaning over 1-4 weeks and steroid tapering over months based on lab parameters. Two relapsed quickly after PEX discontinuation, both in the setting of systemic illness (lupus flare, cholecystitis). Sequelae of TTP (neurologic, renal, hematologic anomalies) resolved with treatment. All patients received Rituximab therapy during the 1st or 2nd relapse. For the majority (87.5%, 7/8), this intervention did not lead to long-term remission, although 100% (2/2) who transitioned to prophylactic bolus Rituximab every 6 months post splenectomy achieved long-term disease control. It is difficult to distinguish whether remission resulted from maintenance Rituximab, the splenectomy, or a combination of the two. Patients who underwent splenectomy were vaccinated and have not had difficulty with infections or thrombosis. In conclusion, our cohort of patients with relapsing TTP all had documented ADAMTS13 inhibitors and acutely responded to daily PEX (most requiring PEX wean based on lab parameters) plus high dose corticosteroids. Although Rituximab therapy during initial relapse did not offer a high percentage of long-term remissions, the addition of prophylactic Rituximab every 6 months post splenectomy has achieved long-term control in 2 patients. In our cohort the majority are AA, suggesting genetic susceptibility. HLA/immune transcript levels and ribosomal gene signatures may correlate with TTP disease activity and risk for relapse (Edgar 2015), and could be used to identify high-risk patients in need of more intensive therapy. Given the complexity and severity of this disease, there is an ongoing need for evaluation of relapsing TTP and best strategies for long-term management. Disclosures Kessler: Octapharma: Consultancy, Research Funding; Novo Nordisk: Consultancy, Research Funding; Grifols: Consultancy; Genentech: Consultancy, Research Funding; Biogen: Consultancy; Pfizer: Consultancy; Bayer: Consultancy, Research Funding; Baxalta: Consultancy, Research Funding; LFB: Other: Member of DSMB. Broome:True North Therapeutics: Honoraria; Alexion Pharmaceuricals: Honoraria.

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Absolute Immature Platelet Counts Suggest Platelet Production Suppression during Complicated Relapsing Thrombotic Thrombocytopenic Purpura

Acta Haematologica ◽

10.1159/000510913 ◽

2020 ◽

pp. 1-5 ◽

Cited By ~ 1

Author(s):

Sirisha Kundrapu ◽

Hollie M. Reeves ◽

Robert W. Maitta

Keyword(s):

Mycophenolate Mofetil ◽

Maintenance Therapy ◽

Thrombotic Thrombocytopenic Purpura ◽

Adamts13 Activity ◽

Thrombocytopenic Purpura ◽

Early Therapy ◽

Platelet Production ◽

Platelet Counts ◽

Initial Improvement

Absolute immature platelet counts (A-IPC) aid in diagnosis and treatment follow-up in thrombotic thrombocytopenic purpura (TTP). A-IPC was used to follow a patient on mycophenolate mofetil (MMF) maintenance therapy treated with a prolonged therapeutic plasma exchange (TPE) regimen for relapsing TTP. On admission, the platelet (PLT) count was 95 × 109/L declining to 14 × 109/L in 5 days. Daily TPE was initiated for suspected TTP, and MMF was discontinued. A-IPC and PLT count were 1 × 109/L and 14 × 109/L, respectively, prior to first TPE. A-IPC improved to 3.2 × 109/L with 1 TPE, and on day 5, A-IPC and PLT count were 7.5 × 109/L and 218 × 109/L, respectively. On day 6, A-IPC and PLT count decreased to 4.8 × 109/L and 132 × 109/L further worsening to 0.4 × 109/L and 13 × 109/L, respectively. ADAMTS13 activity remained <5% with an inhibitor; counts did not recover. Initial improvement followed by rapidly declining A-IPC despite therapy suggested production suppression. In TTP, A-IPC may aid in establishing early therapy effects over PLT production.

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