Incidence of acquired thrombotic thrombocytopenic purpura in Germany: a hospital level study

Management of immune thrombotic thrombocytopenic purpura without therapeutic plasma exchange

ABSTRACT

Immune thrombotic thrombocytopenic purpura (iTTP) is a rare, life-threatening autoimmune disorder caused by a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13 (ADAMTS13) deficiency. Caplacizumab, an anti-von Willebrand factor nanobody, is approved for iTTP treatment, reducing the need for therapeutic plasma exchange (TPE) and improving platelet count recovery and survival. We conducted a retrospective study on 42 acute iTTP cases in Austria and Germany, treated with a modified regimen aimed at avoiding TPE if platelet count increased after the first caplacizumab dose. Baseline characteristics and patient outcomes were compared with a control group of 59 patients with iTTP receiving frontline treatment with TPE, caplacizumab, and immunosuppression. The main outcome was the time to platelet count normalization. Secondary outcomes included clinical response, exacerbation, refractory iTTP, iTTP-related deaths, and the time to platelet count doubling. The median time to platelet count normalization was similar between the 2 cohorts (3 and 4 days; P = .31). There were no significant differences in clinical response, exacerbations, refractoriness, iTTP-related deaths, or time to platelet count doubling, reflecting the short-term treatment response. Four patients did not respond to the first caplacizumab dose, and TPE was subsequently initiated. Cytomegalovirus infection, HIV/hepatitis B virus coinfection, an ovarian teratoma with associated antiplatelet antibodies, and multiple platelet transfusions before the correct diagnosis may have impeded the immediate treatment response in these patients. In conclusion, caplacizumab and immunosuppression alone, without TPE, rapidly controlled thrombotic microangiopathy and achieved a sustained clinical response in iTTP. Our study provides a basis for TPE-free iTTP management in experienced centers via shared decision-making between patients and treating physicians.

A Systematic Review of the Epidemiology and Disease Burden of Congenital and Immune-Mediated Thrombotic Thrombocytopenic Purpura

Congenital (cTTP) and immune-mediated (iTTP) thrombotic thrombocytopenic purpura are serious and rare clotting disorders resulting from a deficiency in the ADAMTS13 enzyme. A systematic review was conducted using the Ovid® MEDLINE & Embase databases to synthesize the epidemiology and burden of cTTP and iTTP worldwide (from January 1, 2010, to February 6, 2020, with an update that covered the period January 1, 2020-February 11, 2022). Outcomes of interest were incidence and prevalence of TTP, incidence of acute episodes, mortality, burden of illness (eg complications, healthcare utilization, patient-reported outcomes) and disease management. A total of 221 eligible observational studies were included. The incidence rate of acute episodes ranged from 0.19-0.35 person-years in adult patients with cTTP, and 1.81-3.93 per million persons per year for iTTP in the general population. Triggers of acute episodes were similar for cTTP and iTTP, with pregnancy and infection the most commonly observed. Exacerbation in patients with iTTP varied widely, ranging from 2.4-63.1%. All-cause mortality was observed in 0-13.4% of patients with cTTP, across studies and follow-up periods, and in 1.1% (median follow-up: 0.4 years) to 18.8% (1 year) of patients with iTTP during acute episodes. Cardiovascular, renal, and neurological disease were common complications. TTP also led to work disturbances, feelings of anxiety and depression, and general activity impairment. TTP treatment regimens used were generally reflective of current treatment guidelines. The evidence identified describes a high patient burden, highlighting the need for effective treatment regimens leading to improvements in outcomes. Considerable evidence gaps exist, particularly for disease epidemiology, patient-reported outcomes, costs of disease management, and associated healthcare resource utilization. This review may help increase disease awareness and highlights the need for additional real-world studies, particularly in geographical regions outside the United States and Western Europe.

Real-World Data Analysis of Patients Affected by Immune-Mediated Thrombotic Thrombocytopenic Purpura in Italy

Background: The therapeutic management of immune-mediated thrombotic thrombocytopenic purpura (iTTP) has recently benefited from the introduction of caplacizumab, an agent directed at the inhibition of platelet aggregation. This real-world analysis investigated the epidemiology and the demographic and clinical characteristics of iTTP patients in Italy before and after caplacizumab introduction in 2020. Methods: Hospitalized adults with iTTP were included using the administrative databases of healthcare entities covering 17 million residents. Epidemiological estimates of iTTP considered the 3-year period before and after caplacizumab introduction. After stratification by treatment with or without caplacizumab, iTTP patients were characterized for their baseline features. Results: The annual incidence before and after 2020 was estimated in the range of 4.3-5.8 cases/million and 3.6-4.6 cases/million, respectively. From 2018 to 2022, 393 patients with iTTP were included, and 42 of them were treated with caplacizumab. Caplacizumab-treated patients showed better clinical outcomes, with tendentially shorter hospital stays and lower mortality rates (no treated patients died at either 1 month or 3 months after caplacizumab treatment initiation, compared to 10.5% and 11.1% mortality rates at 1 and 3 months, respectively, of the untreated ones). Conclusions: These findings may suggest that caplacizumab advent provided clinical and survival benefits for patients with iTTP.

Immune thrombotic thrombocytopenic purpura in older patients: Results from the Spanish TTP Registry (REPTT)

Immune thrombotic thrombocytopenic purpura (iTTP) is an ultra-rare disease that seldom occurs in the elderly. Few reports have studied the clinical course of iTTP in older patients. In this study, we have analysed the clinical characteristics at presentation and response to therapy in a series of 44 patients with iTTP ≥60 years at diagnosis from the Spanish TTP Registry and compared them with 209 patients with <60 years at diagnosis from the same Registry. Similar symptoms and laboratory results were described in both groups, except for a higher incidence of renal dysfunction among older patients (23% vs. 43.1%; p = 0.008). Front-line treatment in patients ≥60 years was like that administered in younger patients. Also, no evidence of a difference in clinical response and overall survival was seen in both groups. Of note, 14 and 25 patients ≥60 years received treatment with caplacizumab and rituximab, respectively, showing a favourable safety and efficacy profile, like that observed in patients <60 years.

Spanish registry of thrombotic thrombocytopenic purpura (REPTT): Data evidence and new developments

Immuno Thrombotic thrombocytopenic purpura (iTTP) is a rare and potentially fatal disorder characterized by systemic microvascular thrombosis because of a severe deficiency of ADAMTS13. It is difficult to generate knowledge about TTP because of its low incidence and the lack of clinical trials. Most of the evidence on diagnosis, treatment, and prognosis has been generated from real-world data registries. In 2004, the Spanish Apheresis Group (GEA) implemented the Spanish registry of TTP (REPTT) with 438 patients suffering 684 acute episodes in 53 hospitals up to January 2022. REPTT has studied several aspects of TTP in Spain. The iTTP incidence in Spain our country is 2.67 (95 % CI 1.90-3.45) and the prevalence is 21.44 (95 % CI % 19.10-23.73) patients per million inhabitants. The refractoriness incidence is 4.8 % and exacerbation incidence was 8.4 %, with a median of follow-up of 131.5 months (IQR: 14-178 months). In a 2018 review, the mortality in the first episode due to TTP was 7.8 %. We have also found that de novo episodes require fewer PEX procedures than relapses. Since June 2023, REPTT will involve Spain and Portugal, with a recommended sampling protocol and new variables to improve the neurological, vascular and quality of life evaluation of these patients. The main strength of this project will be the involvement of a combined population of more than 57 million inhabitants, which implies an annual incidence of close to 180 acute episodes per year. This will allow us to provide better answers to questions like treatment efficacy, associated morbidity and mortality, and the possible neurocognitive and cardiac sequelae.

An update on the pathogenesis and diagnosis of thrombotic thrombocytopenic purpura

INTRODUCTION

Severe ADAMTS13 deficiency defines thrombotic thrombocytopenic purpura (TTP). ADAMTS13 is responsible for VWF cleavage. In the absence of this enzyme, widespread thrombi formation occurs, causing microangiopathic anemia and thrombocytopenia and leading to ischemic organ injury. Understanding ADAMTS13 function is crucial to diagnose and manage TTP, both in the immune and hereditary forms.

AREAS COVERED

The role of ADAMTS13 in coagulation homeostasis and the consequences of its deficiency are detailed. Other factors that modulate the consequences of ADAMTS13 deficiency are explained, such as complement system activation, genetic predisposition, or the presence of an inflammatory status. Clinical suspicion of TTP is crucial to start prompt treatment and avoid mortality and sequelae. Available techniques to diagnose this deficiency and detect autoantibodies or gene mutations are presented, as they have become faster and more available in recent years.

EXPERT OPINION

A better knowledge of TTP pathophysiology is leading to an improvement in diagnosis and follow-up, as well as a customized treatment in patients with TTP. This scenario is necessary to define the role of new targeted therapies already available or coming soon and the need to better diagnose and monitor at the molecular level the evolution of the disease.

Real-world effectiveness of caplacizumab vs the standard of care in immune thrombotic thrombocytopenic purpura

Immune thrombotic thrombocytopenic purpura (iTTP) is a thrombotic microangiopathy caused by anti-ADAMTS13 antibodies. Caplacizumab is approved for adults with an acute episode of iTTP in conjunction with plasma exchange (PEX) and immunosuppression. The objective of this study was to analyze and compare the safety and efficacy of caplacizumab vs the standard of care and assess the effect of the concomitant use of rituximab. A retrospective study from the Spanish TTP Registry of patients treated with caplacizumab vs those who did not receive it was conducted. A total of 155 patients with iTTP (77 caplacizumab, 78 no caplacizumab) were included. Patients initially treated with caplacizumab had fewer exacerbations (4.5% vs 20.5%; P < .05) and less refractoriness (4.5% vs 14.1%; P < .05) than those who were not treated. Time to clinical response was shorter when caplacizumab was used as initial treatment vs caplacizumab used after refractoriness or exacerbation. The multivariate analysis showed that its use in the first 3 days after PEX was associated with a lower number of PEX (odds ratio, 7.5; CI, 2.3-12.7; P < .05) and days of hospitalization (odds ratio, 11.2; CI, 5.6-16.9; P < .001) compared with standard therapy. There was no difference in time to clinical remission in patients treated with caplacizumab compared with the use of rituximab. No severe adverse event was described in the caplacizumab group. In summary, caplacizumab reduced exacerbations and refractoriness compared with standard of care regimens. When administered within the first 3 days after PEX, it also provided a faster clinical response, reducing hospitalization time and the need for PEX.

Incidence of thrombotic microangiopathies in Quebec: insight from a laboratory centralizing ADAMTS-13 testing

BACKGROUND

Thrombotic microangiopathies (TMA) are serious medical conditions requiring a prompt diagnosis to adapt treatment. The determination of ADAMTS-13 activity enables discriminating thrombotic thrombocytopenic purpura (TTP) from other forms of TMA. The purpose of this study was to provide an estimate of the incidence of TTP and TMA in the Canadian Quebec province using data collected from a laboratory centralizing ADAMTS-13 testing for the whole province.

RESULTS

From 2012 to 2019, 846 patients were evaluated for plasma ADAMTS-13 activity due to a suspicion of TMA. TTP was identified in 147 patients. Of these, 118 patients with a median age of 51.5 years and a male-female ratio of 1:1.4 had their first episode of TTP during the study period. The number of ADAMTS-13 tests performed and the number of patients with suspected TMA increased annually by 19% and 21% respectively. While the incidence of non-TTP TMA increased annually, that for TTP remained unchanged. This averaged 10.2 (95% CI 5.9-14.4) per million persons per year for suspected non-TTP TMA and 1.8 (95% CI 1.3-2.4) for confirmed TTP. The incidence rate of TMA other than TTP was higher in the age group 70-79 years (21.8; 95% CI 5.4-38.1) for females and in the age group 80-89 years (24.4; 95% CI 7.2-41.7) for males compared to other age groups. The incidence rate of TTP was higher in the age group 40-49 years (4.0; 95% CI 2.0-5.9) for women and in the age group 60-69 years (3.4; 95% CI 1.1-5.6) for men compared to other age groups.

CONCLUSION

The analysis of centralized data measuring ADAMTS-13 activity allowed us to adequately establish the incidence rate and demographic characteristics of TMA, particularly TTP, in Quebec. TTP incidence remained stable while suspected non-TTP TMA steadily increased from 2012 to 2019.

Epidemiology, treatment patterns, clinical outcomes, and disease burden among patients with immune-mediated thrombotic thrombocytopenic purpura in the United States

Background

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a life-threatening thrombotic microangiopathy. Due to its rarity, epidemiology and real-world outcomes data are scarce.

Objectives

The aim was to assess epidemiology, treatment patterns, clinical outcomes, and disease burden in patients with iTTP in the United States.

Methods

This longitudinal, retrospective observational study of the Optum-Humedica database included patients with an iTTP diagnosis (≥1 documented ADAMTS13 activity less than 10% or one or more iTTP episodes) from January 2007 to December 2019.

Results

Of 666 patients with an iTTP diagnosis between October 2015 and December 2019, 302 (45%) had one or more iTTP episodes. The pooled annual incidence of documented iTTP during this period was 3.43/million, and the annual incidence of one or more iTTP episodes was 1.81/million. Patients with one or more iTTP episodes received a median of six therapeutic plasma exchange (TPE) sessions per episode; 86% received corticosteroids, and 59% received rituximab. Exacerbations occurred in 17% (52/302) and relapse in 11% (34/302); 34% (103/302) had one or more thromboembolic events. Mortality rates during the study period were 25% (167/666) among all patients with iTTP diagnosis, and 14% (41/302) among patients with one or more iTTP episodes. In the assessment of disease burden (January 2007 to September 2019), patients in the iTTP cohort (n = 514) presented with a mean of 14 comorbidities, compared with 3 in a matched non-iTTP cohort (n = 2570). In a cluster analysis, duration of iTTP episode and mortality rate were greater in older versus younger patients.

Conclusions

Despite treatment with TPE and immunosuppressants, patients with iTTP have high risk of morbidity and mortality, demonstrating the need for more effective therapies.

A Race against the Clock: A Case Report and Literature Review Concerning the Importance of ADAMTS13 Testing in Diagnosis and Management of Thrombotic Thrombocytopenic Purpura during Pregnancy

Thrombocytopenic purpura (TTP) is a rare, potentially fatal pathology characterized by microangiopathic thrombotic syndrome and caused by an acute protease deficiency of von Willebrand factor, ADAMTS13. Moreover, ADAMTS13 deficiency promotes microthrombosis led by the persistence of ultra-large VWF multimers in the blood circulation. According to the few studies involving pregnant participants, the heterogeneity of manifestations has made this pathology difficult to diagnose, with an unexpected occurrence and increased risk of maternal and fetal morbidity and mortality. We reported on the case of a 28-year-old pregnant woman with an obstetric score of G2P0 who presented to the obstetrics and gynecology department of our clinic with the complaint of minimal vaginal bleeding. The evolution of our case was severe and life-threatening, a “race against the clock”, with our goal being to emphasize the importance and difficulty of diagnosing TTP in the absence of specific symptomatology. We faced a lack of technological support for a correct and complete diagnosis, and the first manifestation of this disease was the intrauterine death of the fetus. After completing all the necessary procedures, the placental tissue was sent for further histopathological evaluation. We highlighted the importance of monitoring ADAMTS13 for relapses monthly, with prophylaxis being essential for maternal and fetal mortality and morbidity.

Lombardy diagnostic and therapeutic network of thrombotic microangiopathy

Background

Thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening thrombotic microangiopathy (TMA) requiring urgent treatment. Standardization of its diagnosis and optimal management is challenging. This study aimed to evaluate the role of centralized, rapid testing of ADAMTS13 in patients experiencing acute TMAs requiring plasma-exchange (PEX) and to estimate the incidence of TTP in a large Italian Region.

Methods

We perfomed a cohort study in the frame of the project “Set-up of a Lombardy network for the study and treatment of patients undergoing apheresis”, including 11 transfusion centers in the Region. Consecutive patients referred from 2014 to 2016 with acute TMAs requiring PEX were enrolled. Centralized ADAMTS13 activity testing was performed at the Milan Hemophilia and Thrombosis Center within 24 h.

Results

Forty-three TMA patients (44 events) were enrolled, of whom 35 (81%) had severe ADAMTS13 deficiency. Patients with severe ADAMTS13 deficiency were younger, mainly women, with a higher prevalence of autoimmune disorders and a lower prevalence of cancer. Clinical and laboratory characteristics of patients with and without severe ADAMTS13 deficiency largely overlapped, with a lower platelet count being the only baseline marker that significantly differed between the two patient groups (ADAMTS13 activity < 10% vs ≥ 10%: median difference of -27 × 10⁹/l, 95% CI − 37 to − 3). PEX treatment was initiated in all patients, but soon discontinued in cases without severe ADAMTS13 deficiency. In this group, the mortality rate was higher and no episode exacerbations or relapses within 6 months occured. The estimated average annual incidence of acute acquired TTP events was 1.17 [0.78–1.55] per million people.

Conclusions

Severe ADAMTS13 deficiency distinguished two groups of patients with largely overlapping clinical features but different treatment and disease course. This study provides a feasible model implemented in a large Italian region for the practical clinical approach to TMAs and underlines the importance of urgent ADAMTS13 activity testing for an accurate differential diagnosis and therapeutic approach.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02400-y.

Cost-consequence analysis of diagnosis and early treatment of acquired thrombotic thrombocytopenic purpura in Colombia

INTRODUCTION

The objective of the study was to evaluate the costs and benefits of early identification and treatment (within 24 hours of admission) of patients with aTTP in Colombia.

METHODS

A cost-consequence analysis was conducted to evaluate the costs and health outcomes of diagnosis and early treament versus no treatment (scenario 1) and late treatment (scenario 2) in a hypothetical cohort of 100 patients with aTTP. The analysis perspective was that of the third-party payer.

RESULTS

In scenario 1, he total cost of early treatment was USD$515,157 compared to USD$293,265 for no treatment. Early treatment avoided 65 deaths in the hypothetical cohort. The cost per death avoided was USD$3,414. In scenario 2, the cost of early treatment was USD$935,507 compared to USD$809,103 in the late start of treatment. By treating patients early, 33 deaths were avoided, 23 patients were estimated to be alive without exacerbations and 16 without relapses. The cost per death avoided was USD$3,879 and the cost per patient alive without exacerbations and relapses was USD$5,611 and USD$7,858, respectively.

CONCLUSIONS

The early identification and treatment of patients with aTTP are associated with benefits in survival and recurrence-free survival, and an incremental cost in the process of care compared to no treatment or late treatment.

First diagnosis of thrombotic thrombocytopenic purpura after SARS-CoV-2 vaccine - case report

Background

We report a case of a 25-year-old male patient, who developed acquired thrombotic thrombocytopenic purpura (aTTP) after receiving a first dose of mRNA-based SARS-CoV-2 vaccine Spikevax (mRNA-1273, Moderna Biotech, USA). While this is the first case in literature describing a case of aTTP after receiving the Spikevax vaccine, there are two other cases after mRNA-based Covid-19 vaccine and two after adenoviral SARS-CoV-2 vaccine.

Case presentation

The patient presented with persisting malaise, fever, headache, word-finding difficulties, nausea, vomiting, petechial bleeding, and hematuria 13 days after receiving a first dose of vaccination. Laboratory testing showed low platelet count, Coombs-negative hemolytic anemia, and mild acute kidney injury. We excluded vaccine induced immune thrombotic thrombocytopenia (VITT) as another important differential diagnosis and the final diagnosis was established after ADAMTS-13 (A Disintegrin And Metalloproteinase with a ThromboSpondin type 1 motif, member 13) activity was found to be < 1% (reference range > 40%) and ADAMTS-13 antibodies being 72.2 IU/L (reference range < 12 IU/L).

We initiated empiric therapy of plasmapheresis and corticosteroids on admission and started caplacizumab the day after. The patient’s thrombocyte count normalized 3 days after admission, hemolysis and acute kidney injury resolved after 2 weeks. The patient received 2 doses of rituximab (1 g each) after the diagnosis of immune TTP was established. One month after the initial presentation, the patient is in good overall condition, but still receives daily caplacizumab due to ADAMTS-13 activity of < 1%.

Conclusions

Low platelet count after vaccination against SARS-CoV-2 has gained attraction after vaccine-induced immune thrombotic thrombocytopenia (VITT) has been described as a rare but severe complication of adenoviral-based vaccines. Thrombotic thrombocytopenic purpura (TTP) is an important differential diagnosis, but there are only few reports of TTP following SARS-CoV-2 vaccination. Despite pathophysiological and clinical differences of both entities, diagnostic uncertainty can result in the acute setting, since they share main symptoms such as headache and neurological alterations in addition to thrombocytopenia. In difference to other cases reported, this patient developed first symptoms of TTP as early as 4 days after vaccination, which suggests that vaccination merely acted as trigger for occult TTP, instead of truly inducing an autoimmunological process.

Acute myocardial infarction and extensive systemic thrombosis in thrombotic thrombocytopenic purpura: A case report and review of literature

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy characterized by the pentad of hemolytic anemia, fever, thrombocytopenia, renal failure, and neurological dysfunction. The formation of microthrombi in the arterioles and capillaries of various organs is one of the main pathophysiological mechanisms. Clinical manifestations of cardiac involvement in TTP patients are variable. Acute myocardial infarction has been reported as a complication with TTP as the secondary thrombotic event. Its emergence as the initial thrombotic event is extremely rare.

CASE SUMMARY

A 49-year-old previously healthy man was admitted for fever, typical angina chest pain 3 d prior to presentation, and newly onset left lower limb pain. The electrocardiogram illustrated ST-elevation acute myocardial infarction of the antero-lateral wall of the left ventricle. Transthoracic echocardiography depicted two large thrombi at the apex of the left ventricle and moderately reduced ejection fraction (40%). Venous Doppler ultrasound showed occlusion of the left popliteal artery. Laboratory tests showed severe thrombocytopenia, mild hemolytic anemia, elevated D-dimers, and high troponin and creatine kinase-MB. Abdominal computed tomography revealed other thrombotic sites (superior mesenteric artery, posterior aortic wall, spleen and renal infarction, and ileum necrosis). He was immediately started on steroids and addressed to surgery for acute abdominal pain. After an initial stabilization of the hematological deficit, he went into general surgery for resection of the necrotic ileum but died soon after the intervention due to multiple organ failure.

CONCLUSION

Cardiac involvement in TTP patients is common, challenging and more often fatal, especially when other thrombotic complications coexist.

First report of a de novo iTTP episode associated with an mRNA-based anti-COVID-19 vaccination

Thrombotic thrombocytopenic purpura (TTP) is a rare but potentially life-threatening thrombotic microangiopathy, characterized by disseminated thrombus formation in the microvasculature, causing severe organ failure. Immune-mediated TTP (iTTP) is occasionally described after vaccination, especially against viral agents. We report a case of a 38-year-old woman with a de novo iTTP after exposure to the mRNA-based anti-coronavirus disease 2019 (COVID-19) vaccine produced by Pfizer-BioNTech. She presented with increased bruising and petechiae starting 2 weeks after receiving the first dose of the anti-COVID-19 vaccine. Laboratory data revealed a severe ADAMTS13-deficiency in combination with a very high autoantibody titer against ADAMTS13. She was successfully treated with plasma exchange, corticosteroids, rituximab, and caplacizumab. To our knowledge, this is the first case report of iTTP after mRNA-based COVID-19 vaccination in a previously TTP-naïve patient.

Unresponsive Thrombotic Thrombocytopenic Purpura (TTP): Challenges and Solutions

Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy secondary to a severely decreased A Disintegrin And Metalloprotease with ThromboSpondin type 1 repeats 13 (ADAMTS13) activity, resulting in the formation of widespread von Willebrand factor - and platelet-rich microthrombi. ADAMTS13 deficiency is mainly acquired through anti-ADAMTS13 autoantibodies in adults. With modern standards of care, unresponsive TTP has become rarer with a frequency of refractory/relapsing forms dropping from >40% to <10%. As patients with unresponsive TTP are at increased risk of mortality, prompt recognition and early therapeutic intensification are mandatory. Therapeutic options at the disposal of clinicians caring for patients with refractory TTP consist of increased ADAMTS13 supplementation, increased immunosuppression, and inhibition of von Willebrand factor adhesion to platelets. In this work, we focus on possible therapies for the management of patients with unresponsive TTP, and propose an algorithm for the management of these difficult cases.

ADAMTS13 and VWF activities guide individualized caplacizumab treatment in patients with aTTP

Introduction of the nanobody caplacizumab was shown to be effective in the treatment of acquired thrombotic thrombocytopenic purpura (aTTP) in the acute setting. The official recommendations include plasma exchange (PEX), immunosuppression, and the use of caplacizumab for a minimum of 30 days after stopping daily PEX. This study was a retrospective, observational analysis of the use of caplacizumab in 60 patients from 29 medical centers in Germany. Immunosuppressive treatment led to a rapid normalization of ADAMTS13 activities (calculated median, 21 days). In 35 of 60 patients, ADAMTS13 activities started to normalize before day 30 after PEX; in 11 of 60 patients, the treatment was extended beyond day 30; and in 5 patients, it was extended even beyond day 58 due to persistent autoimmune activity. In 34 of 60 instances, caplacizumab was stopped before day 30 with a favorable outcome whenever ADAMTS13 activities were >10%. In contrast, 11 of 34 patients with ADAMTS13 activities <10% at the time of stopping caplacizumab treatment developed a nonfavorable outcome (disease exacerbation or relapse). In some cases, prolongation of the treatment interval to every other day was feasible and resulted in a sustained reduction of von Willebrand factor activity. ADAMTS13 activity measurements are central for a rapid diagnosis in the acute setting but also to tailor disease management. An ADAMTS13 activity-guided approach seems safe for identifying the individual time point when to stop caplacizumab to prevent overtreatment and undertreatment; this approach will result in significant cost savings without jeopardizing the well-being of patients. In addition, von Willebrand factor activity may serve as a biomarker for drug monitoring.

Incidence, diagnosis, and outcome of immune-mediated thrombotic thrombocytopenic purpura: A nationwide survey by the Spanish registry of thrombotic thrombocytopenic purpura

BACKGROUND

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare disease characterized by the presence of anti-ADAMTS13 autoantibodies. Achieving accurate information on incidence and customary disease management is important to provide appropriate diagnostic and therapeutic resources. The aim of this study was to determine the incidence and outcomes of iTTP in Spain.

STUDY DESIGN AND METHODS

A cross-sectional survey was carried out among Spanish hospitals, focused on iTTP patients ≥16 years old attended between 2015 and 2017, and those at follow-up before that interval. Incidence, prevalence, mortality, refractoriness, exacerbations, treatment complications, relapses, and sequelae were estimated.

RESULTS

Forty-two hospitals covering roughly 20 million inhabitants answered the survey and reported 203 episodes (138 newly-diagnosed and 65 relapses), of which 193 (95.1%) were treated. Incidence was 2.67 (95% CI 1.90-3.45) patients per million inhabitants per year and prevalence 21.44 (95% CI% 19.10-23.73) patients per million inhabitants. At diagnosis, ADAMTS13 activity and anti-ADAMTS13 autoantibody were measured in 97% and 84.3% of reported episodes, respectively. Fifteen patients (7.4%) died as a direct consequence of iTTP, 6 of them before receiving any iTTP-specific treatment. Thirty-one (16.1%) of the 193 treated episodes were refractory to plasma exchange and corticosteroids, and 51 (26.4%) suffered at least one exacerbation.

CONCLUSION

iTTP incidence and prevalence were somewhat higher than those documented in neighboring countries. Together with data on treatments and outcomes, this information will allow us to better estimate what is needed to improve diagnosis and prognosis of iTTP patients in Spain.

Thrombotic Thrombocytopenic Purpura: Pathophysiology, Diagnosis, and Management

Thrombotic thrombocytopenic purpura (TTP) is a rare thrombotic microangiopathy characterized by microangiopathic hemolytic anemia, severe thrombocytopenia, and ischemic end organ injury due to microvascular platelet-rich thrombi. TTP results from a severe deficiency of the specific von Willebrand factor (VWF)-cleaving protease, ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 repeats, member 13). ADAMTS13 deficiency is most commonly acquired due to anti-ADAMTS13 autoantibodies. It can also be inherited in the congenital form as a result of biallelic mutations in the ADAMTS13 gene. In adults, the condition is most often immune-mediated (iTTP) whereas congenital TTP (cTTP) is often detected in childhood or during pregnancy. iTTP occurs more often in women and is potentially lethal without prompt recognition and treatment. Front-line therapy includes daily plasma exchange with fresh frozen plasma replacement and immunosuppression with corticosteroids. Immunosuppression targeting ADAMTS13 autoantibodies with the humanized anti-CD20 monoclonal antibody rituximab is frequently added to the initial therapy. If available, anti-VWF therapy with caplacizumab is also added to the front-line setting. While it is hypothesized that refractory TTP will be less common in the era of caplacizumab, in relapsed or refractory cases cyclosporine A, N-acetylcysteine, bortezomib, cyclophosphamide, vincristine, or splenectomy can be considered. Novel agents, such as recombinant ADAMTS13, are also currently under investigation and show promise for the treatment of TTP. Long-term follow-up after the acute episode is critical to monitor for relapse and to diagnose and manage chronic sequelae of this disease.

A multicenter laboratory assessment of a new automated chemiluminescent assay for ADAMTS13 activity

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) is a rare but potentially fatal disorder caused by ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) deficiency. Prompt identification/exclusion of TTP can thus be facilitated by rapid ADAMTS13 testing. The most commonly utilized (enzyme-linked immunosorbent assay [ELISA]-based) assay takes several hours to perform and so does not generally permit rapid testing.

OBJECTIVES

To evaluate the utility of a new automated test for ADAMTS13 activity, the HemosIL AcuStar ADAMTS13 Activity assay, based on chemiluminescence and able to be performed on an ACL AcuStar instrument within 33 minutes.

PATIENTS/METHODS

This multicenter (n = 8) assessment included testing of more than 700 test samples, with similar numbers of prospective (n = 348) and retrospective (n = 385) samples. The main comparator was the Technozym ADAMTS13 Activity ELISA. We also assessed comparative performance for detection of ADAMTS13 inhibitors using a Bethesda assay.

RESULTS

Overall, the chemiluminescent assay yielded similar results to the comparator ELISA, albeit with slight negative bias. ADAMTS13 inhibitor detection was also comparable, albeit with slight positive bias with the AcuStar assay. Assay precision was similar with both assays, and we also verified assay normal reference ranges.

CONCLUSIONS

The HemosIL AcuStar ADAMTS13 Activity assay provided results rapidly, which were largely comparable with the Technozym ADAMTS13 Activity ELISA assay, albeit lower on average. Conversely, inhibitor levels tended to be identified at a higher level on average. Thus, the HemosIL AcuStar ADAMTS13 Activity assay provides a fast and accurate means to quantitate plasma levels of ADAMTS13 for TTP/ADAMTS13 identification/exclusion, and potentially also for other applications.

An Atypical Presentation of Lemierre's Syndrome: Complicated by Thrombotic Thrombocytopenic Purpura

Lemierre’s syndrome is an oropharyngeal infection complicated by septic thrombophlebitis of the internal jugular vein, bacteremia, and septic emboli. It mainly occurs in immunocompetent individuals and was first reported in the early 1900s by physician Andre Lemierre. A 23-year-old male presented to our institution with sore throat, difficulty swallowing, left-sided ear pain, nausea, vomiting, subjective fevers, general malaise, right-sided rib pain, and anorexia. Complete blood cell count and metabolic panels revealed severe thrombocytopenia, mild anemia, acute kidney injury, and hyperbilirubinemia. Blood cultures grew Fusobacterium necrophorum. Ultrasound and computed tomography scan of the neck revealed thrombosis of the left internal jugular vein. ADAMTS13 activity was later reported to be markedly decreased at less than 2%, confirming a diagnosis of thrombotic thrombocytopenic purpura.

A critical evaluation of caplacizumab for the treatment of acquired thrombotic thrombocytopenic purpura

Introduction: Acquired thrombotic thrombocytopenic purpura (aTTP) is a thrombotic microangiopathy caused by inhibitory autoantibodies against ADAMTS13 protein. Until recently, the combination of plasma exchange (PEX) and immunosuppression has been the standard front-line treatment in this disorder. However, aTTP-related mortality, refractoriness, and relapse are still a matter of concern. Areas covered: The better understanding of the pathophysiological mechanisms of aTTP has allowed substantial improvements in the diagnosis and treatment of this disease. Recently, the novel anti-VWF nanobody caplacizumab has been approved for acute episodes of aTTP. Caplacizumab is capable to block the adhesion of platelets to VWF, therefore inhibiting microthrombi formation in the ADAMTS13-deficient circulation. In this review, the characteristics of caplacizumab together with the available data of its efficacy and safety in the clinical setting will be analyzed. Besides, the current scenario of aTTP treatment will be provided, including the role of other innovative drugs. Expert opinion: With no doubt, caplacizumab is going to change the way we treat aTTP. In combination with standard treatment, caplacizumab can help to significantly reduce aTTP-related mortality and morbidity and could spare potential long-term consequences by minimizing the risk of exacerbation.

Real-world data confirm the effectiveness of caplacizumab in acquired thrombotic thrombocytopenic purpura

Acquired thrombotic thrombocytopenic purpura (aTTP) is a rare but life-threatening condition. In 2018, the nanobody caplacizumab was approved for the treatment of adults experiencing an acute episode of aTTP, in conjunction with plasma exchange (PEX) and immunosuppression for a minimum of 30 days after stopping daily PEX. We performed a retrospective, observational analysis on the use of caplacizumab in 60 patients from 29 medical centers in Germany during acute disease management. Caplacizumab led to a rapid normalization of the platelet count (median, 3 days; mean 3.78 days). One patient died after late treatment initiation due to aTTP-associated complications. In 2 patients with initial disease presentation and in 4 additional patients with laboratory signs of an exacerbation or relapse after the initial therapy, PEX-free treatment regimens could be established with overall favorable outcome. Caplacizumab is efficacious in the treatment of aTTP independent of timing and ancillary treatment modalities. Based on this real-world experience and published literature, we propose to administer caplacizumab immediately to all patients with an acute episode of aTTP. Treatment decisions regarding the use of PEX should be based on the severity of the clinical presentation and known risk factors. PEX might be dispensable in some patients.