Reduced ADAMTS13 activity during TTP remission is associated with stroke in TTP survivors

Thrombotic thrombocytopenic purpura: 100 years of research on Moschcowitz syndrome

ABSTRACT

In the 100 years since Eli Moschcowitz reported the first case of thrombotic thrombocytopenic purpura (TTP), there has been remarkable awareness and progress in the diagnosis and management of this rare blood disorder. This progress initially was the result of careful clinical observations followed by well thought-out therapeutic interventions, with dual goals of both improving outcomes and discerning the pathophysiology of TTP. The discovery of the ADAMTS13 protease set in motion the efforts to more accurately define the specific etiologies of thrombotic microangiopathies (TMAs) based on objective, scientific data rather than clinical characterizations alone. This accurate differentiation led to better and more revealing clinical trials and advancements in the treatment of TTP and other TMAs. Further advances followed and included improvements in immune-suppressive therapy and targeted therapies of immune-mediated TTP (iTTP; caplacizumab) and congenital TTP (cTTP; recombinant ADAMTS13). The longitudinal study of patients with TTP revealed the unexpected risk for long-term complications in both patients with iTTP and those with cTTP in remission. Ongoing studies aim to further understand the prevalence, mechanisms, and appropriate screening for these mood disorders, neurocognitive deficits, and cardiovascular complications that develop at remarkably high rates and are associated with a decreased life expectancy. These discoveries are a result of the collaborative efforts of investigators worldwide that have been fostered by the frequent interactions of investigators via the International TTP Working Group meetings and TMA workshops held regularly at international meetings. These efforts will support the rapid pace of discovery and improved understanding of this rare disease.

Efficacy and safety of daratumumab in multiresistant immune-mediated thrombotic thrombocytopenic purpura

The immunosuppressive treatment of immune-mediated thrombotic thrombocytopenic purpura (iTTP) in patients with intolerance or refractoriness to the B-cell depleting monoclonal antibody rituximab remains debated. Daratumumab, a plasma cell-directed monoclonal antibody targeting CD38, represents a therapeutic option, but data are scarce. The French Thrombotic Microangiopathies Reference Center conducted a nationwide survey on iTTP patients treated with daratumumab. Nine episodes from seven patients were identified. Treatment was administered for A Disintegrin And Metalloproteinase with ThromboSpondin-1 motifs, 13th member (ADAMTS13) relapses while patients were otherwise in clinical response (N = 8), or during the acute phase of the disease following rituximab intolerance (N = 1). Patients have received a median of three previous therapeutic lines. ADAMTS13 activity improved in eight cases following daratumumab administration, including three cases where ADAMTS13 normalized. ADAMTS13 relapses occurred in three patients; in two cases, retreatment with daratumumab was successful. Median ADAMTS13 relapse-free survival was not reached; 12-month ADAMTS13 relapse-free survival was 56%. Daratumumab-related adverse events occurred in five cases and were non-severe infusion-related reactions in all cases. These results suggest that daratumumab may be an effective treatment option for iTTP patients with intolerance or refractoriness to rituximab.

The Highs and Lows of ADAMTS13 Activity

Severe deficiency of ADAMTS13 (<10 iu/dL) is diagnostic of thrombotic thrombocytopenic purpura (TTP) and leads to accumulation of ultra-large vWF multimers, platelet aggregation, and widespread microthrombi, which can be life-threatening. However, the clinical implications of a low ADAMTS13 activity level are not only important in an acute episode of TTP. In this article, we discuss the effects of low ADAMTS13 activity in congenital and immune-mediated TTP patients not only at presentation but once in a clinical remission. Evidence is emerging of the clinical effects of low ADAMTS13 activity in other disease areas outside of TTP, and here, we explore the wider impact of low ADAMTS13 activity on the vascular endothelium and the potential for recombinant ADAMTS13 therapy in other thrombotic disease states.

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.

ADAMTS13 in the New Era of TTP

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening, often immune-mediated disease that affects 2-13 persons per million per year. Hemolytic anemia, thrombocytopenia, and end-organ damage due to the formation of microthrombi are characteristic of TTP. ADAMTS13 is a disintegrin, metalloproteinase, cleaving protein of von Willebrand factor (VWF) that processes the VWF multimers to prevent them from interacting with platelets and, in turn, to microvascular thrombosis. Prompt diagnosis of TTP is critical yet challenging. Thrombotic microangiopathies have similar clinical presentation. Measurement of ADAMTS13 activity helps in the differential diagnosis. Less than 10% ADAMTS13 activity is indicative of TTP. Laboratory ADAMTS13 activity assays include incubating the test plasma with the substrate (full-length VWM multimers) and detection with direct or indirect measurement of the cleavage product. The purpose of this study is to examine the diagnostic potential, advantages, and weaknesses of the ADAMTS13 potency in TTP.

Immune Thrombotic Thrombocytopenic Purpura: Pathophysiology, Diagnosis, Therapy and Open Issues

Immune thrombotic thrombocytopenic purpura (iTTP) is a life-threatening thrombotic microangiopathy characterized by microangiopathic hemolytic anemia, thrombocytopenia, and ischemic end-organ injury due to microvascular platelet-rich thrombi. iTTP pathophysiology is based on a severe ADAMTS13 deficiency, the specific von Willebrand factor (vWF)-cleaving protease, due to anti-ADAMTS13 autoantibodies. Early diagnosis and treatment reduce the mortality. Frontline therapy includes daily plasma exchange (PEX) with fresh frozen plasma replacement and immunosuppression with corticosteroids. Caplacizumab has recently been added to frontline therapy. Caplacizumab is a nanobody that binds to the A1 domain of vWF, blocking the interaction of ultra-large vWF multimers with the platelet and thereby preventing the formation of platelet-rich thrombi. Caplacizumab reduces mortality due to ischemic events, refractoriness, and exacerbations after PEX discontinuation. Until now, the criteria for response to treatment mainly took into account the normalization of platelet count and discontinuation of PEX; with the use of caplacizumab leading to rapid normalization of platelet count, it has been necessary to redefine the response criteria, taking into account also the underlying autoimmune disease. Monitoring of ADAMTS13 activity is important to identify cases with a low value of activity (<10IU/L), requiring the optimization of immunosuppressive therapy with the addition of Rituximab. Rituximab is effective in patients with refractory disease or relapsing disease. Currently, the use of Rituximab has expanded, both in frontline treatment and during follow-up, as a pre-emptive approach. Some patients do not achieve ADAMTS13 remission following the acute phase despite steroids and rituximab treatment, requiring an individualized immunosuppressive approach to prevent clinical relapse. In iTTP, there is an increased risk of venous thrombotic events (VTEs) as well as arterial thrombotic events, and most occur after platelet normalization. Until now, there has been no consensus on the use of pharmacological thromboprophylaxis in patients on caplacizumab because the drug is known to increase bleeding risk.

Shades of Grey-The brain in TTP

In their paper, Hannan et al. suggest that new approaches to the management of the acute and remission phases of thrombotic thrombocytopenic purpura should be considered to address white matter changes seen in patients undergoing magnetic resonance imaging. Timely intervention may have significant implications for the long-term physical and mental health of patients. Commentary on: Hannan et al. Cognitive decline in thrombotic thrombocytopenic purpura survivors: The role of white matter health as assessed by MRI. Br J Haematol 2024;204:1005-1016.

Cognitive decline in thrombotic thrombocytopenic purpura survivors: The role of white matter health as assessed by MRI

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare condition caused by severe ADAMTS13 deficiency, leading to platelet aggregation and thrombosis. Despite treatment, patients are prone to cognitive impairment and depression. We investigated brain changes in iTTP patients during remission using advanced magnetic resonance imaging (MRI) techniques, correlating these changes with mood and neurocognitive tests. Twenty iTTP patients in remission (30 days post-haematological remission) were compared with six healthy controls. MRI scans, including standard and specialized sequences, were conducted to assess white matter health. Increased T1 relaxation times were found in the cingulate cortex (p < 0.05), and elevated T2 relaxation times were observed in the cingulate cortex, frontal, parietal and temporal lobes (p < 0.05). Pathological changes in these areas are correlated with impaired cognitive and depressive scores in concentration, short-term memory and verbal memory. This study highlights persistent white matter damage in iTTP patients, potentially contributing to depression and cognitive impairment. Key regions affected include the frontal lobe and cingulate cortex. These findings have significant implications for the acute and long-term management of iTTP, suggesting a need for re-evaluation of treatment approaches during both active phases and remission. Further research is warranted to enhance our understanding of these complexities.

Bortezomib in relapsed/refractory immune thrombotic thrombocytopenic purpura: A single-centre retrospective cohort and systematic literature review

Immune thrombotic thrombocytopenic purpura (iTTP) is a rare and life-threatening haematological condition. Initial treatment involves plasma exchange (PLEX), corticosteroids, caplacizumab and rituximab. In relapsed and refractory cases despite initial treatments, further immune-modulating therapy includes the proteasome inhibitor, bortezomib. Evidence for bortezomib in this setting is limited to case reports and case series. We report our experience and perform a systematic review of the literature. We identified 21 publications with 28 unique patients in addition to our cohort of eight patients treated with bortezomib. The median age of patients was 44 years (IQR: 27-53) and 69% female. They were usually in an initial, refractory presentation of iTTP where they had received PLEX, corticosteroids, rituximab and another line of therapy. After bortezomib administration, 72% of patients had a complete response, with 85% maintaining a durable response without relapse at the last follow-up.

Should we consider caplacizumab as routine treatment for acute thrombotic thrombocytopenic purpura? An expert perspective on the pros and cons

INTRODUCTION

Immune thrombotic thrombocytopenic purpura (iTTP) is a rare and life-threatening disorder. Caplacizumab has been the latest drug incorporated into the initial treatment of acute episodes, allowing for faster platelet recovery and a decrease in refractoriness, exacerbation, thromboembolic events, and mortality. However, caplacizumab is also associated with a bleeding risk and higher treatment costs, which prevent many centers from using it universally.

AREAS COVERED

Studies that included iTTP and/or caplacizumab to date were selected for this review using PubMed and MEDLINE platforms. We describe outcomes in the pre-caplacizumab era and after it, highlighting the benefits and risks of its use early in frontline, and also pointing out special situations that require careful management.

EXPERT OPINION

It is clear that the availability of caplacizumab has significantly and favorably impacted the management of iTTP patients. Whether this improvement is cost-effective still remains uncertain, and data on long-term sequelae and different healthcare systems will help to clarify this point. In addition, evidence of the bleeding/thrombotic risk of iTTP patients under this drug needs to be better addressed in future studies.

Longitudinal characterization of symptoms, healthcare resource utilization, and costs among people with thrombotic thrombocytopenic purpura compared with non-thrombotic thrombocytopenic purpura controls

AIMS

Thrombotic thrombocytopenic purpura (TTP) is an ultra-rare blood disorder, characterized by severe ADAMTS13 deficiency. Affected individuals present with potentially life-threatening acute events and may experience sub-acute and chronic TTP manifestations often resulting in long-term organ damage. Incremental symptom prevalence before, during, and after an acute event as well as healthcare resource utilization (HCRU) and costs during and after an acute event were compared between people with TTP and matched non-TTP controls.

METHODS

This retrospective, matched study used data from Merative MarketScan Commercial Database and Medicare Supplemental Database (from January 1, 2008, through September 30, 2021) to identify people with TTP (inpatient diagnosis for "thrombotic microangiopathy (TMA)" or "congenital TTP," and ≥1 claim for plasma exchange or infusion). People with TTP were matched (1:2) with non-TTP controls on age, sex, geographic region, index year, and select Elixhauser comorbidities.

RESULTS

255 people with TTP were matched with 510 non-TTP controls. Both cohorts had a mean age of 43.9 years; 71% were female. Overall, more people with TTP reported symptoms compared with non-TTP controls prior to (51% vs 43%), during (99% vs 52%), and after an acute event (85% vs 50%; p < 0.05 for all periods). Symptom prevalence decreased following an acute event compared with during an acute event, but remained high-85% of people with TTP experienced symptoms compared with 50% of non-TTP controls. HCRU and mean costs per patient per month were significantly higher in all care settings among people with TTP compared with non-TTP controls (p < 0.05).

LIMITATIONS

Identification of patient populations may have been limited due to coding errors, as the data were obtained from an administrative claims database.

CONCLUSIONS

TTP is associated with a substantial symptom burden and increased costs and HCRU during and up to almost a year after acute events, demonstrating the longitudinal burden of this disease.

A British Society for Haematology Guideline: Diagnosis and management of thrombotic thrombocytopenic purpura and thrombotic microangiopathies

The objective of this guideline is to provide healthcare professionals with clear, up-to-date and practical guidance on the management of thrombotic thrombocytopenic purpura (TTP) and related thrombotic microangiopathies (TMAs), including complement-mediated haemolytic uraemic syndrome (CM HUS); these are defined by thrombocytopenia, microangiopathic haemolytic anaemia (MAHA) and small vessel thrombosis. Within England, all TTP cases should be managed within designated regional centres as per NHSE commissioning for highly specialised services.

Predictors of acute ischemic cerebral lesions in immune-mediated thrombotic thrombocytopenic purpura and hemolytic uremic syndrome

BACKGROUND

The immune form of thrombotic thrombocytopenic purpura (iTTP) and the hemolytic and uremic syndrome (HUS) are two major forms of thrombotic microangiopathy (TMA). Their treatment has been recently greatly improved. In this new era, both the prevalence and predictors of cerebral lesions occurring during the acute phase of these severe conditions remain poorly known.

AIM

The prevalence and predictors of cerebral lesions appearing during the acute phase of iTTP and Shiga toxin-producing Escherichia coli-HUS or atypical HUS were evaluated in a prospective multicenter study.

METHODS

Univariate analysis was performed to report the main differences between patients with iTTP and those with HUS or between patients with acute cerebral lesions and the others. Multivariable logistic regression analysis was used to identify the potential predictors of these lesions.

RESULTS

Among 73 TMA cases (mean age 46.9 ± 16 years (range 21-87 years) with iTTP (n = 57) or HUS (n = 16), one-third presented with acute ischemic cerebral lesions on magnetic resonance imagery (MRI); two individuals also had hemorrhagic lesions. One in ten patients had acute ischemic lesions without any neurological symptom. The neurological manifestations did not differ between iTTP and HUS. In multivariable analysis, three factors predicted the occurrence of acute ischemic lesions on cerebral MRI: (1) the presence of old infarcts on cerebral MRI, (2) the level of blood pulse pressure, (3) the diagnosis of iTTP.

CONCLUSION

At the acute phase of iTTP or HUS, both symptomatic and covert ischemic lesions are detected in one third of cases on MRI. Diagnosis of iTTP and the presence of old infarcts on MRI are associated with the occurrence of such acute lesions as well as increased blood pulse pressure, that may represent a potential target to further improve the therapeutic management of these conditions.

Five years of caplacizumab - lessons learned and remaining controversies in immune-mediated thrombotic thrombocytopenic purpura

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare hematologic disease caused by autoantibodies against ADAMTS-13 that trigger microangiopathic hemolytic anemia. Therapeutic plasma exchange and glucocorticoids have been the mainstay of treatment for the past 30 years. In 2019, caplacizumab was approved as an addition to this regimen for the acute treatment of iTTP. Randomized controlled trials and real-world evidence have shown that caplacizumab reduces the time to platelet count normalization, refractoriness, and exacerbations of the disease, with an acceptable safety profile. In the past 5 years, there have been arguments against the upfront use of caplacizumab in all patients with iTTP, particularly related to the perceived lack of clinical benefit, safety concerns related to bleeding risk, and high costs. This perspective aimed to address these concerns in the context of the experience of expert centers that have used the drug for >5 years.

Cardiovascular Disease and Stroke in Immune TTP-Challenges and Opportunities

Advances in the management of immune thrombotic thrombocytopenic purpura (iTTP) have dramatically improved outcomes of acute TTP episodes, and TTP is now treated as a chronic, relapsing disorder. It is now recognized that iTTP survivors are at high risk for vascular disease, with stroke and myocardial infarction occurring at younger ages than in the general population, and cardiovascular disease is the leading cause of premature death in this population. iTTP appears to have a phenotype of accelerated vascular aging with a particular predilection for cerebral circulation, and stroke is much more common than myocardial infarction. In addition to traditional cardiovascular risk factors, low ADAMTS13 activity during clinical remission may be a risk factor for some of these outcomes, such as stroke. Recent studies also suggest that Black patients, who are disproportionately affected by iTTP in the United States, are at higher risk of adverse cardiovascular outcomes, likely due to multifactorial reasons. Additional research is required to establish the risk factors and mechanisms underlying these complications in order to institute optimal screening strategies and identify interventions to improve outcomes.

Silent cerebral infarction during immune TTP remission: prevalence, predictors, and impact on cognition

Immune thrombotic thrombocytopenic purpura (iTTP) survivors have increased risk of cardiovascular disease, including strokes, and report persistent cognitive difficulties during remission. We conducted this prospective study involving iTTP survivors during clinical remission to determine the prevalence of silent cerebral infarction (SCI), defined as magnetic resonance imaging (MRI) evidence of brain infarction without corresponding overt neurodeficits. We also tested the hypothesis that SCI is associated with cognitive impairment, assessed using the National Institutes of Health ToolBox Cognition Battery. For cognitive assessments, we used fully corrected T scores adjusted for age, sex, race, and education. Based on the diagnostic and statistical manual 5 criteria, we defined mild and major cognitive impairment as T scores with a 1 or 2 standard deviation (SD) and >2 SD below the mean on at least 1 test, respectively. Forty-two patients were enrolled, with 36 completing MRIs. SCI was present in 50% of the patients (18), of which 8 (44.4%) had prior overt stroke including during acute iTTP. Patients with SCI had higher rates of cognitive impairment (66.7% vs 27.7%; P = .026), including major cognitive impairment (50% vs 5.6%; P = .010). In separate logistic regression models, SCI was associated with any (mild or major) cognitive impairment (odds ratio [OR] 10.5 [95% confidence interval (95% CI), 1.45-76.63]; P = .020) and major cognitive impairment (OR 7.98 [95% CI, 1.11-57.27]; P = .039) after adjusting for history of stroke and Beck depression inventory scores. MRI evidence of brain infarction is common in iTTP survivors; the strong association of SCI with impaired cognition suggests that these silent infarcts are neither silent nor innocuous.

The Specificities of Thrombotic Thrombocytopenic Purpura at Extreme Ages: A Narrative Review

Thrombotic thrombocytopenic purpura (TTP) is a rare and life-threatening thrombotic microangiopathy (TMA) related to a severe ADAMTS13 deficiency, the specific von Willebrand factor (VWF)-cleaving protease. This deficiency is often immune-mediated (iTTP) and related to the presence of anti-ADAMTS13 autoantibodies that enhance its clearance or inhibit its VWF processing activity. iTTP management may be challenging at extreme ages of life. International cohorts of people with TTP report delayed diagnoses and misdiagnoses in children and elderly people. Child-onset iTTP shares many features with adult-onset iTTP: a female predominance, an idiopathic presentation, and the presence of neurological disorders and therapeutic strategies. Long-term follow-ups and a transition from childhood to adulthood are crucial to preventing iTTP relapses, in order to identify the occurrence of other autoimmune disorders and psychosocial sequelae. In contrast, older iTTP patients have an atypical clinical presentation, with delirium, an atypical neurological presentation, and severe renal and cardiac damages. They also have a poorer response to treatment and prognosis. Long-term sequelae are highly prevalent in older patients. Prediction scores for iTTP diagnoses are not used for children and have a lower sensitivity and specificity in patients over 60 years old. ADAMTS13 remains the unique biological marker that is able to definitely confirm or rule out the diagnosis of iTTP and predict relapses during follow-ups.

Machine learning algorithms assisted identification of post-stroke depression associated biological features

Objectives

Post-stroke depression (PSD) is a common and serious psychiatric complication which hinders functional recovery and social participation of stroke patients. Stroke is characterized by dynamic changes in metabolism and hemodynamics, however, there is still a lack of metabolism-associated effective and reliable diagnostic markers and therapeutic targets for PSD. Our study was dedicated to the discovery of metabolism related diagnostic and therapeutic biomarkers for PSD.

Methods

Expression profiles of GSE140275, GSE122709, and GSE180470 were obtained from GEO database. Differentially expressed genes (DEGs) were detected in GSE140275 and GSE122709. Functional enrichment analysis was performed for DEGs in GSE140275. Weighted gene co-expression network analysis (WGCNA) was constructed in GSE122709 to identify key module genes. Moreover, correlation analysis was performed to obtain metabolism related genes. Interaction analysis of key module genes, metabolism related genes, and DEGs in GSE122709 was performed to obtain candidate hub genes. Two machine learning algorithms, least absolute shrinkage and selection operator (LASSO) and random forest, were used to identify signature genes. Expression of signature genes was validated in GSE140275, GSE122709, and GSE180470. Gene set enrichment analysis (GSEA) was applied on signature genes. Based on signature genes, a nomogram model was constructed in our PSD cohort (27 PSD patients vs. 54 controls). ROC curves were performed for the estimation of its diagnostic value. Finally, correlation analysis between expression of signature genes and several clinical traits was performed.

Results

Functional enrichment analysis indicated that DEGs in GSE140275 enriched in metabolism pathway. A total of 8,188 metabolism associated genes were identified by correlation analysis. WGCNA analysis was constructed to obtain 3,471 key module genes. A total of 557 candidate hub genes were identified by interaction analysis. Furthermore, two signature genes (SDHD and FERMT3) were selected using LASSO and random forest analysis. GSEA analysis found that two signature genes had major roles in depression. Subsequently, PSD cohort was collected for constructing a PSD diagnosis. Nomogram model showed good reliability and validity. AUC values of receiver operating characteristic (ROC) curve of SDHD and FERMT3 were 0.896 and 0.964. ROC curves showed that two signature genes played a significant role in diagnosis of PSD. Correlation analysis found that SDHD (r = 0.653, P &lt; 0.001) and FERM3 (r = 0.728, P &lt; 0.001) were positively related to the Hamilton Depression Rating Scale 17-item (HAMD) score.

Conclusion

A total of 557 metabolism associated candidate hub genes were obtained by interaction with DEGs in GSE122709, key modules genes, and metabolism related genes. Based on machine learning algorithms, two signature genes (SDHD and FERMT3) were identified, they were proved to be valuable therapeutic and diagnostic biomarkers for PSD. Early diagnosis and prevention of PSD were made possible by our findings.

Therapeutic plasma exchange-free treatment for first-episode TTP: A systematic review

OBJECTIVE

Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy (TMA), and therapeutic plasma exchange (TPE) is currently the standard treatment. However, TPE sometimes cannot be implemented. The aim of this study was to systematically review patients with a first TTP episode who were treated without TPE.

METHOD

The PubMed, Embase, Web of Science and Cochrane Library databases were searched by two investigators independently to collect case reports and clinical studies on TTP patients treated without TPE. After removing duplicate records and records that did not meet the inclusion criteria, the patients' data of eligible studies, including the basic characteristics, treatment regimens, and outcomes were extracted for further analysis.

RESULTS

A total of 5338 potentially relevant original studies were identified, from which 21 studies, including 14 cases, 3 case series and 4 retrospective studies, met eligibility requirements and were included. Treatment regimens in the absence of TPE were found to vary based on individual information. Most patients recovered, with normal platelet counts and ADAMT13 activity at discharge. In the meta-analysis of retrospective studies, the TPE-free group had no higher mortality than the TPE-treated group.

CONCLUSION

Our study shows that TPE-free treatment may not increase the mortality of TTP patients, which provides a new treatment concept for patients with first episodes of TTP. However, the current evidence is not high due to the lack of randomized controlled trials, so more well-designed prospective clinical trials are warranted to investigate the safety and efficacy of TPE-free treatment regimens in TTP patients.

Immune thrombotic thrombocytopenic purpura: Spotlight on long-term outcomes and survivorship

Advances in diagnosis and treatment have dramatically improved survival of acute immune thrombotic thrombocytopenic purpura (iTTP) and iTTP has evolved from an acute fatal condition to a chronic relapsing disorder. In addition to the risk of iTTP relapse, iTTP survivors are at risk of multiple adverse health outcomes including higher than expected rates of all-cause mortality, increased rates of stroke and other cardiovascular disease, and higher rates of morbidities such as obesity, hypertension, and autoimmune disorders. iTTP survivors also report neurocognitive impairment, depression, and reduced quality of life. Women with iTTP are at risk for recurrent iTTP, preeclampsia, and other maternal and fetal complications in subsequent pregnancies. ADAMTS13 activity during clinical remission has emerged as an important targetable risk factor for iTTP relapse and other outcomes including stroke and all-cause mortality. This review summarizes current literature regarding the epidemiology and potential mechanisms for adverse long-term sequelae of iTTP, outlines current best practices in iTTP survivorship care, and highlights a research agenda to improve long-term iTTP outcomes.

Two ischemic stroke events within 48 h: a case report of an unusual presentation of thrombotic thrombocytopenic purpura

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) considers a rare cause of ischemic stroke (IS). We reported a case of a newly diagnosed patient with acquired immune-mediated TTP (iTTP), in whom two IS events developed during 48 h.

CASE PRESENTATION

A 59-year-old diabetic male was presented to the hospital 24 h after symptoms onset, including left hemiparesis, dysarthria, and decreased consciousness. A brain CT scan was performed with the suspicion of acute IS, indicating infarct lesions in the right middle cerebral artery (MCA) territory. The patient was not eligible for thrombolytic therapy due to admission delay. Over the next 24 h, the patient's neurological condition deteriorated, and the second brain CT scan showed new ischemic lesions in the left MCA territory. Initial laboratory evaluation indicated thrombocytopenia without evidence of anemia. However, in the following days, thrombocytopenia progressed, and microangiopathic hemolytic anemia (MAHA) developed. The ADAMTS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) activity and inhibitors assay confirmed the diagnosis of iTTP. The patient underwent plasma exchange activity and inhibitors assay confirmed the diagnosis of iTTP. The patient underwent and pulse IV methylprednisolone. Rituximab was also added due to the refractory course of the disease. After a prolonged hospital course, he had considerable neurologic recovery and was discharged.

CONCLUSIONS

Clinicians should consider two points. First, TTP should be considered in any patient presenting with IS and having thrombocytopenia or anemia without other symptoms of TTP. Second, worsening the patient's condition during hospitalization may indicate a new stroke and should be investigated immediately.

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.

Long-term follow-up of patients treated with caplacizumab and safety and efficacy of repeat caplacizumab use: Post-HERCULES study

INTRODUCTION

Caplacizumab demonstrated efficacy and safety in patients with immune-mediated thrombotic thrombocytopenic purpura (iTTP) in the phase 3 HERCULES trial. However, data on long-term outcomes following caplacizumab treatment are limited.

OBJECTIVES

The post-HERCULES trial (NCT02878603) evaluated long-term outcomes of patients with iTTP treated with caplacizumab in HERCULES and safety and efficacy of repeated caplacizumab use.

PATIENTS/METHODS

Over 3 years of follow-up, patients could receive open-label caplacizumab with therapeutic plasma exchange (TPE) and immunosuppressive therapy (IST) in case of recurrence. Adverse events (AEs) were assessed during the overall study period (intention-to-observe [ITO] population) and during recurrences (recurrence population). TTP-related events (TTP-related death, recurrence, major thromboembolic events) were assessed in the efficacy ITO population (patients without recurrence during HERCULES or before post-HERCULES).

RESULTS

Among 104 enrolled patients, incidences of AEs and serious AEs were similar between patients who had received caplacizumab + TPE + IST during HERCULES (n = 75) and those treated with placebo + TPE + IST (placebo; n = 29). TTP-related events occurred in 8% of patients (4/49) randomized to caplacizumab during HERCULES versus 38% (11/29) randomized to placebo. Nineteen patients had ≥1 recurrence; 13 of these were treated with caplacizumab. The first recurrence episode was resolved or resolving for all patients treated with caplacizumab, including nine patients with repeat caplacizumab use. All second recurrences (6/6) were resolved. Safety profile of caplacizumab for treatment of recurrence was consistent with HERCULES; most bleeding events were nonserious. No major cases of organ dysfunction were observed.

CONCLUSIONS

Long-term follow-up supports the safety and efficacy of caplacizumab for iTTP and its repeated use for recurrences.

Thrombotic Thrombocytopenic Purpura: From 1972 to 2022 and Beyond

This review tells the story of my personal experience with thrombotic thrombocytopenic purpura (TTP). It begins with my first encounter with TTP 50 years ago when 2 sisters presented 2 years apart, both pregnant and both died. At that time, I knew nothing about hereditary TTP (hTTP), the risks of pregnancy, or effective treatments. In 1991, a year after I moved to Oklahoma, therapeutic plasma exchange (TPE) was established as an effective treatment. With the availability of effective treatment, the number of patients presenting with suspected TTP soared. The diagnosis of TTP was imprecise. I worked with the Oklahoma Blood Institute (OBI) to understand the management of TTP. Because the OBI provided all TPE procedures for most of Oklahoma, we saw all consecutive patients within a defined geographic area who were identified at a uniform time early in the course of their TTP, without selection or referral bias. It was an inception cohort; this became the Oklahoma TTP Registry. In 2001, we began a very successful collaboration with the University of Bern, Switzerland, to measure ADAMTS13 activity in all of our patients. From our patients, we learned that acquired, autoimmune TTP (iTTP) is a chronic disease with risks for cognitive impairment and depression. Recognition in 2012 of three sisters with hTTP was reminiscent of the beginning of my story. hTTP has risks for multiple severe morbidities, beginning at birth and especially during pregnancy. Future management of both iTTP and hTTP will be more effective and more convenient.

Prevalence of neuropsychiatric symptoms and stroke in patients with hereditary thrombotic thrombocytopenic purpura

In this article, Borogovac et al emphasized the burden of stroke and neuropsychiatric symptoms in patients with hereditary thrombotic thrombocytopenic purpura (hTTP) based on an analysis of the International hTTP Registry. Given the rarity of hTTP, patient numbers were small; nevertheless, the prevalence of stroke reached 100% in patients over the age of 50. Nearly all patients also had evidence of neuropsychiatric symptoms. These data confirm the need to diagnose hTTP as early as possible and support the use of prophylaxis to prevent future events.

How I treat immune-mediated thrombotic thrombocytopenic purpura after hospital discharge

Immune-mediated thrombocytopenic purpura (iTTP) is a thrombotic microangiopathy characterized by an acquired ADAMTS13 deficiency as a result of the presence of an antibody inhibitor of ADAMTS13 leading to the formation of ultralarge von Willebrand multimers. Treatment of iTTP includes plasma exchange, high-dose glucocorticoids, rituximab, and, more recently, caplacizumab, to prevent the development of exacerbations. There is the risk of both relapse and long-term complications that include neurocognitive deficits and cardiovascular events that occur in patients in remission after recovery from an acute iTTP episode. Data on the risk factors for the development of these complications, the appropriate screening, and treatment are limited due to the paucity of research. This article is a review of the current understanding on the risk factors for exacerbation, relapse, and long-term complications of iTTP and discusses an approach to observing patients with iTTP after hospital discharge and during the long-term follow-up in the outpatient setting.

Recent advances in the management of immune-mediated thrombotic thrombocytopenic purpura

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a potentially life-threatening thrombotic microangiopathy caused by autoantibody-mediated severe ADAMTS13 deficiency. TTP should be suspected in patients with microangiopathic hemolytic anemia and thrombocytopenia without a definite cause. Early detection of iTTP and prompt treatment with plasma exchange and corticosteroids are essential. Rituximab administration should be considered for refractory or relapsed iTTP, and can be used as a first-line adjuvant or preemptive therapy. Treatment with caplacizumab, a novel anti-von Willebrand factor nanobody, resulted in a faster time to platelet count response, significant reduction in iTTP-related deaths, and reduced incidence of refractory iTTP. TTP survivors showed a higher rate of chronic morbidities, including cardiovascular disease and neurocognitive impairment, which can lead to a poor quality of life and higher mortality rate. Meticulous long-term follow-up of TTP survivors is crucial.

Deletion of platelet CLEC-2 decreases GPIbα-mediated integrin αIIbβ3 activation and decreases thrombosis in TTP

Microvascular thrombosis in patients with thrombotic thrombocytopenic purpura (TTP) is initiated by GPIbα-mediated platelet binding to von Willebrand factor (VWF). Binding of VWF to GPIbα causes activation of the platelet surface integrin αIIbβ3. However, the mechanism of GPIbα-initiated activation of αIIbβ3 and its clinical importance for microvascular thrombosis remain elusive. Deletion of platelet C-type lectin-like receptor 2 (CLEC-2) did not prevent VWF binding to platelets but specifically inhibited platelet aggregation induced by VWF binding in mice. Deletion of platelet CLEC-2 also inhibited αIIbβ3 activation induced by the binding of VWF to GPIbα. Using a mouse model of TTP, which was created by infusion of anti-mouse ADAMTS13 monoclonal antibodies followed by infusion of VWF, we found that deletion of platelet CLEC-2 decreased pulmonary arterial thrombosis and the severity of thrombocytopenia. Importantly, prophylactic oral administration of aspirin, an inhibitor of platelet activation, and therapeutic treatment of the TTP mice with eptifibatide, an integrin αIIbβ3 antagonist, reduced pulmonary arterial thrombosis in the TTP mouse model. Our observations demonstrate that GPIbα-mediated activation of integrin αIIbβ3 plays an important role in the formation of thrombosis in TTP. These observations suggest that prevention of platelet activation with aspirin may reduce the risk for thrombosis in patients with TTP.

TTP: From empiricism for an enigmatic disease to targeted molecular therapies

The 100th anniversary of the first description of Thrombotic Thrombocytopenic Purpura (TTP) as a disease by Dr. Eli Moschcowitz approaches. For many decades, TTP remained mostly a mysterious fatal condition, where diagnosis was often post-mortem. Initially a pentad of symptoms was identified, a pattern that later revealed to be fallible. Sporadic observations led to empiric interventions that allowed for the first impactful breakthrough in TTP treatment, almost 70 years after its first description: the introduction of plasma exchange and infusions as treatments. The main body of knowledge within the field was gathered in the latest three decades: patient registries were set and proved crucial for advancements; the general mechanisms of disease have been described; the diagnosis was refined; new treatments and biomarkers with improvements on prognosis and management were introduced. Further changes and improvements are expected in the upcoming decades. In this review, we provide a brief historic overview of TTP, as an illustrative example of the success of translational medicine enabling to rapidly shift from a management largely based on empiricism to targeted therapies and personalized medicine, for the benefit of patients. Current management options and present and future perspectives in this still evolving field are summarized.

Cerebral Infarction due to Severe ADAMTS-13 Deficiency with Normal Hematological Parameters: A Potentially Cause of Cryptogenic Stroke

OBJECTIVES

Thrombotic thrombocytopenic purpura (TTP) is a microangiopathy resulting from an inherited or acquired severe deficiency in a disintegrin and metalloproteinase called ADAMTS-13. Acquired or immune TTP is classically described as a pentad of microangiopathic hemolytic anemia (MAHA), thrombocytopenia, fever, renal insufficiency and neurological symptoms. Thrombotic thrombocytopenic purpura has been linked to stroke with the presence of hematologic abnormalities but whether or not severe ADAMTS-13 deficiency can cause stroke without hematological abnormalities is unknown.

MATERIALS AND METHODS

As part of routine clinical care, we identified four cases of recurrent stroke attributed to severe deficiency of ADAMTS-13. We also conducted a search of a centralized electronic health record database including all inpatients and outpatient charts at a single academic medical center over the last ten years in an attempt to identify additional cases.

RESULTS

Here we present four cases of stroke and severe ADAMTS-13 deficiency where stroke episodes occurred without microangiopathic hemolytic anemia or severe thrombocytopenia. These cases show the need to consider severe ADAMTS-13 deficiency in the setting of recurrent cryptogenic stroke in young patients.

CONCLUSIONS AND RELEVANCE

TTP directed therapies may be considered for patients with recurrent stroke who have extremely low ADAMTS-13 levels, even when platelet and hemoglobin values are normal.

Cardiovascular disease is a leading cause of mortality among TTP survivors in clinical remission

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) survivors experience high rates of adverse health sequelae and increased mortality over long-term follow-up. We conducted this multicenter cohort study to evaluate long-term mortality and causes of death in iTTP survivors. Between 2003 and 2020, 222 patients were enrolled in the Ohio State University and Johns Hopkins TTP registries and followed for a median of 4.5 (interquartile range [IQR], 75 0.4-11.5) years. Nine patients died during their first iTTP episode, and 29 patients died during follow-up. Mortality rate was 1.8 times higher than expected from an age-, sex-, and race-adjusted reference population. Cardiovascular disease was a leading primary cause of death (27.6%) tied with relapsed iTTP (27.6%), followed by malignancy (20.7%), infection (13.8%), and other causes (10.3%). Male sex (hazard ratio [HR], 3.74; 95% confidence interval [CI], 1.65-8.48), increasing age (HR, 1.04; 95% CI, 1.01-1.07), and number of iTTP episodes (HR, 1.10; 95% CI, 1.01-1.20) were associated with mortality in a model adjusted for African American race (HR, 0.70; 95% CI, 0.30-1.65), hypertension (HR, 0.47; 95% CI, 0.20-1.08), chronic kidney disease (HR 1.46; 95% CI, 0.65-3.30), and site (HR, 1.46; 95% CI, 0.64-3.30). There was a trend toward shorter survival in patients with lower ADAMTS13 activity during remission (P = .078). Our study highlights the need for survivorship care and investigation focused on cardiovascular disease and early mortality in TTP survivors.

Delayed diagnosis of congenital thrombotic thrombocytopenic purpura in a patient with recurrent strokes

Congenital thrombotic thrombocytopenic purpura (cTTP) is caused by ADAMTS13 mutations and associated with high risk of microvascular thrombosis. A 58 year old female had an ischemic stroke during hormonal fertility, and a TIA a year after. She suffered another stroke 18 years later while on warfarin. Four months after she developed severe thrombocytopenia, mild anemia, and increased LDH. Blood film showed schistocytes. She was hospitalized with presumptive TTP. ADAMTS 13 activity was undetectable without inhibitor. She developed another stroke and received plasma exchange. A homozygote ADAMTS 13 mutation was identified. Despite plasma, the ADAMTS13 activity remained < 10% and she had another stroke. Recombinant ADAMTS13 therapy was obtained through compassionate use. She receives weekly infusions maintaining ADAMTS13 trough levels above 10% without thrombotic recurrences. This case underscores the need to recognize cTTP as a cause of cryptogenic strokes, and the diagnostic value of the peripheral blood film. rADAMTS13 replacement may prevent recurrences.

Management of acquired, immune thrombocytopenic purpura (iTTP): beyond the acute phase

Modern therapy for acute TTP has resulted in a dramatic improvement in outcomes, with the combination of plasma exchange, immunosuppression, and caplacizumab being associated with >90% survival rates following an acute episode. TTP is no longer associated with just the acute episode, but requires long-term follow-up. There remains significant morbidity associated with acute TTP, and many patients suffer marked neuropsychological sequelae, including impairment in cognitive functioning, affective disorders, and reduction in health-related quality of life measures. The focus of management beyond the acute phase centres on relapse prevention, via careful monitoring of patients and the use of either ad hoc or regular immunosuppressive therapies. The main therapy used is rituximab, but despite more limited evidence, other immunosuppressive therapies may be required to aim for normalisation of ADAMTS 13 activity. Follow-up with a reduction in ADAMTS 13 activity levels (ADAMTS 13 relapse), rituximab is central to normalisation of activity levels and prevention of a clinical relapse. Fundamental to elective therapy is the role of ADAMTS 13 activity monitoring, and impact of reduced ADAMTS13 activity on end organ damage. This review discusses monitoring and treatment strategy for long-term management of TTP, including the variety of therapies available to maintain remission, prevent relapse and a summary of a long-term treatment pathway.

Severe thrombocytopenia and microangiopathic hemolytic anemia in pregnancy: A guide for the consulting hematologist

A hematologist receives a call from a maternal-fetal medicine (MFM) physician about a previously healthy patient who became ill at 25 weeks' gestation. Her mental status is deteriorating. There are signs of fetal distress. Platelet count and hemoglobin are falling. The MFM physician is considering the hemolysis, elevated liver enzymes and low platelet count (HELLP) syndrome. For the hematologist, everything seems unfamiliar. Our goal is to provide hematologists with the fundamental knowledge required for understanding and managing these patients who become suddenly and seriously ill during pregnancy and in whom thrombocytopenia and microangiopathic hemolytic anemia are part of their presentation.

Major adverse cardiovascular events in survivors of immune-mediated thrombotic thrombocytopenic purpura

Cardiovascular disease is a leading cause of death in survivors of immune-mediated thrombotic thrombocytopenic purpura (iTTP), but the epidemiology of major adverse cardiovascular events (MACE) in iTTP survivors is unknown. We evaluated the prevalence and risk factors for MACE, defined as the composite of non-fatal or fatal myocardial infarction (MI), stroke, and cardiac revascularization, during clinical remission in two large iTTP cohorts (Johns Hopkins University and Ohio State University). Of 181 patients followed for ≥ 3 months after recovery from acute iTTP, 28.6% had a MACE event over a median follow up of 7.6 years. Stroke was the most common type of MACE (18.2%), followed by non-fatal MI (6.6%), cardiac revascularization (4.9%) and fatal MI (0.6%). Compared to the general United States population, iTTP survivors were younger at first stroke in remission (males [56.5 years vs. 68.6 years, p = 0.031], females [49.7 years vs. 72.9 years, p <  0.001]) or MI in remission (males [56.5 years vs. 65.6 years, p <  0.001] and females [53.1 years vs. 72.0 years, p < 0.001]). Age (HR 1.03 [95% CI 1.002-1.054]), race (Black/Other vs. White) (HR 2.32 [95% CI 1.12-4.82]), and diabetes mellitus (HR 2.37 [95% CI 1.09-0.03]) were associated with MACE in a Cox regression model also adjusted for sex, hypertension, obesity, hyperlipidemia, chronic kidney disease, atrial fibrillation, autoimmune disease, and relapsing iTTP. Remission ADAMTS13 activity was not significantly associated with MACE. In conclusion, iTTP survivors experience high rates of MACE and may benefit from aggressively screening for and managing cardiovascular risk factors.

Predictors of relapse and preventative strategies in immune thrombotic thrombocytopenic purpura

INTRODUCTION

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare autoimmune blood disorder, which presents with microangiopathic hemolytic anemia, thrombocytopenia, and microvascular thrombosis and is caused by severe deficiency of ADAMTS13. iTTP may result in both acute and chronic complications and is rapidly fatal without expedient treatment. Life-time risk of relapse is approximately 40%.

AREAS COVERED

A number of predictors of relapse has been described in the literature. The most well-studied predictor of relapse is persistent ADAMTS13 deficiency; however, it is not a perfect marker. Relapse can be prevented by treatment with immunosuppressive medications, with rituximab being the most studied.

EXPERT OPINION

Patients who recover from iTTP should be regularly assessed, including with ADAMTS13 activity testing. The optimal frequency of assessments has not been established, but every 3 months is recommended. Considering the potential for significant organ damage and mortality associated with iTTP relapse, patients in remission and with persistent ADAMTS13 activity of 10-20% should be prophylactically treated with immunosuppression. Additional markers to precisely identify patients at higher risk of relapse are needed.

Lawrence K, Théberge J, Mandzia J, Barth D, Licht C, Patriquin CJ. Blood-brain barrier permeability in survivors of immune-mediated thrombotic thrombocytopenic purpura: a pilot study

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare, life-threatening disorder of systemic microthrombosis and organ ischemia. The etiology of chronic cerebrovascular outcomes in iTTP survivors is largely unknown. In this pilot study, we measured blood-brain barrier (BBB) permeability in patients with iTTP at the start of remission and 6 months later. This prospective pilot study included 7 adult patients with incident iTTP. Eligibility criteria included ADAMTS13 activity < 10% and detectable inhibitor at diagnosis. Patients were recruited from London Health Sciences Centre in Canada (2017-2019) within 3 days of hospital admission and followed for 6 months after remission (defined as normalization of platelet count and lactate dehydrogenase with no clinical signs or symptoms of microvascular injury for more than 30 days after the last plasma exchange). All patients had cerebral computed tomography perfusion scans with BBB permeability surface product measurements. Patients (5 women, 2 men) had a mean age of 48 years (range, 21-77 years). At diagnosis, patients had a mean platelet count of 22 (standard deviation [SD], 25) × 109/L. At the start of remission, mean BBB permeability surface product was 0.91 (0.30) mL/min/100 g. Six months later, the mean permeability surface product was 0.56 (0.22) mL/min/100 g, with a mean difference of -0.312 mL/min/100 g (95% confidence interval: -0.4729 to -0.1510; P = .0032). In this pilot study of patients with iTTP, pathologically increased BBB permeability was evident, and although there was some improvement, this persisted 6 months after remission. Future work will explore the chronicity of these findings and their clinical implications.

Best practices and recommendations for drug regimens and plasma exchange for immune thrombotic thrombocytopenic purpura

INTRODUCTION

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening thrombotic microangiopathy characterized by microangiopathic hemolytic anemia, thrombocytopenia, and organ injury. TTP pathophysiology is based on a severe ADAMTS13 deficiency, and is a medical emergency with fatal outcome if appropriate treatment is not initiated promptly.

AREAS COVERED

Authors will review the best options currently available to minimize mortality, prevent relapses, and obtain the best clinical response in patients with immune TTP (iTTP). Available bibliography about iTTP treatment has been searched in Library's MEDLINE/PubMed database from January 1990 until April 2021.

EXPERT OPINION

The generalized use of plasma exchange marked a paradigm in the management of iTTP. In recent years, strenuous efforts have been done for a better understanding of the pathophysiology of this disease, improve diagnosis, optimize treatment, reduce mortality, and prevent recurrences. The administration of front-line rituximab and, more recently, the availability of caplacizumab, the first targeted therapy for iTTP, have been steps toward a further reduction in early mortality and for the prevention of relapses.

The standard of care for immune thrombotic thrombocytopenic purpura today

Targeted therapy of immune thrombotic thrombocytopenic purpura (iTTP) requires acurate and prompt diagnosis and differentiation from complement-mediated hemolytic uremic syndrome and other causes of thrombotic microangiopathy. ADAMTS-13 (A Disintegrin And Metalloprotease with ThromboSpondin-1 Domain, member 13) evaluation (activity and inhibitors or anti-ADAMTS-13 IgG) is the key for diagnosis and further management of patients with suspected iTTP during acute episode and in clinical response or remission. Clinical trial results and real-world data have demonstrated the efficacy and safety of the triple therapy consisting of therapeutic plasma exchange, caplacizumab, and immunosuppressives (e.g., corticosteroids and rituximab) for acute iTTP. Such a therapeutic strategy has significantly accelerated the normalization of platelet counts, decreased the length of stays in the intensive care unit and the hospital, but most importantly reduced the mortality rate. The present review highlights some of the important advancements for the diagnosis and management of iTTP and proposes triple therapy as the standard of care for acute iTTP today.

[Treatment of thrombotic thrombocytopenic purpura]

The review discusses approaches to treatment of acquired thrombotic thrombocytopenic purpuгa (aTTP). In patients with aTTP plasma exchanges, glucocorticosteroids allow to stop an acute attack of TTP, and use of rituximab allows to achieve remission. In recent years, caplacizumab has been used. Treatment options such as cyclosporin A, bortezomib, splenectomy, N-acetylcysteine, recombinant ADAMTS13 are also described. Separately discussed issues of management of patients with TTP during pregnancy, and pediatric patients with TTP.