Advances in the management of TTP

Plasmapheresis combined with rituximab treatment of a case of thrombotic thrombocytopenic purpura with Sjögren syndrome and renal impairment: A case report

RATIONALE

Thrombotic thrombocytopenic purpura (TTP) is a rare thrombotic microangiopathy caused by reduced activity of the von Willebrand factor-cleaving protease (ADAMTS13), which can be life-threatening. The patient reported in this case study also had concurrent Sjögren syndrome and renal impairment, presenting multiple symptoms and posing a great challenge in treatment.

PATIENT CONCERNS

A 25-year-old woman in the postpartum period visited the hospital due to indifference in consciousness for more than 1 day following cesarean section 8 days prior.

DIAGNOSIS

Notable decreases were observed in platelets, hemoglobin, creatinine, and ADAMTS13 levels. After a consultative examination by an ophthalmologist, she was diagnosed with retinal hemorrhage in the right eye and dry eye syndrome in both eyes.

INTERVENTIONS

Having been diagnosed with TTP with Sjögren syndrome and renal impairment, she received repeated treatments with plasmapheresis combined with rituximab.

OUTCOMES

Following treatment and during the follow-up period, the patient's platelet counts and bleeding symptoms significantly improved.

LESSONS

TTP has a high mortality rate, and when combined with Sjögren syndrome and renal impairment, it poses an even greater challenge in treatment. However, after administering standard plasmapheresis combined with rituximab treatment, the treatment outcome is favorable.

Impact of allele-selective silencing of von Willebrand factor in mice based on a single nucleotide allelic difference in von Willebrand factor

INTRODUCTION

Von Willebrand factor (VWF) plays a pathophysiological role in hemostatic disorders. Partial inhibition of the VWF gene through small interfering RNA (siRNA)-mediated allele-selective silencing could be a promising therapeutic strategy. For von Willebrand disease, allele-selectively inhibiting dominant-negative VWF-alleles might ameliorate the phenotype. For thrombotic disorders, partial VWF reduction can lower thrombotic risk, while avoiding bleeding. Previously, we demonstrated the feasibility of Vwf-silencing in homozygous C57BL/6J (B6) or 129S1/SvImJ (129S) mice. The present study investigated allele-selective Vwf-silencing in a complex heterozygous setting of crossed B6 and 129S mice and its subsequent hemostatic impact.

MATERIALS AND METHODS

Heterozygous B6.129S mice were treated with siRNAs targeting Vwf expressed from either B6- (siVwf.B6) or 129S-alleles (siVwf.129S). Plasma VWF and lung Vwf mRNA were determined. siVwf.B6-treated B6.129S mice were subjected to ferric chloride-induced mesenteric vessel thrombosis and tail-bleeding.

RESULTS

In B6.129S mice, siVwf.B6 reduced Vwf mRNA of the targeted B6-allele by 72% vs. only 12% of the non-targeted 129S-allele (41% total mRNA reduction), lowering plasma VWF by 46%. Oppositely, siVwf.129S reduced Vwf mRNA by 45%, now selectively inhibiting the 129S-allele over the B6-allele (58% vs. 9%), decreasing plasma VWF by 43%. The allele-selective VWF reduction by siVwf.B6 coincided with decreased thrombus formation in mesenteric arterioles, without prolonging tail-bleeding times.

CONCLUSIONS

This study demonstrates the feasibility of allele-selective Vwf-silencing in a heterozygous setting, achieving a controlled close to 50% reduction of plasma VWF. The observed thromboprotection and absence of prolonged bleeding times underline the potential of allele-selective Vwf-silencing as a therapeutic strategy in hemostatic disorders.

Magnesium sulphate in patients with thrombotic thrombocytopenic purpura (MAGMAT): a randomised, double-blind, superiority trial

PURPOSE

Studies have suggested benefits from magnesium sulphate in thrombotic thrombocytopenic purpura (TTP). We aimed to measure the effects of magnesium sulphate supplementation on TTP recovery.

METHODS

In this multicenter, randomised, double-blind, controlled, superiority study, we enrolled adults with a clinical diagnosis of TTP. Patients were randomly allocated to receive magnesium sulphate (6 g intravenously followed by a continuous infusion of 6 g/24 h for 3 days) or placebo, in addition to the standard treatment. The primary outcome was the median time to platelet normalisation (defined as a platelet count ≥ 150 G/L). Efficacy and safety were assessed by intention-to-treat.

RESULTS

Overall, we enrolled 74 participants, including one who withdrew his/her consent. Seventy-three patients were further analyzed, 35 (48%) allocated to magnesium sulphate and 38 (52%) to placebo. The median time to platelet normalisation was 4 days (95% confidence interval [CI], 3-4) in the magnesium sulphate group and 4 days (95% CI 3-5) in the placebo group. The cause-specific hazard ratio of response was 0.93 (95% CI 0.58-1.48, p = 0.75). The number of patients with ≥ 1 serious adverse reactions was similar in the two groups. By day 90, four patients in the magnesium sulphate group and two patients in the placebo group had died (p = 0.42). The most frequent adverse event was low blood pressure occurring in 34% in the magnesium sulphate group and 29% in the placebo group (p = 0.80).

CONCLUSION

Among patients with TTP, the addition of magnesium sulphate to the standard of care did not result in a significant improvement in time to platelet normalisation.

Cerebral venous thrombosis in patients with autoimmune disease, hematonosis or coronavirus disease 2019: Many familiar faces and some strangers

BACKGROUND

Cerebral venous thrombosis, a rare stroke, is characterized by neurological dysfunction caused by bleeding and/or infarction resulting from venous sinus thrombosis, the so-called venous stroke. Current guidelines recommend anticoagulants as first-line therapy in the treatment of venous stroke. With complicated causes of cerebral venous thrombosis, treatment is difficult, especially when combined with autoimmune diseases, blood diseases, and even COVID-19.

AIMS

This review summarizes the pathophysiological mechanisms, epidemiology, diagnosis, treatment, and clinical prognosis of cerebral venous thrombosis combined with autoimmune diseases, blood diseases, or infectious diseases such as COVID-19.

CONCLUSION

A systematic understanding of particular risk factors that should not be neglected when unconventional cerebral venous thrombosis occurs and for a scientific understanding of pathophysiological mechanisms, clinical diagnosis, and treatment, thus contributing to knowledge on special types of venous stroke.

Measuring ADAMTS-13 activity to diagnose thrombotic thrombocytopenic purpura: a novel, fast fiber-optic surface plasmon resonance immunoassay

Background

Thrombotic thrombocytopenic purpura (TTP) is characterized by severe ADAMTS-13 activity deficiency (<10%). Diagnostic testing is challenging because of unavailability, high cost, and expert technician requirement of ADAMTS-13 enzyme assays. Cost-effective, automated fiber-optic surface plasmon resonance (FO-SPR) platforms show potential for developing diagnostic tests. Yet, FO-SPR has never been explored to measure enzymatic activities.

Objectives

To develop an easy-to-use ADAMTS-13 activity assay utilizing optical fibers to rapidly diagnose TTP.

Methods

The ADAMTS-13 activity assay was designed and optimized using FO-SPR technology based on a previously described enzyme-linked immunosorbent assay setup. A calibration curve was generated to quantify ADAMTS-13 activity in plasma of healthy donors and patients with acute immune-mediated TTP (iTTP), hemolytic uremic syndrome, or sepsis. ADAMTS-13 activity data from FO-SPR and fluorescence resonance energy transfer-based strategies (FRETS)-VWF73 reference assays were compared.

Results

After initial assay development, optimization improved read-out magnitude and signal-to-noise ratio and reduced variation. Further characterization demonstrated a detection limit (6.8%) and inter-assay variation (Coefficient of variation, 7.2%) that showed good analytical sensitivity and repeatability. From diverse plasma samples, only plasma from patients with acute iTTP showed ADAMTS-13 activities below 10%. Strong Pearson correlation (r = 0.854) between FO-SPR and reference FRETS-VWF73 assays were observed for all measured samples.

Conclusions

A fast ADAMTS-13 activity assay was designed onto automated FO-SPR technology. Optimization resulted in sensitive ADAMTS-13 activity measurements with a detection limit enabling clinical diagnosis of TTP within 3 hours. The FO-SPR assay proved strong correlation with the reference FRETS-VWF73 assay. For the first time, this assay demonstrated the capacity of FO-SPR technology to measure enzymatic activity in pre-clinical context.

Global Health Resource Utilization and Cost-Effectiveness of Therapeutics and Diagnostics in Immune Thrombotic Thrombocytopenic Purpura (TTP)

In this review, we examine the current landscape of health resource utilization and cost-effectiveness data in the care of patient populations with immune thrombotic thrombocytopenic purpura. We focus on the therapeutic (therapeutic plasma exchange, glucocorticoids, rituximab, caplacizumab) and diagnostic (ADAMTS13 assay) health technologies employed in the care of patients with this rare disease. Health resource utilization and cost-effectiveness data are limited to the high-income country context. Measurement of TTP-specific utility weights in the high-income country context and collection of health resource utilization data in the low- and middle-income country settings would enable an evaluation of country-specific quality-adjusted life expectancy and cost-effectiveness of these therapeutic and diagnostic health technologies. This quantification of value is one way to mitigate cost concerns where they exist.

HUS and TTP: traversing the disease and the age spectrum

Hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenia purpura (TTP) are rare diseases sharing a common pathological feature, thrombotic microangiopathy (TMA). TMA is characterized by microvascular thrombosis with consequent thrombocytopenia, microangiopathic hemolytic anemia and/or multiorgan dysfunction. In the past, the distinction between HUS and TTP was predominantly based on clinical grounds. However, clinical presentation of the two syndromes often overlaps and, the differential diagnosis is broad. Identification of underlying pathogenic mechanisms has enabled the classification of these syndromes on a molecular basis: typical HUS caused by Shiga toxin-producing Escherichia coli (STEC-HUS); atypical HUS or complement-mediated TMA (aHUS/CM-TMA) associated with genetic or acquired defects leading to dysregulation of the alternative pathway (AP) of complement; and TTP that results from a severe deficiency of the von Willebrand Factor (VWF)-cleaving protease, ADAMTS13. The etiology of TMA differs between pediatric and adult patients. Childhood TMA is chiefly caused by STEC-HUS, followed by CM-TMA and pneumococcal HUS (Sp-HUS). Rare conditions such as congenital TTP (cTTP), vitamin B12 metabolism defects, and coagulation disorders (diacylglycerol epsilon mutation) present as TMA chiefly in children under 2 years of age. In contrast secondary causes and acquired ADAMT13 deficiency are more common in adults. In adults, compared to children, diagnostic delays are more frequent due to the wide range of differential diagnoses. In this review we focus on the three major forms of TMA, STEC-HUS, aHUS and TTP, outlining the clinical presentation, diagnosis and management of the affected patients, to help highlight the salient features and the differences between adult and pediatric patients which are relevant for management.

N-Acetylcistein for thrombotic thrombocytopenic purpura: an observational case series study

Acquired thrombotic thrombocytopenic purpura (TTP) is a life-threatening disorder. N-Acetylcysteine (NAC) rapidly degrades ultra-large von Willebrand factor multimers by disrupting the disulfide bonds. We report a series of twelve consecutive patients diagnosed with acquired TTP successfully treated with high-dose NAC (150 mg/kg/day) in combination with plasma exchange and steroids. Eight patients also received rituximab. Two patients presented refractory TTP. All patients achieved a quick clinical response in a median time of 5.5 days after starting NAC and are alive after a median follow-up of 29 months. The treatment was feasible and well tolerated. These data provide further evidence of the potential benefit and safety of adding NAC to the standard of care.

Single-domain antibody-based noninvasive in vivo imaging of α-synuclein or tau pathology

Intracellular deposition of α-synuclein and tau are hallmarks of synucleinopathies and tauopathies, respectively. Recently, several dye-based imaging probes with selectivity for tau aggregates have been developed, but suitable imaging biomarkers for synucleinopathies are still unavailable. Detection of both of these aggregates early in the disease process may allow for prophylactic therapies before functional impairments have manifested, highlighting the importance of developing specific imaging probes for these lesions. In contrast to the β sheet dyes, single-domain antibodies, found in camelids and a few other species, are highly specific, and their small size allows better brain entry and distribution than whole antibodies. Here, we have developed such imaging ligands via phage display libraries derived from llamas immunized with α-synuclein and tau preparations, respectively. These probes allow noninvasive and specific in vivo imaging of α-synuclein versus tau pathology in mice, with the brain signal correlating strongly with lesion burden. These small antibody derivatives have great potential for in vivo diagnosis of these diseases.

How I diagnose and treat atypical hemolytic uremic syndrome

Our understanding and management of atypical hemolytic uremic syndrome (aHUS) have dramatically improved in the last decade. aHUS has been established as a prototypic disease resulting from a dysregulation of the complement alternative C3 convertase. Subsequently, prospective nonrandomized studies and retrospective series have shown the efficacy of C5 blockade in the treatment of this devastating disease. C5 blockade has become the cornerstone of the treatment of aHUS. This therapeutic breakthrough has been dulled by persistent difficulties in the positive diagnosis of aHUS, and the latter remains, to date, a diagnosis by exclusion. Furthermore, the precise spectrum of complement-mediated renal thrombotic microangiopathy is still a matter of debate. Nevertheless, long-term management of aHUS is increasingly individualized and lifelong C5 blockade is no longer a paradigm that applies to all patients with this disease. The potential benefit of complement blockade in other forms of HUS, notably secondary HUS, remains uncertain.

[Autoimmune diagnostics in nephrology and rheumatology]

Autoimmune diagnostics plays a central role in the detection of various acute and/or chronic diseases in both nephrology and rheumatology, which are associated with high morbidity and mortality if left untreated or not detected in time. Patients are threatened with significant limitations in everyday skills and quality of life due to loss of kidney function and dialysis, immobilizing and destructive joint processes or also significant damage of organ systems. In all of these autoimmune diseases, early diagnosis and treatment is of central importance for the further course and prognosis of disease.Antibodies play an essential role in the pathogenesis of autoimmune diseases. Antibodies are either directed against organ or tissue-specific antigens, such as in primary membranous glomerulonephritis or Goodpasture's syndrome, or they lead to a systemic disease such as systemic lupus erythematosus (SLE) or rheumatoid arthritis.Knowledge of the sensitivity and specificity of antibodies is crucial for the interpretation of antibody diagnostics results. Antibody detection can precede the clinical onset of the disease, and antibody titers often reflect disease activity. However, there are also false positive results. Detection of antibodies in the absence of disease symptoms often leads to uncertainty and unnecessary further diagnostics. Therefore, an unfounded "antibody screening" is not recommended.A rational antibody diagnostics is an integral part of the diagnostics and during treatment of nephrological and rheumatological diseases like glomerulonephrititis, pulmorenal syndrome, SLE and other collagenosis, thrombotic microangiopathy (HUS/TTP) and rheumatoid arthritis.

Comparison of clinical characteristics of first-episode thrombotic thrombocytopenic purpura and TTP-like syndrome: a retrospective cohort study in a level I hematology center in China

Comparing the characteristics of thrombotic thrombocytopenic purpura (TTP) and TTP-like syndrome patients at admission will allow early differentiation of TTP from TTP-like syndrome and help tailor initial treatment. The medical records of 78 patients with suspected TTP in the Emergency Department of Peking University People's Hospital in the past 5 years were retrospectively analyzed and divided into TTP and TTP-like syndrome groups based on ADAMTS13 activity and ADAMTS13 antibody titer. There were 25 and 53 patients in the TTP group and the TTP-like syndrome group, respectively. The neutrophil-to-lymphocyte ratio (P = 0.025) was tremendously higher, and albumin (P = 0.002) was lower in the TTP-like syndrome group, indicating a more severe inflammation. Compared with the TTP-like syndrome group, the TTP group had an approximately two-fold to three-fold higher prevalence of central nervous system dysfunction (P < 0.001). Also, hemolysis was more substantial in the TTP group as evidenced by higher schistocytes (P < 0.001), reticulocyte (P < 0.001), total bilirubin (P = 0.002), indirect bilirubin (P < 0.001), lactate dehydrogenase (P = 0.007) and cell-free hemoglobin (P < 0.001), simultaneously lower platelet (P < 0.001), haptoglobin (P = 0.044), and ADAMTS13 activity (P < 0.001). The Kaplan-Meier survival analysis showed that the TTP group significantly predicted poor prognosis (log-rank test: X² = 5.368, P = 0.021). TTP and TTP-like syndrome are two kinds of distinct phenotypes with different hemolysis statuses and illustrated differentiated inflammatory reactions, target organ damage (TOD), and the clinical outcome.

Prognostic value of dynamic cardiac biomarkers in patients with acquired refractory thrombocytopenic purpura: A retrospective study in Chinese population

Introduction

Thrombotic thrombocytopenic purpura (TTP) is becoming a curable disease with the introduction of therapeutic plasma exchange (TPE). However, cardiovascular complications remain essential causes of mortality in patients with refractory TTP, while the association of cardiac biomarkers with the prognosis of TTP warrants further investigation.

Methods

Patients admitted to the First Affiliated Hospital of Soochow University for refractory TTP from 2013 through 2020 were included in this retrospective study. Clinical characteristics were collected from electronic health records. Biomarker levels on admission and post TPE were recorded. Logistic regression was adopted to identify risk factors for mortality.

Results

A total of 78 patients with refractory TTP were included in this study. Twenty‐one patients died during hospitalization, with a mortality rate of 26.9%. High‐sensitivity cardiac troponin T (hs‐cTnT), N‐terminal probrain natriuretic peptide (NT‐proBNP), and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ratios (AAR) were increased in deceased patients compared with the survival group. Multivariate analysis showed that AAR after TPE was associated with overall mortality (OR: 4.45, 95% CI 1.09–18.19). The areas under the receiver operator characteristic curve (AUC) of AAR, hs‐cTnT, and NT‐proBNP for the association with mortality were 0.814, 0.840, and 0.829, respectively.

Conclusion

Higher post‐TPE cardiac biomarker levels are associated with increased in‐hospital mortality in patients with refractory TTP.

How to approach haemolysis: Haemolytic anaemia for the general physician

Haemolytic anaemia can seem like a complicated topic. The constellation of reticulocytosis, increased lactate dehydrogenase levels, increased unconjugated bilirubin levels and decreased haptoglobin levels should prompt general physicians to consider haemolysis as a differential diagnosis. When further approaching haemolytic anaemia, subdividing patients into those who are 'direct antiglobulin test (DAT) positive' (immune) or 'DAT negative' (non-immune) is a simple and clinically relevant way to start to formulate a cause for the haemolytic anaemia. Immune causes of haemolytic anaemia include autoimmune haemolytic anaemia, drugs and delayed haemolytic transfusion reactions. Non-immune causes include the haemoglobinopathies (such as sickle cell disease) and microangiopathic haemolytic anaemias (such as disseminated intravascular coagulation). Early supportive care in haemolytic anaemia is important and may involve blood transfusions as well as interventions to slow the rate of haemolysis, such as steroids in autoimmune haemolytic anaemia. Complications of haemolysis include pigment gallstones, high-output cardiac failure and thromboembolism. Haemolytic anaemia should be referred to the haematologist for further investigation, however, the recognition and early management by the general physician is imperative in improving the patient's outcome.