Thrombotic Thrombocytopenic Purpura: Pathophysiology, Diagnosis, and Management

Investigating the dual causative pathways linking immune cells and venous thromboembolism via Mendelian randomization analysis

BACKGROUND

Venous thromboembolism (VTE) is a common vascular disease with a significant global burden, influenced by multiple factors, such as genetic, environmental, and immune components. Immune responses and shifts in immune cell profiles are closely linked to the development and progression of VTE, yet current studies are limited by confounding factors and reverse causation. To address these limitations, this study uses Mendelian randomization to explore the causal relationship between immune cell traits and VTE, aiming to provide insights into underlying mechanisms.

METHODS

We utilized GWAS data on 731 immunological traits (n = 3757) from the IEU OpenGWAS project and VTE (21021 cases, 391160 controls) from Finngen public data. Five commonly used Mendelian randomization (MR) methods were employed, including inverse-variance weighted (IVW), MR-Egger regression, weighted median estimator (WME), and both weighted and simple models to analyze their associations. Sensitivity checks for the results included pleiotropy tests, heterogeneity tests, and leave-one-out analyses.

RESULTS

From a strictly statistical perspective, no significant associations were observed after FDR correction. However, our exploratory analysis suggested potential trends between immune cell traits and VTE. When immune cells were considered as the exposure and VTE as the outcome, 44 immune cell traits were suggestively associated with VTE based on uncorrected p-values. Conversely, when VTE was considered as the exposure, it appeared to influence immune cell traits. Specifically, secreting CD4 regulatory T cells (OR = 0.9084; 95% CI: 0.8418-0.9804; P = 0.0135; FDR = 0.7339) and activated and resting CD4 regulatory T cells (OR = 0.9275; 95% CI: 0.8622-0.9977; P = 0.0433; FDR = 0.8048) suggested a potential protective trend against VTE. On the other hand, B cells expressing CD20 (OR = 1.0697; 95% CI: 1.0227-1.1188; P = 0.0033; FDR = 0.5767) and myeloid cells expressing CD33 (OR = 1.0199; 95% CI: 1.0021-1.0382; P = 0.0296; FDR = 0.7339) may be linked to an increased risk of VTE.

CONCLUSIONS

From a strict statistical perspective, no significant associations were identified after FDR correction. However, our analysis using MR method suggests a potential link between VTE and immune cell traits, suggesting the complex interplay between the immune system and thrombotic events. While this study is exploratory and needs validation, the findings of this study are hypothesis-generating with resect to the mechanisms underlying VTE and encourage further investigation into the role of immune activity in VTE pathology.

Malignant hypertension induces thrombotic microangiopathy and renal failure: A case report

RATIONALE

Thrombotic microangiopathies (TMA) caused by malignant hypertension is an acute and critical disease among rare diseases. Although renal biopsy pathology is a golden indicator for diagnosing kidney disease, it cannot distinguish between primary and secondary TMA and requires a comprehensive diagnosis in conjunction with other laboratory tests and medical history.

PATIENT CONCERNS

A 33-year-old young man was hospitalized due to unexplained kidney failure.

DIAGNOSIS

A young man was admitted to the hospital with unexplained renal failure with severe heart failure and was diagnosed with TMA by renal biopsy. Further investigation excludes primary TMA and is considered to be due to malignant hypertension.

INTERVENTIONS

Temporary hemodialysis combined with aggressive blood pressure control and the use of angiotensin receptor-neprilysin inhibitor are the primary management approach.

OUTCOMES

Upon discharge, the patient had ceased dialysis and showed significant renal function recovery. After 1 year follow-up period, creatinine levels remained stable at 2.373 mg/dL, while lactate dehydrogenase, B-type natriuretic peptide, and platelet levels all returned to within normal ranges.

LESSONS

TMA caused by malignant hypertension is rare and similar to the clinical manifestations of TMA caused by Thrombotic Thrombocytopenic Purpura and Hemolytic Uremic Syndrome, but it is often sudden and critical. Early identification and diagnosis and aggressive antihypertensive therapy, must be given to avoid end-stage renal disease, long-term maintenance of dialysis, and the financial burden of unnecessary plasmapheresis and potential side effects of glucocorticoids.

[Thrombopenia and hemolytic anemia in acute and emergency medicine : Detailed view at thrombotic microangiopathies]

Recognizing anemia and thrombpenia in acute and emergency medicine is easy. Acute (microangiopathic hemolytic) anemia and thrombopenia can be a sign of thrombotic microangiopathy (TMA). TMA syndromes are potentially life-threatening diseases. Diagnosing a TMA syndrome, causal differentiation and treatment require specialist knowledge that is not always available in acute and emergency medicine. Many differential diagnoses and examinations are usually necessary to make a correct diagnosis. Therefore, a standardized diagnostic algorithm is helpful for early diagnosis and treatment initiation.

Incidental neutropenia: An emergency medicine focused approach

INTRODUCTION

Neutropenia is defined as an absolute neutrophil count (ANC) < 1500 cells/microL and may be discovered incidentally in an asymptomatic, afebrile patient.

OBJECTIVE

This narrative review provides an approach to the afebrile emergency department patient with incidental neutropenia.

DISCUSSION

Neutropenia is an ANC < 1500 cells/microL, with mild neutropenia defined as an ANC ≥ 1000 to <1500 cells/microL, moderate ≥500 to <1000 cells/microL, severe <500 cells/microL, and agranulocytosis <200 cells/microL. Incidental or isolated neutropenia is an ANC < 1500 cells/microL discovered on laboratory testing unrelated to the patient's chief complaint (e.g., chest pain, abdominal pain, shortness of breath, etc.) and not associated with fever or infectious signs and symptoms. There are a variety of etiologies, with inherited forms, dose-dependent drug-induced neutropenia, and infections the most common causes. Testing includes complete blood count with differential and peripheral smear. Management is based on the patient's hemodynamic status, presence of fever, severity of neutropenia, and the peripheral smear. Patients who are critically ill, febrile, have severe neutropenia, or have a concerning peripheral smear (schistocytes, atypical lymphocytes) should undergo hematology consultation. Those with critical illness or fever with neutropenia should receive broad-spectrum antibiotics. Patients who are afebrile, hemodynamically stable, and non-toxic appearing with mild or moderate neutropenia can likely be discharged for repeat testing in one to two weeks.

CONCLUSION

Understanding the approach to incidental neutropenia can improve patient care. Critically ill or febrile patients should be admitted, but select patients may be discharged.

Clinical and economic burden of suspected thrombotic thrombocytopenic purpura in US hospitals

PURPOSE

Severe ADAMTS13 deficiency (activity <10%) is the diagnostic threshold for thrombotic thrombocytopenic purpura (TTP) and is associated with various clinical symptoms, abnormal laboratory results, and long-term complications.

METHODS

This retrospective, noninterventional cohort study used the Premier Healthcare Database to identify patients with ADAMTS13 activity of <10% in US hospitals from January 1, 2016, through March 31, 2020. The objective was to describe patient characteristics, laboratory results, comorbidities (as measured by the Elixhauser comorbidity index), symptoms, length of stay, treatment patterns, mortality, inpatient costs, and readmission rates (summarized descriptively). Inpatient costs were calculated as total cost to the hospital.

RESULTS

There were 211 patients with severe ADAMTS13 deficiency; 89% of patients had a TTP-related diagnosis, of whom 62% had a primary diagnosis of thrombotic microangiopathy. Over 80% of patients with available data had a decreased platelet count and elevated lactate dehydrogenase; schistocytes were detected in 99%. The most prevalent symptoms/complications were neurological, bleeding, and pain. Most patients (86%) had 2 or more Elixhauser comorbidities. Over 80% of patients received 1 or more TTP-related treatments, mostly plasma exchange. The mean length of stay was 11.5 days; 5% of patients died during their stay. Readmission rates at 30, 60, and 90 days were 20%, 26%, and 28%, respectively. The median (interquartile range) total inpatient cost to the hospital throughout the index admission was $33,221 ($19,431-$64,901).

CONCLUSION

Patients with severe ADAMTS13 deficiency have substantial clinical burden, have high mortality and readmission rates, and generate high costs for hospitals. There is a high need for a therapy that replaces ADAMTS13, thus addressing the root cause of the symptoms and complications caused by this deficiency.

Thrombotic Thrombocytopenic Purpura Masked by Severe Preeclampsia: A Case Report

Thrombotic thrombocytopenic purpura (TTP) is an exceptionally rare complication during pregnancy and even rarer when it coincides with severe preeclampsia in the same index pregnancy. We report the case of a 36-year-old female who presented with confusion at 38 weeks of gestation. Although her signs and symptoms strongly suggested severe preeclampsia, she was expected to make a full recovery after an emergency C-section. However, her failure to recover and persistent deterioration indicated the need for further investigations into the cause. Once her blood smear showed fragmented cells, plasma exchange treatment was initiated immediately without waiting for the results of the ADAMST13 activity test, which later showed almost undetectable levels. Ultimately, the patient achieved a full recovery, and her platelet count as well as ADAMST13 levels continued to improve upon 12 weeks of follow-up with no further treatment needed. Proper clinical judgment and a cooperative multidisciplinary team were key elements in managing this case.

Hemorrhagic stroke in children

Hemorrhagic stroke (HS) in childhood accounts for almost 50% of childhood strokes, is among the top ten causes of deaths, or determines lifelong disability. These facts form significant socio-economic and demographic problems. The purpose of this review is to analyze current knowledge about HS in children. The data on HS terminology are presented, taking into account the International Classification of Diseases 11 edition. Attention is paid to the epidemiology of HS in children, including the results of individual local studies. The risk factors of HS in children were studied with an analysis of the causal, pathophysiological mechanisms of HS of various etiologies. The ideas about the clinical manifestations of HS in children are described. The analysis of HS treatment in children was carried out with an emphasis on achievements in neurointensive therapy of the acute period of HS. This review also includes information on the outcomes of HS in children.

Complex immunogenicity assessment in caplacizumab-treated patients with immune-mediated thrombotic thrombocytopenic purpura who have received plasma exchange

Background

International Society on Thrombosis and Haemostasis guidelines for immune-mediated thrombotic thrombocytopenic purpura (iTTP) treatment recommend concurrent therapeutic plasma exchange (TPE), immunosuppressive therapy (IST), and caplacizumab. TPE can complicate antidrug antibody (ADA) measurements by transferring pre-existing antibodies (pre-Abs) into patients via donor plasma and/or diluting treatment-emergent (TE) ADAs.

Objectives

To assess the presence of ADAs in patients with iTTP who received caplacizumab.

Methods

Immunogenicity data from patients with iTTP receiving caplacizumab once daily plus TPE/immunosuppressive therapy in 4 clinical trials (TITAN, HERCULES, Post-HERCULES, and a trial conducted in Japanese patients) in the clinical development program were analyzed. ADA and modified ADA assays differentiated pre-Abs from TE ADAs. A functional neutralizing antibody (NAb) assay and a neutralizing epitope characterization assay (NECA) assessed the presence of ADAs with neutralizing potential. The impact of ADAs on efficacy, pharmacokinetics/pharmacodynamics, and safety was evaluated.

Results

Among 228 patients in 4 studies, prevalence of pre-Abs ranged from 17.1% (TITAN) to 56.7% (HERCULES), while TE ADA prevalence ranged from 3.1% (HERCULES) to 14.3% (Japanese study). The TE NAb-positive rate ranged from 0% (Japanese study) to 12% (Post-HERCULES) using the functional NAb assay and from 2.7% (Post- HERCULES) to 14.3% (Japanese study) using the NECA. The presence of these antibodies did not impact treatment efficacy or safety.

Conclusion

A complex immunogenicity assay strategy was required to define the pre-Ab/TE ADA status of patients with iTTP treated with caplacizumab in a clinical trial setting. In addition to the wide range of pre-Abs observed, few patients had detectable TE ADAs or NAbs, neither of which affected efficacy/safety.

Microangiopathic thrombocytopenia caused by vitamin B12 deficiency responding to plasma exchange

A young adult African American female presented with normocytic microangiopathic haemolytic anaemia, elevated lactate dehydrogenase and thrombocytopenia. The patient responded to therapeutic plasma exchanges (TPE) for presumed thrombotic microangiopathy caused by thrombotic thrombocytopenic purpura (TTP). After relapsing, the patient was found to have pancytopenia, megaloblastic bone marrow and low vitamin B12 consistent with pernicious anaemia, which improved with intramuscular B12 and discontinuation of TPE. B12-deficient macrocytosis was not seen at presentation due to concomitant alpha-thalassaemia. Initial clinical/laboratory improvement is attributed to B12 present in TPE plasma. B12 deficiency can mimic TTP. Vigilance is needed regarding atypical presentations of pernicious anaemia.

Clinical Profile, Treatment and Outcome of Thrombotic Thrombocytopenia Purpura (TTP) in Rituximab Era- an Experience from Tertiary Care Centre from North India

Thrombotic thrombocytopenic purpura (TTP) is a microangiopathic hemolytic anemia (MAHA) resulting from severe deficiency of ADAMTS13. TTP is an acute medical emergency which requires early treatment with therapeutic plasma exchange. With the early use of Rituximab along with PLEX, early response is achieved and relapse rate has gone down. There is lack of published data from India regarding treatment and outcome of TTP. We retrospectively analyzed our data of 21 patients of TTP including 4 patients who had TA-TMA. TTP patients were treated with TPE, pulse methylprednisolone and rituximab. After a median follow up of 57.5 months overall survival in TTP patients was 82.3% in our study and one patient relapsed twice but again responded to same treatment. Relapse free survival was 92.8%. The mortality rate in our study in TTP patients was (3/17) 17.6%. The total response rate was 82.3% (14/17). Out of 4 patients of TA-TMA, Only 33.3% patients responded to plasma exchange in TA-TMA while two patients died (2/4) 50%. Immediate TPE and early rituximab are associated with improved survival in TTP patients, however TA-TMA still remains a significant challenge for transplant physicians and more research is needed in guiding the therapy.

Capnocytophaga canimorsus Septicemia With Sepsis-Induced Coagulopathy and Endocarditis

Capnocytophaga canimorsus is a rare cause of serious infections with a high mortality of 10% to 30%. It is usually found in the oral cavity of cats and dogs and can cause severe sepsis in immunocompromised patients. An 81-year-old female Caucasian patient presented with C. canimorsus sepsis after a dog bite in her finger three days before presentation to our emergency department. She initially was presented to us with sepsis, thrombopenia, and schistocytes in her laboratory findings, suggesting the differential diagnoses of the multiple subtypes of thrombotic microangiopathy. She was admitted to the medical intensive care unit of the University Hospital of Saarland because of septic shock with circulatory insufficiency. The patient received plasmapheresis, antibiotics, and dialysis, under which she improved significantly. The fingertip of the affected finger developed necrosis and had to be amputated. Furthermore, the patient was diagnosed with a mitral valve endocarditis, a very rare complication of C. canimorsus infection. It was treated conservatively with antibiotics and was no longer detectable 8 weeks after the diagnosis. Surgical intervention was not needed. The case describes well that it is still difficult to distinguish between thrombotic thrombocytopenic purpura (TTP), disseminated intravascular coagulation (DIC), and sepsis-induced coagulopathy (SIC), especially in the early phases of acute disease, especially in C. canimorsus-induced sepsis.

Anti-Inflammatory Cytokine Profiles in Thrombotic Thrombocytopenic Purpura-Differences Compared to COVID-19

Thromboinflammation/immunothrombosis plays a role in several diseases including thrombotic thrombocytopenic purpura (TTP) and COVID-19. Unlike the extensive research that has been conducted on COVID-19 cytokine storms, the baseline and acute phase cytokine profiles of TTP are poorly characterized. Moreover, we compared the cytokine profiles of TTP and COVID-19 to identify the disease-specific/general characteristics of thromboinflammation/immunothrombosis. Plasma concentrations of 33 soluble mediators (SMs: cytokines, chemokines, soluble receptors, and growth factors) were measured by multiplex bead-based LEGENDplex™ immunoassay from 32 COVID-19 patients (32 non-vaccinated patients in three severity groups), 32 TTP patients (remission/acute phase pairs of 16 patients), and 15 control samples. Mainly, the levels of innate immunity-related SMs changed in both diseases. In TTP, ten SMs decreased in both remission and acute phases compared to the control, one decreased, and two increased only in the acute phase compared to remission, indicating mostly anti-inflammatory changes. In COVID-19, ten pro-inflammatory SMs increased, whereas one decreased with increasing severity compared to the control. In severe COVID-19, sixteen SMs exceeded acute TTP levels, with only one higher in TTP. PCA identified CXCL10, IL-1RA, and VEGF as the main discriminators among their cytokine profiles. The innate immune response is altered in both diseases. The cytokine profile of TTP suggests a distinct pathomechanism from COVID-19 and supports referring to TTP as thromboinflammatory rather than immunothrombotic, emphasizing thrombosis over inflammation as the driving force of the acute phase.

The Phenomenon of Thrombotic Microangiopathy in Cancer Patients

Thrombotic microangiopathy (TMA) encompasses a range of disorders characterized by blood clotting in small blood vessels, leading to organ damage. It can manifest as various syndromes, including thrombotic thrombocytopenic purpura (TTP), hemolytic-uremic syndrome (HUS), and others, each with distinct causes and pathophysiology. Thrombo-inflammation plays a significant role in TMA pathogenesis: inflammatory mediators induce endothelial injury and activation of platelet and coagulation cascade, contributing to microvascular thrombosis. Primary TMA, such as TTP, is primarily caused by deficient ADAMTS13 metalloproteinase activity, either due to antibody-mediated inhibition or intrinsic enzyme synthesis defects. In cancer patients, a significant reduction in ADAMTS13 levels and a corresponding increase in VWF levels is observed. Chemotherapy further decreased ADAMTS13 levels and increased VWF levels, leading to an elevated VWF/ADAMTS13 ratio and increased thrombotic risk. Drug-induced TMA (DITMA) can result from immune-mediated or non-immune-mediated mechanisms. Severe cases of COVID-19 may lead to a convergence of syndromes, including disseminated intravascular coagulation (DIC), systemic inflammatory response syndrome (SIRS), and TMA. Treatment of TMA involves identifying the underlying cause, implementing therapies to inhibit complement activation, and providing supportive care to manage complications. Plasmapheresis may be beneficial in conditions like TTP. Prompt diagnosis and treatment are crucial to prevent serious complications and improve outcomes.

Pulmonary Tuberculosis Complicated by Thrombotic Thrombocytopenic Purpura: A Case Report and Literature Review

Thrombotic thrombocytopenic purpura is a rare but life-threatening emergency. Tuberculosis can have hematologic complications. However, concurrent tuberculosis and thrombotic thrombocytopenic purpura are extremely rare. In this study, we report a 53-year-old man who was initially treated for pulmonary tuberculosis but later developed weakness and an altered mental status. Laboratory tests revealed evidence of thrombocytopenia, acute renal insufficiency, and microangiopathic hemolytic anemia. Brain imaging identified intracranial hemorrhage. Further testing revealed low ADAMTS13 activity (1.8%) and positive anti-ADAMTS13 antibody, confirming the diagnosis of thrombotic thrombocytopenic purpura. The patient had a full recovery after anti-tuberculosis treatment, plasma exchange, and supportive care. We present this rare case and review previous relevant studies to remind clinicians about the potential connections between tuberculosis and thrombotic thrombocytopenic purpura. In patients with signs of severe thrombocytopenia and microangiopathic hemolysis, necessary diagnostic tests should be performed to eliminate the possibility of thrombotic thrombocytopenic purpura occurring concurrently with tuberculosis.

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.

Frontline use of rituximab may prevent ADAMTS13 inhibitor boosting during caplacizumab treatment in patients with iTTP: post hoc analysis of a phase 2/3 study in Japan

BACKGROUND

A recent Phase 2/3 study in Japanese patients showed that caplacizumab was effective in treating immune-mediated thrombotic thrombocytopenic purpura (iTTP), with a low rate of iTTP recurrence. ADAMTS13 activity is monitored weekly during caplacizumab treatment to guide discontinuation of caplacizumab and consequently avoid exacerbations or relapse. The aim of this study was to assess changes in ADAMTS13 activity/inhibitor levels during caplacizumab treatment in this patient population.

METHODS

A post hoc analysis of the Phase 2/3 study in Japanese patients was conducted. Patients ≥ 18 years old with confirmed iTTP received 10 mg of caplacizumab daily in conjunction with therapeutic plasma exchange (TPE) and immunosuppression for 30 days post-TPE. Outcomes included time to recovery of ADAMTS13 activity, ADAMTS13 activity level at treatment end, incidence of ADAMTS13 inhibitor re-elevation (ie, inhibitor boosting) during treatment, time to platelet count recovery, number of days of TPE, and safety. Outcomes according to presence of inhibitor boosting were also assessed.

RESULTS

Nineteen patients had confirmed iTTP and were included in this analysis. Median (95% confidence interval) time to recovery of ADAMTS13 activity to ≥ 10%, ≥ 20%, and ≥ 60% was 14.6 (5.9-24.8), 18.5 (5.9-31.8), and 47.5 (18.5-60.9) days, respectively. Median (range) ADAMTS13 activity level at caplacizumab treatment end was 62.0% (29.0-101.0). Nine patients had ADAMTS13 inhibitor boosting. Delayed response of ADAMTS13 activity was observed in patients with inhibitor boosting. The median time to platelet count response and median number of TPE days were shorter in patients with inhibitor boosting compared with patients without inhibitor boosting. Rituximab was administered to almost all patients with inhibitor boosting (88.9%), after completion of TPE. Patients without inhibitor boosting who were treated with rituximab received it prior to completion of TPE. Only one patient experienced a recurrence, which occurred shortly after caplacizumab discontinuation due to an adverse event.

CONCLUSIONS

In patients with iTTP, caplacizumab with TPE and immunosuppression may reduce the risk of ADAMTS13 inhibitor boosting if rituximab is administered early in the iTTP treatment period. Early administration of rituximab in addition to caplacizumab may prevent iTTP recurrence with inhibitor boosting.

TRIAL REGISTRATION

NCT04074187.

Refractory Thrombotic Thrombocytopenic Purpura in a Patient With Triple X Syndrome

Clinical manifestations of triple X syndrome (karyotype 47, XXX) can include autoimmune diseases. We describe the occurrence of acquired thrombotic thrombocytopenic purpura (TTP), an autoimmune condition, refractory to plasmapheresis and rituximab in a patient with triple X syndrome who required vincristine administration for disease remission. To our knowledge, this rare coexistence is the first of its kind reported in Brazil.

Diagnostic Challenges in a Case of Immune-Mediated Thrombotic Thrombocytopenic Purpura With Severe ADAMTS13 Deficiency

Thrombotic Thrombocytopenic Purpura (TTP) is rare and potentially life-threatening thrombotic microangiopathy (TMA) caused by acquired immune-mediated or congenital deficiency of the von Willebrand factor regulatory enzyme, a Disintegrin And Metalloproteinase with a Thrombospondin Type 1 motif, member 13 (ADAMTS13) which cause microthrombi to form and occlude the microvasculature. The occurrence of acute kidney injury (AKI) in TTP is rare and often underestimated due to confusion with hemolytic uremic syndrome (HUS). A 23-year-old Mestizo male patient presented with altered mental status, hemolytic anemia, thrombocytopenia, intermittent fever, laboratory tests suggestive of thrombotic microangiopathy, and clinical findings consistent with acute kidney injury. Predictive values of the platelet count, lactate dehydrogenase, absent active cancer, schistocytes, mean corpuscular volume, international normalized ratio, creatinine (PLASMIC) score, were used to assess the likelihood of ADAMTS13 deficiency, were employed, and enzymatic activity testing confirmed severe protein deficiency. Honduras' lack of advanced diagnostic capabilities is underscored, emphasizing the urgent need to invest in precision medical technology. ADAMTS13 testing allows for a more precise diagnosis of TTP, which is crucial for early diagnosis and timely treatment.

Thrombotic Microangiopathy in Pregnancy: Current Understanding and Management Strategies

Thrombotic microangiopathy (TMA) represents a heterogeneous group of disorders characterized by microvascular thrombosis and end-organ damage. Pregnancy-associated thrombotic microangiopathy (p-TMA) has emerged as a distinct clinical entity with unique diagnostic challenges. Identifying the specific form of p-TMA is critical for appropriate and timely management. This review offers a comprehensive overview of the various forms of thrombotic microangiopathies associated with pregnancy, highlighting our current understanding of their pathophysiology and the evolving landscape of diagnosis and treatment for each.

Folate Deficiency and Medication-Induced Severe Pancytopenia in a Bilateral Lung Transplantee

Folate is a water-soluble vitamin that is essential to DNA synthesis and replication. Its deficiency is a leading cause of megaloblastic anemia, which is often asymptomatic but can present with nonspecific symptoms, such as fatigue and lightheadedness. Folate deficiency can rarely present with pancytopenia, which has been described in past case reports but even more scarcely in transplant recipients. We present a 74-year-old bilateral lung transplantee who presented with presyncope and was found to have severe pancytopenia with folate deficiency during the initial workup. Some medications, including mycophenolate mofetil, valganciclovir, and posaconazole were held. Peripheral blood smear showed blastoid cells, but follow-up imaging and flow cytometry negated any concern for a malignant process. Bone marrow biopsy showed an extremely hypocellular marrow with marked trilineage hypoplasia. He required blood product transfusions, but his admission was overall uneventful with no life-threatening sequelae. His blood counts improved with folate replacement and discontinuation of offending medications. He was discharged after nine days in stable condition. Two months later, he experienced a milder and self-limited recurrence of pancytopenia with normal folate and cobalamin levels.

De-novo immune-mediated thrombotic thrombocytopenic purpura following surgical and non-surgical procedures: A systematic review

When de-novo immune-mediated thrombotic thrombocytopenic purpura (TTP) is diagnosed following an invasive procedure, clinical presentation patterns and outcomes are poorly defined. Therefore, in a systematic literature review of patients diagnosed with TTP following an invasive surgical or non-surgical procedure, we identified 19 studies reporting data on 25 patients. These data suggest that 1) TTP pathogenesis likely begins prior to the invasive procedure, 2) patients experience significant diagnostic delays, and 3) there is a high incidence of renal replacement therapy. Although invasive procedures may trigger TTP, further studies are needed to clarify the mechanisms underlying this association.

Interpretation: use of autoantibodies in children

Judicious use of autoantibodies in paediatrics can be challenging. Autoimmune conditions can present with a wide range of signs and symptoms, many of which are non-specific. In combination with clinical features and laboratory findings, autoantibodies can facilitate diagnosis and in certain cases inform prognosis. Evidence for use of autoantibodies to guide and monitor treatment is limited. Caution is necessary when interpreting adult studies. We summarise the use of autoantibodies in paediatric practice with a guide on how they may be used.

Recombinant ADAMTS13 in Congenital Thrombotic Thrombocytopenic Purpura

BACKGROUND

Congenital thrombotic thrombocytopenic purpura (TTP) results from severe hereditary deficiency of ADAMTS13. The efficacy and safety of recombinant ADAMTS13 and standard therapy (plasma-derived products) administered as routine prophylaxis or on-demand treatment in patients with congenital TTP is not known.

METHODS

In this phase 3, open-label, crossover trial, we randomly assigned patients in a 1:1 ratio to two 6-month periods of prophylaxis with recombinant ADAMTS13 (40 IU per kilogram of body weight, administered intravenously) or standard therapy, followed by the alternate treatment; thereafter, all the patients received recombinant ADAMTS13 for an additional 6 months. The trigger for this interim analysis was trial completion by at least 30 patients. The primary outcome was acute TTP events. Manifestations of TTP, safety, and pharmacokinetics were assessed. Patients who had an acute TTP event could receive on-demand treatment.

RESULTS

A total of 48 patients underwent randomization; 32 completed the trial. No acute TTP event occurred during prophylaxis with recombinant ADAMTS13, whereas 1 patient had an acute TTP event during prophylaxis with standard therapy (mean annualized event rate, 0.05). Thrombocytopenia was the most frequent TTP manifestation (annualized event rate, 0.74 with recombinant ADAMTS13 and 1.73 with standard therapy). Adverse events occurred in 71% of the patients with recombinant ADAMTS13 and in 84% with standard therapy. Adverse events that were considered by investigators to be related to the trial drug occurred in 9% of the patients with recombinant ADAMTS13 and in 48% with standard therapy. Trial-drug interruption or discontinuation due to adverse events occurred in no patients with recombinant ADAMTS13 and in 8 patients with standard therapy. No neutralizing antibodies developed during recombinant ADAMTS13 treatment. The mean maximum ADAMTS13 activity after recombinant ADAMTS13 treatment was 101%, as compared with 19% after standard therapy.

CONCLUSIONS

During prophylaxis with recombinant ADAMTS13 in patients with congenital TTP, ADAMTS13 activity reached approximately 100% of normal levels, adverse events were generally mild or moderate in severity, and TTP events and manifestations were rare. (Funded by Takeda Development Center Americas and Baxalta Innovations; ClinicalTrials.gov number, NCT03393975.).

Thrombotic Microangiopathy after a 15-year Treatment with Interferon Beta-1b in a Patient with Multiple Sclerosis: A Case Report and Review of Literature

A 54-year-old woman with multiple sclerosis treated with interferon-β (IFN-β)-1b for 15 years presented with sustained hypertension (240/124 mmHg) and retinal bleeding. She had proteinuria, anemia, thrombocytopenia, elevated serum creatinine levels, and haptoglobin depletion. Intravenous nicardipine stabilized her blood pressure, but her renal function and platelet count deteriorated. The initial disintegrin-like metalloprotease with thrombospondin type 1 motifs 13 (ADAMTS13) activity was 28% of normal without its inhibitor. The subsequent peripheral appearance of schistocytes suggested thrombotic microangiopathy (TMA). After IFN-β-1b cessation, the platelet count increased, and the blood pressure stabilized. The ADAMTS13 activity normalized, although the creatinine level did not. TMA may develop after the long-term use of IFN-β without adverse events.

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.

Uncommon Manifestation: Thrombotic Thrombocytopenic Purpura Presenting Solely as Petechial Rash

Thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening disorder typically presenting with a classic pentad of symptoms: thrombocytopenia, microangiopathic hemolytic anemia, neurological abnormalities, renal dysfunction, and fever. This report explores an unusual presentation of TTP in a 47-year-old female with a medical history of hypertension, hyperlipidemia, and chronic TTP, who exhibited only petechial rashes, generalized weakness, and headache. Notably, the petechial rash, a less common manifestation of TTP, became a pivotal clue for the diagnosis, underscoring the necessity for vigilance even when classic symptoms are absent. This case reinforces the imperative of a high suspicion index for TTP, especially in patients with thrombocytopenia and hemolytic anemia, irrespective of other traditional signs. Plasmapheresis remains the treatment cornerstone, removing autoantibodies and replenishing ADAMTS13, as evidenced by the patient's initial response. The administration of rituximab, targeting B cells to mitigate autoantibody production against ADAMTS13, featured prominently in her management, aligning with its recognized role in refractory or relapsing TTP cases. Despite an encouraging response to rituximab, a subsequent decline in platelet count indicated the unpredictable nature of TTP and the necessity for multi-pronged therapeutic strategies. The patient's medical background and persistently low ADAMTS13 levels hinted at a chronic relapsing trajectory associated with increased morbidity and mortality. This necessitates ongoing vigilance and treatment flexibility. Highlighting this atypical TTP presentation, the report calls for immediate, robust intervention, serving as a critical reminder of the heterogeneity of TTP manifestations and the complexities in its management, thereby contributing to broader clinical awareness and improved patient prognoses.

Apadamtase Alfa: First Approval

Apadamtase alfa (ADAMTS13, recombinant-krhn; ADZYNMA), a human recombinant form of a disintegrin and metalloproteinase with thrombospondin motifs 13 (ADAMTS13), is being developed by Takeda under license from KM biologics for thrombotic thrombocytopenic purpura (TTP) and sickle cell disease. On 9 November 2023, apadamtase alfa was approved in the USA for prophylactic and on-demand enzyme replacement therapy (ERT) in paediatric and adult patients with congenital TTP. Apadamtase alfa is under regulatory review for congenital TTP in the EU and Japan, and is under clinical development for immune-mediated TTP in several countries worldwide. Clinical development of apadamtase alfa for vaso-occlusive crisis related to sickle cell anaemia is underway in the USA. This article summarizes the milestones in the development of apadamtase alfa leading to this first approval in the USA for congenital TTP.

Repurposing of rituximab biosimilars to treat B cell mediated autoimmune diseases

Rituximab, the first monoclonal antibody approved for the treatment of lymphoma, eventually became one of the most popular and versatile drugs ever in terms of clinical application and revenue. Since its patent expiration, and consequently, the loss of exclusivity of the original biologic, its repurposing as an off-label drug has increased dramatically, propelled by the development and commercialization of its many biosimilars. Currently, rituximab is prescribed worldwide to treat a vast range of autoimmune diseases mediated by B cells. Here, we present a comprehensive overview of rituximab repurposing in 115 autoimmune diseases across 17 medical specialties, sourced from over 1530 publications. Our work highlights the extent of its off-label use and clinical benefits, underlining the success of rituximab repurposing for both common and orphan immune-related diseases. We discuss the scientific mechanism associated with its clinical efficacy and provide additional indications for which rituximab could be investigated. Our study presents rituximab as a flagship example of drug repurposing owing to its central role in targeting cluster of differentiate 20 positive (CD20) B cells in 115 autoimmune diseases.

Pathological Mechanisms and Novel Testing Methods in Thrombotic Thrombocytopenic Purpura

Thrombotic thrombocytopenic purpura (TTP) is an uncommon, but potentially disabling or even deadly, thrombotic microangiopathy with a well-studied mechanism of ADAMTS13 deficiency or dysfunction. While established treatments are largely effective, the standard ADAMTS13 testing required to definitively diagnose TTP may cause delays in diagnosis and treatment, highlighting the need for rapid and effective diagnostic methods. Additionally, the heterogeneous presentation and varied inciting events of TTP suggest more variation in its mechanism than previously thought, implying three potential pathways rather than the accepted two. The recent discovery of ADAMTS13 conformation as a potential contributor to TTP in addition to the proposal of using the absolute immature platelet count (A-IPC) as a biomarker, present novel areas for monitoring and treatment. A-IPC in particular may serve as a more rapid and accurate diagnostic test to distinguish TTP from non-TTP TMAs and to monitor treatment response and relapse. These considerations highlight the need to further study TTP in order to improve best practices and patient care.

COVID-Induced Thrombotic Thrombocytopenic Purpura: A Case Report and Treatment-Focused Review

Thrombotic thrombocytopenic purpura (TTP) is a rare disease that is part of a vast spectrum of thrombotic microangiopathies (TMAs). Despite the rarity of TTP, clinicians must maintain a high suspicion of this disease. The condition is characterized by fever, low platelets, hemolytic anemia, renal abnormalities, and neurological dysfunction. However, all these symptoms are not necessarily present in all the patients. In this review, we describe a case of a 51-year-old female who presented to the emergency department (ED) with chief complaints of dizziness and lightheadedness, subsequently leading to a diagnosis of TTP, caused as a result of COVID-19. This review raises awareness so that there is early recognition of any hematological manifestations associated with COVID-19, reducing the morbidity and mortality associated with the disease. Due to the unpredictability of COVID-19 and its complications, robust research is needed to understand the mechanism and determine which patients are more at risk for adverse outcomes.

Stress-induced hyperglycemia is associated with the mortality of thrombotic thrombocytopenic purpura patients

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) is a rare thrombotic microangiopathy with a rapid progression and high mortality rate. We aimed to explore early risk factors for mortality in patients with TTP.

METHODS

We conducted a retrospective analysis of 42 TTP patients that were admitted to our hospital between 2000 and 2021, with a median age of 49 (29-63) years. Risk factors for mortality were evaluated using multivariate logistic regression. Receiver operating characteristic curve analysis was used to determine the cut-off value of glucose for predicting mortality in patients, which was validated by comparison to a similar cohort in the published literature.

RESULTS

Elevated glucose level and reduced red blood cells (RBC) counts were risk factors for mortality in patients with TTP (glucose, odds ratio and 95% confidence interval: 2.476 [1.368-4.484]; RBC, odds ratio and 95% confidence interval: 0.095 [0.011-0.799]). The area under the curve of glucose was 0.827, and the cut-off value was 9.2 mmol/L, with a sensitivity of 75.0% and specificity of 95.8%. A total of 26 cases from the validation cohort had a sensitivity of 71.0% and a specificity of 84.0%. The change trends of the TTP-related laboratory indices differed during hospitalization.

CONCLUSION

Hyperglycemia at admission and unstable blood glucose levels during hospitalization may be potential predictors of mortality for TTP patients. The improved prognosis was associated with the recovery of platelet counts and a significant decrease in serum lactate dehydrogenase after five days of treatment.

HELLP Syndrome and Differential Diagnosis with Other Thrombotic Microangiopathies in Pregnancy

Thrombotic microangiopathies (TMAs) comprise a distinct group of diseases with different manifestations that can occur in both pediatric and adult patients. They can be hereditary or acquired, with subtle onset or a rapidly progressive course, and they are particularly known for their morbidity and mortality. Pregnancy is a high-risk time for the development of several types of thrombotic microangiopathies. The three major syndromes are hemolysis, elevated liver function tests, and low platelets (HELLP); hemolytic uremic syndrome (HUS); and thrombotic thrombocytopenic purpura (TTP). Because of their rarity, clinical information and therapeutic results related to these conditions are often obtained from case reports, small series, registries, and reviews. The collection of individual observations, the evolution of diagnostic laboratories that have identified autoimmune and/or genetic abnormalities using von Willebrand factor post-secretion processing or genetic-functional alterations in the regulation of alternative complement pathways in some of these TMAs, and, most importantly, the introduction of advanced treatments, have enabled the preservation of affected organs and improved survival rates. Although TMAs may show different etiopathogenesis routes, they all show the presence of pathological lesions, which are characterized by endothelial damage and the formation of thrombi rich in platelets at the microvascular level, as a common denominator, and thrombotic damage to microcirculation pathways induces "mechanical" (microangiopathic) hemolytic anemia, the consumption of platelets, and ischemic organ damage. In this review, we highlight the current knowledge about the diagnosis and management of these complications during pregnancy.

Case report: Thrombotic thrombocytopenic purpura in a pregnant woman with lupus membranous nephropathy: a diagnostic challenge

A 27-year-old female at 20th week of pregnancy was admitted with edema, foamy urine, but normal blood pressure. Her blood count was normal, she had proteinuria of 3 g/day, creatinine 0.4 mg/dl, albumin 2.4 g/dl, and cholesterol 355 mg/dl. Antinuclear antibodies 1/160, but Anti-DNA, anticardiolipin antibodies and lupus anticoagulant were negative, with normal serum C3 and C4. A renal biopsy showed secondary membranous glomerulopathy, most likely lupus class V pure. Steroids, azathioprine, and aspirin were initiated, up to 28 weeks of pregnancy, when she developed severe hypertension, photopsia, headache, anasarca, extensive bruising of the extremities, severe anemia, thrombocytopenia, and creatinine rose to 2.09 mg/dl with preserved diuresis. A female infant, 1045 grams, was delivered by emergency caesarean section. Following the surgery, she experienced diplopia, dysarthria, bradypsychia, and sensory alterations in the lower extremities, necessitating emergency hemodialysis due to pulmonary congestion. Blood smear revealed schistocytes, LDH elevated at 1148 IU/L, while transaminases and liver function remained normal, suggesting thrombotic thrombocytopenic purpura. ADAMTS13 revealed 6% activity with the presence of inhibitor. Mycophenolate and daily plasmapheresis with fresh frozen plasma replacement yielded unsatisfactory response, unaffected by the addition of methylprednisolone pulses and rituximab. Eventually, intravenous cyclophosphamide was introduced, resulting in complete hematological remission and normalization of ADAMTS13, however dialysis-dependence persisted and four years later, right renal cancer prompted bilateral nephrectomy. After a total follow-up of six years, she remained free of neoplastic recurrence and lupus activity, receiving prednisone and hydroxychloroquine. The differential diagnosis of microangiopathic syndrome in a pregnant lupus patient is discussed.

Altered Mental Status in the Setting of Thrombotic Thrombocytopenic Purpura (TTP) and Spontaneous Coronary Artery Dissection (SCAD): A Case Report and Literature Review

Altered mental status (AMS) is a common condition encountered in daily practice. Finding the cause is essential for treatment, but sometimes this may be challenging. Spontaneous coronary artery dissection (SCAD) is frequently underdiagnosed and is a potentially fatal cause of acute coronary syndrome. Clinical presentation depends on the extent of SCAD, ranging from unstable angina to sudden death. AMS has not been reported with this condition, but it may be possible in hypoperfusion states. Thrombotic thrombocytopenic purpura (TTP) is part of the microangiopathic hemolytic anemia (MAHA) spectrum, presenting with AMS as the cardinal symptom. TTP is a clinical emergency, and a high index of suspicion should be present as the mortality rate in untreated patients is extremely high and can be significantly reduced with proper treatment. We present a case of a 44-year-old female with a past medical history of antiphospholipid syndrome not on anticoagulation, peptic ulcer disease, chronic kidney disease, stroke, seizures, congestive heart failure with reduced ejection fraction (EF 40%), two non-ST-segment elevation myocardial infarctions not on dual antiplatelet therapy due to a history of gastrointestinal bleeding, and TTP, admitted to the hospital with AMS. The patient was diagnosed with two life-threatening pathologies with overlapping features but opposing management; TTP may have been caused by SCAD, even though this has never been reported. It is essential to recognize that while a single diagnosis frequently explains a patient's clinical manifestations, there are instances when various conditions may be present.

Recent advances in the management of immune thrombocytopenic purpura (ITP): A comprehensive review

Autoimmune disorders place a substantial burden on the healthcare system all over the world affecting almost 3% to 8% of the population. Immune thrombocytopenic purpura (ITP), also known as idiopathic thrombocytopenic purpura, is a blood disorder in which the body immune system destroys platelets, leading to low platelet counts in the blood (peripheral blood platelet count < 150 × 109/L). Although the pathophysiology of ITP is not fully understood, it is believed to result from a complex interplay between hereditary and environmental variables. Certain factors, such as a low platelet count, history of bleeding, and certain comorbidities can increase the risk of severe bleeding in patients with ITP. Corticosteroids, intravenous immunoglobulin (IVIG), immunosuppressants, rituximab, and thrombopoietin receptor agonists (TPO-RAs) are some of the advanced treatments for ITP. Although these therapies may be successful, they also carry the risk of negative effects. Recently, significant advancements have been made in the understanding and treatment of ITP. There is still much to learn about the disease, and new, more effective treatments are needed. This comprehensive review offers a comprehensive assessment of recent advancements in ITP management, with a focus on active research projects, novel therapeutic targets, new treatment modalities, and areas of uncertainty and unmet needs. According to research, it is crucial to develop individualized treatment plans for ITP patients based on their age, platelet count, risk of bleeding, and comorbidities. The article also looks at how future developments in gene editing, bispecific antibody therapies, and cellular therapy may completely change the treatment of ITP.

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.

Thrombotic thrombocytopenic purpura that developed 3 years after systemic lupus erythematosus had remitted with rituximab therapy

Patients with systemic lupus erythematosus (SLE) occasionally develop thrombotic thrombocytopenic purpura (TTP), which can be fatal. Here, we report a case of TTP developing 3 years after SLE remitted with rituximab (RTX) therapy. A 50-year-old woman was treated with RTX for marked immune thrombocytopenic purpura and autoimmune haemolytic anaemia due to SLE relapse. After induction of remission, she was treated with prednisolone alone without maintenance therapy with RTX. Approximately 3 years later, she was readmitted with marked thrombocytopenia and severe renal dysfunction. On admission, she was diagnosed with TTP for the first time based on severe reduction in a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) activity and detection of ADAMTS13 inhibitors. CD19+ B cells in the patient's serum increased to 34%, suggesting that B cells had reactivated once the effect of RTX had subsided. The patient was successfully treated with plasmapheresis, glucocorticoid pulse therapy, and RTX. There are no previous reports of newly diagnosed TTP with ADAMTS13 inhibitor production after having achieved remission of SLE with RTX. Therefore, our report also discusses the potential mechanisms of production of new autoantibodies after B-cell depletion therapy.

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.

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.

Acquired thrombotic thrombocytopenic purpura as a clinical manifestation of pulmonary tuberculosis: a case report

Introduction

Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy associated with severe ADAMTS13 deficiency that can be potentially fatal if not treated in a timely manner.

Case report

A 49-year-old previously healthy woman was admitted with a 3-month history of thoracoabdominal pain and headache associated with loss of appetite, emesis, nocturnal diaphoresis, and unintentional loss of 10 kg. On admission she presented anemia, thrombocytopenia, schistocytes in peripheral blood smear, and ADAMTS13 in 1.4%. Due to laboratory findings a diagnosis of TTP was established, and plasma exchange therapy and steroid pulses were started, with resolution of hematological alterations. Within the studies to determine etiology of TTP, pulmonary tuberculosis (TB) was found, neoplastic and autoimmune pathologies were excluded. The tetraconjugated treatment was initiated with optimal tolerance.

Conclusions

Upon clinical suspicion of TTP, plasma exchange therapy should be initiated urgently; infectious, neoplastic, or autoimmune pathologies can be triggers; in this case, pulmonary TB was confirmed.

Treatment Challenges of Acquired Thrombotic Thrombocytopenic Purpura in Pediatric Patients From a Low-Income Country

This study presents a comprehensive analysis of two cases of acquired thrombotic thrombocytopenic purpura (aTTP) observed in pediatric patients from a low-income country. In the instances described, both patients underwent a treatment regimen involving plasma exchange and immunosuppressive therapy conducted without the use of caplacizumab. Caplacizumab, an approved drug for adults known for its limited availability and high cost, has exhibited efficacy in reducing response time and recurrence frequency in aTTP cases. This approach resulted in significant clinical improvement and eventual remission of symptoms in one of the cases. These cases underscore the urgent necessity for a more inclusive approach in national health programs and international treatment guidelines. Specifically, there is a call to expand the existing comprehensive treatment algorithms to accommodate countries lacking access to caplacizumab. This adaptation aims to ensure the availability of suitable and effective treatment options for aTTP patients in regions facing limited pharmaceutical accessibility.

Case report: A case of sepsis caused by rickettsial infection-induced hemophagocytic syndrome

Hemophagocytic lymphohistiocytosis (HLH) is a rare histiocytic disorder characterized by reactive hyperplasia of the mononuclear phagocytic system, which is primarily caused by dysfunction of cytotoxic killer cells and natural killer cells, leading to antigen clearance barriers and the overactivation of the mononuclear phagocytic system due to continuous antigen stimulation. HLH encompasses a group of clinical syndromes marked by the overproduction of inflammatory cytokines. A 68-year-old Chinese man presented with persistent fever, chills, nausea, and vomiting; the patient had no history of any underlying conditions. Laboratory investigations revealed decreased levels of red blood cells, white blood cells, and platelets, along with reduced natural killer cell activity, increased CD25, hyperferritinemia, and the detection of Rickettsia DNA in his blood, meeting the diagnostic criteria of the Histiocyte Society HLH-2004 guidelines. The patient was treated with antibiotics, improving anemia, glucocorticoid therapy, and continuous renal replacement therapy (CRRT), temporarily improving his condition. However, the patient died after 2 years from chronic renal failure caused by septic shock.

Use of n-acetylcysteine therapy in patients with relapsed refractory thrombotic thrombocytopenic purpura

There is limited data on the use of NAC in the literature. We would like to present the satisfactory results we obtained in our resistant and relapsed patients as a case series.Thrombotic thrombocytopenic purpura (TTP) is a life-threatening thrombotic microangiopathy caused by ADAMTS13 (a disintegrin with thrombospondin type 1 motif and metalloprotease activity, member13) deficiency. Von Willebrand factor (vWF) initiates platelet aggregation and thus thrombus formation. The multimers of vWF are cleaved by ADAMTS13. Because of the decreased activity of ADAMTS13, ultra-large multimers accumulate and end-organ damage occurs. TTP is characterized by microangiopathic hemolytic anemia (MAHA), severe thrombocytopenia, and organ ischemia resulting from vascular occlusion caused by thrombi. Plasma exchange therapy (PEX) remains the mainstay of TTP therapy. Patients who do not respond to PEX and corticosteroids require additional treatments such as rituximab and caplacizumab. NAC reduces disulfide bonds in mucin polymers through its free sulfhydryl group. Thus, the size and viscosity of the mucins are reduced. VWF is structurally similar to mucin. Based on this similarity, Chen and colleagues showed that NAC can reduce the size and reactivity of ultralarge multimers of vWF, such as ADAMTS13. Currently, there is not much information to suggest that NAC has any clinical value in the treatment of TTP. In this case series of 4 refractory patients, we would like to present the responses we obtained with the addition of NAC therapy. NAC can be added to PEX and glucocorticoid therapy as supportive therapy, especially in unresponsive patients.

Thromboembolism after Astra Zeneca COVID-19 vaccine: Not always PF4- antibody mediated

Cases of thromboembolic events in 2021 flared up the discussion about the safety of Astra Zeneca's AZD1222 vaccine. We hereby report three cases of pulmonary embolism (PE), one case of extended portal vein thrombosis, and one case of combined portal vein thrombosis and PE within 2 weeks after vaccination with the Astra Zeneca AZD1222 vaccine in a 60-year-old, a 50-year old, a 33-year-old, a 30-year old, and a 40-year-old male in that year. All patients were healthy before. In three patients, we observed thrombocytopenia and to some extent unusually low antibody levels for the Spike Protein (S-protein), while the other two had normal thrombocyte counts. Only one patient had anti-platelet factor 4 (PF4)-antibodies detectable as it has been described in the "heparin-induced thrombocytopenia (HIT)-like" disease of "vaccine-induced prothrombotic immune thrombocytopenia" (VIPIT) and we therefore assume that heterogeneous mechanisms led to PE. Therefore, we advise to collect and report more cases, in order to determine the age-related risks of vaccination balanced against the benefits of immunity to SARS-COV-2 for the AZD1222 vaccine in order to gain knowledge for the next pandemic.

Effectiveness and safety of caplacizumab in acquired thrombotic thrombocytopenic purpura: health technology assessment and classification according to the methodology established in Colombia

OBJECTIVES

Acquired thrombotic thrombocytopenic purpura (aTTP) is a rare hematological disease whose clinical management includes caplacizumab along with plasma exchange and immunosuppression, according to international guidelines. Caplacizumab has been available in Colombia since 2022. This study seeks to determine the therapeutic classification of caplacizumab according to the methodology of the Instituto de Evaluación Tecnológica en Salud.

METHODS

The classification was carried out through a deliberative process following the modified Delphi technique, with a panel of experts, made up of four hemato-oncologists, a pharmaceutical chemist, and a patient. The results of effectiveness and safety obtained through a systematic review, therapeutic thresholds (clinical significance), and degree of acceptability (willingness to use the technology) were used for the classification.

RESULTS

Fourteen effectiveness and safety outcomes were submitted for the classification process. Caplacizumab showed clinical significance for some effectiveness outcomes, was not considered inferior in terms of safety, and displayed acceptability of use. Through consensus, the panel determined that caplacizumab plus the standard regimen is superior to the standard regimen in terms of treatment response and composite outcome, and no different for the other effectiveness and safety outcomes. Likewise, in overall terms, the panel determined that caplacizumab together with the standard regimen is superior to the standard regimen.

CONCLUSION

Treatment with caplacizumab together with the standard regimen was considered superior to the standard regimen for the treatment of patients with aTTP, as it showed clinically significant benefits in critical outcomes for decision making, and a safety profile no different to its comparator.

Clinical Features and Risk Factors of Relapse and Mortality in Thrombotic Thrombocytopenic Purpura Patients: A Seven-Year Experience

Background: Thrombotic thrombocytopenic purpura (TTP) is associated with microangiopathic hemolytic anemia, thrombocytopenia, and microvascular thrombosis. No comprehensive report exists on clinical characteristics and risk factors of relapse and mortality in Iranian TTP patients. In this study, we aimed to report clinical features of Iranian TTP patients, to evaluate disease relapse and mortality rate and their associated risk factors. Materials and Methods: This study was a cohort study of patients diagnosed with microangiopathic hemolytic anemia admitted to the Shariati Hospital, Tehran, a referral center for TTP patients, from 2010 to 2017. Demographic, clinical, and laboratory data were recorded and patients were followed for 3 years regarding disease relapse and mortality. Results:  114 patients (80 females, 34 males) with a mean age of 39.3 ± 14.99 years were included.  Hematologic and neurologic symptoms were the most common manifestations. Abnormal laboratory findings at the presentation included thrombocytopenia, anemia, and elevated LDH. All patients were treated with plasma exchange, and 75.5% of them had a response to treatment, while the 3-year relapse and mortality rate was 23.6 and 26.3%.  Lower platelet count was a predictor of disease relapse. Age, hematological, or neurological initial presentation were associated with TTP mortality. Conclusion: Based on the largest study of TTP patients ever in Iran, the demographic and clinical characteristics of Iranian TTP patients are similar to other existing reports. Knowledge of the risk factors for TTP relapse and mortality could be useful to alert hematologists for prompt therapeutic actions when necessary.