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.

Managing surgical relapse risk in acquired thrombotic thrombocytopenic purpura: a systematic review.

•Thrombotic thrombocytopenic purpura (TTP) may relapse after surgery.•In a systematic review, we assessed preoperative TTP prophylaxis.•Pre-emptive ADAMTS-13 activity measurement prior to surgery may improve relapse risk.•Preoperative TTP prophylaxis may lower surgical relapse risk.

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

DISCLAIMER: In an effort to expedite the publication of articles, AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time. 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.

Vascular endothelial-cadherin is involved in endothelial cell detachment during thrombotic thrombocytopenic purpura.

BACKGROUND: Immune thrombotic thrombocytopenic purpura (i-TTP) is a life-threatening thrombotic microangiopathy linked to ADAMTS-13 deficiency. It has long been assumed that the activation of endothelial cells is the triggering factor for the thrombotic thrombocytopenic purpura crisis. Circulating endothelial cells (CECs) have been shown to be a biomarker of vascular damage and are associated with the clinical severity of i-TTP. However, the mechanisms leading to endothelial cell detachment remain unclear. OBJECTIVES: We investigated junctional destabilization the mechanisms underlying cell detachment in thrombotic thrombocytopenic purpura. METHODS: We quantified CECs in i-TTP patients and investigated the effect of plasmas in vitro by measuring phosphorylation and internalization of vascular endothelial (VE)-Cadherin and in vivo in a vascular permeability model. RESULTS: In plasma from i-TTP patients, we show that CEC count is associated with severity and correlated to intracellular calcium influx (P < .01). In vitro, serum from i-TTP patients induced stronger detachment of human umbilical vein endothelial cells than serum from control patients (P < .001). Plasma from i-TTP patients induced a higher calcium-dependent phosphorylation (P < .05) and internalization (P < .05) of VE-cadherin compared with plasma from control patients. This effect could be reproduced by immunoglobulin (Ig)G fraction isolated from patient plasma and, in particular, by the F(ab)'2 fragments of the corresponding IgG. In addition, subcutaneous injection of i-TTP plasma into mice resulted in higher vascular permeability than plasma from control patients. An inhibitor of endothelial calcium influx, ITF1697, normalized this increase in permeability. CONCLUSION: Our results suggest that plasma-induced endothelial activation also leads to an increase in vascular permeability. They contribute to the understanding of the mechanisms behind the presence of elevated CECs in patients' blood by linking endothelial activation to endothelial injury.

Navigating the Nexus: Lenalidomide-Associated Thrombotic Thrombocytopenic Purpura.

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening thrombotic microangiopathy (TMA) marked by thrombocytopenia, microangiopathic hemolytic anemia, and microvascular thrombosis leading to end-organ damage. While TTP commonly results from hereditary or acquired ADAMTS13 deficiency, its association with lenalidomide is notably rare. The link between lenalidomide and TMA is unclear and requires more studies, given the high mortality risk associated with TTP. The underlying mechanism may involve immunomodulatory effects leading to ADAMTS13 inhibitory antibody formation. Herein, we present a case of a 56-year-old male with a history of multiple myeloma status post autologous stem cell transplant, on lenalidomide maintenance therapy for over five years, who presented with progressive weakness, jaundice, palpitations, and paraesthesia in his extremities. On arrival, the patient was afebrile and was neurologically intact except for the subjective paraesthesia. He was found to have critically low ADAMTS13 activity at <0.03 IU/mL and detectable ADAMTS13 inhibitors, with other findings of TTP, requiring discontinuation of lenalidomide, in addition to receiving treatment for this life-threatening TMA.

Practical approach to thrombocytopenia in patients with sepsis: a narrative review.

Thrombocytopenia frequently occurs in patients with sepsis. Disseminated intravascular coagulation (DIC) may be a possible cause of thrombocytopenia owing to its high prevalence and association with poor outcomes; however, it is important to keep the presence of other diseases in mind in sepsis practice. Thrombotic microangiopathy (TMA), which is characterized by thrombotic thrombocytopenic purpura, Shiga toxin-producing Escherichia coli hemolytic uremic syndrome (HUS), and complement-mediated HUS, is characterized by thrombocytopenia, microangiopathic hemolytic anemia, and organ damage. TMA has become widely recognized in recent years because of the development of specific treatments. Previous studies have reported a remarkably lower prevalence of TMA than DIC; however, its epidemiology is not well defined, and there may be cases in which TMA is not correctly diagnosed, resulting in poor outcomes. Therefore, it is important to differentiate DIC from TMA. Nevertheless, differentiating between DIC and TMA remains a challenge as indicated by previous reports that most patients with TMA can be diagnosed as DIC using the universal coagulation scoring system. Several algorithms to differentiate sepsis-related DIC from TMA have been suggested, contributing to improving the care of septic patients with thrombocytopenia; however, it may be difficult to apply these algorithms to patients with coexisting DIC and TMA, which has recently been reported. This review describes the disease characteristics, including epidemiology, pathophysiology, and treatment, of DIC, TMA, and other diseases with thrombocytopenia and proposes a novel practical approach flow, which is characterized by the initiation of the diagnosis of TMA in parallel with the diagnosis of DIC. This practical flow also refers to the longitudinal diagnosis and treatment flow with TMA in mind and real clinical timeframes. In conclusion, we aim to widely disseminate the results of this review that emphasize the importance of incorporating consideration of TMA in the management of septic DIC. We anticipate that this practical new approach for the diagnostic and treatment flow will lead to the appropriate diagnosis and treatment of complex cases, improve patient outcomes, and generate new epidemiological evidence regarding TMA.

Role of plasma exchange in a post-partum case of severe thrombotic thrombocytopenic purpura with acute kidney injury.

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening disease present with the classic pentad of microangiopathic hemolytic anemia (MAHA), fever, neurologic changes, thrombocytopenia, and renal dysfunction. In a diagnostic dilemma, therapeutic plasma exchange (TPE) is a choice of life-saving intervention. In this, we assess the efficacy of TPE in a suspected case of post-partum TTP. A 27 years old female was admitted in an emergency on day 8 after a lower segment cesarian section (LSCS) with unresponsive behavior for 3 days and with TTP. She was normal 32 days back with her second, 7-month pregnancy. Ultrasonography (USG) showed an umbilical cord around the neck of the baby. On the fifth post-operative day, she was shifted to emergency with fever, generalized anasarca, gastrointestinal tract (GI) bleeding, low platelet count, and low Hb, with a poor Glasgow coma scale (GCS) of 6. On the bases of serum urea and serum creatinine, she presented acute kidney injury with encephalopathy. At emergency, she was unresponsive to mechanical ventilation and supportive treatment; hence, therapeutic plasma exchange was performed. After eight TPE cycles, the patient presented with an improved hematological and renal profile with good GCS. TPE is helpful and life-saving for suspected TTP patients with AKI.

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.

Acquired Thrombotic Thrombocytopenic Purpura (TTP) Presenting With Synthetic Cannabinoid Use.

Synthetic cannabinoids (SCs) have become commercially available throughout the United States as manufacturers circumvent regulations with labels stating "not for human consumption" with misleading advertisements, resulting in the consumption of products that are not safe or regulated. We present a case report of a middle-aged woman exhibiting altered mental status secondary to SC use who was found to have severe thrombocytopenia and hemolytic anemia. She was later confirmed to have thrombotic thrombocytopenic purpura (TTP) through ADAMTS13 testing. TTP is one of several platelet-related disorders presenting with findings of hemolytic anemia and thrombocytopenia. The presence of altered mental status is typically used as a symptomatic differentiator between hemolytic uremic syndrome, immune thrombocytopenic purpura, and TTP. SCs can cause superimposed altered mental status, which, in the setting of a concomitant platelet disorder, can complicate the standard workup and prolong the time to a final diagnosis. This case serves as an essential reminder that collecting detailed social history and promptly recognizing laboratory abnormalities is critical for early recognition of TTP, as the diagnosis is time-sensitive and delays in recognition can lead to significant morbidity and mortality.

The history of thrombotic thrombocytopenic purpura research: a narrative review.

Background and Objective: Thrombotic thrombocytopenic purpura (TTP) is a rare but debilitating thrombotic microangiopathy that results from severe deficiency of the enzyme ADAMTS13. The disorder was first described in the early 20th century, but the pathophysiology of the disease has only been elucidated in the past three decades. In this narrative review, we will summarize the milestone moments in the history of TTP research and discovery. Methods: We searched literature using PubMed from 1924 to 2023 using the following free text searches: "thrombotic thrombocytopenic purpura", "Moschcowitz disease", and "thrombotic microangiopathy". We found 6,917 peer-reviewed articles and sorted through these for relevant literature pertinent to the review. A total of 46 articles were included for review and the remainder were excluded. Key Content and Findings: The history of TTP research was reviewed, with a sampling of major events in the evolution of the understanding of the pathophysiology and treatment of the disease discussed here. There remains much to be learned about the nature of the disease in order to develop more specific and less harmful treatments. Conclusions: An overview of the major discoveries that have led to our current understanding of TTP reveals the results of collaboration of multiple groups of physicians and scientists through the past century, with additional breakthroughs likely to occur in the future because of that same collaborative spirit.

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

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

A Complicated Case of Thrombotic Thrombocytopenic Purpura in Pregnancy with Superimposed Preeclampsia.

A 32-year-old woman at 26 weeks gestation presented with severe unexplained thrombocytopenia with signs and symptoms of severe pregnancy-induced hypertension and what appeared to be hemolysis, elevated liver enzymes, and low platelet count syndrome, leading to a severe diagnostic challenge. The multidisciplinary team identified her condition as thrombotic thrombocytopenic purpura. Timely management decisions and multidisciplinary care ensured a safe delivery.

Anti-factor H Autoantibody-Associated Hemolytic Uremic Syndrome: A Rare Entity in a Pediatric Patient.

An 11-year-old patient presented with the primary complaint of hematuria and vomiting. On further investigation and a series of diagnostic tests, including a biopsy and thrombotic microangiopathy (TMA) profile, the patient was diagnosed with thrombotic microangiopathy. TMA is a pathological process involving endothelial cell injury, leading to thrombocytopenia and microangiopathic hemolytic anemia. This case highlights the importance of considering TMA in pediatric patients presenting with nonspecific symptoms, such as loss of appetite. Further research is needed to understand the pathophysiology and optimal management strategies for pediatric TMA. This case adds to the growing body of literature on pediatric TMA and underscores the need for a high index of suspicion in similar clinical scenarios.

Renal Involvement in Thrombotic Thrombocytopenic Purpura: Is It Time to Challenge the Old Paradigm?

Thrombotic thrombocytopenic purpura (TTP) is clinical-pathological entity characterized by microangiopathic hemolytic anemia associated with end-organ dysfunction. Traditionally, TTP was characterized by the classic pentad of fever, thrombocytopenia, hemolytic anemia, renal impairment, and neurological manifestations. However, this classic pentad is only observed in 40% of cases. We herein describe the case of a female patient who presented with epigastric pain and vomiting and found to have TTP without the classic pentad but with rapidly progressive renal dysfunction.

Plasma exchange in thrombotic thrombocytopenic purpuras.

INTRODUCTION: Thrombotic thrombocytopenic purpura (TTP) is a rare but potentially fatal hematological disorder that requires urgent treatment. Once the diagnosis has been made, plasma exchange (PE) must be started immediately and until a response is obtained. AIM: Evaluate PE in terms of responses and complications in the treatment of TTP. METHODS: This was a monocentric, descriptive, retrospective study including patients in whom TTP was diagnosed and treated with plasmapheresis in the clinical hematology department at Aziza Othmana Hospital, between January 2010 and December 2020. RESULTS: Our study included 26 patients. PE was initiated within a median of 1 day. The rhythm of exchanges was daily in 22 patients. Twenty PE-related complications were noted, hypocalcemia being the most frequent (30%). CR was achieved in 15 patients after PE alone. Nine patients were refractory, and six received 2nd-line treatment, with CR achieved in five patients. Relapse was noted in six patients (40%). They were treated by PE and only one patient received rituximab. Four patients had a response. The overall response rate was 69% and overall mortality was 30%. OS at 2 years was 68,3% and RFS was 84,4%. Factors associated with the achievement of CR were the fall in LDH at D5 of treatment (p=0,027,OR=0,59 ;IC 95%[0,32-1,08]) and the daily rhythm of PE (p=0,005, OR=0,35; IC 95%[0,14-0,91]). CONCLUSION: Our results were comparable to those of the literature, but the rate of refractory disease was higher. Rituximab may enhance our results.

Thrombotic microangiopathy following a white-lipped pit viper envenomation.

Certain snake envenomation patients with consumptive coagulopathy, termed venom-induced consumption coagulopathy, develop thrombotic microangiopathy (TMA). Due to predominant renal involvement, TMA is said to resemble haemolytic uraemic syndrome and is treated with haemodialysis. We present a case of a young male who presented to the emergency department after being bitten by a white-lipped pit viper (Trimeresurus albolabris). He developed heart failure in addition to acute kidney injury secondary to TMA. He was treated with 30 vials of anti-snake venom according to national guidelines and underwent haemodialysis. Despite haemodialysis, the patient's ventilatory parameters continued to worsen, necessitating invasive mechanical ventilation. Thus, he was initiated on plasma exchange therapy, to which the patient responded well. TMA has not been reported in Trimeresurus envenomations yet, to the best of our knowledge. Additionally, plasma exchange therapy can be considered an adjunctive therapy for snakebite patients who develop TMA.

A Rare Case of Atypical Hemolytic Uremic Syndrome (aHUS) Precipitated by Dengue and the Treatment Landscape in Singapore.

Atypical hemolytic uremic syndrome (aHUS) is a rare disease caused by uncontrolled complement activation due to complement dysregulation. It is often triggered by precipitating events such as infections, inflammation, pregnancy, or medications. Dengue, an endemic viral infection in Southeast Asia, can activate the complement pathway, thereby triggering aHUS in genetically susceptible individuals. Here, we present the case of a 33-year-old male who presented with Dengue fever and subsequently developed aHUS. Plasma exchange (PLEX) successfully normalized his neurological status and hematological parameters. Although his renal function improved, it failed to normalize. Eculizumab, a monoclonal antibody that inhibits C5, was administered for a total of six months. The treatment was successfully discontinued without evidence of relapse after six months of follow-up. This case report demonstrates the safety of discontinuing eculizumab in patients who do not possess pathogenic mutations or variants in complement factors.

How We Interpret Thrombosis with Thrombocytopenia Syndrome?

Platelets play an important role in hemostasis, and a low platelet count usually increases the risk of bleeding. Conditions in which thrombosis occurs despite low platelet counts are referred to as thrombosis with thrombocytopenia syndrome, including heparin-induced thrombocytopenia, vaccine-induced immune thrombotic thrombocytopenia, paroxysmal nocturnal hemoglobinuria, antiphospholipid syndrome, thrombotic microangiopathy (TMA), and disseminated intravascular coagulation. TMA includes thrombotic thrombocytopenic purpura, Shiga toxin-producing Escherichia coli-associated hemolytic uremic syndrome (HUS), and atypical HUS. Patients with these pathologies present with thrombosis and consumptive thrombocytopenia associated with the activation of platelets and the coagulation system. Treatment varies from disease to disease, and many diseases have direct impacts on mortality and organ prognosis if therapeutic interventions are not promptly implemented. Underlying diseases and the results of physical examinations and general laboratory tests as part of a thorough workup for patients should promptly lead to therapeutic intervention before definitive diagnosis. For some diseases, the diagnosis and initial treatment must proceed in parallel. Utilization of not only laboratory tests but also various scoring systems is important for validating therapeutic interventions based on clinical information.

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.