Thrombotic thrombocytopenic purpura (TTP) is a rare and life-threatening thrombotic microangiopathy characterized by microangiopathic hemolytic anemia, severe thrombocytopenia, and organ ischemia ...linked to disseminated microvascular platelet rich-thrombi. TTP is specifically related to a severe deficiency in ADAMTS13 (a disintegrin and metalloprotease with thrombospondin type 1 repeats, member 13), the specific von Willebrand factor-cleaving protease. ADAMTS13 deficiency is most frequently acquired via ADAMTS13 autoantibodies, but rarely, it is inherited via mutations of the ADAMTS13 gene. The first acute episode of TTP usually occurs during adulthood, with a predominant anti-ADAMTS13 autoimmune etiology. In rare cases, however, TTP begins as soon as childhood, with frequent inherited forms. TTP is ∼2-fold more frequent in women, and its outcome is characterized by a relapsing tendency. Rapid recognition of TTP is crucial to initiate appropriate treatment. The first-line therapy for acute TTP is based on daily therapeutic plasma exchange supplying deficient ADAMTS13, with or without steroids. Additional immune modulators targeting ADAMTS13 autoantibodies are mainly based on steroids and the humanized anti-CD20 monoclonal antibody rituximab. In refractory or unresponsive TTP, more intensive therapies including twice-daily plasma exchange; pulses of cyclophosphamide, vincristine, or cyclosporine A; or salvage splenectomy are considered. New drugs including N-acetylcysteine, bortezomib, recombinant ADAMTS13, and caplacizumab show promise in the management of TTP. Also, long-term follow-up of patients with TTP is crucial to identify the occurrence of other autoimmune diseases, to control relapses, and to evaluate psychophysical sequelae. Further development of both patients' registries worldwide and innovative drugs is still needed to improve TTP management.
Objective
Because it has no unique clinical, biologic, or histologic features, reactive hemophagocytic syndrome may be difficult to distinguish from other diseases such as severe sepsis or ...hematologic malignancies. This study was undertaken to develop and validate a diagnostic score for reactive hemophagocytic syndrome.
Methods
A multicenter retrospective cohort of 312 patients who were judged by experts to have reactive hemophagocytic syndrome (n = 162), were judged by experts to not have reactive hemophagocytic syndrome (n = 104), or in whom the diagnosis of reactive hemophagocytic syndrome was undetermined (n = 46) was used to construct and validate the reactive hemophagocytic syndrome diagnostic score, called the HScore. Ten explanatory variables were evaluated for their association with the diagnosis of hemophagocytic syndrome, and logistic regression was used to calculate the weight of each criterion included in the score. Performance of the score was assessed using developmental and validation data sets.
Results
Nine variables (3 clinical i.e., known underlying immunosuppression, high temperature, organomegaly, 5 biologic i.e., triglyceride, ferritin, serum glutamic oxaloacetic transaminase, and fibrinogen levels, cytopenia, and 1 cytologic i.e., hemophagocytosis features on bone marrow aspirate) were retained in the HScore. The possible number of points assigned to each variable ranged from 0–18 for known underlying immunosuppression to 0–64 for triglyceride level. The median HScore was 230 (interquartile range IQR 203–257) for patients with a positive diagnosis of reactive hemophagocytic syndrome and 125 (IQR 91–150) for patients with a negative diagnosis. The probability of having hemophagocytic syndrome ranged from <1% with an HScore of ≤90 to >99% with an HScore of ≥250.
Conclusion
The HScore can be used to estimate an individual's risk of having reactive hemophagocytic syndrome. This scoring system is freely available online (http://saintantoine.aphp.fr/score/).
In acquired thrombotic thrombocytopenic purpura (TTP), an immune-mediated deficiency of the von Willebrand factor-cleaving protease ADAMTS13 allows unrestrained adhesion of von Willebrand factor ...multimers to platelets and microthrombosis, which result in thrombocytopenia, hemolytic anemia, and tissue ischemia. Caplacizumab, an anti-von Willebrand factor humanized, bivalent variable-domain-only immunoglobulin fragment, inhibits interaction between von Willebrand factor multimers and platelets.
In this double-blind, controlled trial, we randomly assigned 145 patients with TTP to receive caplacizumab (10-mg intravenous loading bolus, followed by 10 mg daily subcutaneously) or placebo during plasma exchange and for 30 days thereafter. The primary outcome was the time to normalization of the platelet count, with discontinuation of daily plasma exchange within 5 days thereafter. Key secondary outcomes included a composite of TTP-related death, recurrence of TTP, or a thromboembolic event during the trial treatment period; recurrence of TTP at any time during the trial; refractory TTP; and normalization of organ-damage markers.
The median time to normalization of the platelet count was shorter with caplacizumab than with placebo (2.69 days 95% confidence interval {CI}, 1.89 to 2.83 vs. 2.88 days 95% CI, 2.68 to 3.56, P=0.01), and patients who received caplacizumab were 1.55 times as likely to have a normalization of the platelet count as those who received placebo. The percentage of patients with a composite outcome event was 74% lower with caplacizumab than with placebo (12% vs. 49%, P<0.001). The percentage of patients who had a recurrence of TTP at any time during the trial was 67% lower with caplacizumab than with placebo (12% vs. 38%, P<0.001). Refractory disease developed in no patients in the caplacizumab group and in three patients in the placebo group. Patients who received caplacizumab needed less plasma exchange and had a shorter hospitalization than those who received placebo. The most common adverse event was mucocutaneous bleeding, which was reported in 65% of the patients in the caplacizumab group and in 48% in the placebo group. During the trial treatment period, three patients in the placebo group died. One patient in the caplacizumab group died from cerebral ischemia after the end of the treatment period.
Among patients with TTP, treatment with caplacizumab was associated with faster normalization of the platelet count; a lower incidence of a composite of TTP-related death, recurrence of TTP, or a thromboembolic event during the treatment period; and a lower rate of recurrence of TTP during the trial than placebo. (Funded by Ablynx; HERCULES ClinicalTrials.gov number, NCT02553317 .).
Background
Despite an increase in our understandings of pathogenesis of thrombotic thrombocytopenic purpura (TTP), the approaches for initial diagnosis and management of TTP vary significantly.
...Objective
The evidence‐based guidelines of the International Society on Thrombosis and Haemostasis (ISTH) are intended to support patients, clinicians, and other health care professionals in their decisions about the initial diagnosis and management of acute TTP.
Methods
In June 2018, ISTH formed a multidisciplinary panel that included hematologists, an intensive care physician, nephrologist, clinical pathologist, biostatistician, and patient representatives, as well as a methodology team from McMaster University. The panel composition was designed to minimize the potential conflicts of interests. The panel used the Grading of Recommendations Assessment, Development, and Evaluation approach and the Population, Intervention, Comparison, Outcome framework to develop and grade their recommendations. Public comments were sought and incorporated in the final document.
Results
The panel agreed on three recommendations covering the initial diagnosis with emphasis on the importance of ADAMTS13 testing (eg, activity, anti‐ADAMTS13 IgG or inhibitor) and assessment of the pretest probability of TTP by clinical assessment and/or the risk assessment models like the PLASMIC or French score. The panel noted how availability and turnaround time of ADAMTS13 test results might affect early diagnosis and management, in particular the use of caplacizumab.
Conclusions
There is a lack of high‐quality evidence to support strong recommendations for the initial diagnosis and management of a suspected TTP. The panel emphasized the importance of obtaining ADAMTS13 testing in a proper clinical context. Future research should focus on how to monitor and act on ADAMTS13 levels during remission.
Abstract Objectives Current knowledge in reactive hemophagocytic syndrome mainly relies on single-center case series including a relatively small number of patients. We aimed to identify a ...multicenter large cohort of adult patients with reactive hemophagocytic syndrome and to describe relevant clinical and laboratory features, underlying conditions, and outcome. Methods We conducted a multicenter study in 3 tertiary care centers in France over a 6-year period. The medical files of 312 patients with suspected hemophagocytic syndrome were retrospectively reviewed. Patients were classified with a positive, negative, or undetermined diagnosis of hemophagocytic syndrome by experts' consensus. Results Among the 312 patients fulfilling our inclusion criteria, 162 were classified with positive hemophagocytic syndrome (male, 67%; median age, 48 35-62 years). Compared with patients without hemophagocytic syndrome, patients with hemophagocytic syndrome more frequently had an underlying immunodepression (45% vs 33%, P = .03) and exhibited higher temperature, ferritin, triglycerides, aspartate transaminase, bilirubin, lactate dehydrogenase, and C-reactive protein, and lower hemoglobin, leukocytes, platelets, and sodium levels. Only 70% of them had hemophagocytosis features on bone marrow aspiration. Hematologic malignancies, especially non-Hodgkin lymphomas, were the main trigger of hemophagocytic syndrome, accounting for 56% of cases. The early mortality rate (ie, within 1 month after diagnosis) was 20%. Patients with hematologic malignancies-associated hemophagocytic syndrome had a poorer early outcome than those with underlying infection. Conclusions In this large, multicenter study, hematologic malignancies are the main disease associated with hemophagocytic syndrome in adults. Early mortality is high, and outcome is influenced by the underlying disease.
Preemptive rituximab infusions prevent relapses in immune thrombotic thrombocytopenic purpura (iTTP) by maintaining normal ADAMTS13 activity. However, the long-term outcome of these patients and the ...potential adverse events of this strategy need to be determined. We report the long-term outcome of 92 patients with iTTP in clinical remission who received preemptive rituximab after identification of severe ADAMTS13 deficiency (activity <10%) during the follow-up. Thirty-seven patients had >1 iTTP episode, and the median cumulative relapse incidence before preemptive rituximab was 0.33 episode per year (interquartile range IQR, 0.23-0.66). After preemptive rituximab, the median cumulative relapse incidence in the whole population decreased to 0 episodes per year (IQR, 0-1.32; P < .001). After preemptive rituximab, ADAMTS13 activity recovery was sustained in 34 patients (37%) during a follow-up of 31.5 months (IQR, 18-65), and severe ADAMTS13 deficiency recurred in 45 patients (49%) after the initial improvement. ADAMTS13 activity usually improved with additional courses of preemptive rituximab. In 13 patients (14%), ADAMTS13 activity remained undetectable after the first rituximab course, but retreatment was efficient in 6 of 10 cases. In total, 14 patients (15%) clinically relapsed, and 19 patients (20.7%) experienced benign adverse effects. Preemptive rituximab treatment was associated with a change in ADAMTS13 conformation in respondent patients. Finally, in the group of 23 historical patients with iTTP and persistently undetectable ADAMTS13 activity, 74% clinically relapsed after a 7-year follow-up (IQR, 5-11). In conclusion, persistently undetectable ADAMTS13 activity in iTTP during remission is associated with a higher relapse rate. Preemptive rituximab reduces clinical relapses by maintaining a detectable ADAMTS13 activity with an advantageous risk-benefit balance.
•TTP patients who display persistent and severe ADAMTS13 deficiency after remission have a relapse rate of 74% during long-term follow-up.•Preemptive rituximab can decrease TTP relapses in 85% of patients with a favorable benefit-risk balance.
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In acquired thrombotic thrombocytopenic purpura (TTP), the persistence of severe ADAMTS13 deficiency (<10%) during remission is associated with more relapse. Preemptive (ie, after remission) ...administration of rituximab in these patients to prevent relapses remains controversial. We performed a cross-sectional analysis of 12-year follow-up data to compare the relapse incidence with or without preemptive rituximab infusion. Among 48 patients who experienced at least one episode of acquired TTP followed by severe ADAMTS13 deficiency during remission, 30 received preemptive rituximab (group 1); the other 18 did not (group 2). After a median of 17 months (interquartile range IQR, 11-29) following rituximab, the relapse incidence decreased from 0.57 episodes/year (IQR, 0.46-0.7) to 0 episodes/year (IQR, 0-0.81) (P < .01) in group 1. ADAMTS13 activity 3 months after the first rituximab infusion increased to 46% (IQR, 30%-68%). Nine patients required additional courses of rituximab. In 5 patients, ADAMTS13 activity failed to increase durably. Four patients experienced manageable adverse effects. In group 2, the relapse incidence was higher (0.5 relapses/year; IQR, 0.12-0.5; P < .01). Relapse-free survival was longer in group 1 (P = .049). A persistent severe ADAMTS13 deficiency during TTP remission should prompt consideration of preemptive rituximab to prevent relapses.
•Patients with a history of acquired TTP and persistent severe ADAMTS13 deficiency during remission are at high risk of relapse and death.•Preemptive infusions of rituximab in remission significantly decrease TTP relapse rate.
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