ADAMTS13 recovery in acute thrombotic thrombocytopenic purpura after caplacizumab therapy

ABSTRACT

Caplacizumab prevents the interaction between von Willebrand factor and platelets and is used to treat immune thrombotic thrombocytopenic purpura (iTTP). Its administration has been associated with a delay in ADAMTS13 activity restoration after plasma exchange (PEX) suspension. We analyzed the outcomes of 113 iTTP episodes, 75 of which were treated with caplacizumab, in 108 patients from the Spanish Registry of Thrombotic Thrombocytopenic Purpura. Caplacizumab shortened the time to platelet count normalization and reduced PEX requirement, exacerbations, and relapses. There was no difference in the time to achieve ADAMTS13 activity ≥20% after PEX end between caplacizumab-treated and nontreated episodes (median [interquartile range], 14.5 [7.7-27.2] vs 13.0 [8.0-29.0] days, P = .653). However, considering the 36 episodes in which caplacizumab was started ≤3 days after iTTP diagnosis, the time for ADAMTS13 restoration from PEX end was higher than in those episodes in which caplacizumab was started >3 days after iTTP diagnosis (20.0 [12.0-43.0] vs 11.0 [3.5-20.0] days, P = .003) or than in non-caplacizumab-treated episodes (P = .033). This finding could be related to a significantly shorter duration of PEX in early caplacizumab-treated episodes than in late caplacizumab-treated episodes (5.5 [4.0-9.0] vs 15.0 [11.0-21.5] days, P < .001) or non-caplacizumab-treated episodes (11.0 [6.0-26.0] days, P < .001). There were no differences in time to ADAMTS-13 restoration from PEX start (28.0 [17.2-47.5], 27.0 [19.0-37.5] and 29.5 [15.2-45.0] days in early caplacizumab-treated, late caplacizumab-treated and non-caplacizumab-treated episodes). Early administered caplacizumab does not prevent the requirement for immunosuppression but has beneficial effects by shortening PEX requirement without major safety concerns.

Recommendations for the Clinical Approach to Immune Thrombocytopenia: Spanish ITP Working Group (GEPTI)

Primary immune thrombocytopenia (ITP) is a complex autoimmune disease whose hallmark is a deregulation of cellular and humoral immunity leading to increased destruction and reduced production of platelets. The heterogeneity of presentation and clinical course hampers personalized approaches for diagnosis and management. In 2021, the Spanish ITP Group (GEPTI) of the Spanish Society of Hematology and Hemotherapy (SEHH) updated a consensus document that had been launched in 2011. The updated guidelines have been the reference for the diagnosis and management of primary ITP in Spain ever since. Nevertheless, the emergence of new tools and strategies makes it advisable to review them again. For this reason, we have updated the main recommendations appropriately. Our aim is to provide a practical tool to facilitate the integral management of all aspects of primary ITP management.

Immune thrombotic thrombocytopenic purpura: clinical suspicion and basic management in emergency departments - an expert review and consensus statement from the Spanish societies of hematology and hemotherapy (SEHH) and emergency medicine (SEMES)

TEXT

Acquired or immune thrombotic thrombocytopenic purpura (TTP) are thrombotic microangiopathies associated with high mortality if treatment is not started early. Onset is usually sudden, meaning that the condition is often diagnosed in hospital emergency departments, where TTP must be suspected as early as possible. These guidelines were drafted by specialists in emergency medicine and hematology to cover the diagnosis, referral, and treatment of patients suspected of immune-mediated TTP who require emergency care. Immune TTP should be suspected whenever a patient presents with hemolytic microangiopathy and has a negative Coombs test, and thrombocytopenia, possibly in conjunction with fever and neurologic and cardiac alterations. If one of the existing diagnostic algorithms indicates there is a high probability that the patient has immune TTP, plasma exchange therapy should be started along with immunosuppressants. Treatment with caplacizumab should also be considered. The patient should be referred immediately to the hematology department within the same hospital or a referral hospital.

COVID-19 Vaccines and Autoimmune Hematologic Disorders

Worldwide vaccination against SARS-CoV-2 has allowed the detection of hematologic autoimmune complications. Adverse events (AEs) of this nature had been previously observed in association with other vaccines. The underlying mechanisms are not totally understood, although mimicry between viral and self-antigens plays a relevant role. It is important to remark that, although the incidence of these AEs is extremely low, their evolution may lead to life-threatening scenarios if treatment is not readily initiated. Hematologic autoimmune AEs have been associated with both mRNA and adenoviral vector-based SARS-CoV-2 vaccines. The main reported entities are secondary immune thrombocytopenia, immune thrombotic thrombocytopenic purpura, autoimmune hemolytic anemia, Evans syndrome, and a newly described disorder, so-called vaccine-induced immune thrombotic thrombocytopenia (VITT). The hallmark of VITT is the presence of anti-platelet factor 4 autoantibodies able to trigger platelet activation. Patients with VITT present with thrombocytopenia and may develop thrombosis in unusual locations such as cerebral beds. The management of hematologic autoimmune AEs does not differ significantly from that of these disorders in a non-vaccine context, thus addressing autoantibody production and bleeding/thromboembolic risk. This means that clinicians must be aware of their distinctive signs in order to diagnose them and initiate treatment as soon as possible.

A mild deficiency of ADAMTS13 is associated with severity in COVID-19: comparison of the coagulation profile in critically and noncritically ill patients

Early descriptions of COVID-19 associated coagulopathy identified it as a disseminated intravascular coagulation (DIC). However, recent studies have highlighted the potential role of endothelial cell injury in its pathogenesis, and other possible underlying mechanisms are being explored. This study aimed to analyse the coagulation parameters of critically and noncritically ill patients with COVID-19 bilateral pneumonia, determine if coagulation factors consumption occurs and explore other potential mechanisms of COVID-19 coagulopathy. Critically and noncritically ill patients with a diagnosis of COVID-19 bilateral pneumonia were recruited. For each patient, we performed basic coagulation tests, quantification of coagulation factors and physiological inhibitor proteins, an evaluation of the fibrinolytic system and determination of von Willebrand Factor (vWF) and ADAMTS13. Laboratory data were compared with clinical data and outcomes. The study involved 62 patients (31 ICU, 31 non-ICU). The coagulation parameters assessment demonstrated normal median prothrombin time (PT), international normalized ratio (INR) and activated partial thromboplastin time (APTT) in our cohort and all coagulation factors were within normal range. PAI-1 median levels were elevated (median 52.6 ng/ml; IQR 37.2-85.7), as well as vWF activity (median 216%; IQR 196-439) and antigen (median 174%; IQR 153.5-174.1). A mild reduction of ADAMTS13 was observed in critically ill patients and nonsurvivors. We demonstrated an inverse correlation between ADAMTS13 levels and inflammatory markers, D-dimer and SOFA score in our cohort. Elevated vWF and PAI-1 levels, and a mild reduction of ADAMTS13 in the most severe patients, suggest that COVID-19 coagulopathy is an endotheliopathy that has shared features with thrombotic microangiopathy.

Incidence, characteristics and clinical profile of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in patients with pre-existing primary immune thrombocytopenia (ITP) in Spain

Infections are one of the well-known precipitating factors for relapses in patients with immune thrombocytopenia (ITP). Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection can sometimes lead to or be associated with thrombocytopenia due to an increase in peripheral platelet destruction from inflammatory hyperactivation. Currently, we do not know if SARS-CoV-2 infection modifies the natural evolution of chronic or persistent ITP or if previous immunosuppression of patients with ITP influences the incidence and severity of coronavirus disease 2019 (COVID-19) in this group. The present study was an observational, multicentre, national series of 32 adult patients with pre-existing ITP and subsequent SARS-CoV-2 infection, collected by the Spanish ITP Group [Grupo Español de Trombocitopenia Inmune (GEPTI)].

Incidence, diagnosis, and outcome of immune-mediated thrombotic thrombocytopenic purpura: A nationwide survey by the Spanish registry of thrombotic thrombocytopenic purpura

BACKGROUND

Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare disease characterized by the presence of anti-ADAMTS13 autoantibodies. Achieving accurate information on incidence and customary disease management is important to provide appropriate diagnostic and therapeutic resources. The aim of this study was to determine the incidence and outcomes of iTTP in Spain.

STUDY DESIGN AND METHODS

A cross-sectional survey was carried out among Spanish hospitals, focused on iTTP patients ≥16 years old attended between 2015 and 2017, and those at follow-up before that interval. Incidence, prevalence, mortality, refractoriness, exacerbations, treatment complications, relapses, and sequelae were estimated.

RESULTS

Forty-two hospitals covering roughly 20 million inhabitants answered the survey and reported 203 episodes (138 newly-diagnosed and 65 relapses), of which 193 (95.1%) were treated. Incidence was 2.67 (95% CI 1.90-3.45) patients per million inhabitants per year and prevalence 21.44 (95% CI% 19.10-23.73) patients per million inhabitants. At diagnosis, ADAMTS13 activity and anti-ADAMTS13 autoantibody were measured in 97% and 84.3% of reported episodes, respectively. Fifteen patients (7.4%) died as a direct consequence of iTTP, 6 of them before receiving any iTTP-specific treatment. Thirty-one (16.1%) of the 193 treated episodes were refractory to plasma exchange and corticosteroids, and 51 (26.4%) suffered at least one exacerbation.

CONCLUSION

iTTP incidence and prevalence were somewhat higher than those documented in neighboring countries. Together with data on treatments and outcomes, this information will allow us to better estimate what is needed to improve diagnosis and prognosis of iTTP patients in Spain.

Application of the French TMA Reference Center Score and the mortality in TTP Score in de novo and relapsed episodes of acquired thrombotic thrombocytopenic purpura at a tertiary care facility in Spain

Acquired thrombotic thrombocytopenic purpura (aTTP) is still associated with a 10% to 20% death rate and its clinical course is characterized by recurrent episodes in up to 50% of cases. Over the last decade, mortality predicting models like the French TMA Reference Center Score and the Mortality In TTP Score (MITS) have been developed in an attempt to personalize treatment. The objective of the present study was to compare the results in both scores of de novo and relapsed aTTP episodes. For such purpose, a total of 29 episodes of aTTP (16 de novo and 13 relapses) were analyzed. All patients were homogeneously diagnosed and treated. First episodes had a higher score in both models in comparison with relapsed aTTP, (MITS median, 1 r: 1-4 vs 0 r: 1-2, P = .038 and French TMA Reference Center Score median, 2 r: 1-3 vs 1 r: 0-1, P = .006). The prevalence of neurological symptoms was significantly higher in the first episodes (P = .001) and patients >60 years old were more common in this group (P = .013), which may have been related to the results. Platelet count at presentation was higher in recurrences than in the first disease episode (P = .016) and ADAMTS13 activity <5% was more frequent in the last group (P = .016). There was no significant difference in the rate of refractoriness or exacerbations. In conclusion, first aTTP episodes had a higher probability of short-term mortality compared to relapsed aTTP episodes according to the MITS and French TMA Reference Center Score.

Level of concordance between two risk-assessment models for predicting venous thromboembolism in medical patients at admission

Objectives

To evaluate the level of concordance between the 2007 PRETEMED guidelines and the 2012 American College of Chest Physicians (ACCP) guidelines in medical patients at admission.

Methods

A cross-sectional, observational and descriptive study was designed and included all adult medical patients admitted from an emergency department. Firstly, patients classified as low-moderate risk and high risk according to PRETEMED were compared to those classified by ACCP as low and high risk. Secondly, the same analysis was performed but this time low and moderate-high risk patients according to PRETEMED were compared to ACCP low and high risk patients. The level of concordance was calculated using the kappa concordance index. The study was approved by the Ethics Committee for Clinical Research of the hospital.

Results

The analysis was performed with 207 patients; 53.1% were male and the median age was 75.3 years (minimum 18, maximum 100 years old). The most common diagnosis at admission was related to a respiratory disease (37.2%). The level of concordance was 0.59 (95% CI 0.48 to 0.70) when moderate risk patients were grouped with low-risk patients and 0.53 (95% CI 0.42 to 0.65) when moderate risk patients were grouped with high-risk patients.

Conclusions

The level of concordance between both guides is moderate. It would be helpful to confirm whether the level of agreement improves when the patient's condition stabilises after several days of hospitalisation.