Thrombotic Microangiopathies

Hematopoietic stem cell transplant (HSCT) is an effective but toxic therapy and pulmonary morbidity affects as many as 25% of children receiving transplant. Early pulmonary injury includes diffuse alveolar hemorrhage (DAH), thrombotic microangiopathy (TMA) interstitial pneumonitis (IPS) and infection, while later, bronchiolitis obliterans is a complication of chronic GVHD associated with severe morbidity and mortality. Improved diagnosis and treatment of pulmonary complications are urgently needed as survival after HSCT improves, and as HSCT is increasingly used for non-malignant disorders such as sickle cell disease. Currently, there are large and important gaps in the investigator's knowledge regarding incidence, etiology and optimal treatment of pulmonary complications. Moreover, young children unable to perform spirometry are often diagnosed late, and strategies for monitoring therapeutic response are limited. This is a prospective multi-institutional cohort study in pediatric patients undergoing allogeneic hematopoietic stem cell transplantation (alloHSCT). Assembly of a large prospective uniformly screened cohort of children receiving HSCT, together with collection of biological samples, will be an effective strategy to identify mechanisms of lung injury, test novel diagnostic strategies for earlier diagnosis, and novel treatments to reduce morbidity and mortality from lung injury after transplant.

This is a Phase 1/2, prospective, adaptive design trial of TGD001 in participants with suspicion or clinical diagnosis of acute immune thrombotic thrombocytopenic purpura (iTTP) episodes and participants with suspicion or clinical diagnosis of an acute Thrombotic Microangiopathy (TMA) episode. The trial is an open-label, dose escalation and expansion basket trial.

Immune thrombotic thrombocytopenic purpura (iTTP) is caused by a severe, autoantibody-mediated deficiency of ADAMTS13 leading to an accumulation of ultra-large von Willebrand factor multimers in plasma and finally to microthrombi in blood vessels. The current standard of care of iTTP consists in the triple association of daily plasma exchange (PEX, 60 ml/kg/day), immunosuppressive agents and anti-adhesive treatment (Caplacizumab). Our group recently reported the outcome of 90 patients with iTTP treated with this triple association and when compared to historical patients, the triplet regimen prevented death, refractoriness and exacerbations. Likewise, plasma volumes were reduced by 2 to 3-fold and the median number of PEX sessions could be reduced from 13 to 6. PEX is an invasive and time-consuming procedure, associated with catheter and plasma-related complications ranging from 22% to 30%. Consequently, to alleviate the burden of care in iTTP, using a regimen without PEX would represent a major and topical goal. Attempts to treat patients with plasma infusion (PI) without PEX were previously reported and provided evidence that large volumes of PI (20-30 ml/kg/day) improved the initial outcome of iTTP. However, fluid overload occurred in most cases after 5-7 days, limiting the feasibility of this strategy. Nevertheless, the recent availability of caplacizumab opens the perspective of treating patients with plasma for a shorter period. Recently, strategies without PEX have been carried out in Jehovah's Witnesses with iTTP \[5\]. Impressively, improvement was rapid and comparable to those provided with a standard PEX-based treatment. Additionally, a treatment combining caplacizumab and immunosuppression only was successfully performed in six iTTP patients with severe neurologic and/or cardiac involvement. The rapid and durable improvement provides evidence that a regimen without plasma seems feasible. However, it's considered that robust data are still lacking to completely remove plasmatherapy from iTTP management. Based on these statements, the objective is to address the efficacy and safety of a PEX-free regimen, combining PI only (15 ml/kg/day), corticosteroids/rituximab, and caplacizumab.

Immune thrombotic thrombocytopenic purpura (iTTP) is a rare, life-threatening disorder characterized by microangiopathic hemolytic anemia, severe thrombocytopenia, and ischemic organ damage due to microvascular thrombosis. It results from a severe deficiency in the von Willeband factor (vWF)-cleaving protease ADAMTS13, primarily caused by autoantibodies that inhibit its activity. This deficiency leads to accumulation of ultra-large vWF multimers, triggering pathological platelet aggregation and widespread microthrombi. iTTP typically presents with acute neurological symptoms (e.g., confusion, seizures, coma), cardiac events (e.g., myocardial infarction), and multiorgan dysfunction. Without prompt treatment-plasma exchange, immunosuppression, and the vWF inhibitor caplacizumab-mortality exceeds 90%. Survivors face long-term risks, including cardiovascular complications, cognitive impairment, and reduced life expectancy. The TWI-LIGHT protocol is a national retrospective epidemiological study coordinated by the French Reference Center for Thrombotic Microangiopathies (CNR-MAT). It aims to analyze long-term outcome in \>1,200 iTTP patients diagnosed between October 2000 and June 2024. The study leverages pseudonymized data from the CNR-MAT registry, collected via a secure REDCap database. Key Objectives: 1. Primary: Assess the impact of cardiovascular risk factors (e.g., hypertension, diabetes) and ADAMTS13 activity on life expectancy in iTTP survivors. 2. Secondary: * Evaluate disease burden in underrepresented groups (pregnant/postpartum women, children, elderly patients). * Analyze the influence of new therapies (caplacizumab, rituximab, recombinant ADAMTS13) on care pathways. * Identify prognostic factors and treatment practices. * Characterize neurocognitive outcomes and quality of life post-iTTP. Methodology: * Design: Non-interventional, retrospective (MR-004 compliance), using data from standard care. * Inclusion: Patients with confirmed iTTP (thrombocytopenia, hemolytic anemia, ADAMTS13 \<10%), diagnosed within the study period, and ≥1 year of follow-up. * Exclusion: Cancer-associated iTTP, severe sepsis, or patient opposition to data reuse. * Data Collection: Clinical, biological, and therapeutic variables from hospital/consultation records, including cardiovascular events, ADAMTS13 activity, and neurocognitive assessments. * Analysis: Kaplan-Meier survival curves and Cox regression models to identify risk factors for non-iTTP-related death. Expected Outcomes: * Prevalence of cardiovascular comorbidities and their correlation with ADAMTS13 activity. * Insights into iTTP subtypes (e.g., gestational, pediatric) and therapeutic efficacy. * Evidence-based strategies for personalized long-term management. Ethical Framework: * AP-HP-sponsored, with oversight from Sorbonne University's ethics committee. * Patients informed of data reuse with opt-out rights; data archived for 15 years. This landmark study will inform clinical guidelines, optimize survivor care, and address unmet needs in iTTP management through comprehensive, real-world data analysis.

Thrombotic microangiopathy (TMA) is a severe and life-threatening condition, often affecting the kidneys and brain. It can occur on the background of various clinical conditions. Dysregulation of the alternative pathway of complement may be the etiological factor and this type of TMA is classified, according to the current nomenclature, as primary atypical hemolytic uremic syndrome (HUS). Half the patients with primary atypical HUS present with rare variants in complement genes, although coexisting conditions are often needed for the TMA to become manifest. In patients with secondary atypical HUS, certain coexisting conditions appear to drive the disease and treatment should target the underlying condition to remit the TMA. Recently, the investigators demonstrated, by using a novel in-house developed functional endothelial cell-based test, that complement dysregulation and overactivation is the dominant cause of disease and its sequelae in a subset of patients with secondary atypical HUS, having impact on treatment and prognosis. The investigators did first prove this concept in patients presenting with TMA and hypertensive emergency. A prospective study is needed to further corroborate these findings along the spectrum of TMA. The investigators hypothesize that their functional endothelial cell-based test, the so-called "HMEC" test, can better categorizes the TMA into different groups with potential therapeutic and prognostic implications. Thus, paving the road to the ultimate goal of precision medicine.

The goal of this clinical trial is to learn about plasma biomarkers of diagnosed transplant-associated thrombotic microangiopathy (TA-TMA) in patients undergoing transplantation. The main questions it aims to answer are: whether there are molecules that can accurately diagnose and predict TA-TMA; whether the current biomarkers related to TA-TMA can well predict the occurrence and survival of TA-TMA in adult patients with malignant hematopoietic diseases, for example, acute leukemia. Participants will receive laboratory tests of peripheral blood and urine specimens related to TA-TMA at regular times after transplantation.

The purpose of this study is to evaluate the safety and efficacy of narsoplimab in pediatric patients with thrombotic microangiopathies (TMA) following hematopoietic stem cell transplant (HSCT).

This is a multicenter, prospective, longitudinal, observational cohort study to investigate thrombosis and hemostasis diseases in Chinese patients. This study will collect basic information, diagnostic and treatment information, as well as medical expense information of patients from medical records.The incidence and risk factors of thrombosis and hemostasis diseases, the treatment methods, prognosis and medical expenses of these patients in China will be analyzed. The study will use questionnaire to measure the exposure of patients, and prospectively follow-up to collect the prognosis information.

Information about patients was collected by reviewing the Hitech case system and telephone and outpatient follow-up, and the case database was constructed by Epidata software. The sample size is expected to be 200 cases, the participating hospital is the First Affiliated Hospital of Soochow University, and the study time frame is from Dec 1, 2022, to Nov 31, 2027. The observation indexes of the study include the basic information of patients' age and gender and the clinical-related data of thrombotic microangiopathy.