UNASSIGNED: Thrombotic microangiopathy (TMA) is characterized by thrombocytopenia, microangiopathic hemolytic anemia and target organ damage. Pregnancy is associated with several forms of TMA, including preeclampsia (PE), HELLP syndrome, thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS). When HUS is secondary to a deregulation of the alternative complement pathway, it is known as atypical HUS (aHUS). Differential diagnosis is challenging, as these forms share clinical characteristics. However, early diagnosis is crucial for a specific treatment to be established and improve prognosis.
UNASSIGNED: We present the case of a 43 year-old primiparous woman admitted to hospital for an urgent C-section at 33 gestational weeks due to a diagnosis of severe preeclampsia and fetal distress. In the immediate postpartum, the patient developed acute liver failure and anuric renal failure in the context of the HELLP syndrome, anemia, thrombocytopenia, arterial hypertension (HTN) and neurological deficit. TMA study and differential diagnosis confirmed pregnancy-associated aHUS. Treatment with eculizumab was initiated, with good response and progressive improvement of clinical and analytical parameters.
UNASSIGNED: aHUS is a rare multifactorial disease that used to be associated with high mortality rates before the advent of eculizumab. Due to challenging diagnosis, the clinical laboratory plays a major role in the differential diagnosis and management of the disease.

UNASSIGNED: Transplant-associated thrombotic microangiopathy (TA-TMA) is a fatal complication of hematopoietic stem cell transplantation and is characterized by severe thrombocytopenia, hemolytic anemia, and organ dysfunction. In response to several possible triggers, dynamic multimetric change in von Willebrand factor (VWF) may contribute to inducing microthrombi in circulation in TA-TMA.
UNASSIGNED: By performing VWF multimer analysis and measuring VWF-degradation product (DP), we unraveled the relationship between multimeric changes in circulating VWF and the pathogenesis of TA-TMA.
UNASSIGNED: This study analyzed 135 plasma samples from 14 patients who underwent allogeneic hematopoietic stem cell transplantation at a single institute. VWF-associated markers, namely VWF:antigen (VWF:Ag), VWF-DP/VWF:Ag ratio, VWF:ristocetin cofactor activity, VWF:ristocetin cofactor activity/VWF:Ag ratio, and ADAMTS13 activity, were analyzed in these samples collected every 7 days.
UNASSIGNED: There were 2 patients with definite thrombotic microangiopathy (TMA) and 6 patients who presented with probable TMA that did not progress to definite TMA. Each plasma sample was classified into 3 groups: definite TMA, probable TMA, and non-TMA. VWF multimer analysis showed the absence of high-molecular-weight VWF multimers in probable TMA, whereas the appearance of unusually large VWF multimers was observed in definite TMA. The median value of the VWF-DP/VWF:Ag ratio in probable TMA was elevated to 4.17, suggesting that excessive cleavage of VWF multimers by VWF cleaving enzyme, ADAMTS13, resulted in the loss of high-molecular-weight VWF multimers.
UNASSIGNED: During the transition from probable to definite TMA, drastic VWF multimer changes imply a switch from bleeding to thrombotic tendencies. Extensive VWF-DP and VWF multimer analyses provided novel insights.

BACKGROUND: Sunitinib, a multi-targeted tyrosine kinase inhibitor, is used as a second-line therapy for gastrointestinal stromal tumors (GIST) resistant to imatinib. However, its impact on the vascular endothelial growth factor (VEGF) pathway can lead to significant toxicities, including hypertension and thrombotic microangiopathy (TMA).
METHODS: This case report describes a unique instance of a patient with metastatic GIST who developed endocapillary proliferative glomerulonephritis (EPGN) with IgA2 deposits and TMA following sunitinib treatment. The patient presented with severe hypertension, nephrotic syndrome, and acute kidney injury. Renal biopsy confirmed the diagnosis, revealing IgA2 deposits, which are not commonly associated with TMA. Discontinuation of sunitinib led to a rapid improvement in renal function and proteinuria. The potential mechanisms underlying sunitinib-induced glomerular injury may involve the blockade of VEGFR-1, affecting immune cell recruitment and function, and the disruption of the nitric oxide and endothelin systems, leading to endothelial damage and immune dysregulation. Management of these toxicities requires a personalized approach, with options ranging from symptomatic relief to drug discontinuation. The use of endothelin receptor antagonists and other therapeutic alternatives for GIST management is discussed.
CONCLUSIONS: This case highlights the complex interplay between the therapeutic effects of sunitinib and its potential renal and cardiovascular toxicities, emphasizing the need for close monitoring and effective management strategies to optimize patient outcomes.

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.

Thrombotic microangiopathy (TMA) is a rare renal complication of patients with chronic lymphocytic leukemia (CLL) and is often associated with peripheral features. We present the first case of CLL patients with renal-limited TMA. A 70-year-old female patient with a history of well-controlled type 2 diabetes and baseline albuminuria of 87.2 mg/g 1 year prior and CLL was on active surveillance only. Her baseline white blood cell (WBC) was 202.6 x 103/µl. She presented with nephrotic syndrome with proteinuria of 10 g/g and a subsequent unremarkable serologic work-up. A kidney biopsy revealed diabetic glomerulosclerosis and chronic TMA. Initially, she was treated conservatively with angiotensin receptor blockade and sodium glucose cotransporter-2 inhibition but progressed with increased proteinuria of 17 g/g. Complement functional panel testing was pursued and showed dysregulation of the classical and alternative complement pathways. We decided to treat CLL which was suspected to be the culprit. At 9 months post-ibrutinib initiation, there was a 90% reduction in the WBC as well as a 94% reduction in proteinuria (17 g/g to 0.97 g/g). This case emphasizes the role of complement dysregulation in the pathogenesis of TMA in CLL patients. Treatment of CLL can restore complement dysregulation and improve renal outcomes.

IgA nephropathy (IgAN) is considered the most common primary glomerulonephritis worldwide with a predilection for Asian-Pacific populations and relative rarity in those of African descent. Perhaps 20%-50% of patients progress to kidney failure. The pathogenesis is incompletely understood. Mesangial deposition of immune complexes containing galactose-deficient IgA1 complexed with anti-glycan IgG or IgA antibodies results in mesangial cell activation and proliferation, inflammatory cell recruitment, complement activation, and podocyte damage. Diagnosis requires a biopsy interpreted by the Oxford criteria. Additional pathologic features include podocytopathy, thrombotic microangiopathy, and C4d staining. Biomarkers predicting adverse outcomes include proteinuria, reduced GFR, hypertension, and pathology. Acceptable surrogate endpoints for therapeutic trials include ongoing proteinuria and rate of eGFR decline. The significance of persisting hematuria remains uncertain. The mainstay of therapy is supportive, consisting of lifestyle modifications, renin-angiotensin inhibition (if hypertensive or proteinuric), sodium-glucose-transporter 2 inhibition (if GFR reduced or proteinuric), and endothelin-receptor antagonism (if proteinuric). Immunosuppression should be considered for those at high risk after maximal supportive care. Corticosteroids are controversial with the most positive results observed in Chinese. They carry a high risk of serious side effects. Similarly, mycophenolate may be most effective in Chinese. Other immunosuppressants are of uncertain benefit. Tonsillectomy appears efficacious in Japanese. Active areas of investigation include B-cell inhibition with agents targeting the survival factors BAFF and APRIL and complement inhibition with agents targeting the alternate pathway (Factors B and D), the lectin pathway (MASP-2), and the common pathway (C3 and C5). Hopefully soon, the who and the how of immunosuppression will be clarified, and kidney failure can be forestalled.

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.

Eculizumab, a recombined humanized monoclonal antibody which possesses high affinity for the complement protein C5, is a therapeutic agent utilized in the treatment of atypical hemolytic uremic syndrome (aHUS) by inhibiting the terminal complement complex C5b-9. In a pediatric patient with aHUS of 14 months, the administration of eculizumab therapy was accompanied by the inclusion of meningococcal vaccine as part of the national immunization program. Notably, no other antibiotics were administered prior to or during the course of eculizumab treatment. Moreover, there were no occurrences of infusion reactions or meningococcal infections observed throughout the course of treatment. Due to the presence of anti-factor H antibodies and insufficient recovery, glucocorticoids and eculizumab were administered at week 0 and week 1, followed by the initiation of mycophenolate mofetil (MMF) at a dosage of 250 mg (approximately 548 mg/m2) per day starting from Day 10. Due to the recovered of complement antibody after 8 doses of eculizumab, the therapeutic interval was extended from once every 3 weeks to once a month since 9th administration. We experienced and successfully treated a rare case of aHUS with eculizumab in a 14-month-old Chinese pediatric patient.

UNASSIGNED: Atypical hemolytic uremic syndrome (aHUS) is a rare form of thrombotic microangiopathy (TMA) caused by complement dysregulation. Ravulizumab is a C5i approved for the treatment of aHUS. This analysis assessed long-term outcomes of ravulizumab in adults and pediatric patients with aHUS.
UNASSIGNED: This analysis reports 2-year data from 2 phase 3, single-arm studies.
UNASSIGNED: One study included C5i-naïve adults (NCT02949128), and the other included 2 cohorts of pediatric patients (C5i-naïve and those who switched to ravulizumab from eculizumab [pediatric switch patients]; NCT03131219).
UNASSIGNED: Patients received intravenous ravulizumab every 4-8 weeks, with the dose depending on body weight.
UNASSIGNED: The primary endpoint in the studies of C5i-naïve patients was complete TMA response, which consisted of platelet count normalization, lactate dehydrogenase normalization, and ≥25% improvement in serum creatinine concentrations from baseline, at 2 consecutive assessments ≥4 weeks apart.
UNASSIGNED: All analyses used descriptive statistics. No formal statistical comparisons were performed.
UNASSIGNED: In total, 86 and 92 patients were included in efficacy and safety analyses, respectively. Complete TMA response rates over 2 years were 61% and 90% in C5i-naïve adults and pediatric patients, respectively. The median increase in estimated glomerular filtration rate from baseline was maintained over 2 years in C5i-naïve adults (35 mL/min/1.73 m2) and pediatric patients (82.5 mL/min/1.73 m2). Most adverse events and serious adverse events occurred during the first 26 weeks. No meningococcal infections were reported. Improvement in the Functional Assessment of Chronic Illness Therapy - Fatigue score achieved by 26 weeks was maintained over 2 years.
UNASSIGNED: Limitations were the small sample of pediatric switch patients and limited availability of genetic data.
UNASSIGNED: Long-term treatment with ravulizumab is well tolerated and associated with improved hematologic and renal parameters and quality of life in adults and pediatric patients with aHUS.
This research tested a drug called ravulizumab for the treatment of atypical hemolytic uremic syndrome (aHUS). aHUS is a rare disease that causes clots in tiny blood vessels. This can damage the kidneys and other organs. We analyzed data from 2 clinical trials in which children and adults with aHUS received ravulizumab through a tube placed in a vein (intravenous line). They received ravulizumab every 4-8 weeks depending on their weight. We found that treating patients for 2 years with ravulizumab was associated with improved blood health, kidney function, and quality of life and was well tolerated. These results support ravulizumab as a long-term treatment for people with aHUS.

Gene therapy has brought tremendous hope for patients with severe life-threatening monogenic diseases. Although studies have shown the efficacy of gene therapy, serious adverse events have also emerged, including thrombotic microangiopathy (TMA) following viral vector-based gene therapy. In this review, we briefly summarize the concept of gene therapy, and the immune response triggered by viral vectors. We also discuss the incidence, presentation, and potential underlying mechanisms, including complement activation, of gene therapy-associated TMA. Further studies are needed to better define the pathogenesis of this severe complication of gene therapy, and the optimal measures to prevent it.