Pulmonary tumor thrombotic microangiopathy: Two case reports and literature review.

RATIONALE: Pulmonary tumor thrombotic microangiopathy (PTTM) is a rare but serious complication in patients with malignancy; its main manifestation includes acute pulmonary hypertension with severe respiratory distress. More than 200 cases have been reported since it was first identified in 1990. PTTM accounts for approximately 0.9% to 3.3% of deaths due to malignancy, but only a minority of patients are diagnosed ante-mortem, with most patients having a definitive diagnosis after autopsy. PATIENT CONCERNS: Two middle-aged women both died within a short period of time due to progressive dyspnea and severe pulmonary hypertension. DIAGNOSES: One patient was definitively confirmed as a gastrointestinal malignant tumor by liver puncture biopsy pathology. Ultimately, the clinical diagnosis was pulmonary tumor thrombotic microangiopathy. INTERVENTIONS: The patient was treated symptomatically with oxygen, diuresis, and anticoagulation, while a liver puncture was perfected to clarify the cause. OUTCOMES: Two cases of middle-aged female patients with rapidly progressive pulmonary hypertension and respiratory failure resulted in death with malignant neoplasm. LESSONS: PTTM has a rapid onset and a high morbidity and mortality rate. Our clinicians need to be more aware of the need for timely diagnosis through a targeted clinical approach, leading to more targeted treatment and a better prognosis.

Thrombotic microangiopathy in patients with sickle cell disease.

OBJECTIVE: To describe two cases of patients who had thrombotic microangiopathy (TMA) associated with sickle cell disease (SCD). CASE DESCRIPTION: Both patients started with a painful crisis and had acute chest syndrome during hospitalization. They showed significant worsening of hemolytic anemia, with very high levels of lactate dehydrogenase, thrombocytopenia, lowered level of consciousness, organ damage and the presence of schistocytes in peripheral blood. Due to the possibility of TMA, despite the very rare association with SCD, they were treated with fresh frozen plasma replacement and plasmapheresis, with good response. COMMENTS: TMA is a serious, life-threatening disease, characterized by microangiopathic hemolytic anemia, thrombocytopenia, and organ damage. The association of SCD and TMA is difficult to diagnose, since they can share a similar clinical presentation. Recognizing this association and promptly instituting treatment may impact the survival of these patients.

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.

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.

Renal manifestations in adult-onset Still's disease: a systematic review.

OBJECTIVE: We aimed to review the literature on the clinical presentation, renal pathology, treatment, and outcome of renal manifestations in adult-onset Still's disease (AOSD). METHODS: We used PRISMA guidelines for our systematic review and included all English-language original articles from inception till September 15, 2023, on AOSD and kidney involvement in any form. Data on patient demographics, diagnostic criteria, clinical presentation, renal pathology, treatment employed including dialysis, outcome, cause of death were collected and analyzed. RESULTS: The median age at the diagnosis of renal issues was 37, with a higher prevalence among females (58.1%). Among the cases, 28 experienced renal problems after being diagnosed with AOSD, 12 had simultaneous diagnoses of renal issues and AOSD, and in 4 cases, renal problems appeared before AOSD diagnosis. Out of the 44 cases, 36 underwent renal biopsy, revealing various pathology findings including AA amyloidosis (25%), collapsing glomerulopathy (11.4%), thrombotic microangiopathy (TMA) (11.4%), IgA nephropathy (9.1%), minimal change disease (6.8%), and others. Some cases were clinically diagnosed with TMA, proximal tubular dysfunction, or macrophage activation syndrome-related acute kidney injury. Treatment approaches varied, but glucocorticoids were commonly used. Renal involvement was associated with increased mortality and morbidity, with 6 out of 44 patients passing away, 4 progressing to end-stage renal disease (ESRD), and data on 2 cases' outcomes not available. CONCLUSION: Renal manifestations in AOSD are diverse but rarely studied owing to the rarity of the disease. Studies with larger data would be essential to study further on the pathogenesis and implications.

Endoscopic manifestation of intestinal transplant-associated microangiopathy after stem cell transplantation.

BACKGROUND: Endoscopic features of intestinal transplant-associated microangiopathy (iTAM) have not been comprehensively investigated. This study aimed to examine the endoscopic characteristics of patients diagnosed with iTAM. METHODS: This retrospective analysis included 14 patients pathologically diagnosed with iTAM after stem cell transplantation for hematolymphoid neoplasms (n = 13) or thalassemia (n = 1). The sex, age at diagnosis, endoscopic features, and prognosis of each patient were assessed. Serological markers for diagnosing transplant-associated thrombotic microangiopathy were also evaluated. RESULTS: The mean age at the time of iTAM diagnosis was 40.2 years. Patients diagnosed based on the pathognomonic pathological changes of iTAM presented with diverse symptoms at the times of endoscopic examinations, including diarrhea (n = 10), abdominal pain (n = 5), nausea (n = 4), appetite loss (n = 2), bloody stools (n = 2), abdominal discomfort (n = 1), and vomiting (n = 1). At the final follow-up, six patients survived, while eight patients succumbed, with a median time of 100.5 days (range: 52-247) post-diagnosis. Endoscopic manifestations included erythematous mucosa (n = 14), erosions (n = 13), ulcers (n = 9), mucosal edema (n = 9), granular mucosa (n = 9), and villous atrophy (n = 4). Erosions and/or ulcers were primarily observed in the colon (10/14, 71%), followed by the ileum (9/13, 69%), stomach (4/10, 40%), cecum (5/14, 36%), duodenum (3/10, 30%), rectum (4/14, 29%), and esophagus (1/10, 10%). Cytomegalovirus infection (n = 4) and graft-versus-host disease (n = 2) coexisted within the gastrointestinal tract. Patients had de novo prolonged or progressive thrombocytopenia (6/14, 43%), decreased hemoglobin concentration (4/14, 29%), reduced serum haptoglobin level (3/14, 21%), and a sudden and persistent increase in lactate dehydrogenase level (2/14, 14%). Peripheral blood samples from 12 patients were evaluated for schistocytes, with none exceeding 4%. CONCLUSIONS: This study provides a comprehensive exploration of the endoscopic characteristics of iTAM. Notably, all patients exhibited erythematous mucosa throughout the gastrointestinal tract, accompanied by prevalent manifestations, such as erosions (93%), ulcers (64%), mucosal edema (64%), granular mucosa (64%), and villous atrophy (29%). Because of the low positivity for serological markers of transplant-associated thrombotic microangiopathy in patients with iTAM, endoscopic evaluation and biopsy of these lesions are crucial, even in the absence of these serological features.

Cancer-related thrombotic microangiopathy and disseminated intravascular coagulation in a patient with bone marrow carcinomatosis of unknown primary origin: A case report.

BACKGROUND: Cancer-related thrombotic microangiopathy (CR-TMA) is a rare type of Coombs-negative hemolytic anemia, which is caused by malignancy and has a poor prognosis. CASE: A 76-year-old female was referred to our hospital due to Coombs-negative hemolytic anemia, which was causing fatigue and dyspnea on exertion, accompanied by schistocytosis. A bone marrow examination demonstrated bone marrow carcinomatosis, and the tumor cells were morphologically suspected to be signet-ring cell carcinoma cells. As we failed to find the primary tumor site before the patient died, she was diagnosed with CR-TMA due to bone marrow carcinomatosis of unknown primary origin. Thrombotic thrombocytopenic purpura (TTP) was rapidly ruled out based on her PLASMIC score. In addition, immunohistochemical staining of a clot section of the bone marrow and tumor marker data were useful for narrowing down the likely primary tumor site. CONCLUSION: Although CR-TMA is an extremely rare phenomenon, clinicians who suspect CR-TMA should quickly rule out TTP and decide whether to provide appropriate chemotherapy or plan for palliative care.

Neurologic Complications of the Central Nervous System after Allogeneic Stem Cell Transplantation: The Role of Transplantation-Associated Thrombotic Microangiopathy as a Potential Underreported Cause.

Neurologic complications (NCs), especially those of the central nervous system (CNS), represent a severe complication after allogeneic stem cell transplantation (allo-HSCT) and are associated with relevant morbidity and mortality. We aimed to characterize the potential risk factors for the development of CNS-NC, with a special focus on the role of calcineurin inhibitors (CNIs) as a predisposing factor. For this purpose, we compared cyclosporin A (CsA) versus tacrolimus (TAC) with respect to their influence on the incidence and type of CNS-NC after allo-HSCT. We retrospectively analyzed the incidence, risk factors, and impact on outcomes of CNS-NC diagnosed during the post-transplantation follow-up in patients with different high-risk hematologic malignancies who underwent allo-HSCT at our institution over a 20-year period. All patients included in the analysis received CNI (CsA or TAC) as graft-versus-host disease (GVHD) prophylaxis. We evaluated a total of 739 consecutive patients who underwent transplantation between December 1999 and April 2019. During a median follow-up of 6.8 years, we observed a CNS-NC incidence of 17%. The development of CNS-NC was associated with decreased overall survival (OS) and increased transplantation-related mortality (TRM). The most frequent CNS-NCs were infections (30%) and neurologic adverse events related to the administration of CNI, TAC, or CsA as GVHD prophylaxis (42%). In the multivariable analysis, age, total body irradiation (TBI), and severe acute GVHD and chronic GVHD were significant risk factors in the development of CNS-NCs. TAC compared with CsA emerged as an independent predisposing factor for CNS-NCs. The TAC-associated risk of CNS-NCs was related mostly to the occurrence of transplantation-associated thrombotic microangiopathy (TA-TMA) with neurologic manifestations (neuro-TA-TMA), although the general TA-TMA incidence was comparable in the 2 CNI subgroups. CNS-NCs are associated with poor prognosis after allo-HSCT, with TAC emerging as a potential yet insufficiently characterized predisposing factor.

Use of Eculizumab in Pediatric Patients with High-Risk Transplantation-Associated Thrombotic Microangiopathy: Outcomes and Risk Factors Associated with Response and Survival. A Retrospective Study on Behalf of the Spanish Group for Hematopoietic Transplantation and Cellular Therapy (GETH-TC).

Transplantation-associated thrombotic microangiopathy (TA-TMA) is associated with high morbidity and mortality. Although survival has improved significantly with the introduction of eculizumab, the need for improvement remains, especially in high-risk patients. This study aimed to describe the results obtained with eculizumab in a pediatric cohort with the attempt to define which risk factors could determine the response to treatment. We designed a national multicenter retrospective study of children treated with eculizumab for high-risk TA-TMA. The study cohort comprised 29 patients who had undergone a first (n = 28) or second (n = 1) allogeneic hematopoietic stem cell transplantation (HSCT) for malignant (n = 17) or nonmalignant (n = 12) disease. The median time from HSCT to TA-TMA diagnosis was 154 days (interquartile range [IQR], 103 to 263 days). Eleven patients (38%) who were initially diagnosed with low- to intermediate-risk TA-TMA progressed to high-risk TA-TMA (hrTA-TMA), within a median time of 4 days (IQR, 1 to 33 days). SC5b-9 was increased in 90% of 20 patients in whom it was measured. Renal (n = 12), pulmonary (n = 1), and intestinal (n = 1) biopsy confirmed the diagnosis in 12 of 14 patients (85%). Seventeen patients (58%) had extrarenal involvement with serositis (n = 13; 44,8%), pulmonary (n = 12; 41,4%), gastrointestinal (n = 8; 27.6%), cardiovascular (n = 7; 24.1%), or central nervous system (CNS) (n = 2; 6.9%) involvement. The median time from hrTA-TMA diagnosis to the initiation of eculizumab was 7 days (IQR, 1 to 8 days). Overall, 19 patients (65.5%) responded to eculizumab, of whom 17 (58.6%) achieved a complete response and 2 (6.9%) achieved a partial response. The remaining 10 patients (34.5%) did not show any of response. The overall response rate to eculizumab for TA-TMA was 27.59% (95% confidence interval [CI], 14.87% to 47.66%) at 1 month, 55.17% (95% CI, 38.43% to 73.48%) at 3 months, and 62.07% (95% CI, 45.10% to 79.13%) at 6 months after eculizumab initiation. In multivariate analysis, the pulmonary involvement decreased the probability of response (hazard ratio [HR], .18; P = .0298). The 1-year overall survival (OS) was 55.2% (95% CI, 35.6% to 71.0%) for the whole cohort and 83.3% (95% CI, 56.7% to 94.3%) for patients who responded to eculizumab. Pulmonary involvement (HR, 14.93; P = .0043) and CNS involvement (HR, 8.63; P = .0497) were associated with a statistically significant decrease in survival. We found that patients diagnosed with hrTA-TMA with pulmonary involvement had a poor response to eculizumab, and that patients with pulmonary and CNS involvement had significantly decreased survival. Given these results, we hypothesize that providing eculizumab therapy at an early stage of the disease before organ damage is established might significantly improve the response and, consequently, survival.

An unusual complication of kidney biopsy: a case report.

BACKGROUND: The kidney biopsy is a routine procedure. Once an indication has been established, the benefit-risk balance may be considered. Sometimes, even with effective treatment, a severe complication may develop. CASE PRESENTATION: We present the case of a Caucasian 20-year-old young woman admitted to investigating and treating acute kidney injury. Renal involvement was characterized by kidney damage requiring hemodialysis treatment, positive immunologic testing, 0.5 g/day proteinuria, and microscopic hematuria. Contraindications were excluded, so an ultrasound-guided kidney biopsy was performed. To reduce the bleeding complication, Octostim (desmopressin) was administered. There were no direct complications following the kidney biopsy, so we continued the immunosuppressive treatment. Histologically founded thrombotic microangiopathy. However, 1 week later, severe bleeding developed with the need for urgent surgical left kidney removal. CONCLUSION: Kidney biopsy can be considered a routine procedure, and various bleeding episodes are most common in terms of complications, the detection of which is essential. Delayed bleeding complications are rare and can be caused by minor injuries. Our young patient had no injury during the hospitalization. We hypothesized that the developed serious and delayed bleeding complication resulted from effective immunosuppressive treatment. To the best of our knowledge, this is the first such case to date. However, renal biopsy in the case of thrombotic microangiopathy requires caution.

A case-based narrative review of pregnancy-associated atypical hemolytic uremic syndrome/complement-mediated thrombotic microangiopathy.

Atypical hemolytic uremic syndrome is a complement-mediated thrombotic microangiopathy caused by uncontrolled activation of the alternative complement pathway in the setting of autoantibodies to or rare pathogenic genetic variants in complement proteins. Pregnancy may serve as a trigger and unmask atypical hemolytic uremic syndrome/complement-mediated thrombotic microangiopathy (aHUS/CM-TMA), which has severe, life-threatening consequences. It can be difficult to diagnose aHUS/CM-TMA in pregnancy due to overlapping clinical features with other thrombotic microangiopathy syndromes including hypertensive disorders of pregnancy. However, the distinction among thrombotic microangiopathy etiologies in pregnancy is important because each syndrome has specific disease management and treatment. In this narrative review, we discuss 2 cases to illustrate the diagnostic challenges and evolving approach in the management of pregnancy-associated aHUS/CM-TMA. The first case involves a 30-year-old woman presenting in the first trimester who was diagnosed with aHUS/CM-TMA and treated with eculizumab from 19 weeks' gestation. Genetic testing revealed a likely pathogenic variant in CFI. She successfully delivered a healthy infant at 30 weeks' gestation. In the second case, a 22-year-old woman developed severe postpartum HELLP syndrome, requiring hemodialysis. Her condition improved with supportive management, yet investigations assessing for aHUS/CM-TMA remained abnormal 6 months postpartum consistent with persistent complement activation but negative genetic testing. Through detailed case discussion describing tests assessing for placental health, fetal anatomy, complement activation, autoantibodies to complement regulatory proteins, and genetic testing for aHUS/CM-TMA, we describe how these results aided in the clinical diagnosis of pregnancy-associated aHUS/CM-TMA and assisted in guiding patient management, including the use of anticomplement therapy.

Investigation of Clinical Features and Association between Vascular Endothelial Injury Markers and Cytomegalovirus Infection Associated with Thrombotic Microangiopathy in Patients with Anti-Neutrophil Cytoplasmic Antibody (ANCA)-Associated Vasculitis: Case-Based Research.

Anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) can occasionally trigger thrombotic microangiopathy (TMA). Cytomegalovirus (CMV) may be reactivated during intensive immunosuppressive therapy for AAV and cause TMA. Therefore, we aimed to evaluate the clinical features of and the association between vascular endothelial injury markers and TMA due to CMV in patients with AAV. A 61-year-old female was diagnosed with AAV and severe kidney injury. Immunosuppressive therapy gradually improved her symptoms and laboratory findings. However, 2 weeks after induction therapy initiation, she exhibited altered consciousness, a significant decrease in platelet count, and hemolytic anemia, resulting in a TMA diagnosis. Plasma exchange did not improve TMA findings and routine screening test revealed CMV infection. Ganciclovir injection improved the infection and TMA findings. Consequently, we diagnosed her with CMV-induced TMA. Both AAV and CMV may induce severe vascular endothelial injury, potentially leading to TMA development. CMV-induced TMA should be considered when TMA develops during induction therapy against AAV. Moreover, of the three serum markers of vascular injury-serum sulfatides, soluble thrombomodulin, and pentraxin 3-serum sulfatides may be associated with the development of TMA, and a high level of soluble thrombomodulin may be associated with the development of CMV viremia during the clinical course of AAV.

Late transplant-associated thrombotic microangiopathy verified in bone marrow biopsy specimens is associated with chronic GVHD and viral infections.

OBJECTIVES: To describe late transplant-associated thrombotic microangiopathy (TA-TMA) as chronic endothelial complication in bone marrow (BM) after allogeneic hematopoietic stem cell transplantation (HSCT). METHODS: BM specimens along with conventional diagnostic parameters were assessed in 14 single-institutional patients with late TA-TMA (more than 100 days after HCST), including 11 late with history of early TA-TMA, 10 with early TA-TMA (within 100 days), and 12 non TA-TMA patients. Three non-HSCT patients served as control. The time points of BM biopsy were +1086, +798, +396, and +363 days after HSCT, respectively. RESULTS: Late TA-TMA patients showed an increase of CD34+ and von Willebrand Factor (VWF)+ microvascular endothelial cells with atypical VWF+ conglomerates forming thickened VWF+ plaque sinus in the BM compared to patients without late TA-TMA and non-HSCT. Severe chronic (p = .002), steroid-refractory GVHD (p = .007) and reactivation of HHV6 (p = .002), EBV (p = .003), and adenovirus (p = .005) were pronounced in late TA-TMA. Overall and relapse-free survival were shorter in late TA-TMA than in patients without late TA-TMA (5-year OS and RFS: 78.6% vs. 90.2%, 71.4% vs. 86.4%, respectively). CONCLUSION: Chronic allo-immune microangiopathy in BM associated with chronic, steroid-refractory GVHD and/or viral infections are key findings of late, high-risk TA-TMA, which deserves clinical attention.

D-dimer and sinusoidal obstructive syndrome-novel poor prognostic features of thrombotic microangiopathy in children after hematopoietic cellular therapy in a single institution prospective cohort study.

Transplant-associated thrombotic microangiopathy (TA-TMA) is a common, severe complication of allogeneic hematopoietic cellular therapy (HCT). Even when treated in many studies, morbidity and mortality rates are high. This prospective single-institution cohort study serially enrolled all allogeneic HCT recipients from August 2019-August 2022. Patients were universally screened for TA-TMA and intermediate and high-risk patients were immediately treated with eculizumab. Sub-distribution cox-proportional hazards models were used to identify sub-distribution hazard ratios (sHR)  for multi-organ dysfunction (MOD) and non-relapse-related mortality (NRM). Of 136 patients, 36 (26%) were diagnosed with TA-TMA and 21/36 (58%) developed MOD, significantly more than those without TA-TMA, (p < .0001). Of those with TA-TMA, 18 (50%) had high-risk TA-TMA (HR-TA-TMA), 11 (31%) had intermediate-risk TA-TMA (IR-TA-TMA), and 8 (22%) had standard risk (SR-TA-TMA). Twenty-six were treated with eculizumab (1/8 SR, 7/11 IR, and 18/18 HR). Elevated D-dimer predicted the development of MOD (sHR 7.6, 95% confidence interval [CI] 1.8-32.3). Children with concurrent sinusoidal obstructive syndrome (SOS) and TA-TMA had an excess risk of MOD of 34% and data supported a biologic interaction. The adjusted NRM risk was significantly higher in the TA-TMA patients (sHR 10.54, 95% CI 3.8-29.2, p < .0001), despite prompt treatment with eculizumab. Significant RF for NRM in TA-TMA patients included SOS (HR 2.89, 95% 1.07-7.80) and elevated D-dimer (HR 3.82, 95% CI 1.14-12.84). An unrelated donor source and random urine protein to creatine ratio ≥2 mg/mg were significantly associated with no response to eculizumab (odds ratio 15, 95% CI 2.0-113.6 and OR 6.5, 95% CI 1.1-38.6 respectively). TA-TMA was independently associated with NRM despite early diagnosis and treatment with eculizumab in this large pediatric transplant cohort. Prognostic implications of D-dimer in TA-TMA merit further investigation as this is a readily accessible biomarker. Concurrent SOS is an exclusion criterion of many ongoing clinical trials, but these data highlight these patients could benefit from novel therapeutic approaches. Multi-institutional clinical trials are needed to understand the impact of TA-TMA-targeted therapies.

Clinical Evaluation and Management of Thrombotic Microangiopathy.

Thrombotic microangiopathy (TMA) refers to a diverse group of diseases that share clinical and histopathologic features. TMA is clinically characterized by microangiopathic hemolytic anemia, consumptive thrombocytopenia, and organ injury that stems from endothelial damage and vascular occlusion. There are several disease states with distinct pathophysiological mechanisms that manifest as TMA. These conditions are associated with significant morbidity and mortality and require urgent recognition and treatment. Thrombotic thrombocytopenic purpura and hemolytic uremic syndrome are traditionally considered to be primary forms of TMA, but TMA more commonly occurs in association with a coexisting condition such as infection, pregnancy, autoimmune disease, or malignant hypertension, among others. Determining the cause of TMA is a diagnostic challenge because of limited availability of disease-specific testing. However, identifying the underlying etiology is imperative as treatment strategies differ. Our understanding of the conditions that cause TMA is evolving. Recent advances have led to improved comprehension of the varying pathogenic mechanisms that drive TMA. Development of targeted therapeutics has resulted in significant improvements in patient outcomes. In this article, we review the pathogenesis and clinical features of the different TMA-causing conditions. We outline a practical approach to diagnosis and management and discuss empiric and disease-specific treatment strategies.

Complement-mediated thrombotic microangiopathy treated with anticomplement protein 5 therapy, a retrospective study.

BACKGROUND: Complement-mediated thrombotic microangiopathy (CM-TMA), also called atypical hemolytic uremic syndrome (aHUS), is a difficult-to-diagnose rare disease that carries severe morbidity and mortality. Anti-C5 monoclonal antibodies (aC5-mab) are standard treatments, but large studies and long-term data are scarce. Here, we report our single institution experience to augment the knowledge of CM-TMA treated with aC5-mab therapy. METHODS: We aimed to assess the short and long-term effects of aC5-mab in patients diagnosed with CM-TMA treated outside of a clinical trial. This was a retrospective study. We included all patients diagnosed with CM-TMA and treated with aC5-mab at our institution. There were no exclusion criteria. Endpoints included complete TMA response (CR) defined as normalization of hematological parameters and ≥25% improvement in serum creatinine (Cr) from baseline in patients with renal disease, relapse defined as losing the previously achieved CR, morbidity, adverse events, and survival. RESULTS: We found 28 patients with CM-TMA treated with aC5-mab. The median age was 50 years. Baseline laboratories: platelet counts 93 × 109 /L, hemoglobin 8.6 g/dL, lactate dehydrogenase 1326 U/L, serum Cr 4.7 mg/dL, and estimated glomerular filtration rate 19 mL/min. One individual was on renal replacement therapy (RRT) and 10 initiated RRT within 5 days of the first dose of aC5-mab. Genetic variants associated with CM-TMA included mutations in C3, CFB, CFH, CFHR1/3, CFI, and MCP. The mean duration of hospitalization was 24 days. The median time to initiation of aC5-mab was 10 days. Sixteen subjects received RRT. At the time of hospital discharge, 27 were alive, 14 remained on RRT, and 4 had a CR. At 6 months, 23 patients were alive, 18 continued aC5-mab, 8 remained on RRT, and 9 had a CR. At the last follow-up visit past 6 months, 20 were alive, 14 continued aC5-mab, 5 remained on RRT, 12 had a CR, and 1 was lost to follow-up. CONCLUSIONS: Our study provides real-world experience and insight into the long-term outcomes of CM-TMA treated with aC5-mab. Our findings validate that CM-TMA is an aggressive disease with significant morbidity and mortality, and confirm that aC5-mab is a relatively effective therapy for CM-TMA. Our study adds practical, real-world experience to the literature, but future research remains imperative.