A prospective multi-institutional study of eculizumab to treat high-risk stem cell transplantation-associated TMA.

ABSTRACT: High-risk, complement mediated, untreated transplant-associated thrombotic microangiopathy (hrTMA) has dismal outcomes due to multi-organ dysfunction syndrome (MODS). The complement C5 blocker eculizumab shows promising results in hrTMA, but has not been prospectively studied in hematopoietic stem cell transplant (HCT) recipients. We performed the first multi-institutional prospective study in children and young adults to evaluate eculizumab as an early targeted intervention for hrTMA/MODS. We hypothesized that eculizumab would more than double survival in HCT recipients with hrTMA, compared to our prior study of prospectively screened, untreated hrTMAs serving as historical controls. HrTMA features (elevated terminal complement (sC5b-9) and proteinuria measured by random urine protein/creatinine ratio (≥1mg/mg)) were required for inclusion. The primary endpoint was survival at 6 six-months from hrTMA diagnosis. Secondary endpoints were cumulative incidence of MODS 6 months after hrTMA diagnosis and 1-year posttransplant survival. Eculizumab dosing included intensive loading, induction, and maintenance phases for up to 24 weeks of therapy. All 21 evaluated study subjects had MODS. Primary and secondary study endpoints were met by demonstrating survival of 71% (P < .0001) 6 months after hrTMA diagnosis and 62% 1 year after transplant. Of fifteen survivors, 11 (73%) fully recovered organ function and are well. Our study demonstrates significant improvement in survival and recovery of organ function in hrTMA using an intensified eculizumab dosing and real time biomarker monitoring. This study serves as a benchmark for planning future studies that should focus on preventative measures or targeted therapy to be initiated prior to organ injury. This trial was registered at www.clinicaltrials.gov as #NCT03518203.

Emicizumab prophylaxis in infants with hemophilia A (HAVEN 7): primary analysis of a phase 3b open-label trial.

ABSTRACT: Subcutaneous emicizumab enables prophylaxis for people with hemophilia A (HA) from birth, potentially reducing risk of bleeding and intracranial hemorrhage (ICH). HAVEN 7 (NCT04431726) is the first clinical trial of emicizumab dedicated to infants, designed to investigate the efficacy, safety, pharmacokinetics, and pharmacodynamics of emicizumab in those aged ≤12 months with severe HA without factor VIII (FVIII) inhibitors. Participants in this phase 3b trial received emicizumab 3 mg/kg maintenance dose every 2 weeks for 52 weeks and are continuing emicizumab during the 7-year long-term follow-up. Efficacy end points included annualized bleed rate (ABR): treated, all, treated spontaneous, and treated joint bleeds. Safety end points included adverse events (AEs), thromboembolic events (TEs), thrombotic microangiopathies (TMAs), and immunogenicity (anti-emicizumab antibodies [ADAs] and FVIII inhibitors). At primary analysis, 55 male participants had received emicizumab (median treatment duration: 100.3; range, 52-118 weeks). Median age at informed consent was 4.0 months (range, 9 days to 11 months 30 days). Model-based ABR for treated bleeds was 0.4 (95% confidence interval, 0.30-0.63), with 54.5% of participants (n = 30) having zero treated bleeds. No ICH occurred. All 42 treated bleeds in 25 participants (45.5%) were traumatic. Nine participants (16.4%) had ≥1 emicizumab-related AE (all grade 1 injection-site reactions). No AE led to treatment changes. No deaths, TEs, or TMAs occurred. No participant tested positive for ADAs. Two participants were confirmed positive for FVIII inhibitors. This primary analysis of HAVEN 7 indicates that emicizumab is efficacious and well tolerated in infants with severe HA without FVIII inhibitors.

Microlyse: a thrombolytic agent that targets VWF for clearance of microvascular thrombosis.

Thrombotic microangiopathies are hallmarked by attacks of disseminated microvascular thrombosis. In thrombotic thrombocytopenic purpura (TTP), this is caused by a rise in thrombogenic ultra-large von Willebrand factor (VWF) multimers because of ADAMTS13 deficiency. We previously reported that systemic plasminogen activation is therapeutic in a TTP mouse model. In contrast to its natural activators (ie, tissue plasminogen activator and urokinase plasminogen activator [uPA]), plasminogen can directly bind to VWF. For optimal efficacy and safety, we aimed to focus and accelerate plasminogen activation at sites of microvascular occlusion. We here describe the development and characterization of Microlyse, a fusion protein consisting of a high-affinity VHH targeting the CT/CK domain of VWF and the protease domain of uPA, for localized plasminogen activation on microthrombi. Microlyse triggers targeted destruction of platelet-VWF complexes by plasmin on activated endothelial cells and in agglutination studies. At equal molar concentrations, Microlyse degrades microthrombi sevenfold more rapidly than blockade of platelet-VWF interactions with a bivalent humanized VHH (caplacizumab*). Finally, Microlyse attenuates thrombocytopenia and tissue damage (reflected by increased plasma lactate dehydrogenase activity, as well as PAI-1 and fibrinogen levels) more efficiently than caplacizumab* in an ADAMTS13-/- mouse model of TTP, without affecting hemostasis in a tail-clip bleeding model. These findings show that targeted thrombolysis of VWF by Microlyse is an effective strategy for the treatment of TTP and might hold value for other forms of VWF-driven thrombotic disease.

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.

Eculizumab as Salvage Treatment for Thrombotic Microangiopathy After Lung Transplantation.

BACKGROUND: Thrombotic microangiopathy (TMA) is a rare complication after lung transplantation (LT) that has seldom been characterized in detail. Recent evidence has linked TMA other than primary atypical hemolytic uremic syndrome (aHUS) with hyperactivation of the complement alternative pathway. The focus of this investigation was to analyze the treatment response with eculizumab in TMA after LT. METHODS: Case series where we have studied 11 patients with TMA after LT from 2 Spanish tertiary healthcare centers. Clinical data and response rates to eculizumab are provided. RESULTS: The main indication for lung transplant was chronic obstructive pulmonary disease (COPD) (36%) and most cases (82%) received bilateral LT. The median time to TMA diagnosis was 11.6 months (4.7-28.9) and the TMA trigger in the majority of cases (73%) was immunosuppressive drugs. Platelet and hemoglobin nadir were 58 × 103/µL (24-108) and 7.7 g/dL (7.1-7.9), respectively. All cases presented acute kidney injury (AKI) with a median creatinine of 4 mg/dL (3.2-4.8) and 54.5% required acute dialysis. Eculizumab was started after a median time of 8 days (6-14) with a median duration of 3 weeks (2-8). Complete TMA response was observed in 7 (63.6%) cases and hematologic response in 10 (90.9%). The time to hematologic and renal response was 23 days (13-29) and 28 days (14-46), respectively. CONCLUSIONS: TMA after LT is infrequent but potentially devastating. Our findings suggest that short cycles of eculizumab may be effective for severe TMA after LT.

MASP2 inhibition by narsoplimab suppresses endotheliopathies characteristic of transplant-associated thrombotic microangiopathy: in vitro and ex vivo evidence.

Transplant-associated thrombotic microangiopathy (TA-TMA) is an endotheliopathy complicating up to 30% of allogeneic hematopoietic stem cell transplants (alloHSCT). Positive feedback loops among complement, pro-inflammatory, pro-apoptotic, and coagulation cascade likely assume dominant roles at different disease stages. We hypothesized that mannose-binding lectin-associated serine protease 2 (MASP2), principal activator of the lectin complement system, is involved in the microvascular endothelial cell (MVEC) injury characteristic of TA-TMA through pathways that are susceptible to suppression by anti-MASP2 monoclonal antibody narsoplimab. Pre-treatment plasmas from 8 of 9 TA-TMA patients achieving a complete TMA response in a narsoplimab clinical trial activated caspase 8, the initial step in apoptotic injury, in human MVEC. This was reduced to control levels following narsoplimab treatment in 7 of the 8 subjects. Plasmas from 8 individuals in an observational TA-TMA study, but not 8 alloHSCT subjects without TMA, similarly activated caspase 8, which was blocked in vitro by narsoplimab. mRNA sequencing of MVEC exposed to TA-TMA or control plasmas with and without narsoplimab suggested potential mechanisms of action. The top 40 narsoplimab-affected transcripts included upregulation of SerpinB2, which blocks apoptosis by inactivating procaspase 3; CHAC1, which inhibits apoptosis in association with mitigation of oxidative stress responses; and pro-angiogenesis proteins TM4SF18, ASPM, and ESM1. Narsoplimab also suppressed transcripts encoding pro-apoptotic and pro-inflammatory proteins ZNF521, IL1R1, Fibulin-5, aggrecan, SLC14A1, and LOX1, and TMEM204, which disrupts vascular integrity. Our data suggest benefits to narsoplimab use in high-risk TA-TMA and provide a potential mechanistic basis for the clinical efficacy of narsoplimab in this disorder.

The treatment of atypical hemolytic uremic syndrome with eculizumab in pediatric patients: a systematic review.

BACKGROUND: The atypical hemolytic uremic syndrome (aHUS) is a rare form of thrombotic microangiopathy associated with high morbidity and high mortality. Eculizumab, a humanized anti-C5 monoclonal antibody, was the first medication approved for treating aHUS in 2011. OBJECTIVE: The objective of this study is to evaluate the efficacy and safety of eculizumab treatment in pediatric patients with aHUS. DATA SOURCES: We consulted PubMed, Scopus, SciELO, and Cochrane Library databases in July 2021. The descriptors were as follows: "Atypical Hemolytic Uremic Syndrome," "aHUS," "eculizumab," "Pediatrics," "Pediatric," "Child," "Children," "Adolescent." STUDY ELIGIBILITY CRITERIA: The study eligibility criteria are as follows: clinical trials and observational studies that included pediatric patients with aHUS diagnosis and who were treated with eculizumab. PARTICIPANTS AND INTERVENTIONS: The participants are pediatric patients, up to 18 years old, with aHUS. The intervention was eculizumab treatment. STUDY APPRAISAL: For quality assessment, we used the Newcastle-Ottawa Scale, the National Institutes of Health (NIH) quality assessment tool for case series studies, and the Risk of Bias In Non-Randomized Studies of Interventions (ROBINS-I) tool. RESULTS: The initial search retrieved 433 studies, from which 15 were selected after complete assessment: 9 cohorts, 4 case series, and 1 clinical trial. The publication date ranged from 2015 to 2021. In total, 940 pediatric patients were included, and 682 received eculizumab. All studies reported improvements in renal and hematological parameters in most of the patients treated with eculizumab. The mortality rate was 1.6% for all patients treated with eculizumab. LIMITATIONS: The number of studies is limited, and the included studies were methodologically heterogeneous. The studies were mostly observational and many had small sample sizes. CONCLUSIONS: Eculizumab appears to be safe and effective for the treatment of aHUS in pediatric patients. More research is necessary to establish long-term efficacy, safety, and time of discontinuation. SYSTEMATIC REVIEW REGISTRATION NUMBER: CRD42021266255.

COVID-19 associated thrombotic microangiopathy.

A limited number of cases of thrombotic microangiopathy (TMA) have previously been reported in association with COVID-19. Our report describes two cases of TMA associated with COVID-19, one of which was successfully treated with eculizumab. The first case was a 23-month-old girl, and the second case was a 9-month-old boy. PCR tests for SARS-CoV-2 were positive in both cases, and laboratory results showed microangiopathic haemolytic anaemia, thrombocytopenia, and acute kidney injury. No known aetiology for TMA was found in either case. Stool tests for Shigatoxin-producing Escherichia coli were negative. Coagulation tests, ADAMTS13 activity, serum complement levels, and homocysteine levels were all within the normal range. No known genetic mutation was found, including mutations of complement, diacylglycerol kinase epsilon, and cobalamin C. In the first case, eculizumab was administered due to persistent haemolysis and prolonged anuria. In conclusion, TMA may be associated with COVID-19 infection. Treatment with eculizumab may be beneficial in selected patients because of the potential activation of the complement system.

Complement blockade for TA-TMA: lessons learned from a large pediatric cohort treated with eculizumab.

Overactivated complement is a high-risk feature in hematopoietic stem cell transplant (HSCT) recipients with transplant-associated thrombotic microangiopathy (TA-TMA), and untreated patients have dismal outcomes. We present our experience with 64 pediatric HSCT recipients who had high-risk TA-TMA (hrTA-TMA) and multiorgan injury treated with the complement blocker eculizumab. We demonstrate significant improvement to 66% in 1-year post-HSCT survival in treated patients from our previously reported untreated cohort with same hrTA-TMA features that had 1-year post-HSCT survival of 16.7%. Responding patients benefited from a brief but intensive course of eculizumab using pharmacokinetic/pharmacodynamic-guided dosing, requiring a median of 11 doses of eculizumab (interquartile range [IQR] 7-20). Treatment was discontinued because TA-TMA resolved at a median of 66 days (IQR 41-110). Subjects with higher complement activation measured by elevated blood sC5b-9 at the start of treatment were less likely to respond (odds ratio, 0.15; P = .0014) and required more doses of eculizumab (r = 0.43; P = .0004). Patients with intestinal bleeding had the fastest eculizumab clearance, required the highest number of eculizumab doses (20 vs 9; P = .0015), and had lower 1-year survival (44% vs 78%; P = .01). Over 70% of survivors had proteinuria on long-term follow-up. The best glomerular filtration rate (GFR) recovery in survivors was a median 20% lower (IQR, 7.3%-40.3%) than their pre-HSCT GFR. In summary, complement blockade with eculizumab is an effective therapeutic strategy for hrTA-TMA, but some patients with severe disease lacked a complete response, prompting us to propose early intervention and search for additional targetable endothelial injury pathways.

Microangiopathy associated with gemcitabine: a drug interaction with nab-paclitaxel? A case series and literature review.

PURPOSE: Gemcitabine and nab-paclitaxel association can be used in first- or second-line treatment for metastatic pancreatic adenocarcinoma. Here, we report five cases of supposed gemcitabine-induced thrombotic microangiopathy (G-TMA), four of them with nab-paclitaxel. We assumed that nab-paclitaxel could be responsible for a potential drug interaction with gemcitabine, increasing the risk of thrombotic microangiopathy occurrence. METHODS: Clinicians reported cases of supposed G-TMA that were declared to the Pharmacovigilance center. We collected the patients' data (clinical and biological characteristics), calculated an incidence rate of G-TMA in our center, and a Naranjo score for each patient. We also reviewed literature on a potential drug interaction between nab-paclitaxel and gemcitabine. RESULTS: Four patients were treated with nab-paclitaxel/gemcitabine and one with gemcitabine alone. The time onset of supposed G-TMA was 2 to 11 months. Patients developed anemia, thrombocytopenia, and renal failure. The incidence rate of supposed G-TMA was 2.7% in our center compared to 0.31% (Meyler's Side Effect of Drugs) and 0.01% in the gemcitabine's summary of product characteristics. Literature review outlined an increase of gemcitabine's plasmatic concentrations induced by nab-paclitaxel (Drugs® website) and a potentiation of gemcitabine's effect by nab-paclitaxel in murine models. This study showed that nab-paclitaxel inhibits cytidine deaminase's activity (responsible for gemcitabine's metabolism) and increases gemcitabine's active metabolite concentrations (gemcitabine triphosphate) in tumor tissues. CONCLUSION: High incidence rate of G-TMA was observed in our cohort due to a potential drug interaction between nab-paclitaxel and gemcitabine with an increased risk of developing G-TMA. Additional pharmacological and pharmaco-epidemiological investigations are mandatory to explore this hypothesis.

Diagnostic Considerations in H1N1 Influenza-induced Thrombotic Microangiopathy.

Influenza virus can trigger atypical hemolytic uremic syndrome and present with complement-driven thrombotic microangiopathy (TMA). When administered promptly, complement-blocking therapies can spare organ injury and be lifesaving. However, diagnosing TMA in the setting of a severe viral infection can be challenging, as a significant overlap of symptoms and disease complications exists. This is particularly true in influenza virus infections and more recently, Coronavirus disease 2019 (COVID-19) infections. We present a 16-year-old male with H1N1 influenza-induced atypical hemolytic uremic syndrome who quickly improved with complement-blocking therapy, highlighting an urgent need to include TMA in the differential diagnosis of severe viral infections.

TAFRO syndrome with renal biopsy successfully treated with steroids and cyclosporine: a case report.

BACKGROUND: TAFRO syndrome is an acute or subacute systemic inflammatory disease with no apparent cause, presenting with fever, generalized edema, thrombocytopenia, renal damage, anemia, and organ enlargement. Interleukin-6, vascular endothelial growth factor, and other cytokines are thought to be the etiologic agents that increase vascular permeability and cause the resulting organ damage. Only few reports of renal biopsy performed in patients with TAFRO syndrome exist. CASE PRESENTATION: A 61-year-old woman, with a history of Sjogren's syndrome, was admitted to our hospital with anasarca and abdominal distension. Based on the clinical course and various laboratory findings, we diagnosed TAFRO syndrome. Renal biopsy revealed thrombotic microangiopathy, including endothelial cell swelling, subendothelial space expansion, and mesangiolysis. She was treated with oral prednisolone and cyclosporine, with consequent resolution of anasarca, pleural effusion, and ascites, and improvement in renal function and urinary findings. The patient's platelet count also normalized after 2 months of treatment. CONCLUSIONS: Given that only few reports of improvement in the systemic symptoms of TAFRO syndrome using steroids and cyclosporine exist, our study investigating the relationship between the pathogenesis of TAFRO syndrome and renal disorders, as well as treatment methods, provides valuable insights.

Regorafenib-induced renal-limited thrombotic microangiopathy: a case report and review of literatures.

BACKGROUND: Regorafenib belongs to a sub-group of small-molecule multi-targeted tyrosine kinase inhibitors(TKIs). In various studies with respect to the side-effect of regorafenib, drug-associated proteinuria standardly qualified to be defined as nephrotic syndrome was rarely reported as well as the relation of regorafenib with the occurrence and development of thrombotic microangiopathy (TMA). CASE PRESENTATION: In this case report and literature review, we presented a 62-year-old patient receiving regorafenib for metastatic colon cancer, manifesting abundant proteinuria, in which TMA was also diagnosed through renal biopsy. As far as we were concerned, this was the first reported in terms of regorafenib-induced TMA confirmed by renal biopsy. CONCLUSION: This case indicates that regorafenib, a kind of TKIs may result in TMA, which is a rare but life-threatening complication of cancer treatment drug. Insights from this case might help physicians diagnose rare forms of TMA and adjust treatment for patients in a timely manner.

Pregnancy associated TMA in 13-year-old patient successfully treated with Eculizumab: case report.

BACKGROUND: This report introduces an unusual cause of kidney failure in a previously healthy pediatric patient. She developed thrombotic microangiopathy (TMA) that was diagnosed post-partum, requiring dialysis and eculizumab, with eventual recovery of kidney function ([chronic kidney disease (CKD) stage 3]. CASE PRESENTATION: The patient was induced at term due to preeclampsia, with delivery complicated by severe postpartum hemorrhage from uterine atony. She continued to have severe hypertension post-delivery and further developed acute kidney injury (AKI) with decreased urinary output and respiratory distress requiring dialysis therapy. Labs revealed hemolysis with elevated lactate dehydrogenase, low haptoglobin, anemia, and thrombocytopenia, but otherwise unremarkable immunology labs. Once clinically stabilized the patient underwent kidney biopsy, which was consistent with TMA. Treatment was initiated with eculizumab, a monoclonal antibody for terminal complement blockade. Her clinical status improved (including markers of hemolysis and inflammation) with kidney replacement therapy and complement blockade. On discharge, she had increasing urine output and was prescribed 3 day per week hemodialysis and twice monthly eculizumab infusions. By 6 weeks post-delivery, hemodialysis was discontinued and her eculizumab was weaned to monthly infusions. Eculizumab was discontinued at 12 months postpartum. Genetic testing for mutations of the complement system was negative. The patient has residual stage 3 CKD with stable kidney function, requiring two agents for blood pressure control, including an ACE inhibitor for antiproteinuric effect. CONCLUSIONS: This case report showcases an unusual cause of renal failure in a pediatric patient due to TMA in the post-partum period. She required intermittent hemodialysis (iHD) for a brief period, however she was treated successfully with eculizumab that was able to be weaned off 1 year after delivery. She has residual stage 3 CKD and no further signs or symptoms of TMA.

Renal thrombotic microangiopathy and nephrotic proteinuria induced by intravitreal injection of aflibercept for diabetic macular edema.

BACKGROUND: Vascular endothelial growth factor inhibitors (VEGFIs) are used to treat malignant neoplasms and ocular diseases by inhibiting angiogenesis. Systemic use of VEGFIs has various side effects, including hypertension, proteinuria, and thrombotic microangiopathy, but adverse events due to intravitreal injection of VEGFIs have not been fully clarified. Although age-related macular degeneration was initially the most common target of intravitreal injection of VEGFIs, it has also been applied sporadically for diabetic macular edema in recent years. Proteinuria following intravitreal injection of VEGFIs would be reversible. In patients with diabetes mellitus (DM), however, it would be difficult to determine whether kidney damage arises from the clinical course of DM or from intravitreal injection of VEGFIs for diabetic macular edema. CASE PRESENTATION: A 55-year-old woman with a 20-year history of type 2 DM began intravitreal injection of VEGFI (aflibercept, 2 mg every 4 weeks) for treatment of diabetic macular edema 2 years previously. She presented with leg edema, hypertension, and nephrotic-range proteinuria 14 months after the first injection. Histological examination of renal biopsy specimens revealed diabetic nephropathy with renal thrombotic microangiopathy probably associated with intravitreal injection of VEGFI. The patient's nephrotic syndrome completely improved at 6 months after simply discontinuing aflibercept. CONCLUSIONS: This is a precious report of pathologically investigated renal thrombotic microangiopathy leading to nephrotic syndrome due to intravitreal injection of aflibercept for diabetic macular edema in a patient with type 2 DM. Renal function and proteinuria should be monitored in diabetic patients who receive intravitreal injection of a VEGFI. If kidney damage develops independent of the clinical course of DM during intravitreal injection of a VEGFI, renal biopsy should be performed and intravitreal VEGFI injection discontinued.

[A case of thrombotic microangiopathy during chemotherapy with gemcitabine in a patient with pancreatic cancer].

A 57-year-old male patient with unresectable pancreatic head cancer was treated with chemotherapy, 5 courses of gemcitabine plus nab paclitaxel therapy, and 9 courses of gemcitabine monotherapy. After 12 months of treatment, he was admitted to our hospital with headache and dyspnea. He was diagnosed with gemcitabine-induced thrombotic microangiopathy (TMA) due to acute kidney dysfunction, hemolytic anemia, and thrombocytopenia. Gemcitabine was discontinued, and symptoms were improved without using hemodialysis and plasma exchange. After his renal function recovered, we started S-1 chemotherapy. Eighteen months later, the patient was alive. Looking back, we realized that fragment red blood cells appeared in complete blood count and serum LDH elevated at 5 months prior to admission, serum creatinine level increased slowly at 4 months prior to admission, and blood pressure elevated significantly at 2 months prior to admission. Therefore, physicians must be aware of TMA as a possible adverse event to gemcitabine. As in this case, hemolytic findings and hypertension in patients treated with gemcitabine may help early detection of TMA.

The long-acting C5 inhibitor, ravulizumab, is effective and safe in pediatric patients with atypical hemolytic uremic syndrome naïve to complement inhibitor treatment.

Ravulizumab, a long-acting complement C5 inhibitor engineered from eculizumab, allows extending maintenance dosing from every 2-3 weeks to every 4-8 weeks depending on bodyweight. Here, we evaluated the efficacy and safety of ravulizumab in complement inhibitor-naïve children (under 18 years) with atypical hemolytic uremic syndrome. In this phase III, single-arm trial, ravulizumab was administered every eight weeks in patients 20 kg and over, and four weeks in patients under 20 kg. The primary endpoint was a complete thrombotic microangiopathy response (normalization of platelet count and lactate dehydrogenase, and a 25% or more improvement in serum creatinine) through 26 weeks. Secondary endpoints included change in hematologic parameters and kidney function. 18 patients with a median age of 5.2 years were evaluated. At baseline, symptoms of atypical hemolytic uremic syndrome outside the kidney were present in 72.2% of patients and 38.9% had been in intensive care. Baseline estimated glomerular filtration rate was 22 mL/min/1.73 m2. By week 26, 77.8% of patients achieved a complete thrombotic microangiopathy response; 94.4%, 88.9% and 83.3% of patients achieved platelet normalization, lactate dehydrogenase normalization and a 25% or more improvement in serum creatinine, respectively. By week 50, 94.4% patients had achieved a complete thrombotic microangiopathy response. Median improvement in platelet count was 246 and 213 x109/L through week 26 and week 50, respectively. The median increase above baseline in estimated glomerular filtration rate was 80 and 94 mL/min/1.73m2 through week 26 and week 50, respectively. No unexpected adverse events, deaths, or meningococcal infections occurred. Thus, ravulizumab rapidly improved hematologic and kidney parameters with no unexpected safety concerns in complement inhibitor-naïve children with atypical hemolytic uremic syndrome.

Transplant-associated thrombotic microangiopathy and immune haematological complications following intestine-containing organ transplantation: experience from over 100 consecutive cases.

Descriptions of passenger lymphocyte syndrome (PLS), immune cytopenias and transplant-associated thrombotic microangiopathy (TA-TMA) after intestine-containing transplants remain scarce. We describe our centre's experience of these complications from 2007 to 2019. Ninety-six patients received 103 transplants. PLS occurred in 9 (9%) patients (median 12 days post-transplant); all due to ABO antibodies. There were 31 minor ABO mismatch transplants. No patient required change in immunosuppression. Immune cytopenias (excluding PLS) occurred in six patients at an incidence of 1·7/100 patient years; three immune haemolysis, one immune thrombocytopenia, one acquired Glanzmann's and one immune neutropenia; 50% occurred with other cytopenias. All cases eventually responded to treatment, with a median of four treatments (range 1-8) and 5/6 were treated with rituximab. One patient with immune haemolysis required bortezomib. Complications were common in patients with immune cytopenias; 4/6 with infection needing intravenous antibiotics and 3/6 with venous thromboembolism. In 3/6 cases, a secondary cause for the immune cytopenia was evident. Switching from tacrolimus to ciclosporin was not necessary. There were five cases of transplant-associated thrombotic microangiopathy (TA-TMA; 1·5/100 patient years) requiring calcineurin inhibitor withdrawal; two cases associated with acute rejection. Two cases were managed with plasma exchange, one with plasma infusions and one with eculizumab. Further research in this patient group is required.

Complement as the enabler of carfilzomib-induced thrombotic microangiopathy.

Carfilzomib has been associated with the development of thrombotic microangiopathy (TMA) in relapsed/refractory multiple myeloma patients, a severe disease with no currently available aetiological treatment. We evaluated the potential role of terminal complement pathway in four patients with carfilzomib-induced TMA. Membrane attack complex (C5b-9) deposition on endothelial cells in culture exposed to plasma from patients during the acute phase of the disease suggests complement overactivation as a mechanism of potential endothelial damage in three out of four patients. If confirmed in larger cohorts, C5b-9 evaluation will allow early identification of patients who could benefit from complement blockade and treatment monitoring.

MASP2 levels are elevated in thrombotic microangiopathies: association with microvascular endothelial cell injury and suppression by anti-MASP2 antibody narsoplimab.

Involvement of the alternative complement pathway (AP) in microvascular endothelial cell (MVEC) injury characteristic of a thrombotic microangiopathy (TMA) is well documented. However, the role of the lectin pathway (LP) of complement has not been explored. We examined mannose-binding lectin associated serine protease (MASP2), the effector enzyme of the LP, in thrombotic thrombocytopenic purpura, atypical hemolytic uremic syndrome and post-allogeneic hematopoietic stem cell transplantation (alloHSCT) TMAs. Plasma MASP2 and terminal complement component sC5b-9 levels were assessed by enzyme-linked immunosorbent assay (ELISA). Human MVEC were exposed to patient plasmas, and the effect of the anti-MASP2 human monoclonal antibody narsoplimab on plasma-induced MVEC activation was assessed by caspase 8 activity. MASP2 levels were highly elevated in all TMA patients versus controls. The relatively lower MASP2 levels in alloHSCT patients with TMAs compared to levels in alloHSCT patients who did not develop a TMA, and a significant decrease in variance of MASP2 levels in the former, may reflect MASP2 consumption at sites of disease activity. Plasmas from 14 of the 22 TMA patients tested (64%) induced significant MVEC caspase 8 activation. This was suppressed by clinically relevant levels of narsoplimab (1·2 µg/ml) for all 14 patients, with a mean 65·7% inhibition (36.8-99.4%; P < 0·0001). In conclusion, the LP of complement is activated in TMAs of diverse etiology. Inhibition of MASP2 reduces TMA plasma-mediated MVEC injury in vitro. LP inhibition therefore may be of therapeutic benefit in these disorders.