A new paradigm: Diagnosis and management of HSCT-associated thrombotic microangiopathy as multi-system endothelial injury

Incidence, risk factors, and outcomes of transplant-associated thrombotic microangiopathy in pediatric patients after allogeneic hematopoietic cell transplantation: a single-institution prospective study

Transplant-associated thrombotic microangiopathy (TA-TMA) is an increasingly recognized complication in hematopoietic cell transplantation (HCT). Given the rarity of prospective pediatric studies on TA-TMA, this study aimed to evaluate the incidence, survival outcomes, and risk factors for predicting early the development of TA-TMA in a pediatric population following allogeneic HCT. We conducted a prospective analysis of 173 pediatric patients to evaluate the incidence, survival outcome, and risk factors of TA-TMA. The cumulative incidence of TA-TMA at one-year post-HCT was 4.7% (95% CI, 2.2-8.6%). Patients with TA-TMA showed significantly poorer 1-year overall survival (OS) rate, 50.0% ± 17.7% compared to 85.4% ± 2.8% in those without TA-TMA (p = 0.008). Additionally, the non-relapse mortality (NRM) rate was higher in the TA-TMA group at 12.5% (95% CI, 3.7-55.8%) versus 7.0% (95% CI, 2.8-10.1%) (p = 0.598). A urine protein/creatinine ratio ≥ 1 mg/mg on day 30 post-HCT was significantly associated with TA-TMA occurrence (adjusted HR, 9.5; [95% CI], 1.28-70.39; p = 0.028). This study showed the significantly unfavorable clinical outcomes associated with TA-TMA in pediatric patients and emphasized the importance of early identification of patients at risk. Further research is needed to explore additional strategies for early detection and intervention to improve outcomes.

Concurrent hemophagocytic lymphohistiocytosis and thrombotic microangiopathy in a patient with Epstein-Barr virus infection and gastric adenocarcinoma: the puzzle started with microangiopathic hemolytic anemia

Malignancy-associated-hemophagocytic lymphohistiocytosis (HLH) is rare and often seen in high-grade lymphomas and acute leukemias; solid-tumor-associated HLH is extremely uncommon. The diagnosis of malignancy-associated-HLH remains challenging in clinical practices as it masquerades as and coexists with many other conditions. Here we presented a case with concurrent solid-tumor-associated HLH and thrombotic microangiopathy. The patient was an 80-year-old male with microangiopathic hemolytic anemia (MAHA), progressive bi-lineage cytopenia, and active Epstein-Barr virus (EBV) infection. Extensive lab works excluded all other alternative etiologies for MAHA but B12 deficiency, malignancy, and EBV infection. Concurrently, poorly differentiated gastric adenocarcinoma-associated HLH and thrombotic microangiopathy (TMA) were confirmed with extensive lab work. This patient passed away despite high-dose dexamethasone treatment. In the paper, we also discussed the possible pathophysiology of EBV infection in the development of MAHA and HLH and reviewed the treatment options for HLH and TMA.

Modified G-CSF/ATG-Based Haploidentical Transplantation Protocol in Pediatric Primary Hemophagocytic Lymphohistiocytosis: A Long-Term Follow-Up Single-Center Experience

BACKGROUND

Primary hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory syndrome caused by immune dysregulation. Hematopoietic stem cell transplantation (HSCT) represents the only option for long-term cure for primary HLH. However, only around 25% of patients have a fully HLA-matched donor.

METHODS

In this retrospective study, we analyzed 42 pediatric patients with primary HLH who underwent haplo-SCT using the modified granulocyte colony-stimulating factor (G-CSF)/antithymocyte globulin (ATG)-based protocol. The conditioning regimen included 300-600 mg/m2 etoposide (VP16), along with low doses of busulfan (Bu) (0.8-1.2 mg/kg every 6 hours on Days -8 to -6), cyclophosphamide (Cy) (10 mg/kg/day on Days -4 to -3), fludarabine (Flu) (30 mg/m2/day on Days -5 to -3), and ATG (8-9 mg/kg total dose on Days -5 to -2) to reduce complications.

RESULTS

All 42 patients achieved successful engraftment. Following a median follow-up period of 48.7 months, 32 of the 42 patients remained alive and disease free. The 2-year overall survival (OS) rate was 78.4%, and the 5-year OS rate was 73.7%. The 2-year failure-free survival (FFS) rate was 71.3%, and the 5-year FFS rate was 66.5%. Patients who achieved complete remission at the time of HSCT showed better OS (p < 0.05). The incidence of Grade III-IV acute graft-versus-host disease (GVHD) was 26.2%, and severe chronic GVHD was observed in 11.9% of patients. Thrombotic microangiopathy occurred in 13 patients, and veno-occlusive disease in two patients.

CONCLUSIONS

This modified G-CSF/ATG-based haploidentical protocol demonstrates significant potential for pediatric patients with primary HLH, exhibiting commendable effectiveness and safety.

Complement activation and vascular complications after pediatric allogeneic hematopoietic stem cell transplantation

Treatment-related toxicity remains a challenge in pediatric hematopoietic stem cell transplantation (HSCT). In this prospective, single-center study we studied activation of the complement system peri- and post-transplant through plasma C3a and SC5b-9. We also studied acute adverse events and key vascular complications and analyzed their possible relationship to complement activation. Out of 42 patients, 39 (92.9%) had at least one adverse event (grade 2-4) during the first 100 days post-transplant, and 23 (54.8%) at least one severe (grade 3 or 4) event. We identified a total of 4/42 (9.5%) patients with capillary leak syndrome (CLS), veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS) or thrombotic microangiopathy (TMA). 50% of the patients with endotheliopathy died of toxicity. Complement activation was assessed in 26 patients. HSCT was accompanied with increases in blood C3a, peri-transplant C3a peaked at 30 min and 24 h. During the first 6 months post-transplant ten patients showed at least a 50% elevation in SC5b-9, but this did not clearly correlate with clinical adverse events. One patient with severe TMA had a significant increase in SC5b-9 peaking at 1-month post-transplant at nearly 40 times the pre-transplant level. Terminal complement activation thus appears to be linked only to clinically significant HSCT-TMA.

Dasatinib-induced renal (or chronic) thrombotic microangiopathy in a patient with chronic myeloid leukemia: A case report

Thrombotic microangiopathy encompasses microvascular thrombosis, hemolytic anemia, thrombocytopenia, and end-organ damage. Secondary thrombotic microangiopathy can result from malignancies, autoimmune diseases, or treatments such as tyrosine kinase inhibitors. Dasatinib, a tyrosine kinase inhibitor used in managing chronic myeloid leukemia, has been linked to thrombotic microangiopathy. This report describes a 66-year-old female with chronic myeloid leukemia treated with dasatinib who developed renal-limited thrombotic microangiopathy. Progressive renal dysfunction found in the context of chronic kidney disease prompted extensive lab evaluation and evaluation, with a renal biopsy confirming thrombotic microangiopathy attributed to dasatinib-induced nephrotoxicity. Discontinuation of dasatinib led to a slight improvement in renal function; however, progressive decline necessitated dialysis. This case underscores the diagnostic and therapeutic challenges of dasatinib-induced thrombotic microangiopathy, emphasizing renal biopsy in diagnosis and monitoring. Individualized treatment strategies and further research should be conducted to optimize future outcomes.

Validation and performance of MicroVue sC5b-9 Plus ELISA on the Dynex DS2 platform

BACKGROUND

The complement membrane attack complex involves C5b-mediated assembly of C6-C9 polymers to form pores in cell membranes during complement activation. Inactive complexes can become soluble C5b-9 (sC5b-9) when they bind to Protein S. Elevated sC5b-9 levels are associated with increased risk of hematopoietic stem cell transplant-associated thrombotic microangiopathy (TA-TMA), a serious condition which can be improved with eculizumab therapy. Early detection of TA-TMA is essential for improving patient outcomes and optimizing the use of this costly treatment. We assessed the Quidel Microvue sC5b-9 Plus Enzyme Immunoassay on the Dynex-DS2 platform to screen for patients at risk of TA-TMA.

METHODS

EDTA plasma samples were collected from bone marrow transplant (BMT) patients and others not at risk for TA-TMA. Assay validation included correlation with another laboratory, precision, linearity, and hemolysis interference. Additionally, clinical accuracy was assessed through retrospective patient data analyses.

RESULTS

The assay showed acceptable intra- and interday precision, with less than 13 % variation. Linearity ranged from 80 to 1600 ng/mL, and there was no hemolysis interference up to 800 mg/dL. Clinical data revealed that monitoring sC5b-9 levels could detect significant increases indicative of TA-TMA, facilitating timely eculizumab intervention. Analytically, changes in sC5b-9 by 2- to 3-fold were significant for patient monitoring of TA-TMA. Lastly, a retrospective analysis on utility of the assay demonstrated effective utilization at our institution.

CONCLUSION

The Quidel Microvue sC5b-9 Plus Enzyme Immunoassay demonstrated good analytical and clinical performance in screening patients with increased risk of TA-TMA.

The Adverse Event Landscape of Stem Cell Transplant: Evidence for AGVHD Driving Early Transplant Associated Toxicities

Although unrelated-donor (URD) hematopoietic cell transplantation (HCT) is associated with many toxicities, a detailed analysis of adverse events, as defined by the Common Terminology Criteria for Adverse Events (CTCAE), has not previously been curated. This represents a major unmet need, especially as it relates to assessing the safety of novel agents. We analyzed a detailed AE database from the "ABA2" randomized, double-blind, placebo-controlled clinical trial of abatacept for acute graft-versus-host disease (AGVHD) prevention, for which the FDA mandated a detailed AE assessment through Day +180, and weekly neutrophil and platelet counts through Day +100. These were analyzed for their relationship to key transplant outcomes, with a major focus on the impact of AGVHD on the development/severity of AEs. A total of 2102 AEs and 1816 neutrophil/platelet counts were analyzed from 142 8/8-HLA-matched URD HCT recipients on ABA2 (placebo cohort, n = 69, abatacept cohort, n = 73). This analysis resulted in 2 major observations. (1) Among graft source, conditioning intensity, age, and Grade 2 to 4 AGVHD, only AGVHD impacted Grade 3 to 5 AE acquisition after the first month post-transplant. (2) The development of Grade 3 to 4 AGVHD was associated with thrombocytopenia. We have created a detailed resource for the transplant community by which to contextualize clinical toxicities after transplant. It has identified AGVHD as a major driver of post-HCT Grade 3 to 5 AEs, and underscored a link between AGVHD and thrombocytopenia. This establishes a critical safety framework upon which the impact of novel post-transplant AGVHD therapeutics should be evaluated. This trial was registered at www.clinicaltrials.gov (#NCT01743131).

Kidney Disease and Hematopoietic Stem Cell Transplantation

Hematopoietic stem cell transplantation (HSCT) is a potentially curative therapy for patients with hematologic malignancies and certain solid tumors and nonmalignant hematologic conditions. Both AKI and CKD occur commonly after HSCT and are associated with significant morbidity and mortality. AKI and CKD in this setting may result from direct effects of the transplant or be caused by pretransplant bone marrow conditioning regimens and/or nephrotoxic agents administered in the post-transplant period. In this article, we review the epidemiology, risk factors, etiologies, pathophysiology, diagnosis, prevention, and treatment of post-HSCT AKI and CKD, with special attention to recent advances in this fast-moving and evolving field.

Tacrolimus-induced thrombotic microangiopathy (TMA) after heart and lung transplantation successfully treated with eculizumab

INTRODUCTION

Tacrolimus-induced thrombotic microangiopathy (TMA) causing acute kidney injury (AKI) without systemic features is a rare entity, particularly after non-renal solid organ transplantation.

CASE REPORT

We describe the case of a patient with AKI after combined heart and lung transplantation. Renal biopsy revealed acute thrombotic microangiopathy which ultimately prompted initiation of eculizumab, a monoclonal antibody targeted against complement C5, with subsequent recovery in renal function.

RESULTS/CONCLUSION

This case highlights renal isolated drug-induced TMA as a rarely reported cause of AKI post heart-lung transplantation. We emphasize the importance of performing a renal biopsy in guiding management strategies.

Endothelial dysfunction in acute ischemic stroke: a review

BACKGROUND AND PURPOSE

Endothelial dysfunction is considered an emerging therapeutic target to prevent complications during acute stroke and to prevent recurrent stroke. This review aims to provide an overview of the current knowledge on endothelial dysfunction, outline the diagnostic methods used to measure it and highlight the drugs currently being investigated for the treatment of endothelial dysfunction in acute ischemic stroke.

METHODS

 The PubMed® and ClinicalTrials.gov electronic databases were searched for eligible articles/studies dealing with endothelial dysfunction and stroke. The references of the articles were screened to identify additional sources. The data were abstracted and summarized.

FINDINGS AND DISCUSSION

Endothelial dysfunction can be measured by serum biomarkers as well as by ultrasound or plethysmography techniques. Drugs targeting endothelial dysfunction include widely used agents such as angiotensin-converting enzyme inhibitors or isosorbide mononitrate, but also experimental therapies such as endothelial progenitor cells.

CONCLUSION

The role of endothelial dysfunction in acute ischemic stroke has been studied increasingly in recent years. It has been shown that there is a correlation between endothelial dysfunction and parenchymal hematoma after endovascular thrombectomy. Also, early clinical trials are conducted investigating, e.g., endothelial progenitor cells in the treatment of endothelial dysfunction in ischemic stroke. Current research focuses on the integration of novel markers of endothelial dysfunction into routine clinical practice to support decision making in the treatment of acute ischemic stroke.

Clinical Manifestations and Prognosis of Chronic Kidney Disease after Hematopoietic Stem Cell Transplantation

Introduction

Kidney disease is a common complication of hematopoietic stem cell transplantation (HSCT). However, there is limited research on the clinical pathology and prognosis of patients who develop chronic kidney disease (CKD) after HSCT.

Methods

A retrospective analysis was conducted on 50 patients diagnosed with CKD through kidney biopsy between September 2008 and May 2024. The patients were categorized based on their pathological presentations into groups with thrombotic microangiopathy (TMA) or membranous nephropathy (MN).

Results

The renal pathological results revealed that TMA was the most prevalent pathological type, accounting for 40% of cases, followed by MN at 32%, and mesangial proliferative glomerulonephritis at 16%, among others. Clinically, patients with TMA predominantly presented with renal insufficiency, whereas those with MN mainly exhibited nephrotic syndrome. Patients with MN showed favorable responses to treatment, achieving complete and partial response rates of 14.3% and 71.4%, respectively. Among the 50-patient cohort, 45 remained alive, corresponding to a 5-year overall survival rate of 87.8%. The 5-year renal survival rate was observed to be 78.8%, with 3 patients (6.98%) requiring kidney replacement therapy.

Conclusion

TMA and MN are the two most common pathological findings in patients with CKD following HSCT. Both conditions exhibit favorable responses to combined steroids and immunosuppressant therapy. Notably, patients with MN demonstrate a higher overall response rate and superior treatment outcomes compared to those with TMA.

Endothelial Activation and Stress Index (EASIX): A Prognostic Marker for Mortality After Acute Graft-Versus-Host Disease and Endothelial Complications

Acute graft-versus-host disease (aGVHD) is a potentially life-threatening complication after allogeneic stem cell transplantation (alloSCT) commonly treated with steroids. Steroid-refractory aGVHD is associated with thrombotic microangiopathy (TAM), supporting the notion of endothelial dysfunction as a risk factor for poor prognosis. Several diagnostic criteria exist to diagnose TAM; however, emerging data points to the clinical importance of the endothelial activation and stress index (EASIX) as biomarker in the context of alloSCT. The EASIX integrates three basic lab parameters (serum lactate dehydrogenase and creatinine concentrations with platelet counts) into one ratio that produces continuous values to allow monitoring of impending endothelial complications after alloSCT. This chapter provides an overview of the use of EASIX as prognostic marker for mortality after aGVHD and endothelial complications.

Non-infectious pulmonary complications after haematopoietic progenitor transplantation: a diagnostic approach

Haematopoietic stem cell transplantation (HCT) is an established treatment for a wide variety of haematological diseases, both malignant and non-malignant. Infectious and non-infectious post-HCT pulmonary complications are a major cause of morbidity and mortality, with non-infectious complications becoming more prominent in recent decades as prophylaxis has led to a decrease in infectious complications. Globally, these complications can be divided into three phases (neutropenic, early and late phase) depending on their time of onset in relation to the graft. There is a growing awareness that the assessment of the patient undergoing HCT should start before the transplantation itself. It is known that total body irradiation dose, the source of HCT, myeloablative regimens or lower baseline lung function are key risk factors in the development of pulmonary complications. In general, the treatment of these entities consists of administration of corticosteroids with variable response, which highlights the need to better understand the underlying biology in order to have new drugs with more directed targets to improve the prognosis of post-HCT non-infectious pulmonary complications. In view of the limited therapeutic response mentioned above, preventive measures for patients undergoing HCT, such as conditioning of less ablative regimens or pre-selection of high-risk cases, are of paramount importance in order to mitigate the severity of these devastating pulmonary complications.

Transplant-associated TMA: the conundrum of diagnosis and treatment

Transplant-associated thrombotic microangiopathy (TA-TMA) after hematopoietic cell transplantation is characterized by microangiopathic hemolytic anemia (MAHA) with persistent schistocytosis, elevated markers of hemolysis, thrombocytopenia, and microvascular thrombosis leading to ischemic injuries in the kidneys and other organs. The initial evaluation of the disease requires confirmation of non-immune MAHA and careful examination of known secondary causes of TMA. Due to increased likelihood of long-term renal failure and overall mortality, a rapid diagnosis and treatment of the underlying trigger is needed. However, the diagnostic criteria proposed to define TA-TMA remain insufficient. sC5b9, the soluble form of the membrane attack complex of the terminal complement pathway, is the most studied prognostic biomarker for the disease, though its sensitivity and specificity remain suboptimal for clinical use. Current evidence does not support the cessation of calcineurin inhibitors without cause or the use of therapeutic plasma exchange. Many recent single-arm studies targeting the complement pathway inhibition have been reported, and larger randomized controlled trials are ongoing. This review aims to provide an evidence-based discussion from both adult and pediatric perspectives on the advances and conundrums in TA-TMA diagnosis and treatment.

Hemostasis and complement in allogeneic hematopoietic stem cell transplantation: clinical significance of two interactive systems

Hematopoietic stem cell transplantation (HCT) represents a curative treatment option for certain malignant and nonmalignant hematological diseases. Conditioning regimens before HCT, the development of graft-versus-host disease (GVHD) in the allogeneic setting, and delayed immune reconstitution contribute to early and late complications by inducing tissue damage or humoral alterations. Hemostasis and/or the complement system are biological regulatory defense systems involving humoral and cellular reactions and are variably involved in these complications after allogeneic HCT. The hemostasis and complement systems have multiple interactions, which have been described both under physiological and pathological conditions. They share common tissue targets, such as the endothelium, which suggests interactions in the pathogenesis of several serious complications in the early or late phase after HCT. Complications in which both systems interfere with each other and thus contribute to disease pathogenesis include transplant-associated thrombotic microangiopathy (HSCT-TMA), sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD), and GVHD. Here, we review the current knowledge on changes in hemostasis and complement after allogeneic HCT and how these changes may define clinical impact.

Epidemiology of Diffuse Alveolar Hemorrhage in Pediatric Allogeneic Hematopoietic Cell Transplantation Recipients

Diffuse alveolar hemorrhage (DAH) is a life-threatening pulmonary toxicity that can arise after hematopoietic cell transplantation (HCT). Risk factors and outcomes are not well understood owing to a sparsity of cases spread across multiple centers. The objectives of this epidemiologic study were to characterize the incidence, outcomes, transplantation-related risk factors and comorbid critical care diagnoses associated with post-HCT DAH. Retrospective analysis was performed in a multicenter cohort of 6995 patients age ≤21 years who underwent allogeneic HCT between 2008 and 2014 identified through the Center for International Blood and Marrow Transplant Research registry and cross-matched with the Virtual Pediatric Systems database to obtain critical care characteristics. A multivariable Cox proportional hazard model was used to determine risk factors for DAH. Logistic regression models were used to determine critical care diagnoses associated with DAH. Survival outcomes were analyzed using both a landmark approach and Cox regression, with DAH as a time-varying covariate. DAH occurred in 81 patients at a median of 54 days post-HCT (interquartile range, 23 to 160 days), with a 1-year post-transplantation cumulative incidence probability of 1.0% (95% confidence interval [CI], .81% to 1.3%) and was noted in 7.6% of all pediatric intensive care unit patients. Risk factors included receipt of transplantation for nonmalignant hematologic disease (reference: malignant hematologic disease; hazard ratio [HR], 1.98; 95% CI, 1.22 to 3.22; P = .006), use of a calcineurin inhibitor (CNI) plus mycophenolate mofetil (MMF) as graft-versus-host disease (GVHD) prophylaxis (referent: CNI plus methotrexate; HR, 1.89; 95% CI, 1.07 to 3.34; P = .029), and grade III-IV acute GVHD (HR, 2.67; 95% CI, 1.53-4.66; P < .001). Critical care admitted patients with DAH had significantly higher rates of systemic hypertension, pulmonary hypertension, pericardial disease, renal failure, and bacterial/viral/fungal infections (P < .05) than those without DAH. From the time of DAH, median survival was 2.2 months, and 1-year overall survival was 26% (95% CI, 17% to 36%). Among all HCT recipients, the development of DAH when considered was associated with a 7-fold increase in unadjusted all-cause post-HCT mortality (HR, 6.96; 95% CI, 5.42 to 8.94; P < .001). In a landmark analysis of patients alive at 2 months post-HCT, patients who developed DAH had a 1-year overall survival of 33% (95% CI, 18% to 49%), compared to 82% (95% CI, 81% to 83%) for patients without DAH (P < .001). Although DAH is rare, it is associated with high mortality in the post-HCT setting. Our data suggest that clinicians should have a heightened index of suspicion of DAH in patients with pulmonary symptoms in the context of nonmalignant hematologic indication for HCT, use of CNI + MMF as GVHD prophylaxis, and severe acute GVHD. Further investigations and validation of modifiable risk factors are warranted given poor outcomes.

The efficacy and safety of third-party umbilical blood/umbilical cord mesenchymal stem cell assisted related haploid hematopoietic stem cell transplantation in pediatric patients with acute leukemia: an observational study

Background

There is limited data on third-party umbilical cord blood (UCB) or mesenchymal stem cell (MSC) transplantation-assisted haploidentical hematopoietic stem cell transplantation (haplo-HSCT) in pediatric patients.

Objective

To evaluate the efficacy and safety of UCB and MSC transplantation-assisted haplo-HSCT in pediatric patients with acute leukemia (AL).

Design

Observational study.

Methods

Clinical data of 152 children with AL undergoing haplo-HSCT at the Children's Hospital of Soochow University between January 2020 and June 2022 were collected. The patients were divided into the haplo-HSCT + UCB group (n = 76), haplo-HSCT + MSC group (n = 31), and haplo-HSCT group (n = 45). Hematopoietic reconstruction time, complications within 30 days after transplantation, and survival and recurrence at 3 years after transplantation were compared among the groups.

Results

Multivariate analysis revealed that haplo-HSCT with MSC and human leukocyte antigen (HLA) matching ⩾6/10 were independent factors reducing engraftment syndrome (ES) incidence. There were no significant differences among the groups in the hematopoietic reconstruction time or incidence of complications within 30 days after transplantation (p > 0.05). Overall survival, relapse-free survival, cumulative incidence of relapse, cumulative incidence of hematological relapse, and 3-year transplant-related mortality were not significantly different (p > 0.05). The incidence of adverse reactions in the haplo-HSCT + UCB group was 97.3% within 4 h after UCB infusion, with a particularly high occurrence rate of 94.7% for hypertension. No transfusion-related adverse reactions occurred after the transfusion of umbilical cord MSC in the haplo-HSCT + MSC group.

Conclusion

MSC-assisted haplo-HSCT can reduce ES incidence after transplantation in pediatric patients with AL. UCB infusion is associated with a high incidence of reversible hypertension. However, no adverse reactions were observed in umbilical cord MSC transfusion.

Real-World Application of Recently Proposed ASTCT/CIBMTR/EBMT/APBMT Consensus Risk Stratification for Transplantation-Associated Thrombotic Microangiopathy in Children

Consensus diagnostic and risk stratification of transplantation-associated thrombotic microangiopathy (TA-TMA) was recently achieved from international transplantation groups. Although the proposed diagnostic criteria have been applied to multiple pediatric cohorts, there are scant data applying the novel risk stratification approach in children with TA-TMA. In this retrospective cohort study, all children undergoing an allogeneic HCT or autologous HCT for neuroblastoma were prospectively screened for TA-TMA, diagnosed, and risk-stratified using the Jodele criteria from August 2019 to October 2023. Our institutional practice during the study period was treat all Jodele intermediate-risk (IR) and high-risk (HR) patients with eculizumab. Harmonization risk stratification criteria were applied retrospectively. All survival analyses were calculated from the day of TA-TMA diagnosis. To identify which specific harmonization high-risk features were the most important predictors for nonrelapse mortality (NRM), full and reduced logistical regression models were tested. The lowest Bayes information criterion and optimal Mallows CP statistic were used to identify the best subset. The analysis was performed with SAS 9.4 (SAS Institute, Cary, NC). Fifty-two children were diagnosed with TA-TMA during the study period, at a median of 37.5 days post-HCT (range, 3 to 735 days). Using Jodele risk stratification, 11 (21%) were SR, 21 (40%) were IR, and 20 (39%) were HR. Forty (77%) were treated with eculizumab. There were no statistically significant differences in NRM among Jodele risk groups, although overall survival (OS) differed significantly. Using the harmonized stratification, 49 children (94%) were stratified as HR and 3 as standard risk (SR), there were no statistically significant differences in NRM or OS between groups. Eight children (15.4%) were classified as SR using Jodele risk stratification but restratified as HR using the harmonization criteria. One child (12.5%) died in the setting of severe GVHD, and the remaining 7 were alive at the last follow-up. In a best subset model, lactate dehydrogenase (LDH) level >2 times the upper limit of normal (ULN) (odds ratio [OR], 6.52, 95% confidence interval [CI], .96 to 44.3; P = .05), grade II-IV acute graft-versus-host disease (GVHD) at the time of TA-TMA diagnosis (OR, 15.4; 95% CI, 2.14 to 110.68; P = .01), and organ dysfunction at the time of TA-TMA (OR, 21.5; 95% CI, 2.96 to 156.37; P = .002) were significantly associated with NRM; elevated sC5b-9, urine protein/creatinine ratio, and viral infections were not significantly associated with NRM. Using these best-fit criteria, 14 patients were classified as SR and 38 were classified as HR, NRM was significantly higher, and OS was significantly lower. In this cohort of children with TA-TMA, retrospective application of the harmonization criteria resulted in more patients stratified as HR compared to use of the previously described Jodele criteria. The intention of the harmonization criteria was to identify those at greatest risk of poor outcomes; while all harmonization SR patients survived, this risk stratification was very sensitive. Previous criticisms of harmonization risk stratification include limited access to sC5b-9 testing. These data suggest that organ dysfuncion, acute GVHD, and LDH >2 times ULN are the most important predictors of NRM in this cohort, allowing risk stratification even in the absence of available sC5b-9 testing. Additional studies are needed to validate these findings.

Atypical hemolytic uremic syndrome during induction chemotherapy in neuroblastoma, a rare phenomenon or common congenital predisposition?

Atypical hemolytic uremic syndrome (aHUS) is a complement-mediated thrombotic microangiopathy sometimes associated with germline variants in genes of the complement system. Clinical findings of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury arise due to aberrant complement protein activation in the circulation. A 13-month-old boy with metastatic neuroblastoma (NB) developed aHUS during his first cycle of induction chemotherapy with germline testing revealing a complement factor H (CFH) gene mutation, currently classified as a variant of uncertain significance (VUS). Now he is in disease remission after successful complement blockade therapy, thus highlighting a unique presentation of aHUS in a patient with newly diagnosed NB.

Delving into the clinical impact of NETs in pediatric cancer

Pediatric cancer, a complex and heterogeneous group of diseases, continues to challenge medical research and treatment strategies. Despite advances in precision medicine and immunotherapy, certain aggressive subtypes of pediatric cancer are resistant to conventional therapies, requiring further exploration of potential therapeutic targets. Neutrophil extracellular traps (NETs), net-like structures released by neutrophils, have emerged as a potential player in the pediatric cancer landscape. However, our understanding of their role in pediatric oncology remains limited. This systematic review examines the current state of the NETs literature in pediatric cancer, focusing on the most frequent subtypes. The review reveals the scarcity of research in this area, highlighting the need for further investigation. The few studies available suggest that NETs may influence infection risk, treatment resistance and prognosis in certain pediatric malignancies. Although the field is still in its infancy, it holds great promise for advancing our understanding of pediatric cancer biology and potential therapeutic pathways. IMPACT: This review identifies a significant gap in research on neutrophil extracellular traps (NETs) in pediatric cancer. It provides a summary of existing studies and their promising findings and potential, as well as a comprehensive overview of current research on NETs in certain tumor types. It also emphasizes the lack of specific studies in pediatric cancer. The review encourages the prioritization of NET research in pediatric oncology, with the aim of improving prognosis and developing new treatments through increased understanding and targeted studies.

Transplant-associated thrombotic microangiopathy in pediatrics: incidence, risk factors, therapeutic options, and outcome based on data from a single center

Background

Transplant-associated thrombotic microangiopathy (TA-TMA) is a critical complication of hematopoietic stem cell transplantation. Awareness about TA-TMA has increased in recent years, resulting in the implementation of TA-TMA screening in most centers.

Methods

Retrospective analysis of children who underwent autologous or allogeneic hematopoietic stem cell transplantation at our center between January 2018 and December 2022 was conducted to evaluate the incidence, clinical features, and outcomes of TA-TMA following the administration of different therapeutic options.

Results

A total of 45 patients comprised the study cohort, of whom 10 developed TA-TMA with a cumulative incidence of 22% by 100 days after transplantation. Patients with and without TA-TMA in our cohort displayed an overall survival of 80% and 88%, respectively (p = 0.48), and a non-relapse mortality of 0% and 5.7%, respectively (p = 0.12), at 1 year after transplantation. Risk factors for TA-TMA development included allogeneic transplantation and total body irradiation-based conditioning regime. Among the 10 patients with TA-TMA, 7 did not meet the high-risk criteria described by Jodele and colleagues. Of these seven patients, two responded to calcineurin-inhibitor withdrawal without further therapy and five developed multiorgan dysfunction syndrome and were treated with anti-inflammatory steroids (prednisone), and all responded to therapy. The three patients with high-risk TA-TMA were treated with complement blockade or prednisone, and all responded to therapy.

Conclusion

TA-TMA is a multifactorial complication with high morbidity rates. Patients with high-risk TA-TMA may benefit from complement blockade using eculizumab. No consensus has been reached regarding therapy for patients who do not meet high-risk criteria. Our analysis showed that these patients may respond to anti-inflammatory treatment with prednisone.

Excessive cleavage of von Willebrand factor multimers by ADAMTS13 may predict the progression of transplant-associated thrombotic microangiopathy

Background

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.

Objectives

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.

Methods

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.

Results

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.

Conclusion

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.

Eculizumab for Shiga-toxin-induced hemolytic uremic syndrome in adults with neurological involvement

The role of eculizumab in treating Shiga-toxin-producing Escherichia coli (STEC) hemolytic uremic syndrome (HUS) patients with neurological involvement remains unclear. We describe two distinctly different STEC-HUS patients with neurologic involvement successfully managed with eculizumab, and perform a literature review of all published cases. Both patients had complete resolution of neurological symptoms after initiation of eculizumab. Eighty patients with STEC-HUS treated with eculizumab were identified in the literature, 68.7% had complete resolution of neurological symptoms. Based on our experience and literature review, three prevailing themes were noted: 1) Early eculizumab administration optimized neurological outcomes, 2) Symptom resolution may not be immediate, neurological symptoms may initially worsen before improvement, and 3) Plasma exchange yielded no benefit. Early administration of eculizumab may reverse neurotoxicity in patients with STEC-HUS.

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.

Systemic inflammatory autoimmune disease before allogeneic hematopoietic stem cell transplantation is a risk factor for death in patients with myelodysplastic syndrome or chronic myelomonocytic leukemia

Myelodysplastic syndrome (MDS) is well known to be complicated by systemic inflammatory autoimmune disease (SIADs). However, it remains unclear how the prognosis after allogenic hematopoietic stem cell transplantation (allo-HSCT) in patients with MDS is impacted by SIADs that occur before allo-HSCT. Therefore, we hypothesized that SIADs before allo-HSCT may be a risk factor for negative outcomes after allo-HSCT in patients with MDS. We conducted a single-center, retrospective, observational study of sixty-nine patients with MDS or chronic myelomonocytic leukemia who underwent their first allo-HCT. Fourteen of the patients had SIADs before allo-HSCT. In multivariate analysis, the presence of SIADs before allo-HSCT was an independent risk factor for overall survival (HR, 3.36, 95% confidence interval: 1.34-8.42, p = 0.009). Endothelial dysfunction syndrome was identified in five of 14 patients with SIADs who required immunosuppressive therapy or intensive chemotherapy, and notably, all patients with uncontrollable SIADs at allo-HSCT developed serious endothelial dysfunction syndrome and died in the early phase after allo-HSCT. The development of SIADs in the context of MDS is thought to reflect the degree of dysfunction of hematopoietic cells in MDS and suggests a higher risk of disease progression. In addition, MDS patients with SIADs before allo-HSCT are considered to be at higher risk of endothelial dysfunction syndrome because of preexisting vascular endothelial dysfunction due to SIADs. In conclusion, SIADs before allo-HSCT constitute an independent risk factor for death in MDS patients undergoing allo-HSCT.

Cystatin C Outperforms Creatinine in Predicting Cefepime Clearance in Pediatric Stem Cell Transplant Recipients

Pediatric hematopoietic stem cell transplant (HSCT) patients are at risk of developing both sepsis and altered kidney function. Cefepime is used for empiric coverage post-HSCT and requires dose adjustment based on kidney function. Since cefepime's antimicrobial efficacy is determined by the time free concentrations exceed bacterial minimum inhibitory concentration (MIC), it is important to assess kidney function accurately to ensure adequate concentrations. Serum creatinine (SCr) is routinely used to estimate glomerular filtration rate (eGFR) but varies with muscle mass, which can be significantly lower in HSCT patients, making SCr an inaccurate kidney function biomarker. Cystatin C (CysC) eGFR is independent of muscle mass, though steroid use increases CysC. Objectives of this study were to describe how eGFR impacts cefepime pharmacokinetic/pharmacodynamic (PK/PD) target attainment in pediatric HSCT patients, to investigate which method of estimating GFR (SCr, CysC, combined) best predicts cefepime clearance, and to explore additional predictors of cefepime clearance. Patients admitted to the pediatric HSCT unit who received ≥2 cefepime doses were prospectively enrolled. We measured total cefepime peak/trough concentrations between the second and fourth cefepime doses and measured SCr and CysC if not already obtained clinically within 24h of cefepime samples. eGFRs were calculated with Chronic Kidney Disease in Children U25 equations. Bayesian estimates of cefepime clearance were determined with a pediatric cefepime PK model and PK software MwPharm++. Simple linear regression was used to compare cefepime clearance normalized to body surface area (BSA) to BSA-normalized SCr-, CysC-, and SCr-/CysC-eGFRs, while multiple linear regression was used to account for additional predictors of cefepime clearance. For target attainment, we assessed the percentage of time free cefepime concentrations exceeded 1x MIC (%fT>1x MIC) and 4x MIC (%fT>4x MIC) using a susceptibility breakpoint of 8 mg/L for Pseudomonas aeruginosa. We enrolled 53 patients (ages 1 to 30 years, median 8.9 years). SCr- and CysC-eGFRs were lower in patients who attained 100% fT>1xMIC compared to those who did not attain this target: 115 versus 156 mL/min/1.73m2 (p = .01) for SCr-eGFR and 73.5 versus 107 mL/min/1.73m2 (p < .001) for CysC-eGFR. SCr-eGFR was weakly positively correlated with cefepime clearance (adjusted [a]r2= 0.14), while CysC-eGFR and SCr-/CysC-eGFR had stronger positive correlations (ar2 = 0.30 CysC, ar2 = 0.28 combo. There was a weak, significant linear association between increasing CysC-eGFR and decreased %fT>1xMIC (ar2 = 0.32) and %fT>4xMIC (ar2 = 0.14). No patients with a CysC-eGFR >120 mL/min/1.73 m2 achieved 100% fT>1xMIC or 50% fT>4x MIC. In multiple regression models, underlying diagnosis of hemoglobinopathy (in all models) and being pretransplant (in SCr and combined models) were associated with increased cefepime clearance, while concomitant use of calcineurin inhibitors was associated with decreased cefepime clearance in all models. Overall, the combo-eGFR model with timing pretransplant, hemoglobinopathy, and use of calcineurin inhibitors had the best performance (ar2 = 0.63). CysC-based eGFRs (CysC alone and combined) predicted cefepime clearance better than SCr-eGFR, even after considering steroid use. Increasing CysC eGFR correlated with decreased probability of PD target attainment, raising concerns for underdosing at high eGFRs. CysC should be included when estimating kidney function to provide adequate dosing of cefepime in pediatric HSCT patients.

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.

Thrombotic Microangiopathy After Hematopoietic Stem Cell and Solid Organ Transplantation: A Review for Intensive Care Physicians

Intensive care physicians may assume the primary care of patients with transplant-associated thrombotic microangiopathy (TA-TMA), an uncommon but potentially critical complication of hematopoietic stem cell transplants (HSCTs) and solid organ transplants. TA-TMA can have a dramatic presentation with multiple organ dysfunction syndrome (MODS) associated with high morbidity and mortality. The typical presenting clinical features are hemolytic anemia, thrombocytopenia, refractory hypertension, proteinuria and worsening renal failure. Intestinal involvement, with abdominal pain, nausea and vomiting, gastrointestinal bleeding, and ascites are also common. Cardiopulmonary involvement may develop from various causes including pulmonary arteriolar hypertension, pleural and pericardial effusions, and diffuse alveolar hemorrhage. Due to other often concurrent complications after HSCT, early diagnosis and effective management of TA-TMA may be challenging. Close collaboration between ICU and transplant physicians, along with other relevant specialists, is needed to best manage these patients. There are currently no approved therapies for the treatment of TA-TMA. Plasma exchange and rituximab are not recommended unless circulating factor H (CFH) antibodies or thrombotic thrombocytopenic purpura (TTP; ADAMTS activity < 10%) are diagnosed or highly suspected. The role of the complement pathway activation in the pathophysiology of TA-TMA has led to the successful use of targeted complement inhibitors, such as eculizumab. However, the relatively larger studies using eculizumab have been mostly conducted in the pediatric population with limited data on the adult population. This review is focused on the role of intensive care physicians to emphasize the clinical approach to patients with suspected TA-TMA and to discuss diagnosis and treatment strategies.

Effects of CYP3A5 Genotype on Tacrolimus Pharmacokinetics and Graft-versus-Host Disease Incidence in Allogeneic Hematopoietic Stem Cell Transplantation

Tacrolimus (Tac) is pivotal in preventing acute graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (alloHSCT). It has been reported that genetic factors, including CYP3A5*3 and CYP3A4*22 polymorphisms, have an impact on Tac metabolism, dose requirement, and response to Tac. There is limited information regarding this topic in alloHSCT. The CYP3A5 genotype and a low Tac trough concentration/dose ratio (Tac C0/D ratio) can be used to identify fast metabolizers and predict the required Tac dose to achieve target concentrations earlier. We examined 62 Caucasian alloHSCT recipients with a fast metabolizer phenotype (C0/dose ratio ≤ 1.5 ng/mL/mg), assessing CYP3A5 genotypes and acute GVHD incidence. Forty-nine patients (79%) were poor metabolizers (2 copies of the variant *3 allele) and 13 (21%) were CYP3A5 expressers (CYP3A5*1/*1 or CYP3A5*1/*3 genotypes). CYP3A5 expressers had lower C0 at 48 h (3.7 vs. 6.2 ng/mL, p = 0.03) and at 7 days (8.6 vs. 11.4 ng/mL, p = 0.04) after Tac initiation, tended to take longer to reach Tac therapeutic range (11.8 vs. 8.9 days, p = 0.16), and had higher incidence of both global (92.3% vs. 38.8%, p < 0.001) and grade II-IV acute GVHD (61.5% vs. 24.5%, p = 0.008). These results support the adoption of preemptive pharmacogenetic testing to better predict individual Tac initial dose, helping to achieve the therapeutic range and reducing the risk of acute GVHD earlier.

Antiviral cellular therapy for enhancing T-cell reconstitution before or after hematopoietic stem cell transplantation (ACES): a two-arm, open label phase II interventional trial of pediatric patients with risk factor assessment

Viral infections remain a major risk in immunocompromised pediatric patients, and virus-specific T cell (VST) therapy has been successful for treatment of refractory viral infections in prior studies. We performed a phase II multicenter study (NCT03475212) for the treatment of pediatric patients with inborn errors of immunity and/or post allogeneic hematopoietic stem cell transplant with refractory viral infections using partially-HLA matched VSTs targeting cytomegalovirus, Epstein-Barr virus, or adenovirus. Primary endpoints were feasibility, safety, and clinical responses (>1 log reduction in viremia at 28 days). Secondary endpoints were reconstitution of antiviral immunity and persistence of the infused VSTs. Suitable VST products were identified for 75 of 77 clinical queries. Clinical responses were achieved in 29 of 47 (62%) of patients post-HSCT including 73% of patients evaluable at 1-month post-infusion, meeting the primary efficacy endpoint (>52%). Secondary graft rejection occurred in one child following VST infusion as described in a companion article. Corticosteroids, graft-versus-host disease, transplant-associated thrombotic microangiopathy, and eculizumab treatment correlated with poor response, while uptrending absolute lymphocyte and CD8 T cell counts correlated with good response. This study highlights key clinical factors that impact response to VSTs and demonstrates the feasibility and efficacy of this therapy in pediatric HSCT.

Isolated massive pleural effusion as a manifestation of chronic graft versus host disease successfully treated with corticosteroid

Isolated pleural effusion is a rare manifestation of chronic graft versus host disease (cGVHD) after hematopoietic stem cell transplantation (HSCT). We herein report a 58-year-old woman presenting with massive pleural effusion approximately 1 year after allogeneic HSCT, who was successfully treated with corticosteroid. She had discontinued tacrolimus approximately 1 month before she presented with pleural effusion, which was attributed to cGVHD after a thorough exclusion process. This case illustrates a unique manifestation of atypical cGVHD and highlights the need for prompt therapy initiation.

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.

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.

Efficacy and Safety of a DOAC Compared to Unfractionated Heparin and A Low Molecular Weight Heparin in the Prevention of Thromboembolism in Hematopoietic Stem Cell Transplant Recipients

Background

Hematopoietic stem cell transplantation (HSCT) patients are at risk of thromboembolic events, making thromboprophylaxis crucial.

Objectives

This study aimed to compare apixaban, a direct factor Xa inhibitor (DOAC), with dalteparin and unfractionated heparin for thromboprophylaxis in HSCT recipients. The safety outcome included the assessment of hemorrhagic events.

Methods

In this open-label randomized clinical trial, 182 HSCT recipients were divided into three groups: Apixaban (n = 61, 2.5 mg two times a day), dalteparin (n = 59, 5000 IU daily), and unfractionated heparin (n = 62, 5000 IU twice daily). These anticoagulant regimens were administered after central vein catheterization and during hospitalization. The primary clinical outcome was the risk of thrombosis, and the secondary outcome was the rate of bleeding. Relevant laboratory results were analyzed using appropriate statistical tests.

Results

Among the 61 patients in the apixaban group, six experienced thrombosis (9.83%), with four (6.65%) of them on anticoagulants. In the dalteparin group, three patients (5%) developed thrombosis, two of whom (3.38%) were on anticoagulants. In the heparin group, all four thrombosis cases (6.4%) occurred in patients on anticoagulants (P = 0.543 overall and P = 0.776 in anticoagulant users). Only two cases of bleeding were reported (1.09% overall), one in the dalteparin group (1.69%) and the other in the apixaban group (1.63%).

Conclusions

Apixaban, dalteparin, and heparin demonstrated similar effectiveness in preventing thromboembolism in HSCT recipients. Furthermore, the comparison of bleeding rates across the study groups did not reveal significant differences. Larger studies with higher event rates may yield more precise conclusions.

Incidence and Role of Recipient-Specific Antibodies in Allogeneic Hematopoietic Cell Transplantation from Mismatched Related Donors

High titer of donor-specific antibodies (DSAs) increases the risk of graft rejection after mismatched related hematopoietic cell transplantation (HCT). There are no data regarding the incidence of anti-HLA recipient-specific antibodies (RSAs) and their role after transplantation. Here we aimed to identify the incidence of RSAs in a mismatched related hematopoietic cell donor population and their possible impact on immune-mediated complications, such as acute graft-versus-host disease (aGVHD), and complications resulting from endothelial injury, such as transplantation-associated thrombotic microangiopathy (TA-TMA) and veno-occlusive disease (VOD). We prospectively analyzed the incidence of anti-HLA antibodies in 28 mismatched related pairs of recipients and their donors who underwent HCT at our center between 2020 and 2022. In positive samples screened for anti-HLA class I and/or II antibodies, the specificity of the HLA antibodies was analyzed. All recipients had a hematologic malignancy and received a myeloablative conditioning regimen and immunosuppression consisting of post-transplantation cyclophosphamide, tacrolimus, and mycophenolate mofetil. Patients were tested for TA-TMA and aGVHD development during routine post-transplantation visits up to 100 days post-transplantation. We used modified Jodele criteria for TA-TMA diagnosis, and based aGVHD grading on the MAGIC criteria. VOD was assessed using the European Society for Blood and Marrow Transplantation. Anti-HLA antibodies were detected in 12 donors (43%) and in 9 recipients (32%). There were no significant differences between donors and recipients according to age (median, 42 years [range, 17 to 69 years] versus 39 years [range, 8 to 68 years]), sex, or pregnancy history. No transfusion history was noted in the donor group (P < .05). RSA antibodies were present more often than DSAs and were detected in 9 out of 12 (75%) anti-HLA-positive donors and in only 2 out of 9 (22%) recipients, respectively (P < .05). During the follow-up, 11 patients (39%) developed aGVHD, including grade I-II in 9 (32%) and grade III-IV in 2 (7%). Twelve patients (43%) met the criteria for TA-TMA, and only 1 patient (3.5%) was diagnosed with VOD by day 100 post-HCT. RSAs were detected significantly more often in the TA-TMA group; among 12 patients diagnosed with TA-TMA, 7 (58%) had RSAs (P < .05). We did not find a correlation between RSAs and aGVHD. The patient with VOD did not have an RSA-positive donor. There was no difference in membrane attack complex (MAC) concentration in the RSA-positive group on day 30 and day 60 post-HCT; however, there was a trend toward higher MAC concentration in the RSA-positive group on day 100 (median, 912 ng/mL [range, 788 to 1120 ng/mL] versus 616 ng/mL [range, 352 to 1244 ng/mL]; P = .055). Patients with RSA suffered more often from platelet and red blood cell decreases or transfusion refractoriness, and increased lactate dehydrogenase activity was observed in all RSA-positive cases. The donor immune status and the presence of RSA may be associated with higher rates of TA-TMA in mismatched HCT recipients. Antibody-mediated complement activation might be an additional factor influencing TA-TMA occurrence.

Where have all the platelets gone? HIT, DIC, or something else?

Thrombocytopenia in ill children is common; accurately diagnosing the underlying etiology is challenging and essential for appropriate management. Triggers for accelerated consumption of platelets are numerous; common downstream mechanisms of clearance include platelet trapping in microvascular thrombi, phagocytosis, and platelet activation. Thrombocytopenia with microangiopathic hemolytic anemia (MAHA) is frequently due to disseminated intravascular coagulation. Thrombotic microangiopathy (TMA) is a subgroup of MAHA. Specific TMA syndromes include thrombotic thrombocytopenic purpura, complement-mediated TMA (CM-TMA), and Shiga toxin-mediated hemolytic uremic syndrome. Isolated thrombocytopenia is characteristic of immune thrombocytopenia; however, concomitant cytopenias are frequent in critically ill patients, making the diagnosis difficult. Immune thrombocytopenia with large vessel thrombosis is a feature of heparin-induced thrombocytopenia and antiphospholipid antibody syndrome. In addition, thrombocytopenia is common with macrophage activation, which is characteristic of hemophagocytic lymphohistiocytosis. While thrombocytopenia in ill patients can be driven by hypoproliferative processes such as myelosuppression and/or bone marrow failure, this review will focus on consumptive thrombocytopenia due to immune and nonimmune causes.

Diagnosis and management of endothelial disorders following haematopoietic stem cell transplantation

Haematopoietic stem cell transplantation is a mainstay of therapy for numerous malignant and nonmalignant diseases. Endothelial activation and dysfunction occur after stem cell transplantation, driven by various patient- and transplant-specific factors. This can manifest as one of the relatively uncommon endothelial injury syndromes, such as sinusoidal obstruction syndrome, transplant-associated thrombotic microangiopathy, idiopathic pneumonia syndrome, capillary leak syndrome, engraftment syndrome or posterior reversible encephalopathy syndrome. This review focuses on the pathogenesis, classification and diagnosis of these disorders, as well as provides guidance on risk mitigation and treatment.

Increased Body Mass Index Augments Endothelial Injury and Clinical Outcomes after Hematopoietic Stem Cell Transplantation

Higher body mass index (BMI) is characterized as a chronic inflammatory state with endothelial dysfunction. Endothelial injury after allogeneic hematopoietic stem cell transplantation (allo-HSCT) puts patients at risk for such complications as transplantation-associated thrombotic microangiopathy (TA-TMA) and acute graft-versus-host-disease (aGVHD). To evaluate the impact of increased BMI on endothelial injury after allo-HSCT in pediatric and young adult patients, we conducted a retrospective cohort study evaluating 476 consecutive allo-HSCT children and young adult recipients age 0 to 20 years. Our analysis was subdivided based on distinct age categories (<2 years and 2 to 20 years). BMI was considered as a variable but was also expressed in standard deviations from the mean adjusted for age and sex (z-score), based on established criteria from the World Health Organization (age <2 years) and the Centers for Disease Control and Prevention (age 2 to 20 years) to account for differences associated with age. Primary endpoints included the incidences of TA-TMA and aGVHD. Increased BMI z-score was associated with TA-TMA after allo-HSCT in patients age <2 years (median, 18.1; IQR, 17 to 20; P = .006) and in patients age 2 to 20 years (median, 18.7; IQR, 16 to 21.9; P = .02). Higher BMI z-score correlated with TA-TMA risk in both age groups, with a BMI z-score of .9 in the younger cohort and .7 (IQR, -.4 to 1.6; P = .04) in the older cohort. Increased BMI z-score was associated with an increased risk of TA-TMA in a multivariate analysis of the entire cohort (odds ratio [OR], 1.2; 95% confidence interval [CI], 1.05 to 1.37; P = .008). Multivariate analysis also demonstrated that patients with BMI in the 85th percentile or greater had an increased risk of developing TA-TMA compared to those with a lower BMI percentile (OR, 2.66; 95% CI, 1.62 to 4.32; P < .001). Baseline and day +7 ST2 levels were elevated in subjects with TA-TMA compared to those without TA-TMA in both age groups. Baseline sC5b-9 concentration was not correlated with BMI z-score, but sC5b-9 concentration was increased markedly by 7 days post-allo-HSCT in patients age <2 years who later developed TA-TMA compared to those who never developed TA-TMA (P = .001). The median BMI z-score was higher for patients with aGVHD compared to patients without aGVHD (.7 [range, -3.9 to 3.9] versus .2 [range, -7.8 to 5.4]; P = .03). We show that high BMI is associated with augmented risk of endothelial injury after HSCT, specifically TA-TMA. These data identify a high-risk population likely to benefit from early interventions to prevent endothelial injury and prompt treatment of established endothelial injury.

Beyond Immunosuppression: The Intricate Relationship Between Tacrolimus and Microangiopathy

Tacrolimus, widely known as Prograf, has become the preferred immunosuppressant for preventing graft rejection in solid organ transplant recipients, particularly in steroid-sparing regimens. Its efficacy and reduced risk of acute and chronic rejection compared to cyclosporine have made it the preferred treatment option for transplant patients. However, tacrolimus has drawbacks as it is associated with adverse effects, such as renal tubular necrosis, kidney failure, hypertension, metabolic acidosis, and new-onset diabetes mellitus. Among the less common but potentially severe complications is thrombotic microangiopathy linked to tacrolimus usage. Identifying and addressing this condition early on is crucial given its severity and potential complications. Manifestations of this microangiopathy can vary, encompassing renal, neurological, cardiac, and respiratory symptoms, and, in some cases, presenting as pancreatitis, intestinal ischemia, or skin abnormalities. Although conventional management often involves plasma exchange as the primary therapeutic option, recent insights into the pathophysiology have led to newer drugs, such as eculizumab and belatacept, offering promising outcomes. In this narrative review, we delve deeper into the underlying pathophysiological mechanisms of tacrolimus-induced thrombotic microangiopathy and aim to provide clinicians with valuable recommendations for efficient and timely treatment strategies. By understanding the complexities of this condition and staying abreast of the latest advancements in therapeutic options, healthcare providers can optimize patient outcomes and ensure safer tacrolimus administration in solid organ transplant recipients.

Prospective Clinical and Biomarker Validation of the American Society for Transplantation and Cellular Therapy Consensus Definition for Transplantation-Associated Thrombotic Microangiopathy

Transplantation-associated thrombotic microangiography (TA-TMA) is a disorder that causes severe complications after allogeneic hematopoietic cell transplantation (allo-HCT). Diagnosing TA-TMA is challenging because of the lack of standardized criteria. In this study, we aimed to evaluate the new TA-TMA consensus definition from the American Society for Transplantation and Cellular Therapy (ASTCT) panel as part of an ongoing prospective pediatric cohort study, and also to compare the impact and outcomes of using the current definition of clinical TMA (cTMA) versus the new consensus definition. We included patients age 0 to 18 years who underwent their first allo-HCT between May 2021 and January 2023 at Texas Children's Hospital. We compared the incidence, biomarkers, and outcomes of TA-TMA applying the previous and recently proposed screening algorithms and definitions. Whereas use of the classic microangiopathic hemolytic anemia (MAHA)-based cTMA definition led to an incidence of 12.7% by day 100 post-transplantation, the ASTCT-HR definition doubled the incidence to 28.5% by day 100. In contrast to patients with a concordant diagnosis (+/+), who had significantly worse post-transplantation survival, those reclassified as TA-TMA only by the new definition (-/+) had a significantly different prognosis (100% survival at day 100) despite the lack of TMA-directed therapy. Furthermore, biomarkers of the terminal and alternative complement pathways (sC5b9 and Ba, respectively) were significantly elevated compared with non-TMA patients around day 15 in the concordant group (+/+) but not in the discordant group (-/+). The recently proposed ASTCT consensus TA-TMA diagnosis is more sensitive and allows earlier recognition of manifestation that requires closer clinical monitoring but risks overdiagnosis and overtreatment. We recommend additional prospective validation.

Systemic complement activation influences outcomes after allogeneic hematopoietic cell transplantation: A prospective French multicenter trial

Complement activation has shown a role in murine models of graft-versus-host disease (GVHD) and in endothelial complications after allogeneic hematopoietic cell transplantation (allo-HSCT). However, its impact on post-transplant outcomes has not been so far fully elucidated. Here, we conducted a prospective multicentric trial (NCT01520623) performing serial measurements of complement proteins, regulators, and CH50 activity for 12 weeks after allo-HSCT in 85 patients receiving a myeloablative conditioning (MAC) regimen for various hematological malignancies. Twenty-six out of 85 patients showed an "activated" complement profile through the classical/lectin pathway, defined as a post-transplant decline of C3/C4 and CH50 activity. Time-dependent Cox regression models demonstrated that complement activation within the first weeks after allo-HSCT was associated with increased non-relapse mortality (hazard ratio [HR]: 3.69, 95% confident interval [CI]: 1.55-8.78, p = .003) and poorer overall survival (HR: 2.72, 95% CI: 1.37-5.39, p = .004) due to increased incidence of grade II-IV acute GVHD and in particular gastrointestinal (GI) GVHD (HR: 36.8, 95% CI: 12.4-109.1, p < .001), higher incidences of thrombotic microangiopathy (HR: 8.58, 95% CI: 2.16-34.08, p = .0022), capillary leak syndrome (HR: 7.36, 95% CI: 2.51-21.66, p = .00028), post-engraftment bacterial infections (HR: 2.37, 95% CI: 1.22-4.63, p = .0108), and EBV reactivation (HR: 3.33, 95% CI: 1.31-8.45, p = .0112). Through specific immune staining, we showed the correlation of deposition of C1q, C3d, C4d, and of C5b9 components on endothelial cells in GI GVHD lesions with the histological grade of GVHD. Altogether these findings define the epidemiology and the clinical impact of complement classical/lectin pathway activation after MAC regimens and provide a rational for the use of complement inhibitory therapeutics in a post-allo-HSCT setting.

Rare variants in complement system genes associate with endothelial damage after pediatric allogeneic hematopoietic stem cell transplantation

Introduction

Complement system has a postulated role in endothelial problems after hematopoietic stem cell transplantation (HSCT). In this retrospective, singlecenter study we studied genetic complement system variants in patients with documented endotheliopathy. In our previous study among pediatric patients with an allogeneic HSCT (2001-2013) at the Helsinki University Children´s Hospital, Finland, we identified a total of 19/122 (15.6%) patients with vascular complications, fulfilling the criteria of capillary leak syndrome (CLS), venoocclusive disease/sinusoidal obstruction syndrome (VOD/SOS) or thrombotic microangiopathy (TMA).

Methods

We performed whole exome sequencing (WES) on 109 patients having an adequate pre-transplantation DNA for the analysis to define possible variations and mutations potentially predisposing to functional abnormalities of the complement system. In our data analysis, we focused on 41 genes coding for complement components.

Results

50 patients (45.9%) had one or several, nonsynonymous, rare germline variants in complement genes. 21/66 (31.8%) of the variants were in the terminal pathway. Patients with endotheliopathy had variants in different complement genes: in the terminal pathway (C6 and C9), lectin pathway (MASP1) and receptor ITGAM (CD11b, part of CR3). Four had the same rare missense variant (rs183125896; Thr279Ala) in the C9 gene. Two of these patients were diagnosed with endotheliopathy and one with capillary leak syndrome-like problems. The C9 variant Thr279Ala has no previously known disease associations and is classified by the ACMG guidelines as a variant of uncertain significance (VUS). We conducted a gene burden test with gnomAD Finnish (fin) as the reference population. Complement gene variants seen in our patient population were investigated and Total Frequency Testing (TFT) was used for execution of burden tests. The gene variants seen in our patients with endotheliopathy were all significantly (FDR < 0.05) enriched compared to gnomAD. Overall, 14/25 genes coding for components of the complement system had an increased burden of missense variants among the patients when compared to the gnomAD Finnish population (N=10 816).

Discussion

Injury to the vascular endothelium is relatively common after HSCT with different phenotypic appearances suggesting yet unidentified underlying mechanisms. Variants in complement components may be related to endotheliopathy and poor prognosis in these patients.

Potential factors for and the prognostic impact of ascites after allogeneic hematopoietic stem cell transplantation

Ascites is sometimes detected after allogeneic hematopoietic stem cell transplantation (allo-HSCT); however, since limited information is currently available, its clinical meaning remains unclear. Therefore, we herein examined potential factors for and the impact of ascites on the prognosis of patients after allo-HSCT at our institutes. Fifty-eight patients developed ascites within 90 days of allo-HSCT (small in 34 (16%), moderate-large in 24 (11%)). A multivariate analysis identified veno-occlusive disease/sinusoidal obstruction syndrome (p = 0.01) and myeloablative conditioning (p = 0.01) as significant potential factors for the development of small ascites. Thrombotic microangiopathy (TMA) (p < 0.01) was a significant potential factor for moderate-large ascites. The incidence of both small and moderate-large ascites correlated with lower overall survival (p = 0.03 for small ascites and p < 0.01 for moderate-large ascites) and higher non-relapse mortality rates (p = 0.03 for small ascites and p < 0.01 for moderate-large ascites). Lower OS and higher NRM rates correlated with the incidence of both small and moderate-large ascites. Further investigation is warranted to establish whether the clinical sign of ascites improves the diagnostic quality of TMA in a large-scale study.

Pathway-driven rare germline variants associated with transplant-associated thrombotic microangiopathy (TA-TMA)

The significance of rare germline mutations in transplant-associated thrombotic microangiopathy (TA-TMA) is not well studied. We performed a genetic association study in 100 adult TA-TMA patients vs. 98 post-transplant controls after matching by race, sex, and year. We focused on 5 pathways in complement, von Willebrand factor (VWF) function and related proteins, VWF clearance, ADAMTS13 function and related proteins, and endothelial activation (3641variants in 52 genes). In the primary analysis focused on 189 functional rare variants, no differential variant enrichment was observed in any of the pathways; specifically, 29 % TA-TMA and 33 % controls had at least 1 rare complement mutation. In the secondary analysis focused on 37 rare variants predicted to be pathogenic or likely pathogenic by ClinVar, Complement Database, or REVEL in-silico prediction tool, rare variants in the VWF clearance pathway were found to be significantly associated with TA-TMA (p = 0.008). On the gene level, LRP1 was the only one with significantly increased variants in TA-TMA in both analyses (p = 0.025 and 0.015). In conclusion, we did not find a significant association between rare variants in the complement pathway and TA-TMA; however, we discovered a new signal in the VWF clearance pathway driven by the gene LRP1 among likely pathogenic variants.

Endothelial cell provenance: an unclear role in transplant medicine

An understanding of the interplay between both donor endothelial progenitors and the recipient endothelium (in the case of hematopoietic cell transplant) and recipient endothelial provenance upon the established donor endothelium (in the case of solid organ transplant) is unknown. It is postulated that this interplay and consequences of purported dual endothelial populations may be a component of the post-transplant disease process and contribute to complications of engraftment or rejection. To address this potential confounding and often overlooked arena of vascular biology, a directed brief overview primarily focused on literature presented over the last decade is presented herein.

Pathological evaluation of renal complications in children following allogeneic hematopoietic stem cell transplantation: a retrospective cohort study

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is a curative therapy for hematologic malignancies and non-malignant disorders, such as aplastic anemia, fanconi anemia, and certain immune deficiencies. Post-transplantation kidney injury is a common complication and involves a wide spectrum of structural abnormalities, including glomerular (MSPGN, mesangial proliferative glomerulonephritis; FSGS, focal segmental glomerulosclerosis; MPGN, membranoproliferative glomerulonephritis; MCD, minimal change disease), vascular (TMA, thrombotic microangiopathy), and/or tubulointerstitial (TIN, tubulointerstitial nephritis; ATI, acute tubular injury). Renal biopsy is the gold-standard examination for defining multiple etiologies of kidney impairment. Although kidney injury following HSCT has been studied, little is known about the effects of allo-HSCT on renal pathology in pediatric patients.

METHODS

We retrospectively analyzed renal biopsy specimens from children with kidney injury after allo-HSCT and correlated results with clinical data in the last 10 years.

RESULTS

Among 25 children (18 males and 7 females), three patients had proteinuria indicating nephrotic syndrome (24-hour urinary total protein/weight > 50 mg/kg/d), nine patients had severely reduced estimated glomerular filtration rate (eGFR < 30 ml/min/1.73 m2) and four patients received kidney replacement therapy (KRT). The main pathologies identified from kidney biopsies were MSPGN (n = 12), FSGS (n = 12), MPGN (n = 5), TMA (n = 4), MCD (n = 3), diffuse glomerular fibrosis (DGF, n = 2), ATI and TIN, in isolation or combined with other pathologies. The median follow-up time was 16.5 (0.5 ~ 68.0) months. Three patients died of recurrent malignancy and/or severe infection, one child developed to end-stage renal disease (ESRD), six patients (24%) had elevated serum creatinine (SCr > 100µmol/l) and nine patients (36%) still had proteinuria.

CONCLUSIONS

This study evaluates histomorphologic findings from kidney biopsies of pediatric recipients following allo-HSCT. Detailed evaluation of renal biopsy samples is helpful to elucidate the nature of renal insult, and may potentially identify treatable disease processes.

Hematopoietic stem cell transplantation-associated thrombotic microangiopathy and the role of advanced practice providers and pharmacists

Hematopoietic stem cell transplantation-associated thrombotic microangiopathy (HSCT-TMA) is a severe and potentially life-threatening complication. HSCT-TMA is often underdiagnosed due to multifactorial pathophysiology and a historic lack of standard diagnostic criteria. Identification of the multi-hit hypothesis and the key role of the complement system, particularly the lectin pathway of complement, has led to development of treatments targeting the underlying pathogenesis of HSCT-TMA. Additional research is ongoing to investigate the efficacy and safety of these targeted therapies in patients with HSCT-TMA. Advanced practice providers (APPs; nurse practitioners and physician assistants) and pharmacists are critical members of the multidisciplinary HSCT team and ensure management of patients throughout the continuum of care. Additionally, pharmacists and APPs can improve patient care through medication management of complex regimens; transplant education for patients, staff, and trainees; evidence-based protocol and clinical guideline development; assessment and reporting of transplant-related outcomes; and quality improvement initiatives to improve outcomes. Understanding the presentation, prognosis, pathophysiology, and treatment options for HSCT-TMA can improve each of these efforts. Collaborative practice model for monitoring and care of HSCT-TMA. Advanced practice providers and pharmacists contribute to many aspects of patient care in transplant centers, including medication management for complex regimens; transplant education for patients, staff, and trainees; evidence-based protocol and clinical guideline development; assessment and reporting of transplant-related outcomes; and quality improvement initiatives. HSCT-TMA is a severe and potentially life-threatening complication that is often underdiagnosed. The collaboration of a multidisciplinary team of advanced practice providers, pharmacists, and physicians can optimize recognition, diagnosis, management, and monitoring of patients with HSCT-TMA, thereby improving outcomes for these patients.