Risk Factors for Transplant-Associated Thrombotic Microangiopathy after Autologous Hematopoietic Cell Transplant in High-Risk Neuroblastoma

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.

Genetic Susceptibility in Endothelial Injury Syndromes after Hematopoietic Cell Transplantation and Other Cellular Therapies: Climbing a Steep Hill

Hematopoietic stem cell transplantation (HSCT) remains a cornerstone in the management of patients with hematological malignancies. Endothelial injury syndromes, such as HSCT-associated thrombotic microangiopathy (HSCT-TMA), veno-occlusive disease/sinusoidal obstruction syndrome (SOS/VOD), and capillary leak syndrome (CLS), constitute complications after HSCT. Moreover, endothelial damage is prevalent after immunotherapy with chimeric antigen receptor-T (CAR-T) and can be manifested with cytokine release syndrome (CRS) or immune effector cell-associated neurotoxicity syndrome (ICANS). Our literature review aims to investigate the genetic susceptibility in endothelial injury syndromes after HSCT and CAR-T cell therapy. Variations in complement pathway- and endothelial function-related genes have been associated with the development of HSCT-TMA. In these genes, CFHR5, CFHR1, CFHR3, CFI, ADAMTS13, CFB, C3, C4, C5, and MASP1 are included. Thus, patients with these variations might have a predisposition to complement activation, which is also exaggerated by other factors (such as acute graft-versus-host disease, infections, and calcineurin inhibitors). Few studies have examined the genetic susceptibility to SOS/VOD syndrome, and the implicated genes include CFH, methylenetetrahydrofolate reductase, and heparinase. Finally, specific mutations have been associated with the onset of CRS (PFKFB4, CX3CR1) and ICANS (PPM1D, DNMT3A, TE2, ASXL1). More research is essential in this field to achieve better outcomes for our patients.

The Impact of 131I-Metaiodobenzylguanidine as a Conditioning Regimen of Tandem High-Dose Chemotherapy and Autologous Stem Cell Transplantation for High-Risk Neuroblastoma

BACKGROUND

The optimal conditioning regimen of tandem high-dose chemotherapy (HDC) and autologous stem cell transplantation (ASCT) for high-risk neuroblastoma (HR-NBL) has not been established. The efficacy of 131I-MIBG therapy is under exploration in newly diagnosed HR-NBL patients. Here, we compared the outcomes of tandem HDC/ASCT between the 131I-MIBG combination and non-MIBG groups.

METHODS

We retrospectively analyzed the clinical data of 33 HR-NBL patients who underwent tandem HDC/ASCT between 2007 and 2021 at the Seoul National University Children's Hospital.

RESULTS

The median age at diagnosis was 3.6 years. 131I-MIBG was administered to 13 (39.4%) of the patients. Thirty patients (90.9%) received maintenance therapy after tandem HDC/ASCT, twenty-two were treated with isotretinoin ± interleukin-2, and eight received salvage chemotherapy. The five-year overall survival (OS) and event-free survival (EFS) rates of all patients were 80.4% and 69.4%, respectively. Comparing the 131I-MIBG combined group and other groups, the five-year OS rates were 82.1% and 79.7% (p = 0.655), and the five-year EFS rates were 69.2% and 69.6% (p = 0.922), respectively. Among the adverse effects of grade 3 or 4, the incidence of liver enzyme elevation was significantly higher in the non-131I-MIBG group.

CONCLUSIONS

Although tandem HDC/ASCT showed promising outcomes, the 131I-MIBG combination did not improve survival rates.

Diffuse alveolar hemorrhage after hematopoietic cell transplantation- response to treatments and risk factors for mortality

Diffuse alveolar hemorrhage (DAH) is a life-threatening complication of hematopoietic cellular therapy (HCT). This study aimed to evaluate the effect of DAH treatments on outcomes using data from consecutive HCT patients clinically diagnosed with DAH from 3 institutions between January 2018-August 2022. Endpoints included sustained complete response (sCR) defined as bleeding cessation without recurrent bleeding, and non-relapse mortality (NRM). Forty children developed DAH at a median of 56.5 days post-HCT (range 1-760). Thirty-five (88%) had at least one concurrent endothelial disorder, including transplant-associated thrombotic microangiopathy (n=30), sinusoidal obstructive syndrome (n=19), or acute graft versus host disease (n=10). Fifty percent had a concurrent pulmonary infection at the time of DAH. Common treatments included steroids (n=17, 25% sCR), inhaled tranexamic acid (INH TXA,n=26, 48% sCR), and inhaled recombinant activated factor VII (INH fVIIa, n=10, 73% sCR). NRM was 56% 100 days after first pulmonary bleed and 70% at 1 year. Steroid treatment was associated with increased risk of NRM (HR 2.25 95% CI 1.07-4.71, p=0.03), while treatment with INH TXA (HR 0.43, 95% CI 0.19- 0.96, p=0.04) and INH fVIIa (HR 0.22, 95% CI 0.07-0.62, p=0.005) were associated with decreased risk of NRM. Prospective studies are warranted to validate these findings.

Systematic Review of Signs and Symptoms Associated with Hematopoietic Stem Cell Transplantation-Associated Thrombotic Microangiopathy

Hematopoietic stem cell transplantation-associated thrombotic microangiopathy (HSCT-TMA) is a serious complication of the transplantation process that has been consistently associated with substantially greater morbidity and mortality compared with HSCT recipients who do not develop TMA. This study aimed to systematically review published signs and symptoms of HSCT-TMA and compare patients with HSCT-TMA and HSCT recipients who do not develop TMA. Publications were identified using multiple search term variations for stem cell transplantation that were entered into the PubMed, Embase, and CINAHL databases. Two reviewers screened references at the abstract level before reviewing full texts against inclusion and exclusion criteria using a PICOS-T framework. Complication proportions were grouped by organ class and then by complication type. Meta-analyses were conducted using a random-effects model in RevMan 5.4. After 2338 references were screened, a total of 30 studies were included in our analyses. The majority of studies (n = 23; 14 adult, 5 pediatric, 4 both) examined allogeneic transplantations only. Four studies examined autologous transplantation only (all pediatric), and 3 studies included both transplantation types (all pediatric). HSCT-TMA was associated with renal dysfunction (odds ratio [OR], 11.04 for adult, allogeneic and 7.35 for pediatric, all transplantations), renal failure (OR, 2.41 for adult and pediatric, allogeneic), renal replacement therapy (OR, 6.99 for pediatric, all transplantations and 60.85 for adult, allogeneic), and hypertension (OR, 5.44 for adult, allogeneic). HSCT-TMA was associated with respiratory failure (OR, 8.00 for adult and pediatric, allogeneic), pulmonary hypertension (OR, 9.86 for adult and pediatric, allogeneic), need for pleurocentesis (OR, 5.45 for pediatric, all transplantations), noninvasive ventilation (OR, 6.15 for pediatric, all transplantations), and invasive mechanical ventilation (OR, 5.18 for pediatric, all transplantations). Additionally, HSCT-TMA was associated with neurologic symptoms (OR, 2.28 for adult and pediatric, allogeneic), pericardial effusion (OR, 2.56 for adult and pediatric, allogeneic and 8.76 for pediatric, all transplantations), liver injury (OR, 3.87 for adult, allogeneic), infection (OR, 9.25 for adult, allogeneic; 2.06 for pediatric, all transplantations), gastrointestinal (GI) bleeding (OR, 7.78 for adult and pediatric, allogeneic), and acute graft-versus-host disease grade III-IV (OR, 3.29 for adult and pediatric, allogeneic). This study represents the first systematic review of HSCT-TMA signs and symptoms. Current diagnostic criteria systems involve laboratory markers for multiorgan dysfunction, including renal dysfunction, liver injury, and general tissue damage. Diagnostic criteria include neurologic symptoms, increased need for transfusions, and hypertension. This study identified additional associations with HSCT-TMA, including increased pulmonary hypertension, respiratory failure, fever, GI bleeding, and pericardial effusion. These symptoms might be included for evaluation in future diagnostic criteria and current practice.

Haemolytic uraemic syndrome

Haemolytic uraemic syndrome (HUS) is a heterogeneous group of diseases that result in a common pathology, thrombotic microangiopathy, which is classically characterised by the triad of non-immune microangiopathic haemolytic anaemia, thrombocytopenia, and acute kidney injury. In this Seminar, different causes of HUS are discussed, the most common being Shiga toxin-producing Escherichia coli HUS. Identifying the underlying thrombotic microangiopathy trigger can be challenging but is imperative if patients are to receive personalised disease-specific treatment. The quintessential example is complement-mediated HUS, which once carried an extremely high mortality but is now treated with anti-complement therapies with excellent long-term outcomes. Unfortunately, the high cost of anti-complement therapies all but precludes their use in low-income countries. For many other forms of HUS, targeted therapies are yet to be identified.

To transplant, or not to transplant? That is the question. A patient advocate evaluation of autologous stem cell transplant in neuroblastoma

High-dose chemotherapy with autologous stem cell transplant (ASCT) has been a mainstay of high-risk neuroblastoma treatment for several decades, demonstrating improvements in event-free survival but with risks of serious or even life-threatening acute toxicities, severe long-term adverse health effects for survivors, and ongoing contention regarding overall survival benefit. The merits of ASCT in the modern era of immunotherapy are a source of debate among parents, advocates, and some physicians. Here we examine evidence for and against ASCT, explore parent attitudes and their turmoil over decision-making, and strongly encourage international research consortia to develop a coordinated strategy to accelerate progress toward a future that avoids the routine use of ASCT in high-risk neuroblastoma.

Massive periorbital edema following hematopoietic stem cell transplantation

Purpose

To describe a case of severe, bilateral periorbital edema after hematopoietic stem cell transplantation.

Observations

A three-year old girl with metastatic neuroblastoma underwent the second of two tandem autologous peripheral blood stem cell transplants, complicated by engraftment syndrome. On post-engraftment day 11, she developed acute onset of severe periorbital edema. She was soon thereafter diagnosed with transplant-associated thrombotic microangiopathy with significant volume overload requiring treatment with eculizumab and etanercept. Periorbital edema resolved after four days with concurrent treatment of her underlying condition.

Conclusions and Importance

We report an ocular manifestation related to complications of hematopoietic stem cell transplantation. This highlights a non-infectious etiology of eyelid swelling in the post-transplant, immunocompromised population.

Advancing therapy for neuroblastoma

Neuroblastomas are tumours of sympathetic origin, with a heterogeneous clinical course ranging from localized or spontaneously regressing to widely metastatic disease. Neuroblastomas recapitulate many of the features of sympathoadrenal development, which have been directly targeted to improve the survival outcomes in patients with high-risk disease. Over the past few decades, improvements in the 5-year survival of patients with metastatic neuroblastomas, from <20% to >50%, have resulted from clinical trials incorporating high-dose chemotherapy with autologous stem cell transplantation, differentiating agents and immunotherapy with anti-GD2 monoclonal antibodies. The next generation of trials are designed to improve the initial response rates in patients with high-risk neuroblastomas via the addition of immunotherapies, targeted therapies (such as ALK inhibitors) and radiopharmaceuticals to standard induction regimens. Other trials are focused on testing precision medicine strategies for patients with relapsed and/or refractory disease, enhancing the antitumour immune response and improving the effectiveness of maintenance regimens, in order to prolong disease remission. In this Review, we describe advances in delineating the pathogenesis of neuroblastoma and in identifying the drivers of high-risk disease. We then discuss how this knowledge has informed improvements in risk stratification, risk-adapted therapy and the development of novel therapies.

A pilot trial of prophylactic defibrotide to prevent serious thrombotic microangiopathy in high-risk pediatric patients

BACKGROUND

Transplant-associated thrombotic microangiopathy (TA-TMA) is an endothelial injury complication of hematopoietic stem cell transplant (HSCT) leading to end-organ damage and high morbidity and mortality. Defibrotide is an anti-inflammatory and antithrombotic agent that may protect the endothelium during conditioning.

PROCEDURE

We hypothesized that prophylactic use of defibrotide during HSCT conditioning and acute recovery could prevent TA-TMA. A pilot single-arm phase II trial (NCT#03384693) evaluated the safety and feasibility of administering prophylactic defibrotide to high-risk pediatric patients during HSCT and assessed if prophylactic defibrotide prevented TA-TMA compared to historic controls. Patients received defibrotide 6.25 mg/kg IV q6h the day prior to the start of conditioning through day +21. Patients were prospectively monitored for TA-TMA from admission through week 24 post transplant. Potential biomarkers of endothelial injury (suppression of tumorigenicity 2 [ST2], angiopoietin-2 [ANG-2], plasminogen activator inhibitor-1 [PAI-1], and free hemoglobin) were analyzed.

RESULTS

Twenty-five patients were enrolled, 14 undergoing tandem autologous HSCT for neuroblastoma and 11 undergoing allogeneic HSCT. Defibrotide was discontinued early due to possibly related clinically significant bleeding in 12% (3/25) of patients; no other severe adverse events occurred due to the study intervention. The other 22 patients missed a median of 0.7% of doses (0%-5.2%). One patient developed nonsevere TA-TMA 12 days post HSCT. This observed TA-TMA incidence of 4% was below the historic rate of 18%-40% in a similar population of allogeneic and autologous patients.

CONCLUSIONS

Our study provides evidence that defibrotide prophylaxis is feasible in pediatric patients undergoing HSCT at high risk for TA-TMA and preliminary data indicating that defibrotide may reduce the risk of TA-TMA.

Transplant-associated thrombotic microangiopathy: elucidating prevention strategies and identifying high-risk patients

INTRODUCTION

Hematopoietic stem cell transplantation-associated thrombotic microangiopathy (TA-TMA) is a severe complication of transplant. TA-TMA is a multifactorial disease where generalized endothelial dysfunction leads to microangiopathic hemolytic anemia, intravascular platelet activation, and formation of microthrombi leading to end-organ injury. It is essential to identify patients at risk for this complication and to implement early interventions to improve TA-TMA associated transplant outcomes.

AREAS COVERED

Recognition of TA-TMA and associated multi-organ injury, risk predictors, contributing factors, differential diagnosis and targeting complement pathway in TA-TMA by summarizing peer reviewed manuscripts.

EXPERT OPINION

TA-TMA is an important transplant complication. Diagnostic and risk criteria are established in children and young adults and risk-based targeted therapies have been proposed using complement blockers. The immediate goal is to extend this work into adult stem cell transplant recipients by implementing universal TA-TMA screening practices. This will facilitate early TA-TMA diagnosis and targeted interventions, which will further improve survival. While complement blocking therapy is effective, about one third of patients are refractory to treatment and those patients commonly die. The next hurdle for the field is identifying reasons for failure, optimizing strategies for complement modifying therapy and searching for additional targetable pathways of endothelial injury.

Transplant-associated thrombotic microangiopathy in pediatric patients: pre-HSCT risk stratification and prophylaxis

Transplant-associated thrombotic microangiopathy (TA-TMA) is an endothelial injury syndrome that complicates hematopoietic stem cell transplant (HSCT). Morbidity and mortality from TA-TMA remain high, making prevention critical. We describe our retrospective single-center experience of TA-TMA after pediatric allogeneic HSCT and present a novel pre-HSCT risk-stratification system and prophylaxis regimen. From January 2012 through October 2019, 257 patients underwent 292 allogeneic HSCTs. Prospective risk stratification was introduced in December 2016. High-risk (HR) patients were treated with combination prophylaxis with eicosapentaenoic acid and N-acetylcysteine. The 1-year cumulative incidence of TA-TMA was 6.3% (95% confidence interval [CI], 3.2-9.4). Age ≥10 years, myeloablative conditioning with total body irradiation, HLA mismatch, diagnosis of severe aplastic anemia or malignancy, prior calcineurin inhibitor exposure, and recipient cytomegalovirus seropositivity were found to be pre-HSCT risk factors for development of TA-TMA. Before routine prophylaxis, TA-TMA rates were significantly different between the HR and standard-risk groups, at 28.2% (95% CI, 0-12.7) vs 3.2% (0.1-6.3), respectively (P < .001). After introduction of prophylaxis, the 1-year cumulative incidence of TA-TMA in the HR group decreased to 4.5% (95% CI, 0-13.1; P = .062, compared with the incidence before prophylaxis). Multicenter pediatric studies are needed to validate these risk criteria and to confirm the efficacy of the prophylactic regimen.

A pragmatic multi-institutional approach to understanding transplant-associated thrombotic microangiopathy after stem cell transplant

Transplant-associated thrombotic microangiopathy (TA-TMA) is a severe complication of hematopoietic stem cell transplantation (HSCT). A single-center prospective screening study has shown that the incidence of TA-TMA is much higher than prior retrospective studies that did not systematically screen. These data have not been replicated in a multicenter study. Our objective was to determine the incidence and risk factors for TA-TMA and compare outcomes of pediatric HSCT patients with and without TA-TMA. Patients were prospectively screened for TA-TMA at participating centers using a simple to implement and inexpensive strategy from the start of the preparative regimen through day +100. TA-TMA was diagnosed if ≥4 of 7 laboratory/clinical markers diagnostic for TA-TMA were present concurrently or if tissue histology showed TA-TMA. A total of 614 patients (359 males; 58%) received prospective TA-TMA screening at 13 pediatric centers. TA-TMA was diagnosed in 98 patients (16%) at a median of 22 days (interquartile range, 14-44) posttransplant. Patients with TA-TMA had significantly increased bloodstream infections (38% [37/98] vs 21% [107/51], P ≤ .001), mean total hospitalization days (68; 95% confidence interval [CI], 63-74 vs 43; 95% CI, 41-45; P ≤ .001), and number of days spent in the intensive care unit (10.1; 95% CI, 6.4-14; vs 1.6; 95% CI, 1.1-2.2; P ≤ .001) in the first 100 days after HSCT compared with patients without TA-TMA. Overall survival was significantly higher in patients without TA-TMA (93%; 490/516) compared with patients with TA-TMA (78%; 76/98) (P ≤ .001). These data support the need for systematic screening for TA-TMA and demonstrate the feasibility and efficacy of an easy to implement strategy to do so.

Kidney Function after Treatment for Childhood Cancer: A Report from the St. Jude Lifetime Cohort Study

BACKGROUND

Survivors of childhood cancer may be at increased risk for treatment-related kidney dysfunction. Although associations with acute kidney toxicity are well described, evidence informing late kidney sequelae is less robust.

METHODS

To define the prevalence of and risk factors for impaired kidney function among adult survivors of childhood cancer who had been diagnosed ≥10 years earlier, we evaluated kidney function (eGFR and proteinuria). We abstracted information from medical records about exposure to chemotherapeutic agents, surgery, and radiation treatment and evaluated the latter as the percentage of the total kidney volume treated with ≥5 Gy (V5), ≥10 Gy (V10), ≥15 Gy (V15), and ≥20 Gy (V20). We also used multivariable logistic regression models to assess demographic and clinical factors associated with impaired kidney function and Elastic Net to perform model selection for outcomes of kidney function.

RESULTS

Of the 2753 survivors, 51.3% were men, and 82.5% were non-Hispanic White. Median age at diagnosis was 7.3 years (interquartile range [IQR], 3.3-13.2), and mean age was 31.4 years (IQR, 25.8-37.8) at evaluation. Time from diagnosis was 23.2 years (IQR, 17.6-29.7). Approximately 2.1% had stages 3-5 CKD. Older age at evaluation; grade ≥2 hypertension; increasing cumulative dose of ifosfamide, cisplatin, or carboplatin; treatment ever with a calcineurin inhibitor; and volume of kidney irradiated to ≥5 or ≥10 Gy increased the odds for stages 3-5 CKD. Nephrectomy was significantly associated with stages 3-5 CKD in models for V15 or V20.

CONCLUSIONS

We found that 2.1% of our cohort of childhood cancer survivors had stages 3-5 CKD. These data may inform screening guidelines and new protocol development.