• Proteinuria and elevated markers of complement activation at TMA diagnosis are associated with poor outcome.• Clinical interventions should be considered in HSCT patients with these high-risk features at the time TMA is diagnosed.Transplant-associated thrombotic microangiopathy (TMA) leads to generalized endothelial dysfunction that can progress to multiorgan injury, and severe cases are associated with poor outcomes after hematopoietic stem cell transplantation (HSCT). Identifying patients at highest risk for severe disease is challenging. We prospectively evaluated 100 consecutive HSCT recipients to determine the incidence of moderate and severe TMA and factors associated with poor overall outcomes. Thirty-nine subjects (39%) met previously published criteria for TMA. Subjects with TMA had a significantly higher nonrelapse mortality (43.6% vs 7.8%, P < .0001) at 1 year post-HSCT compared with those without TMA. Elevated lactate dehydrogenase, proteinuria on routine urinalysis, and hypertension were the earliest markers of TMA. Proteinuria (>30 mg/dL) and evidence of terminal complement activation (elevated sC5b-9) in the blood at the time of TMA diagnosis were associated with very poor survival (<20% at 1 year), whereas all TMA subjects without proteinuria and a normal sC5b-9 serum concentration survived (P < .01). Based on these prospective observations, we conclude that severe TMA occurred in 18% of HSCT recipients in our cohort and propose an algorithm to identify the highest-risk patients who might benefit from prompt clinical interventions. (Blood. 2014;124(4):645-653)

Overactivated complement is a high-risk feature in HSCT recipients with transplant associated thrombotic microangiopathy (TA-TMA), and untreated patients have dismal outcomes. We present our experience of 64 pediatric HSCT recipients with high risk TA-TMA and multi-organ injury treated with the complement blocker eculizumab. We demonstrate significant improvement in 1y post-HSCT survival to 66% in treated patients from our previously reported untreated cohort with same high-risk TA-TMA features that had 1y post-HSCT survival of 16.7%. Responding patients benefited from a brief but intensive eculizumab therapy course using PK/PD guided dosing, requiring a median of 11 doses of eculizumab (IQR 7-20). Therapy was discontinued due to resolution of TA-TMA at a median of 66 days (IQR 41-110). Subjects with higher complement activation measured by elevated blood sC5b-9 at the start of therapy were less likely to respond to treatment (OR =0.15, p-value 0.0014), and required more doses of eculizumab [r = 0.43, p-value = 0.0004]. Patients with intestinal bleeding had the fastest eculizumab clearance, required the highest number of eculizumab doses (20 vs 9, p=0.0015), and had lower 1y survival (44% vs 78%, p=0.01). Over 70% of survivors had proteinuria on long term follow up. The best GFR recovery in survivors was a median 20% lower (IQR 7.3-40.3%) than their pre-HSCT GFR. In summary, complement blockade with eculizumab is an effective therapeutic strategy for high risk TA-TMA, but some patients with severe disease lack a complete response, prompting us to propose early intervention strategies and search for additional targetable endothelial injury pathways.

Thrombotic microangiopathy (TMA) after hematopoietic stem cell transplant (HSCT) associated with terminal complement activation, as measured by elevated plasma terminal complement (sC5b-9) concentrations, has a very high mortality. The complement inhibitor eculizumab may be a therapeutic option for HSCT-associated TMA. We examined the pharmacokinetics and pharmacodynamics (PK/PD) of eculizumab in children and young adult HSCT recipients with TMA and activated complement to determine drug dosing requirements for future efficacy trials. We analyzed prospectively collected laboratory samples and clinical data from 18 HSCT recipients with high-risk TMA presenting with complement activation who were treated with eculizumab. We measured eculizumab serum concentrations, total hemolytic complement activity (CH50), and plasma sC5b-9 concentrations. Population PK/PD analyses correlated eculizumab concentrations with complement blockade and clinical response and determined inter-individual differences in PK parameters. We also compared transplant survival in patients treated with eculizumab (n=18) to patients with the same high-risk TMA features who did not receive any targeted therapy during a separate prospective observational study (n=11). In the PK analysis, we found significant inter-patient variability in eculizumab clearance, ranging from 16 to 237 mL/hr/70kg in the induction phase. The degree of complement activation measured by sC5b-9 concentrations at the start of therapy, in addition to actual body weight, were significant determinants of eculizumab clearance and disease response. Sixty one percent of treated patients had complete resolution of TMA and were able to safely discontinue eculizumab without disease recurrence. Overall survival was significantly higher in treated subjects compared to untreated patients (56% versus 9%, p=0.003). Complement blocking therapy is associated with improved survival in HSCT patients with high-risk TMA who historically have dismal outcomes, but eculizumab pharmacokinetics in HSCT recipients differ significantly from reports in other diseases like atypical hemolytic uremic syndrome and paroxysmal nocturnal hemoglobinurina. Our eculizumab dosing algorithm, including pre-treatment plasma sC5b-9 concentrations, patient’s actual body weight, and the first eculizumab dose (mg), accurately determined eculizumab concentration-time profiles for HSCT recipients with high-risk TMA. This algorithm may guide eculizumab treatment and ensure that future efficacy studies use the most clinically appropriate and cost-efficient dosing schedules.

Objectives: In-hospital pediatric sepsis mortality has decreased substantially, but long-term mortality and morbidity among children initially surviving sepsis, is unknown. Accordingly, the Life After Pediatric Sepsis Evaluation investigation was conducted to describe the trajectory of mortality and health-related quality of life morbidity for children encountering community-acquired septic shock. Design: Prospective, cohort-outcome study, conducted 2013–2017. Setting: Twelve academic PICUs in the United States. Patients: Critically ill children, 1 month to 18 years, with community-acquired septic shock requiring vasoactive-inotropic support. Interventions: Demographic, infection, illness severity, organ dysfunction, and resource utilization data were collected daily during PICU admission. Serial parent proxy-report health-related quality of life assessments were obtained at baseline, 7 days, and 1, 3, 6, and 12 months following PICU admission utilizing the Pediatric Quality of Life Inventory or Stein-Jessop Functional Status Scale. Measurements and Main Results: Among 389 children enrolled, mean age was 7.4 ± 5.8 years; 46% were female; 18% were immunocompromised; and 51% demonstrated chronic comorbidities. Baseline Pediatric Overall Performance Category was normal in 38%. Median (Q1–Q3) Pediatric Risk of Mortality and Pediatric Logistic Organ Dysfunction scores at PICU admission were 11.0 (6.0–17.0) and 9.0 (6.0–11.0); durations of vasoactive-inotropic and mechanical ventilation support were 3.0 days (2.0–6.0 d) and 8.0 days (5.0–14.0 d); and durations of PICU and hospital stay were 9.4 days (5.6–15.4 d) and 15.7 days (9.2–26.0 d). At 1, 3, 6, and 12 months following PICU admission for the septic shock event, 8%, 11%, 12%, and 13% of patients had died, while 50%, 37%, 30%, and 35% of surviving patients had not regained their baseline health-related quality of life. Conclusions: This investigation provides the first longitudinal description of long-term mortality and clinically relevant, health-related quality of life morbidity among children encountering community-acquired septic shock. Although in-hospital mortality was 9%, 35% of survivors demonstrated significant, health-related quality of life deterioration from baseline that persisted at least 1 year following hospitalization for septic shock.

Objective Septic shock heterogeneity has important implications for clinical trial implementation and patient management. We previously addressed this heterogeneity by identifying 3 putative subclasses of children with septic shock based exclusively on a 100-gene expression signature. Here we attempted to prospectively validate the existence of these gene expression-based subclasses in a validation cohort. Design Prospective observational study involving microarray-based bioinformatics. Setting Multiple pediatric intensive care units in the United States. Patients Separate derivation (n=98) and validation (n=82) cohorts of children with septic shock. Interventions None other than standard care. Measurements and Main Results Gene expression mosaics of the 100 class-defining genes were generated for 82 individual patients in the validation cohort. Using computer-based image analysis, patients were classified into 1 of 3 subclasses (“A”, “B”, or “C”) based on color and pattern similarity relative to reference mosaics generated from the original derivation cohort. After subclassification, the clinical database was mined for phenotyping. Subclass A patients had higher illness severity relative to subclasses B and C, as measured by maximal organ failure, fewer ICU-free days, and a higher PRISM score. Patients in subclass A were characterized by repression of genes corresponding to adaptive immunity and glucocorticoid receptor signaling. Separate subclass assignments were conducted by 21 individual clinicians, using visual inspection. The consensus classification of the clinicians had modest agreement with the computer algorithm. Conclusions We have validated the existence of subclasses of children with septic shock based on a biologically relevant, 100-gene expression signature. The subclasses have relevant clinical differences.

We report a 63% survival to pediatric intensive care unit discharge, with 45% surviving at a median follow-up of over 2 yrs for all hematopoietic stem cell transplantation patients admitted to our pediatric intensive care unit over a 6-yr period. Our data suggest improved survival outcomes for this high risk patient population.

Objectives: A companion article reports the trajectory of long-term mortality and significant health-related quality of life disability among children encountering septic shock. In this article, the investigators examine critical illness factors associated with these adverse outcomes. Design: Prospective, cohort-outcome study, conducted 2013–2017. Setting: Twelve United States academic PICUs. Patients: Critically ill children, 1 month to 18 years, with community-acquired septic shock requiring vasoactive-inotropic support. Interventions: Illness severity, organ dysfunction, and resource utilization data were collected during PICU admission. Change from baseline health-related quality of life at the month 3 follow-up was assessed by parent proxy-report employing the Pediatric Quality of Life Inventory or the Stein-Jessop Functional Status Scale. Measurements and Main Results: In univariable modeling, critical illness variables associated with death and/or persistent, serious health-related quality of life deterioration were candidates for multivariable modeling using Bayesian information criterion. The most clinically relevant multivariable models were selected among models with near-optimal statistical fit. Three months following septic shock, 346 of 389 subjects (88.9%) were alive and 43 of 389 had died (11.1%); 203 of 389 (52.2%) had completed paired health-related quality of life surveys. Pediatric Risk of Mortality, cumulative Pediatric Logistic Organ Dysfunction scores, PICU and hospital durations of stay, maximum and cumulative vasoactive-inotropic scores, duration of mechanical ventilation, need for renal replacement therapy, extracorporeal life support or cardiopulmonary resuscitation, and appearance of pathologic neurologic signs were associated with adverse outcomes in univariable models. In multivariable regression analysis (odds ratio [95% CI]), summation of daily Pediatric Logistic Organ Dysfunction scores, 1.01/per point (1.01–1.02), p < 0.001; highest vasoactive-inotropic score, 1.02/per point (1.00–1.04), p = 0.003; and any acute pathologic neurologic sign/event, 5.04 (2.15–12.01), p < 0.001 were independently associated with death or persistent, serious deterioration of health-related quality of life at month 3. Conclusions and Relevance: Biologically plausible factors related to sepsis-associated critical illness organ dysfunction and its treatment were associated with poor outcomes at month 3 follow-up among children encountering septic shock.

Pulmonary hypertension (PH) is a potentially fatal complication of hematopoietic stem cell transplantation (HSCT). Given its nonspecific clinical presentation, it is likely that this clinical entity is underdiagnosed after HSCT. Data describing the incidence, risk factors, and etiology of PH in HSCT recipients are minimal. Physicians caring for HSCT recipients should be aware of this severe post-transplant complication because timely diagnosis and treatment may allow improved clinical outcomes. We summarize the pathophysiology, clinical presentation, diagnosis, and management of PH in HSCT recipients.