Use of Eculizumab in Pediatric Patients With Transplant Associated Thrombotic Microangiopathy

Background: Transplant-associated thrombotic microangiopathy (TA-TMA) is a serious complication of hematopoietic stem cell transplantation (HSCT) associated with high morbidity and mortality. High-risk TA-TMA (hrTA-TMA) is characterized by multifactorial endothelial damage caused by environmental stressors, dysregulation of the complement system, and genetic predisposition. Complement inhibitors have significantly decreased mortality and are the current treatment of choice. In this article, we describe our experience with the use of eculizumab in pediatric patients diagnosed with hrT-TMA after HSCT. Method: Retrospective study of pediatric patients with hrTA-TMA treated with eculizumab between January 2016 and December 2020. Results: Four pediatric patients aged 1, 12, 14, and 17 years at the time of HSCT were diagnosed with hrTA-TMA and treated with eculizumab during the study. At diagnosis, they all had renal impairment with proteinuria, and hypertension under treatment with at least two antihypertensive drugs. The patient who presented multisystemic involvement died instead of treatment. The three patients with exclusive renal involvement achieved TA-TMA resolution after treatment with eculizumab for 65, 52, and 40.6 weeks and were able to stop treatment. The two patients with follow-up data one year after eculizumab withdrawal sustained a favorable response. Eculizumab was well tolerated, and with adequate vaccination and antibiotic prophylaxis, did not increase the risk of infection. Conclusions: Eculizumab appears to be both safe and effective for the treatment of hrTA-TMA in patients with renal impairment. Early diagnosis and initiation of treatment may improve response. Eculizumab withdrawal can be contemplated in patients who achieve laboratory and clinical resolution of TA-TMA.

Pediatric acute graft-versus-host disease prophylaxis and treatment: surveyed real-life approach reveals dissimilarities compared to published recommendations

Pediatric allogeneic hematopoietic cell transplantation (HCT) practices differ from those of adults, particularly the heterogeneity of transplantable nonmalignant diseases and the lower incidence of graft‐versus‐host disease (GVHD). Several guidelines regarding the management of acute (a) GVHD in adult HCT have been published. We aimed to capture the real‐life approaches for pediatric aGVHD prophylaxis/treatment, and data from 75/193 (response rate 39%) EBMT centers (26 countries) were included, representing half (48%) of the pediatric EBMT‐HCT activity. Results with ≥75% approval from respondents (74/75) for GVHD prophylaxis after myeloablative HCT for malignancies partially contradict published guidelines: Single‐agent cyclosporine A (CsA) was used for matched sibling donor HCT in 47%; blood CsA levels were reported lower; the relapse risk in malignant diseases influenced GVHD prophylaxis with early withdrawal of CsA; distinct longer duration of CsA was employed in nonmalignant diseases. Most centers used additional anti‐thymocyte globulin for matched unrelated and mismatched donor HCT, but not for matched siblings. Regarding prophylaxis in nonmyeloablative conditioning (mainly for nonmalignant diseases), responses showed broad heterogeneity. High conformity was found for first‐line treatment; however, results regarding steroid‐refractory aGVHD indicate an earlier diagnosis in children. Our findings highlight the need for standardized pediatric approaches toward aGVHD prophylaxis/treatment differentiated for malignant and nonmalignant underlying diseases.

Long-term follow-up of IPEX syndrome patients after different therapeutic strategies: An international multicenter retrospective study

Background

Immunodysregulation polyendocrinopathy enteropathy x-linked(IPEX) syndromeis a monogenic autoimmune disease caused by FOXP3 mutations. Because it is a rare disease, the natural history and response to treatments, including allogeneic hematopoietic stem cell transplantation (HSCT) and immunosuppression (IS), have not been thoroughly examined.

Objective

This analysis sought to evaluate disease onset, progression, and long-term outcome of the 2 main treatments in long-term IPEX survivors.

Methods

Clinical histories of 96 patients with a genetically proven IPEX syndrome were collected from 38 institutions worldwide and retrospectively analyzed. To investigate possible factors suitable to predict the outcome, an organ involvement (OI) scoring system was developed.

Results

We confirm neonatal onset with enteropathy, type 1 diabetes, and eczema. In addition, we found less common manifestations in delayed onset patients or during disease evolution. There is no correlation between the site of mutation and the disease course or outcome, and the same genotype can present with variable phenotypes. HSCT patients (n = 58) had a median follow-up of 2.7 years (range, 1 week-15 years). Patients receiving chronic IS (n = 34) had a median follow-up of 4 years (range, 2 months-25 years). The overall survival after HSCT was 73.2% (95% CI, 59.4-83.0) and after IS was 65.1% (95% CI, 62.8-95.8). The pretreatment OI score was the only significant predictor of overall survival after transplant (P = .035) but not under IS.

Conclusions

Patients receiving chronic IS were hampered by disease recurrence or complications, impacting long-term disease-free survival. When performed in patients with a low OI score, HSCT resulted in disease resolution with better quality of life, independent of age, donor source, or conditioning regimen.

Engraftment kinetics and graft failure after single umbilical cord blood transplantation using a myeloablative conditioning regimen

Umbilical cord blood transplant recipients are exposed to an increased risk of graft failure, a complication leading to a higher rate of transplant-related mortality. The decision and timing to offer a second transplant after graft failure is challenging. With the aim of addressing this issue, we analyzed engraftment kinetics and outcomes of 1268 patients (73% children) with acute leukemia (64% acute lymphoblastic leukemia, 36% acute myeloid leukemia) in remission who underwent single-unit umbilical cord blood transplantation after a myeloablative conditioning regimen. The median follow-up was 31 months. The overall survival rate at 3 years was 47%; the 100-day cumulative incidence of transplant-related mortality was 16%. Longer time to engraftment was associated with increased transplant-related mortality and shorter overall survival. The cumulative incidence of neutrophil engraftment at day 60 was 86%, while the median time to achieve engraftment was 24 days. Probability density analysis showed that the likelihood of engraftment after umbilical cord blood transplantation increased after day 10, peaked on day 21 and slowly decreased to 21% by day 31. Beyond day 31, the probability of engraftment dropped rapidly, and the residual probability of engrafting after day 42 was 5%. Graft failure was reported in 166 patients, and 66 of them received a second graft (allogeneic, n=45). Rescue actions, such as the search for another graft, should be considered starting after day 21. A diagnosis of graft failure can be established in patients who have not achieved neutrophil recovery by day 42. Moreover, subsequent transplants should not be postponed after day 42.