This is a prospective international multi-center registry and biorepository trial of children and adolescents/young adults (AYA) undergoing hematopoietic cell transplantation (HCT) to assess the impact of endotheliopathies in the HCT setting as a contributor of significant morbidity and mortality.

Primary:

• To evaluate the proportion of pediatric patients undergoing hematopoietic cell transplant (HCT) who develop endotheliopathies (SOS, TMA, DAH and IPS) and/or MODS within 100 days of such therapies.
• To evaluate the proportion of pediatric patients undergoing hematopoietic cell transplant (HCT) who experience abnormal levels of circulating angiogenic, vascular permeability and inflammatory factors within 100 days post HCT-CT in the setting of endotheliopathies.

Secondary/Exploratory Objective(s):

• To determine the impact of endotheliopathies in the HCT setting on the overall survival.
• To assess the efficacy of specific prophylaxis and treatment strategies directed at endotheliopathies (SOS, TMA, DAH and IPS) post-HCT among enrolled children on overall survival.
• To assess whether exposure to immunotherapies (CAR-T, PD-1 Inhibitors, bispecific T-cell engager (BiTE) antibodies and antibody drug conjugates) prior to HCT affects post-HCT outcomes (endotheliopathies and MODS).

Inclusion Criteria:

• Children, adolescents and young adults (AYA) 0-26 years of age undergoing HSCT.
• Recipients of autologous and allogeneic HSCT.
• Any preparative regimen.

Exclusion Criteria:

• Any patient who does not consent/assent to participation.
• Any patient for whom 5 mL blood sample(s) drawn at specified intervals would pose any more than minimal risk, as defined by institutional guidelines and at discretion of treating physician will be ineligible for biorepository banking.

Children, adolescents and young adults (AYA) 0-26 years of age undergoing HSCT.