Survival of pediatric patients requiring admission in the intensive care unit post hematopoietic stem cell transplantation: Prognostic factors associated with mortality

BACKGROUND

Although hematopoietic stem cell transplantation (HSCT) is the only curative option for some children with malignant and nonmalignant disorders, the procedure itself carries a high risk of complications. A proportion of children undergoing HSCT develop severe transplant-related complications requiring hospitalization in the pediatric intensive care unit (PICU).

METHODS

A retrospective cohort study included 793 children with malignant and nonmalignant diseases that underwent 963 HSCTs in two large pediatric hospitals over 15 years. Ninety-one patients needed 105 (11%) PICU admissions. The objective of the study was to analyze the risk factors associated with morbidity and mortality in children post HSCT who were admitted to the PICU.

RESULTS

Survival rate of a single PICU hospitalization was 43%. Long-term survival rate (classified as 1 year and 3 years) was 29.1% and 14.9% among PICU hospitalized patients compared with 74.6% and 53.3% among patients who had undergone HSCT and did not require PICU hospitalization. Factors found to have a significant negative association with PICU survival were respiratory failure as indication for PICU admission, neutropenia, graft-versus-host disease, mechanical ventilation, inotropic support, need for dialysis, and multiple-organ failure (MOF) with more than one systemic intensive intervention. The strongest prognostic factors associated with mortality were MOF (p < .001) and the need for inotropic support (p = .004).

CONCLUSIONS

Neutropenia was found to be negatively associated with survival, suggesting non-engraftment and late engraftment are important risk factors for HSCT patients hospitalized in PICU. MOF and inotropic support were found to be the main negatively associated predictive factors with survival.

Posttransplant Intramuscular Injection of PLX-R18 Mesenchymal-Like Adherent Stromal Cells Improves Human Hematopoietic Engraftment in A Murine Transplant Model

Late-term complications of hematopoietic cell transplantation (HCT) are numerous and include incomplete engraftment. One possible mechanism of incomplete engraftment after HCT is cytokine-mediated suppression or dysfunction of the bone marrow microenvironment. Mesenchymal stromal cells (MSCs) elaborate cytokines that nurture or stimulate the marrow microenvironment by several mechanisms. We hypothesize that the administration of exogenous MSCs may modulate the bone marrow milieu and improve peripheral blood count recovery in the setting of incomplete engraftment. In the current study, we demonstrated that posttransplant intramuscular administration of human placental derived mesenchymal-like adherent stromal cells [PLacental eXpanded (PLX)-R18] harvested from a three-dimensional in vitro culture system improved posttransplant engraftment of human immune compartment in an immune-deficient murine transplantation model. As measured by the percentage of CD45⁺ cell recovery, we observed improvement in the peripheral blood counts at weeks 6 (8.4 vs. 24.1%, p < 0.001) and 8 (7.3 vs. 13.1%, p < 0.05) and in the bone marrow at week 8 (28 vs. 40.0%, p < 0.01) in the PLX-R18 cohort. As measured by percentage of CD19⁺ cell recovery, there was improvement at weeks 6 (12.6 vs. 3.8%) and 8 (10.1 vs. 4.1%). These results suggest that PLX-R18 may have a therapeutic role in improving incomplete engraftment after HCT.

Virus-Specific T Cells for the Immunocompromised Patient

While progress has been made in the treatment of both hematologic cancers and solid tumors, chemorefractory or relapsed disease often portends a dismal prognosis, and salvage chemotherapy or radiation expose patients to intolerable toxicities and may not be effective. Hematopoietic stem cell transplant offers the promise of cure for many patients, and while mismatched, unrelated or haploidentical donors are increasingly available, the recipients are at higher risk of severe immunosuppression and immune dysregulation due to graft versus host disease. Viral infections remain a primary cause of severe morbidity and mortality in this patient population. Again, many therapeutic options for viral disease are toxic, may be ineffective or generate resistance, or fail to convey long-term protection. Adoptive cell therapy with virus-specific T cells (VSTs) is a targeted therapy that is efficacious and has minimal toxicity in immunocompromised patients with CMV and EBV infections in particular. Products have since been generated specific for multiple viral antigens (multi-VST), which are not only effective but also confer protection in 70–90% of recipients when used as prophylaxis. Notably, these products can be generated from either virus-naive or virus-experienced autologous or allogeneic sources, including partially matched HLA-matched third-party donors. Obstacles to effective VST treatment are donor availability and product generation time. Banking of third-party VST is an attractive way to overcome these constraints and provide products on an as-needed basis. Other developments include epitope discovery to broaden the number of viral antigens targets in a single product, the optimization of VST generation from naive donor sources, and the modification of VSTs to enhance persistence and efficacy in vivo.