(484) Therapy-Resistant Transplant-Associated Thrombotic Microangiopathy in a Pediatric Patient

Introduction: Transplant-associated thrombotic microangiopathy (TA-TMA) is a serious, life-threatening complication of hematopoietic stem cell transplantation (HSCT), characterized by microangiopathic hemolytic anemia, hypertension with renal failure, and central nervous system dysfunction. Severe TA-TMA has a mortality rate over 50%, highlighting the importance of comprehensive studies and case reports to improve treatment strategies and patient outcomes.

Description: This case describes a 6-year-old Hispanic female with high-risk neuroblastoma treated with autologous tandem HSCT. The patient developed TA-TMA, resulting in compromised renal function, complicated with anemia, hemolysis, proteinuria, tubular acidosis, thrombocytopenia, electrolyte imbalance, gastritis, hypovitaminosis D, and severe pericardial effusions, requiring pediatric intensive care unit (PICU) admission. Multiple interventions were performed including pericardiocentesis, pericardial window and hemodialysis. Once diagnosed, she began monoclonal antibody therapy and antimicrobial prophylaxis due to immunosuppression. Markers used to follow her TMA response to treatment were: Haptoglobin levels, platelets, LDH, C3 and C4 levels, CH50, AH50.

Despite a prolonged course of monoclonal antibody treatment with Eculizumab and Ravulizumab, her condition continued to deteriorate. She also received complementary treatment with methylprednisolone, acetylcysteine, Rituximab and Basiliximab. Although her TMA has been persistently treated, her TMA markers worsen, for this reason compassionate use of Narsoplimab was recommended.

Discussion: Managing TA-TMA and its complications is challenging and requires close monitoring of the patient’s status, including frequent assessments of renal function, blood counts, coagulation profiles, and specific markers to detect worsening microangiopathy. This case emphasizes the need for a multidisciplinary approach including Hematologist, Oncologist, Nephrologist, Transplant team and Critical Care. In addition, it stresses the importance of further research into TA-TMA and its treatment options.