Kohorst, Mira

A 13-year-old male undergoing maintenance chemotherapy with methotrexate and 6-mercaptopurine (6MP), for very high-risk B-cell acute lymphoblastic leukemia (ALL), presented with vomiting due to severe hypoglycemia with metabolic acidosis. While his laboratory values were concerning for a critically ill child, the patient was relatively well appearing. Hypoglycemia is a rare but serious side effect of 6MP with an unexpectedly variable presentation; therefore, a high index of suspicion is needed for its prompt detection and treatment. This patient also had severe metabolic acidosis, likely secondary to hypoglycemia, creating a serious clinical picture despite a well-appearing child. This example of incongruity between laboratory tests and clinical appearance adds nuance to the existing literature. Moreover, although 6MP-associated hypoglycemia is rare, it may be more prevalent than the literature suggests, as symptoms of hypoglycemia—nausea, vomiting, and somnolence—mirror common chemotherapy side effects. 6MP-induced hypoglycemia can be ameliorated with the addition of allopurinol to shunt metabolism in favor of the production of therapeutic metabolites over hepatotoxic metabolites. Additionally, a morning administration of 6MP and frequent snacks may also help to prevent hypoglycemia. Overall, this case adds to the literature of unusual reactions to 6MP including hypoglycemia in an older child without traditional risk factors.

AbstractRelapsed and refractory B‐cell acute lymphoblastic leukemia (B‐ALL) is an aggressive B‐cell neoplasm associated with poor outcomes. Conventional multiagent chemotherapy and bispecific antibody therapy may induce remission; however, relapse rates remain high and overall survival is poor. Chimeric antigen receptor T‐cell (CAR‐T) therapy provides durable, deep complete remission, and long‐term cures in relapsed and refractory B‐ALL. However, with this new treatment modality, 10%–30% of patients do not achieve remission, and over 50% experience relapse after therapy. Currently, there are two approved CD19‐specific CAR‐T cell constructs in B‐ALL, Tisagenlecleucel and Brexucabtagene Autoleucel by the United States Food and Drug Administration, and the European Medicines Agency (EMA). In this review, we discuss patients, disease, and CAR‐T predictors of outcomes in B‐ALL. We describe the two approved CD19‐directed CAR‐T cell products, review the current literature, and discuss factors associated with high risks of therapy failure and future direction in CAR‐T cell therapy for B‐ALL.