Analysis of the Association Between Hypersensitivity Reactions and Asparaginase Activity Monitoring After Pegaspargase Treatment: A Report of Two Cases

A retrospective analysis was conducted on the clinical data and dynamic monitoring of asparaginase activity in two pediatric patients with high-risk acute lymphoblastic leukemia (ALL) who developed hypersensitivity reactions following pegaspargase (PEG-asp) treatment. Case 1: A 4-year-old male developed lip swelling, abdominal pain, and dyspnea after the fourth dose of PEG-asp, but asparaginase activity remained >100 U/L, suggesting a non-antibody-mediated mechanism. Case 2: A 1-year-old male presented with rash, vomiting, and mucosal edema after the fourth dose, accompanied by a rapid decline in asparaginase activity (<100 U/L from day 7 onward), confirming antibody-mediated hypersensitivity. This report highlights the utility of asparaginase activity monitoring in distinguishing hypersensitivity mechanisms and guiding therapeutic decisions, such as switching enzyme formulations.