A 12-Step Desensitization Protocol for Calaspargase Pegol-mknl

Asparaginase is a standard treatment for acute lymphoblastic leukemia (ALL) of childhood. As a bacteria-derived enzyme, asparaginase is highly immunogenic, and hypersensitivity reactions (HSRs) routinely lead to drug discontinuation. HSRs remain common even with the introduction of pegaspargase, a PEGylated version of <i>Escherichia coli</i>-derived asparaginase. Asparaginase <i>Erwinia chrysanthemi</i> (recombinant)-rywn (recombinant Erwinia) is an alternative for those with HSRs to pegaspargase. Here, we describe an 11-year-old boy with relapsed ALL who developed HSRs to both pegaspargase and recombinant Erwinia. This is the report of a novel desensitization protocol for calaspargase pegol-mknl (calaspargase) with no adverse events and adequate serum asparaginase activity.