Asparaginase is well recognized as a crucial element in the treatment of
pediatric acute lymphoblastic leukemias (ALL).1 It is
an enzyme that exerts its anti-leukemic effects by catalyzing the
breakdown of asparagine to aspartic acid and ammonia.1The E. coli -derived asparaginase formulations, L-asparaginase and
pegaspargase, have high rates of antibody development that can
ultimately lead to inadequate asparaginase activity.2To combat this, Erwinia chrysanthemi -derived asparaginase was
developed, of which several products exist: conventional Erwinia
asparaginase (Erwinaze), and, the newest formulation, recombinant
Erwinia asparaginase (Rylaze).2,3
As ammonia is a byproduct of asparaginase’s mechanism, acute, transient
hyperammonemia is expected.4,5 Symptomatic
hyperammonemia may present as headache, nausea, vomiting, lethargy, or
in severe cases, encephalopathy, coma, or death.6–8There are several case reports describing symptomatic hyperammonemia in
patients receiving pegaspargase and conventional Erwinia asparaginase,
but herein we describe two patients who developed symptomatic
hyperammonemia secondary to recombinant Erwinia
asparaginase.6,9,10