Universal premedication and therapeutic drug monitoring for asparaginase-based therapy prevents infusion-associated acute adverse events and drug substitutions.

Abstract

Asparaginase is a critical component of lymphoblastic leukemia therapy, with intravenous pegaspargase (PEG) as the current standard product. Acute adverse events (aAEs) during PEG infusion are difficult to interpret, representing a mix of drug-inactivating hypersensitivity and noninactivating reactions. Asparaginase Erwinia chrysanthemi (ERW) is approved for PEG hypersensitivity, but is less convenient, more expensive, and yields lower serum asparaginase activity (SAA). We began a policy of universal premedication and SAA testing for PEG, hypothesizing this would reduce aAEs and unnecessary drug substitutions. Retrospective chart review of patients receiving asparaginase before and after universal premedication before PEG was conducted, with SAA performed 1week later. We excluded patients who had nonallergic asparaginase AEs. Primary end point was substitution to ERW. Secondary end points included aAEs, SAA testing, and cost. We substituted to ERW in 21 of 122 (17.2%) patients pre-policy, and 5 of 68 (7.4%) post-policy (RR, 0.427; 95% CI, 0.27-0.69, P=0.028). All completed doses of PEG yielded excellent SAA (mean, 0.90 units/mL), compared with ERW (mean, 0.15 units/mL). PEG inactivation post-policy was seen in 2 of 68 (2.9%), one silent and one with breakthrough aAE. The rate of aAEs pre/post-policy was 17.2% versus 5.9% (RR, 0.342; 95% CI, 0.20-0.58, P=0.017). Grade 4 aAE rate pre/post-policy was 15% versus 0%. Cost analysis predicts $125779 drug savings alone per substitution prevented ($12402/premedicated patient). Universal premedication reduced substitutions to ERW and aAE rate. SAA testing demonstrated low rates of silent inactivation, and higher SAA for PEG. A substantial savings was achieved. We propose universal premedication for PEG be standard of care.