Abstract
Methotrexate is a chemotherapeutic and anti-inflammatory agent used in
cancers, hematologic and rheumatologic diseases, binding to
Dihydrofolate Reductase (DHFR) as a competitive inhibitor, modulating
inflammation by inhibition of transmethylation reactions.1,2 Life
threatening hypersensitivity reactions (HSRs) have been reported with
methotrexate. 3,4,5 Alternative treatments result in suboptimal
outcomes/ death due to cancer progression. Drug desensitization enables
patients to continue treatment, preventing anaphylaxis by inducing a
temporary tolerance.3 We report a case of a child with Acute B-cell
Lymphoblastic Leukemia who successfully tolerated methotrexate
desensitization, and subsequently weaned to a weekly oral challenge. He
is now taking weekly methotrexate without any reactions.