Acute lymphocytic leukemia maintenance therapy

A 45-year-old male on combination therapy for remission-maintenance acute lymphocytic leukemia develops suprapubic pain, dysuria, and hematuria. Evidence of hemorrhage and inflammation is apparent on cystoscopy of the urinary bladder. Which of the following agents most likely caused these findings ... 

Bestatin (ubenimex) is a potent inhibitor of aminopeptidase N and aminopeptidase B,89 which was isolated from a culture filtrate of Streptomyces olivoreticuli during the search for specific inhibitors of enzymes present on the membrane of eukaryotic cells.90 Inhibitors of aminopeptidase activity are associated with macrophage activation and differentiation, Bestatin has shown significant therapeutic effects in several clinical trials.91 In a multi-institutional study,92 patients with acute non-lymphocytic leukemia (ANLL) were randomized to receive either Bestatin or placebo orally after completion of induction and consolidation therapy, and concomitant with maintenance chemotherapy. Remission duration was prolonged in the Bestatin group, although this difference did... 

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