In this study of lyophilized pegaspargase in Japanese patients with newly diagnosed, untreated ALL, all 26 patients achieved a plasma asparaginase activity of ≥ 0.1 IU/ml, the threshold for securing sustained asparagine depletion [16], rapidly (within 5 min), which was maintained until 14 days after the first dose of lyophilized pegaspargase. This evidence concerns the gene ASPG and acute lymphoblastic leukemia.