Clinical Experience with L-Asparaginase
The administration of L-asparaginase has resulted in reports of beneficial effects in patients with acute leukemia [1–5]. The initial clinical and laboratory studies indicated that L-asparaginase selectively inhibits cancer cells dependent on the nonessential amino acid L-asparagine and offered the promise that L-asparaginase would not be harmful to normal cells. However, later clinical reports dispelled hope for a broad spectrum antitumor effect and also revealed unexpected forms of toxicity [1–7]. Evaluation of the several clinical studies indicates that while the antitumor responses are unique and reproduceable in acute lymphocytic leukemia of children, toxicities are often not consistent in one report compared to another. These differences might be attributable to problems in preparing large quantities of a bacterial protein, and the inclusion of contaminants like endotoxin. In addition it is now possible to obtain L-asparaginase from other species  as well as in crystalline form  although no major studies have been reported with these preparations. Thus one can only evaluate the relative merits and toxicities of specific preparations, because no comparative clinical trials of the various materials are available.
KeywordsAcute Lymphocytic Leukemia Chronic Lymphocytic Leukemia Acute Leukemia Blast Crisis Bone Marrow Toxicity
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