A Summary of the Clinical Status of Asparaginase

Abstract

Asparaginase is an agent for the treatment of leukemia which differs from other agents in that it takes advantage of a unique requirement of certain leukemic cells for asparagine, which most normal cells apparently do not have. It has been reported here to produce rapid remissions in acute lymphoblastic leukemia in from 40 to 100% of patients in small series and the average is probably in the order of 60%. There does not appear to be any real cross-resistance with any of the other active agents, but it may be that somewhat higher remission rates are achieved in the previously untreated cases. This seems not to be a question of cross-resistance but rather a reflection of the patient’s better physical condition when seen soon after diagnosis has been made. In small series — and I stress small series because I am afraid of small numbers — approximately the same percentages of remissions are achieved with daily doses from 10 IU/kg to 5000 IU/kg. There may be some evidence, however, that longer unmaintained remissions are achieved by doses of 1000 IU/kg or higher. In acute lymphoblastic leukemia (ALL), children seem to respond perhaps somewhat better than adults. Asparaginase is also active against the meningeal manifestation of the disease, whether the drug is given intravenously or intrathecally.