A retrospective study was undertaken comparing the frequency and severity of anaphylactic reactions to E. coli-derived and Erwinia-derived asparaginase given intravenously on a weekly dosage schedule. Both drugs were found to produce life-threatening hypersensivity reactions with the chance of reaction per dose administered being almost identical--8% for each dose administered. Eleven of 31 patients (35%) experienced anaphylactic reactions, 9/27 (33%) with E. coli and 3/10 (30%) with Erwinia asparaginase, with one patient suffering anaphylaxis to both preparations. A marked increase in the percentage of patients having reactions occurred after the fourth dose of either preparation, with the incidence per dose increasing from 3.3% with the first dose to 32% on the fifth and subsequent doses. Rationale for an antibody-mediated allergic reaction is presented to explain the data.

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The "late" relapse patterns of childhood acute leukemia were studied in 83 children in their first continuous complete remission for more than three years prior to randomization for stopping therapy (40 patients) or continuing therapy (43 patients) for a total of six years. Twenty of 83 (22.9%) have relapsed: Ten in the bone marrow, one in the central nervous system, and nine in the testes. The testes relapse rate of 41.1% (7/17) in males discontinuing therapy at three years was much higher than that of 8.7% (2/23) in males continuing therapy. This difference is significant at P = 0.01 (Wilcoxon test).