Phenylalanine ammonia-lyase from yeast was evaluated for its chemotherapeutic effectiveness against the murine L5178Y lymphoblastic leukemia maintained in C57BL/6 × DBA/2 F1 (BD2F1) mice. This enzyme, administered at concentrations of 300 units/kg, rapidly lowered plasma phenylalanine and tyrosine levels, inhibited tumor growth, and produced cures in 40% of the mice. Partially purified preparations of this enzyme, coupled with diets containing low levels of phenylalanine, significantly increased the average life-span of the mice and also produced cures. These results suggest that phenylalanine ammonia-lyase may be a valuable new chemotherapeutic agent for the treatment of some neoplasms.

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This study was supported in part by USPHS Research Grant CA-11732 from the National Cancer Institute.

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©1973 American Association for Cancer Research.
1973
Cancer Research, Inc.