Proceedings of the Workshop on Amino Acid Imbalance in the Treatment of Cancer. Introduction: possibilities for biochemically rational chemotherapy for some malignancies with depleting enzymes and antimetabolites of specific amino acids.

A number of recent investigations have documented that, in several cancers, the malignant cells are no longer capable of synthesizing a specific amino acid, while the normal cells continue such biosynthesis at a normal rate. Enzymes degrading amino acids have demonstrated therapeutic value against such cancers. Significant progress was made recently in technology related to enzyme preparations. These are highly specific, have long half-lives, and can be chemically modified to eliminate their immunogenicity to man or animals. A practical in vitro system for detection of antimetabolites of different amino acids in natural materials was developed. It appears reasonable to expect that, in a specific malignancy, after the available pools of such deficient amino acids are exhausted by administration of the depleting enzyme, an additional, perhaps synergistic, effect could be obtained by utilizing an analog of such an amino acid. A brief review of the pertinent existing information will be presented in this communication.