[Methionine-deprived amino acid solution-induced biochemical modulation of 5-FU and augmentation of the antitumor activity].

A randomized study of the effects of methionine-deprived amino acid solution (AO-90) on the metabolism of 5-FU was performed in patients with advanced gastric or colorectal cancers. Continuous intravenous hyperalimentation with either AO-90 or conventional amino acid solution (control group) in combination with 5-FU was performed for 7 days preoperatively under the fasting condition. The administration of AO-90 showed a decreased level of serum methionine and resulted in the subsequent increased tendency in the intratumorous levels of both folic acid and methylene tetrahydrofolate compared to those of the control group. In the AO-90 group, the inhibition rate of thymidilate synthase in the tumor was significantly higher than that of the control group. These results indicate that AO-90 plays an important role in the metabolism of 5-FU and seems to contribute to the increased antitumor effect of 5-FU as a biochemical modulator.