Iigo M, Hoshi A, Kitagawa H
J Cancer Res Clin Oncol. 1986;111(3):187-90. doi: 10.1007/BF00389232.
The chemotherapeutic action of tegafur (FT) against adenocarcinoma 755 in mice was markedly potentiated by oral administration of L-cysteine and L-cystine without increasing its toxicity. In particular, the combination of FT at 200 mg/kg per day (maximum dose) and 1000 mg/kg per day of L-cystine markedly inhibited tumor growth. The dose ratio of L-cysteine or L-cystine to FT needs 5 by weight to potentiate the antitumor activity of FT. The antitumor activity of 5-fluorouracil (FU) was slightly, but not significantly, increased by L-cysteine. The total concentration of FT in the plasma and the tumor when it was given in combination with L-cystine was significantly increased when compared with FT alone 1 h after oral administration. The FU level in the plasma after administration of the combination of FT and L-cystine was three times higher than that after FT alone, and the FU level in the tumor after treatment with the combination of FT and L-cystine was also higher (about 20%) than that after FT alone. This significant increase in FT and FU levels in the plasma and the tumor may be related to the potentiation of the antitumor activity of FT by L-cystine.
口服L-半胱氨酸和L-胱氨酸可显著增强替加氟（FT）对小鼠腺癌755的化疗作用，且不增加其毒性。特别是，每天200mg/kg（最大剂量）的FT与每天1000mg/kg的L-胱氨酸联合使用可显著抑制肿瘤生长。L-半胱氨酸或L-胱氨酸与FT的重量比需要达到5才能增强FT的抗肿瘤活性。L-半胱氨酸可使5-氟尿嘧啶（FU）的抗肿瘤活性略有增加，但不显著。与单独口服FT相比，口服FT与L-胱氨酸联合给药1小时后，血浆和肿瘤中FT的总浓度显著增加。FT与L-胱氨酸联合给药后血浆中的FU水平比单独使用FT时高3倍，FT与L-胱氨酸联合治疗后肿瘤中的FU水平也高于单独使用FT时（约20%）。血浆和肿瘤中FT和FU水平的显著增加可能与L-胱氨酸增强FT的抗肿瘤活性有关。
