[Antitumor activity of BOF-A2, a new 5-fluorouracil derivative, against human cancers xenografted in nude mice by intermittent administration].

Antitumor effects of BOF-A2 given intermittently was evaluated with human gastric (H-111, H-83), colorectal (H-110, H-143) and lung (H-74, LC-376) cancers xenografted in nude mice and compared with those by continuous administration. BOF-A2 was orally given 3 or 4 times per week at 30 or 35 mg/kg over 4 weeks. This drug was effective to 5 strains except H-110 (IR > or = 58%), remarkably effective to H-81 and H-143 (IR > or = 80%) and caused tumor regression in mice bearing H-81 especially. Moreover, the drug was effective to H-74 which is rather insensitive to 5-FU and its known derivatives. When the drug was given orally to nude mice xenografted LC-376, 5-FU levels in the tumor tissue was notably durative for a long time as compared to UFT. It would be concluded that BOF-A2 was much effective to insensitive tumor to fluorinated pyrimidines or other anticancer, because of persistence of high levels of 5-FU in the tumor tissue. On the other hand, diarrhea which is caused by other fluorinated pyrimidines or consecutive administration of BOF-A2, was mild by the intermittent administration of BOF-A2.