[In vivo chemosensitivity test for UFT and FT-207. I--Subrenal capsule assay]

A chemosensitivity test for UFT and FT-207, which are used in long-term administration clinically, was investigated for prediction of clinical response. Five transplantation-established human tumor xenograft systems were examined using subrenal capsule assay. Both anticancer agents showed antiproliferative effects according to the total administered dose. Two of 5 tumors were determined to be sensitive to UFT using microscopic measurements following intragastric administration of 1/2 of the LD50 value, while they were shown to be resistant to 5-FU. In these two cases, prolongation of life span by long-term administration of UFT was shown clinically. All these experiments could be performed on condition that the loss of body weight in mice was less than 20%. These results suggest that in the 4-day subrenal capsule assay, clinical responses to long-term administration of UFT or FT-207 are predictable using intragastric high-dose administration which does not induce more than 20% body weight loss in experimental mice.