Combination chemotherapy of human renal cell carcinoma in athymic nude mice with human lymphoblastoid interferon (HLBI) and UFT, 5-Fu

The effectiveness of interferon alpha (HLBI) for nude mouse transplantable human renal cell carcinoma 72nd general meeting, in combination with UFT and 5-Fu, was examined using, 1 x 10(7) IU/kg, 2 x 10(7) IU/kg HLBI; 25 mg/kg 5-Fu; and 10 mg/kg, 20 mg/kg UFT, administered for 10 consecutive days. The ratio of relative mean tumor weight of treated group to control group was under 42% for the combination of 25 mg/kg (I.P.) 5-Fu, 20 mg/kg UFT, and HLBI and the effect was particularly clear for the combination with 2 x 10(7) IU/kg which indicated a grade IIA histologic classification. In comparison with the control groups only UFT (20 mg/kg) and HLBI (2 x 10(7) IU/kg) showed significant inhibition when administered alone. Although none of the drugs had an inhibitory effect when administered alone, in combined use they showed a strong antitumor effect which was more than synergistic. Orally administered 5-Fu showed a statistically significant difference only in the combination with 2 x 10(7) IU/kg HLBI. Furthermore, the concentration of 5-Fu in the tumor tissue was not affected by the route of administration or drug combination, whereas that in the serum was below the limit of detection in the intraperitoneally administered cases, 0.0096 +/- 0.0079 microgram/ml, lower than the value for orally administered cases. The 5-Fu concentration was 0.026 +/- 0.012 microgram/ml for orally administered UFT which was significantly higher than the value obtained for orally administered 5-Fu. Thus, combination therapy of HLBI and UFT for renal cell carcinoma is expected to be clinically useful.