(A) Antitumor activity of RFB4(dsFv)PE38. Athymic nude mice irradiated on day −3 were inoculated with 107 CA46 cells on day 0. Beginning on day 1, injections of 5, 2, or 1 μg RFB4(dsFv)PE38 or PBS/0.2% BSA were given every day for four doses. Tumor growth was monitored by measuring tumor volume and is expressed as the average tumor volume of each group. Control mice were killed before the end of the 21-day observation period because their tumor volumes would have exceeded humane limits. (□), 5 μg; (▴), 2 μg; (○), 1 μg; (▪), PBS/0.2% BSA diluent control. Data are from one of two experiments that gave similar results. (B) Antitumor activity of RFB4(dsFv)PE38. Athymic nude mice irradiated on day −4 were inoculated with 5 × 106 CA46 cells on day 0. Beginning on day 1, injections of 5, 3, or 1 μg RFB4(dsFv)PE38, 5 μg nonrelevant control dsFv-PE38 immunotoxin, or PBS/0.2% BSA diluent were given every day for four doses. Tumor growth was monitored by measuring tumor volume and is expressed as the average tumor volume of each group. (□), 5 μg; (▴), 3 μg; (○), 1 μg; (+), 5 μg nonrelevant control dsFv-PE38 immunotoxin; (▪), PBS/0.2% BSA diluent control. Data are from one of two experiments that gave similar results.
