Radioimmuntherapy assay. (A) Tumor size variations in individual nude mice engrafted with the MDA-MB-468 cell line after treatment. Mice treated with 14.8 (n = 8) or 22.2 MBq (n = 8) of 131I-labeled B-B4 mAb can be compared with control mice (n = 9) that received unlabeled B-B4 mAb. The mean tumor volume of each group of mice is represented. The curves are very significantly different for the control versus 22.2 MBq (p < 0.0001) and the 14.8 MBq versus the 22.2 MBq groups (p < 0.0001) and significantly different for the control versus the 14.8 MBq groups (p = 0.028). (B) The effect of the unlabeled B-B4 mAb (n=5) and PBS (n=5) were tested in an independent experiment (left panel). The effect of RIT with 131I-labeled control isotype mAb (14.8, n=3 and 25.9 MBq, n=4) and 131I-B-B4 (14.8, n=4 and 22.2 MBq, n=4) and control PBS (n=4) were compared (right panel). Results are expressed as fold-increase in tumor volume compared to day 0. This figure summarizes the results of two independent assays performed under the same conditions. (C) The time required for tumors to double in size in groups given 14.8 and 22.2 MBq 131I-labeled B-B4 mAb compared with the control group..