Biodistribution of 125
I-labeled B-B4 mAb. (A) The biodistribution of 125I-labeled B-B4 mAb was estimated in nude mice engrafted with the MDA-MB-468 breast cancer cell line. The results are expressed as mean values ±95% confident intervals of the percentage of injected dose per gram (%ID/g) in the considered organ or tissue from three triplicate assays. (B) This panel shows the specific binding of the B-B4 antibody calculated by subtracting the %ID/g of the 125I-labeled 7D4 isotype-matched control antibody to that of 125I-labeled B-B4 measured in a triplicate assay under the same experimental conditions for both antibodies. (C) The %ID/g of 125I-labeled B-B4 mAb obtained from biodistribution studies at different time points are plotted versus time in order to visualize the kinetics of activity uptake in different tissues. (D) The kinetics of 7D4 and B-B4 distribution in the blood and tumors are shown in the same graph to demonstrate the identical blood pharmacokinetics of both antibodies and the specific uptake of BB4 in the tumor. The difference between the uptake of the two antibodies in the tumor is not significant at 4 h but is clearly significant at 24, 48, and 72 h (p < 0.001 determined by a two-way ANOVA test).