Figure 4

Dose response distribution of trastuzumab in relation to blood vessels and regions of hypoxia in 231-H2N xenografts. Left panels show the distribution of trastuzumab (blue) in relation to blood vessels (red) and regions of hypoxia (green) in MDA-MB-231 breast cancer xenografts transfected with ErbB2 (231-H2N) at 2 h after i.v. injection of (A) 0.1 mg, (B) 0.3 mg and (C) 1.0 mg. In right panels staining intensity (mean +/- SEM) due to trastuzumab is plotted against distance from the nearest blood vessel in the tumor section. Note minimal drug binding in hypoxic regions. Scale bar = 100 μm.