Figure 1.

In vitro analysis of cell binding by astatine‐211‐labeled trastuzumab (²¹¹At‐tras) and subsequent cell death. (a) Human epidermal growth factor receptor 2 (HER2) expression in MKN45, N87, SKBR3, MKN7, and AU565 cells. α‐Tubulin was used as a loading control. Ratios of the band intensity of HER2 relative to α‐tubulin are indicated below the images. (b) Cell binding ratio of ²¹¹At‐trastuzumab to N87 and MKN45 cells with/without trastuzumab (mAb) block. Bars are labeled in the graph. Three independent experiments were carried out, each in triplicate (n = 3). (c) Representative images of stained surviving cells at 7 days after 24 h of treatment with PBS control, unlabeled trastuzumab (Tras), ²¹¹At (0.37 or 1.85 kBq), or ²¹¹At‐tras (0.37 or 1.85 kBq). (d) Quantification of the viability of the cells in panel (c) treated with ²¹¹At‐tras for 7 days. Bars are labeled in the graph. Three independent experiments were carried out in triplicate (n = 3). All data represent mean ± SD. *P < 0.05 versus control; **P < 0.05 versus Tras.