TABLE 3

Specificity of Binding of ^99mTc-Labeled Affibody Molecules to HER2-Expressing Cells In Vitro

	Cell-associated radioactivity (% of added)
	DU-145		SKOV-3
Affibody molecule	No presaturation	After presaturation	No presaturation	After presaturation
^99mTc-Z_HER2_:V1	11.4 ± 0.2	1.2 ± 0.3	40.4 ± 0.4	1.0 ± 0.2
^99mTc-Z_HER2_:V2	9.3 ± 0.6	1.48 ± 0.05	42.9 ± 1.4	1.8 ± 0.1
^99mTc-Z_HER2_:V3	10.2 ± 0.9	1.4 ± 0.2	51.2 ± 1.7	1.5 ± 0.1
^99mTc-Z_HER2_:V4	8.8 ± 0.4	2.0 ± 0.3	53.1 ± 4.5	3.9 ± 0.2
^99mTc-Z_HER2_:V5	9.0 ± 0.45	1.6 ± 0.2	53.9 ± 1.3	4.7 ± 0.6

Specificity test was performed using DU-145 prostate cancer and SKOV-3 ovarian cancer cell lines. For presaturation of HER2, a 500-fold molar excess of nonradioactive Affibody molecule was added. Data are presented as mean values from 3 cell dishes with SD. Presaturation of HER2 caused significant decrease of binding, which demonstrated specific binding to HER2.