Novel [In-111]In-BnDTPA-EphA2-230-1 Antibody for Single-Photon Emission Computed Tomography Imaging Tracer Targeting of EphA2

Erythropoietin-producing hepatocellular receptor A2 (EphA2) is overexpressed in cancer cells and causes abnormal cell proliferation. Therefore, it has attracted attention as a target for diagnostic agents. In this study, the EphA2-230-1 monoclonal antibody (EphA2-230-1) was labeled with [In-111]In and evaluated as an imaging tracer for single-photon emission computed tomography (SPECT) of EphA2. EphA2-230-1 was conjugated with 2-(4-isothiocyanatoben-zyl)-diethylenetriaminepentaacetic acid (p-SCN-BnDTPA) and then labeled with [In-111]In. [In-111]In-BnDTPA-EphA2-230-1 was evaluated in cell-binding, bio-distribution, and SPECT/computed tomography (CT) studies. The cellular uptake ratio of [In-111]In-BnDTPA-EphA2-230-1 was 14.0 +/- 2.1%/mg protein at 4 h in the cell-binding study. In the biodistribution study, a high uptake of [In-111]In-BnDTPA-EphA2-230-1 was observed in tumor tissue (14.6 +/- 3.2% injected dose/g at 72 h). The superior accumulation of [In-111]In-BnDTPA-EphA2-230-1 in tumors was also confirmed using SPECT/CT. Therefore, [In-111]In-BnDTPA-EphA2-230-1 has potential as a SPECT imaging tracer for EphA2.