ERBB2 and neoplasm: To determine the in vivo tumor-targeting specificity of HCT-mono-mIL12, we first evaluated the biodistribution of DyLight 680-labeled HCT-mono-mIL12 in BALB/c mice bearing dual-flank syngeneic tumors (HER2-expressing CT26-HER2/neu tumors in the right flank and HER2-negative CT26 tumors in the left flank) at an average tumor volume of approximately 300 mm3 (Figure 2A).