In vivo, a moderate uptake was observed for[99mTc]Tc-labeled ZHER3-ABD-ZHER3-mcDM1 in HER3 expressing BxPC3 tumors (3.5 ± 0.3%IA/g) at 24h after injection, and clearance was predominately renal-mediated.Treatment of mice with BxPC3 human pancreatic cancer xenografts showedthat a combination of ZHER3-ABD-ZHER3-mcDM1and its cytostatic analog ZHER3-ABD-ZHER3 wasefficacious and superior to treatment with only ZHER3-ABD-ZHER3, providing tumor growth inhibition and longer median survival(90 d) in comparison to monotherapy (68 d) and vehicle control (49d). The gene discussed is ERBB3; the disease is familial pancreatic carcinoma.