Synthesis and evaluation of Lys1(α,γ-Folate)Lys3(177Lu-DOTA)-Bombesin(1-14) as a potential theranostic radiopharmaceutical for breast cancer

• 177Lu-Folate-BN improves recognition of breast cancer cells positive to FR and GRPR.
• 177Lu-Folate-BN shows theranostic (imaging and radiation therapy) properties.
• The heterobivalent 177Lu-Folate-BN tracer interacts with different targets on tumors.

The aim of this work was to synthesize Lys1(α,γ-Folate)-Lys3(177Lu-DOTA)-Bombesin (1-14) (177Lu-Folate-BN), as well as to assess its potential for molecular imaging and targeted radiotherapy of breast tumors expressing folate receptors (FR) and gastrin-releasing peptide receptors (GRPR). Radiation absorbed doses of 177Lu-Folate-BN (74 MBq, i.v.) estimated in athymic mice with T47D-induced breast tumors (positive to FR and GRPR), showed tumor doses of 23.9±2.1 Gy. T47D-tumors were clearly visible (Micro-SPECT/CT images). 177Lu-Folate-BN demonstrated properties suitable as a theranostic radiopharmaceutical.