Medical application of radiohalogenated peptides; Synthesis and evaluation of F(-I)KCCYSL for targeting HER2

佐々木 一郎; 渡辺 茂樹; 大島 康宏; 須郷 由美; 山田 圭一*; 花岡 宏史*; 石岡 典子

Peptide Science 2015, p.243 - 246, 2016/03

Radioisotope labeled peptides with high affinity to receptors overexpressing on the surface of tumor cells are promising for applications in nuclear medicine such as diagnostic radiography and radiotherapy. Radiohalogens such as I and At are useful for clinical imaging and therapeutic applications, and it can be introduced at the position of phenylalanine residue via electrophilic destannylation. KCCYSL (Lys-Cys-Cys-Tyr-Ser-Leu) is a hexapeptide containing disulfide bond. Previous study revealed that KCCYSL has potential as tumor imaging and therapeutic agent targeting tumor cells overexpressing the human epidermal growth factor receptor type 2 (HER2). In this study, we report synthesis and evaluation of radiohalogenated KCCYSL derivatives. Precursor peptides, Boc-F(-SnBu)K(Boc)C(Trt)C(Trt)Y(Bu)S(Bu)L-OH and Boc-F(-SnBu)GS(Bu)GK(Boc)C(Trt)C(Trt)Y(Bu)S(Bu)L-OH, were synthesized by the Fmoc solid phase peptide synthesis. Then, precursor peptides were radioiodinated via electrophilic destannylation, and they were deprotected to obtain F(-I)KCCYSL and F(-I)GSGKCCYSL in radiochemical yield 15% and 17%, respectively. assays of the radioiodinated peptides for HER2 and stability in serum are being undertaken.