Siam Physics Congress 2015

Development of $^{68}$Ga-peptide for Positron Emission Tomography Tracer

21 May 2015, 08:00

3h

Board: BIO-04

Poster presentation Biological Physics and Biomedical Engineering Poster-2

Speaker

Ms Piriya Kaeopookum (Research and Development Division, Thailand Institute of Nuclear Technology (Public Organization), Nakhonnayok, THAILAND 26120)

Description

Bombesin peptide is crucial for the development of positron emission tomography (PET) tracer for human prostate cancer. The aim of this work is to optimize the labeling condition of Ga-68 with DOTA-[Pro$^1$,Tyr$^4$]-bombesin, an analog of bombesin peptide, through $\textit{in vitro}$ and $\textit{in vivo}$ studies. It was found that the radiolabeled product $^{68}$Ga-DOTA-[Pro$^1$,Tyr$^4$]-bombesin was obtained in high radiochemical purity, ≥98%, without further purification. The results of $\textit{in vitro}$ stability study of radiolabeled compound in phosphate buffered saline, ferric chloride solution and human serum showed that $^{68}$Ga-DOTA-[Pro$^1$,Tyr$^4$]-bombesin was stable for 2 hours. In vitro evaluation of radiolabeled peptide affinity to GRP receptors was performed by a competitive cell-binding assay in the human prostate cancer cell line PC-3 with $^{125}$I-[Tyr$^4$]-bombesin as radiolabel. The calculated IC$_{50}$ of $^{68}$Ga-DOTA-[Pro$^1$,Tyr$^4$]-bombesin with PC-3 cells using GraphPad Prism was in the range of 36-123 nM with the best IC$_5$$_0$ of 66 nM. The uptake of $^{68}$Ga-DOTA-[Pro$^1$,Tyr$^4$]-bombesin from biodistribution study in tumor-bearing nude mice was 3 times higher in tumor than in muscle tissue at 2h post injection.