Radiosynthesis of 18F-(R8,15,21, L17)-vasoactive intestinal peptide and preliminary evaluation in mice bearing C26 colorectal tumours.
BACKGROUND
Radiolabelled vasoactive intestinal peptide (VIP) and its analogues have shown their potential as imaging agents for diagnosing tumours expressing VIP receptor. However, the fast proteolytic degradation in vivo has limited their clinical use.


OBJECTIVE
To prepare the 18F-labelled (R8,15,21, L17)-VIP analogue in a convenient way and to evaluate its potential as an imaging agent for VIP receptor-positive tumours.


METHODS
Radiolabelled (R8,15,21, L17)-VIP was obtained by conjugation with N-succinimidyl 4-([18F]fluoromethyl) benzoate and purified by HPLC. Radiochemical purity and specific radioactivity were measured by analytical HPLC. In-vitro stability of the product was carried out in HSA solution and analysed by HPLC. Biodistribution study was carried out in mice bearing C26 colorectal tumours.


RESULTS
18F-(R8,15,21, L17)-VIP was obtained in greater than 99% radiochemical purity within 60 min in decay-for-corrected radiochemical yields of 21.8+/-4.7% (n=5) and a specific activity of 17.76 GBq x mumol(-1) at the end of synthesis (EOS). Results of in-vitro studies demonstrated a high stability in human serum albumin (HSA) solution. Biodistribution data showed a rapid blood clearance and specific binding towards receptor-positive tumours.


CONCLUSIONS
18F-(R8,15,21, L17)-VIP was prepared by a convenient method. Preliminary biodistribution results showed its potential for imaging tumours over-expressing VIP receptors and encouraged further investigation.
Cheng
Dengfeng
D
Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Sciences, PR China.
Yin
Duanzhi
D
Zhang
Lan
L
Wang
Mingwei
M
Li
Gucai
G
Wang
Yongxian
Y
D000818:Animals; D015179:Colorectal Neoplasms / Q000000981:diagnostic imaging*; D006801:Humans; D007457:Iodine Radioisotopes; D051379:Mice; D008807:Mice, Inbred BALB C; D011877:Radionuclide Imaging; D018005:Receptors, Vasoactive Intestinal Peptide; D014660:Vasoactive Intestinal Peptide / Q000031:analogs & derivatives / Q000138:chemical synthesis*
D007457:Iodine Radioisotopes; D018005:Receptors, Vasoactive Intestinal Peptide; D014660:Vasoactive Intestinal Peptide