Synthesis and in vitro evaluation of a novel radioligand for αvβ3 integrin receptor imaging: [18F]FPPA-c(RGDfK)

The development of RGD-​based antagonist of αvβ3 integrin receptor has enhanced the interest in PET probes to image this receptor for the early detection of cancer, to monitor the disease progression and the response to therapy. In this work, a novel prosthetic group (N-​(4-​fluorophenyl)​pent-​4-​ynamide or FPPA) for the 18F-​labeling of an αvβ3 selective RGD-​peptide was successfully prepd. [18F]​FPPA was obtained in three steps with a radiochem. yield of 44​% (decay cor.)​. Conjugation to c(RGDfK(N3)​) by the Cu(II) catalyzed Huisgen azido alkyne cycloaddn. provided the [18F]​FPPA-​c(RGDfK) with a radiochem. yield of 29​% (decay cor.)​, in an overall synthesis time of 140 min