99mTc-D(RGD): molecular imaging probe for diagnosis of αvβ3-positive tumors

Objective Arginine–glycine–aspartic acid (RGD) peptide with its specific binding affinity to integrin αvβ3, is widely investigated for the development of molecular imaging probes for diagnosis of αvβ3-positive tumors. The aim of this work was to evaluate the ability of 99mTc- HYNIC-D(RGD), a novel retro-inverso peptidomimetic derivative for U87MG tumor (αvβ3-positive) imaging. Methods HYNIC-D(RGD) labeled with 99mTc using tricine/EDDA as an exchange coligands. Single-photon emission computed tomography imaging and biodistribution study were performed in nude mice bearing U87MG xenograft tumor. Results The labeling yield was >95%. The radiopeptide showed high uptake value in the U87MG tumor relative to muscle after 2 hours (1.43 ± 0.05 vs. 0.22 ± 0.11 %ID/g). The tumor/muscle ratio was 6.5. Blocking experiment showed specific binding towards tumor. Single-photon emission computed tomography imaging study revealed that radiopeptide had prominent uptake in U87MG tumor. Conclusion The novel 99mTc HYNIC- D(RGD) was demonstrated to be a useful radiotracer for the assessment of αvβ3-positive tumor in animal model. Therefore, further clinical and preclinical studies are required.