Synthesis and biological evaluation of RGD conjugated with Ketoprofen/Naproxen and radiolabeled with [99mTc] via N4(GGAG) for αVβ3 integrin-targeted drug delivery

Background Integrins are interesting targets in oncology. RGD sequence has high affinity for alpha(V)beta(3) integrin receptors. Diagnostic/therapeutic agents can be selectively delivered into cancer cells overexpressing alpha(V)beta(3) integrin by using RGD as a carrier. Nonsteroidal anti-inflammatory drugs (NSAIDs) have shown anticancer properties in in vitro and in vivo studies. The anti-cancer properties of NSAIDs occur though COX-2 inhibition. Regarding the anti-cancer properties of NSAIDs and overexpression of COX-2 enzyme in cancer cells, targeted delivery of NSAIDs into cancer cells to maximize their efficiency and minimize their side effects may gain increased clinical interest. Objectives In this study, RGD was conjugated to ketoprofen/Naproxen to selectively transfer these non-selective COX inhibitors into cancer cells. Methods Keto/Nap-RGD-N4 peptides were synthesized based on solid phase fmoc peptide synthesis. Radiolabeling with [Tc-99m] via N4 (GGAG) ligand was done for biological evaluation. Affinity and specificity of Keto/Nap-RGD-N4 to integrin was determined using A2780, OVCAR-3, SKOV-3 and HT-1080 cell lines. Percentage of Intenalization was measured in A2780 cells. Biodistriburion was studied in normal and tumor model mice. Results Radiolabeled compounds showed high affinity to cells expressing alpha(V)beta(3) integrin in comparison to cells not expressing alpha(V)beta(3). The affinity to A2780 was significantly higher than OVCAR-3 cells. The %internalization into A2780 cells was quite low. Compounds showed more than 50% inhibition on A2780 and OVCAR-3 cells, less than 10% on MCF-7 and HT-1080 cells and no cytotoxicity on fibroblast cells after 48 h incubation. Although uptake of radiolabeled compounds in tumor was high at 1 h post-injection, the tumor/blood ratio was less than 1.5 which made SPECT imaging impossible. Conclusion Provided that NSAID drugs are conjugated to RGD, there will be a selective delivery to target tissues as well as synergetic anti-tumor effects which reduce systemic doses and toxicity. Graphical abstract