Radiosynthesis, Biological Evaluation, and Preclinical Study of a ⁶⁸Ga-Labeled Cyclic RGD Peptide as an Early Diagnostic Agent for Overexpressed α_vβ₃ Integrin Receptors in Non-Small-Cell Lung Cancer

Abstract

The αvβ3 integrin receptors have high expression on proliferating growing tumor cells of different origins including non-small-cell lung cancer. RGD-containing peptides target the extracellular domain of integrin receptors. This specific targeting makes these short sequences a suitable nominee for theranostic application. DOTA-E(cRGDfK)2 was radiolabeled with 68Ga efficiently. The in vivo and in vitro stability was examined in different buffer systems. Metabolic stability was assessed in mice urine. In vitro specific binding, cellular uptake, and internalization were determined. The tumor-targeting potential of [68Ga]Ga-DOTA-E(cRGDfK)2 in a lung cancer mouse model was studied. Besides, the very early diagnostic potential of the 68Ga-labeled RGD peptide was evaluated. The acquisition and reconstruction of the PET-CT image data were also carried out. Radiochemical and radionuclide purity for [68Ga]Ga-DOTA-E(cRGDfK)2 was >%98 and >%99, respectively. Radiotracer showed high in vivo, in vitro, and metabolic stability which was determined by ITLC. The dissociation constant (Kd) of [68Ga]Ga-DOTA-E(cRGDfK)2 was 15.28 nM. On average, more than 95% of the radioactivity was specific binding (internalized + surface-bound) to A549 cells. Biodistribution data showed that radiolabeled peptides were accumulated significantly in A549 tumor and excreted rapidly by the renal system. Tumor uptake peaks were at 1-hour postinjection for [68Ga]Ga-DOTA-E(cRGDfK)2. The tumor was clearly visualized in all images. [68Ga]Ga-DOTA-E(cRGDfK)2 can be used as a peptide-based imaging agent allowing very early detection of different cancers overexpressing αvβ3 integrin receptors and can be a potential candidate in clinical peptide-based imaging for lung cancer.

Preparation and Preliminary Evaluation of Neurotensin Radiolabelled with 68Ga and 177Lu as Potential Theranostic Agent for Colon Cancer

“…Regulatory peptides, such as neurotensin, are suitable agents for specific delivery of radioisotopes to tumour cells, for both diagnostic and therapeutic applications [ 37 , 38 ]. The aim of this study was the investigation of neurotensin as a potential agent used in diagnosis and therapy of colon cancer when coupled with 68 Ga and 177 Lu, respectively.…”

pH-Activatable Cyanine Dyes for Selective Tumor Imaging Using Near-Infrared Fluorescence and Photoacoustic Modalities

“…in A549 cells (Figure 3a, 3b) and ( 2) in a normal cell line, NIH-3T3 cells (Figure S14), which expresses a low level of ABIR. 41 In both cases, substantially decreased fluorescence was observed compared with that by CypHRGD alone in A549 cells. To determine the subcellular localization of CypHRGD after uptake into living cells, we performed confocal imaging (Figure S15).…”

“…We noticed that the fluorescence of the dishes at 4 °C was almost identical to that of negative control dishes without cells, which indicates the extremely low background signal of CypHRGD (Figure S13). To investigate whether the cell internalization of CypHRGD was selectively mediated by the cRGD–ABIR recognition, we carried out control imaging experiments: (1) in the presence of competitive cRGD (100 μM, 10 equiv) in A549 cells (Figure a,b) and (2) in a normal cell line, NIH-3T3 cells (Figure S14), which expresses a low level of ABIR . In both cases, a substantially decreased fluorescence was observed compared with that by CypHRGD alone in A549 cells.…”

Molecular Imaging of Angiogenesis in Oncology: Current Preclinical and Clinical Status

“…Even more octamer peptides have been studied with other isotopes, with similar good-but-not-superior results [ 134 , 135 , 136 ]. Cyclic mono or multimeric peptides, labelled with 68 Ga through a chelator, may also prove to have a future, although a head-to-head clinical comparison is still missing [ 57 , 137 , 138 , 139 , 140 ]. Using the chelator as a positive concept in the RGD structure, some researchers even head back to 18 F and investigate 18 F-labelled NOTA-RGD variants [ 141 ].…”