Enhanced in-vivo persistence and PET imaging performance of [⁶⁸Ga]Ga-DOTA-TMVP1446/GS5 as a VEGFR-3 radiotracer

Vascular endothelial growth factor receptor-3 (VEGFR-3) is overexpressed in tumor-induced lymphangiogenesis. TMVP1446/GS5 is a peptide analogue specifically targeting VEGFR-3, developed through substitution of the original peptide TMVP1446 with non-natural amino acids and terminal modification. This study aimed to evaluate the potential of ⁶⁸Ga-labeled TMVP1446/GS5 as a probe for imaging primary tumors and metastatic lymph nodes.

[⁶⁸Ga]Ga-DOTA-TMVP1446/GS5 exhibited excellent labeling yield and radiochemical purity (RCP). Radio-HPLC analysis demonstrated comparable radiochemical and chemical stability to the original probe. Although stability in mouse plasma remained limited, [⁶⁸Ga]Ga-DOTA-TMVP1446/GS5 exhibited modestly improved metabolic stability than the original probe. Cellular assays and surface plasmon resonance (SPR) analysis showed comparable or slightly higher binding affinity to VEGFR-3 relative to the original probe. In B16F10 subcutaneous xenografts, [⁶⁸Ga]Ga-DOTA-TMVP1446/GS5 showed stronger and more sustained tumor uptake compared to the original probe, along with extended in vivo retention. At 2 h post-injection, tumor uptake reached 4.90 ± 0.36%ID/g, approximately five times of the original probe (1.03 ± 0.06%ID/g). In B16F10 footpad lymph node metastasis model, [⁶⁸Ga]Ga-DOTA-TMVP1446/GS5 enabled clear visualization of metastatic lymph nodes.

[⁶⁸Ga]Ga-DOTA-TMVP1446/GS5 showed enhanced and sustained tumor uptake and extended in vivo retention. It provided relatively superior imaging of both primary tumors and metastatic lymph nodes at later time points, suggesting its potential for further research.