VPAC1 Targeted ⁶⁴Cu-TP3805 kit preparation and its evaluation

Area of Science:

• Nuclear medicine
• Radiopharmaceutical chemistry
• Molecular imaging

Background:

• ⁶⁴Cu-TP3805 targets VPAC1 receptors, enabling PET imaging for breast (BC) and prostate cancer (PC).
• Previous work established ⁶⁴Cu-TP3805's potential for human cancer imaging.

Purpose of the Study:

• To formulate and evaluate a freeze-dried diaminedithiol-peptide (N₂S₂-TP3805) kit for ⁶⁴Cu labeling.
• To optimize radiolabeling efficiency and assess the stability of the ⁶⁴Cu-TP3805 complex.

Main Methods:

• Investigated radiolabeling efficiency by varying pH, incubation temperature, and time.
• Assessed long-term kit stability and complex stability in serum using SDS-PAGE.
• Evaluated PET imaging of BC and PC in humans and specificity using digital autoradiography (DAR) on prostate tissues.

Main Results:

• Achieved ≥95% radiolabeling efficiency at pH ~7.2 and 50°C for 90 min.
• Kits demonstrated stability up to 18 months at -10°C; the ⁶⁴Cu-TP3805 complex was stable for 4h at room temperature and showed no transchelation in serum.
• PET imaging of human BC (n=19) and PC (n=26) showed 100% sensitivity; DAR accurately identified malignant lesions and specific prostate tissues.

Conclusions:

• The ready-to-use N₂S₂-TP3805 kit simplifies the routine preparation of ⁶⁴Cu-labeled TP3805 for clinical PET imaging.
• This formulation enhances convenience and reduces day-to-day variability in radiopharmaceutical preparation.