Development of Single Vial Kits for Preparation of 68Ga-Labelled Peptides for PET Imaging of Neuroendocrine Tumours

Purpose

The present work was aimed at the formulation and evaluation of freeze-dried kits of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-peptides for the preparation of ⁶⁸Ga-labelled peptides for PET imaging of neuroendocrine tumours. The ⁶⁸GaCl₃ was obtained from the locally produced nanoceria-PAN, composite-sorbent-based ⁶⁸Ge/⁶⁸Ga generator.

Procedures

Single vial kits of somatostatin analogues DOTA-Tyr³]-octreotide (DOTA-TOC), DOTA-NaI³]-octreotide (DOTA-NOC) and DOTA-Tyr³-Thre⁸-octreotide (DOTA-TATE) were formulated. Optimization of radiolabelling with ⁶⁸Ga from the in-house generator, characterization, long term evaluation of stability of kits and bioevaluation studies in animals was carried out.

Results

DOTA-TOC, DOTA-NOC and DOTA-TATE kits could be successfully formulated. Consistently high radiochemical yields (>95 %) were obtained on radiolabelling with ⁶⁸Ga. The radiolabelled peptides exhibited excellent in vitro stability. Biodistribution studies in normal non-tumour bearing Swiss mice revealed fast clearance of activity via renal route as reported for the respective peptides.

Conclusion

Availability of ready to use DOTA-peptide kits in conjunction with ⁶⁸Ge/⁶⁸Ga generators would pave way for the establishment of ⁶⁸Ga radiopharmacy, a long-felt need of the nuclear medicine community.