Development of single vial kits for preparation of (68)Ga-labelled peptides for PET imaging of neuroendocrine tumours.

Objective: 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 (68)Ga-labelled peptides for PET imaging of neuroendocrine tumours. The (68)GaCl3 was obtained from the locally produced nanoceria-PAN, composite-sorbent-based (68)Ge/(68)Ga generator.

Methods: Single vial kits of somatostatin analogues DOTA-[Tyr(3)]-octreotide (DOTA-TOC), DOTA-[NaI(3)]-octreotide (DOTA-NOC) and DOTA-Tyr(3)-Thre(8)-octreotide (DOTA-TATE) were formulated. Optimization of radiolabelling with (68)Ga 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 (68)Ga. 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.

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