A comparison of routine [68Ga]Ga-PSMA-11 preparation using Locametz and Illuccix kits

Background

Approval of Locametz and Illuccix kits for the manufacture of [⁶⁸Ga]Ga-PSMA-11 (gallium Ga68 gozetotide), a PET imaging agent for prostate cancer, as well as the corresponding therapeutic ([¹⁷⁷Lu]Lu-PSMA-617 Pluvicto), has led to a rapid increase in demand for [⁶⁸Ga]Ga-PSMA-11 PET imaging. Radiopharmaceutical manufacturers, using ⁶⁸Ge/⁶⁸Ga generators, may decide to adopt Locametz and/or Illuccix kits, which requires a comparison to select the most suitable kit for day-to-day use. The objective of this article is to compare both kits and provide guidance for selecting one for routine use, as well as evaluate labeling consistency of both kits during routine production. Additionally, we report our experience during 1.5 years of daily [⁶⁸Ga]Ga-PSMA-11 production at our facility using both kits.

Results

Locametz (n = 181) and Illuccix (n = 256) kits were prepared using non-silicone coated and silicone-coated needles with ⁶⁸Ga activities ranging from 0.53 to 3.16 GBq, with a failure rate of 1 in 128 runs for both kits. With Locametz, a 3.7 GBq generator and 10-min incubation at room temperature gave doses that passed quality control (QC) testing. Use of non-silicone coated needles in the process led to solution discoloration, and QC failure. Additionally, lack of vial inversion led to inconsistent labeling, which improved with subsequent vial agitation. For Illuccix, addition of the acetate buffer to the precursor vial prior to adding the [⁶⁸Ga]GaCl₃ simplifies the workflow. The maximum tolerated activity was 1.85 GBq. Lack of vial inversion led to failures, which were rectified by agitating the vial to properly incorporate the acetate solution with the generator eluate.

Conclusions

Both kits benefited from using a syringe pump to elute the ⁶⁸Ge/⁶⁸Ga generator, vial agitation, and longer length/smaller bore silicone coated needles. Both kits have similar workflows, comparable QC outcomes, and result in equivalent clinical images. Thus, the decision between kits will ultimately be determined by production preferences. Since radiopharmacies have an established “kit-based” workflow, Locametz kits with higher allowed activities and longer shelf-life may offer benefits. Conversely, more traditional PET manufacturing facilities might benefit from using Illuccix kits due to compatibility with cyclotron-produced [⁶⁸Ga]GaCl₃ allowing for kit batching. Ultimately, the commercial availability of 2 approved kits for production of [⁶⁸Ga]Ga-PSMA-11 PET has facilitated ready access to this important new imaging agent.