Increasing the activity output and optimization of automated radiosynthesis [68Ga]Ga-DOTATATE, [68Ga]Ga-Pentixafor, and [68Ga]Ga-FAPI-64 using two [68Ge]Ge/[68Ga]Ga iThemba generators in series

BACKGROUND: The rapidly increasing clinical demand for 68Ga-labelled radiopharmaceuticals continues to challenge current production capacities, particularly in high-throughput nuclear medicine departments. Although dual-generator concepts have previously been explored, all reported approaches to date have required either pre-purification, fractionated elution, or additional cartridge-based concentration steps, which add complexity and limit routine clinical implementation. In the present study, we report for the first time a fully automated, GMP-compliant synthesis protocol using two iThemba 68Ge/68Ga generators connected in series on a standard EasyOne module applicable to three clinically relevant tracers. We successfully established robust GMP production of [68Ga]Ga-DOTATATE, [68Ga]Ga-FAPI-46, and [68Ga]Ga-PentixaFor without any pre-purification or fractional elution. A key mechanistic finding of this work is the critical role of direct ascorbic acid addition to the reaction medium, which effectively suppresses radiolysis and metal-ion interference under high-activity conditions. RESULTS: We established a Good Manufacturing Practice (GMP)-compliant, fully automated synthesis of [68Ga]Ga-DOTATATE, [68Ga]Ga-Pentixafor, and [68Ga]Ga-FAPI-46 using two 68Ge/68Ga iThemba generators connected in series, of which the older generator is replaced with a new one every 6 months. This configuration enabled elution of maximum activity of 3750 MBq and minimum activity of 2345 MBq, exceeding the elution activity achieved with a single generator by 2300 and 901 MBq respectively. The corrected yield of the labelled products was 91 ± 5% (72 ± 5% non-decay corrected). The additional activity of the labeled products obtained through the two generator configuration enables the examination of 2–4 additional patients per batch and thus resulting in significant cost savings. The direct addition of ascorbic acid to the reaction medium was essential, as it suppressed radiolysis and minimized the impact of metallic impurities. This innovation enabled reproducible labeling without pre-purification, which has not previously been demonstrated with SnO2-based generators. CONCLUSIONS: Dual-generator elution on the EasyOne module without modification of Trasis single-use cassettes provides a robust and scalable approach for high-yield production of 68Ga radiopharmaceuticals. The integration of series-connected iThemba generators with in-situ radiolysis control by ascorbic acid ensures consistent GMP-compliant synthesis of [68Ga]Ga-DOTATATE, [68Ga]Ga-Pentixafor, and [68Ga]Ga-FAPI-46. This method improves production efficiency, reduces costs, and expands clinical accessibility.

Automated radiosynthesis; DOTATATE; FAPI-46; Gallium-68; Pentixafor.