Positron Emitting [68Ga]Ga-Based Imaging Agents: Chemistry and Diversity

Positron Emission Tomography (PET) field and, in particular utilization of 68Ga radiometal is getting momentum. The development of new imaging agents for targeted, pre-targeted, non-targeted imaging and their clinical applications is accelerating worldwide. The pharmacopoeia monographs regarding generator produced 68Ga radionuclide and 68Ga-labeled somatostatin (SST) analogues are in progress. The number of commercial generators and automated synthesizers for 68Ga-labeling chemistry is increasing constantly. Development of a molecular imaging agent is a complex process including identification of the biological target, respective lead compound, synthesis of the imaging agent, its chemical characterization, pre-clinical, and clinical evaluation. The introduction of new radiopharmaceuticals and their accessibility are important factors determining the expansion of clinical nuclear medicine for early disease detection and personalized medicine with higher therapeutic efficiency. Further, the availability of the technology for GMP compliant automated tracer production can facilitate the introduction of new radiopharmaceuticals due to the ability to conduct standardized and harmonized multi-center studies for regulatory approval. This review reflects on the current status of 68Ga in PET field with the focus on the achievements in the chemistry as well as diversity and potential of the resulting tracers. Keywords: Positron emission tomography, 68Ga, radiochemistry, coordination chemistry, conjugation chemistry, radiometal, pharmacopoeia monographs, somatostatin, biological target, lead compound, radiopharmaceuticals, nuclear medicine