Optimized Automated Cassette-Based Synthesis of [68Ga]Ga-DOTATOC

Background: [⁶⁸Ga]Ga-DOTATOC is widely used in PET imaging of neuroendocrine tumors (NETs) due to its high affinity for somatostatin receptors. Given the short physical half-life of gallium-68 (~68 min), rapid, reproducible, and GMP-compliant synthesis is essential for clinical application. Methods: An optimized cassette-based automated synthesis protocol was developed using a commercial cassette. Improvements included direct generator elution into the reactor without pre-purification, use of a SepPak^® C18 Plus Light cartridge for purification, replacement of HEPES with 0.3 M sodium acetate buffer (final pH ~3.8), and implementation of a non-vented sterile filter enabling automated pressure-hold integrity testing. Results: Across all batches, the synthesis yielded [⁶⁸Ga]Ga-DOTATOC with high radiochemical purity (> 97%) and reproducible decay-corrected radiochemical yields up to 88.3 ± 0.6%. Total synthesis time was approximately 13 min. The final product remained stable for at least 3 h post-synthesis. The use of acetate buffer eliminated the need for HEPES-specific testing, streamlining the workflow. Automated filter testing improved GMP-compliant documentation and reduced radiation exposure for personnel. Conclusions: This optimized, cassette-based synthesis protocol enables fast, high-yield, and GMP-compliant production of [⁶⁸Ga]Ga-DOTATOC. It supports clinical theranostic workflows by ensuring product quality, process standardization, and regulatory compliance.

DOTATOC; GMP; automated synthesis; cassette-based synthesis; gallium-68; neuroendocrine tumors; radiolabeling.