Development, formulation and quality evaluation of a lyophilized PSMA-11 kit for rapid radiolabeling with [68Ga]Gallium

 Recently, [68Ga]Gallium lyophilized kit has been widely practiced as it simplifies the radiolabeling process. Thus, our aim is to develop, formulate and evaluate a single-vial lyophilized kit (EZYKit PSMA) for the preparation and radiolabeling of [68Ga]Ga-PSMA-11.

 Two commercially available [68Ge/68Ga] Generators used in this study were from ITG and Eckert & Ziegler with a current [68Ga]Gallium elution activity of 222 MBq and 1480 MBq, respectively. Initially, EZYkit-PSMA radiolabeling parameters were optimized, and the Glass Transition Temperature (Tg) of the optimized PSMA-11 formulation was determined. Quality assessment of EZYkit-PSMA, including physical appearance, quantitative assay of the active ingredient, radiochemical purity, pH, sterility, endotoxin, and storage stability, were also established.

 Optimization of radiolabeling parameters showed that the highest radiochemical purity was achieved with 0.35 ml and 0.75 ml of 1.5 M acetate buffer and 10 µg PSMA-11 for both ITG and Eckert & Ziegler Generator, respectively. The quality assessment results of EZYkit-PSMA were within the specifications except for the physical appearance, where it appears to be structurally collapsed. This study discussed two main factors that contributed to the collapsed lyophilized cake.

 Despite the physical appearance, EZYkit-PSMA was successfully developed, and the quality meets the pharmaceutical standards. EZYkit-PSMA showed high stability over 6 month's storage period in both the fridge and freezer. Overall, using EZYkit-PSMA for radiolabeling with [68Ga]Gallium simplified the whole radiolabeling procedure and reduces process time and error with high labelling yield and efficiency.