Development and evaluation of improved in-house procedure for radiolabelling of theranostic agent [¹⁷⁷Lu]Lu-PSMA-617

Recent focus in the treatment of prostate cancer is directed towards the development and application of theranostic agents such as [¹⁷⁷Lu]Lu-PSMA-617. It combines a PSMA-specific peptidomimetic with a therapeutical radionuclide ¹⁷⁷Lu and it is used in radioligand therapy that selectively delivers ionizing radiation into tumor cells. This study reports the automated radiosynthesis and quality control of an in-house [¹⁷⁷Lu]Lu-PSMA-617 preparation and a direct comparison of its properties with the reference product (Pluvicto^®).

The radiopharmaceutical was obtained with > 95% radiochemical purity and > 96% radiochemical yield. The addition of ethanol improved radiochemical yield. The obtained product maintained > 98% radiochemical purity for up to 72 h in isotonic saline and human serum at 25 °C and 37 °C. The use of carrier-added ¹⁷⁷Lu for the in-house product and non-carrier-added ¹⁷⁷Lu for the reference product was confirmed by ICP-MS and gamma spectrometry methods.

Comparative quality control demonstrated generally equivalent quality attributes of in-house prepared product and the reference product, supporting in-house product suitability for routine clinical application at activities up to 7.4 GBq. This experiment showed that in-house production of ¹⁷⁷Lu-labeled theranostics is cost-effective method and can be automatized resulting in high quality and efficient production.