Optimization of PSMA-I&T radiolabeling with <sup>177</sup>Lu<i></i>

Prostate cancer (PCa) is the second most common type of cancer in men and the fifth cause of mortality worldwide. Metastatic prostate cancer is associated with a poor prognosis and decreased life expectancy. Prostate-specific membrane antigen (PSMA) is a type II transmembrane glycoprotein that is anchored in the epithelial prostate cell membrane, overexpressed in prostate cancer, increased in metastatic castration-resistant prostate cancer (mCRPC) patients and with a consensus that its expression level is correlated to the malignancy of the disease. 177 Lu-PSMA-I&T stands out as a promissor radiopharmaceutical for therapy of prostate cancer and currently is being described based on this specifically bind to PSMA with the Glu-urea-Lys pharmacophoric group. This present work aimed to determine the most favorable conditions for labeling PSMA I&T with carried-added lutetium-177, evaluating the influence of molar ratio, pH, temperature and reaction time, to obtain the radiopharmaceutical with high radiochemical purity (%RP ≥95%), avoiding the final purification step. The percentage of radiochemical purity was evaluated by High Pressure Liquid Chromatography (HPLC) and Thin Layer Chromatography on silica gel 60 plate (TLC-SG). The results obtained with this work made it possible to define and standardize the best condition for PSMA I&T radiolabeling with carried-added 177Lu.