Production and Evaluation of Lutetium-177 Maltolate as a Possible Therapeutic Agent

Development of oral therapeutic radiopharmaceuticals is a new concept in radiopharmacy. Due to the interesting therapeutic properties of 177Lu and oral bioavailability of maltolate (MAL) metal complexes, 177Lu-maltolate (177Lu-MAL) was developed as a possible therapeutic compound for ultimate oral administration. The specific activity of 2.6-3 GBq/mg was obtained by irradiation of natural Lu2O3 sample with thermal neutron flux of 4×1013 n.cm-2.s-1 for Lu-177. The product was converted into chloride form which was further used for labeling maltol (MAL). At optimized conditions a radiochemical purity of about >99% was obtained for 177Lu-MAL shown by ITLC (specific activity, 970-1000 Mbq/mmole). The stability of the labeled compound as well as the partition coefficient was determined in the final solution up to 24h. Biodistribution studies of Lu-177 chloride and 177Lu-MAL were carried out in wild-type rats for post-oral distribution phase data. Lu-MAL is a possible therapeutic agent in human malignancies for the bone palliation therapy so the efficacy of the compound should be tested in various animal models.