Production, quality control, biodistribution assessment and preliminary dose evaluation of [177Lu]-tetra phenyl porphyrin complex as a possible therapeutic agent

Due to interesting therapeutic properties of 177Lu and tumor avidity of tetraphenyl porphyrins (TPPs), 177Lu-tetraphenyl porphyrin was developed as a possible therapeutic compound. 177Lu of 2.6-3 GBq/mg specific activity was obtained by irradiation of natural Lu2O3 sample with thermal neutron flux of 4 × 1013 n.cm-2.s-1. Tetraphenyl porphyrin was synthetized and labeled with 177Lu. Radiochemical purity of the complex was studied using Instant thin layer chromatography (ITLC) method. Stability of the complex was checked in final formulation and human serum for 48 h. The biodistribution of the labeled compound in vital organs of wild-type rats was studied up to 7 d. The absorbed dose of each human organ was calculated by medical internal radiation dose (MIRD) method. A detailed comparative pharmacokinetic study was performed for 177Lu cation and [177Lu]-TPP. The complex was prepared with a radiochemical purity: >97±1% and specific activity: 970-1000 MBq/mmol. Biodistribution data and dosimetric results showed that all tissues receive approximately an insignificant absorbed dose due to rapid excretion of the complex through the urinary tract. [177Lu]-TPP can be an interesting tumor targeting agent due to low liver uptake and very low absorbed dose of approximately 0.036 to the total body of human.