Tumor-localizing activity of porphyrin and its affinity to LDL, transferrin

We spectrochemically analyzed 12 Ga-Metal porphyrins (Ga-Cn-P) with different degrees of hydrophobicity, and observed a close association between the in vivo Ga-Cn-P localization in the tumor and its affinity to transferrin and LDL. Image analysis of tumors with 99m-Tc-STA-R12, a porphyrin-scintigraphic agent, revealed STA-R12 localization in the tumor tissue alone about 1 h after intravenous infusion. Our results suggest the importance of endocytosis mediated by transferrin as well as LDL that have been reported as a mechanism of the tumor-localizing activity of porphyrin.