Distribution of Tetraphenylporphinesulfonate and Tetracarboxyphenylporphine in Tumor-Bearing Mice2

Abstract

The tumor-localizing potential of the free-base porphyrins tetracarboxyphenylporphine (TCPP) and tetraphenylporphinesulfonate (TPPS₄) was Investigated In DBA/2Ha mice bearing solid L1210 tumors and Ha:ICR mice bearing sarcoma 180 tumors. At certain doses and times after administration, both compounds localized appreciably more in neoplastic tissue than in most other tissues. Maximal uptake of TPPS₄ in tumor tissue was noted by 24 hours, after which its concentration remained constant. TCPP exhibited a maximum concentration in tumors 48 hours post injection followed by a decline through 72 hours. Substantial amounts of TPPS₄ were localized in the kidney at most times and doses studied, whereas TCPP was localized primarily in the lung. Lowering the dose of TPPS₄ did not alter the overall distribution pattern but did improve the tumor:kidney and tumor:tissue ratios. Lower doses of TCPP had the opposite effect. Tumor:lung and tumor:tlssue ratios were decreased in the L1210 tumor system. Tumor: lung ratios also decreased In the sarcoma 180 system, but tumor:tissue ratios increased. The greatest tumor:kidney ratio achieved with the use of TPPS₄ was approximately 2:1 at a dose of 1 mg/kg in the L1210 system. The highest tumor:lung ratio achieved with TCPP was 2:1 at a dose of 10 mg/kg against the sarcoma 180. The substantial extratumor localization of both compounds might restrict their use as tumorvisualizing via fluorescence agents; however, the concentrations of both TCPP and TPPS₄ found in the tumors and the high tumor:muscle ratios found at most doses of TCPP and TPPS₄ suggest that both compounds may be useful as phototherapeutlc agent.