Distribution of Tetraphenylporphinesulfonate and Tetracarboxyphenylporphine in Tumor-Bearing Mice2

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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.