Potential use of 52FE porphyrins as tumor scanning agents

Radioiron labelled prophyrins were tested for tumor uptake using tissue culture and animal models. The following porphyrins were tested: hematohemin; protohemin; photo-protohemin; 2-formyl-4-vinyl, 2-vinyl-4 formyl, and 2,4-diformyl deuterohemin derivatives; meso-tetra (4 carbo-xyphenyl) hemin (TCP); tetra-Na-meso-tetra (4-sulfonato-phenyl) hemin (TPPS); and meso-tetra-(4-N-methylpyridyl) hemin tetraiodide (TMPI). ⁵²Fe was produced at TRIUMF by high energy proton spallation of a nickel target. The ⁵²Fe was separated from the other spallation products by solvent extraction with methyl isobutyl acetone and ion exchange chromatography when required. Tissue culture studies using P815 mouse tumor cells showed good uptake with protohemin, TCP, or TMPI. Mouse distribution and excretion studies indicated that the target organ for TMPI was the liver (and spleen) and its biological half-life was 270 days. Animal scans using rats with breast carcenomas with ⁵²Fe labelled protohemin, TCP and TMPI showed no tumor uptake at all. The radiation dose to a human was also calculated.Pharmaceutical Sciences, Faculty ofGraduat