Copper-64 labeled sulfophthalocyanines for positron emission tomography (PET) imaging in tumor-bearing rats

Sulfonated metal lophthaloc yanines (PcS) are second generation photosensitizers for photodynamic therapy (PDT) of cancer. Metal-free H,PcS are readily labeled with Cu-64(++) to yield a mixture of sulfonated [Cu-64]CuPcS suitable for biodistribution studies in tumor-bearing rats by positron emission tomography (PET). Most of the Cu-64 activity was sequestrated within the kidneys (20%ID/g) and liver (12%ID/g) while tumor uptake values remained low (0.2%ID/g). Dissection and counting of individual tissue samples after the 24 h scan confirmed the uptake values derived from the PET images. The procedure can be applied to series of novel PcS to evaluate structure-tumor selectivity relationships as a parameter to select potential agents for photodynamic therapy. Copyright (c) 2008 Society of Porphyrins & Phthalocyanines.