TSPO 18 kDa (PBR) Targeted Photosensitizers for Cancer Imaging (PET) and PDT

摘要

Translocator protein (TSPO) 18 kDa overexpression has been ob- served in a large variety of human cancers, especially breast cancers. PK 11195, an isoquinoline analogue, is one of the ligands of highest TSPO binding affinity. Due to the long biological half life ofour photosensitizers, there is a need to label themwith a long lived radioisotope, for example I-124. Our objectives are to find translocator protein targeted photosensitizers for both tumor imaging (PET) and photodynamic therapy (PDT).I-PK11195isconjugatedwiththetumoravidphotosensitizerHPPH.Wefindthat those two tumor avid components complement each other and make the conjugate molecule even more tumor avid; compared to the photosensitizer itself, the conjugate is found to show improved PDTefficacy. It is concluded that I-PK 11195 can be a good vehicle to deliver radionuclide and photosensitizer to TSPO overexpressed tumor regions. Such conjugates could be useful for both tumor imaging (PET)and PDT.