Bifunctional Agents for Imaging and Therapy

Abstract

Multiple, complementary techniques for tumor detection, including magnetic resonance, nuclear and optical imaging, are under active development; each approach has particular strengths and advantages. Efforts are also currently underway to develop bifunctional agents, so that a single molecule can be used for imaging, therapy, and monitoring the long-term tumor response. This chapter is mainly focused on illustrating the utility of certain tumor-avid photosensitizers in developing agents for tumor imaging [fluorescence, magnetic resonance imaging (MRI), positron emission tomography (PET)] and photodynamic therapy. Recent approaches for developing target-specific agents for photodynamic therapy (PDT) and in vivo tumor imaging are also briefly discussed.

Polyacrylamide-Based Biocompatible Nanoplatform Enhances the Tumor Uptake, PET/fluorescence Imaging and Anticancer Activity of a Chlorophyll Analog

“…To investigate the utility of porphyrin-based compounds in PET/fluorescence imaging and photodynamic therapy,26-28 we synthesized and evaluated a series of 124 I-labeled- compounds related to pyropheophorbide- a and purpurinimides derived from chlorophyll- a . Among the compounds evaluated, methyl 3-( m -iodobenzyloxy)ethyl-3-devinylpyropheo-pheophorbide- a 127 I- PS1 (nonradioactive) and its ( 124 I- PS2 , radioactive) showed the highest potential for both PET/fluorescence imaging29-31 with an option of PDT in mice bearing Colon26 and other tumors (U87, RIF, lung, 4T1 and Panc-1) 32.…”

Multifunctional nanoplatforms for fluorescence imaging and photodynamic therapy developed by post-loading photosensitizer and fluorophore to polyacrylamide nanoparticles

“…6,7 We and others have developed relatively tumor-avid PS which selectively accumulate in tumor, and these molecules have been used to carry optical, PET and MR imaging agents to the tumor sites. 8,9 However, the tumor selectivity of current PS is not always adequate. Approaches that link PS to antibody fragments or receptor ligands have been disappointing because the number of required PS/cell generally is greater than the number of antigen or receptor binding sites.…”