Development of Cancer-targeted Theranostics Probes Based on the Physicochemical Properties of Water-soluble Macromolecules

Water-soluble macromolecules, such as polymers and monoclonal antibodies, have some advantages, including high water solubility, high biocompatibility, a wide range of molecular weights, and amenability to easy modification through the terminal attachment of functional groups. Although there are many instances in which water-soluble polymers are used as solubilizers and stabilizing agents in the medical sciences, the possibility of water-soluble polymers themselves serving as drug carriers in cancer-targeting theranostics (therapeutic + diagnostic) remains to be elucidated. We developed water-soluble polymers labeled with radioisotopes and fluorescence dyes, and elucidated their usefulness as cancer-targeting imaging probes by evaluating their biodistribution with in vivo molecular imaging techniques including nuclear medicine, fluorescence imaging, and photoacoustic imaging. Many water-soluble polymers have some physicochemical properties, such as lower critical solution temperature (LCST), which must be considered as well. We developed cancer-targeting therapeutic compounds by controlling the tumor accumulation of water-soluble polymers based on these physicochemical properties. In this paper, details of the development of cancer-targeting theranostics probes will be discussed.