PET imaging utilizing ⁸⁹Zr-labeled human antibody variant and theranostic technologies provided by a novel DDS carrier

“Theranostics”represents a ground-breaking concept of medical modality featuring a hybrid of therapeutic and diagnostic systems. We have recently fabricated a 2 7 kDa single chain variable fragment (scFv, which is essentially a humanized and shortened variant of IgG to establish clinically-applicable PET imaging and theranostics in cancer medicine. A target molecule is mesothelin, a 40 kDa-tumor differentiation-related cell surface glycoprotein antigen, that is frequently expressed by malignant tumors. The theranostics system which comprises of a novel ⁸⁹ Zr-labeled drug delivery system (DDS), derived from novel biodegradable polymeric micelle, “Lactosome”, conjugated with specific scFv, aims to successfully deliver therapeutically effective molecules, such as, apoptosis-inducing small interfering RNA (siRNA), into targeted cells and to offer simultaneous visualization of targets via PET imaging. In particular, the combination of photodynamic therapy (PDT) with 5 -aminolevulinic acid (ALA) and photo-controlled intracellular siRNA delivery system further offers a promising theranostic-based system, ideally via its targeted apoptosis-inducing feature.