Click Therapy: Novel Concept in Pretargeting Drug Delivery

[1. Basics of Click Therapy] Click therapy is a pretargeted therapeutic strategy that utilizes bioorthogonal click chemistry for treating cancers that overexpress cell surface receptors. In this strategy, pretargeting component and the drug delivery component undergo click reaction on the cell surface. Click chemistry is a concept of rapid and selective reactions between two functional groups under mild, convenient and reliable conditions. This synthetic approach is now widely used in the drug development because of high yielding, wide in scope and producing only byproducts that can be removed without chromatography. Click reactions which can be performed in biological systems without interfering regular biochemical and physiological in the living systems are called bioorthogonal click chemistry. Examples of bioorthogonal click chemistry reactions and their reaction rates are shown in the Fig.1. However, only few click reactions can be used as bioorthogonal click reactions in living systems, since they should be biocompatible, fast and feasible in physiological conditions.