Cathepsin B as a target in cancer therapy and imaging

Cysteine cathepsins are important proteases that play important roles in physiological and pathological processes and have the potential to be target candidates for disease diagnosis and treatment. Among the 11 proteases within the cathepsin family, cathepsin B (CTB) has received the most attention as it is upregulated across a variety of cancers, and has been shown to be closely related to the development and metastasis of cancer. Therefore, CTB has become increasingly recognized as a promising target in tumor imaging and cancer treatment. For instance, imaging tools that target CTB can help us distinguish tumor boundaries that guide surgical navigation, early diagnosis of tumors, and help us gain insight into the specific role that CTB plays in the complex environment of tumor hydrolase. With regard to cancer treatment, pro-drugs and other target therapeutic agents that respond to CTB have been proposed and used in clinical studies, and some of them are already on the market. This brief review refers to the recent advances of CTB in the imaging area and cancer treatment, and indicates the great potential of CTB as a biomarker in the field of cancer-related research.