CTSB and neoplasm: As an application of cathepsin B substrate peptide for the design of albumin-binding prodrugs, Cho et al. developed cathepsin B-overexpressed tumor-cell-activatable albumin-binding doxorubicin prodrug (Al-ProD), constructed with albumin-binding maleimide, cathepsin B-specific cleavable peptide FRRG and doxorubicin (Figure 3A) [216].