Figure 4. Strategy to improve the PK properties of AMPs adapted from Kelly et al., 2016 [183].

The AMP P18 is amidated at the C-terminus. In addition, it is covalently bound to the protease cathepsin B-sensitive linker for the release of the cancer-active drug; this linker is also covalently attached to a polyethylene glycol (PEG) polymer, which is a hydrophilic moiety that serves as a protective shield from protease degradation and drug clearance.