Fig. 1.

Structure and design of Probody therapeutics. (A) A Probody therapeutic is a monoclonal antibody that contains a light chain extension consisting of a masking peptide (cyan) that blocks the antigen-binding site (yellow), and a protease-specific substrate-containing linker (orange). (B) In the absence of active protease, the Probody therapeutic is functionally masked and cannot effectively interact with target. (C) In the presence of the targeted active protease (green), the linker is cleaved, the masking peptide disassociates, and the Probody therapeutic becomes competent to bind to its target.