The disclosure relates to the engineering of collagen-binding modification of masked therapeutic agents comprising one or more tumor-associated protease cleavage sites. Upon exposure to tumor-associated proteases in the tumor microenvironment, the polypeptide is cleaved, which unmasks the therapeutic agent, reducing off-target side effects and toxicity associated with systemic administration. Accordingly, aspects of the disclosure relate to a polypeptide comprising a therapeutic agent linked to a masking agent through a linker, wherein the linker comprises one or more tumor-associated protease cleavage sites, and wherein the masking agent blocks the association of the therapeutic agent to its therapeutic target, and further wherein the polypeptide is operatively linked to a collagen binding domain or a tumor-targeting agent.