Provided is a co-polymer of formula A-B-C or a pharmaceutically acceptable salt thereof, where A comprises a water soluble polymer； B comprises a matrix metalloprotease (MMP)-cleavable polypeptide； C is a chemotherapeutic drug or a derivative thereof； and A is connected to B at a first end through a first covalent bond or a first linking moiety and B is connected to C at a second end through a second covalent bond or a second linking moiety, where the co-polymer is not cross-linked.
