According to some embodiments, methods for covalently or non-covalently conjugating an antibody (e.g., hu3S193 or other humanized antibody) or functional fragment thereof with an siRNA molecule (e.g., anti-STAT3 siRNA) is provided. Such methods may include (1) modifying an antibody or functional fragment thereof with a linker to provide a linker-modified antibody, combining a target siRNA with a disulfide containing aldehyde linker to provide a linker-modified target siRNA and combining the linker-modified target siRNA with linker-modified antibody to form an antibody-siRNA complex or (2) modifying an antibody or functional fragment thereof with a (Arginine)9 peptide to form an antibody-9R complex and associating an siRNA molecule with the antibody-9R complex to form an electrostatic antibody-9R:siRNA complex. In another embodiment, an antibody-siRNA conjugate may be used in methods for suppressing or silencing STAT3 protein expression in a cancer cell.
