The field of the present invention relates to genetically engineered fusion molecules, methods of making said fusion molecules, and uses thereof in anti-tumor immunotherapies. More specifically, the present invention relates to fusion molecule constructs wherein a tumor associated antigen (TAA) antibody (Ab) serves as a targeting moiety to selectively deliver a cytokine to a tumor cell for purposes of killing or inhibiting the growth or proliferation of said tumor cell. In various embodiments, the engineered fusion molecules comprise a TAA Ab fused to an interferon-alpha (IFN-&alpha；) mutant molecule. The engineered Ab-IFN-&alpha； mutant fusion molecules of the present invention demonstrate improved therapeutic index and preserved or increased efficacy as compared to Ab-wildtype IFN-&alpha； fusion molecules, and/or demonstrate improved PK properties as compared to Ab-wildtype IFN-&alpha； fusion molecules.
