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 a) mutant molecule. The engineered Ab IFN a mutant fusion molecules of the present invention demonstrate improved therapeutic index and preserved or increased efficacy as compared to Ab wildtype IFN a fusion molecules and/or demonstrate improved PK properties as compared to Ab wildtype IFN a fusion molecules.
