Provided are binding polypeptides (e.g., antibodies), and drug conjugates thereof, comprising an Fc domain with an altered glycosylation profile and reduced effector function. In particular embodiment, the Fc domain comprises: an asparagine residue at amino acid position 298, according to EU numbering and a serine or threonine residue at amino acid position 300, according to EU numbering. Also provided are nucleic acids encoding the antigen-binding polypeptides, recombinant expression vectors and host cells for making such antigen-binding polypeptides. Methods of using the antigen-binding polypeptides disclosed herein to treat disease are also provided.