Abstract: The present invention relates to antibody-drug conjugates comprising (i) an antibody or antigen-binding fragment thereof, (ii) a polymer comprising a particular repeat unit, which is covalently bound to one or more biologically active moieties, such as small molecule drugs, optionally via a linker, and (iii) a polymer-antibody linker moiety which is covalently bound to both the polymer and the antibody or antigen-binding fragment thereof. Additionally, the present invention relates to pharmaceutical compositions comprising the antibody-drug conjugates and to use of the antibody-drug conjugates in medicine.