An assembly for a drug delivery device comprising: - a cartridge containing a plurality of doses of a drug, - a piston rod adapted and arranged to expel drug from the cartridge during a dose delivery operation of the assembly, the piston rod comprising a thread, - a nut member, wherein the nut member is adapted and arranged to be rotated with respect to the piston rod about a rotational axis during a dose setting operation of the assembly, the nut member thereby being axially displaced along the piston rod from a start position towards an end position with respect to the piston rod due to mechanical cooperation of the nut member with the thread, - a last dose stop mechanism adapted and arranged to prevent a user from setting a dose of the drug which exceeds a remaining amount of drug in the cartridge, the last dose stop mechanism comprising at least one first interaction member and at least one second interaction member provided by the piston rod and at least one first stop member and at least one second stop member provided by the nut member, wherein the interaction members (16, 17) and the stop members (18, 19) are configured to engage with one another when the nut member is in the end position with respect to the piston rod such that further relative movement of the nut member and the piston rod for setting a dose of the drug is prevented, wherein the last dose stop mechanism comprises a radial end stop, wherein the first stop member and the first interaction member each comprise at least one radial stop face, wherein the radial stop faces are configured to mechanically cooperate with one another when the nut member is in the end position with respect to the piston rod such that further rotation of the nut member with respect to the piston rod for setting a dose of drug is prevented, and characterised in that the last dose stop mechanism further comprises an axial end stop, wherein the second stop member and the second interaction member each comprise at least one axial stop face, wherein the axial stop faces are configured to mechanically cooperate with one another when the nut member is in the end position with respect to the piston rod such that further axial movement of the nut member with respect to the piston rod for setting a dose of drug is prevented. - a cartridge containing a plurality of doses of a drug, - a piston rod adapted and arranged to expel drug from the cartridge during a dose delivery operation of the assembly, the piston rod comprising a thread, - a nut member, wherein the nut member is adapted and arranged to be rotated with respect to the piston rod about a rotational axis during a dose setting operation of the assembly, the nut member thereby being axially displaced along the piston rod from a start position towards an end position with respect to the piston rod due to mechanical cooperation of the nut member with the thread, - a last dose stop mechanism adapted and arranged to prevent a user from setting a dose of the drug which exceeds a remaining amount of drug in the cartridge, the last dose stop mechanism comprising at least one first interaction member and at least one second interaction member provided by the piston rod and at least one first stop member and at least one second stop member provided by the nut member, wherein the interaction members (16, 17) and the stop members (18, 19) are configured to engage with one another when the nut member is in the end position with respect to the piston rod such that further relative movement of the nut member and the piston rod for setting a dose of the drug is prevented,