Reciprocally masked antibody-cytokine fusion proteins and methods of use thereof

An antibody fusion protein having the following structure:

• (a) a first antigen binding domain comprising a first heavy chain polypeptide (H1) comprising) and a first light chain polypeptide (L1);
• and
• (b) a second antigen binding domain comprising a second heavy chain polypeptide (H2) and a second light chain polypeptide (L2);
• wherein a cytokine is linked via a first protease cleavable linker:
• (i) to an N-terminus of the L1 and/or the L2;
• (ii) to the N-terminus of the H1 and/or H2;
• or
• (iii) to an N-terminus of the L1, L2, H1 and/or H2;
• and
• wherein the first antigen binding domain and the second antigen binding domain are not specific for the cytokine.