Modified N-810 and Methods Therefor

A recombinant protein complex comprising:

• an interleukin-15 (IL-15) domain comprising an N72D mutation (IL-15N72D), a IL-15 receptor alpha sushi-binding domain (IL-15RαSu), an immunoglobulin Fc domain, and a mutated transforming growth factor-beta receptor type 2 (TGFβRII) domain, wherein the mutated TGFβRII domain comprises at least N->Q mutations in positions 47, 71, and 131;
• the IL-15RαSu domain, the Fc domain, and the mutated TGFβRII domain are sequentially linked by amide bonds,
• the IL-15 domain and/or the IL-15RαSu domain comprises a binding domain that specifically binds to a disease antigen, immune checkpoint molecule or immune signaling molecule, and
• wherein the IL-15 domain binds to the IL-15RαSu domain to form the recombinant protein complex.