Latikafusp (AMG 256) is a bifunctional fusion protein comprising a PD-1-targeting antibody and IL-21 mutein designed to deliver IL-21 pathway stimulation to PD-1+ cells. Latikafusp is designed to prime and extend the activity of cytotoxic and memory T cells and induce anti-tumor immunity. Latikafusp has the potential for solid tumors research.