MBS309

MBS309 is a PD-1-targeted, alpha-biased interleukin-2 (IL-2) bispecific fusion protein developed by Beijing Mabworks Biotech. It consists of an alpha-biased IL-2 variant fused to the C-terminus of the anti-PD-1 monoclonal antibody pembrolizumab. The molecule is designed to enhance the safety and therapeutic window of IL-2 by achieving cis-engagement, specifically delivering IL-2 signals to PD-1-high and CD25-high CD8+ T cells within the tumor microenvironment while reducing systemic toxicity. Preclinical studies indicate robust anti-tumor activity in models resistant to PD-1 inhibition and a favorable safety profile compared to non-targeted IL-2 variants.