QL401

QL401 is a bispecific antibody targeting Programmed cell death 1 ligand 1 (PD-L1) and Leukocyte surface antigen CD47, developed by QLSF Biotherapeutics for the treatment of solid and hematological tumors. The molecule is engineered with a PD-L1-binding Fab arm and a CD47-binding scFv arm on a human IgG4 backbone. Its dual mechanism of action involves blocking the PD-1/PD-L1 axis to restore adaptive T-cell activity and inhibiting the CD47/SIRPα 'do not eat me' signaling pathway to promote innate immune phagocytosis by macrophages. Additionally, the IgG4 Fc region is designed to maintain binding to Fc gamma receptors, providing a pro-phagocytic 'eat me' signal. QL401 is specifically engineered to have reduced binding to red blood cells to mitigate potential hematological toxicities while maintaining potent anti-tumor efficacy.