APVO451

**APVO451** is a trispecific ADAPTIR-FLEX™ antibody developed by Aptevo Therapeutics for solid tumors expressing nectin-4, such as urothelial, breast, and pancreatic cancers. It simultaneously targets nectin-4 on tumor cells to localize immune activation, engages CD3 on T cells to trigger tumor-killing activity using a proprietary CRIS-7-derived binding domain that minimizes cytokine release syndrome, and binds CD40 on antigen-presenting cells to restore their inflammatory function and overcome immunosuppressive tumor microenvironments. Preclinical data demonstrate local T-cell and APC activation only in the presence of nectin-4-positive tumors, potent tumor cell elimination even under suppressive conditions, and dual immune re-activation superior to standard CD3 bispecific T-cell engagers.[1][3][4]