A Novel Dual-targeting PD-1 and TL1A Bispecific Antibody with Synergistic Effect for Immune Disorders Treatment 2255198

Abstract Introduction Programmed cell death protein 1 (PD-1), an inhibitory immune checkpoint on T cells, maintains immune homeostasis. Dysregulated PD-1 signaling is implicated in autoimmune pathogenesis, whereas insufficient activity may result in uncontrolled T-cell responses. TNF-like ligand 1A (TL1A), a member of the TNF superfamily, engages DR3 to activate NF-κB pathway, thereby amplifying pro-inflammatory cytokine production and contributing to chronic inflammation and fibrosis. We developed a novel bispecific antibody that co-targets PD-1 and TL1A to achieve synergistic inhibition of pathogenic immune activation, with relevance to both PD-1 and TL1A driven immune disorders. Methods Bispecific antibodies were generated by fusing novel PD-1 agonistic and TL1A antagonistic VHH domains in a tetra-valent format. A series of candidates were evaluated through comprehensive in vitro assays including assessment of binding kinetics, PD-1/PD-L1/2 blocking, PD-1 agonism, TL1A-DR3 blocking, ADCC, and T-cell suppression. In vivo efficacy was assessed in a mouse colitis model. Results The leading bispecific antibody binds to a unique PD-1 epitope, enhances PD-1—PD-L1/2 engagement, and inhibits TL1A—DR3 binding. It demonstrated dose-dependent PD-1 pathway agonism and TL1A antagonism, suppressing T-cell activation, proliferation and cytokine production. Robust ADCC activity against PD-1+ T cells was observed. In vivo, it showed superior efficacy over comparator monotherapies in ameliorating colitis. Conclusion The anti-PD-1xTL1A bispecific antibody exerts synergistic immunomodulation through three complementary mechanisms: enhancement of PD-1 inhibitory signaling, blockade of the TL1A—DR3 pathway, and selective depletion of PD-1-expressing T cells via ADCC. It significantly mitigates T-cell-driven inflammation in vitro and ameliorates disease activity in vivo, supporting its potential as a novel treatment for autoimmune diseases such as IBD (inflammatory bowel disease). Funding Source Nanjing Leads Biolabs Co., Ltd Topic Categories Therapeutic Approaches to Autoimmunity (THER)