P0640 Development and characterization of LQ080, a novel extended half-life bispecific TL1A/IL-23 p19 single domain antibody for the treatment of IBD

Abstract Background Despite the effectiveness of current anti-TL1A treatments, unmet needs remain for effective therapeutics for IBD. Therapies simultaneously neutralizing TL1A and IL-23 might be better choices owing to their synergistic anti-inflammatory effects in the pathogenesis of IBD. Methods TL1A and IL-23 single domain antibodies (sdAbs) were selected from immunized sdAb Phage display libraries. A human whole blood-based assay measuring IFNγ secretion was used to assess functional blockade of TL1A. Mouse splenocytes based assay measuring mouse IL-17 release was used to evaluate functional blockade of IL-23. Dextran Sulfate Sodium (DSS) induced mouse bowel inflammatory model was used to judge the in vivo effect of anti-TL1A antibodies. Synergistic anti-inflammatory effect was evaluated in mouse dermatitis model. Half-life extension was measured via pharmacokinetic analysis in non-human primate (NHP) given a single bolus of LQ080 by subcutaneous administration. Results The TL1A sdAb, which binds to both soluble and membrane-bound TL1A in a pH dependent pattern, potently blocked TL1A/DR3 while leaving the TL1A/DcR3 binding undisturbed and illustrated better IFNγ release in human whole blood induced by TL1A than RVT-3101 and PRA023. In DSS model, the TL1A sdAb also demonstrated better anti-inflammation effect than RVT-3101. The TL1A/IL-23 p19 biparatropic sdAb, LQ080, showed better IFNγ secretion inhibition than RVT-3101 and PRA023, and better inhibition of mouse IL-17 induction than Risankizumab and Guselkumab. Synergistic effects were found using LQ080 in both IFNγ release inhibition in human PBMCs induced by IL-23 and TL1A and in the mouse dermatitis model. The half-life of LQ080 significantly extended of 2-3 folds in non-human primate (NHP) compared to that of RVT-3101. Besides, LQ080 did not form large immune complex in vitro when mixed with TL1A and IL-23. Moreover, LQ080 did not stimulate the release of pro-inflammatory cytokines in the cytokines release assay. Conclusion The TL1A sdAb demonstrated better bioactivity than RVT-3101 and PRA023. LQ080, a TL1A/IL-23 p19 biparatropic sdAb, illustrated synergistic anti-inflammation effect both in vitro and iv vivo for its simultaneous neutralization of TL1A/DR3 and IL-23/IL-23R pathways, which would greatly improve the clinical results of IBD patients. The pH dependent TL1A binding makes LQ080 very different from other anti-TL1A mAbs. LQ080 demonstrated extended half-life in NHP making infrequent dosing possible for IBD treatment. No large immune complex formation when mixed with TL1A and IL-23 would make LQ080 safer when administrated by SC route. Overall, LQ080 is a promising TL1A/IL-23 p19 sdAb for IBD treatment.