Introduction

Tumor necrosis factor (TNF)-like ligand 1A (TL1A) mediates a broad spectrum of pro-inflammatory and fibrotic effects and is implicated in the pathogenesis of several immunologic disorders. A pathogenic role for TL1A in IBD is suggested by genetic association. Blockade of the interaction of TL1A with its cognate receptor, DR3, has been shown to ameliorate disease activity in patients with Crohn’s disease (CD) and ulcerative colitis (UC). We have characterized SPY002-091 and SPY002-072, two novel TL1A-specfiic fully human IgG1 monoclonal antibodies (mAbs) with extended pharmacokinetic (PK) half-life. Both antibodies bind soluble and membrane-bound TL1A with high affinity and potently inhibit TL1A-mediated signaling.

Aims & Methods

SPY002-091 and SPY002-072 were evaluated in multiple in vitro and ex vivo assays and compared to other anti-TL1A mAbs in clinical development (MK-7240, RG6631, and TEV-48574). Binding affinity to soluble TL1A was determined by surface plasmon resonance and binding to membrane-bound TL1A was confirmed by flow cytometry (FACS). Competitive blockade of TL1A binding to cell-surface DR3 was determined by FACS, and competition against the decoy receptor, DcR3, was evaluated by ELISA. The binding epitopes of SPY002-091 and SPY002-072 were determined using cryogenic electron microscopy (cryo-EM). TF-1 cell apoptosis and a primary human whole blood-based assay measuring IFNɣ secretion were used to assess functional blockade of TL1A. Half-life extension was measured via pharmacokinetic analysis in cynomolgus monkeys given a single bolus of either SPY002 mAb by intravenous and/or subcutaneous (SC) administration.

Results

SPY002-091 and SPY002-072 each bind to distinct epitopes on TL1A with sub-nanomolar affinity but do not bind the related TNF super family proteins TNF, FasL, TRAIL, or LIGHT. Both antibodies bind soluble TL1A and TL1A expressed on the surface of human embryonic kidney (HEK) cells. Both antibodies potently inhibit TL1A-induced apoptosis in human TF-1 cells and TL1A-induced secretion of IFNɣ in human whole blood, with IC₅₀ values comparable to those of RG6631 and TEV-48574, and a substantially lower IC₅₀ than that of MK-7240.

In cynomolgus monkeys, both SPY002-091 and SPY002-072 exhibit a pharmacokinetic half-life of approximately 25 days compared to an observed half-life of 9-12 days for RG6331 and MK-7240. Structural studies employing cryo-EM show that each SPY002 mAb targets an epitope within a single TL1A subunit enabling binding to both monomeric and trimeric TL1A. Based on allometric scaling of SPY002-091 and SPY002-072 clearance in NHPs, predictive simulations of their human PK properties suggest that Q8W-Q12W SC dosing will achieve therapeutic exposures in patients across a wide range of body weights and albumin concentrations.

Conclusion

We have characterized two anti-TL1A antibodies that exhibit high selectivity and affinity for TL1A, demonstrate effective blockade of the TL1A interaction with DR3, and potently inhibit downstream cellular signaling. With an extended half-life observed in NHP, both SPY002-091 and SPY002-072 demonstrate therapeutic potential for effective and safe treatment of CD and UC with the advantage of infrequent SC dosing. Further preclinical and clinical studies are warranted to demonstrate this potential.

Disclosure

EZ, DR, JM, JM, BK, JO, and HS are employees of Paragon Therapeutics.
JF, DN, AS, and MR are employees of Spyre Therapeutics.