Spyre's SPY002 sets anti-TL1A bar with largest histopathology win in ulcerative colitis

Massachusetts-based Spyre Therapeutics' (Nasdaq: SYRE) extended half-life anti-TL1A antibody SPY002 produced a statistically significant 10.7-point reduction in Robarts Histopathology Index score at Week 12 in moderate-to-severe ulcerative colitis, meeting the primary endpoint of the open-label Part A of the Phase II SKYLINE trial (p<0.0001). The histopathology-first primary endpoint is notable: most UC trials anchor their primary readout to clinical or endoscopic measures, and the 10.7-point RHI reduction is the largest reported for any anti-TL1A antibody in UC to date, positioning SPY002 as a potential leader within its class on this measure. Cross-trial comparisons are limited by differences in study design, patient populations, and the absence of a placebo arm in Part A.

The 48-patient cohort included 35% advanced therapy-exposed participants with a mean disease duration of seven years and a mean baseline RHI score of 16.9 — a moderately to severely affected population. Secondary endpoints showed a 33% clinical remission rate by modified Mayo Score and 42% endoscopic improvement at Week 12. A 3.7-point decline in modified Mayo Score was also observed. These figures are consistent with, or slightly below, what has been reported for first-generation anti-TL1A molecules in early uncontrolled settings, though the RHI reduction appears to exceed prior class benchmarks.

Competitive context

TL1A inhibition has attracted substantial late-stage investment. Sanofi and Teva's duvakitug is in Phase III for UC and Crohn's disease, with Phase IIb maintenance data showing 58% clinical remission at 44 weeks in UC responders. Merck's tulisokibart is also in Phase III. Roche's afimkibart is in Phase III for UC, with a regulatory submission expected by 2027. SPY002's differentiation rests primarily on its extended half-life pharmacokinetics — a roughly 75-day half-life demonstrated in Phase I, more than three times longer than first-generation anti-TL1A antibodies — which Spyre targets for quarterly or semi-annual subcutaneous maintenance dosing. No approved anti-TL1A therapy exists for UC.

SPY002's strategic significance extends beyond its monotherapy profile. Spyre's pipeline thesis is built around combination therapy: Part B of the SKYLINE trial is enrolling three combination arms pairing SPY002 with SPY001 (anti-α4β7) and SPY003 (anti-IL-23), designated SPY120, SPY130, and SPY230. No approved dual-biologic regimen exists for UC, and the company's rationale — that gut-selective integrin blockade combined with cytokine inhibition could produce additive or synergistic mucosal healing — is supported by preclinical colitis models.

Safety in Part A was broadly consistent with the TL1A class. Of 48 patients, 20 experienced treatment-emergent adverse events; two serious adverse events were reported, both judged not drug-related — one UC hospitalization and one worsening of heart failure in a patient with pre-existing cardiac disease. Three drug-related adverse events were recorded (nausea, hypertension, arthralgia), and no drug-related serious adverse events or deaths occurred.

The open-label, uncontrolled design of Part A limits interpretation. These data establish activity and tolerability, but placebo-adjusted treatment effects will only emerge from Part B, where randomized induction data across monotherapy and combination arms are expected in 2027. SPY003 (anti-IL-23) Part A data are expected in Q3 2026, which would complete proof-of-concept for all three monotherapy components ahead of the combination readouts. Spyre reported SPY002's Phase II results within approximately one year of Phase I data — an execution timeline the company characterized as consistent with its operational targets.

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