Spyre Therapeutics Announces Positive Phase 2 SKYLINE Part A Topline

What Happened
Spyre Therapeutics announced on September 8, 2026 (8-K filing) positive 12‑week induction topline results from Part A of its Phase 2 SKYLINE trial for SPY003, an anti‑IL‑23 candidate for moderately‑to‑severely active ulcerative colitis (data cut-off July 27, 2026). In 44 participants through Week 12, SPY003 met the primary endpoint with a statistically significant 10.0‑point mean reduction in the Robarts Histopathology Index (RHI) from baseline (p<0.0001). Other topline efficacy measures included a 20% clinical remission rate, 30% endoscopic improvement rate, and a mean change in modified Mayo Score of –3.5. The trial population was 41% advanced therapy‑exposed, with mean disease duration of 7.1 years and mean baseline RHI 17.2 ± 8.3. Safety was described as consistent with the IL‑23 class: 19 subjects (43%) had any adverse event (AE), 5 (11%) had Grade ≥3 AEs, 3 serious AEs (7%) were reported and deemed not drug‑related, there were no drug‑related SAEs and no deaths.

Key Details

• Primary endpoint: RHI reduction of –10.0 (p<0.0001) in SPY003 (N=44) through Week 12.
• Efficacy rates at Week 12: 20% clinical remission; 30% endoscopic improvement; mMS change –3.5.
• Safety: 43% any AE (n=19), 11% severe AEs (n=5), 7% SAEs (n=3, not drug‑related); one drug‑related AE (2%) that resolved.
• Context & next steps: SPY003 RHI reduction aligns with SPY001 (–9.2) and SPY002 (–10.7); SKYLINE Part B (two monotherapy doses + three high‑dose combination arms: SPY120, SPY130, SPY230) is actively enrolling with topline induction data expected in 2027. Other expected readouts noted: SKYWAY (PsA/axSpA) Q4 2026; SKYLIGHT (HS) late 2027/early 2028.

Why It Matters
The filing reports that SPY003 achieved proof‑of‑concept in Part A and, together with similar results for SPY001 and SPY002, supports Spyre’s stated combination development strategy in inflammatory bowel disease. For investors, the announcement highlights a near‑term clinical catalyst path: Part B enrollment is underway with multiple topline readouts anticipated in 2027 and beyond. The safety summary indicates tolerability consistent with the IL‑23 class and no drug‑related serious adverse events in Part A. The company’s statements are forward‑looking and subject to risks noted in the filing.