Spyre Therapeutics drug cuts ulcerative colitis activity, shares surge 34.5%

Spyre Therapeutics said its experimental ulcerative colitis drug SPY001 met the main goal in a mid-stage study, a result that sent the company’s shares up 34.5% as investors looked past a routine trial update and toward a possible new option in a crowded but still difficult treatment field.

The Phase 2 SKYLINE Part A trial enrolled 43 patients with moderately to severely active ulcerative colitis. At week 12, SPY001 produced a statistically significant 9.2-point reduction in the Robarts Histopathology Index, a measure of bowel inflammation and tissue damage. Spyre also reported 40% clinical remission by modified Mayo Score and 51% endoscopic improvement, signals that the drug did more than trim lab markers and showed activity patients and doctors can see in symptoms and scope findings.

Those numbers matter because ulcerative colitis is not a niche condition. The CDC estimates inflammatory bowel disease affects roughly 2.4 million to 3.1 million people in the United States, and the National Institute of Diabetes and Digestive and Kidney Diseases describes ulcerative colitis as a chronic inflammatory bowel disease driven by abnormal immune activity that inflames and ulcers the large intestine. For patients, that can mean repeated flares, pain, fatigue and long stretches of disruption to work, school and daily life, which is why even modest-looking efficacy gains can draw strong attention.

Spyre said SPY001 was well tolerated and that its safety profile was consistent with the α4β7 class. The only serious adverse event reported in coverage was chest pain in a 68-year-old man with preexisting cardiovascular disease, and investigators judged it unrelated to treatment. The company held a conference call at 8:00 a.m. ET to discuss the data, and it said recruitment for SKYLINE Part A had closed while Part B monotherapy and combination cohorts were opening.

The readout is still only a step in the drug-development pipeline. Spyre said additional Part A data for SPY002 are expected in mid-2026 and SPY003 in the third quarter of 2026, with Part B induction data due in 2027. That leaves the company with more work before any approval filing, including larger and longer trials that must confirm durability, safety and real-world benefit.

Even so, the benchmark is clear. Spyre has framed SPY001 as an α4β7 antibody designed to improve on Takeda’s Entyvio, which first won FDA approval in May 2014 and later gained U.S. approval for subcutaneous maintenance dosing in September 2023. Mizuho analysts said the data supported the idea that higher exposure than vedolizumab may be translating into better efficacy. If later studies hold up, Spyre says the drug could support quarterly or biannual dosing and potentially serve as a backbone for combinations with SPY002, an anti-TL1A drug, or SPY003, which targets IL-23.