Spyre Therapeutics' SPY072 misses RA monotherapy bar in SKYWAY Phase 2
Spyre Therapeutics has reported topline data from the rheumatoid arthritis sub-study of its SKYWAY Phase 2 basket trial, announcing that its TL1A antibody SPY072 produced statistically significant improvements over placebo on at least one primary or secondary endpoint at Week 12, but did not reach the company's internal bar to prioritise RA monotherapy development.
Both dose levels achieved target drug concentrations and provided complete suppression of free TL1A through the 12-week readout period, confirming target engagement. The low dose met the primary endpoint, a change from baseline in DAS28-CRP score, with a reduction of 1.9 points versus 1.3 for placebo. The high dose achieved a nominally significant ACR20 response rate of 63% compared to 43% on placebo. The effect size across arms was described by the company as proof-of-mechanism for TL1A inhibition in RA, but insufficient to anchor a monotherapy programme.
The data in detail
The SKYWAY-RA sub-study enrolled approximately 143 participants with moderate to severely active RA who had shown an inadequate response to conventional or advanced therapies. The safety picture was encouraging: adverse event rates were 27% in the SPY072 arms versus 36% in the placebo arm, with infections the most common category. One serious treatment-emergent adverse event occurred on each arm; none were judged drug-related. One participant receiving placebo died during the study.
The results were broadly consistent across advanced-therapy-naive and advanced-therapy-experienced subgroups, which the company considers relevant for its broader autoimmune disease strategy, including potential use of SPY072 as a combination partner rather than as a standalone agent.
Cameron Turtle, chief executive of Spyre, said: "The results today do not lead us to prioritise SPY072 as a monotherapy in RA. However, the favourable safety profile of TL1A inhibition alongside demonstrated efficacy across inflammatory bowel disease, HS, and now RA provide increased conviction that our long-acting TL1A antibodies have potential in a range of autoimmune diseases and as optimal combination components."
Pipeline and competitive context
Spyre now turns attention to the remaining SKYWAY sub-studies. Topline data in psoriatic arthritis and axial spondyloarthritis are anticipated in the fourth quarter of 2026. A combination study of SPY072 with an IL-17A/F inhibitor in hidradenitis suppurativa, under the SKYLIGHT trial, is expected to read out in late 2027 or early 2028. A separate ulcerative colitis programme, SKYLINE Part A evaluating SPY003, is expected as early as September 2026.
The TL1A target has attracted substantial industry attention in recent years. Roche's acquisition of Telavant and the clinical progress of merck's tulisokibart have lifted the class profile considerably, and the RA monotherapy miss from Spyre will be weighed carefully by investors tracking the competitive field. The key distinction lies in whether TL1A inhibition delivers sufficient effect size as a single agent in inflammatory joint disease, or whether its commercial value resides primarily in combination regimens targeting gut and skin indications where the mechanism has shown stronger signals.
Spyre's extended half-life antibody platform is designed to support less frequent dosing, a differentiation the company argues is clinically relevant for patient compliance and combination tolerability. The broader pipeline includes candidates targeting alpha-4-beta-7, IL-23, and IL-17A/F, positioning the company to explore multi-mechanism combinations across a range of inflammatory and autoimmune indications. Whether the RA miss dampens investor appetite ahead of the Q4 2026 data readouts will likely define near-term sentiment around the stock.