Zenas BioPharma has announced positive findings from its phase 3 INDIGO trial evaluating obexelimab in patients with Immunoglobulin G4-related disease (IgG4-RD), reporting a statistically significant reduction in flare risk and favourable safety outcomes.
The company said the study met its primary endpoint, with obexelimab delivering a 56% reduction in the risk of IgG4-RD flare compared with placebo during the 52-week controlled period.
All four key secondary endpoints were also achieved, including reductions in investigator-assessed flare, fewer flares requiring rescue therapy, higher rates of complete remission and lower cumulative use of rescue medication. Infection rates were lower in the treatment arm and injection site reactions were similar across groups.
Lonnie Moulder, Founder and Chief Executive Officer of Zenas, said: “Given obexelimab’s significant clinical activity and the compelling safety and tolerability profile observed in the INDIGO trial, we believe obexelimab may have an important role as a first line therapy in the long-term management of IgG4-RD.”
He added that the therapy’s mechanism, dosing profile and commercial potential position it as a promising option for patients.
John Stone, Professor of Medicine at Harvard Medical School, said: “Patients living with IgG4-RD have faced limited treatment choices for far too long.” He explained that the results “suggest that obexelimab, with its intriguing mechanism of action – emphasising B cell inhibition rather than B cell depletion – and self-administration by patients, may be an important new therapy for people living with IgG4-RD.”
Lisa von Moltke, Head of Research and Development and Chief Medical Officer of Zenas, said: “These INDIGO trial results build upon the highly positive results observed in our phase 2 MoonStone trial in Relapsing Multiple Sclerosis and further validate obexelimab’s mechanism of action.” She noted the potential for sustained B cell inhibition and highlighted the strength of the clinical dataset.
Zenas plans to submit a Biologics License Application to the FDA in the second quarter of 2026 and a Marketing Authorization Application to the EMA in the second half of 2026.
