Zenas BioPharma Presents New Obexelimab Data In Immunoglobulin G4-Related Disease At 6th International Symposium On IgG4-Related Disease

– Phase 3 INDIGO open-label extension findings demonstrated sustained clinical activity of obexelimab –– Additional analyses of secondary endpoints showed that significantly fewer patients experienced clinically meaningful cumulative glucocorticoid toxicity at week 52 –– Initial open-label extension sub-study findings demonstrated vaccine responses following a treatment-free window –– These new findings add to the clinical evidence supporting obexelimab’s investigational role as a reversible, steroid-sparing, B-cell inhibitor for the treatment of IgG4-RD –WALTHAM, Mass., Oct. 12, 2026 (GLOBE NEWSWIRE) -- Zenas BioPharma, Inc. ("Zenas" or the "Company") (NASDAQ:ZBIO), a clinical-stage global biopharmaceutical company advancing therapies for patients living with autoimmune and inflammatory diseases, today announced new obexelimab data in immunoglobulin G4-related disease (IgG4-RD) presented at the 6th International Symposium on IgG4-Related Disease, held October 8-10, 2026, in Cambridge, Massachusetts. The presentations included longer-term flare protection and safety data from the Phase 3 INDIGO open-label extension, initial findings from an associated vaccine response sub-study, and an analysis of glucocorticoid-associated toxicity from the randomized, controlled period of INDIGO.Phase 3 INDIGO Open-Label Extension DataParticipants who completed the 52-week randomized, controlled period of the Phase 3 INDIGO study could enter the open-label extension and receive 250 mg obexelimab subcutaneously once weekly. The open-label extension evaluated longer-term flare protection and safety of continued obexelimab treatment in patients with IgG4-RD.The 12-month probability of remaining flare-free was 0.93 based upon investigator- and adjudication committee-confirmed flares requiring rescue therapy, and 0.87 based upon investigator-determined flares requiring rescue therapy, with five patients pending adjudication at the time of the data cutoff.The median and mean cumulative glucocorticoid rescue doses were 0 mg and 105 mg, respectively.Adverse event rates were comparable to or lower than those observed during the randomized, controlled period. Glucocorticoid-Associated Toxicity ResultsThis Phase 3 INDIGO trial sub-analysis evaluated glucocorticoid-associated toxicity in patients with IgG4-RD using the Glucocorticoid Toxicity Index (GTI).Obexelimab significantly reduced cumulative glucocorticoid toxicity versus placebo at week 52 (GTI Cumulative Worsening Score difference: -11.4; p=0.021).Fewer patients receiving obexelimab reached clinical thresholds for cumulative glucocorticoid toxicity versus placebo.Influenza and COVID-19 Vaccine Sub-Study ResultsInitial analyses from the ongoing sub-study of the INDIGO open-label extension assessed immune responses to vaccination during a planned treatment-free window. In addition, the preservation of pre-existing influenza and SARS-COV-2 immunity following long-term obexelimab exposure was evaluated.Vaccination during the treatment-free window resulted in seroimmunity to influenza in 6 of 7 (86%) participants and seroimmunity to COVID-19 in 4 of 4 (100%) participants.No disease flares were observed during the treatment-free vaccination window, lasting an average of 34.6 days.Participants (n=7) maintained pre-existing markers of immunity following long-term obexelimab treatment (71% for influenza and 50% for COVID-19).