Obexelimab reduces IgG4-related disease flares

Weekly obexelimab reduced flares and steroid exposure in active immunoglobulin G4-related disease.
*Phase 3 double-blind randomized controlled trial; Level 1b (OCEBM).

Citation

Della-Torre E, Baker MC, Zhang W, et al. Obexelimab for the Treatment of IgG4-Related Disease. N Engl J Med. 2026;395:1273-1284. doi:10.1056/NEJMoa2601337

Background

Immunoglobulin G4-related disease can damage many organs and often relapses after steroids are stopped. Long-term steroid use is harmful, so steroid-sparing treatments are needed.

Patients

194 adults with active immunoglobulin G4-related disease requiring steroid treatment. Key exclusions included active infection, prednisone-equivalent dose above 60 mg daily within 4 weeks, and recent B-cell-depleting or other immune-modifying therapy within 6 months.

Intervention

Obexelimab 250 mg by weekly under-the-skin injection for 52 weeks, after steroid induction and taper to discontinuation by week 8.

Control

Matching placebo with the same steroid induction and taper schedule.

Outcome

Flare requiring rescue treatment, complete remission, rescue steroid dose, and steroid toxicity score (0 to 410; higher is worse).

Follow-up Period

52 weeks.

Results

Outcome Obexelimab Placebo Effect
First flare needing rescue therapy (primary) 26.8% 54.6% Hazard ratio 0.44 (95% CI 0.28 to 0.71); NNT 4
Annualized flares needing rescue therapy 0.34/year 0.70/year Rate ratio 0.48 (95% CI 0.32 to 0.74)
Complete remission at week 52 37.1% 19.6% Risk difference 17.7 points (95% CI 5.4 to 30.0); NNT 6
Cumulative rescue steroid dose 329.5 mg 929.8 mg Mean difference −600.3 mg (95% CI −1011.1 to −189.5)

CI = confidence interval; NNT = number needed to treat.

Efficacy analyses were intention-to-treat. This was not a noninferiority trial. The steroid toxicity score has a 15-point minimally important difference; the observed 11.4-point benefit was below that threshold.

Limitations

Follow-up was limited to 52 weeks, so long-term safety, durability, and cost-effectiveness remain uncertain. The comparator was placebo, not another approved steroid-sparing treatment. The sponsor designed and funded the trial, and some authors were employees. Racial and regional imbalances may limit generalizability. Possible indication creep: evidence comes from active disease requiring steroids, mostly with multiorgan involvement.

Funding

Zenas BioPharma; sponsor involvement raises potential bias concern.

Clinical Application

Consider obexelimab for steroid-sparing maintenance in active immunoglobulin G4-related disease, pending access, long-term safety, and comparison with existing options.