Japan Approves Anti-CD19 Monoclonal Antibody UPLIZNA for Suppression of Relapse in Immunoglobulin G4-Related Disease (IgG4-RD)
On November 20, 2025, UPLIZNA (inebilizumab), an anti-CD19 monoclonal antibody, received regulatory approval in Japan for the new indication of suppressing relapses in immunoglobulin G4-related disease (IgG4-RD), marking it as the first approved therapy for this indication in Japan.1
This expanded indication is based on the Phase 3, multi-regional MITIGATE study, which provided the clinical efficacy data supporting approval.13
UPLIZNA works by causing targeted and sustained depletion of autoantibody-producing CD19+ B cells, including plasmablasts and some plasma cells, which are key drivers in the pathogenesis of IgG4-RD.13
In the pivotal trial, UPLIZNA demonstrated a significant reduction in risk of disease flare (between 77% and 87% depending on the source), meeting both primary and key secondary endpoints such as annualized flare rate and corticosteroid-free remission.37
IgG4-related disease is a rare, chronic, systemic immune-mediated fibroinflammatory disorder characterized by unpredictable flares, progressive organ impairment, and substantial unmet medical need.13
UPLIZNA is administered as an initial dose, a second dose 14 days later, and subsequently every six months.1
Mitsubishi Tanabe Pharma Corporation is responsible for marketing UPLIZNA in Japan and collaborating internationally with Amgen, the original developer.18
This approval makes UPLIZNA the first and only drug approved specifically for IgG4-RD in Japan, addressing an area previously limited to off-label immunosuppressive therapies such as rituximab.137
Sources:
1. https://www.mt-pharma.co.jp/e/news/assets/pdf/e_MTPC251120.pdf
3. https://www.datamintelligence.com/strategic-insights/igg4-related-disease
7. https://www.citeline.com/-/media/17D10708A4A542A089217CD51AAE3259
8. https://www.amgen.com/newsroom/press-releases/2024/06/amgen-announces-positive-results-for-phase-3-registrational-trial-evaluating-uplizna-inebilizumabcdon-for-treatment-of-immunoglobulin-g4related-disease-igg4rd