Successful remission induction of IgG4-related ophthalmic disease by obinutuzumab therapy: a retrospective study of 8 patients

OBJECTIVES: To evaluate the therapeutic efficacy and safety of obinutuzumab in remission induction for IgG4-related ophthalmic disease (IgG4-ROD) patients. METHODS: Eight IgG4-ROD patients were retrospectively enrolled. They were intravenously administered 1000 mg obinutuzumab at baseline and examined for changes in physical signs, orbital structure imaging parameters, IgG4-related disease responder index (IgG4-RD RI), serological index, and adverse events during treatment. The number of treatment sessions was based on treatment response. RESULTS: The mean IgG4-RD RI scores of all patients at baseline (7.75 +/- 2.92) and after treatment (2.00 +/- 0.76) were highly significantly different (P < 0.001). Six patients achieved complete remission (CR) (75%) and two patients achieved partial remission (25%). The mean serum IgG4 levels at baseline (9.45 +/- 6.95 g/L) and after treatment (1.55 +/- 1.09 g/L) showed a mean decrease of 83% (P = 0.0079). The serum IgG4 level correlated well with IgG4-RD RI at baseline and that after each treatment (r = 0.852, P < 0.01; r = 0.78, P < 0.001). In patients with CR, the serum IgG4 levels at baseline correlated positively with dose numbers required for CR (r = 0.86, P < 0.05). Five patients (62.5%) experienced infusion-related reactions (IRRs) during the first obinutuzumab infusion, while only one (12.5%) experienced IRRs during all subsequent eight infusions. CONCLUSION: Obinutuzumab is a safe and promising therapeutic option for IgG4-ROD. It rapidly reduces ocular inflammation and serum IgG4 levels to avoid excessive corticosteroid usage and reduce potential risk of adverse events.