Low-dose obinutuzumab for steroid-dependent nephrotic syndrome complicated by recurrent rituximab-induced serum sickness and anti-rituximab antibodies.

BACKGROUND

Rituximab-induced serum sickness (RISS) is a rare drug complication in patients with steroid-dependent nephrotic syndrome (SDNS).

CASE-DIAGNOSIS/TREATMENT: A 7-year-old boy with SDNS exhibited RISS recurrence 8 days after the third rituximab dose. At that time, the patient's antirituximab antibody (ARA) level was extremely high at > 5000 ng/mg, and his serum rituximab drug level was undetectable at < 0.2 μg/mL. Further, the patient had an early relapse with a short B-cell depletion period after the third rituximab dose. To address ARA-mediated rituximab resistance, a single infusion of obinutuzumab at a dose of 300 mg/m2 was administered. The treatment led to an extended B-cell depletion period of > 6 months and sustained disease remission for 15 months without significant adverse events such as hypogammaglobulinemia and neutropenia.

CONCLUSIONS

Low-dose obinutuzumab can be an effective and safe option for rituximab-resistant SDNS complicated by RISS and the development of ARA.