Zenyaku Kogyo, as Marketing Authorisation (MA) holder, obtained MHLW approval for additional dosage and administration of Rituxan (rituximab) intravenous infusion 100 mg and 500 mg for adult-onset frequently relapsing or steroid-dependent nephrotic syndrome. The approval followed a partial change application filed on June 30, 2025.

An investigator-initiated phase 3 study (IDEC-C2B8-aNS1) evaluating adult-onset frequently relapsing or steroid-dependent patients reported a significantly higher relapse-free rate at week 49 in the Rituxan arm (87.4 percent [95 percent CI: 69.8-95.1 percent]) versus placebo (38 percent [95 percent CI: 22.1-53.8 percent=]; p<0.0001, log-rank test one-sided 2.5 percent significance), indicating a relapse-preventive effect.

The approved regimen for adult-onset cases is 375 mg/m² administered by IV twice at 1-week intervals, followed by a single 375 mg/m² IV dose 6 months after the initial dose. For refractory cases, an alternate regimen of 375 mg/m² IV 4 times at 1-week intervals is described, with a maximum single dose of 500 mg.

Adverse Events (AEs) and Adverse Drug Reactions (ADRs) occurred more frequently in the Rituxan group but were consistent with previously reported safety profiles for approved Rituxan indications in Japan and overseas; no new safety signals were identified. The approval extends an existing body of approvals for pediatric nephrotic syndrome indications to adult-onset frequently relapsing or steroid-dependent disease.