Zenyaku/Chugai: Rituxan approved in Japan for adult-onset frequently relapsing or steroid‑dependent nephrotic syndrome

Regulatory approval

Zenyaku Kogyo, as marketing authorization 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.

Clinical evidence

An investigator‑initiated Phase III 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% [95% CI: 69.8–95.1%]) versus placebo (38.0% [95% CI: 22.1–53.8%]; p<0.0001, log‑rank test one‑sided 2.5% significance), indicating a relapse‑preventive effect.

Dosing and administration

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 six months after the initial dose. For refractory cases, an alternate regimen of 375 mg/m² IV four times at 1‑week intervals is described, with a maximum single dose of 500 mg.

Safety and clinical context

Adverse events and adverse drug reactions 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.