New Treatment 'Aimabi' for Generalized Myasthenia Gravis Launched

Johnson & Johnson Launches New Drug 'Aimabi' for Generalized Myasthenia Gravis

On November 12, 2025, Johnson & Johnson, known in Japan as Janssen Pharmaceutical K.K., announced the launch of 'Aimabi' (generic name: Nipocalimab) for the treatment of generalized myasthenia gravis (gMG). This marks the first FcRn-inhibiting monoclonal antibody designed for both adults and children above the age of 12, providing a significant advancement in the management of this chronic autoimmune disease.

Key Features of Aimabi

Aimabi is engineered to deliver prolonged symptom control for gMG patients, addressing a high unmet need in the healthcare landscape. It has been shown to rapidly and sustainably reduce the concentration of circulating immunoglobulin G (IgG) antibodies, one of the main causes of gMG, as evidenced by pivotal trials such as Vivacity-MG3. The early results demonstrated that patients receiving Aimabi experienced a significant decrease in IgG levels, sometimes by as much as 75%, within the first 24 weeks of treatment.

Pivotal Trials

In the pivotal Vivacity-MG3 trial, which involved various patients, outcomes highlighted a marked improvement in daily living activities; the aim of the study was to ascertain the effectiveness of Aimabi in combination with standard treatment against a placebo control. Patients in the Aimabi group experienced significant enhancements in critical functions including chewing, swallowing, speaking, and breathing. Follow-up investigations indicated that benefits persisted for up to 72 weeks, showcasing the drug's potential for sustained efficacy.

Moreover, in an ongoing open-label trial for adolescents with positive anti-AChR and anti-MuSK antibodies, results showed a 69% decrease in total serum IgG levels over 24 weeks, corroborating Aimabi's effectiveness across demographics.

Safety Profile

The safety profile of Aimabi has been consistent with existing therapies. In the trials, rates of adverse events (AEs) and severe adverse events (SAEs) were comparable between the Aimabi group and the placebo group, indicating that the introduction of Aimabi does not add extra safety concerns. For instance, approximately 81.6% of patients in the Aimabi combination treatment group experienced AEs, a figure closely aligned with 82.7% observed in the placebo cohort.

Expert Opinions

Reflecting on the introduction of Aimabi, Professor Hiroyuki Murai from the International University of Health and Welfare's Department of Neurology stated, "The advent of Aimabi represents a substantial leap towards addressing the challenges in treating generalized myasthenia gravis, especially as it broadens the scope to include children aged 12 and older. I anticipate that it will substantially improve the daily functions of numerous patients, allowing them to reclaim their everyday lives."

Chris Rieger, President of Johnson & Johnson Innovative Medicine Japan, expressed optimism about the impact of Aimabi: "With the launch of Aimabi, our hope is to transform lives and be a key player in the treatment landscape of generalized myasthenia gravis, accommodating the considerable unmet needs in autoimmune diseases. We are committed to continuous research and development to enhance the quality of life for patients."

Product Overview

- Product Name: Aimabi Intravenous Injection 1200mg & 300mg
- Active Ingredient: Nipocalimab (Recombinant)
- Indications: Generalized myasthenia gravis (in cases where steroids or non-steroidal immunosuppressants are insufficently effective)
- Dosage: Initial dose of 30mg/kg IV infusion, followed by 15mg/kg every two weeks.
- Pricing: Aimabi 1200mg at 1,967,291 yen, and 300mg at 491,823 yen.
- Approval Dates: Manufacturing and marketing authorization granted on September 19, 2025, with drug price listing effective from November 12, 2025.
- Manufacturer: Janssen Pharmaceutical K.K.

Aimabi is expected to reshape the treatment landscape for generalized myasthenia gravis, providing hope and relief to patients and families affected by this debilitating condition. As research continues, it holds the potential to address various autoimmune diseases, paving the way for comprehensive therapeutic strategies in the future.