FDA Approves First Interchangeable Biosimilar for Stelara (Ustekinumab)

The U.S. Food and Drug Administration (FDA) has granted the first FDA ustekinumab approval for an interchangeable biosimilar to ustekinumab (Stelara), a significant development that promises to broaden treatment options for patients with certain autoimmune diseases. This approval allows pharmacists to substitute the ustekinumab biosimilar for the reference product without the need for prescriber intervention, potentially increasing accessibility and affordability.

Drug Overview

Ustekinumab (Stelara) is a monoclonal antibody that targets interleukin-12 and interleukin-23, which are cytokines involved in inflammatory and autoimmune pathways. It is approved for the treatment of several autoimmune diseases, including moderate to severe plaque psoriasis, psoriatic arthritis, Crohn's disease, and ulcerative colitis.

Clinical Insights

Clinical trials for biosimilars, including those for ustekinumab, typically involve pharmacokinetic and pharmacodynamic studies, immunogenicity assessments, and at least one comparative efficacy and safety trial. These trials often focus on sensitive indications such as psoriasis, using primary endpoints like PASI75 (75% improvement in Psoriasis Area and Severity Index) or equivalent disease-specific measures. The safety profile of ustekinumab and its biosimilars includes class-typical adverse events such as increased risk of infections, injection site reactions, and rare hypersensitivity reactions. No unique safety concerns have been identified for biosimilars compared to the reference product.

Regulatory Context

The ustekinumab biosimilar approval followed the FDA's established biosimilar approval pathway, which requires demonstrating that the biosimilar is highly similar to the reference product with no clinically meaningful differences in safety, purity, and potency. The designation of interchangeability requires additional switching studies to ensure there is no increased risk in terms of safety or diminished efficacy when patients switch between the biosimilar and the reference product. This rigorous process typically spans several years.

Market Impact

The approval of an interchangeable biosimilar for ustekinumab is expected to improve market competition and potentially reduce healthcare costs associated with biologic therapies. The interchangeable designation allows for substitution at the pharmacy level without prescriber approval, which can enhance uptake and cost savings. While ustekinumab competes with other biologics targeting IL-17, TNF-alpha, and JAK pathways, its new interchangeable biosimilar may offer a more cost-effective alternative for patients with autoimmune diseases.

Future Outlook

The ustekinumab interchangeable biosimilar approval may pave the way for wider adoption of biosimilars in treating chronic inflammatory diseases. Future developments may include label expansions to cover additional indications and the exploration of combination therapies. The increasing availability of interchangeable biosimilars has the potential to reshape treatment paradigms and improve patient access to essential medications.

Frequently Asked Questions

References

References

1. U.S. Food and Drug Administration. FDA approval. Accessed 2026-04-01.

Dr. Sarah Chen MD, PhD, FACP

Senior Medical Editor

Dr. Sarah Chen is a board-certified internist and former FDA clinical reviewer with 15+ years of experience in pharmaceutical regulatory affairs. She received her MD from Johns Hopkins and her PhD in ...

📅 Published: April 01, 2026