biosimilar

Biosimilars are biological medicines that are highly similar to a licensed reference product. Because biologics are produced in living cells, exact copies are not achievable in the same way as small‑molecule generics. A biosimilar must show no clinically meaningful differences from the reference product in safety, purity, and potency, while maintaining similar mechanism of action and clinical effectiveness. Minor differences in nonfunctional attributes may occur but should not affect performance.

Development follows a stepwise comparability approach. Extensive analytical studies compare structure and function; nonclinical and pharmacokinetic/pharmacodynamic data assess similarity; immunogenicity risk is evaluated. At least one adequately powered clinical trial typically supports similarity in a chosen indication. Regulatory authorities may allow extrapolation of data to other indications of the reference product, provided a scientifically justified rationale.

Regulatory frameworks vary by region. In the United States, the Biologics Price Competition and Innovation Act created a pathway for biosimilars; the FDA can grant biosimilar approval and, in some cases, interchangeable status, which may permit substitution after demonstrating switching safety. In the European Union, biosimilars undergo EMA assessment with data supporting similarity; extrapolation to other indications is common. World Health Organization guidelines provide global expectations for quality, safety, and efficacy. Naming and pharmacovigilance practices differ by jurisdiction and are designed to support traceability and safety monitoring.

Impact and use: Biosimilars can reduce treatment costs and increase access for therapies across oncology and inflammatory diseases. Ongoing pharmacovigilance and postmarketing surveillance monitor safety and effectiveness, and clinicians consider interchangeability, switching, and patient-specific factors when selecting therapy.