Biologics and biosimilars in musculoskeletal diseases: addressing regulatory inconsistencies and clinical uncertainty

Biologics are complex protein-based medications derived from living organisms, used primarily to treat immune-related diseases. Unlike small-molecule drugs synthesized from chemicals, biologics are produced using advanced biotechnology, making their replication difficult. Biosimilars are nearly identical alternatives to biologics, and they offer a cost-effective option that produces equivalent safety or efficacy outcomes as their reference biologics. Biosimilars are not classified as generic drugs and have a unique regulatory pathway. While biosimilars must demonstrate structural, functional, and clinical similarity to reference biologics, regulatory requirements vary across the US Food and Drug Administration (FDA), the European Medicines Agency (EMA), and the World Health Organization (WHO). The FDA used to mandate clinical studies for interchangeability status, while the EMA and WHO had more flexible approval pathways that enable broader biosimilar adoption. However, the FDA’s approach is evolving, and they may grant interchangeability with scientific justification without separate switching studies. Regulatory inconsistencies extend beyond biosimilars, as batch-to-batch variability in brand-name biologics does not face the same scrutiny as biosimilar approvals. Addressing these regulatory disparities and greater alignment among the FDA, EMA, and WHO may enhance biosimilar adoption. Acceptance of biosimilars may expand treatment accessibility, reduce healthcare costs, and maintain standards of safety and efficacy in managing musculoskeletal diseases.