FDA's Approval Summary of the First Biosimilar to Natalizumab for the Treatment of Multiple Sclerosis and Crohn's Disease.

The development and approval of biosimilars are imperative for improving patient access to safe and effective treatments. This article summarizes the regulatory approval for Tyruko, the first FDA-approved biosimilar for natalizumab for the treatment of multiple sclerosis and Crohn's disease. Biosimilarity between the proposed biosimilar and the reference product was demonstrated through a comprehensive comparative assessment that included structural and functional characterization, pharmacokinetics (PK)/pharmacodynamics (PD) data, immunogenicity, and safety. The PD assessment incorporated a panel of biomarkers indicative of target engagement and downstream biological responses. The current case underscores the importance of the 351(k) pathway and highlights how the PD-based approach, in conjunction with comparative analytical assessments and PK data, supported the approval of the biosimilar through a study design relying on fewer subjects and a shorter duration compared to an efficacy study.