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The changing regulatory requirements for biosimilar drug development: more nuanced than they initially appear

Biosimilars are rising in importance in modern healthcare, offering cost-effective alternatives to biologic medicines and improving patient access to life-saving therapies. However, the regulatory landscape governing their development has been anything but static. In 2025, both the European Medicines Agency (EMA) and the U.S. Food and Drug Administration (FDA) introduced significant changes aimed at streamlining approval processes without compromising patient safety. However, things are not so cut and dry – there is a nuance to the changes by the regulators which must be understood in order to avoid costly mistakes. This article explores these evolving requirements and what they mean for developers.

Background on biosimilar regulation

Historically, biosimilar development has required a rigorous package: detailed analytical comparability, pharmacokinetic (PK) studies, and large-scale confirmatory clinical efficacy trials. These trials, often involving hundreds of patients, were costly and time-consuming, adding years and millions of dollars to development timelines. Yet, mounting evidence suggested that efficacy studies contributed little additional value when analytical and PK data were robust. This insight has driven regulators to rethink their approach. 

EMA’s evolving approach

In April 2025, the EMA published a draft reflection paper signalling a major shift¹. The agency proposed reducing reliance on comparative efficacy trials, instead prioritising advanced analytical characterisation and PK data. The rationale is clear: modern analytical techniques can establish structure–function relationships with high confidence, making large efficacy trials redundant for well-understood molecules2.

The EMA also introduced refinements to submission processes, including modular CTD formatting and enhanced pre-submission engagement³. These changes aim to improve transparency and predictability for applicants. Public consultation on the draft guidance ran until September 2025, with implementation expected in 2026¹. For developers, this means planning strategies that lean heavily on analytical science while maintaining robust safety and immunogenicity monitoring.

FDA’s strategic reforms

In the USA, the FDA unveiled its own draft guidance in October 20254. Like the EMA, the FDA is moving away from mandatory comparative efficacy studies, focusing instead on analytical and PK evidence. A landmark change is the elimination of switching studies for products seeking “interchangeable” status, a requirement long criticised for adding unnecessary complexity and cost⁴.

The FDA’s objectives are ambitious: halving development timelines from 5–8 years to 2–4 years and reducing costs by tens of millions of dollars per product⁵. Additional Q&A guidance from CDER is expected to support smaller developers navigating these reforms. These changes reflect a broader commitment to accelerating biosimilar adoption and reducing healthcare costs in the U.S. market.

EMA vs. FDA: convergence and divergence

Both agencies share a common vision: streamline development, reduce costs and improve patient access. Their convergence lies in prioritising analytical and PK data over large-scale efficacy trials. However, divergence remains. The FDA formalises interchangeability without switching studies, while the EMA avoids central interchangeability designations, leaving substitution policies to member states6,7. Additionally, the EMA places strong emphasis on pre-submission procedures, whereas the FDA focuses on clarifying guidance through CDER updates8.

Impact on industry and developers

For small to mid-sized pharma firms, these reforms are game-changing. Reduced trial requirements lower financial barriers and shorten time-to-market, enabling more players to enter the biosimilar space. However, challenges persist. Requirements remain molecule-dependent, particularly for complex biologics or reference products with multiple mechanisms of action9. Developers must still demonstrate safety and immunogenicity and early dialogue with regulators is critical to avoid missteps.

Patent litigation and market access hurdles also remain, especially in the U.S., where the “patent dance” and inter partes review complexities continue to shape competitive dynamics.

Strategic considerations for developers

Regulatory planning must now be highly tailored. Molecule complexity, therapeutic context, and reference product familiarity will dictate data requirements. Leveraging cross-jurisdiction insights such as oncology or ophthalmology case studies can strengthen submissions. While clinical trial burdens are easing, agencies still expect robust post-marketing safety monitoring, making pharmacovigilance a key component of strategy. 

What the future holds

With EMA implementation targeted for 2026 and FDA guidance expected to finalise soon, biosimilar development is entering a new era and is primed to take advantage of the patent cliff facing blockbuster biological drugs. These changes promise faster approvals, lower costs and broader patient access. For developers, success will hinge on mastering analytical science and engaging proactively with regulators and regulatory experts such as CROs to help navigate the nuances of recent changes and set them up for future success.

References

  1. Streamlining development and assessment of biosimilar medicines. (2025, April). European Medicines Agency (EMA). https://www.ema.europa.eu/en/news/streamlining-development-assessment-biosimilar-medicines
  2. Murovec, V. (2025, June 19). Key takeaways from the EMA’s draft reflection paper on biosimilars. European Pharmaceutical Review. https://www.europeanpharmaceuticalreview.com/article/259680/new-biosimilar-pathways-key-takeaways-from-the-emas-draft-reflection-paper/
  3. EMA Streamlines Procedures for Biosimilar Applications Starting 2025. (2025). Market Access Today. https://marketaccesstoday.com/ema-streamlines-procedures-for-biosimilar-applications-starting-2025/
  4. FDA Moves to Accelerate Biosimilar Development and Lower Drug Costs. (2025, October). U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/fda-moves-accelerate-biosimilar-development-and-lower-drug-costs
  5. Ellenberger, M., & Harston, A. (2025, November 7). FDA Proposes Sweeping Changes to Accelerate Biosimilar Development | JD Supra. https://www.jdsupra.com/legalnews/fda-proposes-sweeping-changes-to-2714019/
  6. Sandle, T. (2025, May 5). EMA Issues Draft Reflection Paper On Accelerating Biosimilar Approval. Clinicalleader.com. https://www.clinicalleader.com/doc/ema-issues-draft-reflection-paper-on-accelerating-biosimilar-approval-0001
  7. Demers, L. A., & Turow, R. (2025, November 4). FDA Policy Changes Could Bring Some Biosimilars to Market Faster. Skadden, Arps, Slate, Meagher & Flom LLP. https://www.skadden.com/insights/publications/2025/11/fda-policy-changes-could-bring-some-biosimilars
  8. Eglovitch, J. S. (2025, August 25). FDA’s CDER announces updated guidance agenda for 2025. Regulatory Affairs Professionals Society (RAPS). https://www.raps.org/news-and-articles/news-articles/2025/8/fda-s-cder-announces-updated-guidance-agenda-for-2
  9. Tuszyner, A. (2025, September 4). The New Era of Biosimilar Development: Seizing the Opportunity Under EMA’s Streamlined Guidelines. Mabion S.A. https://www.mabion.eu/science-hub/articles/the-new-era-of-biosimilar-development/
     
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