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Biosimilar

A biologic product that is "highly similar" to an already approved reference biologic, with no clinically meaningful differences in safety, purity, or potency.

How It Works

Biosimilars are approved under the Biologics Price Competition and Innovation Act (BPCIA) of 2010, codified at 42 U.S.C. 262(k), which created a 351(k) BLA pathway. Approval requires analytical characterization, animal studies, and clinical studies (typically pharmacokinetic/pharmacodynamic plus at least one comparative efficacy trial) demonstrating "no clinically meaningful differences" from the reference product. Typical biosimilar development costs $100-300 million over 8-10 years, far more than the $5-15 million and 2-3 years for a small-molecule generic. This cost structure explains why biosimilar discounts run 15-30% off reference list prices rather than the 80-95% generic discounts. Humira biosimilars launched in January 2023 (Amjevita) with list-price discounts of 5-85% depending on SKU and contracting; net-price savings through rebates are often deeper. By end of 2024, 10+ Humira biosimilars were marketed in the U.S., with prescription volume shifting slowly as PBM formularies updated. Stelara biosimilars launched 2024-2025 (Wezlana, Selarsdi, Pyzchiva), Eylea biosimilars (ophthalmology) began 2024 launches, and Keytruda biosimilars are expected 2028+. The FDA has approved 60+ biosimilars as of 2024 (Purple Book). European biosimilar experience provides roughly two decades of safety and effectiveness data: the EU approved its first biosimilar (Omnitrope) in 2006 and has accumulated extensive post-market surveillance showing equivalent outcomes. Biosimilar uptake in the U.S. was historically slowed by reference-product rebate contracting (rebate walls) and prescriber hesitancy, but 2024 data show accelerating adoption.

Related Terms

  • Biologic Drug, A complex medication derived from living cells, including monoclonal antibodies, vaccines, and cell therapies, that treats serious conditions like cancer and autoimmune diseases.
  • Biosimilar Interchangeability, An FDA designation under BPCIA allowing a biosimilar to be substituted for the reference biologic at the pharmacy without prescriber consultation, requiring additional switching studies.
  • Reference Product, The FDA-licensed biologic against which a biosimilar is compared and approved under BPCIA, equivalent to the brand-name innovator biologic.
  • Patent Cliff, A sharp drop in a drug's revenue when its patent expires and generic competitors enter the market, often cutting prices by 80% or more.

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About This Definition

This definition is part of the DrugPrice Drug Pricing Glossary, 49 terms explaining how prescription drug pricing works in the United States. All definitions are written in plain language for patients, caregivers, journalists, and healthcare professionals.

this entity is one of the U.S. Medicare prescription-drug pricing concepts that recurs across this site. The definition above is the technical answer; the paragraphs below add the practical context for how the concept connects to the CMS Medicare Part D Drug Spending data data behind every per-entity page on the site.

In the CMS Medicare Part D Drug Spending data data, this concept shapes one or more of the fields that drive the per-entity grades and rankings on this site. The methodology page describes which fields feed into which output; this glossary entry documents the underlying term.

Source: CMS Medicare Part D Spending, 2026.