Skip to main content
DrugPrice

Follow-On Biologic

An informal term for a biologic similar to an already approved innovator biologic, historically used before BPCIA created the formal biosimilar pathway in 2010.

How It Works

Follow-on biologic is largely an obsolete term now superseded by "biosimilar" under the Biologics Price Competition and Innovation Act of 2010. Before BPCIA, there was no FDA pathway for approving a biologic as similar to an existing innovator biologic; manufacturers had to submit complete BLAs with their own clinical trials. A handful of biologic products that were structurally similar to existing products were approved under the old 505(b)(2) NDA pathway (since some older protein products like somatropin and calcitonin-salmon were approved as NDAs, not BLAs), including Omnitrope (Sandoz, growth hormone, approved 2006 as a 505(b)(2) follow-on to Genotropin) and Fortical (calcitonin-salmon, 2005). Once BPCIA implemented the 351(k) biosimilar pathway in 2010, these older follow-on biologics transitioned: on March 23, 2020, the "Deemed to be a License" transition under BPCIA Section 7002(e) reclassified all previously approved NDA-approved biological products (insulin, HGH, etc.) as BLAs, enabling biosimilar competition under 351(k). This was particularly significant for insulin: the transition reclassified Lantus, Humalog, NovoLog, and other insulin analogs as biologics, opening them to the biosimilar pathway. The first interchangeable biosimilar insulin (Semglee, interchangeable with Lantus) was approved shortly after in July 2021. The term "follow-on biologic" is occasionally still used in non-U.S. markets (Japan, Korea) or in older literature to refer to biosimilars generally, but U.S. regulatory usage is now exclusively "biosimilar."

Related Terms

  • Biosimilar, A biologic product that is "highly similar" to an already approved reference biologic, with no clinically meaningful differences in safety, purity, or potency.
  • Reference Product, The FDA-licensed biologic against which a biosimilar is compared and approved under BPCIA, equivalent to the brand-name innovator biologic.
  • 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.

Explore Drug Data

Most Expensive DrugsGeneric Drug WatchSearch All Drugs

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.