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# CDER Biosim. Interchangeability Change Explained
- URL: https://www.fdaweb.com/cder-biosim-interchangeability-change-explained/
- Published: 2024-09-19T12:00:00.000Z
- Updated: 2026-09-14T14:41:46.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5157816

CDER director **Patrizia Cavazzoni** and Office of Therapeutic Biologics and Biosimilars director **Sarah Yim** say a new guidance indicates that a clinical switching study is generally no longer needed to demonstrate interchangeability between a biosimilar and its reference product. Writing in a *JAMA Viewpoint*, the two [say](https://jamanetwork.com/journals/jama/article-abstract/2823807?source=email) that as the accumulated scientific experience pointed in a new direction about a more efficient way to meet the switching standard, FDA changed course.

“Even before issuing our revised guidance, we were able to approve the majority (9/13) of interchangeable products without the need for a clinical switching study, based on application-specific analyses,” Cavazzoni and Yim write. “We will continue to monitor the rapidly growing and changing field of biosimilars, as well as conducting our own research. And we will continue to adapt our scientific and regulatory thinking so that they are in line with the latest science….”