The U.S. Food and Drug Administration (FDA) has finalized a long-awaited guidance spelling out how biosimilars can achieve an interchangeable status, which means they may be substituted for the reference biologic without a prescriber intervening.

No interchangeable biosimilars have been approved in the U.S. yet, and the number of companies seeking approval for an interchangeable has remained at just one, with Boehringer Ingelheim publicly disclosing that it’s begun an interchangeability study for its adalimumab biosimilar.