On July 28, the FDA approved the country’s first interchangeable biosimilar product. Semglee (insulin glargine-yfgn) is both biosimilar to, and interchangeable with, its reference product Lantus (insulin glargine).

Under the Biologics Price Competition and Innovation Act (BPCIA), biological products (e.g., vaccines and therapeutic antibodies) may come to market by showing that they are “biosimilar” to or “interchangeable” with a “reference product,” which is a biological product that has already been approved by the FDA. A biological product is “biosimilar” if it is “highly similar to the reference product notwithstanding minor differences in clinically inactive components” and “there are no clinically meaningful differences between the biological product and the reference product in terms of the safety, purity, and potency of the product.” 42 U.S.C. § 262(i)(2). To date, 28 biological products have been approved as biosimilars.

However, a product that is designated “interchangeable” must meet a more stringent standard: it must be a biosimilar that is “expected to produce the same clinical result as the reference product in any given patient.” 42 U.S.C. § 262(k)(4)(A). And if the product is one that, like insulin, is administered more than once, “the risk in terms of safety or diminished efficacy of alternating or switching between use of the biological product and the reference product [must not be] greater than the risk of using the reference product without such alternation or switch.” 42 U.S.C. § 262(k)(4)(B). FDA guidance has indicated that this latter requirement will usually need to be met with data from a dedicated switching study. See Considerations in Demonstrating Interchangeability With a Reference Product: Guidance for Industry.

The cost of therapeutic biological products has been a focus of much discussion recently, including at the congressional level. Biosimilar products have been slower to take hold in the United States market than in other markets around the world. Although the reasons for that are complex, one factor may be the distinction between biosimilars and interchangeables. The BPCIA contemplates a pharmacist being able to substitute an interchangeable product for a reference product “without the intervention of the health care provider who prescribed the reference product.” 42 U.S.C. § 262(i)(3). A mere biosimilar product, in contrast, must be specifically prescribed by the health care provider. Thus, an interchangeable product is more analogous to a generic pharmaceutical than a biosimilar product is.

Despite that the BPCIA was enacted in 2009, Semglee is the first product to obtain FDA approval as an interchangeable. As the FDA’s press release notes, the availability of an interchangeable product may help increase access and lower the cost of insulin for people with diabetes.

The FDA’s press release is available at https://www.fda.gov/news-events/press-announcements/fda-approves-first-interchangeable-biosimilar-insulin-product-treatment-diabetes.