Interchangeability Is Finally a Reality

In a long-awaited first, the Food and Drug Administration has approved Viatris’ biosimilar insulin candidate Semglee® as interchangeable, meaning it can be substituted automatically at the pharmacy if the prescription is written for the reference product Lantus®. As allowed by individual state laws, substitution does not require the pharmacy to notify a prescriber.

This marks the first interchangeable biosimilar approval of any type in the US. The nonproprietary name given for Semglee is insulin glargine-yfgn. It is approved for use for any approved glargine indication.

In the FDA’s press release announcing the approval, Acting Commissioner Janet Woodcock, MD, stated, “This is a momentous day for people who rely daily on insulin for treatment of diabetes, as biosimilar and interchangeable biosimilar products have the potential to greatly reduce health care costs. Today’s approval of the first interchangeable biosimilar product furthers FDA’s longstanding commitment to support a competitive marketplace for biological products and ultimately empowers patients by helping to increase access to safe, effective and high-quality medications at potentially lower cost.”

The FDA specifies that an approved interchangeable biosimilar can be expected to produce the same clinical result as the reference biologic in any given patient. The patient should not experience any addition risk in terms of safety or lower efficacy than if the patient continued to receive the reference product.

Something that may get lost in this momentous announcement is that the approval of Semglee also marks the first approval of a biosimilar insulin in the US. This is a bit of a misnomer, however. Earlier copies of insulin glargine (e.g., Basaglar®) were approved under the 505(b)2 pathway before the March 2020 transition to 351(k) approval. Like Basaglar, Semglee was originally approved (in June 2020) under the 505(b)2 pathway and launched in the US in August 2020. However, Viatris (then Mylan) decided to file for biosimilar status, likely in the hope of securing the interchangeability designation. At the time of last year’s launch, partners Biocon and Mylan indicated that it would discount the price of Semglee by 65% (a wholesale acquisition cost of $147.98 per package of five pens holding 3 mL each) compared with the 2020 price of Lantus.

Viatris is also working on a biosimilar of insulin aspart. The 351(k) application for this product is expected to be submitted before the end of the year.

The next FDA decision on interchangeability is likely that for Boehringer Ingelheim’s adalimumab biosimilar Cyltezo®.

The value of interchangeability, both to payers and to manufacturers, is not yet known. It should provide some leverage for plans who want to quickly shift marketshare from a reference product, allowing them to maximize anticipated cost savings. Yet, the insulin glargine space already has several brand-name competitors; it will be interesting to see whether the new interchangeable entering the market moves the needle on insulin glargine pricing or biosimilar uptake. Since Semglee was already available and the list price heavily discounted, this may tamp down the reaction by payers.

From the perspective of the adalimumab marketplace, the value of interchangeability seems cloudier, because of the sequential launch of biosimilars entering settlements with AbbVie, and the presence of two biosimilars who may decide to launch even earlier.

In any case, this has been a very long slog to reach this first. Enough speculating. Let’s see what really happens.

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