On Oct. 31, 2023, the U.S. Food and Drug Administration (FDA) announced it had approved Amgen’s Wezlana (ustekinumab-auub) as a biosimilar to and interchangeable with Stelara (ustekinumab) for multiple inflammatory diseases.

Wezlana, like Stelara, is approved to treat the following indications: Adult patients with moderate to severe plaque psoriasis who are candidates for phototherapy or systemic therapy; active psoriatic arthritis; moderately to severely active Crohn’s disease; and moderately to severely active ulcerative colitis. Wezlana is also approved for pediatric patients 6 years of age and older with: moderate to severe plaque psoriasis who are candidates for phototherapy or systemic therapy; and active psoriatic arthritis.

Biological products include medications for treating many serious illnesses and chronic health conditions. A biosimilar is a biological product that is highly similar to, and has no clinically meaningful differences from, a biological product already approved by the FDA (also called the reference product).

An interchangeable biosimilar is a biosimilar that has been shown to meet other requirements under the law and may be substituted for the reference product without consulting the prescriber. The substitution may occur at the pharmacy, subject to state pharmacy laws which vary by state, a practice commonly called “pharmacy-level substitution” — similar to how generic drugs are substituted for brand name drugs.

The FDA’s approval of Wezlana is based on a comprehensive review of scientific evidence demonstrating it is highly similar to Stelara and that there are no clinically meaningful differences between the two products in terms of safety, purity and potency (i.e., safety and effectiveness). This evidence included comparisons of the products on an analytical level using an extensive battery of chemical and biological tests and biological assays that confirmed similarity in the structural and functional features of Wezlana and Stelara (including those known to impact safety and efficacy), and comparative human pharmacokinetic data, clinical immunogenicity data, and other clinical safety and effectiveness data. The evidence also demonstrated that Wezlana met the other legal requirements to be interchangeable with Stelara at the pharmacy level.