A biosimilar is a biologic product that is highly similar in composition, potency, and biologic properties to and has no clinically meaningful differences in safety, purity, and potency from the FDA-approved reference product. For a biosimilar to be approved as an interchangeable product, the manufacturer generally conducts clinical trials to prove that the results will be the same if the patient switches between the reference product and the biosimilar. In clinical studies, there were no clinically significant differences in efficacy and safety between Wezlana and Stelara for treatment of moderate to severe plaque psoriasis. The FDA extrapolated approval of Wezlana to psoriatic arthritis, Crohn's disease, and ulcerative colitis based on available data.1-3

According to federal law, an interchangeable product can be substituted for the reference product by the pharmacist without permission from the prescriber. Some states require the pharmacist to notify the prescriber and/or patient before making the substitution; currently four states (AL, IN, SC, and WA) restrict interchangeability entirely.4

Wezlana will be launched in early 2025 when Stelara's patent exclusivity expires. The cost of the drug is not yet available, but will presumably be less expensive than Stelara. The wholesale acquisition cost (WAC) for a 12-week supply of Stelara for treatment of plaque psoriasis for a 75-kg patient is about $13,300 and for treatment of Crohn's disease or ulcerative colitis is about $26,500.5