Humira faces significant headwinds as 10 adalimumab biosimilars have launched in the past two years. Although Caremark, a major US pharmacy benefit manager, has removed Humira from its formulary, the drug continues to dominate the adalimumab market, accounting for approximately 80% of the market share. Amgen’s Wezlana, the first approved ustekinumab biosimilar, is anticipated to launch on 1 January 2025. 

There are relatively few drugs in the pipeline for PsA, with many labels being extensions from other indications such as psoriasis.