FDA approves ustekinumab-aauz (Otulfi), the fourth ustekinumab biosimilar referencing Stelara, for Crohn disease, ulcerative colitis, moderate to severe plaque psoriasis, and active psoriatic arthritis. Otulfi, developed by Formycon and Fresenius Kabi, was also approved by the European Commission. Due to settlements, Otulfi and other ustekinumab biosimilars will launch no earlier than February 22, 2025.