Inflammatory arthritis following ustekinumab treatment for psoriasis: a report of two cases.

Psoriasis is a chronic inflammatory skin condition, characterized by T-helper (Th) 1 and Th17 cell activation. Ustekinumab is a fully human immunoglobulin G1κ monoclonal antibody that targets the common p40 subunit that is shared by both interleukin (IL)-12 and IL-23, consequently inhibiting T-cell differentiation along both Th1 and Th17 pathways. This is a report of two patients who developed psoriatic arthritis during ustekinumab treatment for psoriasis. Neither patient had a personal or family history of arthritis.