Which agent is an IL-12/23 inhibitor used in psoriatic arthritis?

Which agent is an IL-12/23 inhibitor used in psoriatic arthritis?

• A. Brodalumab
• B. Ixekizumab
• C. Ustekinumab
• D. Secukinumab

Answer: (C)

Understanding IL-12/23 inhibitors requires recognizing that IL-12 and IL-23 share a common p40 subunit. Ustekinumab is a monoclonal antibody that targets this p40 subunit, blocking both IL-12 and IL-23 signaling. By inhibiting these pathways, it reduces the activity of Th1 and Th17 cells, which are drivers of inflammation in psoriasis and psoriatic arthritis. That makes ustekinumab effective as an IL-12/23 inhibitor in psoriatic arthritis. In contrast, the other agents target IL-17A or the IL-17 receptor rather than IL-12/23, so they do not belong to the IL-12/23 inhibitor class.

Understanding IL-12/23 inhibitors requires recognizing that IL-12 and IL-23 share a common p40 subunit. Ustekinumab is a monoclonal antibody that targets this p40 subunit, blocking both IL-12 and IL-23 signaling. By inhibiting these pathways, it reduces the activity of Th1 and Th17 cells, which are drivers of inflammation in psoriasis and psoriatic arthritis. That makes ustekinumab effective as an IL-12/23 inhibitor in psoriatic arthritis.

In contrast, the other agents target IL-17A or the IL-17 receptor rather than IL-12/23, so they do not belong to the IL-12/23 inhibitor class.