Many people with psoriatic arthritis do not respond to their initial treatment, and it remains difficult to predict which therapy will work best for a given patient. This project analyzed blood samples to identify immune cell patterns linked to poor response to three commonly used classes of drugs. Certain patterns were more common in patients who did not improve, suggesting these cells may play a role in disease pathogenesis. Improved understanding of these patterns may guide treatment decisions in the future, leading to more personalized and effective care for individuals with psoriatic arthritis.