Experimental Nanobody Showcases Promising Results in Treating Psoriatic Arthritis

A groundbreaking early-stage clinical trial has demonstrated encouraging outcomes for a new treatment targeting psoriatic arthritis, a chronic autoimmune condition affecting joints and skin. The trial involved over 200 patients worldwide and tested a novel nanobody medication called sonelokimab. This drug specifically inhibits two key inflammatory proteins, IL-17A and IL-17F, which are pivotal in the disease process.

Results indicated that patients receiving sonelokimab experienced significant improvements in joint pain, swelling, and skin symptoms compared to those given a placebo. Over half of the participants achieved notable relief in joint symptoms within 24 weeks, with many nearly clearing their skin symptoms. Furthermore, up to 60% of patients reached the goal of minimal disease activity, a key marker of effective treatment. The drug was generally well tolerated, with only mild side effects reported.

Psoriatic arthritis (PsA) is a debilitating condition that can severely impact daily life by causing stiffness, swelling, and pain in joints, tendons, and skin. It affects over a million people in Europe alone, many of whom do not respond adequately to existing therapies.

Sonelokimab is an innovative nanobody developed by MoonLake Immunotherapeutics. Given its small size—about three to four times smaller than traditional antibodies—it may reach inflamed tissues more efficiently. It works by blocking IL-17A and IL-17F, two proteins known to drive inflammation.

Professor Iain McInnes of the University of Glasgow, who led the trial, expressed optimism about the findings and highlighted the next steps will involve larger trials across Europe and America to further evaluate the drug’s effectiveness.

This promising research, published in Nature Medicine (2025), offers hope for more effective treatments for psoriatic arthritis, aiming to improve quality of life for those affected.