MoonLake drug hits key goals in psoriatic arthritis trial

MoonLake Immunotherapeutics said its psoriatic arthritis drug met key goals in a late-stage trial, moving sonelokimab closer to a possible filing while putting it into one of the most crowded corners of the autoimmune market. Psoriatic arthritis is a chronic inflammatory disease that can damage joints, limit mobility and often travels with psoriasis, so the commercial stakes are tied to whether a new drug can deliver strong, durable control for patients who may need treatment for years.

In biotech, meeting key goals in a phase 3 study usually means the therapy delivered enough efficacy and safety to justify the expensive final steps before approval. For MoonLake, that does not settle the competitive question. The company still has to show how deep the response was, how long it lasted, how clean the safety profile looked and whether sonelokimab can separate itself from established biologics and targeted drugs that already compete for the same patients, especially on speed of action, dosing convenience and durability.

Sonelokimab is MoonLake’s lead candidate, a tri-specific Nanobody that targets IL-17A and IL-17F. In June 2024, MoonLake said it received positive regulatory feedback from both the U.S. Food and Drug Administration and the European Medicines Agency on the path for its phase 3 psoriatic arthritis program. The company’s studies include IZAR-1, NCT06641076, and IZAR-2, NCT06641089, which is designed for patients with active psoriatic arthritis who had an inadequate response or intolerance to anti-TNF therapy. An EU trial listing says the confirmatory phase III program is assessing long-term safety and tolerability across multiple European countries, including France, Germany, Spain, Poland and Hungary.

The late-stage result builds on MoonLake’s earlier phase 2 ARGO trial, which the company said met its primary and key secondary endpoints. MoonLake also said significantly more patients given sonelokimab 120 mg or 60 mg reached ACR50 responses, a benchmark that reflects a 50% improvement in arthritis signs and symptoms. The same drug is also being advanced in hidradenitis suppurativa, underscoring why investors see psoriatic arthritis as more than a single readout: it is part of a broader bet on whether MoonLake can carve out a place in immune-mediated disease against much larger drugmakers.