MoonLake Extends Sonelokimab Data in Psoriatic Arthritis: What Investors Should Watch

Moonlake Immunotherapeutics (MLTX) announced an update on their ongoing clinical study.

Study Overview

MoonLake Immunotherapeutics (MLTX) is running a long-term Phase 3 study called “A Study to Evaluate the Long-term Safety, Tolerability, and Efficacy of Subcutaneous Sonelokimab in Participants With Psoriatic Arthritis.” The trial follows patients with psoriatic arthritis who finished earlier MoonLake studies and tracks how well sonelokimab works and how safe it remains with continued use. This update matters for investors because long-term data are often key for regulatory approval, label strength, and eventual market uptake in a crowded inflammatory disease space.

Intervention/Treatment

The study tests sonelokimab, an injected drug given under the skin. All participants receive sonelokimab every four weeks. The goal is to control joint and skin symptoms of psoriatic arthritis over the long run while confirming that the safety and side‑effect profile stays acceptable for chronic use.

Study Design

This is an interventional Phase 3 trial with a single treatment group. There is no random assignment and no placebo or active comparator; everyone gets sonelokimab. The study is open-label, which means both doctors and patients know they are receiving the drug. The main purpose is treatment, not prevention or diagnosis, focusing on how patients do over time in real-world‑like conditions after earlier controlled trials.

Study Timeline

The study was first submitted on October 20, 2025, marking the formal start of regulatory tracking and disclosure. It is currently listed as “enrolling by invitation,” meaning only patients who completed the prior Phase 3 parent trials can join. The latest update was filed on December 18, 2025, showing that MoonLake is actively maintaining the record and that the trial is progressing. Primary and final completion dates have not yet been posted, signaling that key readouts remain ahead and will likely line up with later regulatory and commercial milestones.

Market Implications

For investors, this update underscores MoonLake’s push to build a robust, long-term data set for sonelokimab in psoriatic arthritis, a major market currently dominated by biologics from AbbVie, Amgen, Novartis, and others. Positive long-term safety and durability of effect could support premium pricing, strong positioning in treatment guidelines, and broader physician adoption, which in turn would be supportive for MLTX’s valuation. However, the single-arm, open-label design means the trial is better suited to confirm long-term safety and persistence rather than to prove superiority over competing drugs. Investor sentiment may improve as the company demonstrates commitment to follow-up data, but the stock’s longer-term move will hinge on how these results compare with established TNF, IL-17, and IL-23 inhibitors when disclosed.

The study is ongoing and has been recently updated, with more detailed information available on the ClinicalTrials.gov portal under the listed identifier.

To learn more about MLTX’s potential, visit the Moonlake Immunotherapeutics drug pipeline page.