MoonLake's Sonelokimab Nanobody Achieves Phase 3 Success in PsA and Prepares for Late September HS BLA Submission
MoonLake Immunotherapeutics (Nasdaq: MLTX) is rapidly advancing its lead investigational drug candidate, sonelokimab—a first-in-class, trivalent, IL-17A and IL-17F-inhibiting Nanobody (licensed from Merck KGaA in 2021)—across multiple inflammatory and autoimmune indications.
Positive Phase 3 IZAR-1 Results in Psoriatic Arthritis (PsA)
On August 10, 2026, MoonLake announced positive topline Week 16 results from its Phase 3 IZAR-1 trial evaluating sonelokimab in biologic-naïve adults with active psoriatic arthritis.
- Efficacy: The trial successfully met its primary endpoint, demonstrating a statistically significant and clinically meaningful improvement in signs and symptoms of PsA compared to placebo.
- Secondary Endpoints: Sonelokimab also met all key secondary endpoints, including complete skin clearance, joint symptom resolution, and physical function improvements.
- Modality Advantage: As a Nanobody, sonelokimab's smaller structural size (~40 kDa compared to ~150 kDa for traditional monoclonal antibodies) is designed to enhance tissue penetration, particularly in deep inflammatory skin and joint tissues.
Upcoming Late September BLA Submission in Hidradenitis Suppurativa (HS)
While the PsA results represent a major pipeline expansion, MoonLake's near-term regulatory focus remains centered on hidradenitis suppurativa (HS)—a chronic, painful inflammatory skin disease with highly limited treatment options.
- Following a productive Type B end-of-Phase 2 meeting with the FDA in April 2026, MoonLake is finalized to submit its formal Biologics License Application (BLA) for sonelokimab in adult and adolescent patients with moderate-to-severe HS by the end of September 2026.
- Anticipated Timeline: FDA acceptance of the BLA and a potential Priority Review decision are expected by the end of November 2026.