ZUG, Switzerland, August 10, 2026

MoonLake Immunotherapeutics announced positive topline results from its Phase 3 IZAR-1 trial evaluating investigational sonelokimab in biologic-naïve adults with active psoriatic arthritis (PsA). The trial met all clinical endpoints at Week 16 for the 60 mg sonelokimab with induction regimen, demonstrating broad improvements across musculoskeletal symptoms, skin manifestations, physical function and patient-reported outcomes. The primary endpoint, ACR50 response, was achieved by 42.1% of patients, while key secondary endpoints included 66.5% ACR20, 41.2% Minimal Disease Activity (MDA) and 61% PASI90 among patients with concomitant psoriasis. Patients also experienced meaningful improvements in physical function and quality of life, with a HAQ-DI change of -0.427 and an improvement of 6.54 points in SF-36 Physical Component Summary (PCS). The blinded safety analysis remained consistent with previous clinical studies, with no new safety signals identified.

IZAR-1 Demonstrates Broad Clinical Efficacy Across PsA

The IZAR-1 Phase 3 trial is one of two registrational studies within MoonLake’s global IZAR program, with IZAR-1 enrolling biologic-naïve patients and IZAR-2 evaluating patients who are refractory to TNF inhibitors. The Week 16 findings indicate that sonelokimab may address the multiple disease domains associated with psoriatic arthritis, rather than focusing on a single manifestation. The 42.1% ACR50 response represents the primary clinical outcome disclosed for the 60 mg induction group, while the 66.5% ACR20 response further demonstrated improvement in joint-related symptoms. Additionally, 41.2% of patients achieved MDA, indicating substantial disease control across multiple clinical measures. Among patients with skin involvement, 61% achieved PASI90, highlighting sonelokimab’s potential activity against both joint and skin manifestations. The company stated that comparative analyses against placebo remain blinded in accordance with the study’s unblinding protocol.

Sonelokimab Advances Toward a Multi-Billion-Dollar PsA Market

Sonelokimab is an investigational IL-17A/F-targeting Nanobody designed to inhibit IL-17A/A, IL-17A/F and IL-17F/F inflammatory dimers. The positive IZAR-1 results strengthen MoonLake’s strategy of developing the therapy across several inflammatory diseases with significant unmet medical needs. Psoriatic arthritis is a complex and heterogeneous inflammatory condition in which patients can experience joint inflammation, psoriasis, impaired physical function and reduced quality of life. MoonLake highlighted that the simultaneous improvements observed across these domains could support sonelokimab’s potential positioning as a broad treatment option. The company also reported that IZAR-1 will remain blinded through Week 52, allowing assessment of longer-term efficacy and safety, with a full readout expected in the first half of 2027. Meanwhile, the IZAR-2 trial is expected to complete enrollment in Q3 2026, providing additional clinical evidence in TNF-refractory PsA patients

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MoonLake Maintains Funding Through Mid-2028

Alongside the clinical update, MoonLake Immunotherapeutics reported its second-quarter 2026 financial results, ending June 30 with $537.0 million in cash, cash equivalents and short-term marketable debt securities. The company expects its existing capital to fund operating expenses and capital requirements through mid-2028, while its debt facility with Hercules Capital provides access to up to $400 million in additional non-dilutive funding. MoonLake reported $50.2 million in research and development expenses for the second quarter, compared with $54.5 million in the previous quarter, while general and administrative expenses were $11.4 million. The company expects several development milestones ahead, including a planned BLA submission for sonelokimab in hidradenitis suppurativa by the end of September 2026, initiation of palmoplantar pustulosis enrollment in the second half of 2026 and results from the P-OLARIS trial in axial spondyloarthritis around the end of 2026 or early 2027. Together, the positive Phase 3 PsA results, expanding clinical pipeline and strong cash position position MoonLake for a potentially important next phase of development for sonelokimab.

Source: MoonLake Immunotherapeutics, press release