• Phase 3 IZAR-1 trial in bio-naïve patients met all clinical endpoints at Week 16 for 60 mg sonelokimab
  • The primary endpoint of ACR50 was met with a high response of 42.1% for sonelokimab’s 60 mg with induction, and significant responses were observed across key secondary endpoints, including ACR20 (66.5%), MDA (41.2%) and PASI90 (61%), supporting the broad multidomain efficacy profile of sonelokimab in psoriatic arthritis
  • Meaningful and statistically significant improvements were seen across patient-reported outcomes and physical function measures, including HAQ-DI and SF-36 PCS
  • Blinded safety analysis suggests a profile consistent with previous studies and no new safety signals were identified, reinforcing sonelokimab's potential to become a leading treatment option for patients living with psoriatic arthritis, and enabling MoonLake’s entry into another multi-billion dollar indication
  • The IZAR-1 trial remains blinded and will continue until Week 52 with MoonLake expecting the full readout in H1 2027 whereas the IZAR-2 trial (a trial in TNF-refractory patients) is expected to complete enrollment in Q3 2026
  • MoonLake ended the second quarter with $537.0 million in cash, cash equivalents and short-term marketable debt securities and expects to have a cash runway to mid-2028; additionally, up to $400 million in non-dilutive funds remain available through its debt facility with Hercules Capital

ZUG, Switzerland, August 10, 2026 – MoonLake Immunotherapeutics (NASDAQ:MLTX) ("MoonLake" or the "Company"), a clinical-stage biotechnology company focused on creating next-level therapies for inflammatory diseases, today announced positive topline results from the Phase 3 IZAR-1 trial evaluating sonelokimab in biologic-naïve adults with active psoriatic arthritis (PsA) and reported second quarter 2026 financial results.

IZAR-1 Phase 3 trial Week 16 positive topline results

The IZAR Phase 3 program consists of two registrational global randomized, double-blind trials, IZAR-1 and IZAR-2, designed to evaluate the efficacy and safety of sonelokimab in adults with active psoriatic arthritis (PsA). IZAR-1 is being conducted in biologic-naïve adults with active PsA. Following the Week 16 primary endpoint analysis, patients will continue participating in their respective studies through Week 52 to evaluate the durability of efficacy and safety of sonelokimab.

The primary endpoint of IZAR-1 is the percentage of patients achieving an American College of Rheumatology 50 (ACR50) response at Week 16. Key secondary clinical endpoints evaluate the broad multidomain efficacy of sonelokimab across musculoskeletal, skin, patient-reported and physical outcomes and include the percentage of patients achieving an ACR20 response, Minimal Disease Activity (MDA), and Psoriasis Area and Severity Index 90 (PASI90) response, as well as changes from baseline in the Health Assessment Questionnaire Disability Index (HAQ-DI) and SF-36 Physical Component Summary (PCS) score.

The Phase 3 IZAR-1 trial met all clinical endpoints at Week 16 for 60 mg sonelokimab. Consistent with the unblinding protocol defined with the FDA, topline disclosure at Week 16 includes absolute response levels and endpoint outcomes for the sonelokimab 60 mg with induction arm. Comparative analyses versus placebo and detailed treatment arm data remain blinded until completion of the Phase 3 program.

A total of 42.1% of biologic-naïve patients treated with sonelokimab 60 mg with induction achieved an ACR50 response. In addition, sonelokimab demonstrated strong efficacy across multiple disease domains characteristic of PsA. Across key secondary clinical endpoints, 66.5% of patients achieved ACR20, and 41.2% achieved MDA at Week 16. In patients with concomitant skin involvement, 61% achieved PASI90 at Week 16. Patients treated with sonelokimab also demonstrated clinically meaningful improvements in patient-reported and physical outcomes. Mean change from baseline in HAQ-DI was -0.427, while improvements were observed in SF-36 Physical Component Summary (PCS) with a score of 6.54. IZAR-1 does not include a Standard of Care arm as ARGO had provided data in such context for the Bio-Naïve population (adalimumab arm). IZAR-2 will provide data in comparison with a Standard of Care (risankizumab) in TNF-refractory patients.

The blinded safety analysis of IZAR-1 suggests a profile consistent with previous clinical studies and no new safety signals were observed. In addition, the drop-out rate of IZAR-1 until Week 16 is low and in line with other trials in PsA.

These results further support the potential of sonelokimab to address, not just single symptoms of PsA, but rather the diverse manifestations of psoriatic arthritis through meaningful improvements across musculoskeletal symptoms, skin disease, patient quality of life and physical function. After the lead indication of hidradenitis suppurativa (HS) these results set the path for sonelokimab to compete in another multi-billion dollar indication.