MoonLake Immunotherapeutics’ sonelokimab has shown benefit in patients with psoriatic arthritis (PsA), with a Phase III trial meeting its primary endpoint.
In the IZAR-1 trial (NCT06641076), which has enrolled biologic-naïve adults with active PsA, the 60mg sonelokimab arm met its primary endpoint at week 16, with 42.1% of patients achieving an American College of Rheumatology 50 (ACR50) response.
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Key secondary clinical endpoints were also met, with 66.5% of patients achieving an ACR20 response, 41.2% achieving Minimal Disease Activity (MDA), and 61% achieving Psoriasis Area and Severity Index 90 (PASI90) response.
Changes were also noted from baseline in the Health Assessment Questionnaire Disability Index (HAQ-DI) and SF-36 Physical Component Summary (PCS) score. 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.
Patients from IZAR-1 will continue to receive treatment or placebo for 52 weeks to evaluate the durability of sonelokimab, with this data expected in H1 2027.
Sonelokimab is also being investigated in PsA in the IZAR-2 (NCT06641089) trial. Unlike IZAR-1, which was only placebo-controlled, IZAR-2 also included a standard of care (SoC) arm. IZAR-2 is investigating sonelokimab compared to AbbVie’s Skyrizi (risankizumab) in patients with active PsA and inadequate response to anti-TNFa, with enrolment expected to complete in Q3 2026.
Dr Jorge Santos da Silva, founder and CEO of MoonLake, said: “The positive topline results from IZAR-1 represent an important milestone for MoonLake and, more importantly, for patients living with psoriatic arthritis. We are particularly encouraged by the strong efficacy observed across multiple clinically relevant endpoints simultaneously, which has been our focus. These data are also encouraging as they are consistent with what was previously observed in other IL-17A/F programmes.”
MoonLake said the Phase III data supports sonelokimab as a therapy to not only address single symptoms of PsA, but also provide meaningful improvements across musculoskeletal symptoms, skin disease, patient quality of life and physical function.
Investors are seemingly not as convinced, however, with MoonLake’s stock dropping 5% on 10 August, from a 7 August close of $18.26 to a 10 August close of $17.33. As of market open on 11 August, the company’s stock price has continued to drop. MoonLake is listed on the Nasdaq exchange with a market cap of $1.41bn.
Previously speaking to Clinical Trials Arena, Dr Christopher Ritchlin, professor of medicine and chief of allergy, immunology and rheumatology at the University of Rochester Medical Center, said that sonelokimab would likely have a hard time competing with UCB’s Bimzelx (bimekizumab) in PsA unless it was able to differentiate itself in terms of efficacy or cost.
MoonLake is also testing the drug’s potential in hidradenitis suppurativa (HS) through the VELA-1 (NCT06411899), VELA-2 (NCT06411379) and VELA-TEEN (NCT06768671) trials. In the Swiss pharma’s VELA-1 and -2 trials, 62% of patients treated with sonelokimab achieved HS clinical response 75 (HiSCR75) at week 40, while 32% achieved HiSCR100.
Sonelokimab also prompted inflammatory remission in 25% of patients who received the drug, which MoonLake defined as a complete clearance of abscesses, nodules, and draining tunnels.
Back in March when the data was released, MoonLake confirmed it would file for sonelokimab’s approval in HS in the second half of 2026, which could see the therapy join a market which GlobalData estimates will be worth $7.8bn by 2034.
GlobalData is the parent company of Clinical Trials Arena.
GlobalData predicts the PsA market across the seven major markets (7MM: US, France, Germany, Italy, Spain, UK, and Japan) will be worth $13.5bn in 2033, up from $9.5bn in 2023.
