MoonLake's sonelokimab hits 67% HiSCR75 at one year in HS

MoonLake Immunotherapeutics has released one-year efficacy and safety data from its Phase 3 VELA programme in moderate-to-severe hidradenitis suppurativa (HS), reporting that 67.2% of patients treated with sonelokimab (SLK) achieved HiSCR75 at Week 52 across the pooled VELA-1 and VELA-2 trials (n=396). A further 33.1% reached HiSCR100, representing complete clearance of abscesses, nodules and draining tunnels, while 26.0% achieved inflammatory remission as defined by IHS4-100.

The results build on primary endpoint data published in September 2025, which showed VELA-1 met statistical significance for HiSCR75 against placebo, while VELA-2 was complicated by higher-than-expected placebo response rates that prevented it from achieving significance on the composite strategy. The Week 52 dataset, presented ahead of MoonLake's Investor Day on 22 June, shows continued improvement across both trials and consistent performance between the two studies.

Clinical profile

Patient-reported outcomes reinforced the primary findings. The HS-specific quality-of-life score (HiSQOL) showed a mean improvement of roughly 15 points from baseline to Week 52 in both VELA-1 and VELA-2, a shift the company characterises as moving the average patient from "severe" to "mild" impairment. In addition, 46.5% of patients experienced a meaningful reduction in worst skin pain of at least three points on the Numerical Rating Scale, and more than 70% of patients in VELA-1 achieved a clinically meaningful improvement on the broader Dermatology Life Quality Index. Approximately 90% of participants rolled over into the two-year open-label extension, which MoonLake cites as evidence of good tolerability and convenience of the once-every-four-weeks subcutaneous dosing schedule.

Interim data from the VELA-TEEN trial, an open-label Phase 3 study in 35 adolescents aged 12 to 17, showed approximately 68% achieving HiSCR75 and roughly 45% reaching HiSCR100 at Week 24, with no new safety signals. MoonLake intends to include the adolescent dataset in its forthcoming regulatory submission.

Regulatory path and competitive context

MoonLake plans to file a Biologics Licence Application (BLA) with the FDA at the end of September 2026, following completion of the pre-BLA process. The company expects PDUFA date allocation by late November 2026 and will request Priority Review, citing the strength of the one-year data and the inclusion of adolescent patients. Priority Review remains contingent on FDA capacity, the company noted. If standard review applies, a US launch is projected in the third or fourth quarter of 2027; Priority Review could accelerate this by approximately one quarter.

The HS treatment landscape has expanded considerably since adalimumab received its initial HS approval in 2015. Secukinumab, an IL-17A inhibitor from Novartis, received FDA approval in HS in late 2023, and bimekizumab, UCB's dual IL-17A and IL-17F inhibitor, secured approval in 2024, establishing the IL-17 pathway as the leading therapeutic axis in the condition. MoonLake positions sonelokimab, a Nanobody that inhibits both IL-17A and IL-17F homodimers as well as the heterodimer, as offering superior response rates compared with both approved agents at equivalent trial timepoints, citing roughly 10 percentage points more responding patients for HiSCR75 versus the comparator IL-17A/F inhibitor. Independent validation of these cross-trial comparisons will be important, as patient populations and trial designs can introduce material differences that make head-to-head interpretation difficult.

The projected HS market, estimated by MoonLake at around $15 billion by 2035, reflects a large and underdiagnosed patient population. With two approved biologics already on the market and further candidates in development, commercial differentiation will depend on label breadth, real-world safety data, and pricing. The adolescent indication and a clean one-year safety dataset give MoonLake a credible basis for pursuing a differentiated label, though the BLA review outcome and the IZAR programme readouts in psoriatic arthritis will shape the longer-term commercial story.