MoonLake Announces Positive Topline Results from its Phase 2 Clinical Trial of Sonelokimab in Axial Spondyloarthritis and Reports 2025 Financial Results

• In the Phase 2 S-OLARIS clinical trial in axial spondyloarthritis (axSpA), sonelokimab (SLK) demonstrated clinically meaningful benefit with 80+% of patients achieving ASAS40 by Week 12
• Consistently, other clinical and imaging scores also showed improvements of 80+% by week 12 for patients treated with SLK, including ASDAS-CRP and SPARCC MRI
• axSpA is a disease driven by inflammation leading to irreversible ossification (via osteoblast activity) and ultimately to irreversible restriction of mobility – objective PET/MRI imaging data further showed a significant reduction in inflammation and osteoblast activity deep in affected joints, already by week 12, suggesting potential for disease modification in axSpA for SLK
• As a biomarker-controlled trial, S-OLARIS data showed SLK reduced the levels of key inflammatory mediators in axSpA, in peripheral blood and biopsy samples from patients – the safety profile of SLK was similar to other trials and no new signals were detected
• MoonLake ended the fourth quarter with $394 million in cash, cash equivalents and short-term marketable debt securities which, together with funds from its latest equity raise (gross proceeds of $75 million), are expected to provide a cash runway into the second half of 2027
• The Company also announced the amendment of its debt facility with Hercules Capital, with a concurrent drawdown of $25 million, and up to $400 million in non-dilutive funds remaining available to support future funding needs
• An Investor Day webcast has been confirmed for February 23, 2026, 8.00 – 9.30 am EST (2:00 – 3.30pm CET), including an open Q&A session

ZUG, Switzerland, February 22, 2026 – MoonLake Immunotherapeutics (NASDAQ:MLTX) (“MoonLake” or the “Company”), a clinical-stage biotechnology company focused on creating next-level therapies for inflammatory diseases, today announces topline results from the S-OLARIS Phase 2 trial of SLK in patients with radiographic and non-radiographic axSpA and announces its financial results for the fourth quarter and year ended December 31, 2025. An Investor Day webcast has been confirmed for February 23, 2026, 8.00 – 9.30 am EST (2:00 – 3.30pm CET), including an open Q&A session.

Topline Phase 2 S-OLARIS clinical trial results of SLK in axSpAIn the Phase 2 S-OLARIS trial in axSpA, SLK demonstrated clinically meaningful and statistically significant benefit. 81% of patients treated with SLK (n=26, mNRI), achieved an Assessment of Spondyloarthritis International Society 40 (ASAS40) response at Week 12. ASAS40 measures an improvement of at least 40% and an absolute improvement of ≥2 units on a 0-10 numerical rating scale from baseline in at least three of the four key domains (Patient Global Assessment of disease activity, total back pain, physical function, inflammation), with no worsening in the remaining domain and has been the primary endpoint for the latest approved therapies. More than 80% of patients also achieved a ‘clinically important improvement’ as per ASDAS-CRP score by Week 12 (mNRI). The clinical improvement, in patients treated with SLK, was confirmed by SPARCC MRI scores in the sacroiliac joint (SIJ), measuring inflammation and injury inside the bone, at week 12. This suggests rapid onset of action for SLK and IL-17A and F inhibitory activity in deep, difficult-to-access tissues. Importantly, PET imaging with an 18F-NaF tracer collected as part of the clinical trial showed significant reduction of inflammation and osteoblast activity in sacroiliac joints affected by axSpA, a key driver of irreversible ossification in the disease. Objective peripheral blood and tissue biomarker analyses conducted to control for the effect of SLK, showed rapid and sustained effects of the treatment with SLK in inhibiting key immune pathways known to drive inflammation and ossification in affected patients. The safety profile of SLK in the S-OLARIS trial was consistent with previous trials with no new safety signals detected.

Data from this clinical trial further strengthens the potential of SLK in treating a wide array of inflammatory diseases and represents the fifth indication with positive data, in Phase 2 and Phase 3 clinical trials, for the IL-17A and F Nanobody®.

Prof. Kristian Reich, Founder and Chief Scientific Officer at MoonLake Immunotherapeutics, said: “The data from our S-OLARIS trial marks a critical step in providing an effective treatment for patients with this devastating disease. The complementary data from clinical outcomes, MRI and PET imaging as well as peripheral blood and tissue biomarkers confirm our hypothesis of SLKs ability to access deeper tissue, which is essential to optimally control this chronic rheumatological condition and prevent irreversible mobility restriction. In our view, the impact of SLK on clinical parameters and key disease pathways observed in S-OLARIS already within the first 12 weeks of treatment highlight the potential of the drug to elevate clinical outcomes and to achieve disease modification in axSpA. With millions of patients affected by this devastating condition and limited impact of current therapies in improving relevant disease mechanisms, SLK has the potential to change the treatment paradigm in axSpA.”

Prof. Xenofon Baraliakos, Head of Rheumatology at the Rheumazentrum Ruhrgebiet Herne & President of the European Alliance of Associations for Rheumatology (EULAR) said:“Completing the S-OLARIS trial has been a remarkable milestone for the axSpA and broader Rheumatology community. The combination of clinical, imaging, and biomarker data presents one of the clearest demonstrations to date of how targeting IL-17A and IL-17F with a Nanobody® can meaningfully reduce inflammation in the axial structures. The consistency and speed of response we observed in patients underline the significant potential of sonelokimab to address the unmet needs in this burdensome disease. It has been an honour for our team to contribute to advancing a therapy that could profoundly impact patient lives.”

Financial results for the fourth quarter and year ended December 31, 2025As of December 31, 2025, MoonLake held cash, cash equivalents and short-term marketable debt securities of $394.0 million. Research and development expenses for the quarter ended December 31, 2025, were $56.0 million, compared to $60.6 million in the previous quarter. General and administrative expenses for the quarter ended December 31, 2025 were $9.2 million, compared to the $10.8 million incurred in the previous quarter. The Company expects its cash, cash equivalents and short-term marketable debt securities to be sufficient to fund its operating expenses and capital expenditure requirements into the second half of 2027. In addition, the Company announced the amendment of its debt facility with Hercules Capital, with a concurrent drawdown of $25 million, and up to $400 million in non-dilutive funds remaining available to support future funding needs. The Company expects to file its full annual report on Form 10-K with the U.S. Securities and Exchange Commission on February 25, 2026.

Investor Day, February 23, 2026The Company will hold an Investor Day for investors and analysts on February 23, 2026. The webcast will start at 8.00 – 9.30 am EST (2:00 – 3.30pm CET), including an open Q&A session. A recording will be made available post event. Webcast Access: https://edge.media-server.com/mmc/p/ke4wbinp

In this session, MoonLake's CEO, Jorge Santos da Silva, CSO, Kristian Reich, and CFO, Matthias Bodenstedt, will present the axSpA S-OLARIS data. In addition, the team will discuss the outcomes of the recent Type B FDA Meeting for hidradenitis suppurativa (HS) and next steps regarding label strategy and BLA submission. An interim analysis of the continued response to SLK beyond week 16 from the HS VELA Phase 3 clinical trials in adult patients with HS will also be shared, as will interim data from the VELA‑TEEN clinical trial in adolescent HS. Finally, management will share an update on its financial position and outline key 2026 catalysts, including upcoming data releases from the Phase 3 IZAR trials in Psoriatic Arthritis (PsA), the market opportunity and planned Phase 3 program in palmo-plantar pustulosis (PPP), among other expected milestones.

Important upcoming anticipated milestones for MoonLake:  

• Q2 2026: 52-week data of the VELA-1 and VELA-2 trials in HS
• Mid 2026: Primary endpoint readout of the Phase 3 IZAR-1 trial in PsA
• Mid 2026: Primary endpoint readout of Phase 3 VELA-TEEN trial in adolescent HS
• H2 2026: Submission of a BLA for HS
• H2 2026: Primary endpoint readout of the Phase 3 IZAR-2 trial in PsA

-Ends-

MoonLake ImmunotherapeuticsMoonLake Immunotherapeutics is a clinical-stage biopharmaceutical company unlocking the potential of sonelokimab, a novel investigational Nanobody® for the treatment of inflammatory disease, to revolutionize outcomes for patients. Sonelokimab inhibits IL-17A and IL-17F by inhibiting the IL-17A/A, IL-17A/F, and IL-17F/F dimers that drive inflammation. The Company’s focus is on inflammatory diseases with a major unmet need, including hidradenitis suppurativa, psoriatic arthritis, axial spondyloarthritis and palmoplantar pustulosis – conditions affecting millions of people worldwide with a large need for improved treatment options. MoonLake was founded in 2021 and is headquartered in Zug, Switzerland. Further information is available at www.moonlaketx.com.

About Nanobodies®Nanobodies® represent a new generation of antibody-derived targeted therapies. They consist of one or more domains based on the small antigen-binding variable regions of heavy-chain-only antibodies (VHH). Nanobodies® have a number of potential advantages over traditional antibodies, including their small size, enhanced tissue penetration, resistance to temperature changes, ease of manufacturing, and their ability to be designed into multivalent therapeutic molecules with bespoke target combinations.

The terms Nanobody® and Nanobodies® are trademarks of Ablynx, a Sanofi company.

About SonelokimabSonelokimab (M1095) is an investigational ~40 kDa humanized Nanobody® consisting of three VHHs covalently linked by flexible glycine-serine spacers. With two domains, sonelokimab selectively binds with high affinity to IL-17A and IL-17F, thereby inhibiting the IL-17A/A, IL-17A/F, and IL-17F/F dimers. A third central domain binds to human albumin, facilitating further enrichment of sonelokimab at sites of inflammatory edema.

Sonelokimab is being assessed in two lead indications, hidradenitis suppurativa (HS) and psoriatic arthritis (PsA), and the Company is pursuing other indications in dermatology and rheumatology, including adolescent HS, palmoplantar pustulosis (PPP) and axial spondyloarthritis (axSpA).

For adults with HS, sonelokimab is being assessed in two identical Phase 3 trials, the VELA-1 and VELA-2 trials, using the higher clinical response level of HS Clinical Response (HiSCR) 75 as the primary endpoint, which defines a response as an at least 75% reduction in abscess and inflammatory nodule count, with no increase from baseline in abscess or draining tunnel count. In September 2025, the primary endpoint data from the VELA-1 and VELA-2 clinical trials were announced. In the combined VELA program, patients treated with SLK experienced a clinically meaningful and statistically significant improvement across all primary and key secondary endpoints using both pre-specified strategies (p