MoonLake Immunotherapeutics Delivers Strong Phase 2 Results For Sonelokimab In axSpA & Announces Solid 2025 Financial Performance

MoonLake Immunotherapeutics, a clinical-stage biotechnology company developing next-generation therapies for inflammatory diseases, has released new updates covering both scientific progress and financial performance. The company announced the topline results from its Phase 2 S-OLARIS trial evaluating SLK in patients with radiographic and non-radiographic axial spondyloarthritis (axSpA). It also shared its financial results for the fourth quarter and full year ending December 31, 2025. In addition, an Investor Day webcast has been scheduled for February 23, 2026, from 8:00 to 9:30 am EST (2:00 to 3:30 pm CET), featuring an open Q&A session.

The Phase 2 S-OLARIS trial demonstrated that SLK delivered clinically meaningful and statistically significant results. At Week 12, 81% of patients receiving SLK (n=26, mNRI) achieved an ASAS40 response. This assessment requires a minimum of 40% improvement and at least a 2-unit reduction on a 0–10 scale across three out of four domains: patient global assessment, total back pain, physical function, and inflammation, without worsening in the fourth domain. This endpoint is widely recognized as a key measure used in evaluating newly approved therapies.

More than 80% of patients also achieved a clinically important improvement based on ASDAS-CRP scores by Week 12. Beyond clinical symptom improvement, imaging data reinforced the findings. MRI assessments using SPARCC scoring showed reductions in inflammation and bone involvement in the sacroiliac joint, supporting the conclusion that SLK delivers early therapeutic action. PET imaging with an 18F-NaF tracer further demonstrated a notable reduction in inflammation and osteoblast activity, both of which contribute to irreversible bone formation often seen in axSpA. 

Biomarker tests conducted on blood and tissue samples confirmed rapid and sustained suppression of key immune pathways linked to inflammation and ossification. The safety profile observed was consistent with previous studies, with no new or unexpected safety issues. These results build on MoonLake’s growing body of evidence supporting SLK as a potential treatment for several inflammatory conditions. This marks the fifth disease area in which the IL-17A and IL-17F Nanobody® has delivered positive outcomes in Phase 2 or Phase 3 trials.

Kristian Reich, Founder and Chief Scientific Officer of MoonLake, stated that the S-OLARIS results are an important step forward, indicating that SLK can reach deeper tissues where inflammation and structural changes occur in axSpA. He noted that the improvements seen within 12 weeks highlight SLK’s potential to improve long-term outcomes and possibly modify the course of the disease.

Xenofon Baraliakos, Head of Rheumatology at the Rheumazentrum Ruhrgebiet Herne and President of EULAR, commented that completing the S-OLARIS trial represents a major milestone for the rheumatology field. He emphasized that the alignment between clinical results, imaging data, and biomarker findings provides strong evidence of the benefits of targeting IL-17A and IL-17F and demonstrates how SLK may address unmet needs for axSpA patients.

MoonLake also reported its financial results for the fourth quarter and full year ending December 31, 2025. The company held $394.0 million in cash, cash equivalents, and short-term marketable debt securities as of year-end. Research and development expenses for the fourth quarter were $56.0 million, down from $60.6 million in the previous quarter. General and administrative expenses totaled $9.2 million, compared with $10.8 million in the previous quarter. Based on its current financial position, the company expects to be able to fund operations into the second half of 2027.

MoonLake also amended its debt facility with Hercules Capital and completed a drawdown of $25 million. The company still has access to up to $400 million in non-dilutive funding under this agreement, which may be used to support future operational needs. MoonLake plans to file its annual report on Form 10-K with the U.S. Securities and Exchange Commission on February 25, 2026.