MoonLake Announces FDA Fast Track Designation for Sonelokimab Palmoplantar Pustulosis (PPP) and Provides Details on Upcoming Investor Day

• The Dermatology Division of the U.S. Food and Drug Administration (FDA) has granted Fast Track designation to sonelokimab (SLK) in moderate-to-severe palmoplantar pustulosis (PPP) supported by positive results from the Phase 2 LEDA trial
• The upcoming Phase 3 program will therefore be expected to benefit from earlier and more frequent interactions with the FDA under the Fast Track program, potentially enabling a more efficient development pathway
• This regulatory decision follows the recent clear guidance from the FDA, in which the Company confirmed its clinical evidence strategy for the planned submission of a Biologic License Application (BLA) in H2 2026 for SLK in hidradenitis suppurativa (HS)
• The PPP program will be discussed at the upcoming Investor Day webcast, confirmed for February 23, 2026, 8.00 – 9.30 am EST (2:00 – 3.30pm CET), including an open Q&A session
• The Company will also present the Phase 2 S-OLARIS readout in axial spondyloarthritis (axSpA) as the first in a series of rheumatology readouts expected in 2026, discuss FDA feedback, label strategy and new data for SLK in adult and adolescent hidradenitis suppurativa (HS), provide guidance for the upcoming psoriatic arthritis (PsA) Phase 3 IZAR readouts, and outline key catalysts for MLTX
• The webcast can be accessed at: https://edge.media-server.com/mmc/p/ke4wbinp

ZUG, Switzerland, February 2, 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 that the FDA has granted Fast Track designation for sonelokimab for the treatment of moderate‑to‑severe PPP. MoonLake had submitted a request for Fast Track designation on December 1, 2025. This follows the positive outcome of the Company’s recent FDA interactions in which it confirmed its clinical evidence strategy for the planned submission of a BLA for SLK in HS in H2 2026. The Company also confirmed details for its upcoming Investor Day, which will take place on February 23, 2026, featuring in‑depth clinical and regulatory updates across multiple indications, including newly generated data from the S‑OLARIS program for SLK in axSpA.

Fast Track is an FDA program designed to facilitate the development and expedite the review of drugs to treat serious conditions and fill an unmet medical need. Its purpose is to help important new therapies reach patients earlier. Granting Fast Track designation is generally based on whether a drug has the potential to improve survival, enhance day‑to‑day functioning, or prevent a condition from progressing from a less severe to a more serious stage.

FDA granted Fast Track designation for SLK in PPP, reflecting both the severe burden of this chronic inflammatory condition and the absence of any approved treatments. The Fast Track framework provides opportunities for the development program of sonelokimab in moderate-to-severe PPP to proceed under a streamlined fashion, including the following expected enhancements:

(1) More frequent FDA interactions to discuss the development plan and ensure collection of appropriate data necessary to support drug approval

(2) More frequent written communication from FDA about such things as the design of the proposed clinical trials and use of biomarkers

(3) Potential eligibility for Accelerated Approval and Priority Review, if applicable criteria are met

(4) Rolling Review, which allows completed BLA sections to be submitted for FDA review on a rolling basis

Dr. Jorge Santos da Silva, Founder and Chief Executive Officer at MoonLake Immunotherapeutics, said: “This FDA decision marks an important milestone for MoonLake and for patients living with PPP. It underscores the significant unmet need in this debilitating disease and SLK’s potential to address it. With Fast Track designation, we believe this can support the acceleration of our Phase 3 program through earlier and more frequent FDA engagement, enabling faster addressing of development questions, as we seek to advance sonelokimab toward approval for PPP patients. We look forward to sharing further updates on PPP and across the multiple programs expected to read out through 2026, as well as on the BLA submission for HS, in our upcoming Investor Day”

The Company will hold an Investor Day for investors and analysts on February 23rd, 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

Further to discussing the market opportunity and upcoming Phase 3 program in PPP, MoonLake's management will present the data readout of the axSpA Phase 2 S-OLARIS program. In addition, the team will discuss the outcomes of the recent Type B FDA Meeting for 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), among other expected milestones.

Important upcoming anticipated milestones for MoonLake:  

• Feb 2026: Primary endpoint readout of the Phase 2 S-OLARIS trial in axSpA
• 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

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About 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