MoonLake Immunotherapeutics Gains FDA Fast Track Designation for Sonelokimab in PPP

MoonLake Immunotherapeutics (NASDAQ: MLTX) jumped about 6.5% in premarket trading after the FDA granted Fast Track designation for the company’s sonelokimab (SLK) program in moderate-to-severe palmoplantar pustulosis (PPP), a chronic inflammatory skin disease with significant unmet need.

Key takeaways:

• FDA Fast Track for sonelokimab in PPP is a meaningful regulatory catalyst that can streamline development and accelerate review timelines.
• The designation follows positive Phase 2 LEDA trial results and supports MoonLake’s broader late-stage inflammatory disease strategy.
• MoonLake is targeting a BLA submission in hidradenitis suppurativa (HS) in the second half of 2026, and Fast Track status can increase FDA engagement along the way.
• Investors now have a tighter near-term catalyst calendar, including a February 23, 2026 Investor Day and multiple data readouts across 2026.

Fast Track designation is intended for therapies addressing serious conditions and unmet medical needs, and it typically comes with more frequent FDA interactions, the possibility of Accelerated Approval and Priority Review (if criteria are met), and the ability to submit sections of a Biologics License Application (BLA) on a rolling basis. For MoonLake, those features can translate into better regulatory visibility and potential time savings as clinical plans mature.

The decision builds on the company’s recent FDA guidance around its clinical evidence strategy for a planned BLA for sonelokimab in HS in 2H 2026. While Fast Track does not guarantee approval, it can improve the efficiency of the path forward by tightening feedback loops and clarifying requirements earlier in the process.

Management framed the move as both a company milestone and a patient-centric signal around disease burden, pointing to the unmet need in PPP and highlighting sonelokimab’s potential to address it. MoonLake remains a clinical-stage biotech focused on inflammatory diseases, positioning sonelokimab as a key asset across multiple indications.

Looking ahead, MoonLake has an Investor Day webcast scheduled for February 23, 2026, where it plans to share the Phase 2 S-OLARIS readout in axial spondyloarthritis (axSpA), discuss FDA feedback in HS, and lay out 2026 catalysts. Upcoming milestones also include the primary endpoint readout for Phase 2 S-OLARIS in February 2026, 52-week data from the VELA trials in HS in Q2 2026, and primary endpoint readouts for Phase 3 programs in psoriatic arthritis and adolescent HS in mid-2026.