MoonLake Immunotherapeutics (MLTX) Faces Securities Class Action After Company Reported Disastrous Phase 3 Trial Data For Sole Drug Candidate

Core Viewpoint - MoonLake Immunotherapeutics faces a securities class action lawsuit following the announcement of disappointing Phase 3 trial results for its product candidate sonelokimab (SLK), leading to a significant drop in share price by approximately 90% [1][2][6]. Company Overview - MoonLake Immunotherapeutics is a clinical-stage biotechnology company focused on treating skin inflammatory diseases driven by cytokines IL-17A and IL-17F [3]. Trial Results and Market Reaction - The Phase 3 trials for SLK revealed that only one of the two trials achieved statistical significance, with results showing substantially lower efficacy compared to the competitor's FDA-approved product, BIMZELX [6]. - Following the announcement on September 28, 2025, MoonLake's share price plummeted by $55.75, or about 90%, on September 29, 2025 [2][6]. Allegations of Misleading Information - The lawsuit claims that MoonLake misled investors regarding SLK's trial design and efficacy, asserting that the company made false statements about the advantages of SLK's Nanobody structure over traditional monoclonal antibodies [5]. - Specific allegations include misleading claims about SLK's potential clinical benefits and the distinction between Nanobodies and monoclonal antibodies [5]. Legal Proceedings - The class action lawsuit is focused on the propriety of MoonLake's statements about SLK's trial design and data, with a class period defined from March 10, 2024, to September 29, 2025 [3]. - The lead plaintiff deadline for the lawsuit is set for December 15, 2025 [3].