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

SAN FRANCISCO, Oct. 16, 2025 /PRNewswire/ -- A securities class action, styled Bridgewood v. MoonLake Immunotherapeutics, et al., No. 1:25-cv-08500 (S.D.N.Y), has been filed after MoonLake (NASDAQ: MLTX) announced disastrous Phase 3 trial results for its only product candidate (sonelokimab, or "SLK"), its highly anticipated treatment for patients with skin disease (hidradenitis suppurativa or "HS").

On this announcement, MoonLake investors saw the price of their shares crater $55.75, or about 90%, on September 29, 2025.

The development and severe market reaction has prompted national shareholders rights firm Hagens Berman to investigate claims that, prior to September 28, 2025, MoonLake misled investors about SLK's trial design and efficacy data.

The firm urges investors in MoonLake who suffered significant losses to submit your losses now. The firm also encourages persons with knowledge who may be able to assist in the investigation to contact its attorneys.

Class Period: Mar. 10, 2024 – Sep. 29, 2025
Lead Plaintiff Deadline: Dec. 15, 2025
Visit:www.hbsslaw.com/investor-fraud/mltx
Contact the Firm Now: [email protected]
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MoonLake Immunotherapeutics (MLTX) Securities Class Action:

The litigation is focused on the propriety of MoonLake's statements about the trial design and data for SLK. The clinical stage biotechnology company is focused on skin inflammatory diseases driven by a cytokines known as IL-17A and IL-17F.

Central to SLK's commercial prospects was its ability to demonstrate efficacy in HS comparable or superior to a competitor's FDA-approved product ("BIMZELX"), which is used for the same HS indication and targets the same cytokines.

One difference between SLK and BIMZELX is that SLK's Nanobody structure is significantly smaller than BIMZELX's monoclonal antibody format.

Throughout the Class Period, MoonLake repeatedly touted SLK's structural advantages as translating into superior efficacy. The company has said that SLK could achieve benefits "a monoclonal antibody cannot do," that "the molecular advantages of our Nanobody translate into higher clinical responses for patients," and that Nanobodies "offer a more convenient and effective treatment."

MoonLake also assured investors that "we really have a drug here that can become the gold standard and obviously that will facilitate any winning that we do with sonelokimab in HS."

The complaint alleges that these, and other, MoonLake statements were false and misleading statements and that the company withheld crucial information from investors. More specifically, the lawsuit claims that the company misled investors about the distinction between Nanobodies and monoclonal antibodies, including that (1) SLK and BIMZELX share the same molecular targets (IL-17A and IL-17F), (2) SLK's Nanobody structure would not confer a superior clinical benefit over the traditional monoclonal structure of BIMZELX, and (3) SLK's Nanobody structure purported increased tissue penetration would not translate to clinical efficacy.

Investors learned the truth on September 28, 2025 after MoonLake revealed that only one of its two SLK Phase 3 trials achieved statistical significance – and even those results demonstrated substantially lower efficacy than BIMZELX.

On this news, the price of MoonLake shares cratered $55.75 (-90%) on September 29, 2025, with one analyst reportedly writing in a note to investors that the results "'arguably fall[] into the worst case outcome.'"

"We're focused on investors' losses and whether MoonLake may have intentionally misled investors about the SLK's purported advantages over BIMZELX while claiming that SLK could become a 'gold standard,'" said Reed Kathrein, the Hagens Berman partner leading the investigation.

If you invested in MoonLake and have substantial losses, or have knowledge that may assist the firm's investigation, submit your losses now »

If you'd like more information and answers to frequently asked questions about the MoonLake case and our investigation, read more »

Whistleblowers: Persons with non-public information regarding MoonLake should consider their options to help in the investigation or take advantage of the SEC Whistleblower program. Under the new program, whistleblowers who provide original information may receive rewards totaling up to 30 percent of any successful recovery made by the SEC. For more information, call Reed Kathrein at 844-916-0895 or email [email protected].

About Hagens Berman
Hagens Berman is a global plaintiffs' rights complex litigation firm focusing on corporate accountability. The firm is home to a robust practice and represents investors as well as whistleblowers, workers, consumers and others in cases achieving real results for those harmed by corporate negligence and other wrongdoings. Hagens Berman's team has secured more than $2.9 billion in this area of law. More about the firm and its successes can be found at hbsslaw.com. Follow the firm for updates and news at @ClassActionLaw.

SOURCE Hagens Berman Sobol Shapiro LLP