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There is no cost or obligation associated with submitting your information. If you are a shareholder who suffered a loss, please submit your contact information and purchase information to participate in the putative class action.

We also encourage you to contact Lesley F. Portnoy of The Portnoy Law Firm, at 310.692.8883, to discuss your rights free of charge. You can also reach us through the firm’s website at, or by email at

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Joining the case through the Portnoy Law website enables investors to learn about their legal claims and take an active role in recovering their losses.

The Portnoy Law Firm represents investors around the world and specializes in securities class action lawsuits and shareholder rights litigation.

Portnoy Law Firm
Lesley F. Portnoy, Esq.,
Office: 310.692.8883
1800 Century Park East, Suite 600
Los Angeles, CA 90067

ACELYRIN is a clinical biopharmaceutical company with a primary focus on developing and bringing transformative medicines to market. The ACELYRIN class action lawsuit centers on ACELYRIN’s lead product candidate, izokibep, which was undergoing Part B of a Phase 2b/3 clinical trial for the treatment of moderate to severe Hidradenitis Suppurativa (“HS”).

The allegations in the ACELYRIN class action lawsuit revolve around the assertion that the defendants, over the Class Period, either made false and/or misleading statements or failed to disclose critical information, which include:

  1. The claim that izokibep’s effectiveness in treating HS was less significant than what the defendants had led investors to believe.
  2. Consequently, ACELYRIN had overstated the clinical and/or commercial prospects of izokibep.
  3. As a result, ACELYRIN had also exaggerated its business prospects following its initial public offering.

Furthermore, the ACELYRIN class action lawsuit states that on September 11, 2023, ACELYRIN made a disappointing announcement concerning the top-line results from Part B of the Phase 2b/3 trial evaluating izokibep for the treatment of moderate-to-severe HS. Specifically, it was alleged that izokibep failed to demonstrate a statistically significant reduction in abscesses and inflammatory nodules in patients when compared to the placebo. In response to this news, the price of ACELYRIN stock experienced a substantial decline of more than 61% over the course of two trading sessions.