NEW YORK, April 01, 2026 (GLOBE NEWSWIRE) — Gainey McKenna & Egleston announces that a securities class action lawsuit has been filed in the United States District Court for the Southern District of California on behalf of all persons or entities who purchased or otherwise acquired Gossamer Bio, Inc. (“Gossamer” or the “Company”) (NASDAQ: GOSS) securities between June 16, 2025, and February 20, 2026, inclusive (the “Class Period”).
The Complaint alleges that Defendants provided investors with material information concerning Gossamer’s Phase 3 PROSERA study evaluating seralutinib for the treatment of pulmonary arterial hypertension (PAH). The Complaint alleges that Defendants’ statements included, among other things, confidence in PROSERA’s trial design.
The Complaint alleges that Defendants provided these overwhelmingly positive statements to investors while, at the same time, disseminating false and misleading statements and/or concealing material adverse facts concerning the study design for the Company’s Phase 3 PROSERA study, particularly, controlling for the placebo response at the Latin American testing sites. The Complaint alleges that this caused Plaintiff and other shareholders to purchase Gossamer’s securities at artificially inflated prices.
The Complaint states that the truth emerged on February 23, 2026 when Gossamer published a press release and hosted a Special Call announcing topline results for its Phase 3 PROSERA study, which failed to meet the primary endpoint of improved six-minute walk distance (6MWD) at Week 24, with a +13.3 meter placebo-adjusted gain (p-0.0320) failing to meet the required 0.025 alpha threshold.
The Complaint states that as a result, investors and analysts reacted immediately to Gossamer’s revelation. The Complaint alleges that the price of Gossamer’s common stock declined from a closing market price of $2.13 per share on February 20, 2026 to $0.42 per share on February 23, 2025, a decline of over 80% in the span of just a single day.
Investors who purchased or otherwise acquired shares of Gossamer should contact the Firm prior to the June 1, 2026 lead plaintiff motion deadline. A lead plaintiff is a representative party acting on behalf of other class members in directing the litigation. If you wish to discuss your rights or interests regarding this class action, please contact Thomas J. McKenna, Esq. or Gregory M. Egleston, Esq. of Gainey McKenna & Egleston at (212) 983-1300, or via e-mail at [email protected] or [email protected].
Please visit our website at http://www.gme-law.com for more information about the firm.
