Gossamer Bio, Inc.
Case Overview
| Lead Plaintiff Deadline: | Lead Plaintiff Deadline: 06/01/2026 |
| Status: | Status: Investigating |
| Company Name: | Company Name: Gossamer Bio, Inc. |
| Court: | Court: Southern District of California |
| Case Number: | Case Number: 3:26cv02016 |
| Class Period: | Class Period: 06/16/2025 - 02/20/2026 |
| Ticker: | Ticker: GOSS |
| Related Attorneys: | Lead Attorneys: Thomas W. Elrod |
| Related Practices: | Related Practices: Securities |
The law firm of Kirby McInerney LLP announces that a class action lawsuit has been filed on behalf of investors who acquired Gossamer Bio, Inc. (“Gossamer” or the “Company”) (NASDAQ:GOSS) securities during the period of June 16, 2025 through February 20, 2026, inclusive (“the Class Period”).
The lawsuit alleges that the Company provided 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.
On February 23, 2026, 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. Gossamer attributed this miss to patients at Latin American sites performing particularly well on placebo due to enrollment of a heavily-treated lower-risk population. On this news, the price of Gossamer shares declined by $1.71 per share, or approximately 80%, from $2.13 per share on February 20, 2026 to close at $0.42 on February 23, 2026.