Gossamer Bio's Phase 3 Trial Results Disappoint
Written by Emily J. Thompson, Senior Investment Analyst
Updated: Feb 23 2026
0mins
Source: Benzinga
Gossamer Bio's shares fell sharply, hitting a 52-week low, following disappointing results from its Phase 3 PROSERA trial for seralutinib, which showed significant but insufficient improvement in patient mobility.
The trial revealed that seralutinib led to a median change of +28.2 meters in Six-Minute Walk Distance (6MWD) at Week 24, failing to meet the predefined efficacy threshold. However, in a subgroup of patients with connective tissue disease-associated pulmonary arterial hypertension, the drug achieved a placebo-adjusted gain of +37.0 meters, indicating potential effectiveness. Gossamer plans to meet with the U.S. FDA to discuss future development for seralutinib while pausing enrollment in the SERANATA study to evaluate the impact of these results.
The market reacted negatively, with Gossamer Bio's shares plummeting by 77.12% to $0.59, reflecting investor disappointment and prompting analysts to lower their earnings expectations.
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Analyst Views on GOSS
Wall Street analysts forecast GOSS stock price to rise
4 Analyst Rating
3 Buy
1 Hold
0 Sell
Strong Buy
Current: 0.201
Low
10.00
Averages
12.33
High
15.00
Current: 0.201
Low
10.00
Averages
12.33
High
15.00
About GOSS
Gossamer Bio, Inc. is a late-stage, clinical biopharmaceutical company, which is focused on the development and commercialization of seralutinib for the treatment of pulmonary arterial hypertension and pulmonary hypertension associated with interstitial lung disease (PH-ILD). Seralutinib, also known as GB002, is an investigational inhaled, small-molecule, platelet-derived growth factor receptor (PDGFR), colony-stimulating factor 1 receptor (CSF1R), and c-KIT inhibitor, being evaluated in a Phase III clinical trial for the treatment of PAH. Seralutinib is designed to target the mechanisms that underlie pulmonary hypertension and to be delivered to the site of disease, via dry powder inhaler. Seralutinib is being evaluated in a Phase III clinical trial for the treatment of pulmonary arterial hypertension (PAH). Inhaled seralutinib, which is designed to act on both isoforms of the PDGFR, α and β, as well as the CSF1R and c-KIT pathways.
About the author
Emily J. Thompson
Emily J. Thompson, a Chartered Financial Analyst (CFA) with 12 years in investment research, graduated with honors from the Wharton School. Specializing in industrial and technology stocks, she provides in-depth analysis for Intellectia’s earnings and market brief reports.
Reminder of Gossamer Bio Securities Class Action
- Class Action Notice: Rosen Law Firm reminds investors who purchased Gossamer Bio securities between June 16, 2025, and February 20, 2026, to apply as lead plaintiffs by June 1, 2026, to participate in the class action and potentially receive compensation without any out-of-pocket costs.
- Lawsuit Background: The lawsuit alleges that defendants made overwhelmingly positive statements about Gossamer's Phase 3 PROSERA study while concealing significant adverse facts regarding the study design, resulting in investor losses when the truth emerged.
- Law Firm Credentials: Rosen Law Firm specializes in securities class actions and has recovered over $438 million for investors in 2019 alone, being ranked first in 2017 for the number of securities class action settlements, showcasing its strong reputation in this field.
- Investor Selection Advice: Investors are advised to carefully select qualified counsel with a proven track record, avoiding firms that merely act as intermediaries, to ensure they receive the best legal support and potential compensation in the class action.
See More
Class Action Lawsuit Filed Against Gossamer Bio, Inc.
- Lawsuit Background: Bronstein, Gewirtz & Grossman has filed a class action lawsuit against Gossamer Bio, alleging violations of federal securities laws on behalf of all investors who purchased Gossamer securities between June 16, 2025, and February 20, 2026.
- False Statements Allegation: The complaint claims that Gossamer misled investors by touting positive results from its PROSERA study while concealing significant adverse facts regarding the study's design at Latin American sites, resulting in artificially inflated stock prices that harmed investors.
- Investor Action: Affected investors have until June 1, 2026, to request to be appointed as lead plaintiff, with the law firm operating on a contingency fee basis, ensuring no upfront costs for investors wishing to join the lawsuit.
- Law Firm Credentials: Bronstein, Gewirtz & Grossman is recognized for recovering hundreds of millions for investors in securities fraud class actions, emphasizing its commitment to restoring investor capital and ensuring corporate accountability in the marketplace.
See More
Gossamer Bio Faces Class Action Lawsuit
- Class Action Reminder: The Schall Law Firm alerts investors of a class action lawsuit against Gossamer Bio for violations of §§10(b) and 20(a) of the Securities Exchange Act, concerning securities purchased between June 16, 2025, and February 20, 2026, with a deadline to contact the firm by June 1, 2026, for participation.
- False Statement Allegations: The complaint alleges that Gossamer concealed adverse facts regarding the design of its Phase 3 PROSERA study, particularly concerning controls for placebo response at certain testing sites, rendering its public statements false and materially misleading throughout the class period.
- Investor Losses: As the market learned the truth about Gossamer, investors suffered damages, indicating serious deficiencies in the company's disclosure practices that could impact future stock performance and investor confidence.
- Legal Consultation Opportunity: The Schall Law Firm offers free consultations, encouraging affected shareholders to reach out to discuss their rights, demonstrating the firm's commitment to protecting investor interests while highlighting the potential legal risks facing Gossamer.
See More
Multiple Companies Facing Class Action Lawsuits
- Pinterest Lawsuit Overview: Pinterest, Inc. is facing allegations of false statements during the class period from February 7, 2025, to February 12, 2026, which may lead to significant revenue losses and potential restructuring, with a lead plaintiff deadline of May 29, 2026.
- New Era Energy Allegations: New Era Energy & Digital, Inc. is accused of overstating progress on its Texas data center project and engaging in fraudulent schemes from November 6, 2024, to December 29, 2025, with a lead plaintiff deadline of June 1, 2026.
- Gossamer Bio Lawsuit Details: Gossamer Bio, Inc. faces claims of failing to disclose the failure of its clinical trial from June 16, 2025, to February 20, 2026, misleading investors about the company's prospects, with a lead plaintiff deadline of June 1, 2026.
- Medpace Holdings Lawsuit Information: Medpace Holdings, Inc. is accused of making false statements regarding its financial metrics from April 22, 2025, to February 9, 2026, with a lead plaintiff deadline of June 8, 2026, potentially impacting the company's future financing capabilities.
See More
Class Action Lawsuits Filed Against Gossamer Bio and Others
- Class Action Overview: The Law Offices of Frank R. Cruz remind investors that class action lawsuits have been filed against companies like Gossamer Bio, urging affected shareholders to file lead plaintiff motions by the specified deadlines to protect their legal rights.
- Gossamer Bio Allegations: During the period from June 16, 2025, to February 20, 2026, Gossamer Bio is accused of failing to disclose critical issues in its clinical trials, resulting in its Phase 3 PROSERA study not meeting primary endpoints, which negatively impacted investor confidence.
- New Era Energy Allegations: From November 6, 2024, to December 29, 2025, New Era Energy is alleged to have overstated progress on its Texas Critical Data Centers project and engaged in fraudulent schemes, leading to misleading financial results that affected shareholders.
- Medpace Holdings Allegations: During the period from April 22, 2025, to February 9, 2026, Medpace Holdings is accused of overstating its projected book-to-bill ratio for Q4 2025 and failing to adequately assess the impact of cancellations on its business, misleading investors about its operational health.
See More
Reminder for Gossamer Bio Securities Class Action
- Class Action Notice: Rosen Law Firm reminds investors who purchased Gossamer Bio securities between June 16, 2025, and February 20, 2026, to apply as lead plaintiffs by June 1, 2026, to participate in the class action and seek compensation.
- Fee Arrangement: Investors joining the class action will incur no upfront costs, as the law firm operates on a contingency fee basis, which alleviates financial burdens and encourages more victims to participate.
- Lawsuit Background: The lawsuit alleges that Gossamer Bio provided overly optimistic statements while concealing significant adverse facts regarding the study design of its Phase 3 PROSERA study, resulting in investor losses when the truth emerged.
- Law Firm Credentials: Rosen Law Firm specializes in securities class actions and has achieved the largest securities class action settlement against a Chinese company, demonstrating its expertise and success in the field, which enhances investor confidence in their representation.
See More
Reminder of Gossamer Bio Securities Class Action
- Class Action Notice: Rosen Law Firm reminds investors who purchased Gossamer Bio securities between June 16, 2025, and February 20, 2026, to apply as lead plaintiffs by June 1, 2026, to participate in the class action and potentially receive compensation without any out-of-pocket costs.
- Lawsuit Background: The lawsuit alleges that defendants made overwhelmingly positive statements about Gossamer's Phase 3 PROSERA study while concealing significant adverse facts regarding the study design, resulting in investor losses when the truth emerged.
- Law Firm Credentials: Rosen Law Firm specializes in securities class actions and has recovered over $438 million for investors in 2019 alone, being ranked first in 2017 for the number of securities class action settlements, showcasing its strong reputation in this field.
- Investor Selection Advice: Investors are advised to carefully select qualified counsel with a proven track record, avoiding firms that merely act as intermediaries, to ensure they receive the best legal support and potential compensation in the class action.
See More
Class Action Lawsuit Filed Against Gossamer Bio, Inc.
- Lawsuit Background: Bronstein, Gewirtz & Grossman has filed a class action lawsuit against Gossamer Bio, alleging violations of federal securities laws on behalf of all investors who purchased Gossamer securities between June 16, 2025, and February 20, 2026.
- False Statements Allegation: The complaint claims that Gossamer misled investors by touting positive results from its PROSERA study while concealing significant adverse facts regarding the study's design at Latin American sites, resulting in artificially inflated stock prices that harmed investors.
- Investor Action: Affected investors have until June 1, 2026, to request to be appointed as lead plaintiff, with the law firm operating on a contingency fee basis, ensuring no upfront costs for investors wishing to join the lawsuit.
- Law Firm Credentials: Bronstein, Gewirtz & Grossman is recognized for recovering hundreds of millions for investors in securities fraud class actions, emphasizing its commitment to restoring investor capital and ensuring corporate accountability in the marketplace.
See More
Gossamer Bio Faces Class Action Lawsuit
- Class Action Reminder: The Schall Law Firm alerts investors of a class action lawsuit against Gossamer Bio for violations of §§10(b) and 20(a) of the Securities Exchange Act, concerning securities purchased between June 16, 2025, and February 20, 2026, with a deadline to contact the firm by June 1, 2026, for participation.
- False Statement Allegations: The complaint alleges that Gossamer concealed adverse facts regarding the design of its Phase 3 PROSERA study, particularly concerning controls for placebo response at certain testing sites, rendering its public statements false and materially misleading throughout the class period.
- Investor Losses: As the market learned the truth about Gossamer, investors suffered damages, indicating serious deficiencies in the company's disclosure practices that could impact future stock performance and investor confidence.
- Legal Consultation Opportunity: The Schall Law Firm offers free consultations, encouraging affected shareholders to reach out to discuss their rights, demonstrating the firm's commitment to protecting investor interests while highlighting the potential legal risks facing Gossamer.
See More
Multiple Companies Facing Class Action Lawsuits
- Pinterest Lawsuit Overview: Pinterest, Inc. is facing allegations of false statements during the class period from February 7, 2025, to February 12, 2026, which may lead to significant revenue losses and potential restructuring, with a lead plaintiff deadline of May 29, 2026.
- New Era Energy Allegations: New Era Energy & Digital, Inc. is accused of overstating progress on its Texas data center project and engaging in fraudulent schemes from November 6, 2024, to December 29, 2025, with a lead plaintiff deadline of June 1, 2026.
- Gossamer Bio Lawsuit Details: Gossamer Bio, Inc. faces claims of failing to disclose the failure of its clinical trial from June 16, 2025, to February 20, 2026, misleading investors about the company's prospects, with a lead plaintiff deadline of June 1, 2026.
- Medpace Holdings Lawsuit Information: Medpace Holdings, Inc. is accused of making false statements regarding its financial metrics from April 22, 2025, to February 9, 2026, with a lead plaintiff deadline of June 8, 2026, potentially impacting the company's future financing capabilities.
See More
Class Action Lawsuits Filed Against Gossamer Bio and Others
- Class Action Overview: The Law Offices of Frank R. Cruz remind investors that class action lawsuits have been filed against companies like Gossamer Bio, urging affected shareholders to file lead plaintiff motions by the specified deadlines to protect their legal rights.
- Gossamer Bio Allegations: During the period from June 16, 2025, to February 20, 2026, Gossamer Bio is accused of failing to disclose critical issues in its clinical trials, resulting in its Phase 3 PROSERA study not meeting primary endpoints, which negatively impacted investor confidence.
- New Era Energy Allegations: From November 6, 2024, to December 29, 2025, New Era Energy is alleged to have overstated progress on its Texas Critical Data Centers project and engaged in fraudulent schemes, leading to misleading financial results that affected shareholders.
- Medpace Holdings Allegations: During the period from April 22, 2025, to February 9, 2026, Medpace Holdings is accused of overstating its projected book-to-bill ratio for Q4 2025 and failing to adequately assess the impact of cancellations on its business, misleading investors about its operational health.
See More
Reminder for Gossamer Bio Securities Class Action
- Class Action Notice: Rosen Law Firm reminds investors who purchased Gossamer Bio securities between June 16, 2025, and February 20, 2026, to apply as lead plaintiffs by June 1, 2026, to participate in the class action and seek compensation.
- Fee Arrangement: Investors joining the class action will incur no upfront costs, as the law firm operates on a contingency fee basis, which alleviates financial burdens and encourages more victims to participate.
- Lawsuit Background: The lawsuit alleges that Gossamer Bio provided overly optimistic statements while concealing significant adverse facts regarding the study design of its Phase 3 PROSERA study, resulting in investor losses when the truth emerged.
- Law Firm Credentials: Rosen Law Firm specializes in securities class actions and has achieved the largest securities class action settlement against a Chinese company, demonstrating its expertise and success in the field, which enhances investor confidence in their representation.
See More
