Gossamer Bio Investors Sought to Lead Lawsuit After Seralutinib Trial Failure

Overview

• The Law Offices of Frank R. Cruz invited shareholders with losses to seek the lead plaintiff role in the securities case, setting a June 1, 2026 deadline.
• Hagens Berman said a class action has been filed that questions whether Gossamer hid problems at Latin American sites where heavily treated, lower‑risk patients did unusually well on placebo.
• The litigation follows Gossamer’s disclosure that its Phase 3 PROSERA study in pulmonary arterial hypertension failed to improve six‑minute walk distance, the trial’s main goal at 24 weeks.
• Company leaders said the overall treatment effect was diluted by an outsize placebo response and regional differences, with Latin America showing the strongest placebo gains.
• Gossamer’s shares fell about 80% after the results, and the company later said it has been below Nasdaq’s $1 minimum share price, putting its listing at risk.