Gossamer Bio announced on March 19 that it will lay off approximately 48% of its workforce, affecting 77 employees, as part of a cost-saving initiative following the failure of its late-stage clinical trial for seralutinib, a drug candidate for pulmonary arterial hypertension.
The move comes after disappointing results from the Phase 3 PROSERA study last month, which has left the future of seralutinib uncertain and prompted the company to take steps to preserve cash. The layoffs were disclosed in Gossamer’s annual report filed on March 17.
“We depend entirely on the success of seralutinib,” the company said in its filing. “If we are unable to advance seralutinib in clinical development, obtain regulatory approval and ultimately commercialize seralutinib, or experience significant delays in doing so, our business will be materially harmed.”
It remains unclear when these job cuts will take effect or which locations will be impacted. Gossamer is headquartered in San Diego and also maintains an office in Dublin, Ireland. The company acknowledged potential risks associated with the staff reduction, stating that it could result in “unintended consequences and costs,” such as loss of institutional expertise and lowered morale among remaining employees. “We also may not realize the benefits expected from the workforce reduction,” Gossamer added, “including our ability to conserve cash, and such actions may make it more difficult to retain key personnel.”
The Phase 3 PROSERA study showed that patients treated with seralutinib had a 28.2-meter increase in a six-minute walk distance test compared to a 13.5-meter improvement for those receiving placebo; however, this difference did not reach statistical significance. Analysts at Guggenheim Partners told investors that the treatment effect was "well below what we believe could be considered clinically meaningful results." Following these results, Gossamer’s stock price dropped by 80% to $0.42 per share and has remained low since then.
As of December 31, 2025, Gossamer reported having $136.9 million in cash, cash equivalents and marketable securities.
