Gossamer Bio reported last month that its only late-stage candidate failed a Phase 3 study in pulmonary arterial hypertension, casting doubt on the asset’s future prospects.
After its disappointing late-stage readout in pulmonary arterial hypertension last month, Gossamer Bio has launched a sweeping cost-cutting campaign that will leave 77 employees—roughly 48% of its headcount—jobless.
The layoffs, revealed in Gossamer’s annual report on March 17, will help the company preserve cash as it figures out a way forward for its drug candidate, dubbed seralutinib, after the Phase 3 fail.
“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 is unclear when these layoffs will take effect, or which of Gossamer’s sites they will affect—the company is headquartered in San Diego, but also has an office in Dublin, Ireland. The biotech also said in its 2025 report that the staff cuts could have “unintended consequences and costs,” including 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.”
Gossamer’s drastic downsizing comes weeks after it announced that seralutinib failed the Phase 3 PROSERA study in pulmonary arterial hypertension. Patients treated with the drug showed a 28.2-meter increase in the six-minute walk distance test, while placebo comparators saw a 13.5-meter improvement. The overall treatment effect fell short of statistical significance.
Seralutinib didn’t just miss its primary target in PROSERA, but also demonstrated a treatment effect that fell “well below what we believe could be considered clinically meaningful results,” Guggenheim Partners told investors in a Feb. 23 note.
The failure sent Gossamer’s stocks plunging 80% to $0.42 apiece. The biotech has yet to recover from the drop, ending Wednesday’s trading session at $0.43 per share.
As of December 31, 2025, the biotech had $136.9 million in cash, cash equivalents and marketable securities.
