Gossamer Bio (NASDAQ: GOSS) shares rallied sharply on Monday after the clinical-stage biotech company said the U.S. Food and Drug Administration (FDA) provided feedback supporting a planned September filing for its lead drug candidate, seralutinib, while the company also regained full worldwide rights to the therapy.
The stock closed up 43.24% at $0.195 in regular trading and extended its rally after the bell, gaining another 40.27% to $0.280 in after-hours trading.
The company said it recently concluded a Pre-NDA Type B meeting with the FDA, with the agency’s written feedback supporting a planned September NDA submission for seralutinib in pulmonary arterial hypertension (PAH).
Gossamer Bio said the FDA considers questions surrounding the Phase 3 PROSERA trial’s statistical significance and treatment effect to be review matters rather than filing deficiencies, lowering the likelihood that the agency would refuse to file the application.
If the FDA accepts the NDA for review, Gossamer Bio said seralutinib could receive an approval decision in the third quarter of 2027.
Separately, Gossamer Bio regained exclusive worldwide rights to develop and commercialize seralutinib after ending its collaboration and licensing arrangement with Chiesi.
The transaction gives Gossamer Bio full control over the drug’s global development and commercialization, replacing the previous arrangement that included a 50/50 U.S. profit-sharing agreement and granted Chiesi rights outside the United States.
Under the terms of the agreement, Chiesi will make a one-time payment of $5 million to Gossamer Bio. The company said it will not pay any upfront cash to regain the rights. In return, Chiesi will receive capped royalties on future global net sales of seralutinib and milestone payments tied to specified regulatory and commercial achievements.
Gossamer Bio also pointed to recent efforts to strengthen its balance sheet. At a special meeting on July 14, shareholders approved proposals related to the completed exchange of the company’s 5.00% Convertible Senior Notes maturing in 2027. They also authorized the board to implement a reverse stock split if necessary.
The exchange transaction cut Gossamer Bio’s total outstanding debt by about $115.9 million. As of June 30, the company reported approximately $57 million in cash, cash equivalents, and marketable securities.
The regulatory update, combined with full ownership of seralutinib and an improved financial position, helped fuel strong buying interest in the stock during both regular and extended trading.
