Gossamer Bio (NASDAQ:GOSS) said it plans to submit a New Drug Application, or NDA, to the U.S. Food and Drug Administration in September 2026 for seralutinib in pulmonary arterial hypertension, or PAH, following a pre-NDA Type B meeting with the agency.
The company said FDA meeting minutes characterized the statistical significance and magnitude of the treatment effect in the Phase III PROSERA study as review issues rather than filing issues. The agency has not accepted an NDA for filing or completed a substantive review, Gossamer said.
Planned NDA Evidence Package
Gossamer intends to base its submission on PROSERA as an adequate and well-controlled Phase III trial, supplemented by confirmatory evidence from the separate randomized, placebo-controlled TORREY study and other supportive analyses.
Peterson said FDA will assess the efficacy and safety data, clinical meaningfulness of the treatment effect, statistical significance and overall risk-benefit profile during review of the complete application. She also said the company did not discuss a potential advisory committee meeting with FDA and would not expect to learn whether one may be convened until the middle of the review.
In response to questions about further data disclosure, management said it expects to present additional subgroup and translational medicine analyses at major medical meetings, including the European Respiratory Society meeting. Peterson said prespecified subgroup analyses related to continued disease burden support seralutinib’s efficacy, while functional respiratory imaging analyses support an effect on disease pathology.
Management said it plans to seek a broad PAH indication, though the final label would be subject to negotiations with FDA later in the review. The company said PROSERA’s intent-to-treat population will form the basis of the NDA, with subgroups providing supportive evidence.
Worldwide Rights Reacquired From Chiesi
Gossamer also announced that it reacquired worldwide development and commercial rights to seralutinib from Chiesi. Chief Executive Officer Faheem Hasnain said the transaction gives Gossamer global strategic and operational control over regulatory, manufacturing, pricing, market access, commercialization and lifecycle-development decisions.
Under the new arrangement, Gossamer said it will retain the substantial majority of seralutinib’s worldwide economics without making an upfront cash payment. Chiesi is expected to make a $5 million payment to Gossamer shortly after signing, according to the company.
Chiesi will retain a capped royalty on worldwide net sales and certain success-based milestone payments. Hasnain said the structure replaces the prior arrangement, under which Gossamer and Chiesi shared U.S. profits equally and Gossamer participated in ex-U.S. sales through a royalty.
Management said Chiesi’s remaining financial participation is contingent on commercial sales and specified milestones. During the question-and-answer session, executives attributed the transaction in part to Chiesi’s evolving strategic focus toward very rare and ultra-orphan diseases.
Gossamer said it intends to proceed as an independent company for commercialization at this time. Commercial Officer Robert Smith said the company had slowed launch-readiness activities after the release of top-line data to preserve capital, but expects to resume those efforts during the second half of 2026 in preparation for a potential U.S. launch in August or September 2027.
Capital Structure Actions and Cash Position
At a July 14, 2026 special meeting, stockholders approved proposals related to Gossamer’s previously completed exchange of its 5% convertible senior notes due 2027 and authorized the board to implement a reverse stock split.
- Approximately $181.1 million of the original $200 million principal amount of 2027 notes was exchanged.
- The exchanged notes were replaced with approximately $65.2 million of 7.5% convertible secured notes due 2030, along with applicable equity securities and warrants.
- The transaction reduced aggregate debt principal by approximately $115.9 million, according to the company.
Chief Financial Officer and Chief Operating Officer Bryan Giraudo said the reverse-split authorization is intended to support Nasdaq minimum bid-price compliance and provide capital-structure flexibility. The timing and ratio of any reverse split remain subject to final board action.
As of June 30, 2026, Gossamer reported approximately $57 million in cash equivalents and marketable securities.
Potential Expansion Beyond PAH
Management also discussed potential development in pulmonary hypertension associated with interstitial lung disease, or PH-ILD. Hasnain said the company has increased conviction in that opportunity based on results in connective-tissue-disease subgroups from PROSERA.
Gossamer said it would look to initiate a PH-ILD study after a potential PAH approval. If FDA requires additional post-approval confirmatory evidence for PAH, the company said a PH-ILD study could potentially be considered within that confirmatory process, subject to further discussions with the agency.
The company said it also intends to pursue regulatory discussions outside the U.S., including in Europe, after prioritizing the FDA process. Management estimated that the European regulatory pathway is approximately one year behind the U.S. timeline.
About Gossamer Bio (NASDAQ:GOSS)
Gossamer Bio, Inc is a clinical-stage biopharmaceutical company headquartered in San Diego, California. Founded in 2012, the company is focused on discovering and developing oral, once-daily therapies for immune-mediated and inflammatory diseases, as well as oncology indications. Gossamer Bio leverages a deep pipeline of small-molecule candidates aimed at improving patient outcomes in areas of high unmet need.
The company’s lead programs include GB004, an S1P1 receptor modulator in late-stage development for ulcerative colitis, and GB1275, a CD11b modulator being investigated in solid tumors and hematologic malignancies.
-ELIZA.png){kind=small}
