Seralutinib (GB002) - (TORREY/PROSERA)

July 27, 2026: Gossamer Bio, Inc. (NASDAQ: GOSS) reported regulatory, strategic, and financing updates centered on seralutinib (GB002), an inhaled PDGFR/CSF1R/c-KIT inhibitor for pulmonary arterial hypertension (PAH) (and being developed in PH-ILD).

Seralutinib (PAH) regulatory catalyst: Following a mid-June 2026 Pre-NDA Type B meeting and receipt of FDA meeting minutes, Gossamer said it is proceeding toward a planned NDA submission in September 2026. Per the minutes, FDA viewed the statistical significance and magnitude of effect in the Phase 3 PROSERA study as review issues rather than filing issues. The planned NDA is expected to be supported by one adequate and well-controlled study (PROSERA) plus confirmatory evidence (Phase 2 TORREY and supportive analyses). If the NDA is accepted, the company said seralutinib could be eligible for an FDA approval decision in Q3 2027.

Business development: Gossamer and Chiesi terminated their collaboration, with Gossamer reacquiring worldwide development and commercial rights to seralutinib. Chiesi will pay Gossamer $5 million; Chiesi will receive a capped royalty on worldwide net sales plus specified regulatory/commercial milestone payments.

Capital structure: Stockholders approved proposals related to a convertible note exchange and authorized a reverse stock split (expected in or shortly after Q3 2026). Preliminary cash balance was ~$57 million as of June 30, 2026.