Gossamer Bio Reacquires Seralutinib Rights, Plans NDA Submission

What Happened
Gossamer Bio (GOSS) announced on July 23, 2026 that it entered a Rights Reacquisition Agreement with Chiesi to terminate their May 3, 2024 License Agreement and reacquire worldwide development and commercial rights to seralutinib (including PAH and PH-ILD). Under the agreement Chiesi will pay Gossamer $5.0 million shortly after signing, Chiesi has assigned and licensed certain IP back to Gossamer, and Gossamer agreed to make success-based milestone payments and capped royalties to Chiesi in certain circumstances. Separately, following a mid‑June Pre‑NDA Type B meeting with the FDA (and receipt of meeting minutes), Gossamer said it plans to submit an NDA for seralutinib for pulmonary arterial hypertension in September 2026; if filed and accepted, an FDA decision could come in Q3 2027.

Key Details

• Rights Reacquisition Agreement signed July 23, 2026; it terminates the May 3, 2024 License Agreement with Chiesi.
• Chiesi will pay Gossamer $5.0 million within 10 days as reimbursement for development costs.
• Gossamer will owe success-based milestone payments and royalties on net sales up to a capped amount; certain IP licenses from Chiesi may be revoked if Gossamer breaches undisputed payment obligations (with cure periods).
• Gossamer estimates cash, cash equivalents and marketable securities of approximately $57.0 million as of June 30, 2026 (unaudited, preliminary).
• FDA characterized statistical significance/magnitude issues from PROSERA as review issues rather than filing issues; Gossamer intends to submit an NDA supported by Phase 3 PROSERA plus confirmatory Phase 2 TORREY data.

Why It Matters
This transaction restores full control of seralutinib to Gossamer, potentially increasing the company’s upside if the drug is approved and commercialized. The $5M payment from Chiesi provides near-term reimbursement, but Gossamer also takes on future milestone and royalty obligations (capped). The planned September 2026 NDA submission and the FDA’s feedback (as reflected in meeting minutes) set a concrete regulatory timeline—however, acceptance and approval are not guaranteed and will depend on the FDA’s full review. The company’s preliminary cash balance (~$57M) is a key metric for investors assessing near-term runway given development and potential commercial activities.