FDA Accepts Milestone Pharma’s CRL Response for CARDAMYST Nasal Spray; PDUFA Date Set for December 2025

Milestone Pharmaceuticals Inc. has announced that the U.S. Food and Drug Administration (FDA) has officially accepted its response to the Complete Response Letter (CRL) for CARDAMYST™ (etripamil) nasal spray. CARDAMYST is an investigational, fast-acting therapy intended for the treatment of paroxysmal supraventricular tachycardia (PSVT). The FDA has set a new Prescription Drug User Fee Act (PDUFA) action date of December 13, 2025.

Alongside this regulatory update, Milestone also confirmed the extension of its $75 million Royalty Purchase Agreement with RTW Investments, LP and affiliates until December 31, 2025. The funding is expected to support the planned commercial launch of CARDAMYST upon anticipated FDA approval and the fulfillment of standard closing conditions.

“The FDA’s acceptance is a major step forward for CARDAMYST. We remain committed to bringing this novel therapy to patients living with PSVT,” said Joe Oliveto, President and CEO of Milestone Pharmaceuticals. “RTW’s continued support reinforces our shared vision of transforming PSVT treatment.”

Amendment to RTW Royalty Agreement

Originally signed in March 2023, the Royalty Purchase Agreement with RTW Investments provided for the purchase of future U.S. sales royalties for $75 million, contingent on FDA approval by September 30, 2025. The newly announced amendment extends this deadline by three months, allowing Milestone until December 31, 2025 to secure FDA approval and meet other conditions to receive the funding.

Details of CRL and FDA Response Process

Milestone received the CRL in March 2025, following which a Type A meeting was held with the FDA in June 2025 to address outstanding regulatory issues. The company submitted its comprehensive response on June 13, 2025, including:

Additional in-vitro studies to address updated FDA guidelines on nitrosamines.
Manufacturing adjustments, including the reassignment of facility responsibilities to vendors recently inspected by the FDA, to meet pre-approval inspection requirements.

This progress brings Milestone one step closer to potential FDA approval and market launch of CARDAMYST, a therapy that could significantly benefit patients managing acute episodes of PSVT.