Milestone Pharmaceuticals Inc announced that the U.S. Food and Drug Administration (FDA) has accepted for review Milestone’s response to issues raised in the Complete Response Letter (CRL) for CARDAMYST™ (etripamil) nasal spray, an investigational, novel therapy for the treatment of patients with paroxysmal supraventricular tachycardia (PSVT). The FDA has assigned a new Prescription Drug User Fee Act (PDUFA) target action date of December 13, 2025.
Concurrent with the FDA acceptance, Milestone is also announcing today the extension of its 75.0 million USD purchase and sale agreement (Royalty Purchase Agreement) with existing shareholder, RTW Investments, LP and certain of its affiliates (RTW) until December 31, 2025. The proceeds from the Royalty Purchase Agreement are expected to aid a successful planned launch of CARDAMYST in PSVT following expected FDA approval and satisfaction of other customary closing conditions.
“The FDA’s acceptance for review of our response to the CRL is a key milestone for CARDAMYST and we look forward to working with the Agency toward a potential approval decision later this year,” said Joe Oliveto, President and Chief Executive Officer of Milestone Pharmaceuticals. “We are also pleased to amend our Royalty Purchase Agreement with RTW, underscoring their ongoing commitment to Milestone. The anticipated funds will position us well to execute on the commercial launch as we work to get CARADMYST into the hands of patients with PSVT in need of a new treatment.”
Amendment of Royalty Purchase Agreement with RTW
In March 2023, Milestone entered into the Royalty Purchase Agreement with RTW, pursuant to which RTW agreed to purchase, following the FDA approval (subject to certain conditions) of etripamil on or prior to September 30, 2025 (Approval Date), the right to receive a tiered royalty payments on the annual net product sales of etripamil in the United States, in exchange for a purchase price of 75.0 million USD. On July 10, 2025, Milestone has amended its Royalty Purchase Agreement (the Amendment) to provide for a three-month extension of the Approval Date. Pursuant to the Amendment, in order to receive the 75 million USD purchase price, Milestone must receive marketing approval of etripamil from the FDA on or prior to December 31, 2025, satisfy the other customary closing conditions. This represents a contingent future source of funding for Milestone.
Milestone Response to the CRL
Milestone received a Complete Response Letter (CRL) from the FDA in March 2025. A Type A meeting was held with the Agency in early June 2025 to clarify the outstanding items and reach alignment with the FDA on the requirements for the Company’s response to the CRL. Informed by the FDA meeting, Milestone submitted the response to the CRL on June 13, 2025. Included in that response were the results of additional in-vitro studies conducted to meet the updated FDA guidance on nitrosamines, which had been updated since the original NDA submission. Further, in response to the FDA’s need to conduct a pre-approval inspection of a manufacturing testing facility, Milestone transferred the duties of that facility to other contracted vendors that have a relatively recent inspection history with FDA.
