FDA Issues Complete Response Letter for Etripamil for PSVT

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Milestone Pharmaceuticals Inc.
Milestone Pharmaceuticals Inc.

CRL focused on CMC; no clinical issues relating to etripamil raised

$69.7M in cash, cash equivalents and short-term investments as of December 31, 2024 

MONTREAL and CHARLOTTE, N.C., March 28, 2025 (GLOBE NEWSWIRE) -- Milestone® Pharmaceuticals Inc. (Nasdaq: MIST) today announced the U.S. Food and Drug Administration (FDA) issued a Complete Response Letter (CRL) regarding its New Drug Application (NDA) for CARDAMYST™ (etripamil) nasal spray, a prescription medication in development for the conversion of acute episodes of PSVT to sinus rhythm in adults.

The FDA did not raise any concerns regarding etripamil clinical safety or efficacy data and highlighted two key Chemistry, Manufacturing and Controls (CMC) issues to be addressed:

  • Company to submit additional information on nitrosamine impurities based on new draft guidance issued after the NDA submission; and

  • An inspection is required at a facility that performs release testing for etripamil, to ensure it is in compliance with Current Good Manufacturing Practices. The facility changed ownership during the review of the NDA.

“We are deeply disappointed by the CRL but remain committed to the potential of CARDAMYST as a novel treatment option that can help patients with PSVT. Our team is evaluating the feedback provided and intends to request a Type A meeting to discuss the issues raised in the CRL,” said Joe Oliveto, President and Chief Executive Officer of Milestone Pharmaceuticals. “We are appreciative of the FDA’s efforts and are confident we can collaborate with the agency with the goal of addressing these issues in a resubmission.”

Milestone Pharmaceuticals had $69.7M in cash, cash equivalents and short-term investments as of December 31, 2024.

About Etripamil

Etripamil is Milestone's lead investigational product. It is a novel calcium channel blocker nasal spray under clinical development for frequent and often highly symptomatic episodes of PSVT and AFib-RVR. It is designed as a self-administered rapid response therapy for patients thereby bypassing the need for immediate medical oversight. If approved, etripamil is intended to provide health care providers with a new treatment option to enable on-demand care and patient self-management. This portable, self-administered treatment may provide patients with active management and a greater sense of control over their condition. CARDAMYST™, the conditionally approved brand name for etripamil nasal spray, is well studied with a robust clinical trial program that includes a completed Phase 3 clinical-stage program for the treatment of PSVT and Phase 2 trial for the treatment of patients with AFib-RVR.