Milestone Pharmaceuticals Announces First European Study Participant Enrolled in ReVeRA-301 Phase 3 Clinical Trial

Milestone is pursuing a single-study registration pathway to add AFib-RVR treatment to etripamil’s existing PSVT indication.

Rhea-AI Summary

Milestone Pharmaceuticals (MIST) enrolled its first European participant in ReVeRA-301, the Phase 3 trial evaluating etripamil nasal spray for AFib-RVR.

The participant enrolled through the Dutch Cardiovascular Investigator Network in the Netherlands. U.S. enrollment began in August 2026 and has expanded to Canada. The randomized, double-blind, placebo-controlled study targets approximately 150 treated patient events involving atrial fibrillation with rapid ventricular rate, or AFib-RVR. Patients will self-administer a 70 mg repeat-dose regimen in medically unsupervised settings. The primary endpoint is reduction in ventricular rate within 30 minutes; a key secondary endpoint measures patient-reported symptom improvement.

Milestone is pursuing a single-study supplemental new drug application pathway for AFib-RVR based on safety data to date. The regimen is already FDA-approved as CARDAMYST for PSVT, a different fast-heartbeat condition.

4 points · 0 major

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Hollow bars mark forward-looking points. How the balance works

Positive

• Moderate point. Forward-looking: it has not happened yet and may not happen.Milestone is pursuing a single-study supplemental new drug application pathway for AFib-RVR based on safety data to date.
• Moderate pointPhase 2 ReVeRA-201 found 70 mg single-dose etripamil reduced ventricular rate and improved symptom relief and treatment satisfaction.
• Minor pointReVeRA-301 enrolled its first European participant through the Dutch Cardiovascular Investigator Network.
• Minor pointEnrollment expanded to Canada after starting in the United States in August 2026.

Negative

• None.

Key Figures

Trial phase: Phase 3 Target enrollment: Approximately 150 patients Repeat-dose regimen: 70 mg +2 more

Trial phase

Phase 3

ReVeRA-301 for AFib-RVR

Target enrollment

Approximately 150 patients

AFib-RVR patients with treated AFib-RVR events

Repeat-dose regimen

70 mg

ReVeRA-301 etripamil regimen

Primary endpoint timing

Within 30 minutes

Reduction in ventricular rate

Registration pathway

Single-study sNDA

Pathway being pursued for AFib-RVR

Previous Clinical trial Reports

2 past events · Latest: Sep 24

Same Type 2 events

1. Sep 24

   Phase 3 enrollment

   24h Move

   -8.2%

   First Canadian participant enrolled in ReVeRA-301 at the Montreal Heart Institute.

2. Aug 21

   Phase 3 initiation

   24h Move

   +2.4%

   ReVeRA-301 began as a pivotal trial targeting approximately 150 AFib-RVR patients.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Key Terms

afib-rvr, double-blind, placebo-controlled, supplemental new drug application, +1 more

5 terms

afib-rvr medical

"atrial fibrillation with rapid ventricular rate (AFib-RVR)"

Atrial fibrillation with rapid ventricular response (afib‑rvr) is a common heart rhythm problem where the heart’s upper chambers beat chaotically and the lower chambers respond by beating very fast, like an engine revving uncontrollably. It matters to investors because it often leads to urgent care, hospitalization, long‑term treatment or procedures, and higher healthcare costs, which can affect demand for drugs, devices, hospital services, insurance payouts and clinical trial outcomes.

double-blind technical

"randomized, double-blind, placebo-controlled study"

A double-blind process means that neither the people conducting an activity nor the people involved know certain key details, such as who is receiving a treatment or a placebo. This approach helps prevent bias from influencing the results, making the outcome more trustworthy. For investors, it ensures that decisions or judgments are based on unbiased information rather than preconceived opinions or expectations.

placebo-controlled technical

"randomized, double-blind, placebo-controlled study"

"Placebo-controlled" describes a testing method where one group receives the actual treatment or intervention, while another group receives a harmless, inactive version called a placebo. This approach helps determine whether the real treatment has genuine effects beyond psychological expectations. For investors, understanding this ensures confidence that reported benefits are real and not influenced by bias or false perceptions.

supplemental new drug application regulatory

"pursuing a single-study supplemental new drug application (sNDA) registration pathway"

A supplemental new drug application is a request submitted to regulatory authorities to make changes to an existing approved medication, such as adding new uses, strengths, or formulations. For investors, it signals that a pharmaceutical company is seeking approval for new product developments or expanded applications, which can impact the company's future sales, market potential, and stock value.

primary endpoint medical

"The primary endpoint for ReVeRA-301 is reduction in ventricular rate"

The primary endpoint is the single main result a clinical study is designed to measure to decide if a treatment works, like the finish line in a race that tells you who won. Investors care because meeting or missing this goal drives regulatory decisions, future sales expectations and stock value — it turns trial data into a clear yes-or-no signal about a drug’s commercial prospects.

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Dutch Cardiovascular Investigator Network (WCN) Leads European Enrollment in Phase 3 Study Evaluating Etripamil Nasal Spray for AFib-RVR

MONTREAL and CHARLOTTE, N.C., Oct. 09, 2026 (GLOBE NEWSWIRE) -- Milestone^® Pharmaceuticals Inc. (Nasdaq: MIST), a biopharmaceutical company focused on the development and commercialization of innovative cardiovascular medicines, today announced that the first European patient has been enrolled in ReVeRA-301, its ongoing Phase 3 pivotal trial evaluating etripamil nasal spray for the treatment of atrial fibrillation with rapid ventricular rate (AFib-RVR). The study participant was enrolled at a site within the Dutch Cardiovascular Investigator Network (WCN) in the Netherlands as enrollment advances toward the study’s target of approximately 150 AFib-RVR patients with treated AFib-RVR events. ReVeRA-301 is evaluating the same 70 mg repeat-dose regimen that is U.S. Food and Drug Administration (FDA)-approved for the treatment of paroxysmal supraventricular tachycardia (PSVT) as CARDAMYST^® (etripamil) nasal spray. 

“Enrollment of the first patient in Europe represents continued progress in the global execution of ReVeRA-301 as we advance our pivotal Phase 3 program,” said David Bharucha, M.D., PhD, FACC, Chief Medical Officer of Milestone Pharmaceuticals. “WCN brings an established network of experienced cardiovascular investigators, and our collaboration during the successful Phase 2 ReVeRA study in AFib-RVR provides a strong foundation for this next stage of clinical development. We look forward to building on that experience as we evaluate etripamil as a potential self-administered, ambulatory-setting treatment for patients experiencing AFib-RVR.”

“The enrollment of the first European patient in ReVeRA-301 marks an important milestone in advancing a new potential treatment for patients with AFib-RVR. This innovative study explores a novel approach that could help patients receive effective treatment earlier and potentially avoid hospital visits. We are proud that the Dutch WCN network can support both participating sites and Milestone Pharmaceuticals in bringing this exciting trial to patients,” said Martin Hemels, M.D., PhD, FEHRA, FESC, Cardiologist and Chair of WCN, the Dutch Cardiovascular Investigator Network.

Enrollment in ReVeRA-301 in the United States commenced in August 2026 and has since expanded to Canada.

About ReVeRA-301 

ReVeRA-301 is a Phase 3 multinational, multi-center, randomized, double-blind, placebo-controlled study to evaluate the effects of etripamil nasal spray in approximately 150 patient events with AFib-RVR. Prompted by symptoms, patients will self-administer, in a medically unsupervised setting (e.g., at home), the same 70 mg dose of etripamil and repeat-dose regimen that supports the current FDA indication for the treatment of PSVT. Based on safety data demonstrated to date, Milestone is currently pursuing a single-study supplemental new drug application (sNDA) registration pathway for the treatment of AFib-RVR. The primary endpoint for ReVeRA-301 is reduction in ventricular rate (VR) within 30 minutes. The study will also evaluate a key secondary endpoint of symptom improvement via patient-reported outcomes. Clinical trial sites and enrollment information can be found at https://clinicaltrials.gov. 

The trial advances research from ReVeRA-201, a multi-center Phase 2, randomized controlled study of the efficacy and safety of etripamil nasal spray for the acute reduction of symptomatic AFib-RVR in an emergency room setting. The clinical trial showed that a single dose of etripamil nasal spray at 70 mg reduced VR and improved both relief of symptoms and treatment satisfaction.

About Atrial Fibrillation with Rapid Ventricular Rate (AFib-RVR)

Atrial fibrillation (AFib) represents a substantial and growing public health burden. The most common sustained arrhythmia, AFib affects an estimated 59 million people worldwide, including people in the European Union. AFib presents with an irregular heart rate and is classified as paroxysmal, persistent, or permanent. When there is a rapid heart rate during AFib, it is referred to as “atrial fibrillation with rapid ventricular rate (AFib-RVR).”

Market research indicates that 30-40% of patients with AFib experience at least one episode of RVR per year requiring urgent medical attention. These episodes commonly cause palpitations, shortness of breath, and weakness. While AFib is rarely life-threatening, it is a serious condition that often requires treatment and increases the risk of serious complications if not properly managed. Current options for acute AFib-RVR management are limited and often involve an emergency department visit for IV beta blockers, IV calcium channel blockers, or electrical cardioversion. 

About CARDAMYST in the United States 

CARDAMYST^® (etripamil) nasal spray is approved by the U.S. Food and Drug Administration (FDA) for the conversion of acute symptomatic episodes of paroxysmal supraventricular tachycardia (PSVT) to sinus rhythm in adults. It is a novel calcium channel blocker nasal spray designed as a self-administered rapid response therapy for patients, thereby bypassing the need for immediate medical oversight. The product is intended to provide health care providers with a new treatment option to enable on-demand care and patient self-management. This portable treatment may provide patients with active management and a greater sense of control over their condition. CARDAMYST is well studied with a robust clinical trial program that includes a completed Phase 3 clinical-stage program for the treatment of PSVT. Currently, etripamil is in Phase 2 development for treatment of PSVT in pediatric patients and Phase 3 development for control of acute atrial fibrillation with rapid ventricular rate (AFib-RVR) in adults. For more information, please visit CARDAMYST.com. 

U.S. FDA Indication
CARDAMYST is indicated for the conversion of acute symptomatic episodes of paroxysmal supraventricular tachycardia (PSVT) to sinus rhythm in adults.

IMPORTANT SAFETY INFORMATION FOR CARDAMYST (etripamil)

What is CARDAMYST?

CARDAMYST is a prescription medicine used to help restore normal sinus heart rhythm in adults who have symptoms of sudden episodes of fast heartbeat called paroxysmal supraventricular tachycardia (PSVT).

It is not known if CARDAMYST is safe and effective in children.

Do not use CARDAMYST if you:

• are allergic to CARDAMYST or any of its ingredients. See the Patient Information for a complete list of ingredients in CARDAMYST.
• have limitations in activities due to heart failure (moderate to severe heart failure).
• have Wolff-Parkinson-White (WPW) syndrome, Lown-Ganong-Levine syndrome, or an abnormal heart rhythm pattern called pre-excitation (delta wave) on an electrocardiogram (ECG).
• have sick sinus syndrome without a permanent pacemaker.
• have second degree or higher atrioventricular (AV) block.
  
  

Before using CARDAMYST, tell your healthcare provider about all of your medical conditions, including if you:

• have a history of fainting.
• have low blood pressure.
• are pregnant or plan to become pregnant. It is not known if CARDAMYST will harm your unborn baby.
• are breastfeeding or plan to breastfeed. It is not known if CARDAMYST passes into your breast milk. You should stop breastfeeding for 12 hours after treatment with CARDAMYST. During this time, pump and throw away your breast milk. Talk to your healthcare provider about the best way to feed your baby after using CARDAMYST.
  
  

Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements.

What are the possible side effects of CARDAMYST?

CARDAMYST may cause serious side effects, including:

• Fainting due to CARDAMYST effects on blood pressure, heart rate, and electrical activity of the heart. CARDAMYST may cause dizziness and fainting, especially in people with a history of fainting and certain heart problems, or people with a history of fainting during an episode of PSVT. Use CARDAMYST while sitting in a safe area where you will not fall if you become dizzy or lightheaded. Lie down if you feel dizzy or lightheaded after using CARDAMYST. If fainting occurs after using CARDAMYST, caregivers should place you on your back and seek medical help.
  
  

The most common side effects of CARDAMYST include:

nasal discomfort nasal congestion runny nose

throat irritation nosebleed

These are not all of the possible side effects for CARDAMYST. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Please see the full Prescribing Information 
https://milestonepharma.com/etripamilprescribinginformation.pdf for CARDAMYST.

About Milestone Pharmaceuticals
Milestone Pharmaceuticals Inc. (Nasdaq: MIST) is an emerging commercial-stage biopharmaceutical company advancing innovative cardiovascular medicines to benefit people living with certain heart conditions. Milestone’s lead product is CARDAMYST^® (etripamil) nasal spray, a novel calcium channel blocker, which is FDA-approved for the conversion of acute symptomatic episodes of paroxysmal supraventricular tachycardia (PSVT) to sinus rhythm in adults. Etripamil is also in Phase 3 development for the control of symptomatic episodic attacks associated with AFib-RVR. https://milestonepharma.com/.

Cautionary Note on Forward-Looking Statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as “believe,” “continue,” “could,” “demonstrate,” “designed,” “develop,” “estimate,” “expect,” “may,” “pending,” “plan,” “potential,” “progress,” “will,” “intend” and similar expressions (as well as other words or expressions referencing future events, conditions, or circumstances) are intended to identify forward-looking statements. These forward-looking statements are based on Milestone’s expectations and assumptions as of the date of this press release. Each of these forward-looking statements involves risks and uncertainties. Actual results may differ materially from these forward-looking statements. Forward-looking statements contained in this press release include statements regarding: Milestone's business strategy and plans; the design, timing, and enrollment of the ReVeRA-301 Phase 3 clinical trial for AFib-RVR, including the anticipated number of patients and sites; the potential for etripamil to serve as a treatment option for patients with AFib-RVR, including as a self-administered therapy; the commercialization and market adoption of CARDAMYST; the development of etripamil for additional indications, including Phase 2 development in pediatric PSVT patients; expectations regarding the efficacy and safety of etripamil for AFib-RVR based on Phase 2 findings; the timing and outcomes of future interactions with U.S. and foreign regulatory bodies, including the FDA; and other statements not related to historical facts. Important factors that could cause actual results to differ materially from those in the forward-looking statements include, but are not limited to, the risks inherent in biopharmaceutical product development and clinical trials, including the lengthy and uncertain regulatory approval process; uncertainties related to the timing of initiation, enrollment, completion, evaluation and results of Milestone’s clinical trials; risks and uncertainty related to the complexity inherent in cleaning, verifying and analyzing trial data; and whether the clinical trials will validate the safety and efficacy of etripamil for PSVT or other indications, among others, general economic, political, and market conditions, including deteriorating market conditions due to investor concerns regarding inflation, international tariffs and conflicts, and overall fluctuations in the financial markets in the United States and abroad, risks related to pandemics and public health emergencies, and risks related to the sufficiency of Milestone’s capital resources and its ability to raise additional capital in the current economic climate. These and other risks are set forth in Milestone’s filings with the U.S. Securities and Exchange Commission (SEC), including in its annual report on Form 10-K for the year ended December 31, 2025, under the caption “Risk Factors,” as such discussions may be updated from time to time by subsequent filings Milestone may make with the SEC. Except as required by law, Milestone assumes no obligation to update any forward-looking statements contained herein to reflect any change in expectations, even as new information becomes available.

Contact:

Investor Relations
Kevin Gardner, kgardner@lifesciadvisors.com

Media Relations
Rebecca Novak, rnovak@milestonepharma.com 

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What does Milestone’s ReVeRA-301 Phase 3 trial measure?

ReVeRA-301’s primary endpoint is reduction in ventricular rate within 30 minutes in patients with AFib-RVR. The randomized, double-blind, placebo-controlled trial targets approximately 150 treated patient events and also evaluates patient-reported symptom improvement as a key secondary endpoint.

Where was Milestone’s first European ReVeRA-301 participant enrolled?

The first European participant enrolled at a site within the Dutch Cardiovascular Investigator Network in the Netherlands. Enrollment began in the United States in August 2026 and has also expanded to Canada.

What did Milestone’s earlier ReVeRA-201 trial show for AFib-RVR?

ReVeRA-201 showed that a single 70 mg dose of etripamil nasal spray reduced ventricular rate and improved symptom relief and treatment satisfaction. The randomized controlled Phase 2 study evaluated acute treatment of symptomatic AFib-RVR in an emergency room setting.