Milestone Pharmaceuticals Inc (NASDAQ:MIST) shares gained 3.9% on Friday after the company announced that the first patient had been enrolled in its Phase 3 ReVeRA-301 study of etripamil for atrial fibrillation with rapid ventricular rate (AFib-RVR).
The late-stage trial represents an important step in Milestone’s efforts to expand the potential use of etripamil beyond paroxysmal supraventricular tachycardia (PSVT), where the treatment has already received US regulatory approval.
ReVeRA-301 evaluates 70 mg etripamil regimen
The ReVeRA-301 study will assess the same repeat-dose 70 mg etripamil regimen approved by the FDA for treating PSVT. For that indication, etripamil is marketed to adults as CARDAMYST nasal spray.
ReVeRA-301 is designed as a multinational, multicentre, randomised, double-blind and placebo-controlled Phase 3 trial involving approximately 150 patients with AFib-RVR.
Its primary endpoint will measure the reduction in ventricular rate within 30 minutes of treatment. A key secondary endpoint will assess improvements in symptoms using patient-reported outcomes.
Phase 3 programme builds on earlier positive results
The new study follows findings from the Phase 2 ReVeRA-201 trial, in which a single 70 mg dose of etripamil nasal spray reduced ventricular rates in patients experiencing AFib-RVR in an emergency room setting.
The earlier study also showed improvements in symptom relief and patient satisfaction with treatment, providing the clinical basis for advancing etripamil into Phase 3 development for the condition.
Milestone intends to pursue a supplemental New Drug Application through a single-study registration pathway for AFib-RVR.
Importantly, the company is developing the treatment for patient self-administration in medically unsupervised environments, including at home. This could potentially provide patients with an alternative way to manage episodes before seeking urgent medical care.
AFib-RVR represents substantial potential treatment market
Atrial fibrillation affects more than 6 million people in the United States, while market research cited by Milestone indicates that approximately 30% to 40% of AFib patients experience at least one rapid ventricular rate episode each year requiring urgent medical attention.
The wider economic burden associated with AFib is also expected to increase substantially over the coming decades.
According to projections from the American Heart Association, the total US economic cost of atrial fibrillation could rise from $59.4 billion in 2020 to $174.8 billion by 2050, measured in 2022 US dollars. Direct healthcare costs alone are projected to increase from $54.8 billion to $167.3 billion over the same period.
The start of ReVeRA-301 therefore marks a significant clinical milestone for Milestone as it seeks to establish etripamil as a potential self-administered treatment for AFib-RVR and broaden the commercial opportunity for its nasal spray platform.