Etripamil Nasal Spray shows positive topline results in Paroxysmal Supraventricular Tachycardia

Etripamil is an investigational intranasal calcium channel blocker. Etripamil has shown positive topline data announced from a phase 3 trial regarding its efficacy and safety in patients who experience an episode of paroxysmal supraventricular tachycardia (PSVT) in an at-home setting.The self-administered treatment more than doubled the rate of conversion to normal sinus rhythm versus placebo.

"PSVT is an unpredictable, disruptive burden on patients, with current interventions restricted to the costly and inconvenient acute care setting," said Bruce Stambler, M.D., F.H.R.S., Director of Cardiac Arrhythmia Research and Education, Piedmont Heart Institute, Atlanta, GA. "I am highly encouraged by the findings from the RAPID trial, which demonstrate that patients who administered etripamil converted to normal sinus rhythm significantly more often than placebo patients without experiencing serious adverse events, and independent of medical supervision.

These data further support the potential for etripamil to deliver a clinically meaningful benefit to patients and an important and valuable tool for their physicians."

"Today marks an important achievement for Milestone and for patients with PSVT," said Joseph Oliveto, President and Chief Executive Officer of Milestone Pharmaceuticals. "We believe that etripamil, if approved, has the potential to empower patients to take control of their condition as well as provide value to the healthcare system, in part by reducing visits to the Emergency Department.

We look forward to working with the U.S. Food and Drug Administration (FDA) to make available what we believe is the first of its kind, self-administered therapy. On behalf of the Milestone team, I would like to thank the patients, their caregivers, and the healthcare professionals who took part in the RAPID trial."

The multi-center, randomized, double-blind, placebo-controlled RAPID trial enrolled 706 patients across clinical sites in North America and Europe. Patients were randomized 1:1 to a nasal spray of either etripamil or placebo without medical monitoring. To maximize the potential treatment effect of etripamil, patients who did not experience symptom relief within 10 minutes were directed to self-administer a repeat dose of study drug.

The RAPID trial achieved its primary endpoint, with patients taking etripamil demonstrating a highly statistically significant and clinically meaningful difference in time to PSVT conversion compared to placebo.

A Kaplan Meier analysis shows a statistically significantly greater proportion of patients who took etripamil converted within thirty minutes compared to placebo (64.3% vs. 31.2%; hazard ratio [HR] = 2.62; 95% CI 1.66, 4.15; p<0.001). In addition, the median time to conversion for patients in RAPID who took etripamil was three times faster than for patients who took placebo. Statistically significant reductions in time to conversion in patients who took etripamil were evident early and persisted throughout the observation window of the study compared to placebo.

The safety and tolerability data from the RAPID trial continue to support the potential self-use of etripamil, with findings consistent with those observed in prior trials. The most common randomized treatment emergent adverse events (RTEAEs), adverse events (AEs) which occurred within 24 hours of study drug administration, were related to the nasal administration site. Overall, the majority of RTEAEs were reported as mild (68%) to moderate (31%). There were no reported serious AEs related to etripamil. To date, the Company's overall PSVT clinical program has resulted in more than 1,600 unique patient exposures of etripamil doses of ≥70 mg.

Analyses of pooled data from the NODE-301 and RAPID trials show that etripamil treatment provided a statistically significant reduction in the use of additional medical interventions, and a statistically significant reduction in visits to the emergency department.

Full results from the Phase 3 RAPID clinical trial are expected to be presented at an upcoming medical meeting and submitted to a peer-reviewed journal for publication.

As previously communicated, the Company believes results from the RAPID trial together with the data from the already completed NODE-301 trial could fulfill the efficacy requirement for a New Drug Application (NDA) submission for etripamil in patients with PSVT. The Company continues to enroll patients in the open label NODE-303 safety trial and plans to submit an NDA application in mid-2023 pending agency feedback.