Etripamil

Established in Montreal 22 years ago, Milestone Pharmaceuticals still has work to do to gain its first FDA approval as the regulator has sent a complete response letter, citing two manufacturing issues for Cardamyst, a nasal spray to treat sudden episodes of the heart racing condition paroxysmal supraventricular tachycardia (PSVT). Clearing clinical and regulatory hurdles in the development of a fast-acting nasal spray for a heart condition has been a challenge for Milestone Pharmaceutical in its 22 years.Now the wait will be longer for its first FDA approval as the regulator has rejected its application for Cardamyst (etripamil) to quell symptomatic episodes from paroxysmal supraventricular tachycardia (PSVT), which is a type of abnormal heart rhythm.In a complete response letter (CRL), the FDA cited two chemistry, manufacturing and control (CMC) issues. Milestone will have to address a problem with nitrosamine impurities. An FDA inspection also will be required at a facility that performs “release testing” for the drug, the company said in a release. During the FDA’s review of Milestone’s application, the manufacturing facility “changed ownership,” the company said.“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,” Joe Oliveto, Milestone’s CEO for the last eight years, said in a statement. “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 said that the FDA did not raise any concerns with Cardamyst’s clinical safety or efficacy. The company opened the year with cash and cash equivalents of $70 million.With an approval, Cardamyst would become the first self-administered treatment patients can use to manage their PSVT symptoms. The calcium channel blocker is designed to be a more convenient alternative to an emergency room visit, where patients receive an intravenous dose of a drug that “basically reboots your heart,” Oliveto said in an interview two weeks ago.Results from a phase trial have shown that Cardamyst was twice as effective and worked three times as fast as a placebo in restoring normal heart rhythm. Of the patients on etripamil, 64% achieved termination of their PSVT compared to 31% of those on placebo.Getting that result took some time, however, after a phase 3 trial in 2020 came up short as Cardamyst failed to top placebo. After discussions with the FDA, Milestone got improved results when it allowed patients to use a second dose and adjusted to a shorter timeframe (30 minutes) for measuring the success of the treatment.There are roughly 2 million in the U.S. with PSVT. Beyond that, Milestone is hoping to gain approval for Cardamyst in a larger indication—atrial fibrillation with rapid ventricular response (AFib-RVR), which includes approximately 10–12 million U.S. patients.

Milestone Pharmaceuticals’ nasal spray failed for a second time to secure US approval to treat an arrhythmia disorder called paroxysmal supraventricular tachycardia. The FDA’s complete response letter identified two CMC issues, according to Friday’s release . Milestone said it has to provide more information about “nitrosamine impurities,” saying the FDA issued new draft guidance after it filed its NDA. It also said the facility that conducts release testing for etripamil will need to be inspected after a change in ownership during the review period. Milestone said the agency didn’t raise any concerns about drug efficacy or safety. Even so, the company’s shares $MIST plummeted about 60% on Friday morning. Milestone’s path to the FDA has been filled with setbacks. It previously tried to file for approval of etripamil in 2023 but received a refuse-to-file letter from the FDA at the end of that year. The agency requested more information about the “time of data recorded for adverse events” in the company’s registrational studies. In 2020, etripamil failed a Phase 3 trial in PSVT. Milestone’s latest NDA was based on results from two Phase 3 studies called RAPID and NODE-301. In the RAPID trial, almost 65% of patients given etripamil switched to sinus rhythm — or a regular heartbeat — within 30 minutes of treatment, versus 31.2% of placebo patients, according to topline results shared by Milestone in 2022. The data were statistically significant. Etripamil is a calcium channel blocker formulated as a self-administered nasal spray. Patients with paroxysmal supraventricular tachycardia, or PSVT, who have a sudden onset of rapid heartbeats often need immediate medical attention, which may include a trip to the emergency room. Milestone’s drug is meant to treat patients quickly and help them avoid an ER visit. The company had been preparing for a “staged launch” of etripamil in PSVT starting in the middle of this year, according to TD Cowen analysts in February. The plan had been to initially target 10,000 to 12,000 physicians, mostly cardiologists. The disease is estimated to have a prevalence of less than 1% in the US. That said, the company believes that atrial fibrillation represents a much larger market opportunity for the drug, Milestone CEO Joseph Oliveto said at the TD Cowen Health Care Conference in Boston in February. Etripamil is currently in Phase 2 development for atrial fibrillation. In September of last year, the drug passed a Phase 3 test in patients in China with PSVT, setting the stage for a filing by Milestone’s China partner Ji Xing.