Milestone’s calcium channel blocker succeeded in a late-phase trial in China in people with an abnormal heart rhythm disorder, supporting ongoing efforts for an approval in the country as the FDA simultaneously reviews its US filing.
Etripamil is a self-administered nasal spray designed to treat paroxysmal supraventricular tachycardia (PSVT). The disorder causes unpredictable spikes in heart rates exceeding 150 to 200 beats per minute.
In the primary endpoint of the 500-participant Phase 3 trial in China, 40.5% of patients taking etripamil switched from PSVT to sinus rhythm within 30 minutes of treatment administration compared with 15.9% of placebo patients (p<0.001). The study also met key secondary endpoints of conversion to sinus rhythm by 10, 15, 45 and 60 minutes after treatment.
Safety-wise, side effects in this trial were consistent with previous studies of etripamil, and there were no serious adverse events related to the drug, according to a release on Friday.
Milestone’s partner Ji Xing is currently working toward an approval of etripamil in China, where it is responsible for overseeing the drug’s development and commercialization under the terms of a 2021 licensing agreement. That deal saw Ji Xing pay $15 million upfront, with Milestone receiving a further $5 million equity investment from RTW Investments.
Elsewhere, in May, the FDA accepted Milestone’s etripamil NDA, which included results from the company’s CARDAMYST trial program. The agency set a PDUFA date for March of next year.
Milestone’s first attempt at a US submission was met with a refuse-to-file action in December, prompting it to restructure certain datasets and reformat files earlier this year before making a second attempt.