US FDA Declines to Approve Milestone’s Heart Rhythm Nasal Spray

(Reuters) -Milestone Pharmaceuticals said on Friday that the U.S. health regulator had declined to approve its nasal spray to treat a type of heart condition and had called for an inspection of the facility that performs the testing of the drug.

Shares of the company more than halved to 95 cents in premarket trading.

The Food and Drug Administration (FDA), in its so-called complete response letter, has also sought additional data on nitrosamine impurities, based on new guidance that was issued after the company had submitted its application for Cardamyst’s approval.

Nitrosamine impurities may increase the risk of cancer if people are exposed to them above acceptable levels and over long periods of time.

The FDA highlighted two key chemistry, manufacturing and controls issues related to the spray, called Cardamyst, but did not raise any concerns about its safety or efficacy.

The FDA’s decision marks another setback for the company after it previously received a “refusal to file” letter from the agency in December 2023, upon which the company resubmitted the marketing application for Cardamyst with changes for substantial review.

The agency in its letter said the inspection at a facility that performs release testing for Cardamyst was required to ensure it is in compliance with current good manufacturing practices.

The facility changed ownership during the review of the drug, the company said.

Milestone said the self-administered nasal spray helped a significantly greater proportion of patients return to normal heart rhythm compared to a placebo in a late-stage study.

The spray for the treatment of paroxysmal supraventricular tachycardia (PSVT), which causes abnormal heart rhythm, is characterized by episodes of sudden-onset rapid heartbeats, often exceeding 150 to 200 beats per minute.

An estimated two million people in the U.S. are currently diagnosed with PSVT, the company said.

(Reporting by Siddhi Mahatole and Puyaan Singh in Bengaluru; Editing by Shreya Biswas, Maju Samuel and Shailesh Kuber)