By Colin Kellaher


Shares of Avidity Biosciences Inc. tumbled more than 20% on Tuesday after the U.S. Food and Drug Administration placed a partial clinical hold on a Phase 1/2 study of its lead product candidate.

The San Diego biopharmaceutical company said the partial hold, which came after one participant suffered a serious adverse event, stops enrollment of new study participants.

Avidity said current participants in the study of AOC 1001 in adults with the genetic disorder myotonic dystrophy type 1 can continue treatment, and that it is working to assess the cause of the adverse event and to resolve the partial hold.

Evercore ISI analyst Josh Schimmer said the partial hold adds a wrinkle to the study, but that it sounds transient.

In a research note, the analyst said the cause of the hold seems to have a limited impact, as the FDA also gave Avidity the green light to proceed with studies of AOC 1020 for the treatment of facioscapulohumeral muscular dystrophy and AOC 1044 in Duchenne muscular dystrophy.

Mr. Schimmer said he is currently making no changes to his outperform rating and $35 price target on Avidity shares, which were recently changing hands at $14.42, down 23%.


Write to Colin Kellaher at colin.kellaher@wsj.com


(END) Dow Jones Newswires

09-27-22 1012ET