By Colin Kellaher

Cytokinetics Inc. shares plunged more than 40% Thursday after a heart-failure drug it is developing with Amgen Inc. missed a key endpoint in a phase 3 study.

Amgen shares also moved lower.

The companies said the study of omecamtiv mecarbil met its primary composite endpoint of reduction in cardiovascular death or heart failure events but missed its secondary endpoint of reduction in cardiovascular death.

Analysts at Citi said the study results don't clear a commercial/clinical hurdle that Amgen and Cytokinetics had previously mentioned for the drug to be competitive, and that they doubt if Amgen would want to move forward with a launch.

Amgen and Cytokinetics said further analyses of the study data are underway, with results to be presented next month.

Cytokinetics shares were recently down 42.7% to $15.84, while Amgen shares shed 4.2% to $246.79.

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

(END) Dow Jones Newswires

10-08-20 1029ET