Verve Falls as Gene-Editing Trial Paused on Safety Issues (1)

Verve Therapeutics Inc. shares tumbled after it cited safety concerns for pausing enrollment in a study of its gene-editing treatment for people with high cholesterol, delivering a setback to the promising new field of medicine.

The Boston, Massachusetts-based company said the experimental approach lowered cholesterol levels in the first five participants who received a certain dose in the early-stage study, but the sixth developed abnormal liver enzymes and thrombocytopenia, a condition involving low blood platelet counts. The shares fell as much as 34% when US markets opened Tuesday.

Verve attributed the lab abnormalities, which resolved in a few days, ...