AstraZeneca shares experienced a sharp decline following the disappointing announcement that its experimental heart-disease drug, Wainua, failed to meet its primary objectives in a highly anticipated late-stage clinical trial.

The Phase III CARDIO-TTRansform trial, conducted in partnership with Ionis Pharmaceuticals, evaluated Wainua as a treatment for transthyretin-mediated amyloid cardiomyopathy, a progressive and potentially fatal cardiovascular condition. The trial failed to show a statistically significant benefit in reducing cardiovascular mortality and recurrent clinical events over 140 weeks compared to a placebo when added to the standard of care.

Market analysts point out that a major flaw in the trial design may have masked…