AstraZeneca loses £19bn as Wainua fails key heart disease trial

AstraZeneca shares plunged 9.55%, wiping £19 billion from its market value, after Wainua failed a Phase 3 trial in a form of heart disease.

"Although we are disappointed that the study did not meet the primary endpoint, these results have the potential to guide the treatment approach for ATTR-CM," Brett P. Monia, chief executive officer of Ionis Pharmaceuticals, said.

The CARDIO-TTRansform trial of eplontersen (Wainua) in 1,432 patients with transthyretin-mediated amyloid cardiomyopathy did not show a statistically significant reduction in cardiovascular deaths and recurrent cardiovascular events versus placebo. A prespecified subgroup receiving eplontersen alone showed a nominally significant benefit, with a hazard ratio of 0.71, meaning a 29% lower risk of the composite outcome. No treatment effect was observed in patients already on a stabilizer therapy.

The failure removes one of AstraZeneca's largest late-stage pipeline opportunities. Citi analysts had forecast peak annual sales of more than $6 billion from Wainua and estimated the programme accounted for about 2.8% of the company's valuation.

The trial enrolled participants across 130 sites in 20 countries. Fifty-seven percent of patients in each arm received a stabilizer treatment at baseline, and a further 24% initiated one during the study, reflecting changes in the standard of care for ATTR-CM, according to Ionis. Eplontersen was well tolerated, with a safety profile consistent with prior results. Large and sustained reductions in transthyretin protein were observed, consistent with the silencer drug class.

ATTR-CM is a progressive, fatal disease caused by misfolded transthyretin protein building up in the heart, affecting an estimated 300,000 to 500,000 people worldwide. Eplontersen, a once-monthly RNA-targeted silencer, is already approved for hereditary ATTR polyneuropathy in more than 20 countries, including the EU.

Full results will be presented at the European Society of Cardiology Congress in August 2026. AstraZeneca and Ionis jointly develop and commercialize eplontersen in the US under a global agreement, with AstraZeneca holding exclusive rights outside the US.

The stock was the worst performer on the FTSE 100, which fell 1.7% to 10,489.04, dragged lower by AstraZeneca's decline. Mining stocks including Antofagasta, Anglo American and Glencore rose more than 3%, limiting the index's losses.

The decline puts AstraZeneca shares at their lowest level since early 2026. Investors will watch for analyst rating changes and the ESC Congress presentation in August for further clarity on the drug's prospects in ATTR-CM.

This article is for informational purposes only and does not constitute investment advice.