AstraZeneca and Ionis shares fall after Wainua misses heart-disease trial endpoint

AstraZeneca and Ionis Pharmaceuticals shares fell after their partnered drug Wainua missed the main goal of a late-stage trial in transthyretin-mediated amyloid cardiomyopathy, a setback that weakens the case for expanding the medicine into a larger heart-disease market.

The companies said Wainua, also known as eplontersen, did not deliver a statistically significant benefit in the Phase 3 CARDIO-TTRansform study. The trial was designed to test whether the drug could help patients with transthyretin-mediated amyloid cardiomyopathy, a rare and serious condition in which amyloid protein builds up in the heart.

AstraZeneca said the result adds to scientific understanding of the disease and of treatment approaches, but the readout still lands as a commercial and strategic disappointment. Wainua already has approval in more than 20 countries for hereditary transthyretin amyloidosis with polyneuropathy, so the miss does not erase the drug’s existing market, but it does undercut hopes for a broader cardiomyopathy label.

Trial readout

The companies did not say the study achieved its primary endpoint. Coverage of the readout said the trial did not significantly reduce cardiovascular-related deaths or recurrent cardiovascular events versus standard care.

Media reports also said CARDIO-TTRansform enrolled 1,432 patients across 20 countries and followed them for about 140 weeks. That scale made the program one of the more important expansion bets for Wainua.

The miss is particularly relevant because the drug had been viewed as a potential growth driver for AstraZeneca’s cardiovascular, renal and metabolism business. For Ionis, which co-develops the therapy, the result trims the value of a key partnered asset and may reduce near-term expectations for a cardiomyopathy filing.

Market reaction

Investors responded quickly. AstraZeneca shares fell as much as 13% intraday before closing down 6.2% in London, a move that market reports said wiped about £13 billion from the company’s market value.

Ionis also fell sharply in U.S. trading. Depending on when the session was measured, reports put the decline at roughly 17% to 24%.

That reaction reflects more than one failed study. It also captures the market’s concern that a positive cardiomyopathy readout could have strengthened AstraZeneca’s growth narrative and opened a more valuable expansion path for Wainua.

What comes next

AstraZeneca and Ionis said they will analyze the full data set and present the findings at the European Society of Cardiology Congress in August.

That presentation may help clarify whether any subgroup signals matter scientifically or commercially, but the core message from the initial readout is negative. The companies have not said whether they will pursue a cardiomyopathy filing after the miss.

For now, the drug remains approved for hereditary transthyretin amyloidosis with polyneuropathy, but the failed heart-disease study has made a broader commercial rollout much harder to justify.