AstraZeneca (LON: AZN) shares plunged as much as 9% on Wednesday, marking their sharpest one-day decline in years, after the pharmaceutical giant reported disappointing late-stage trial results for its experimental drug Wainua. The setback erased investor optimism surrounding the treatment’s potential in a progressive heart disease and weighed heavily on the FTSE 100 index.
The Phase 3 study found that adding Wainua to the current standard of care failed to significantly reduce the risk of death or major cardiovascular events compared with existing treatment alone. The outcome fell short of market expectations, as many investors had anticipated the drug would achieve its primary endpoint and strengthen AstraZeneca’s cardiovascular pipeline.
The London-listed stock became the biggest drag on the FTSE 100, which slipped about 0.4% in early trading, as investors reassessed the medicine’s commercial outlook.
Morgan Stanley described the trial outcome as a “meaningful downside surprise,” noting that the market had largely expected a successful result despite concerns about the incremental benefit Wainua could offer over established therapies.
The brokerage estimates that consensus forecasts currently include around $3.3 billion in risk-adjusted peak annual sales for Wainua in this heart disease indication. Following the failed trial, analysts expect those revenue projections to be revised significantly lower, which could result in a mid-single-digit percentage reduction in AstraZeneca’s longer-term earnings expectations.
Despite the setback, Morgan Stanley maintained its Overweight rating on AstraZeneca with a 16,500 pence price target. The firm believes investor focus will now shift toward several important late-stage pipeline catalysts expected in the second half of 2026, including lung cancer candidate Dato-DXd, chronic obstructive pulmonary disease treatment tozorakimab, and breast cancer therapy camizestrant.
AstraZeneca and partner Ionis Pharmaceuticals (NASDAQ: IONS) said a full analysis of the Wainua study will be presented at the European Society of Cardiology Congress in August, where additional data may provide further insight into the trial results.


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