Moderna Shares Plunge Up to 25% on Apparent Leak of Melanoma Vaccine Data
Unverified social media posts citing a leaked trial report sent Moderna shares tumbling, but the full phase 3 results released later Thursday showed the personalized cancer vaccine, paired with Merck's Keytruda, cut recurrence or death risk by 42%.
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By Principle Post Staff·Published
A smartphone displaying the Moderna logo in front of a blurred Moderna wordmark · Source: Reuters
Moderna shares fell as much as 25% on Thursday after unverified details about the company's closely watched personalized melanoma vaccine began circulating on social media ahead of the data's official release. The selloff was triggered by a post on X from an unverified account citing a report on the trial's results.
The real data looked strong
When the full phase 3 results were released later that day, they appeared to meet or exceed what Wall Street had been expecting. The vaccine, known as intismeran autogene and developed in partnership with Merck, reduced the risk of cancer recurrence or death by 42% in certain melanoma patients when paired with Merck's immunotherapy Keytruda, compared with Keytruda alone. Detailed results were set to be presented at the European Society for Medical Oncology conference over the weekend.
Despite the apparently positive underlying data, the stock swing illustrates how sensitive biotech shares remain to unverified leaks, especially for a closely watched trial that had built up lofty expectations earlier in the year. Merck, a far larger company with a broader drug portfolio, saw its own shares dip only about 1% on the news, reflecting how much more exposed Moderna is to the outcome of a single high-profile trial.
