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Moderna shares dropped as much as 25% on Thursday following the leak of partial data on its closely watched cancer vaccine developed with Merck.
The stock fell even though the full data, released later Thursday, appeared positive based on Wall Street expectations ahead of the release. The personalized vaccine, known as intismeran autogene, paired with Merck's immunotherapy Keytruda reduced the risk of recurrence or death in certain melanoma patients by 42% compared to Keytruda alone.
The late-stage trial results were set to be presented at the European Society for Medical Oncology conference this weekend.
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