Key facts
- Moderna shares fell 25.2% on Thursday, its steepest one-day percentage fall on record.
- The melanoma vaccine, intismeran, combined with Merck's Keytruda, reduced cancer recurrence or death risk by 42%.
- The treatment cut the risk of distant metastasis or death by 38% compared to Keytruda alone.
- 82.2% of patients receiving the combination remained cancer-free after two years, versus 70% on Keytruda alone.
Moderna shares fell 25.2% on Thursday, its steepest one-day percentage fall on record, erasing approximately $24 billion in market value. The selloff followed the release of late-stage trial data for its personalized melanoma vaccine, intismeran, developed in partnership with Merck. The data showed that the vaccine, when combined with Merck's immunotherapy Keytruda, reduced the risk of cancer recurrence or death by 42% and the risk of distant metastasis or death by 38% compared to Keytruda alone. Analysts described the reaction as a 'sell-the-news' event, noting that high expectations driven by previous company commentary likely contributed to the stock's surge this year. The results are scheduled to be presented on Saturday at the European Society for Medical Oncology meeting in Madrid.