Moderna (MRNA) Shares Fall 25% After Cancer Vaccine Data Leak Despite Positive Trial

Moderna (MRNA) shares dropped as much as 25% on Thursday following the leak of partial data on its personalized cancer vaccine, intismeran autogene. The vaccine, developed with Merck, was tested in combination with Merck's immunotherapy Keytruda in a phase 3 trial. The data showed a 42% reduction in the risk of recurrence or death in certain melanoma patients compared with Keytruda alone.

Additionally, the vaccine plus Keytruda reduced the risk of distant cancer spread or death by 38%. About 82% of patients receiving the vaccine and Keytruda were alive without melanoma returning at two years, compared to 70% with only Keytruda. The full trial results were released after the leak and will be presented at the European Society for Medical Oncology conference. Analysts noted the data to be meaningful and clinically positive despite the share price fall, which likely reflects high investor expectations rather than efficacy concerns.

The vaccine is seen as a potential breakthrough and may broaden Moderna's commercial pipeline beyond COVID-19 and flu vaccines. Merck's stock also fell about 1% the same day. Moderna's stock has risen over 530% year-to-date, while Merck's is up nearly 41%. Merck's CEO mentioned efforts to shorten the six-week manufacturing process for the personalized vaccine to increase patient access. This data and upcoming presentations could influence the vaccine's market potential and future studies in other cancers.

This matters for investors because the vaccine's clinical benefits and manufacturing timelines will affect Moderna's future revenue and growth potential in oncology, a new market beyond its existing vaccines.