Moderna shares plunge after leak of partial cancer vaccine data despite positive results

Moderna shares plunged more than 25% on Thursday, while Merck shares fell over 3%, following what appeared to be an early leak of clinical trial results for an experimental cancer vaccine. According to Investing.com, the data appeared on the medical news website Oncology Central around 12:30 p.m. ET before being removed. The results were scheduled for presentation at the ESMO Congress this Saturday.

The leaked report indicated that combining the personalized mRNA cancer vaccine, known as intismeran autogene, with Merck's immunotherapy Keytruda reduced the risk of melanoma returning or death by 42% compared to using Keytruda alone. Investing.com reports that in the Phase 3 trial involving 1,137 patients, 82.2% of those receiving the combination remained alive and cancer-free after two years, compared to 70% of those receiving Keytruda alone.

While the companies previously announced in August that the trial met its main goals, they had not yet disclosed these detailed results.

CNBC noted that Moderna's stock fell despite the full data, released later Thursday, appearing positive based on Wall Street expectations ahead of the release.

Brief written by urgent.news from CNBC, Investing.com — 2 reports on this story. Machine-written — may contain errors; check the original before relying on it.