Moderna Shares Surge After Successful Personalized Cancer Vaccine Trial

Moderna Inc. and Merck & Co. announced that their experimental personalized mRNA cancer vaccine, intismeran autogene, successfully met its primary goal in a Phase 3 clinical trial. The study, involving over 1,100 high-risk or advanced melanoma patients, found that the vaccine—administered alongside the immunotherapy drug Keytruda—significantly extended recurrence-free survival and reduced the risk of the disease spreading to distant organs.

Moderna Inc. saw its stock surge approximately 177% on Wednesday, marking the largest one-day gain by any S&P 500 stock this century and adding roughly $44 billion to its market capitalization. The rally caused an estimated $5 billion to $5.5 billion in paper losses for short sellers. While shares declined 24% on Thursday, they rose 6.9% by August 21 as financial institutions including Bank of America and Morgan Stanley raised price targets.

This breakthrough allows the company to diversify its revenue beyond COVID-19 vaccines, which faced plummeting demand and previous funding cuts from the U.S. government. The companies are now testing the personalized approach for bladder, renal cell, and non-small cell lung cancers. Moderna and Merck plan to present the full data at an upcoming international medical meeting and will begin regulatory discussions regarding safety and approval in the coming months.