Drugmakers Moderna and Merck announced on a Wednesday that a study of an experimental mRNA vaccine for melanoma met its primary objectives. The trial tested the combination of Moderna's personalized vaccine, intismeran, and Merck's immunotherapy drug, Keytruda, in patients who had previously undergone surgery to remove high-risk melanoma. According to the companies, the treatment reduced the risk of the cancer returning or spreading to other organs.
The study targeted a disease that the Skin Cancer Foundation estimates will be diagnosed in more than 234,680 people in the U.S. in 2026. Melanoma is a form of skin cancer that begins in pigment-producing cells called melanocytes and can grow uncontrollably. The goal of the trial was to evaluate adjuvant therapy—treatment given after a primary procedure like surgery—to increase the likelihood of a long-term cure by intervening while the disease is considered most treatable.
Following the announcement, Moderna's stock rose $91.52, or 145%, to reach $154.48 during morning trading. Merck’s shares also increased by $14.35, or 10.6%, to $149.52. Professor Georgina Long, the study's principal investigator from the University of Sydney, stated that the results represent the first time a study has shown this type of treatment can reduce the risk of recurrence or death in melanoma patients. Moderna CEO Stéphane Bancel described the findings as a realization of the long-standing goal to create individualized mRNA cancer treatments.
The scale of the impact is reflected in both the clinical data and the market response. The trial results, which the companies plan to present at an upcoming medical meeting, showed the drug combination kept cancer from returning for longer periods compared to existing treatments. Investors reacted to this potential new market by more than doubling Moderna's share price in a single morning, adding billions to the company's market valuation. This financial shift is significant for Moderna, whose stock had declined from its peak during the COVID-19 vaccine demand in 2021 and 2022.
The success of this trial sets a precedent for the use of mRNA technology beyond infectious diseases and into oncology. By proving that a vaccine can be designed for an individual patient's specific cancer, the drugmakers are attempting to establish what Professor Long called a "new treatment paradigm" for adjuvant therapy. What happens next depends on the formal presentation of the unpublished data to government regulators. While no specific date for a regulatory decision or public availability was reported, the companies have committed to sharing their full findings at an upcoming international medical meeting.