A personalized mRNA vaccine against melanoma, built on the specific characteristics of each patient’s tumor, has achieved positive results in a phase 3 clinical trial. It was developed by Moderna and Merck, who tested the Intismeran treatment in combination with the immunotherapy Keytruda. The study involved 1,137 high-risk melanoma patients who had already undergone surgery to completely remove the tumor. According to what was communicated by the companies, the therapy achieved both the main objective relating to the reduction of the risk of recurrence and that linked to the spread of the tumor to other parts of the body. The treatment is still experimental and has not been authorized for marketing. However, Moderna and Merck have already started discussions with the regulatory authorities.
How the personalized melanoma vaccine works
Intismeran is not a preventive vaccine like those used against infectious diseases. It is given to people who have already been diagnosed with melanoma. The central point is the personalization of therapy. The individual patient’s tumor is analyzed to identify certain mutations. A specific mRNA vaccine is then produced based on the genetic characteristics detected.
In this way the aim is to provide the immune system with the information necessary to recognize any residual tumor cells and attack them. In the trial, some patients received up to nine doses of the vaccine together with Keytruda, while the comparison group was treated with the immunotherapy alone. The therapy continued for about a year.
Moderna flies to the stock market after the results
The announcement also had a strong impact on the financial markets. Moderna shares gained about 150% during the session, after rising more than 80% in the premarket. The stock reached $163, starting from $62.96 recorded on the eve of the announcement. Merck also benefited from the news, with a share increase of around 11%.
For Moderna, the result represents an important step also on an industrial level. After the strong increase in revenues linked to the Covid vaccine, the company had to face the progressive decline in demand in the following years. The stock had reached an all-time high of $484.47 in August 2021, before falling to $22.28 in November 2025.
How much the melanoma vaccine could be worth
According to estimates by Barclays analysts, the application of the melanoma vaccine alone could generate around $3 billion in annual sales by 2035. For Merck, the treatment could also represent a new source of revenue in view of the future expiration of Keytruda’s patent protection.
The price of the vaccine has not yet been set. Moderna CEO Stéphane Bancel said the companies had only recently received the results and that further evaluations would need to be completed.
However, production presents a difference compared to other personalized oncology therapies: it does not require the direct use of the patient’s cells. According to Moderna, this element could facilitate the increase in production capacity and impact the future cost of treatment.
