Las acciones de Moderna y Merck se desploman tras la filtración de datos sobre la vacuna contra el melanoma

Moderna and Merck stock prices have fallen after personalized melanoma cancer vaccine data, eagerly anticipated by the market, fell short of Wall Street's expectations. Moderna's shares dropped 26% on Thursday, a record one-day decline, while Merck's shares fell 3.9%. The leak of the data earlier than expected and later confirmed by Merck.

The vaccine was said to reduce the risk of cancer recurrence by 42% and the risk of distant spread, or metastasis, by 38%. Investors may have expected even greater benefits after the companies announced in August that the personalized vaccine had achieved significant and clinically relevant reductions in recurrence of these deadly tumors.

It was the first final-phase clinical trial with positive results for an RNA-based cancer therapy. Although Moderna's shares surged after that announcement, at the time no details were provided. The results were expected to be presented on Saturday at the European Society of Medical Oncology meeting in Madrid. Analysts have said more information is needed to fully understand the results.

Data showing the therapy's ability to prevent metastasis was "less exceptional" than its benefits in reducing recurrences, TD Cowen analyst Tyler Van Buren wrote in a note to clients before confirming the leak. The first details of the vaccine, known as intismeran autogene, began appearing on unverified sources on the social media platform X on Thursday, causing drops in Moderna and Merck shares.

One of those accounts published a report attributed to Oncology Central describing the results. However, the provided web link was inactive. An earlier study, including a different group of patients over a different period and not allowing direct comparison, concluded that the combination reduced the risk of recurrence or death by 49% and the risk of metastasis by 59%.

Researchers have been trying for many decades to develop cancer vaccines with little success. The results from Merck and Moderna have generated high expectations among oncologists, patients, and investors. This personalized technology has broad potential applications across different types of cancer. Currently, Merck and Moderna are conducting clinical trials on lung cancer, bladder cancer, and other types of tumors.

In the trial, involving over 1,100 patients, the RNA vaccine was used to treat people with a high risk of recurrence after surgically removing melanoma. Patients received the vaccine along with Merck's successful drug Keytruda, and their results were compared to a control group that received only Keytruda.