Investing Reports Moderna Falls More Than 25% Amid Reports of Possible Early Release of Cancer Vaccine Data
Key Facts
Moderna shares fell more than 25% during Thursday's session on 22 October 2026 amid reports of a possible early release of data on the cancer vaccine it is developing with Merck, according to Investing. Merck shares also declined, with the website reporting a drop of more than 3% in the same session. The moves come ahead of the anticipated presentation of results from a study combining the personalized therapy intismeran with Keytruda in melanoma patients following surgery. Merck declined to comment when contacted by the website about the possible early release. The companies had already announced that the combination delivered a statistically significant and clinically meaningful improvement compared with Keytruda alone.
According to Investing's report on figures attributed to the possible early release, 82.2% of patients in the combination therapy group remained alive without their cancer returning after two years. The corresponding figure was 70% among those who received Keytruda alone over the same follow-up period. This comparison concerns recurrence-free survival, one of the measures covered in the companies' initial announcement. That announcement also pointed to improved distant metastasis-free survival when intismeran was added to Keytruda. Merck described the result in its statement as an "improvement in recurrence-free survival and distant metastasis-free survival compared with Keytruda alone." At the time of the initial announcement, the Associated Press reported that the companies had not disclosed how long patients remained free of cancer recurrence or whether they lived longer overall.
The trial, whose initial results were announced in August 2026, included a total of 1,137 patients, according to Merck's statement. It targeted patients with stage IIB to IV melanoma following complete surgical resection, according to the company's description of the study scheduled for presentation in Madrid. Reuters explained that intismeran trains the immune system to attack cancer cells. It does so by targeting mutations specific to each patient's tumor, giving the therapy its personalized nature. In this study, it is used alongside Keytruda, with results compared against a group receiving Keytruda alone. On safety, Merck said in its initial announcement that "no new safety signals were observed" during the trial.
Thursday's decline followed moves in both directions for Moderna shares in recent sessions, according to earlier Investing reports. In morning trading on 16 October 2026, the stock fell 9.2%. It reached a session low of $214.30 at the time, according to the report published that day. The shares then returned to gains on the morning of 19 October 2026, ahead of the anticipated presentation of the vaccine data. They rose 4.4% in that trading to $227.50, according to another report by the website.
The next milestone is the first presentation of the study results at the 2026 European Society for Medical Oncology congress, which Merck announced would take place in Madrid. The congress runs from 23 to 27 October, according to the company's statement on its participation and the study results scheduled for presentation. An earlier Investing report identified 24 October as the date of the presidential session at which the combination therapy data would be presented. The presentation follows the initial announcement of improvements in recurrence-free survival and distant metastasis-free survival compared with Keytruda alone. Meanwhile, Merck said the study was continuing to evaluate other secondary endpoints. These include overall survival, alongside the results the companies have already announced.