Moderna shares fall about 25% after skin cancer treatment results leak
Key Facts
Moderna shares fell about 25% during Thursday trading after results leaked from a trial of its experimental skin cancer treatment being developed with Merck, according to BioPharma Dive. Merck shares fell about 1% in the same session, a more muted response to the circulation of study details. The results began circulating through images leaked on social media ahead of the scheduled scientific presentation, prompting the European Society for Medical Oncology to release the study details before its meeting. Myles Minter, an analyst at William Blair, described the stock's move as a "sell-the-news reaction," according to BioPharma Dive's coverage. In separate coverage on the day of the leak, Investing reported that Citi analyst Geoff Meacham maintained his sell rating on Moderna. Meacham set a price target of $80 per share amid persistent concerns about the company's valuation.
Results announced by Merck showed that adding the experimental treatment intismeran autogene to Keytruda reduced the relative risk of melanoma recurrence or death by 42%, compared with Keytruda alone. The trial enrolled 1,137 patients following complete surgical removal of melanoma, the skin cancer targeted by the treatment in this study. The trial compared the group receiving the combination treatment with a group receiving a placebo alongside Keytruda, according to the company. The combination also reduced the relative risk of cancer spreading to distant sites or death by 38%, compared with the control group. Median patient follow-up at the primary analysis was 24.6 months, according to Merck's statement. According to Investing, 82.2% of patients who received the combination treatment were alive and cancer-free after two years, compared with 70% of those who received Keytruda alone.
The release of these details followed a sharp rally in Moderna shares when initial trial results were disclosed in August. The Associated Press, in coverage published by WBUR, reported that the stock more than doubled during the session in which those results were announced. That surge came before details were disclosed on the magnitude of the treatment's benefit for patients. In the earlier mid-stage study, extended follow-up showed that adding intismeran to Keytruda reduced the relative risk of disease recurrence or death by 49%, according to Merck. The same follow-up showed a 59% reduction in the relative risk of distant cancer spread or death, compared with Keytruda alone, in the earlier trial testing the combination treatment approach.
Intismeran involves designing a treatment tailored to each patient, rather than a single formulation for all participants, according to Merck's description of its development process. The treatment is based on the distinctive set of mutations in a patient's tumor to direct the immune response toward the cancer. The company said the aim is to train the immune system to recognize and attack the cancer. In announcing the trial's initial success, Merck and Moderna said "no new safety signals were observed" with the combination treatment. On manufacturing, Moderna disclosed in a filing with the U.S. Securities and Exchange Commission details of its facility in Marlborough, Massachusetts, purpose-built for intismeran. The facility began supplying batches for clinical use in September 2025, according to the filing.
The study continues to assess overall survival, an endpoint whose results Merck said were not yet mature at the primary analysis. The company described the endpoint's status by saying "overall survival data are not yet mature." As the next regulatory step, Merck said in its announcement of the initial success that it would share the study results with regulators for evaluation of the treatment. It also announced plans to present the results at an international medical meeting as part of the trial's scientific disclosure process. Merck plans to hold an oncology-focused investor event during the European Society for Medical Oncology congress on Monday, October 26, 2026.