Moderna and Merck treatment cuts risk of melanoma recurrence or death by 42% in Phase III
Key Facts
The personalized experimental messenger RNA-based treatment intismeran, when given with Keytruda, reduced the risk of melanoma recurrence or death by 42% compared with placebo plus Keytruda, according to Phase III results from the INTerpath-001 trial published by Moderna and Merck. The finding was based on a prespecified primary analysis, recording a hazard ratio of 0.58, with a 95% confidence interval between 0.45 and 0.75, and a p-value below 0.001. In another result, the risk of distant cancer spread or death fell by 38% compared with the comparator treatment. The trial included more than 1,100 patients, placing the figures within a large-scale late-stage study. Intismeran remains an experimental treatment given after surgical resection, not an approved therapy.
The study targeted patients with stage IIB to IV cutaneous melanoma after complete tumor resection. Participants in the treatment arm received intismeran at a dose of 1 mg every three weeks, for up to 9 doses, alongside Keytruda. The comparator group received placebo with Keytruda, allowing researchers to measure the added benefit of the experimental treatment to the immunotherapy used in the trial. The companies described the reduction in the risk of recurrence or death as the result of the prespecified primary analysis. This relative risk reduction differs from the recurrence-free survival rate at a specific time point; the reported result here compares risk between the treatment groups during the trial follow-up.
The treatment’s personalized nature requires steps before a dose is given: the process begins with analysis of the tumor’s genes, followed by preparation of a patient-specific vaccine prescription. The Associated Press said this process can take about six weeks or more for each patient. Manufacturing the dose after the prescription is prepared takes a few days, according to the agency. This makes the timing of analysis and customization part of the treatment process, alongside a regimen of up to 9 doses. The trial is intended to use the vaccine after surgery, in the context of reducing the likelihood of the disease returning or spreading.
On safety, treatment-related adverse events of grade 3 to 5 occurred in 14.2% of patients in the intismeran and Keytruda group, compared with 13.4% in the comparator group. The companies said they had observed no new safety signals. Overall survival data are not yet mature, although the companies pointed to a favorable trend in the available results. The trial continues to follow patients to assess overall survival and other endpoints. The reported recurrence and spread results therefore remain separate from a final judgment on overall survival.
The detailed data were published after they were leaked on a specialist oncology website earlier on Thursday, according to Reuters. The INTerpath-001 results were scheduled to be presented at the European Society for Medical Oncology conference in Madrid, at a meeting running from October 23 to 27, 2026. After the leak, the results were released early, while the presentation remained scheduled as planned. In August, Moderna and Merck had announced that the trial was successful without publishing detailed figures, and the stock rose from that announcement until it had nearly quadrupled from its level at Wednesday’s close. A UBS analyst called the recurrence-free survival results “strong data” and described the decline as an expected “sell the news” reaction.
Moderna shares fell 17.57% in Thursday’s session, October 22, closing at $202.63, compared with $245.81 in the previous session, according to EL7 data. The Associated Press described the decline as 18% when rounded, noting that the stock remained more than 200% above its level in late August. A Reuters report linked the drop to a “sell the news” reaction after the results leaked, while an analyst at William Blair described the trial data as “fantastic” and agreed that the reversal appeared to be that type of reaction. The same analyst noted that investors may wonder whether the treatment will deliver the same efficacy in other types of cancer to justify the high valuation. On the regulatory path, Moderna and Merck said they were in discussions with relevant authorities about the next steps toward an approval application, without announcing a filing date.