Moderna and Merck Report Vaccine Cuts Melanoma Recurrence Risk by 42 Percent
A late-stage trial showed personalized mRNA vaccines paired with standard therapy lowered the chance of death or the disease returning in melanoma patients.
By Tyler Khalil ·
Patients with advanced melanoma who received a personalized mRNA vaccine alongside standard care saw a 42 percent lower risk of death or the cancer coming back, compared with those who received standard therapy alone, according to results announced Thursday by Moderna and Merck. The companies said they are now engaging with regulatory authorities regarding approval of the vaccine.
The trial enrolled 1,137 patients with stage IIB to stage IV melanoma whose tumors had already been removed by surgery. Participants were assigned in a 2-to-1 ratio to receive either the personalized vaccine combined with standard treatment or standard treatment alone. The standard therapy used was Merck's monoclonal antibody cancer treatment Keytruda.
The data stems from a Phase 3 trial, and the full dataset has been accepted for publication in the New England Journal of Medicine. The companies had signaled in August that the trial met its goals but withheld specifics pending presentation at a scientific conference. That event, the European Society for Medical Oncology meeting in Madrid, Spain, was set to include presentation of the results Saturday. However, after an oncology news site reported the findings ahead of schedule, the companies released the top-line results early.
Moderna CEO Stéphane Bancel said the findings reflect the company's early belief in the technology. "From the beginning, we believed mRNA technology could make it possible to develop cancer treatments uniquely matched to each patient's tumor," he said in a statement. He added that the results "mark a defining moment for that vision and show what's possible when we rethink how medicines are made." Bancel also said the data "reinforce our conviction that mRNA has the potential to fundamentally change how we treat cancer."
Melanoma is the deadliest form of skin cancer, and the companies have characterized the trial results as a significant advance in treating the disease. The announcement also touches on broader hopes in the field that mRNA vaccines and individualized cancer-targeting medicines could represent a new direction for cancer therapies.
As of October 22, 2026, the vaccine has not been approved for use. The companies are in discussions with regulators regarding that process, and no timeline for a decision has been provided. Details on safety outcomes and other secondary endpoints were not included in the announcement, and the full dataset has not yet been published.
The trial's design also means the results reflect outcomes for patients who had surgery to remove tumors before entering the study. Questions remain about how the vaccine performs in other settings, and about long-term follow-up beyond the period covered by this analysis.
The findings could carry significance for patients and providers in the Pacific Northwest, where skin cancer rates have been a concern due to sun exposure. Any approval would still require regulatory review, and the data underlying the reported figures has not been released in full.
Moderna and Merck are partners on the vaccine. The companies did not disclose any pricing or availability information in Thursday's statement.
