An experimental vaccine is giving new hope to people with melanoma, one of the most aggressive skin cancers. Merck and Moderna have released Phase 3 trial data showing that a personalized mRNA vaccine, when added to standard immunotherapy, lowered the chance of disease returning or death by 42 percent compared with immunotherapy alone.
Georgina Long, medical director of the Australian Melanoma Institute and lead investigator of the study, called the findings “transformative” and said they could spark a fundamental change in how early‑stage melanoma is treated.
The trial, named INTerpath‑001, enrolled 1,137 patients with high‑risk melanoma who had undergone complete surgical removal of their tumors. Participants were split into two arms: one received only pembrolizumab, a drug that helps the immune system recognize and attack cancer cells, while the other received pembrolizumab together with the mRNA vaccine, Intismeran Autogene.
After an average follow‑up of 24.6 months, the combination therapy reduced the risk of recurrence or death by 42 percent relative to pembrolizumab alone. It also lowered the risk of the cancer spreading to other parts of the body by 38 percent. At the end of the study period, 82.2 percent of patients who received both treatments remained free of recurrence, compared with 70 percent of those who received pembrolizumab only.
Eva Muñoz Couselo, who heads a melanoma research group at the Vall d’Hebron Institute of Oncology in Barcelona and was not involved in the trial, described the results as a major breakthrough for personalized medicine. She noted that this is the first Phase III trial to show that an individualized therapeutic vaccine, designed from the molecular profile of each patient’s tumor, can significantly boost the effectiveness of standard immunotherapy.
The vaccine was created from a tumor sample taken from each participant. Researchers identified specific mutations that produced unique proteins, then selected up to three of these molecular signatures to train the immune system to recognize and attack the cancer cells.
Some participants experienced mild side effects such as fever, fatigue and injection‑site pain, similar to those observed in earlier studies. The Phase 3 data confirmed that the vaccine’s safety profile remains acceptable when combined with pembrolizumab.
“This trial reinforces our belief that mRNA can fundamentally change cancer treatment,” said Stéphane Bancel, CEO of Moderna.
Both companies emphasized that the vaccine is intended to reduce the risk of melanoma returning after prior treatment, not to prevent the disease outright. The therapy still requires further validation and regulatory approval before it can be widely used.
Melanoma survival rates are high when the disease is caught early, yet the cancer still claims more than 50,000 lives worldwide each year. Researchers hope that similar personalized vaccines could eventually be applied to other tumor types. Earlier this year, a separate trial showed that personalized mRNA vaccines markedly improved survival for patients with pancreatic cancer, one of the deadliest malignancies.
“This is a major breakthrough because it suggests we could eventually treat not only melanoma but also other tumors by re‑engaging the immune system,” said Marisol Soengas, a leading melanoma researcher at Spain’s National Cancer Research Center, who was not part of the study.
However, Soengas cautioned that a cure for cancer is not imminent. She highlighted the challenges of scaling up a bespoke vaccine for large patient populations and keeping costs affordable for health‑care systems, noting the logistical complexity of manufacturing a unique product for each individual.