An experimental vaccine offers new hope to patients with melanoma, one of the most aggressive forms of skin cancer. The pharmaceutical companies Merck and Moderna released the results of a Phase 3 clinical trial that evaluated the efficacy of a personalized mRNA-based vaccine that, when combined with immunotherapy, reduced the risk of disease recurrence or death by 42 percent compared to treatment with the immunotherapy drug alone.

Georgina Long, medical director of the Australian Melanoma Institute and the study’s principal investigator, said in a statement that these results are “transformative” and “have the potential to make a foundational shift in how we treat patients with earlier-stage melanoma.”

The trial, known as INTerpath-001, included 1,137 people with high-risk melanoma who had undergone surgery to completely remove their tumors. The participants were divided into two groups. Those in the first group received only Pembrolizumab, a drug that helps the immune system detect and fight cancer cells, while those in the second group were treated with the same drug in combination with the mRNA vaccine, called Intismeran Autogene.

After monitoring the participants for an average of 24.6 months, the researchers determined that addition of the vaccine reduced the risk of cancer recurrence or death by 42 percent compared to Pembrolizumab alone.

The results also showed that the experimental treatment reduced the risk of the disease spreading to other parts of the body by 38 percent. At the end of the follow-up period, 82.2 percent of patients who received both treatments remained recurrence-free, compared with 70 percent of those who received Pembrolizumab alone.

“The results of the INTerpath-001 study represent a major breakthrough in the treatment of melanoma and, in particular, in the development of personalized medicine,” Eva Muñoz Couselo—who leads a melanoma research group at the Vall d’Hebron Institute of Oncology, in Barcelona and who was not involved in the study—told SMC Spain. “For the first time, a Phase III trial has demonstrated that an individualized therapeutic vaccine, designed on the basis of the molecular characteristics of each patient’s tumor, can significantly improve the outcomes of conventional immunotherapy.”

The laboratories explained that the vaccine was developed from a tumor sample taken from each patient, which was used to identify specific mutations that would create distinct proteins the immune system could learn to recognize in order to attack cancer cells. The scientists selected up to three of these molecular signatures per patient.