Melanoma Trial: mRNA Vaccine Cuts Recurrence and Death Risk

Pharmaceutical partners Merck and Moderna announced Thursday that their personalized mRNA vaccine for melanoma cut the risk of death or recurrence by 42 percent compared to standard treatment in a late-stage trial. The vaccine is designed to target individual tumors, and the companies are already working with regulatory authorities to pursue approval. The study results are scheduled to be presented at the European Society for Medical Oncology conference in Madrid, Spain, but were released ahead of time after an oncology news site reported them early, breaking the embargo.

The trial involved 1,137 patients with stage IIB to IV melanoma whose tumors had been surgically removed before enrollment. Patients were assigned randomly, with two receiving one arm of the study for every one receiving the other. One group received the personalized mRNA vaccine alongside standard treatment, while the other received standard treatment alone. The standard treatment was Merck's monoclonal antibody therapy Keytruda. The full data set has been accepted for publication in the New England Journal of Medicine.

The vaccine's success could signal a broader shift in how cancer therapies are developed. mRNA vaccines, which became widely known through COVID-19 shots, work by teaching the immune system to recognize specific targets, and in this case the targets are tailored to each patient's own tumor. The trial results were initially reported in August, when the companies confirmed the vaccine had met its goals but withheld detailed figures pending the oncology conference.

Moderna CEO Stéphane Bancel said the technology was built on a belief that mRNA could create cancer treatments matched to each patient's tumor. The trial results, he said in a statement, "mark a defining moment for that vision and show what's possible when we rethink how medicines are made." He added that the data "reinforce our conviction that mRNA has the potential to fundamentally change how we treat cancer."

The next step involves regulatory submissions, as the companies work toward bringing the vaccine to patients. The full trial data is set to be published in the New England Journal of Medicine. If approved, the vaccine would represent a new category of individualized cancer treatment, one tailored to the genetic makeup of each patient's tumor rather than applied as a uniform approach across all patients.