Scientists at Washington University School of Medicine in St. Louis have discovered that mRNA cancer vaccines work through an immune pathway that researchers did not previously know was involved, a finding that may help explain why some patients with melanoma, lung cancer, or bladder cancer respond exceptionally well to experimental cancer vaccines and others do not.
The study, published April 15, 2026 in Nature, found that even when the immune cell scientists had long believed was essential to mRNA vaccine activation was completely absent, the vaccine still produced strong cancer-killing responses. A related immune cell type — one not previously known to respond to vaccines — stepped in and took over, through a previously unknown mechanism the researchers describe as a "backup" pathway.
