cDC2 cells sustain mRNA cancer vaccine efficacy without cDC1 in sarcoma-bearing mice

Murphy and Gillanders used conditional knockout mice missing either cDC1 or cDC2 populations, vaccinated them with mRNA encoding tumor neoantigens, then measured CD8 T-cell priming and tumor regression. Both cDC1-deficient and cDC2-deficient cohorts generated functional T-cell responses, but only cDC1-deficient animals fully rejected established sarcomas, indicating cDC2 compensation. The study design comprised 8–12 animals per arm with MHC-tetramer tracking and CRISPR-validated lineage tracing.

This redundancy challenges the long-held view that cDC1 alone drives cross-presentation after mRNA delivery and suggests vaccine lipid nanoparticles can engage multiple dendritic-cell subsets. It also explains why some patients with reduced cDC1 numbers in tumors still respond to mRNA vaccines in ongoing melanoma and lung-cancer trials.

The principal limitation is reliance on transplantable mouse sarcomas; human tumors exhibit greater heterogeneity and immunosuppressive microenvironments. Larger, genetically engineered autochthonous models plus single-cell profiling of human lymph-node samples after mRNA vaccination would strengthen translational relevance.

Future vaccine formulations could deliberately recruit or expand cDC2 populations through targeted adjuvants or chemokine expression, potentially raising response rates in patients with dendritic-cell deficiencies.