In melanoma models lacking COX1/COX2 (Ptgs1−/−Ptgs2−/−), and thus PGE2, MHCIIhiCCR7neg cDC1s retain high levels of IL‐12 and CXCL9, allowing them to cluster with tumor‐specific CD8+ T cells, promoting their activation and driving local immune control. Here, CD8A is linked to neoplasm.