M1/42 significantly restricted the growth and metastasis of checkpoint inhibitor-resistant pancreatic ductal adenocarcinoma (PDAC) and B16F10 melanoma in the liver and lungs, accompanied by increased tumor infiltration of effector CD8<sup>+</sup> T cells, reduction of T regulatory cells, and a pro-inflammatory cytokine milieu. Here, CD8A is linked to pancreatic ductal adenocarcinoma.