Pre-metastatic cancer exosomes induce immune surveillance by patrolling monocytes at the metastatic niche

Metastatic cancers produce exosomes that condition pre-metastatic niches in remote microenvironments to favor metastasis. In contrast, here we show that exosomes from poorly metastatic melanoma cells can potently inhibit metastasis to the lung. These “non-metastatic” exosomes stimulate an innate immune response through the expansion of Ly6C low patrolling monocytes (PMo) in the bone marrow, which then cause cancer cell clearance at the...