Since mesotheliomas are heavily infiltrated by macrophages [7–10] and likely to be infiltrated by MDSCs [33, 34], our finding that CCL2 is elevated in the serum of patients with advanced mesothelioma is consistent with a disease in which the CCL2/CCR2 axis and myeloid-derived cells play an important part. Here, CCR2 is linked to mesothelioma.