Serum CCL22 Increased in Advanced Melanoma Patients with Liver Metastases: Report of 5 Cases

Advanced melanoma patients with liver metastases show a limited response to immunotherapy by the induction of regulatory T cells and depletion of effector cells, which leads to a poor prognosis. Tumor-associated macrophages (TAMs) induce apoptosis of activated antigen-specific CD8+ T cells in melanomas, leading to induction of tolerance to immune checkpoint inhibitors. In addition, TAMs produce various chemokines, and several serum pro-inflammatory chemokines measured at baseline are useful for the prediction of the efficacy of immunomodulatory drugs. In this study, serum levels of CCL22, CXCL5, and CXCL10 were evaluated by ELISA at baseline in 10 melanoma patients, 5 with liver metastases and 5 with lung metastases, treated with anti-PD1 Abs. Serum levels of CCL22, but not CXCL5 and CXCL10, were increased in patients with liver metastases compared to those with lung metastases or historical controls. The present data suggest that elevated serum CCL22 levels might be a biomarker for liver metastases in melanoma patients.