CXCL16 and neoplasm: CXCR6 was initially identified as an HIV co-receptor and is widely present on multiple immune cell types, such as memory T cells, natural killer (NK) cells, NKT cells, dendritic cells, alveolar macrophages, and innate lymphoid cells.42 Its specific ligand, CXCL16, occurs in both membrane-bound and secreted isoforms.42 Earlier work has highlighted the importance of the CXCL16/CXCR6 pathway in influencing tumor proliferation, migration, and invasiveness.43,44 However, CXCR6 expression on T cells in the tumor microenvironment may serve distinct functional roles.