CD274 and metastatic melanoma: Higher plasma eNAMPT levels were found in patients with metastatic melanoma than in those with localized stage I-II melanoma or controls (P ≤ 0.0001). In addition, eNAMPT levels correlated positively with LDH levels, a marker of tumor burden, in 39 patients (r = 0.41, P = 0.008). Melanoma patients exhibiting PD-L1+ lesions had significantly increased plasma levels of eNAMPT compared with patients with PD-L1− lesions (P ≤ 0.01).