CD274 and metastatic melanoma: However, more recently, studies have shown that expression of PD-L1 metastatic melanoma correlates with the presence of tumor-infiltrating lymphocytes (TILs) in human melanocytic lesions, such that 98% of PD-L1(+) tumors were associated with TILs compared with only 28% of PD-L1(−) tumors.