Immunostaining of PD-L1 in ATLL biopsy samples (n = 135) has further revealed three groups of patients: one group (7.4%) had clear PD-L1 expression in ATLL cells; the second group (58.5%) showed minimal expression of PD-L1 in ATLL cells but abundant expression of PD-L1 in stromal cells; the third group (34.1%) did not express PD-L1 in any cells [216]. This evidence concerns the gene CD274 and adult T-cell leukemia/lymphoma.