Purpose: We aimed to evaluate the expression level of programmed death ligand-1 (PD-L1) and its effects on prognosis in acute myeloid leukemia. Methods: The flow cytometry was used to detect PD-L1 expression on leukemic cells of 86 de novo acute myeloid leukemia patients with longitudinal follow-up. Results: Median follow-up was 13 (0–73) months. The mean of expression level was 3.22 ± 0.47 at diagnosis and ranged from 0 to 28%. PD-L1 expression tended to be lower in patients with acute promyelocytic leukemia (2.47 ± 1.08, p = 0.09) but there was no significant difference between neither diagnostic nor cytogenetic subgroups. There was no difference in PD-L1 levels between the patients who achieved complete remission (3.4 ± 0.61) and those who did not (2.91 ± 0.72, p = 0.94). The patients with low PD-L1 at diagnosis (median 25 mo [95% CI; 0–56.7]) had a longer overall survival compared with high PD-L1 (median 13 mo [95% CI; 5.52–25.17], p = 0.079). PD-L1 expression was lower at relapse (2.04 ± 0.79) compared to initial diagnosis (4.52 ± 0.93, p = 0.049). The patients who had overall survival longer than 1 year showed lower PD-L1 expression at relapse (0.66 ± 0.93) compared with who had not (5.06 ± 4.28, p = 0.052). A negative correlation between CD33 and PD-L1 (r = − 0.303, p = 0.005) was detected. Conclusion: Despite its low expression levels, PD-L1 appears to be a clinically important prognostic factor. The negative correlation determined between PD-L1 and CD33 supports the combination approach of PD-L1 inhibitors and CD33 targeted immunotherapies.

目的：我们旨在评估程序性死亡配体-1（PD-L1）的表达水平及其对急性髓系白血病预后的影响。方法：采用流式细胞仪检测纵向随访的86例新发急性髓系白血病患者白血病细胞上PD-L1的表达情况。结果：中位随访时间为 13 (0–73) 个月。诊断时表达水平平均值为 3.22 ± 0.47，范围为 0 至 28%。急性早幼粒细胞白血病患者的 PD-L1 表达往往较低（2.47 ± 1.08，p  = 0.09），但诊断亚组和细胞遗传学亚组之间没有显着差异。达到完全缓解的患者 (3.4 ± 0.61) 和未达到完全缓解的患者 (2.91 ± 0.72， p)之间的 PD-L1 水平没有差异。 = 0.94）。与高 PD-L1（中位 13 个月 [95% CI；5.52-25.17]）相比，诊断时 PD-L1 低的患者（中位 25 个月 [95% CI；0–56.7]）的总生存期更长，p  = 0.079）。与初次诊断时 (4.52 ± 0.93， p  = 0.049)相比，复发时 PD-L1 表达较低 (2.04 ± 0.79)。总生存期超过 1 年的患者在复发时表现出较低的 PD-L1 表达 (0.66 ± 0.93) 与未达到总生存期的患者 (5.06 ± 4.28, p  =  0.052 ) 相比。CD33 和 PD-L1 之间呈负相关 (r = − 0.303, p = 0.005) 被检测到。结论：尽管 PD-L1 表达水平较低，但它似乎是临床上重要的预后因素。PD-L1 和 CD33 之间确定的负相关性支持 PD-L1 抑制剂和 CD33 靶向免疫疗法的组合方法。