Investigation of PD-L1 Expression in Various Non-Hodgkin's B-cell Lymphomas.

[BACKGROUND & OBJECTIVE] Programmed death ligand-1 (PD-L1) plays a critical role in tumor immune evasion, particularly in Non-Hodgkin's B-cell lymphomas (NHL). This study aimed to evaluate PD-L1 expression across various NHL immunophenotypes and assess its correlation with clinical and demographic parameters.

[METHODS] In this cross-sectional, descriptive-analytical study, 71 formalin-fixed, paraffin-embedded tissue blocks diagnosed with Non-Hodgkin's B-cell lymphoma were retrieved from the pathology archives of Alzahra Hospital and Seyed-al Shohada (Omid) Hospital in Isfahan (2019-2020). PD-L1 expression was assessed immunohistochemically using tumor proportion score (TPS), combined proportion score (CPS), and immune cell (IC) score. Statistical analysis was performed using the Mann-Whitney U and Kruskal-Wallis tests, with p < 0.05 considered statistically significant.

[RESULTS] Among the 71 patients, 67.6% were male, with a mean age of 52.61 ± 18.43 years. Diffuse large B-cell lymphoma (DLBCL) was the most common subtype, accounting for 52.1% of cases. PD-L1 expression was significantly higher in females (TPS: 18.13 ± 9.73; CPS: 28.22 ± 13.31) compared to males (TPS: 4.42 ± 3.56; CPS: 12.08 ± 10.14) (p = 0.040, p = 0.022). No significant differences in PD-L1 expression were observed across age groups. DLBCL demonstrated significantly higher IC and CPS values compared to other subtypes (p < 0.05), while plasmacytoma and Burkitt lymphoma exhibited the lowest scores (e.g., immune score: 1.11 ± 0.11 for plasmacytoma). No statistically significant differences in TPS were noted among the different immunophenotypes (p = 0.119).

[CONCLUSION] Elevated PD-L1 expression, particularly in immune cell scores, suggests potential utility in PD-1/PD-L1-targeted therapies for NHL. However, the prognostic significance of PD-L1 remains inconclusive, highlighting the need for further investigation into its role as a predictive biomarker in the clinical management of Non-Hodgkin's B-cell lymphomas.