Expression of PD-L1 and Its Clinical Significance in MYC/BCL2 Double-expression Large B Cell Lymphoma

Objective To investigate the correlation between MYC/BCL2 double-expression large B cell lymphoma (DEL) and programmed cell death ligand 1 (PD-L1) mRNA or protein expressions and analyze the clinical significance of PD-L1 protein expression in DEL.

Methods We collected 90 cases of diffuse large B-cell lymphoma(DLBCL) and detected MYC and BCL2 protein by immunohistochemical staining, and then grouped them into DEL and non-DEL groups. The expressions of PD-L1 in tumor cells or microenvironment were detected by immunohistochemical double labeling staining. qPCR was used to detect the relative expression of PD-L1 mRNA. The clinicopathological data were collected and followed up.

Results Among 90 cases of DLBCL, there were 28 cases of DEL, 22 cases of PD-L1 expression in tumor cells (PD-L1⁺) and 26 cases in microenvironment (mPD-L1⁺); while, 14 cases of PD-L1 expression in tumor cells and 9 cases in microenvironment in DEL group. PD-L1 protein expression in tumor cells or microenvironment was correlated with DEL (P < 0.05). The relative expression of PD-L1 mRNA was significantly different between two groups (P=0.012). PD-L1⁺ was related to IPI score and B symptom in DEL group (P=0.007, 0.021). PD-L1⁺ and mPD-L1⁺ were correlated with the prognosis of patients in DEL group (P=0.005, 0.001).

Conclusion The mRNA and protein expression of PD-L1 are significantly up-regulated in DEL patients and correlated with the prognosis. PD-L1 could be used as an independent risk factor for the evaluation of poor prognosis of DEL patients.