Patients with non-germinal-center B-cell-like (non-GCB) diffuse large B-cell lymphoma (DLBCL) and programmed death ligand (PD-L1) expression are approximately 17% less likely to survive after 5 years than those without PD-L1 expression.
A group of Chinese researchers led by Li-Yang Hu, State Key Laboratory of Oncology, conducted a study to detect the expression of PD-L1 in DLBCL and to analyze its relationship with prognosis. Researchers reviewed the medical records of 204 patients newly diagnosed with DLBCL in a single medical center from 2005 through 2012. Using immunohistochemistry, PD-L1 expression in tumor tissue samples were evaluated, with a threshold for positivity defined as at least 5% of lymphoma cells with PD-L1 expression in tumor cells and at least 20% of malignant and non-malignant cells with PD-L1 expression in the tumor microenvironment.
“Immunotherapy targeting the PD-1/PD-L1 pathway may benefit patients with DLBCL, particularly those with non–GCB subtype DLBCL, which might benefit from blockade of the PD-1/PD-L1 immune checkpoint,” wrote Li-Yang Hu in the study, which was published in the Chinese Journal of Cancer (online December 16, 2017; doi:10.1186/s40880-017-0262-z).
Researchers noted that 49% of patients had tumor cells positive for PD-L1, with 21.6% PD-L1 positivity in the tumor microenvironment. PD-L1 positivity was more common in tumor cells (P = .02) and the tumor microenvironment (P = .04) for patients with non-GCB subtype compared with patients with GCB subtype, and PD-L1 expression in the tumor microenvironment was associated with resistance to first-line chemotherapy (P = .03).
As for the prognostic implications of PD-L1 positivity in non-GCB DLBCL, researchers reported 5-year overall survival (OS) rates of 50% and 67.3% in patients with and without PD-L1 expression in tumor cells, respectively (P = .02). Additionally, the 5-year progression-free survival (PFS) rates were 39.6% and 59.6% in patients with and without PD-L1 expression in the tumor microenvironment, respectively.
Results of the study led researchers to conclude that PD-L1 positivity is a prognostic indicator of shorter survival in patients with non-GCB DLBCL. “For patients with PD-L1 expression, more strategies such as anti-PD-L1 antibody treatment should be recommended,” they wrote.—Zachary Bessette