A unique expression pattern of LAG3 distinct from that of other immune checkpoints in diffuse large B-cell lymphoma

Although some patients with diffuse large B-cell lymphoma (DLBCL) show a response to immunotherapy, there are still many who do not respond. This suggests that various immune checkpoints are complicatedly intertwined in the composition of the tumor microenvironment of DLBCL.

To comprehensively understand the expression of various immune checkpoint genes in DLBCL, we performed NanoString assay in 98 patients to investigate 579 genes. In addition, we performed immunohistochemistry for LAG-3 and PD-L1 to compare the results with expression in NanoString assay.

As a result of hierarchical clustering of NanoString assay, 98 DLBCLs were classified into three tumor immune microenvironment clusters. Most immune checkpoint genes showed the highest expression in cluster A and the lowest in cluster C. However, the expression of LAG3 was the highest in cluster C and the lowest in cluster A, showing an expression pattern opposite to that of other immune checkpoint genes. In Cluster A, the expression of genes related to T-cell activity such as CD8A and GZMB was increased. In Cluster C, the expression of genes related to major histocompatibility complex molecules was the highest. Immunohistochemical stains showed modest agreement with the NanoString results but did not help clustering.

Our results show that the unique expression pattern of LAG3 in DLBCL contrasts with that of other immune checkpoints. We suggest that the combination of anti-PD-1/PD-L1 and anti-LAG-3 blockades in the immunotherapy of DLBCL patients can have a synergistic effect, improving the immunotherapy efficacy and outcome in DLBCL patients.