255O Genetic mutations of Tim-3 ligand, and exhausted Tim-3+CD8+ T cells and survival in diffuse large B cell lymphoma

Abstract

Background: Tim-3 is emerging as a promising target for antitumor immunotherapy. A number of clinical trials are ongoing to evaluate anti-Tim-3 therapies as a single agent or combinations in solid tumors and hematologic malignancies. However, there remains a considerable lack of data related to the information of Tim-3 signaling in diffuse large B-cell lymphoma (DLBCL), especially the genetic characteristics and immune microenvironment. Methods: Here, next-generation sequencing was utilized to identify DLBCLs harboring genetic mutations of Tim-3 ligand, and multiple immunofluorescence staining and quantitative pathological analysis techniques were applied to determine the immune microenvironment. Results: Three genetic mutations of galectin-9, which is a major ligand of Tim-3, were identified in six DLBCL patients (6/188, 3.2%). And these mutations had never been reported in DLBCL according to the COSMIC database. We further found that the Tim-3 mRNA level was significantly higher in DLBCL compared to that of normal B cells through the Oncomine database. Using multiplexed immunofluorescence staining, we found that patients with Tim-3 expression on tumor-infiltrating lymphocytes (Tim-3 + TILs) experienced significantly poorer outcomes than those with Tim-3-TILs (p ¼ 0.041), and the median survival times were 65.0 months (95% CI: 71.2e88.6) and 79.9 months (95% CI: 54.4e75.6), respectively. Furthermore, we defined a novel subtype of exhausted T cells, named as exhausted Tim-3 + CD8 + T cells, and also found that patients with exhausted Tim-3 + CD8 + T cells (median survival, 62.8 months, 95% CI: 50.0e75.6) had a significantly shorter survival than those with non-exhausted Tim-3-CD8 + T cells (median survival, 82.5 months, 95% CI: 72.0e92.9) (p ¼ 0.034). Conclusions: Overall, our findings provid an important addition to the genetic information of Tim-3 ligand in DLBCL. And we uncovered that patients with Tim-3 + TILs and exhausted Tim-3 + CD8 + T cells exhibited inferior survival, supporting potential strategies to block Tim-3 alone or in combination with other immune checkpoints as treatment options for DLBCL patients.