Oncogenic Mutations and Tumor Microenvironment Alterations of Older Patients With Diffuse Large B-Cell Lymphoma

Abstract

The incidence of diffuse large B-cell lymphoma (DLBCL) increases by age and older DLBCL are commonly related to poor prognosis. However, the clinical and biological features of older DLBCL patients remain to be determined. A total of 2,445 patients with newly diagnosed DLBCL were enrolled for clinical data analysis according to age at diagnosis, with tumor samples of 1,150 patients assessed by DNA sequencing and 385 patients by RNA sequencing. Older DLBCL presented advanced disease stage, elevated serum lactate dehydrogenase, poor performance status, multiple extranodal involvement, high percentage of double expressor subtype, and adverse clinical outcome. According to molecular features, age was positively correlated with the oncogenic mutations of PIM1, MYD88, BTG2, CD79B, TET2, BTG1, CREBBP, TBL1XR1, and with the MYD88-like genetic subtype. These oncogenic mutations were involved in B-cell receptor/NF-κB signaling, B-cell differentiation, and histone acetylation based on biological functions. Older DLBCL also manifested reduction in CD4⁺ naïve T and CD8⁺ naïve T cells, and also increased recruitment of exhausted T cells and macrophages, leading to immunosuppressive tumor microenvironment. Our work thus contributes to the understanding of aging-related oncogenic mutations and tumor microenvironment alterations in lymphoma progression, and may provide new insights to mechanism-based targeted therapy in DLBCL.

Keywords: B-cell receptor; aging; diffuse large B-cell lymphoma; histone acetylation; oncogenic mutations; tumor microenvironment.

Figure 1

Flow chart of the patient selection and methods. DLBCL, diffuse large B-cell lymphoma; R-CHOP, rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone; WGS, whole genome sequencing; WES, whole exome sequencing.

Figure 2

Relationship between age at diagnosis and clinical outcome upon R-CHOP-based immunochemotherapy. (A, B) Kaplan–Meier models of progression-free survival (A) and overall survival (B) according to age at diagnosis of IPI. (C, D) Kaplan–Meier models of progression-free survival (C) and overall survival (D) according to age at diagnosis of NCCN-IPI. R-CHOP, rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone; IPI, International Prognostic Index; NCCN, National Comprehensive Cancer Network database.

Figure 3

Relationship between oncogenic mutations and age at diagnosis in DLBCL. (A) Oncogenic mutations identified by WGS/WES/targeted sequencing in DLBCL patients. (B) Univariate logistic regression analysis of oncogenic mutations according to age at diagnosis. (C) Univariate logistic regression analysis of MYD88 ^L265P mutations alone or with CD79B mutations according to age at diagnosis. (D) Univariate logistic regression analysis of genetic subtypes according to age at diagnosis. (E) Univariate logistic regression analysis of oncogenic pathways according to age at diagnosis. (F) Correlation between the number of oncogenic mutations sequenced by WGS/WES and age at diagnosis in DLBCL. (B–E) Odd ratios (OR), 95% confidence intervals (95% CI), and P-values are indicated on the left of each forest plot. DLBCL, diffuse large B-cell lymphoma; WGS, whole genome sequencing; WES, whole exome sequencing; AA, Ann Arbor; LDH, lactate dehydrogenase; ECOG, Eastern Cooperative Oncology Group; ENI, extranodal involvement; DE, double expressor; GCB, germinal center B-cell.

Figure 4

Relationship between intratumor immune cells and age at diagnosis in DLBCL. (A) Abundance of immune cell subtypes in patients showing decreased or increased trend with age at diagnosis. (B) Mutation rates of CD79B between exhausted T-high group and exhausted T-low group, and also between macrophage-high group and macrophage-low group. Lower graph indicates P-values. (C) Correlation between the abundance of exhausted T cells and macrophages. P-value and r-value were indicated in the plot. (D) Pathway enrichment analysis in exhausted T-high group (n = 190), as compared to exhausted T-low group (n = 195, P <0.05). Color of points indicates normalized P-value of upregulated pathways in two groups. Size of points indicates number of genes included in each gene set. (E) Correlations between the expression of inhibitory receptors, ligands, and the abundance of exhausted T cells. P-values and r-values were indicated in each plot.

Figure 5

Dysfunctions of macrophages and age at diagnosis in DLBCL. (A) Pathway enrichment analysis in macrophage-high group (n = 192), as compared to macrophages-low group (n = 193, P <0.05). Color of points indicates normalized P-value of upregulated pathways in two groups. Size of points indicates number of genes included in each gene set. (B) Heatmap of genes associated with the markers of macrophage M2 and M1 in macrophage-high group (n = 192), as compared to macrophages-low group (n = 193). (C) Correlations between the expression of inhibitory receptors, ligands, and the abundance of macrophages. P-values and r-values were indicated in each plot. (D) Correlations between the expression of chemokines and the abundance of macrophages. P-values and r-values were indicated in each plot.