MyD88- and CARD11-mutant–specific phenotypes recapitulated in DLBCL patients. (A) PD-L1 (CD274) expression in DLBCL with (MyD88-L265P [L265P]; n = 66) or without (wild-type [WT]; n = 660) a MyD88-L265P mutation (CDKN2A copy number loss cases are excluded, and shown are log₂-transformed and size factor–normalized counts). (B) Frequency of CDKN2A copy number loss in DLBCL with or without the MyD88-L265P mutation (L265P, n = 83; WT, n = 690). (C) MyD88-L265P;CDKN2A-WT DLBCL (n = 66)¹⁴  were grouped based on mean expression of genes compiled from the murine Suvarness signature into 2 cohorts (Suvarness^high cohort is labeled with an asterisk, n = 15). Senescence-impaired MyD88-L265P;CDKN2A-loss DLBCL are shown for comparison (n = 17). (D) GSEA comparing Suvarness^high vs Suvarness^low MyD88-L265P;CDKN2A-WT groups from panel C, using senescence- and immune evasion–associated gene signatures (“SASP,” “E2F target genes,” “Senescence,” “Stemness,” “Negative regulation of immune response,” “Negative regulation of T-cell activation,” and “Positive regulation of cellular response to TGF-β”) and the Eµ-myc–derived MyDness signature (see panel E). Notably, the murine MyDness signature is significantly enriched in the human MyD88-L265P;CDKN2A-WT DLBCL cohort that exhibits a senescence-associated GEP (P < .001, FDR = 0.001). Both Suvarness and MyDness signatures comprise a nonoverlapping set of genes. P ≤ .05 and FDR <0.05 indicate significance. (E) Venn diagram showing overlap of the top 200 genes with highest fold-changes (upregulation; compared with the respective vector control lymphomas) as identified by RNA-seq for all NDM tested in the Eµ-myc mouse model. A mutant-specific unique set of genes was identified for MyD88-L265P- as well as CARD11-L244P-mutant lymphomas, accordingly named MyDness (123 genes) and CARDness (182 unique genes), respectively. (F) Transcriptome-analyzed DLBCL¹⁴  were stratified into 2 groups based on mean expression of genes compiled from the murine MyDness (left) and CARDness signatures (right), respectively, as shown in panel E. Top, GSEA comparing both cohorts (30% of highest vs 30% of lowest signature expressers; n = 231 cases for each group) was performed using gene sets defining senescence-related phenotypes (senescence, SASP, E2F target genes, stemness), T-cell evasion, as well as positive NF-κB and TGF-β responses. P ≤ .05 indicates significance. Bottom, expression levels (log₂-transformed and sf-normalized counts) of PD-L1 (CD274) and PD-L2 (PDCD1LG2), the macrophage chemoattractant Ccl2 and Csf1 as well as the macrophage markers CD68 and Itgam in both cohorts. (G) MyD88-L265P derived MyDness signature identifies a DLBCL subgroup as analyzed in 3 large DLBCL patient cohorts^14-16  that display increased expression of immune-checkpoint inhibitors (blue; CD274, PDCD1LG2), macrophage markers and chemoattractants (green; ITGAM, CD68, CSF-1, CCL2) as well as senescence-associated gene-expression profiles (orange) (see panel F, supplemental Figure 6D, and supplemental Figure 6F-G). Indicated n numbers refer to transcriptomes analyzed. Asterisks indicate significance (P < .05)