Epigenetic regulation is critical to B cell development, guiding gene expression via DNA methylation, histone modifications, chromatin remodeling, and noncoding RNAs. In mature B cell neoplasms, particularly diffuse large B cell lymphoma (DLBCL), follicular lymphoma (FL), and chronic lymphocytic leukemia (CLL), these mechanisms are frequently disrupted. Recurrent mutations in key epigenetic regulators such as EZH2, KMT2D, CREBBP, and TET2 lead to altered chromatin states, repression of tumor suppressor genes, and enhanced oncogenic signaling. Dysregulation of specific microRNAs (e.g., miR-155, miR-21) further contributes to pathogenesis and therapeutic resistance. In DLBCL, hypermethylation of SMAD1 and CREBBP mutations are associated with immune evasion and chemoresistance. In FL, EZH2 gain-of-function and KMT2D loss-of-function mutations alter germinal center B cell programming, while in CLL, DNA hypomethylation patterns reflect the cell of origin and correlate with clinical outcome. Targeted therapies such as the EZH2 inhibitor tazemetostat have demonstrated efficacy in EZH2-mutant FL, while HDAC and BET inhibitors show variable responses across B cell malignancies. The limitations of current epigenetic therapies reflect the complexity of targeting epigenetic dysregulation rather than therapeutic futility. These challenges nonetheless highlight the relevance of epigenetic alterations as biomarkers and therapeutic targets, with potential to improve the management of mature B cell neoplasms.

Early identification of relapsing/refractory diffuse large B-cell lymphoma (DLBCL) represents an unmet clinical need. A real-life cohort of newly diagnosed DLBCL (n = 120) treated with R-CHOP was investigated. Using the standardized uptake value (SUV) threshold of 4.0, PET/CT radiomics variables (SUVmax, tMTV, tTLG and Dmax) were collected. Circulating tumor DNA (ctDNA) analysis by CAPP-seq yielded baseline ctDNA levels and LymphGen molecular clustering. The best cut-off for both PET/CT parameters and ctDNA levels were identified by max-stat statistics. tMTV, tTLG and Dmax retained independent prognostic value when adjusted for ctDNA levels and were grouped together in a variable named high-risk PET. By multivariate analysis, ctDNA-high and high-risk PET independently predicted PFS and were combined into a 2-factor prognostic model (C-indices: 0.712 for PFS and 0.696 for OS). Molecular clustering, by capturing high-risk biological features of DLBCL, further improved outcome prediction. Consistently, BN2/EZB/ST2 clusters maintained an independent association with better PFS when adjusted for the 2-factor model variables and were therefore included in a 3-factor prognostic score (C-indices: 0.745 for PFS and 0.746 for OS), that identified a very high-risk group of patients (n = 22, 40-month PFS 12.1%) which should be prioritized for early response evaluation and for access to novel agents.

The mutational status of immunoglobulin (IG) light chain genes in chronic lymphocytic leukemia (CLL) and its clinical impact have not been extensively studied. To assess their prognostic significance, the IG light chain gene repertoire in CLL patients has been evaluated using a training-validation approach. In the training cohort (N = 573 CLL), 92.5% showed productive IG light chain genes rearrangements, with IGKV4-1 (20.5%) and IGLV3-21 (19.0%) being the most common. A 99.0% somatic hypermutation cut-off was identified as the best predictor for time to first treatment (TTFT) in 414 Binet A CLL patients of the training cohort. Patients with unmutated (UM) light chain genes displayed a 10-year treatment free probability of 32.4% versus 73.2% for those with mutated (M) genes (p < 0.0001). Importantly, UM light chain genes maintained an independent association with a shorter TTFT when adjusted for the IPS-E prognostic model variables, that also includes IGHV mutational status. The validation cohort of 343 Rai 0 patients confirmed these findings, with UM light chain genes predicting a 7-year treatment free probability of 42.0% versus 73.7% for M genes (p < 0.0001). These results indicate that the mutational status of the light chain genes is an independent predictor of shorter TTFT in early-stage CLL patients.

Despite the development of robust prognostic biomarkers for risk stratification in newly diagnosed diffuse large B-cell lymphoma (DLBCL), namely international prognostic index (IPI), cell-of-origin (COO), circulating tumor DNA (ctDNA) and molecular clusters, none of these capture potential host-related features. In this study, untargeted plasma metabolomics was performed in a discovery cohort of 96 newly diagnosed R-CHOP-treated DLBCL patients. The key finding was validated in an independent cohort of 42 DLBCL with comparable clinical characteristics and outcomes. None of the 280 identified plasma metabolites was associated with COO classification subtypes. Conversely, the metabolomic profile appeared to show variations across ctDNA-defined molecular clusters. After an elastic net regression-based survival analysis, 2-hydroxybutyric acid (2HB) was selected as the only endogenous metabolite to be associated with worse progression-free survival (PFS) in the discovery cohort. The impact of 2HB levels on PFS was confirmed in the validation cohort. Also, 2HB levels (HR 2.09, 95% CI 1.04-4.19, p=0.04) maintained an independent association with shorter PFS when adjusted for higher ctDNA levels (HR 2.08, 95% CI 1.06-4.08, p=0.03). Therefore, 2HB and ctDNA levels were included in a two-factor prognostic score based entirely on minimally invasive plasma-derived biomarkers. This hypothesis-generating score improved outcome prediction compared with ctDNA assessment alone and enabled the identification of high-risk patients who might benefit from early restaging and potential treatment intensification (24-month PFS 28.8%). In conclusion, plasma metabolomics revealed a prognostically relevant role and 2HB sorted out as a potential host-related biomarker able to refine risk stratification in newly diagnosed DLBCL.