The B cell receptor (BCR) signaling pathway plays a crucial role in B cell development and contributes to the pathogenesis of B cell neoplasms. In B cell malignancies, the BCR is constitutively active through both ligand-dependent and ligand-independent mechanisms, resulting in continuous Bruton tyrosine kinase (BTK) signaling activation, which provides a survival and proliferation advantage to the neoplastic clone. Among B cell malignancies, those in which the most significant results were obtained by treatment with BTK inhibitors (BTKi) include chronic lymphocytic leukemia, mantle cell lymphoma, lymphoplasmacytic lymphoma, and diffuse large B cell lymphoma. Covalent BTKi (namely ibrutinib, acalabrutinib, and zanubrutinib) functions by irreversibly blocking BTK through covalent binding to the cysteine residue 481 (Cys-481) in the ATP-binding domain. Despite the high efficacy and safety of BTKi treatment, a significant fraction of patients affected by B cell malignancies who are treated with these drugs experience disease relapse. Several mechanisms of resistance to covalent BTKi, including Cys-481 mutations of BTK, have been investigated in B cell malignancies. Non-covalent BTKi, such as pirtobrutinib, have been developed and proven effective in patients carrying both Cys-481-mutated and unmutated BTK. Moreover, targeting BTK with proteolysis-targeting chimeras (PROTACs) represents a promising strategy to overcome resistance to BTKi in B cell neoplasms.

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.

Histological transformation (HT) into aggressive lymphoma is a turning point in a significant fraction of patients affected by indolent lymphoproliferative neoplasms, namely, chronic lymphocytic leukemia (CLL), follicular lymphoma (FL), marginal zone lymphomas (MZLs), and lymphoplasmacytic lymphoma (LPL)

Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults. Despite its indolent clinical course, therapy refractoriness and disease progression still represent an unmet clinical need. Before the advent of pathway inhibitors, chemoimmunotherapy (CIT) was the commonest option for CLL treatment and is still widely used in areas with limited access to pathway inhibitors. Several biomarkers of refractoriness to CIT have been highlighted, including the unmutated status of immunoglobulin heavy chain variable genes and genetic lesions of TP53, BIRC3 and NOTCH1. In order to overcome resistance to CIT, targeted pathway inhibitors have become the standard of care for the treatment of CLL, with practice-changing results obtained through the inhibitors of Bruton tyrosine kinase (BTK) and BCL2. However, several acquired genetic lesions causing resistance to covalent and noncovalent BTK inhibitors have been reported, including point mutations of both BTK (e.g., C481S and L528W) and PLCG2 (e.g., R665W). Multiple mechanisms are involved in resistance to the BCL2 inhibitor venetoclax, including point mutations that impair drug binding, the upregulation of BCL2-related anti-apoptotic family members, and microenvironmental alterations. Recently, immune checkpoint inhibitors and CAR-T cells have been tested for CLL treatment, obtaining conflicting results. Potential refractoriness biomarkers to immunotherapy were identified, including abnormal levels of circulating IL-10 and IL-6 and the reduced presence of CD27⁺CD45RO⁻ CD8⁺ T cells.

Circulating tumor DNA (ctDNA) levels can help predict outcomes in diffuse large B-cell lymphoma (DLBCL), but its integration with DLBCL molecular clusters remains unexplored. Using the LymphGen tool in 77 DLBCL cases with both ctDNA and tissue biopsy, a 95.8% concordance rate in molecular cluster assignment was observed, showing the reproducibility of molecular clustering on ctDNA. A multicenter, prospective cohort of 166 patients with newly diagnosed DLBCL was analyzed for ctDNA levels and molecular clusters using cancer personalized profiling by deep sequencing. Patients with ctDNA levels of <2.5 log10 haploid genome equivalents (hGE)/mL had a 4-year progression-free survival (PFS) and overall survival (OS) of 71.7% and 85.7%, respectively, compared with 50.3% and 61.0% for those with higher ctDNA levels (P = .0018 and P = .0017). Recursive partitioning showed that patients with ctDNA levels of ≥2.5 log10 hGE/mL were further stratified by clusters ST2/BN2. In this group, ST2/BN2 patients associated with a favorable outcome with a 4-year PFS and OS of 87.5% and 100%, respectively, compared to 38.0% and 47.1% for other clusters (P = .003 and P = .001). Combining ctDNA levels and ST2/BN2 clusters improved outcome prediction. Low-risk patients (n = 51), characterized by ctDNA levels of <2.5 log10 hGE/mL and/or BN2/ST2 cluster, had a 4-year PFS and OS of 75.3% and 87.8%, respectively. High-risk patients (n = 115), with ctDNA levels of ≥2.5 log10 hGE/mL and no BN2/ST2 cluster, had a 4-year PFS and OS of 38.0% and 47.1%, respectively. Adding cluster assignment to ctDNA levels improved the model’s C statistics (0.63 vs 0.59 for PFS; 0.68 vs 0.63 for OS). Liquid biopsy thus provides a multilayered approach for outcome prediction in DLBCL.