Biology subjects
Publications and source records attributed to Guidetti, F..
Antigen density critically influences CAR T-cell efficacy. We show that ibrutinib induces CD19 upregulation in B-cell lymphoma models, enhancing CAR T-cell cytotoxicity. Pharmacologic modulation of target antigen expression represents a promising strategy to overcome resistance.
Cyclin-dependent kinase 9 (CDK9) drives transcriptional elongation and supports the expression of short-lived oncogenic and anti-apoptotic proteins such as MYC and MCL1. PRT2527 is a potent, selective CDK9 inhibitor currently in early clinical development. We evaluated its preclinical activity in marginal zone lymphoma (MZL) models, including cell lines with acquired resistance to BTK, PI3K, and BCL2 inhibitors. Short exposure (4 hours) to PRT2527 produced nanomolar cytotoxicity across all tested MZL cell lines, with efficacy maintained in resistant derivatives. Transcriptomic profiling of VL51 cells showed broad gene repression, including MYC, IRF4, NF-{kappa}B-related genes, and MCL1, alongside increased expression of HLA class II genes. Moreover, comparison with additional CDK inhibitors revealed a similar transcriptional repression signature, underscoring a conserved CDK-dependent regulatory network. Protein analyses confirmed rapid depletion of MCL1, MYC, RNA polymerase II, and IRF4. Flow cytometry validated increased HLA class II and decreased HLA class I surface expression. Combination studies demonstrated additive to synergistic effects with BTK inhibition (ibrutinib) or dual PI3K/BCL2 inhibition (copanlisib plus venetoclax), independent of baseline drug sensitivity. Mechanistically, these combinations may enhance apoptosis by concurrently suppressing survival signaling and transcriptional addiction. Analysis of patient samples revealed high CDK9 expression, further supporting the biological relevance and therapeutic rationale for targeting CDK9 in this disease. Our findings support the development of CDK9-based combination strategies for relapsed/refractory MZL and other B-cell malignancies, with an additional potential for integration with immunotherapies. Key PointsO_LICDK9 inhibitor PRT2527 kills marginal zone lymphoma cells, regardless of whether they are resistant to other targeted drugs. C_LIO_LIPRT2527 boosts the effects of BTK, PI3K, and BCL2 inhibitors and alters immune-related gene expression. C_LI Draft of graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=141 SRC="FIGDIR/small/705084v1_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@37b9e6org.highwire.dtl.DTLVardef@8de6a5org.highwire.dtl.DTLVardef@219771org.highwire.dtl.DTLVardef@15dabfe_HPS_FORMAT_FIGEXP M_FIG C_FIG
BackgroundAberrant fibroblast growth factor receptor (FGFR) signaling sustains survival and drug tolerance in various cancers, including B-cell lymphomas. We profiled FGFR/FGF expression and evaluated the FGFR1-3 inhibitor infigratinib, both alone and in combination with standard agents, in models of mantle cell lymphoma (MCL), marginal zone lymphoma (MZL), and diffuse large B-cell lymphoma (DLBCL). MethodsTwenty-eight cell lines (MCL n=10; MZL n=7, including BTK/PI3K inhibitor-resistant derivatives; ABC-DLBCL n=3; GCB-DLBCL n=8) were tested by 72-h MTT assays for single-agent and fixed-ratio combination activity. Transcriptome profiling (4, 8, 12 h) was performed in MZL Karpas1718 cells treated with infigratinib (500 nM), ibrutinib (10 nM), or the combination. ResultsMCL preferentially expressed FGFR3/FGF9, whereas ABC-DLBCL and MZL expressed FGFR1/FGF2; FGFR1 was further enriched in resistant MZL models, consistent with autocrine activation. Infigratinib showed dose-dependent but modest single-agent activity across the panel (median IC50 3.58 M, indicating limited efficacy at clinically achievable exposures ([≤]500 nM). However, combinations were broadly synergistic: in MCL, infigratinib with ibrutinib (4/4 lines) and bendamustine (5/5) outperformed either agent alone, with weaker effects with rituximab (2/4). In MZL (parental and resistant), infigratinib synergized with ibrutinib (6/6), copanlisib (6/6), and idelalisib (4/6), restoring sensitivity in resistant derivatives; synergy occurred at infigratinib concentrations [≤]500 nM. Mechanistically, RNA-seq revealed largely distinct single-agent programs: ibrutinib suppressed BCR/NF-{kappa}B/inflammatory signaling, while infigratinib preferentially repressed E2F/MYC cell-cycle modules. In contrast, the combination concomitantly downregulated NF-{kappa}B pathways and abrogated MYC target signatures, with coordinated modulation of apoptosis and DNA-repair transcripts. ConclusionsFGFR1/3-driven autocrine signaling contributes to adaptive survival in MCL and MZL. Although infigratinib has limited single-agent activity, it potentiates BTK/PI3K inhibitors and bendamustine at clinically relevant concentrations and reverses acquired resistance, supporting biomarker-guided clinical evaluation of FGFR blockade in relapsed/refractory MCL and MZL.
BackgroundCXCR4 is a chemokine receptor frequently implicated in the pathogenesis and treatment resistance of B-cell lymphomas and other tumor types. Thus, CXCR4 targeting is explored using various approaches, including small molecules, antibodies, and short peptides. Here, we investigated the antitumor effects of the CXCR4 pharmacological inhibition with the synthetic peptides SPX5551 and balixafortide, as single agents and in combination, in various B-cell lymphoma models. MethodsBinding modalities were assessed via molecular docking and simulation. In vitro assays evaluated single-agent and combinatorial effects of CXCR4 antagonists with BTK, PI3K, and conventional therapies across 20 lymphoma cell lines, including models with acquired resistance. Transcriptomic analyses and mechanistic studies elucidated the pathways modulated by combined CXCR4 and BTK inhibition. ResultsStructural modeling confirmed similar CXCR4 binding modes for SPX5551 and balixafortide. SPX5551 displayed minimal single-agent activity but restored sensitivity to BTK and PI3K inhibitors in resistant marginal zone lymphoma (MZL) models. Across mantle cell lymphoma (MCL), chronic lymphocytic leukemia (CLL), and diffuse large B-cell lymphoma (DLBCL) models, SPX5551 enhanced the efficacy and/or potency of ibrutinib, copanlisib, rituximab, and R-CHOP. In MCL, co-treatment with SPX5551 and ibrutinib synergistically induced apoptosis, inhibited NF-{kappa}B and AKT signaling, and led to broader transcriptomic repression of tumor-promoting pathways compared to either agent alone. ConclusionsAlthough CXCR4 inhibitors alone show limited cytotoxicity, their combination with standard and targeted therapies significantly enhances anti-lymphoma effects, particularly in drug-resistant settings. These findings provide a strong rationale for clinical evaluation of CXCR4 blockade as a combinatorial strategy in B-cell lymphomas.
Introducing Brutons tyrosine kinase (BTK) inhibitors has significantly improved outcomes for patients with B-cell malignancies and autoimmune disorders. However, resistance, either primary or acquired, remains a major clinical challenge. To better understand the underlying resistance mechanisms to BTK inhibitors, we established an ibrutinib-resistant model from a patient-derived splenic marginal zone lymphoma (MZL) cell line (VL51) through prolonged drug exposure. Resistant cells exhibited a 15-fold increase in ibrutinibs IC50, along with distinct morphological changes, mitochondrial activation, and cross-resistance to covalent, non-covalent BTK inhibitors and BTK degraders. Integrated transcriptomic, epigenomic, and proteomic analyses identified overexpression and secretion of IL-16 as a key feature of resistance, driven by chromatin remodeling and activation of the FLI1 transcription factor. IL-16 conferred ibrutinib resistance via CD9-mediated activation of the NF-{kappa}B and AKT signaling pathways and was found to be elevated in the serum of ibrutinib-refractory CLL patients. Functional studies showed that targeting the IL-16/CD9 axis using neutralizing antibodies or CD9-binding peptides restored sensitivity to BTK inhibitors and R-CHOP chemotherapy in MZL, mantle cell lymphoma, and diffuse large B-cell lymphoma models. These findings reveal a novel, targetable resistance mechanism with potential therapeutic implications for overcoming BTK inhibitor resistance in B-cell lymphomas.
Chronic antigenic stimulation is a central factor in the development of marginal zone lymphoma (MZL). While the pharmacological inhibition of the B-cell receptor (BCR) signaling by Brutons tyrosine kinase (BTK) inhibitors is initially effective, the development of resistance remains a challenge in treating MZL and other B-cell malignancies. Enhancer activation remodeling is a key epigenetic mechanism that enables tumor adaptation during therapy. The most active regulatory regions cluster in super-enhancers and produce enhancer RNAs (eRNAs), a class of unstable noncoding transcripts that primarily serve as scaffolds for chromatin looping. However, when stabilized, these eRNAs can evolve into long noncoding RNA (lncRNAs) with distinct functions. To investigate enhancer-associated long non-coding RNAs (elncRNAs) involved in shaping BCR pathway dependence, we conducted a CRISPR interference (CRISPRi) screen in MZL cells. We identified LOC730338, an elncRNA linked to A-to-I RNA editing, which we renamed ADARreg. ADARreg renders tumor cells refractory to BCR pathway inhibition by modulating ADAR2 nuclear translocation and altering RNA modification patterns in key regulatory isoforms through coordinated control of RNA stability and localization, as revealed through subcellular direct RNA sequencing (DRS). In addition, ADARreg induces an immune-suppressive transcriptional program, increasing the production of inhibitory cytokines and receptors that diminish NK cell-mediated cytotoxicity. Together, these findings uncover a novel role for elncRNAs in orchestrating immune evasion and provide a potential therapeutic strategy to overcome resistance in lymphoma and other immune-related diseases. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=116 SRC="FIGDIR/small/627805v2_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@1c3fa92org.highwire.dtl.DTLVardef@177b234org.highwire.dtl.DTLVardef@154a8fdorg.highwire.dtl.DTLVardef@122acfd_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIThe enhancer-associated long non-coding RNA ADARreg modulates RNA editing and alters the stability and localization of key immune-related transcripts, thereby enabling tumor immune evasion. C_LIO_LIADARreg has prognostic and therapeutic relevance, linking resistance mechanisms and immune modulation, which supports the development of RNA-based therapeutic strategies in cancer. C_LI