Chronic Lymphocytic Leukemia Cells Research Articles

Somatic Recombination Between an Ancient and a Recent NOTCH2 Gene Variant Is Associated with the NOTCH2 Gain-of-Function Phenotype in Chronic Lymphocytic Leukemia

Constitutively active NOTCH2 signaling is a hallmark in chronic lymphocytic leukemia (CLL). The precise underlying defect remains obscure. Here we show that the mRNA sequence coding for the NOTCH2 negative regulatory region (NRR) is consistently deleted in CLL cells. The most common NOTCH2ΔNRR-DEL2 deletion is associated with two intronic single nucleotide variations (SNVs) which either create (CTTAT, G>A for rs2453058) or destroy (CTCGT, A>G for rs5025718) a putative splicing branch point sequence (BPS). Phylogenetic analysis demonstrates that rs2453058 is part of an ancient NOTCH2 gene variant (*1A01) which is associated with type 2 diabetes mellitus (T2DM) and is two times more frequent in Europeans than in East Asians, resembling the differences in CLL incidence. In contrast, rs5025718 belongs to a recent NOTCH2 variant (*1a4) that dominates the world outside Africa. Nanopore sequencing indicates that somatic reciprocal crossing over between rs2453058 (*1A01) and rs5025718 (*1a4) leads to recombined NOTCH2 alleles with altered BPS patterns in NOTCH2*1A01/*1a4 CLL cases. This would explain the loss of the NRR domain by aberrant pre-mRNA splicing and consequently the NOTCH2 gain-of-function phenotype. Together, our findings suggest that somatic recombination of inherited NOTCH2 variants might be relevant to CLL etiology and may at least partly explain its geographical clustering.

CD74 promotes the formation of an immunosuppressive tumor microenvironment in triple-negative breast cancer in mice by inducing the expansion of tolerogenic dendritic cells and regulatory B cells.

CD74 is a cell-surface receptor for the cytokine macrophage migration inhibitory factor (MIF). MIF binding to CD74 induces a signaling cascade resulting in the release of its cytosolic intracellular domain (CD74-ICD), which regulates transcription in naïve B and chronic lymphocytic leukemia (CLL) cells. In the current study, we investigated the role of CD74 in the regulation of the immunosuppressive tumor microenvironment (TME) in triple-negative breast cancer (TNBC). TNBC is the most aggressive breast cancer subtype and is characterized by massive infiltration of immune cells to the tumor microenvironment, making this tumor a good candidate for immunotherapy. The tumor and immune cells in TNBC express high levels of CD74; however, the function of this receptor in the tumor environment has not been extensively characterized. Regulatory B cells (Bregs) and tolerogenic dendritic cells) tol-DCs (were previously shown to attenuate the antitumor immune response in TNBC. Here, we demonstrate that CD74 enhances tumor growth by inducing the expansion of tumor-infiltrating tol-DCs and Bregs. Utilizing CD74-KO mice, Cre-flox mice lacking CD74 in CD23+ mature B cells, mice lacking CD74 in the CD11c+ population, and a CD74 inhibitor (DRQ), we elucidate the mechanism by which CD74 inhibits antitumor immunity. MIF secreted from the tumor cells activates CD74 expressed on DCs. This activation induces the binding of CD74-ICD to the SP1 promotor, resulting in the up-regulation of SP1 expression. SP1 binds the IL-1β promotor, leading to the down-regulation of its transcription. The reduced levels of IL-1β lead to decreased antitumor activity by allowing expansion of the tol-DC, which induces the expansion of the Breg population, supporting the cross-talk between these 2 populations. Taken together, these results suggest that CD74+ CD11c+ DCs are the dominant cell type involved in the regulation of TNBC progression. These findings indicate that CD74 might serve as a novel therapeutic target in TNBC.

A case of chronic lymphocytic leukemia with a paraneoplastic neurologic syndrome and leptomeningeal disease

Abstract Purpose Chronic lymphocytic leukemia (CLL) is a hematologic malignancy characterized by overproduction of monoclonal B cells. Paraneoplastic neurologic syndrome (PNS) and leptomeningeal disease (LMD) associated with CLL are both rare entities. We present a unique case that is, to our knowledge, the second reported case of CLL associated with Kelch-like protein 11– (KLHL11-) PNS and the first case of CLL with both LMD and KLHL11-PNS. Methods/results The patient was a 68-year-old woman who developed abdominal pain, nausea, vomiting, and vertigo. Imaging revealed retroperitoneal lymphadenopathy. After further studies, including flow cytometry, she was diagnosed with CLL. She received one dose of pembrolizumab with ibrutinib, and months later received three doses of Obinutuzumab, which were discontinued due to their side effects. The patient reported excessive fatigue, temporal headache, nausea, vomiting, vertigo, tremor of the upper extremities, and head bobbing. Lumbar puncture was positive for CLL cells, and the CSF paraneoplastic panel was positive for KLHL11 antibodies, with a titer of 1:64. She received intravenous immunoglobulin, intravenous methylprednisolone, plasmapheresis, intravenous rituximab, and Zanubrutinib, with minimal response. She was then prescribed intrathecal rituximab, which caused slight clinical improvement. Complete response was noted via CSF cytology. About 4 months later, she underwent Ommaya placement and received intraventricular rituximab. Her symptoms persisted despite improvement in CSF cytology, likely due to persistent PNS that was difficult to treat. Conclusion KLHL11-PNS is a rare disease entity that often evolves clinically into treatment-refractory rhombencephalitis. Though PNS and LMD management strategies may overlap, their clinical outcomes may be discordant.

A Small Molecule Antagonist of CX3CR1 (KAND567) Inhibited the Tumor Growth-Promoting Effect of Monocytes in Chronic Lymphocytic Leukemia (CLL).

Nurse-like cells (NLCs) derived from monocytes in the tumor microenvironment support the growth of chronic lymphocytic leukemia (CLL) cells. Here, we investigated the effects of a CX3CR1 (fractalkine receptor) antagonist (KAND567) on autologous monocytes and their pro-survival effects on CLL cells in vitro. Plasma concentration of CX3CL1 was determined by ELISA and CX3CR1 expression by flow cytometry. CD19+ cells and autologous monocytes from patients with CLL and healthy donors were treated with KAND567 either in co-culture or alone. The apoptosis of CD19+ cells and monocytes was determined by Annexin V/PI staining and live-cell imaging. Plasma concentration of CX3CL1 (fractalkine) was significantly higher in patients with CLL (n = 88) than in healthy donors (n = 32) (p < 0.0001), with higher levels in patients with active compared to non-active disease (p < 0.01). CX3CR1 was found on monocytes but not B cells in patients and controls. Levels of intermediate and non-classical CX3CR1+ monocytes were higher in patients with CLL than in controls (p < 0.001), particularly in those with active disease (p < 0.0001). Co-culture experiments revealed that autologous monocytes promoted the survival of both malignant and normal B cells and that KAND567 selectively inhibited the growth of CLL cells in a dose-dependent manner but only in the presence of autologous monocytes (p < 0.05). Additionally, KAND567 inhibited the transition of monocytes to NLCs in CLL (p < 0.05). Our data suggest that the CX3CR1/CX3CL1 axis is activated in CLL and may contribute to the NLC-driven growth-promoting effects of CLL cells. KAND567, which is in clinical trials in other disorders, should also be explored in CLL.

NCMP-15. MULTIPLE HEMORRHAGIC CNS LESIONS IN A PATIENT WITH RELAPSED SYSTEMIC CHRONIC LYMPHOCYTIC LEUKEMIA

Abstract Although chronic lymphocytic leukemia (CLL) is the most common adult leukemia in Western countries, extramedullary CLL, characterized by the accumulation of clonal B cells outside of blood, bone marrow, and peripheral lymph nodes, remains rare. The central nervous system (CNS) is the most common site of extramedullary CLL involvement. However, clinically significant CLL in the CNS has been reported in fewer than 100 cases in the literature, and its true prevalence remains unknown with variable estimates. CLL in the CNS most often affects the meninges and usually spares the parenchyma unless there is a higher-grade/Richter transformation; in either case, it is typically not hemorrhagic. Furthermore, in the rare cases reported of hemorrhagic intraparenchymal CLL, patients present with isolated bleeding rather than multifocal hemorrhages. We present the case of a 63-year-old patient with multiply recurrent systemic CLL without Richter transformation who developed bilateral infratentorial and supratentorial micro and macrohemorrhages. Histopathology of a lesion showed focal subacute hemorrhage associated with reactive brain parenchyma containing CLL cells, though it was unclear whether the CLL predated the hemorrhage or if the hemorrhage introduced the CLL. Given the patient’s clinical stability, the lesions were ultimately attributed to coagulopathy in the context of CLL with subsequent secondary colonization of the hemorrhage by CLL cells. These lesions completely resolved after the patient underwent CLL-directed therapy three months after symptom onset. This case underscores the importance of considering bleeding risks associated with CLL and demonstrates that addressing the underlying CLL can lead to the improvement in bleeding sequelae.

Tumour assessment of ROR1 levels in various adult leukaemia and lymphoma types.

Receptor tyrosine kinase-like orphan receptor 1 (ROR1) is a tumour target currently used for the development of novel therapeutic modalities, such as antibody-drug conjugates, chimeric antigen receptor T-cell therapies, and others. Success of these new drugs depends on the selection of relevant indications based on ROR1 tumour prevalence, staining heterogeneity, and subcellular localization, among other parameters. We investigated ROR1 immunophenotype using validated antibody clones for immunohistochemistry (IHC) and flow cytometry (FC), analyzing 292 tumour specimens from 7 haematological malignancies and triple negative breast cancer (TNBC) as a reference solid tumour indication. ROR1 prevalence varied significantly across distinct tumour types, showing 100% of ROR1 positivity in all chronic lymphocytic leukaemia (n = 48) and hairy cell leukaemia (n = 14) specimens analyzed via FC with ranges between 1.1-99.8% and 0.8-62.1%, respectively. Samples analysed via IHC showed ROR1 membrane/cytoplasmic positivity in 44% of mantle cell lymphoma tumour samples (n = 27; H-score range: 10-285 in positive cases); 30% in TNBC (n = 46; H-score range: 1-200); 15% in diffuse large B-cell lymphoma (n = 45; H-score: 40-250); and 11% in follicular lymphoma (n = 34; H-score: 2-300). Finally, all acute myeloid leukaemia (n = 52) and most T-cell non-Hodgkin lymphoma (n = 31/32) tested samples were negative for ROR1 via IHC. In conclusion, ROR1 shows a heterogeneous tumour cell expression profile across multiple leukaemias and lymphomas, making it a tumour target that would require different patient selection strategies to develop novel therapeutic modalities.

Navigating the changing landscape of BTK-targeted therapies for B cell lymphomas and chronic lymphocytic leukaemia.

The B cell receptor (BCR) signalling pathway has an integral role in the pathogenesis of many B cell malignancies, including chronic lymphocytic leukaemia, mantle cell lymphoma, diffuse large B cell lymphoma and Waldenström macroglobulinaemia. Bruton tyrosine kinase (BTK) is a key node mediating signal transduction downstream of the BCR.The advent of BTK inhibitors has revolutionized the treatment landscape of B cell malignancies, with these agents often replacing highly intensive and toxic chemoimmunotherapy regimens as the standard of care. In this Review, we discuss the pivotal trials that have led to the approval of various covalent BTK inhibitors, the current treatment indications for these agents and mechanisms of resistance. In addition, we discuss novel BTK-targeted therapies, including covalent, as well as non-covalent, BTK inhibitors, BTK degraders and combination doublet and triplet regimens, to provide insights on the best current treatment paradigms in the frontline setting and at disease relapse.

Venetoclax dose escalation rapidly activates a BAFF/BCL-2 survival axis in chronic lymphocytic leukemia

AbstractVenetoclax, a first-in-class BH3 mimetic drug that targets BCL-2, has improved the outcomes of patients with chronic lymphocytic leukemia (CLL). Early measurements of the depth of the venetoclax treatment response, assessed by minimal residual disease, are strong predictors of long-term clinical outcomes. However, there are limited data on the early changes induced by venetoclax treatment that might inform strategies to improve responses. To address this gap, we conducted longitudinal mass cytometric profiling of blood cells from patients with CLL during the first 5 weeks of venetoclax monotherapy. At baseline, we resolved CLL heterogeneity at the single-cell level to define multiple subpopulations in all patients based on proliferative, metabolic, and cell survival proteins. Venetoclax induced a significant reduction in all CLL subpopulations and caused rapid upregulation of the prosurvival BCL-2, BCL-XL, and mantle cell lymphoma-1 proteins in surviving cells, which had reduced sensitivity to the drug. In mouse models, the venetoclax-induced elevation of survival proteins in B cells and CLL-like cells that persisted was recapitulated, and genetic models demonstrated that extensive apoptosis and access to the B cell cytokine, B cell activating factor (BAFF), were essential. Accordingly, in patients with CLL who were treated with venetoclax or the anti-CD20 antibody obinutuzumab there was marked elevation in BAFF and an increase in prosurvival proteins in leukemic cells that persisted. Overall, these data highlight the rapid adaptation of CLL cells to targeted therapies through homeostatic factors and support cotargeting of cytokine signals to achieve deeper and more durable long-term responses.

The Role of Changes in the Redox Status in the Pathogenesis of Chronic Lymphocytic Leukemia.

Chronic lymphocytic leukemia is a hemoblastosis of CD5+ B lymphocytes with lymphocytosis, damage to the lymphatic organs, occurring in the older age group, the etiology and pathogenesis of which are not fully understood. Oxidative stress is an important factor in the regulation of stem cells and the activation of intracellular survival signaling pathways in chronic lymphocytic leukemia cells. The aim of the study was to analyze the current data on the role of redox status changes in the pathogenesis of chronic lymphocytic leukemia. A review of published relevant studies 2018-2023, scientific articles in scientific electronic bibliographic databases PubMed and Social Sciences Citation Index, devoted to the pathogenesis of chronic lymphocytic leukemia and the role of free-radical oxidation processes in it was carried out. In chronic lymphocytic leukemia, oxidative stress with a systemic excess of reactive oxygen species, an imbalance in the effectiveness of antioxidant defense is caused mainly by activation of oxidative phosphorylation in mitochondria, low levels of NADPH-oxidase type 2, increased expression of heme oxygenase-1, glutathione peroxidase and glutathione recycling enzymes, superoxide dismutase-2, thioredoxins and decreased expression of catalase. One of the mechanisms of resistance to drug therapy and oxidative stress of chronic lymphocytic leukemia cells is the intracellular signaling pathway dependent on erythroid nuclear factor-2, due to the activation of expression in cells of superoxide dismutase-2, catalase, glutathione peroxidase, peroxiredoxin-3 and-5, heme oxygenase-1, thioredoxin-1 and -2, reduced glutathione, natural killer cell activity, which is associated with lifespan, chemotaxis, proliferation, and survival. FOXO family proteins are believed to suppress carcinogenesis. FOXO3a increases the expression of superoxide dismutase-2, catalase, glutathione peroxidase, peroxiredoxin-3 and -5, and the activity of natural killer cells, which promotes the survival of tumor cells. The development of new targeted pharmacological agents that are capable of accumulating reactive oxygen species and reducing antioxidant protection due to the degradation of erythroid nuclear factor-2 and activation of NADPH-quinone oxidoreductase-1 is underway, which modernizes the therapy of chronic lymphocytic leukemia.

Cardiovascular and non-cardiovascular adverse events in patients with hematologic malignacies treated with BTK inhibitors: a real-world analysis

Abstract Background Bruton tyrosine kinase (BTK) inhibitors play an important role in targeted treatment of B-cell lymphoproliferative disorders. However, adverse events may limit the proper course of treatment in many patients. Purpose To compare the risk of cardiovascular and non-cardiovascular adverse events in patients with chronic lymphocytic leukemia (CLL) or small cell lymphocytic lymphoma (SLL) treated with first-generation BTK inhibitor ibrutinib versus second-generation acalabrutinib, using real-world data from electronic medical records. Methods We used data from a large collaborative multinational network ( TriNetX), that emcompasses more than 100 healthcare organizations worldwide. We queried the databank for patients aged ≥ 18 years with chronic lymphocytic leukemia or small-cell lymphomas treated with ibrutinib or acalabrutinib in the past 10 years before the analysis. We used propensity score matching to balance the cohorts. The 3-year cumulative incidences and hazard ratios for the following outcomes were calculated: atrial flutter or fibrillation, other arrhythmias, heart failure, ischemic stroke or peripheral embolism, acute coronary syndrome, bleeding, and sepsis. Results We compared 2,107 patients in each group. The 3-year incidences of atrial fibrillation or flutter in the acalabrutinib and ibrutinib groups were 7.11% and 14.78% respectively, with a lower ratio in patients treated with acalabrutinib than those treated with ibrutinib (hazard ratio, HR 0.68, 95% CI 0.55-0.84). New-onset hypertension occurred during the 3-year follow-up in 16.29% patients in the acalabrutinib group versus 27.8% patients in the ibrutinib group (HR 0,81, 95% CI 0.66-0.98). The incidence of sepsis was 6.49% in patients treated with acalabrutinib versus 11.37% in those treated with ibrutinib group (HR 0.77, 95% CI 0.60-0.98). Concerning the other adverse events, there were no significant differences between the two groups. Conclusions In this large real-world analysis, patients with CLL or SLL treated with acalabrutinib had a better cardiovascular and non-cardiovascular safety profile than those treated with ibrutinib, with lower incidence of atrial flutter or fibrillation, new-onset arterial hypertension, and sepsis.Figure 1.Cardiovascular outcomesFigure 2.Non-cardiovascular outcomes

Apoliprotein E-mediated ferroptosis controls cellular proliferation in chronic lymphocytic leukemia.

Unraveling vulnerabilities in chronic lymphocytic leukemia (CLL) represents a key approach to understand molecular basis for its indolence and a path toward developing tailored therapeutic approaches. In this study, we found that CLL cells are particularly sensitive to the inhibitory action of abundant serum protein, apolipoprotein E (ApoE). Physiological concentrations of ApoE affect CLL cell viability and inhibit CD40-driven proliferation. Transcriptomics of ApoE-treated CLL cells revealed a signature of redox and metal disbalance which prompted us to explore the underlying mechanism of cell death. We discover, on one hand, that ApoE treatment of CLL cells induces lipid peroxidation and ferroptosis. On the other hand, we find that ApoE is a copper-binding protein and that intracellular copper regulates ApoE toxicity. ApoE regulation tends to be lost in aggressive CLL. CLL cells from patients with high leukocyte counts are less sensitive to ApoE inhibition, while resistance to ApoE is possible in transformed CLL cells from patients with Richter syndrome (RS). Nevertheless, both aggressive CLL and RS cells maintain sensitivity to drug-induced ferroptosis. Our findings suggest a natural suppression axis that mediates ferroptotic disruption of CLL cell proliferation, building up the rationale for choosing ferroptosis as a therapeutic target in CLL and RS.

Drug-Induced Differential Gene Expression Analysis on Nanoliter Droplet Microarrays: Enabling Tool for Functional Precision Oncology.

Drug-induced differential gene expression analysis (DGEA) is essential for uncovering the molecular basis of cell phenotypic changes and understanding individual tumor responses to anticancer drugs. Performing high throughput DGEA is challenging due to the high cost and labor-intensive multi-step sample preparation protocols. In particular, performing drug-induced DGEA on cancer cells derived from patient biopsies is even more challenging due to the scarcity of available cells. A novel, miniaturized, nanoliter-scale method for drug-induced DGEA is introduced, enabling high-throughput and parallel analysis of patient-derived cell drug responses, overcoming the limitations and laborious nature of traditional protocols. The method is based on the Droplet Microarray (DMA), a microscope glass slide with hydrophilic spots on a superhydrophobic background, facilitating droplet formation for cell testing. DMA allows microscopy-based phenotypic analysis, cDNA extraction, and DGEA. The procedure includes cell lysis for mRNA isolation and cDNA conversion followed by droplet pooling for qPCR analysis. In this study, the drug-induced DGEA protocol on the DMA platform is demonstrated using patient-derived chronic lymphocytic leukemia (CLL) cells. This methodology is critical for DGEA with limited cell numbers and promise for applications in functional precision oncology. This method enables molecular profiling of patient-derived samples after drug treatment, crucial for understanding individual tumor responses to anticancer drugs.

The DLEU2/miR-15a/miR-16-1 cluster shapes the immune microenvironment of chronic lymphocytic leukemia

The development and progression of chronic lymphocytic leukemia (CLL) depend on genetic abnormalities and on the immunosuppressive microenvironment. We have explored the possibility that genetic drivers might be responsible for the immune cell dysregulation that shapes the protumor microenvironment. We performed a transcriptome analysis of coding and non-coding RNAs (ncRNAs) during leukemia progression in the Rag2−/−γc−/− MEC1-based xenotransplantation model. The DLEU2/miR-16 locus was found downmodulated in monocytes/macrophages of leukemic mice. To validate the role of this cluster in the tumor immune microenvironment, we generated a mouse model that simultaneously mimics the overexpression of hTCL1 and the germline deletion of the minimal deleted region (MDR) encoding the DLEU2/miR-15a/miR-16-1 cluster. This model provides an innovative and faster CLL system where monocyte differentiation and macrophage polarization are exacerbated, and T-cells are dysfunctional. MDR deletion inversely correlates with the levels of predicted target proteins including BCL2 and PD1/PD-L1 on murine CLL cells and immune cells. The inverse correlation of miR-15a/miR-16-1 with target proteins has been confirmed on patient-derived immune cells. Forced expression of miR-16-1 interferes with monocyte differentiation into tumor-associated macrophages, indicating that selected ncRNAs drive the protumor phenotype of non-malignant immune cells.

FoxO1/Rictor axis induces a non-genetic adaptation to Ibrutinib via Akt activation in chronic lymphocytic leukemia.

BTK inhibitor therapy induces peripheral blood lymphocytosis in chronic lymphocytic leukemia (CLL) lasting for several months. It remains unclear whether non-genetic adaptation mechanisms exist, allowing CLL cells' survival during BTK inhibitor-induced lymphocytosis and/or playing a role in therapy resistance. We show that in approximately 70 % of CLL cases, ibrutinib treatment in vivo increases Akt activity above pre-therapy levels within several weeks, leading to compensatory CLL cell survival and a more prominent lymphocytosis on therapy. Ibrutinib-induced Akt phosphorylation (pAktS473) is caused by the upregulation of FoxO1 transcription factor, which induces expression of Rictor, an assembly protein for mTORC2 protein complex that directly phosphorylates Akt at serine 473 (S473). Knock-out or inhibition of FoxO1 or Rictor led to a dramatic decrease in Akt phosphorylation and growth disadvantage for malignant B cells in the presence of ibrutinib (or PI3K inhibitor idelalisib) in vitro and in vivo. FoxO1/Rictor/pAktS473 axis represents an early non-genetic adaptation to BCR inhibitor therapy not requiring PI3Kδ or BTK kinase activity. We further demonstrate that FoxO1 can be targeted therapeutically, and its inhibition induces CLL cells' apoptosis alone or in combination with BTK inhibitors (ibrutinib, acalabrutinib, pirtobrutinib) and blocks their proliferation triggered by T-cell factors (CD40L, IL-4, and IL-21).

Experimental and theoretical investigation of Chronic Lymphocytic Leukemia cell's viscoelastic contact mechanics using atomic force microscope

Chronic Lymphocytic Leukemia (CLL) is a type of cancer usually appearing in old age. In this research, a method for detecting CLL cells in young age through the analysis of geometrical and mechanical properties of human Leukocytes has been presented. For this purpose, the CLL cells are cultured and their geometric characteristics, adhesion force, and contact behavior have been examined using an Atomic Force Microscope (AFM) device. Subsequently, the obtained experimental results have been compared with the geometric and mechanical properties of Leukocytes. Furthermore, the manipulation process has been mathematically modeled using different adhesive and non-adhesive contact theories. The results showed that blood cancer cells have up to 8.17% smaller dimensions and up to 23.57% greater elastic modulus compared to leukocytes.

The NOTCH1 and miR-34a signaling network is affected by TP53 alterations in CLL

In chronic lymphocytic leukemia (CLL), TP53 mutations or deletions on chromosome 17p lead to adverse prognosis and reduced levels of miR-34a, which targets NOTCH1. Also, hyperactivated NOTCH1 signaling is crucial for CLL progression. Here we explored the interaction between p53, miR-34a, and NOTCH1 in CLL. We investigated the effect of p53 and miR-34a on NOTCH1 signaling and expression in CLL cells with altered TP53. Our results indicate that miR-34a reduces NOTCH1 3’ UTR activity but might not be a mediator between p53 signaling and NOTCH1. p53 activation increases miR-34a expression and NOTCH1 protein levels, correlating with decreased NOTCH1 and miR-34a levels in primary CLL cells with TP53 alterations. Some samples with high NOTCH1 levels presented increased BCL-2, suggesting an anti-apoptotic mechanism of a potentially direct p53-NOTCH1 relation in CLL. This study deepens the understanding of the p53-miR-34a-NOTCH1 signaling network, providing insights that could guide future therapeutic strategies for CLL.

Patient-Specific Nanoparticle Targeting in Human Leukemia Blood.

Antibody-directed targeting of chemotherapeutic nanoparticles to primary human cancers holds promise for improving efficacy and reducing off-target toxicity. However, clinical responses to targeted nanomedicines are highly variable. Herein, we prepared and examined a matrix of 9 particles (organic and inorganic particles of three surface chemistries with and without antibody functionalization) and developed an ex vivo model to study the person-specific targeting of nanoparticles in whole blood of 15 patients with chronic lymphocytic leukemia (CLL). Generally, anti-CD20-functionalized poly(ethylene glycol) (PEG) nanoparticles efficiently targeted CLL cells, leading to low off-target phagocytosis by granulocytes and monocytes in the blood. However, there was up to 164-fold patient-to-patient variability in the CLL targeting. This was further exemplified through using clinically relevant PEGylated doxorubicin-encapsulated liposomes, which showed high interpersonal differences in CLL targeting (up to 234-fold differences) and off-target phagocytosis (up to 65- and 112-fold differences in granulocytes and monocytes, respectively). Off-target phagocytosis led to almost all monocytes being killed within 24 h of treatment. Variance of the off-target association of PEGylated liposomes with granulocytes and monocytes significantly correlated to anti-PEG immunoglobulin G levels in the blood of CLL patients. A negative correlation between CLL targeting of PEG particles and anti-PEG immunoglobulin M levels was found in the blood. Taken together, our study identifies anti-PEG antibodies as key proteins in modulating patient-specific targeting of PEGylated nanoparticles in human leukemia blood. Other factors, such as the antigen expression of targeted cells and fouling properties of nanoparticles, also play an important role in patient-specific targeting. The human leukemia blood assay we developed provides an ex vivo model to evaluate interpersonal variances in response to targeted nanomedicines.

Potential impact of NOTCH1 activation on venetoclax sensitivity in chronic lymphocytic Leukaemia: Invitro insights and clinical implications.

Despite significant progress in treating chronic lymphocytic leukaemia (CLL), resistance to therapy remains challenging. NOTCH1 activation, common in CLL, confers adverse prognosis. This study explores the impact of NOTCH1 signalling on venetoclax sensitivity invitro. Although NOTCH1 activation minimally impaired the susceptibility of CLL cells to venetoclax, exvivo cell competition studies reveal that cells with constitutive NOTCH1 activation outgrew their wild-type counterparts in the presence of ongoing venetoclax exposure. Our findings suggest that while NOTCH1 activation is insufficient to confer venetoclax refractoriness, there is enhanced potential for cells with NOTCH1 activation to escape and thus become fully resistant to venetoclax.

Co-expression of CD69, CD49d, CD279 and CD20 in chronic lymphocytic leukemia cells is a new biomarker of active disease before or under therapy.

Not available.

The non-canonical BAF chromatin remodeling complex is a novel target of spliceosome dysregulation in SF3B1-mutated chronic lymphocytic leukemia

SF3B1 mutations are recurrent in chronic lymphocytic leukemia (CLL), particularly enriched in clinically aggressive stereotyped subset #2. To investigate their impact, we conducted RNA-sequencing of 18 SF3B1MUT and 17 SF3B1WT subset #2 cases and identified 80 significant alternative splicing events (ASEs). Notable ASEs concerned exon inclusion in the non-canonical BAF (ncBAF) chromatin remodeling complex subunit, BRD9, and splice variants in eight additional ncBAF complex interactors. Long-read RNA-sequencing confirmed the presence of splice variants, and extended analysis of 139 CLL cases corroborated their association with SF3B1 mutations. Overexpression of SF3B1K700E induced exon inclusion in BRD9, resulting in a novel splice isoform with an alternative C-terminus. Protein interactome analysis of the BRD9 splice isoform revealed augmented ncBAF complex interaction, while exhibiting decreased binding of auxiliary proteins, including SPEN, BRCA2, and CHD9. Additionally, integrative multi-omics analysis identified a ncBAF complex-bound gene quartet on chromosome 1 with higher expression levels and more accessible chromatin in SF3B1MUT CLL. Finally, Cancer Dependency Map analysis and BRD9 inhibition displayed BRD9 dependency and sensitivity in cell lines and primary CLL cells. In conclusion, spliceosome dysregulation caused by SF3B1 mutations leads to multiple ASEs and an altered ncBAF complex interactome, highlighting a novel pathobiological mechanism in SF3B1MUT CLL.