Molecular pathogenesis of chronic lymphocytic leukemia

Noncoding RNAs in B cell non-Hodgkins lymphoma

B-cell non-Hodgkins lymphomas (BCNHLs) are a category of B-cell cancers that show heterogeneity. These blood disorders are derived from different levels of B-cell maturity. Among NHL cases, ∼80-90 % are derived from B-cells. Recent studies have demonstrated that noncoding RNAs (ncRNAs) contribute to almost all parts of mechanisms and are essential in tumorigenesis, including B-cell non-Hodgkins lymphomas. The study of ncRNA dysregulations in B-cell lymphoma unravels important mysteries in lymphoma's molecular etiology. It seems also necessary for discovering novel trials as well as investigating the potential of ncRNAs as markers for their diagnosis and prognosis. In the current study, we summarize the role of ncRNAs involving miRNAs, long noncoding RNAs, as well as circular RNAs in the development or progression of BCNHLs.

Landscape of NOTCH1 Mutations and Co-occurring Biomarker Alterations in Chronic Lymphocytic Leukemia

NOTCH1 is one of the most frequently mutated genes in chronic lymphocytic leukemia and has emerged as a marker of poor prognosis. In addition to coding NOTCH1 mutations involving exon 34, non-coding NOTCH1 mutations involving the 3' UTR have been described in a limited number of chronic lymphocytic leukemia (CLL) patients and were associated with adverse outcomes. In this study, 1574 CLL patients were assessed using targeted sequencing with a 29 gene panel and the results were correlated with prognostic characteristics. NOTCH1 mutations were detected in 252 (16%) patients, including both coding (220/252, 14%), non-coding (24/252, 1.5%) and a mixture of coding and non-coding (8/252, 0.5%) NOTCH1 mutations. NOTCH1 mutations were more commonly seen in patients with unmutated IGHV, ZAP70 positivity and CD38 positivity. Mixed NOTCH1 mutations were also more commonly seen in patients with unmutated IGHV and ZAP70. There was no association between mixed NOTCH1 mutations and CD38 expression in this cohort. The most common cytogenetic alteration detected in patients with coding and mixed NOTCH1 mutations was trisomy 12, whereas del13q was the most common cytogenetic alteration detected in patients with non-coding NOTCH1 mutation. The most common gene mutations co-occurring with coding NOTCH1 mutations were: TP53 (23.2%), SF3B1 (16.4%) and SPEN (10%). The most common gene mutations co-occurring with non-coding NOTCH1 mutations were: SF3B1 11(34.4%), ATM 4(12.5%) and TP53 4(12.5%). CLL patients with clonal coding and non-coding NOTCH1 mutations had a significantly shorter time-to-first treatment than patients with wild type NOTCH1 (4.3 vs 10.0 years and 0.9 vs 10.0 years respectively, p < 0.05). Similarly, CLL patients with subclonal coding NOTCH1 mutations had a significantly shorter time-to-first treatment than patients with wild type NOTCH1 (5.6 vs 10.0 years, p < 0.05). CLL patients with subclonal non-coding NOTCH1 mutations also had a shorter time-to-first treatment than patients with wild type NOTCH1 mutations, however, the difference was not significant (5.1 vs 10.0 years, p = 0.15). These data confirm that both coding and non-coding NOTCH1 mutations carry adverse prognostic impact and need to be included in sequencing assays performed for the prognostic workup of CLL patients.

Notch2 Increases the Resistance to Venetoclax-Induced Apoptosis in Chronic Lymphocytic Leukemia B Cells by Inducing Mcl-1

Chronic lymphocytic leukemia (CLL) has experienced a clinical revolution—thanks to the discovery of crucial pathogenic mechanisms. CLL is still an incurable disease due to intrinsic or acquired resistance of the leukemic clone. Venetoclax is a Bcl-2 inhibitor with a marked activity in CLL, but emerging patterns of resistance are being described. We hypothesize that intrinsic features of CLL cells may contribute to drive mechanisms of resistance to venetoclax. We analyzed the expression of Interferon Regulatory Factor 4 (IRF4), Notch2, and Mcl-1 in a cohort of CLL patients. We evaluated CLL cell viability after genetic and pharmaceutical modulation of Notch2 expression in patients harboring trisomy 12. We tested venetoclax in trisomy 12 CLL cells either silenced or not for Notch2 expression or in combination with an inhibitor of Mcl-1, AMG-176. Trisomy 12 CLL cells were characterized by low expression of IRF4 associated with high levels of Notch2 and Mcl-1. Notch2 and Mcl-1 expression determined protection of CLL cells from spontaneous and drug-induced apoptosis. Considering the involvement of Mcl-1 in venetoclax resistance, our data demonstrated a contribution of high levels of Notch2 and Mcl-1 in a reduced response to venetoclax in CLL cells carrying trisomy 12. Furthermore, reduction of Mcl-1 expression by silencing Notch2 or by treatment with AMG-176 was able to restore the response of CLL cells to venetoclax. The expression of Notch2 identifies a subset of CLL patients, mainly harboring trisomy 12, characterized by high levels of Mcl-1. This biological mechanism may compromise an effective response to venetoclax.

Experimental Validation of a Mathematical Model to Describe the Drug Cytotoxicity of Leukemic Cells

Chlorambucil (Chl), Melphalan (Mel), and Cytarabine (Cyt) are recognized drugs used in the chemotherapy of patients with advanced Chronic Lymphocytic Leukemia (CLL). The optimal treatment schedule and timing of Chl, Mel, and Cyt administration remains unknown and has traditionally been decided empirically and independently of preclinical in vitro efficacy studies. As a first step toward mathematical prediction of in vivo drug efficacy from in vitro cytotoxicity studies, we used murine A20 leukemic cells as a test case of CLL. We first found that logistic growth best described the proliferation of the cells in vitro. Then, we tested in vitro the cytotoxic efficacy of Chl, Mel, and Cyt against A20 cells. On the basis of these experimental data, we found the parameters for cancer cell death rates that were dependent on the concentration of the respective drugs and developed a mathematical model involving nonlinear ordinary differential equations. For the proposed mathematical model, three equilibrium states were analyzed using the general method of Lyapunov, with only one equilibrium being stable. We obtained a very good symmetry between the experimental results and numerical simulations of the model. Our novel model can be used as a general tool to study the cytotoxic activity of various drugs with different doses and modes of action by appropriate adjustment of the values for the selected parameters.

13q14 Deletion and Its Effect on Prognosis of Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is the most common leukemia affecting adults. CLL results due to uncontrolled accumulation of B lymphocytes in the body with the clinical spectrum ranging from comparatively benign disease to an aggressive form. The disease pathogenesis lies in molecular genetics, the most common alteration being the deletion in the long arm of chromosome 13, at position 14 (13q14) region. This deletion leads to the loss of important microRNAs which are involved in maintaining the critical balance of the apoptosis mechanism of cell death of B lymphocytes. As such, the imbalance contributes towards B cells' immortality and, thus, CLL arises. This significant 13q14 deletion contributes to CLL's pathogenesis and paves the way for CLL treatment, hence affecting the prognosis of the affected patients.

Furthermore, the size of deletion of the long arm of chromosome 13 (13q) has a remarkable effect on its prognosis and therapeutic intervention. The minimal deleted region (MDR)/small deletion or long 13q loss/mutation, and biallelic 13q deletion or monoallelic 13q deletion are commonly seen. 13q14 deletion is an initiating defect targeting tumor suppressor gene locus deleted in lymphocytic leukemia 2 (DLEU2))/microRNA15A (MIR15A)/microRNA 16-1 (MIR 16-1). Regarding CLL treatment, conventional therapy with alkylating agents has been used for a long time, which reported low- to non-existent complete remission rates and adverse events after prolonged use. Moreover, research into the 13q14 deletion has also provided new insights into the molecular genetics and pathways that interact in such a way, making it possible to transform healthy cells into malignant cells in an entirely new fashion with a complete disregard to its original form, resulting in CLL.

O-GlcNAcylation in early stages of chronic lymphocytic leukemia; protocol development for flow cytometry

BACKGROUND

Recent studies proved that metabolic changes in malignant disorders have an impact on protein glycosylation, however, only a few attempts have been made so far to use O-GlcNAc analysis as a prognostic tool. Glucose metabolism is reported to be altered in hematological malignancies thus, we hypothesized that monitoring intracellular O-GlcNAc levels in Rai stage 0-I (Binet A) CLL patients could give deeper insights regarding subtle metabolic changes of progression which are not completely detected by the routine follow-up procedures.

OBJECTIVE

In this proof of concept study we established a flow cytometric detection method for the assessment of O-GlcNAcylation as a possible prognostic marker in CLL malignancy which was supported by fluorescence microscopy.

METHODS

Healthy volunteers and CLL patients were recruited for this study. Lymphocytes were isolated, fixed and permeabilised by various methods to find the optimal experimental condition for O-GlcNAc detection by flow cytometry. O-GlcNAc levels were measured and compared to lymphocyte count and various blood parameters including plasma glucose level.

RESULTS

The protocol we developed includes red blood cell lysis, formalin fixation, 0.1% Tween 20 permeabilisation and employs standardized cell number per sample and unstained controls. We have found significant correlation between O-GlcNAc levels and WBC (R2= 0.8535, p< 0.0029) and lymphocyte count (R2= 0.9225, p< 0.0006) in CLL patients. Interestingly, there was no such correlation in healthy individuals (R2= 0.05664 for O-GlcNAc vs WBC and R2= 0.04379 for O-GlcNAc vs lymphocytes).

CONCLUSION

Analyzing O-GlcNAc changes in malignant disorders, specifically in malignant hematologic diseases such as CLL, could be a useful tool to monitor the progression of the disease.

αvβ3 Integrin Expression and Mitogenic Effects by Thyroid Hormones in Chronic Lymphocytic Leukemia

Background: Chronic lymphocytic leukemia (CLL) is the most common adult leukemia. The thyroid hormones, T3 and T4, bind the αvβ3 integrin and activate phosphorylates ERK (pERK). These tumor-promoting actions were reported in a number of malignancies, but not in CLL. Methods: Primary cells from 22 CLL patients were verified for disease markers (CD5/CD19/CD23) and analyzed for αvβ3 by flow cytometry (FC), ImageStream, Western blots (WB), and immunohistochemistry (IHC) in archival bone marrow (BM, n = 6) and lymph node (LN, n = 5) tissues. Selected samples (n = 8) were incubated with T3 (1–100 nM) or T4 (0.1–10 µM) for 30 min, and the expression levels of αvβ3, pERK and PCNA (cell proliferation marker) were determined (WB). Results: αvβ3 was detected on the membrane of circulating CLL cells and in the BM but not in the LN. T3 and T4 enhanced αvβ3 protein levels in primary CLL cells. Similarly, pERK and PCNA were rapidly induced in response to T3 and T4 exposure. Conclusions: αvβ3 integrin is expressed on primary CLL cells and is induced by thyroid hormones. We further suggest that the hormones are mitogenic in these cells, presumably via αvβ3-mediated signaling.

Non-coding RNAs (miRNAs and lncRNAs) and their roles in lymphogenesis in all types of lymphomas and lymphoid malignancies

Contemporary developments in molecular biology have been combined with discoveries on the analysis of the role of all non-coding RNAs (ncRNAs) in human diseases, particularly in cancer, by examining their roles in cells. Currently, included among these common types of cancer, are all the lymphomas and lymphoid malignancies, which represent a diverse group of neoplasms and malignant disorders. Initial data suggest that non-coding RNAs, particularly long ncRNAs (lncRNAs), play key roles in oncogenesis and that lncRNA-mediated biology is an important key pathway to cancer progression. Other non-coding RNAs, termed microRNAs (miRNAs or miRs), are very promising cancer molecular biomarkers. They can be detected in tissues, cell lines, biopsy material and all biological fluids, such as blood. With the number of well-characterized cancer-related lncRNAs and miRNAs increasing, the study of the roles of non-coding RNAs in cancer is bringing forth new hypotheses of the biology of cancerous cells. For the first time, to the best of our knowledge, the present review provides an up-to-date summary of the recent literature referring to all diagnosed ncRNAs that mediate the pathogenesis of all types of lymphomas and lymphoid malignancies.

Revisiting Richter transformation in the era of novel CLL agents

Richter transformation (RT) is the development of aggressive lymphoma - most frequently diffuse large B-cell lymphoma (DLBCL) and rarely Hodgkin lymphoma (HL) - arising on the background of chronic lymphocytic leukaemia (CLL). Despite recent advances in CLL treatment, RT also develops in patients on novel agents, usually occurring as an early event. RT incidence is lower in CLL patients treated with novel agents in the front line compared to relapsed/refractory cases, with a higher incidence in patients with TP53 disruption. The genetic heterogeneity and complexity are higher in RT-DLBCL than CLL; the genetics of RT-HL are largely unknown. In addition to TP53, aberrations in CDKN2A, MYC, and NOTCH1 are common in RT-DLBCL; however, no distinct RT-specific genetic aberration is recognised yet. RT-DLBCL on ibrutinib is frequently associated with BTK and PLCG2 mutations. Here, we update on genetic analysis, diagnostics and treatment options in RT in the era of novel agents.

Nurse-Like Cells and Chronic Lymphocytic Leukemia B Cells: A Mutualistic Crosstalk inside Tissue Microenvironments

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in Western countries and is an example of hematological disease where cooperation between genetic defects and tumor microenvironmental interaction is involved in pathogenesis. CLL is a disease that is considered as “addicted to the host”; indeed, the crosstalk between leukemic cells and the tumor microenvironment is essential for leukemic clone maintenance supporting CLL cells’ survival, proliferation, and protection from drug-induced apoptosis. CLL cells are not innocent bystanders but actively model and manipulate the surrounding microenvironment to their own advantage. Besides the different players involved in this crosstalk, nurse-like cells (NLC) resemble features related to leukemia-associated macrophages with an important function in preserving CLL cell survival and supporting an immunosuppressive microenvironment. This review provides a comprehensive overview of the role played by NLC in creating a nurturing and permissive milieu for CLL cells, illustrating the therapeutic possibilities in order to specifically target and re-educate them.

A long-term study of AAV gene therapy in dogs with hemophilia A identifies clonal expansions of transduced liver cells

Nine dogs with hemophilia A were treated with adeno-associated viral (AAV) gene therapy and followed for up to 10 years. Administration of AAV8 or AAV9 vectors expressing canine factor VIII (AAV-cFVIII) corrected the FVIII deficiency to 1.9-11.3% of normal FVIII levels. In two of nine dogs, levels of FVIII activity increased gradually starting about 4 years after treatment. None of the dogs showed evidence of tumors or altered liver function. Analysis of integration sites in liver samples from six treated dogs identified 1,741 unique AAV integration events in genomic DNA and expanded cell clones in five dogs, with 44% of the integrations near genes involved in cell growth. All recovered integrated vectors were partially deleted and/or rearranged. Our data suggest that the increase in FVIII protein expression in two dogs may have been due to clonal expansion of cells harboring integrated vectors. These results support the clinical development of liver-directed AAV gene therapy for hemophilia A, while emphasizing the importance of long-term monitoring for potential genotoxicity.

Validation and interpretation of IGH and TCR clonality testing by Ion Torrent S5 NGS for diagnosis and disease monitoring in B and T cell cancers

Cancers of B and T lymphocytes are the most common hematologic malignancies in the US. Molecular assays for assessing clonal rearrangements of the immunoglobulin receptor (IGH) and T-cell receptor (TCR), commonly referred to as B- and T-cell clonality, as well as determination of IGH somatic mutation status, enables improved diagnostic accuracy and disease monitoring. Here we describe validation of NGS LymphoTrack (IGH, TCRG, Invivoscribe, Inc) with Ion Torrent S5 sequencing, which employs a different sequencing chemistry and has not been previously reported for NGS clonality to our knowledge. We also demonstrate the concordance of clonality by LymphoTrack with S5 sequencing with other molecular methodologies and with clinical measurements of disease. We show that LymphoTrack with S5 sequencing identifies previously detected IGH and TCRG clonal sequences across matched biopsy specimens and clinical timepoints, enabling more precise and sensitive disease monitoring for B- and T-cell cancers compared to PCR fragment or capillary sequencing. In sum, our study demonstrates that the LymphoTrack assays with Ion Torrent S5 sequencing 1) can be used successfully for IGH and TCR clonality with reproducible results; 2) generates and quantifies clonal sequences to enable highly precise comparison of samples; 3) are substantially more sensitive than PCR fragment and return clonality results in specimens that failed PCR fragment assays; and 4) the TCRG assays are highly concordant with clinical and histopathologic diagnoses. Taken together, the LymphoTrack with Ion S5 NGS clonality assays offer a sensitive and precise method for diagnostic testing and disease monitoring in B- and T-cell cancers.

The relationship between oxidative stress and cytogenetic abnormalities in B-cell chronic lymphocytic leukemia

BACKGROUND

Prospective data on the value of oxidative stress in the pathogenesis of B-CLL are limited, and data on the relationship between oxidative stress and the presence of cytogenetic abnormalities (CA) in this pathology are almost absent. In the present study, we evaluated the serum levels of oxidative stress biomarkers [conjugated dienes (CD), malondialdehyde (MDA), and nitrite levels] and antioxidant biomarkers [ceruloplasmin (CP) level and glutathione peroxidase (GPx) activity] in B-CLL and investigated the relationship between these biomarkers and the presence of CA.

MATERIAL AND METHODS

A total of 64 B-CLL patients were grouped with respect to the Rai stages of the disease, then to the mutated/unmutated status of IGHV genes as well as to the presence/absence of CA. The type and frequency of CA in the B-CLL cells were determined by fluorescence in situ hybridization. Control group included 30 healthy volunteers. The CD, MDA, and nitrite levels as well as the GPx activity were evaluated spectrophotometrically; the CP level was evaluated turbidimetrically.

RESULTS

Compared to control, the B-CLL patients had increased CD, MDA, and nitrite levels as well as increased CP level and decreased GPx activity, which was observed at all Rai stages of the disease. CA were identified in 47 patients: del(13q14.3) as a single CA occurred in 18 patients, del(11q22.3) in 5 patients, del(17p13.1) in 4 patients, tri 12 in 5 patients, and multiple CA occurred in 15 patients. Compared to patients without CA, isolated del(17p13.1) was associated with higher CD and MDA levels while multiple CA with elevated CD levels only. The nitrite and CP levels and the activity of GPx in patients with CA were close to those in patients with normal FISH. The odds of harboring CA increased by a factor of 1.88 (p = 0.004) for every one unit increase in serum CD level (μmol/L), as assessed by binomial logistic regression.

CONCLUSION

The results indicate that B-CLL patients experience increased oxidative stress and the relative deficiency of the antioxidant defense system. Increased CD level was independently associated with greater likelihood of harboring CA.

Targeting chronic lymphocytic leukemia with N-methylated thrombospondin-1-derived peptides overcomes drug resistance

Chronic lymphocytic leukemia (CLL), the most common adulthood leukemia in Western countries, is a very heterogeneous disease characterized by a peripheral accumulation of abnormal CD5+ B lymphocytes in the immune system. Despite new therapeutic developments, there remains an unmet medical need for CLL. Here, we demonstrate that the use of N-methylated thrombospondin-1 (TSP-1)-derived peptides is an efficient way to kill the malignant CLL cells, including those from high-risk individuals with poor clinical prognosis, del11q, del17p, 2p gain, or complex karyotype. PKT16, our hit N-methylated peptide, triggers the elimination of the leukemic cells, sparing the nontumor cells, including the hematopoietic precursors, and reduces the in vivo tumor burden of a CLL-xenograft mice model. A complementary analysis underscores the improved cytotoxic efficiency of PKT16 compared with the previously described TSP-1-derived probes, such as PKHB1. PKT16 elicits an original caspase-independent programmed necrotic mode of cell death, different from necroptosis or ferroptosis, implicating an intracellular Ca2+ deregulation that provokes mitochondrial damage, cell cycle arrest, and the specific death of the malignant CLL cells. The activation of the Gαi proteins and the subsequent drop of cyclic adenosine monophosphate levels and protein kinase A activity regulate this cytotoxic cascade. Remarkably, PKT16 induces the molecular hallmarks of immunogenic cell death, as defined by the calreticulin plasma membrane exposure and the release of adenosine triphosphate and high-mobility group box 1 protein from the dying CLL cells. Thus, PKT16 appears to be able to stimulate an anticancer in vivo immune response. Collectively, our results pave the way toward the development of an efficient strategy against CLL.

Bispecific, T-Cell-Recruiting Antibodies in B-Cell Malignancies

Bispecific antibodies (BsAbs) are designed to recognize and bind to two different antigens or epitopes. In the last few decades, BsAbs have been developed within the context of cancer therapies and in particular for the treatment of hematologic B-cell malignancies. To date, more than one hundred different BsAb formats exist, including bispecific T-cell engagers (BiTEs), and new constructs are constantly emerging. Advances in protein engineering have enabled the creation of BsAbs with specific mechanisms of action and clinical applications. Moreover, a better understanding of resistance and evasion mechanisms, as well as advances in the protein engineering and in immunology, will help generating a greater variety of BsAbs to treat various cancer types. This review focuses on T-cell-engaging BsAbs and more precisely on the various BsAb formats currently being studied in the context of B-cell malignancies, on ongoing clinical trials and on the clinical concerns to be taken into account in the development of new BsAbs.

Impact Of TP53 Gene Promoter Methylation On Chronic Lymphocytic Leukemia Pathogenesis And Progression

Background

Chronic lymphocytic leukemia (CLL) is a malignant lymphoid disorder that results from the overgrowth of mature-looking lymphoid cells in the blood and lymphatic tissue. Various clinical presentations have been attributed to the disease as a result of the different underlying genetic and epigenetic alterations. The current study has been initiated to study the role of an epigenetic alteration affecting the promoter of the TP53gene on CLL pathogenesis and progression.

Methods

The current study involved 54 newly diagnosed patients presenting with CLL as well as 30 normal individuals as controls. After obtaining verbal consent, data collection was done and the blood collected from all enrolled individuals for hematological investigations as well as for molecular categorization of TP53 methylation status. Methylation-specific polymerase chain reaction (MS-PCR) technique was used to define the methylation status of the TP53 gene promoter that encompasses DNA extraction, bisulfite conversion, conventional PCR amplification, running on agarose gel and documentation. Finally, statistical analysis was done to assess any correlation of the TP53 epigenetic alteration to the disease etiology and the progression.

Results

In the current study, all controls and 42 of 54 patients show unmethylated TP53 gene promoter; on the other hand, the methylated promoter was detected among 12 patients with a p-value of 0.001. TP53 gene promoter methylation significantly linked to reduced platelet count (p-value of 0.047) and advanced stage at presentation (p-value of 0.076). No significant differences were seen among both methylated and unmethylated TP53 promoters in relation to the age of the affected individuals, total white blood cell counts and hemoglobin level of the affected individuals.

Conclusion

The current study revealed a significant correlation of TP53 gene promoter methylation to chronic lymphocytic leukemia pathogenesis and lower platelet counts.

Molecular modelling of epitopes recognized by neoplastic B lymphocytes in Chronic Lymphocytic Leukemia

Identification of epitopes recognized by tumour B cells could provide insights into the molecular mechanisms of B cell tumorigenesis through aberrant B cell receptor (BCR) signalling. Here, we analysed the structure of eleven peptides binders of BCRs expressed in Chronic Lymphocytic Leukemia (CLL) patients in order to identify the chemical features required for cross-reactive binding to different CLL clonotypes. Four cross-reactive (CR) and seven no-cross-reactive (NCR) peptides were analysed by means of GRID molecular interaction fields, ligand-based pharmacophore and 3D-QSAR approaches. Based on pharmacophore model, two peptides were generated by specific amino acids substitutions of the parental NCR peptides; these new peptides resumed the common chemical features of CR peptides and bound the CLL BCR clonotypes recognized by CR peptides and parental NCR peptides. Thus, our computational approach guided the pharmacophore modelling of CR peptides. In perspective, peptide binders of CLL BCR clonotypes could represent a powerful tool for computational modelling of epitopes recognized by tumour B cells clones.

The applications of anti-CD20 antibodies to treat various B cells disorders

B-lymphocyte antigen CD20 (called CD20) is known as an activated-glycosylated phosphoprotein which is expressed on the surface of all B-cells. CD20 is involved in the regulation of trans-membrane Ca²⁺ conductance and also play critical roles in cell-cycle progression during human B cell proliferation and activation. The appearance of monoclonal antibody (mAb) technology provided an effective field for targeted therapy in treatment of a variety of diseases such as cancer, and autoimmune diseases. Anti-CD20 is one of important antibodies which could be employed in treatment of several diseases. Increasing evidences revealed that efficacy of different anti-CD20 antibodies is implicated by their function. Hence, evaluation of anti-CD20 antibodies function could provide and introduce new anti-CD20 based therapies. In the present study, we summarized several applications of anti-CD20 antibodies in various immune related disorders including B-CLL (B-cell chronic lymphocytic leukemia), rheumatoid arthritis (RA), multiple sclerosis (MS) and melanoma.

Role and Regulation of Pro-survival BCL-2 Proteins in Multiple Myeloma

Apoptosis plays a key role in protection against genomic instability and maintaining tissue homeostasis, and also shapes humoral immune responses. During generation of an antibody response, multiple rounds of B-cell expansion and selection take place in germinal centers (GC) before high antigen affinity memory B-cells and long-lived plasma cells (PC) are produced. These processes are tightly regulated by the intrinsic apoptosis pathway, and malignant transformation throughout and following the GC reaction is often characterized by apoptosis resistance. Expression of pro-survival BCL-2 family protein MCL-1 is essential for survival of malignant PC in multiple myeloma (MM). In addition, BCL-2 and BCL-XL contribute to apoptosis resistance. MCL-1, BCL-2, and BCL-XL expression is induced and maintained by signals from the bone marrow microenvironment, but overexpression can also result from genetic lesions. Since MM PC depend on these proteins for survival, inhibiting pro-survival BCL-2 proteins using novel and highly specific BH3-mimetic inhibitors is a promising strategy for treatment. This review addresses the role and regulation of pro-survival BCL-2 family proteins during healthy PC differentiation and in MM, as well as their potential as therapeutic targets.

Nanomedicines for the treatment of hematological malignancies

Hematological malignancies (HM) are a collection of malignant transformations originating from cells in the primary or secondary lymphoid organs. Leukemia, lymphoma, and multiple myeloma comprise the three major types of HM. Current treatment consists of bone marrow transplantation, radiotherapy, immunotherapy and chemotherapy. Although, many chemotherapeutic drugs are clinically available for the treatment of HM, the use of these agents is limited due to dose-related toxicity and lack of specificity to tumor tissue. Moreover, the poor pharmacokinetic profile of most of the chemotherapeutics requires high dosage and frequent administration to maintain therapeutic levels at the target site, both increasing adverse effects. This underlines an urgent need for a suitable drug delivery system to improve efficacy, safety, and pharmacokinetic properties of conventional therapeutics. Nanomedicines have proven to enhance these properties for anticancer therapeutics. The most extensively studied nanomedicine systems are lipid-based nanoparticles and polymeric nanoparticles. Typically, nanomedicines are small sub-micron sized particles in the size range of 20-200 nm. The biocompatible and biodegradable nature of nanomedicines makes them attractive vehicles to improve drug delivery. Their small size allows them to extravasate and accumulate at malignant sites passively by means of the enhanced permeability and retention (EPR) effect, resulting from rapid angiogenesis and inflammation. Moreover, the specificity to the target tissue can be further enhanced by surface modification of nanoparticles. This review describes currently available therapies as well as limitations and potential advantages of nanomedicine formulations for treatment of various types of HM. Additionally, recent investigational and approved nanomedicine formulations and their limited applications in HM are discussed.

Bepridil exhibits anti-leukemic activity associated with NOTCH1 pathway inhibition in chronic lymphocytic leukemia

Dysregulated NOTCH1 signaling, by either gene mutations or microenvironment interactions, has been increasingly linked to chronic lymphocytic leukemia (CLL). Thus, inhibiting NOTCH1 activity represents a potential therapeutic opportunity for this disease. Using gene expression-based screening, we identified the calcium channel modulator bepridil as a new NOTCH1 pathway inhibitor. In primary CLL cells, bepridil induced selective apoptosis even in the presence of the protective stroma. Cytotoxic effects of bepridil were independent of NOTCH1 mutation and other prognostic markers. The antitumor efficacy of bepridil was associated with inhibition of NOTCH1 activity through a decrement in trans-membrane and activated NOTCH1 protein levels with unchanged NOTCH2 protein levels. In a CLL xenotransplant model, bepridil significantly reduced the percentage of leukemic cells infiltrating the spleen via enhanced apoptosis and decreased NOTCH1 activation. In conclusion, we report in vitro and in vivo anti-leukemic activity of bepridil associated with inhibition of the NOTCH1 pathway in CLL. These data provide a rationale for the clinical development of bepridil as anti-NOTCH1 targeted therapy for CLL patients.

NOTCH1 Aberrations in Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is an incurable B-cell neoplasm characterized by highly variable clinical outcomes. In recent years, genomic and molecular studies revealed a remarkable heterogeneity in CLL, which mirrored the clinical diversity of this disease. These studies profoundly enhanced our understanding of leukemia cell biology and led to the identification of new biomarkers with potential prognostic and therapeutic significance. Accumulating evidence indicates a key role of deregulated NOTCH1 signaling and NOTCH1 mutations in CLL. This review highlights recent discoveries that improve our understanding of the pathophysiological NOTCH1 signaling in CLL and the clinical impact of NOTCH1 mutations in retrospective and prospective trials. In addition, we discuss the rationale for a therapeutic strategy aiming at inhibiting NOTCH1 signaling in CLL, along with an overview on the currently available NOTCH1-directed approaches.

Identification of new phosphorylation sites of CD23 in B-cells of patients with chronic lymphocytic leukemia

B-cell chronic lymphocytic leukemia (B-CLL) is the most common lymphoproliferative disorder in adults. Patients with B-CLL strongly express the CD23 - C type of lectin (low affinity IgE receptor, Fc epsilon RII), which is linked to B cell activation and proliferation. Phosphorylation in lymphocytes is tightly associated with regulation of protein activities, functional regulation and cell signaling, and may thus affect initiation and/or progression of the disease. Here we report changes in the phosphorylation of CD23 on threonine (pThr314) and two serine residues (pSer254, pSer265) in B lymphocytes of B-CLL patients, using a flow cytometry approach. The majority of tested patients with active forms of B-CLL presented a notable overexpression of CD23 along with pThr314, pSer254, and pSer265 CD23 phosphorylation positivity. Moreover, we have experimentally stimulated the CD23 phosphorylations in a subset of peripheral blood lymphocytes of healthy controls by phorbol-12-myristate-13-acetate treatment. This affects the activation of competent phosphorylation mediating kinases, resulting in the enhanced phosphorylation pattern. Together, these data confirm that CD23 protein is phosphorylated in B cells of B-CLL patients, report the identification of new CD23 phosphorylation sites, and suggest a possible role(s) of such phosphorylations in the activation of CD23 during the process of lymphocytic activation in B-CLL.

Linking SLAMF1 to autophagy and sensitivity to therapy in chronic lymphocytic leukemia

We recently reported that expression of the costimulatory molecule and microbial sensor SLAMF1 (signaling lymphocytic activation molecule family 1, also known as CD150) is lost in chronic lymphocytic leukemia (CLL) patients characterized by a shorter overall survival. SLAMF1 modulates CLL responses to chemokines and regulates autophagy. Loss of SLAMF1 renders CLL cells relatively unresponsive to autophagy-inducing drugs, including B-cell CLL/lymphoma 2 (BCL2) inhibitors.

Therapeutic inhibition of USP7-PTEN network in chronic lymphocytic leukemia: a strategy to overcome TP53 mutated/deleted clones

Chronic Lymphocytic Leukemia (CLL) is a lymphoproliferative disorder with either indolent or aggressive clinical course. Current treatment regiments have significantly improved the overall outcomes even if higher risk subgroups - those harboring TP53 mutations or deletions of the short arm of chromosome 17 (del17p) - remain highly challenging. In the present work, we identified USP7, a known de-ubiquitinase with multiple roles in cellular homeostasis, as a potential therapeutic target in CLL. We demonstrated that in primary CLL samples and in CLL cell lines USP7 is: i) over-expressed through a mechanism involving miR-338-3p and miR-181b deregulation; ii) functionally activated by Casein Kinase 2 (CK2), an upstream interactor known to be deregulated in CLL; iii) effectively targeted by the USP7 inhibitor P5091. Treatment of primary CLL samples and cell lines with P5091 induces cell growth arrest and apoptosis, through the restoration of PTEN nuclear pool, both in TP53-wild type and -null environment. Importantly, PTEN acts as the main tumor suppressive mediator along the USP7-PTEN axis in a p53 dispensable manner. In conclusion, we propose USP7 as a new druggable target in CLL.

Elevated levels of follicular T helper cells and their association with therapeutic effects in patients with chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is characterized by an abnormal expansion of mature B cells with variable progression. Follicular T helper (Tfh) cells help B cells differentiate into plasma cells or long-lived memory B cells in germinal centres (GCs). However, the role of Tfh cells in CLL is poorly understand, and whether it plays a critical role in disease progression in vivo is lacking. In this study, we investigate the dynamic change of circulating Tfh cells in peripheral blood from patients with CLL during the treatment periods to evaluate their utility to predict disease progression. Our findings revealed the expansion of circulating CD4⁺CXCR5⁺, CD4⁺ICOS⁺, CD4⁺PD-1⁺ and CD4⁺CXCR5⁺ICOS⁺PD-1⁺ (Tfh) cells but lower serum IL-21 levels and CD4⁺ T cell polarization not only to Tfh2 subtypes but also to Tfh17 subtypes in patients with CLL at pretreatment compared to patients with monoclonal B cell lymphocytosis (MBL) and healthy individuals, especially in those with advanced stage, which indicate these Tfh cells could be employed as a novel indicator for disease progression. Moreover, we observed significant correlations of Tfh17 and immunoglobulin heavy chain variable region (IGHV) mutation. Importantly, significantly decreased CD4⁺ICOS⁺, CD4⁺PD-1⁺ and Tfh cells were found after effective treatments, whereas a significantly high CD4⁺ICOS⁺, CD4⁺PD-1⁺ and Tfh cells were still found in those with progressive disease after treatments, suggesting that circulating CD4⁺ICOS⁺, CD4⁺PD-1⁺, Tfh cells could predict therapeutic effects.

Gene expression profile induced by arsenic trioxide in chronic lymphocytic leukemia cells reveals a central role for heme oxygenase-1 in apoptosis and regulation of matrix metalloproteinase-9

CLL remains an incurable disease in spite of the many new compounds being tested. Arsenic trioxide (ATO) induces apoptosis in all CLL cell types and could constitute an efficient therapy. To further explore this, we have studied the gene expression profile induced by ATO in CLL cells. ATO modulated many genes, largely involved in oxidative stress, being HMOX1 the most upregulated gene, also induced at the protein level. ATO also increased MMP-9, as we previously observed, both at the mRNA and protein level. Using specific inhibitors, qPCR analyses, and gene silencing approaches we demonstrate that upregulation of MMP-9 by ATO involved activation of the p38 MAPK/AP-1 signaling pathway. Moreover, gene silencing HMOX1 or inhibiting HMOX1 activity enhanced p38 MAPK phosphorylation and c-jun expression/activation, resulting in transcriptional upregulation of MMP-9. Overexpression of HMOX1 or enhancement of its activity, had the opposite effect. Cell viability analyses upon modulation of HMOX1 expression or activity demonstrated that HMOX1 had a pro-apoptotic role and enhanced the cytotoxic effect of ATO in CLL cells. We have therefore identified a new mechanism in which HMOX1 plays a central role in the response of CLL cells to ATO and in the regulation of the anti-apoptotic protein MMP-9. Thus, HMOX1 arises as a new therapeutic target in CLL and the combination of HMOX1 modulators with ATO may constitute an efficient therapeutic strategy in CLL.

Long non-coding RNAs in normal and malignant hematopoiesis

Long non-coding RNAs (lncRNAs) are defined as ncRNAs of more than 200 nt in length. They are involved in a large spectrum of biological processes, such as maintenance of genome integrity, genomic imprinting, cell differentiation, and development by means of mechanisms that remain to be fully elucidated. Besides their role in normal cellular physiology, accumulating evidence has linked lncRNA expression and functions to cancer development and progression. In this review, we summarize and discuss what is known about their expression and roles in hematopoiesis with a particular focus on their cell-type specificity, functional interactions, and involvement in the pathobiology of hematological malignancies.

Coexistence of t(2;14;11)(p16.1;q32;q23) and t(14;19)(q32;q13.3) chromosome translocations in a patient with chronic lymphocytic leukemia: A case report

RATIONALE

With combination of multiple techniques, we have successfully characterized unique, complex chromosomal changes in a patient with chronic lymphocytic leukemia (CLL), a lymphoproliferative disorder.

DIAGNOSES

The diagnosis was based on white blood cell, flow cytometry, and immunophenotypes and confirmed by karyotype, fluorescence in situ hybridization, and array comparative genomic hybridization from the patient's blood culture.

INTERVENTIONS

The patient was given fludarabine, cyclophosphamide and rituximab (FCR) for 6 cycles.

OUTCOMES

After completion of 6 cycles of FCR, the computed tomography scans of the neck/chest/abdomen/pelvic showed that the patient in CR. During the 10-month follow-up, the patient's clinical course remained uneventful.

LESSONS

The translocation t(14;19) identified in this patient is a recurrent translocation found in patients with chronic B-cell lymphoproliferative disorders and the 3-way translocation involving chromosomes 2, 14, and 11 may play a role as an enhancer.

Microenvironmental stromal cells abrogate NF-κB inhibitor-induced apoptosis in chronic lymphocytic leukemia

Nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) is known to play an important role in the pathogenesis of chronic lymphocytic leukemia (CLL). Several NF-κB inhibitors were shown to successfully induce apoptosis of CLL cells in vitro Since the microenvironment is known to be crucial for the survival of CLL cells, herein, we tested whether NF-κB inhibition may still induce apoptosis in these leukemic cells in the presence of protective stromal interaction. We used the specific NF-κB inhibitor dehydroxymethylepoxyquinomicin (DHMEQ). Microenvironmental support was mimicked by co-culturing CLL cells with bone marrow-derived stromal cell lines (HS-5 and M2-10B4). NF-κB inhibition by DHMEQ in CLL cells could be confirmed in both the monoculture and co-culture setting. In line with previous reports, NF-κB inhibition induced apoptosis in the monoculture setting by activating the intrinsic apoptotic pathway resulting in poly (ADP-ribose) polymerase (PARP)-cleavage; however, it was unable to induce apoptosis in leukemic cells co-cultured with stromal cells. Similarly, small interfering ribonucleic acid (siRNA)-mediated RELA downregulation induced apoptosis of CLL cells cultured alone, but not in the presence of supportive stromal cells. B-cell activating factor (BAFF) was identified as a microenvironmental messenger potentially protecting the leukemic cells from NF-κB inhibition-induced apoptosis. Finally, we show improved sensitivity of stroma-supported CLL cells to NF-κB inhibition when combining the NF-κB inhibitor with the SYK inhibitor R406 or the Bruton's tyrosine kinase (BTK) inhibitor ibrutinib, agents known to inhibit the stroma-leukemia crosstalk. We conclude that NF-κB inhibitors are not promising as monotherapies in CLL, but may represent attractive therapeutic partners for ibrutinib and R406.

Early stages in the ontogeny of small B-cell lymphomas: genetics and microenvironment

In this review, we focus on the mechanisms underlying lymphomagenesis in chronic lymphocytic leukaemia, follicular lymphoma, mantle cell lymphoma and splenic marginal zone lymphoma. The cells of origin of these small B-cell lymphomas are distinct, as are the characteristic chromosomal lesions and clinical courses. One shared feature is retention of expression of surface immunoglobulin. Analysis of this critical receptor reveals the point of differentiation reached by the cell of origin. Additionally, the sequence patterns of the immunoglobulin-variable domains can indicate a role for stimulants of the B-cell receptor before, during and after malignant transformation. The pathways driven via the B-cell receptor are now being targeted by specific kinase inhibitors with exciting clinical effects. To consider routes to pathogenesis, potentially offering earlier intervention, or to identify causative factors, genetic tools are being used to track pretransformation events and the early phases in lymphomagenesis. These methods are revealing that chromosomal changes are only one of the many steps involved, and that the influence of surrounding cells, probably multiple and variable according to tissue location, is required, both to establish tumours and to maintain growth and survival. Similarly, the influence of the tumour microenvironment may protect malignant cells from eradication by treatment, and the resulting minimal residual disease will eventually give rise to relapse. The common and different features of the four lymphomas will be summarized to show how normal B lymphocytes can be subverted to generate tumours, how these tumours evolve and how their weaknesses can be attacked by targeted therapies.

Emerging role of BCR signaling inhibitors in immunomodulation of chronic lymphocytic leukemia

Approved therapies that target the B-cell receptor (BCR) signaling pathway, such as ibrutinib and idelalisib, are known to show activity in chronic lymphocytic leukemia (CLL) via their direct effects on crucial survival pathways in malignant B cells. However, these therapies also have effects on T cells in CLL by mediating toxicity and possibly controlling disease. By focusing on the effects of BCR signaling inhibitors on the T-cell compartment, we may gain new insights into the comprehensive biological outcomes of systemic treatment to further understand mechanisms of drug efficacy, predict the toxicity or adverse events, and identify novel combinatorial therapies. Here, we review T-cell abnormalities in preclinical models and patient samples, finding that CLL T cells orchestrate immune dysfunction and immune-related complications. We then continue to address the effects of clinically available small molecule BCR signaling inhibitors on the immune cells, especially T cells, in the context of concomitant immune-mediated adverse events and implications for future treatment strategies. Our review suggests potentially novel mechanisms of action related to BCR inhibitors, providing a rationale to extend their use to other cancers and autoimmune disorders.

Cost-effectiveness of kinase inhibitors for hematologic malignancies: a systematic and critical review

INTRODUCTION

Several genetic disruptions lead to constitutive activation of those kinases leukemic cells depend on for survival and proliferation. Kinase inhibitors (KI) are major therapeutic innovations for chronic myeloid leukemia (CML), chronic lymphoid leukemia (CLL) and myelofibrosis (MF) providing a relevant improvement of quality-adjusted survival in patients with high-risk or refractory disease. CML patients are being treated with first-generation KI imatinib since many years, achieving expected survivals longer than 10 years. Second- and third generations KIs, such as nilotinib, dasatinib, ponatinib and bosutinib, recently expanded the therapeutic yield for CML and treatment discontinuation in patients with persistent deep molecular response is being pursued. Areas covered: This review summarizes available evidence on economic analyses of KI treatments for CML, CLL and MF aimed at identifying the key determinants of KI cost-effectiveness. Expert commentary: On converse, specific KIs for CLL and MF patients have been marketed only in the last few years. Ibrutinib and idelalisib allowed to improve the outcomes of relapsed/refractory CLL and of patients with poor genetic features, while the first-in-class JAK2 inhibitor ruxolitinib allowed to improve symptoms of advanced MF patients and to prolong survival in responders. In the current situation of healthcare budget restrictions worldwide, the value for cost of the above KIs has been questioned.

Toll-like receptor 9 stimulation can induce IκBζ expression and IgM secretion in chronic lymphocytic leukemia cells

Chronic lymphocytic leukemia cells strongly depend on external stimuli for their survival. Both antigen receptor and co-stimulatory receptors, including Toll-like receptors, can modulate viability and proliferation of leukemic cells. Toll-like receptor ligands, and particularly the TLR9 ligand CpG, mediate heterogeneous responses in patients' samples reflecting the clinical course of the subjects. However, the molecular framework of the key signaling events underlying such heterogeneity is undefined. We focused our studies on a subset of chronic lymphocytic leukemia cases characterized by expression of CD38 and unmutated immunoglobulin genes, who respond to CpG with enhanced metabolic cell activity. We report that, while CpG induces NFKBIZ mRNA in all the samples analyzed, it induces the IκBζ protein in a selected group of cases, through an unanticipated post-transcriptional mechanism. Interestingly, IκBζ plays a causal role in sustaining CpG-induced cell viability and chemoresistance, and CpG stimulation can unleash immunoglobulin secretion by IκBζ-positive malignant cells. These results identify and characterize IκBζ as a marker and effector molecule of distinct key pathways in chronic lymphocytic leukemia.

Long non-coding RNAs in B-cell malignancies: a comprehensive overview

B-cell malignancies constitute a large part of hematological neoplasias. They represent a heterogeneous group of diseases, including Hodgkin's lymphoma, most non-Hodgkin's lymphomas (NHL), some leukemias and myelomas. B-cell malignancies reflect defined stages of normal B-cell differentiation and this represents the major basis for their classification. Long non-coding RNAs (lncRNAs) are non-protein-coding transcripts longer than 200 nucleotides, for which many recent studies have demonstrated a function in regulating gene expression, cell biology and carcinogenesis. Deregulated expression levels of lncRNAs have been observed in various types of cancers including hematological malignancies. The involvement of lncRNAs in cancer initiation and progression and their attractive features both as biomarker and for therapeutic research are becoming increasingly evident. In this review, we summarize the recent literature to highlight the status of the knowledge of lncRNAs role in normal B-cell development and in the pathogenesis of B-cell tumors.

High-resolution melting analysis for rapid and sensitive NOTCH1 screening in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a biological and clinical heterogeneous disease. Activating mutations of NOTCH1 have been implicated to be associated with adverse prognosis in CLL. The objective of the present study was to develop an effective high-resolution melting (HRM) assay for detecting NOTCH1 mutations. Genomic DNA (gDNA) extracted from 133 CLL patients was screened by HRM assay, and the results were compared with the data obtained using direct sequencing. The relative sensitivity of the HRM assay and direct sequencing was evaluated using diluted gDNA with different NOTCH1 mutational frequencies. The HRM assay was able to detect and discriminate samples with NOTCH1 mutations from the wild-type template in CLL. Eight of the 133 CLL patients (6.02%) were scored positively for NOTCH1 mutations in the HRM assay. The results of the NOTCH1 mutations detected by HRM analysis achieved 100% concordance with those determined from direct sequencing. HRM had a higher sensitivity (1%) and shorter turn-around time (TAT), compared to direct sequencing. In conclusion, the HRM assay developed by us was confirmed to be a rapid, sensitive, and promising approach for high-throughput prognostic NOTCH1 screening in CLL. It enables real-time NOTCH1 evaluation, which is of great significance in clinical practice and may facilitate the decision-making of clinicians in CLL.

CD69 expression potentially predicts response to bendamustine and its modulation by ibrutinib or idelalisib enhances cytotoxic effect in chronic lymphocytic leukemia

Clinical responses to bendamustine in chronic lymphocytic leukemia (CLL) are highly heterogeneous and no specific markers to predict sensitivity to this drug have been reported. In order to identify biomarkers of response, we analyzed the in vitro activity of bendamustine and the gene expression profile in primary CLL cells. We observed that mRNA expression of CD69 (CD69) and ITGAM (CD11b) constitute the most powerful predictor of response to bendamustine. When we interrogated the predictive value of the corresponding cell surface proteins, the expression of the activation marker CD69 was the most reliable predictor of sensitivity to bendamustine. Importantly, a multivariate analysis revealed that the predictive value of CD69 expression was independent from other clinico-biological CLL features. We also showed that when CLL cells were co-cultured with distinct subtypes of stromal cells, an upregulation of CD69 was accompanied by a reduced sensitivity to bendamustine. In agreement with this, tumor cells derived from lymphoid tumor niches harbored higher CD69 expression and were less sensitive to bendamustine than their peripheral blood counterparts. Furthermore, pretreatment of CD69 ^high CLL cases with the B-cell receptor (BCR) pathway inhibitors ibrutinib and idelalisib decreased CD69 levels and enhanced bendamustine cytotoxic effect. Collectively, our findings indicate that CD69 could be a predictor of bendamustine response in CLL patients and the combination of clinically-tested BCR signaling inhibitors with bendamustine may represent a promising strategy for bendamustine low responsive CLL cases.

Identifying High-Risk Chronic Lymphocytic Leukemia: A Pathogenesis-Oriented Appraisal of Prognostic and Predictive Factors in Patients Treated with Chemotherapy with or without Immunotherapy

Chronic lymphocytic leukemia (CLL) displays an extremely variable clinical behaviour. Accurate prognostication and prediction of response to treatment are important in an era of effective first-line regimens and novel molecules for high risk patients. Because a plethora of prognostic biomarkers were identified, but few of them were validated by multivariable analysis in comprehensive prospective studies, we applied in this survey stringent criteria to select papers from the literature in order to identify the most reproducible prognostic/predictive markers. Each biomarker was analysed in terms of reproducibility across the different studies with respect to its impact on time to first treatment (TTFT), progression free survival (PFS), overall survival (OS) and response to treatment. We were able to identify the following biomarkers as the most reliable in guiding risk stratification in the daily clinical practice: 17p-/TP53 mutations, IGHV unmutated configuration, short telomeres and 11q-. However, the method for measuring telomere length was not validated yet and 11q- was predictive of inferior OS only in those patients who did not receive FCR-like combinations. Stage and lymphocytosis were predictive of shorter TTFT and age, high serum thymidine kinase levels and poor performance status were predictive of shorter OS. Using our criteria no parameter was found to independently predict for inferior response to treatment.

Bone marrow stroma-induced resistance of chronic lymphocytic leukemia cells to arsenic trioxide involves Mcl-1 upregulation and is overcome by inhibiting the PI3Kδ or PKCβ signaling pathways

CLL remains an incurable disease in spite of the many new compounds being studied. Arsenic trioxide (ATO) induces apoptosis in all CLL cell types and could constitute an efficient therapy. To further explore this, we have studied the influence of stromal cells, key components of the CLL microenvironment, on the response of CLL cells to ATO. Bone marrow stromal cells induced CLL cell resistance to 2 μM ATO and led to activation of Lyn, ERK, PI3K and PKC, as well as NF-κB and STAT3. Mcl-1, Bcl-xL, and Bfl-1 were also upregulated after the co-culture. Inhibition experiments indicated that PI3K and PKC were involved in the resistance to ATO induced by stroma. Moreover, idelalisib and sotrastaurin, specific inhibitors for PI3Kδ and PKCβ, respectively, inhibited Akt phosphorylation, NF-κB/STAT3 activation and Mcl-1 upregulation, and rendered cells sensitive to ATO. Mcl-1 was central to the mechanism of resistance to ATO, since: 1) Mcl-1 levels correlated with the CLL cell response to ATO, and 2) blocking Mcl-1 expression or function with specific siRNAs or inhibitors overcame the protecting effect of stroma. We have therefore identified the mechanism involved in the CLL cell resistance to ATO induced by bone marrow stroma and show that idelalisib or sotrastaurin block this mechanism and restore sensibility to ATO. Combination of ATO with these inhibitors may thus constitute an efficient treatment for CLL.

lncRNA profiling in early-stage chronic lymphocytic leukemia identifies transcriptional fingerprints with relevance in clinical outcome

Long non-coding RNAs (lncRNAs) represent a novel class of functional RNA molecules with an important emerging role in cancer. To elucidate their potential pathogenetic role in chronic lymphocytic leukemia (CLL), a biologically and clinically heterogeneous neoplasia, we investigated lncRNAs expression in a prospective series of 217 early-stage Binet A CLL patients and 26 different subpopulations of normal B-cells, through a custom annotation pipeline of microarray data. Our study identified a 24-lncRNA-signature specifically deregulated in CLL compared with the normal B-cell counterpart. Importantly, this classifier was validated on an independent data set of CLL samples. Belonging to the lncRNA signature characterizing distinct molecular CLL subgroups, we identified lncRNAs recurrently associated with adverse prognostic markers, such as unmutated IGHV status, CD38 expression, 11q and 17p deletions, and NOTCH1 mutations. In addition, correlation analyses predicted a putative lncRNAs interplay with genes and miRNAs expression. Finally, we generated a 2-lncRNA independent risk model, based on lnc-IRF2-3 and lnc-KIAA1755-4 expression, able to distinguish three different prognostic groups in our series of early-stage patients. Overall, our study provides an important resource for future studies on the functions of lncRNAs in CLL, and contributes to the discovery of novel molecular markers with clinical relevance associated with the disease.

A new phosphorylated form of Ku70 identified in resistant leukemic cells confers fast but unfaithful DNA repair in cancer cell lines

Ku70-dependent canonical nonhomologous end-joining (c-NHEJ) DNA repair system is fundamental to the genome maintenance and B-cell lineage. c-NHEJ is upregulated and error-prone in incurable forms of chronic lymphocytic leukemia which also displays telomere dysfunction, multiple chromosomal aberrations and the resistance to DNA damage-induced apoptosis. We identify in these cells a novel DNA damage inducible form of phospho-Ku70. In vitro in different cancer cell lines, Ku70 phosphorylation occurs in a heterodimer Ku70/Ku80 complex within minutes of genotoxic stress, necessitating its interaction with DNA damage-induced kinase pS2056-DNA-PKcs and/or pS1981-ATM. The mutagenic effects of phospho-Ku70 are documented by a defective S/G2 checkpoint, accelerated disappearance of γ-H2AX foci and kinetics of DNA repair resulting in an increased level of genotoxic stress-induced chromosomal aberrations. Together, these data unveil an involvement of phospho-Ku70 in fast but inaccurate DNA repair; a new paradigm linked to both the deregulation of c-NHEJ and the resistance of malignant cells.

Surface IgM expression and function are associated with clinical behavior, genetic abnormalities, and DNA methylation in CLL

High sIgM level is a potential key factor associated with poorer clinical outcome in CLL. Genetic and epigenetic features influence sIgM levels and function in CLL.

Key Molecular Drivers of Chronic Lymphocytic Leukemia

Chronic lymphocytic leukemia (CLL) is an adult neoplastic disease of B cells characterized by variable clinical outcomes. Although some patients have an aggressive form of the disease and often encounter treatment failure and short survival, others have more stable disease with long-term survival and little or no need for theraphy. In the past decade, significant advances have been made in our understanding of the molecular drivers that affect the natural pathology of CLL. The present review describes what is known about these key molecules in the context of their role in tumor pathogenicity, prognosis, and therapy.

The splicing modulator sudemycin induces a specific antitumor response and cooperates with ibrutinib in chronic lymphocytic leukemia

Mutations or deregulated expression of the components of the spliceosome can influence the splicing pattern of several genes and contribute to the development of tumors. In this context, we report that the spliceosome modulator sudemycin induces selective cytotoxicity in primary chronic lymphocytic leukemia (CLL) cells when compared with healthy lymphocytes and tumor cells from other B-lymphoid malignancies, with a slight bias for CLL cases with mutations in spliceosome-RNA processing machinery. Consistently, sudemycin exhibits considerable antitumor activity in NOD/SCID/IL2Rγ−/− (NSG) mice engrafted with primary cells from CLL patients. The antileukemic effect of sudemycin involves the splicing modulation of several target genes important for tumor survival, both in SF3B1-mutated and -unmutated cases. Thus, the apoptosis induced by this compound is related to the alternative splicing switch of MCL1 toward its proapoptotic isoform. Sudemycin also functionally disturbs NF-κB pathway in parallel with the induction of a spliced RELA variant that loses its DNA binding domain. Importantly, we show an enhanced antitumor effect of sudemycin in combination with ibrutinib that might be related to the modulation of the alternative splicing of the inhibitor of Btk (IBTK). In conclusion, we provide first evidence that the spliceosome is a relevant therapeutic target in CLL, supporting the use of splicing modulators alone or in combination with ibrutinib as a promising approach for the treatment of CLL patients.