Exploiting biological diversity and genomic aberrations in chronic lymphocytic leukemia

Chronic Lymphocytic Leukemia: 2025 Update on the Epidemiology, Pathogenesis, Diagnosis, and Therapy

DISEASE OVERVIEW

Chronic lymphocytic leukemia (CLL) is the most frequent type of leukemia. It typically occurs in older patients and has a highly variable clinical course. Leukemic transformation is initiated by specific genomic alterations that interfere with the regulation of proliferation and apoptosis in clonal B-cells.

DIAGNOSIS

The diagnosis is established by blood counts, blood smears, and immunophenotyping of circulating B-lymphocytes, which identify a clonal B-cell population carrying the CD5 antigen as well as typical B-cell markers.

PROGNOSIS AND STAGING

Two clinical staging systems, Rai and Binet, provide prognostic information by using the results of physical examination and blood counts. Various biological and genetic markers provide additional prognostic information. Deletions of the short arm of chromosome 17 (del(17p)) and/or mutations of the TP53 gene predict a shorter time to progression with most targeted therapies. The CLL international prognostic index (CLL-IPI) integrates genetic, biological, and clinical variables to identify distinct risk groups of patients with CLL. The CLL-IPI retains its significance in the era of targeted agents, but the overall prognosis of CLL patients with high-risk stages has improved.

THERAPY

Only patients with active or symptomatic disease or with advanced Binet or Rai stages require therapy. When treatment is indicated, several therapeutic options exist: combinations of the BCL2 inhibitor venetoclax with obinutuzumab, or venetoclax with ibrutinib, or monotherapy with one of the inhibitors of Bruton tyrosine kinase (BTK). At relapse, the initial treatment may be repeated if the treatment-free interval exceeds 3 years. If the leukemia relapses earlier, therapy should be changed using an alternative regimen.

FUTURE CHALLENGES

Combinations of targeted agents now provide efficient therapies with a fixed duration that generate deep and durable remissions. These fixed-duration therapies have gained territory in the management of CLL, as they are cost-effective, avoid the emergence of resistance, and offer treatment free time to the patient. The cure rate of these novel combination regimens is unknown. Moreover, the optimal sequencing of targeted therapies remains to be determined. A medical challenge is to treat patients who are double-refractory to both BTK and BCL2 inhibitors. These patients need to be treated within experimental protocols using novel drugs.

Utilizing risk factors to guide treatment decisions in chronic lymphocytic leukemia

INTRODUCTION

In the era of chemo-immunotherapy, high-risk factors unequivocally predicted inferior outcomes for patients with CLL. The widespread adoption of BTK inhibitors has challenged the practical implications of such testing, as many patients have improved outcomes despite the presence of high-risk features. The impact of adverse prognostic factors, such as unmutated IGHV, on survival has been ameliorated by continuous treatment with BTK inhibitors, but not by finite-duration therapy with venetoclax-based combinations. Furthermore, TP53 abnormalities continue to be associated with worse outcomes in the era of novel agents. New treatment modalities, such as pirtobrutinib, lisocabtagene maraleucel, and ongoing studies combining BTK inhibitors with venetoclax, raise new questions on the significance of prognostic factors of survival for patients with CLL.

AREAS COVERED

Herein, we summarized the available literature on patients with CLL harboring high-risk biomarkers, with a focus on data from key clinical trials.

EXPERT OPINION

Testing for prognostic biomarkers will remain relevant to identify patients who may have increased benefit from novel therapeutic strategies, such as combination therapies and novel agents. Patients with high-risk disease should be encouraged to participate in clinical trials.

Circular RNA as a Biomarker for Diagnosis, Prognosis and Therapeutic Target in Acute and Chronic Lymphoid Leukemia

Circular RNAs (circRNAs) are single-stranded RNAs that have received much attention in recent years. CircRNAs lack a 5' head and a 3' poly-A tail. The structure of this type of RNAs make them resistant to digestion by exonucleases. CircRNAs are expressed in different cells and have various functions. The function of circRNAs is done by sponging miRNAs, changing gene expression, and protein production. The expression of circRNAs changes in different types of cancers, which causes changes in cell growth, proliferation, differentiation, and apoptosis. Changes in the expression of circRNAs can cause the invasion and progression of tumors. Studies have shown that changes in the expression of circRNAs can be seen in acute lymphoid leukemia (ALL) and chronic lymphoid leukemia (CLL). The conducted studies aim to identify circRNAs whose expression has changed in these leukemias and their more precise function so that these circRNAs can be identified as biomarkers, prediction of patient prognosis, and treatment targets for ALL and CLL patients. In this study, we review the studies conducted on the role and function of circRNAs in ALL and CLL patients. The results of the studies show that there is a possibility of using circRNAs as biomarkers in the identification and treatment of patients in the future.

GLP and G9a histone methyltransferases as potential therapeutic targets for lymphoid neoplasms

Histone methyltransferases (HMTs) are enzymes that regulate histone methylation and play an important role in controlling transcription by altering the chromatin structure. Aberrant activation of HMTs has been widely reported in certain types of neoplastic cells. Among them, G9a/EHMT2 and GLP/EHMT1 are crucial for H3K9 methylation, and their dysregulation has been associated with tumor initiation and progression in different types of cancer. More recently, it has been shown that G9a and GLP appear to play a critical role in several lymphoid hematologic malignancies. Importantly, the key roles played by both enzymes in various diseases made them attractive targets for drug development. In fact, in recent years, several groups have tried to develop small molecule inhibitors targeting their epigenetic activities as potential anticancer therapeutic tools. In this review, we discuss the physiological role of GLP and G9a, their oncogenic functions in hematologic malignancies of the lymphoid lineage, and the therapeutic potential of epigenetic drugs targeting G9a/GLP for cancer treatment.

An overview of prognostic markers in patients with CLL

Chronic lymphocytic leukemia (CLL) is a low-grade B-cell lymphoproliferative disorder. It is the most prevalent type of leukemia in the western countries, with a median age at diagnosis of 70 years. In 2023, it is estimated that there will be 18,740 new cases of CLL, and an estimated 4,490 people will die of this disease. It represents 1.0% of all new cancer cases in the U.S. The rate of new cases was 4.6 per 100,000 men and women per year based on 2016-2020 cases, age-adjusted. Death rates from CLL are higher among older adults, or those 75 and older. The death rate was 1.1 per 100,000 men and women per year based on 2016-2020 deaths, age-adjusted. A common question that patients with CLL ask during their first clinic visit is: "How long will it be before I would need treatment?" Although this might seem like a simple question, the answer is not straight forward. CLL is a heterogenous disease, with a variable clinical course. Some patients may present with an aggressive disease requiring early initiation of treatment, while others have an indolent course and some, having so called smoldering CLL, may never need treatment. The variability in disease course can make predicting disease prognosis a complicated process. This brings forth the importance of establishing prognostic models that can predict disease course, time to treatment, and survival outcomes in such a heterogenous disease. The Rai and Binet staging systems were developed in the late 1970s to early 1980s. They separated patients into different stages based on clinical characteristics and laboratory findings. These simple staging systems are still in use; however, several prognostic markers need to be added for an individualized assessment and, with the recent development of genomic techniques leading to better understanding of CLL at the molecular level, newer prognostic markers have emerged.

Potential New Therapies "ROS-Based" in CLL: An Innovative Paradigm in the Induction of Tumor Cell Apoptosis

Chronic lymphocytic leukemia, in spite of recent advancements, is still an incurable disease; the majority of patients eventually acquire resistance to treatment through relapses. In all subtypes of chronic lymphocytic leukemia, the disruption of normal B-cell homeostasis is thought to be mostly caused by the absence of apoptosis. Consequently, apoptosis induction is crucial to the management of this illness. Damaged biological components can accumulate as a result of the oxidation of intracellular lipids, proteins, and DNA by reactive oxygen species. It is possible that cancer cells are more susceptible to apoptosis because of their increased production of reactive oxygen species. An excess of reactive oxygen species can lead to oxidative stress, which can harm biological elements like DNA and trigger apoptotic pathways that cause planned cell death. In order to upset the balance of oxidative stress in cells, recent therapeutic treatments in chronic lymphocytic leukemia have focused on either producing reactive oxygen species or inhibiting it. Examples include targets created in the field of nanomedicine, natural extracts and nutraceuticals, tailored therapy using biomarkers, and metabolic targets. Current developments in the complex connection between apoptosis, particularly ferroptosis and its involvement in epigenomics and alterations, have created a new paradigm.

An effective treatment and suspicious adverse reaction to Ibrutinib in a patient diagnosed with splenic B-cell lymphoma/leukaemia with prominent nucleoli: A first case report

RATIONALE

Splenic B-cell lymphoma/leukemia with prominent nucleoli (SBLPN) is a new classification, which is so rare that it lacks clinical data.

PATIENT CONCERNS

An increased proportion of prolymphocytes (84%) in the bone marrow smear. Whole exon sequence analysis revealed a TP53 mutation.

DIAGNOSES

Combining the clinical features with laboratory test results led to a diagnosis of SBLPN which was made according to the 5th edition of the WHO classification of hematolymphoid tumors, although the patient was diagnosed with B-PLL when guided by the 4th edition of the WHO classification.

INTERVENTIONS

The use of Ibrutinib as an effective treatment.

OUTCOMES

The patient was in complete remission after 5 months of Ibrutinib and then died of sudden aortic dissection.

LESSONS

Ibrutinib was an effective regimen for SBLPN. Aortic dissection might be considered as a suspicious adverse reaction to Ibrutinib.

Prognostication of DNA Damage Response Protein Expression Patterns in Chronic Lymphocytic Leukemia

Proteomic DNA Damage Repair (DDR) expression patterns in Chronic Lymphocytic Leukemia were characterized by quantifying and clustering 24 total and phosphorylated DDR proteins. Overall, three protein expression patterns (C1-C3) were identified and were associated as an independent predictor of distinct patient overall survival outcomes. Patients within clusters C1 and C2 had poorer survival outcomes and responses to fludarabine, cyclophosphamide, and rituxan chemotherapy compared to patients within cluster C3. However, DDR protein expression patterns were not prognostic in more modern therapies with BCL2 inhibitors or a BTK/PI3K inhibitor. Individually, nine of the DDR proteins were prognostic for predicting overall survival and/or time to first treatment. When looking for other proteins that may be associated with or influenced by DDR expression patterns, our differential expression analysis found that cell cycle and adhesion proteins were lower in clusters compared to normal CD19 controls. In addition, cluster C3 had a lower expression of MAPK proteins compared to the poor prognostic patient clusters thus implying a potential regulatory connection between adhesion, cell cycle, MAPK, and DDR signaling in CLL. Thus, assessing the proteomic expression of DNA damage proteins in CLL provided novel insights for deciphering influences on patient outcomes and expanded our understanding of the potential complexities and effects of DDR cell signaling.

Genetic Testing at Diagnosis Has Prognostic Value in Patients with Chronic Lymphocytic Leukemia including at Early Stages

Chronic lymphocytic leukemia (CLL) has a variable clinical evolution, with some patients living treatment-free for decades while others require therapy shortly after diagnosis. In a consecutive series of 217 CLL patients, molecular biomarkers with prognostic value (IGHV status, TP53 mutations, and cytogenetics), whose analysis is recommended prior to treatment start, were studied at diagnosis. Multivariate analyses identified prognostic variables for overall survival (OS) and time to first treatment (TTFT) and validated the CLL-IPI and IPS-E variables for all or early-stage patients (Rai 0–2/Binet A), respectively. Unmutated IGHV was associated with shorter OS and TTFT, even for early-stage patients. Lymphocyte count was not statistically significant for TTFT of early-stage patients in multivariate analysis. Our results validate the prognostic value of IGHV mutational status at diagnosis for OS and TTFT, including for early stages. Our findings suggest a role for molecular and mutational analysis at diagnosis in future prospective studies.

Chronic lymphocytic leukemia: 2022 update on diagnostic and therapeutic procedures

DISEASE OVERVIEW

Chronic lymphocytic leukemia (CLL) is one of the most frequent types of leukemia. It typically occurs in elderly patients and has a highly variable clinical course. Leukemic transformation is initiated by specific genomic alterations that interfere with the regulation of proliferation and of apoptosis in clonal B-cells.

DIAGNOSIS

The diagnosis is established by blood counts, blood smears, and immunophenotyping of circulating B-lymphocytes, which identify a clonal B-cell population carrying the CD5 antigen as well as typical B-cell markers.

PROGNOSIS AND STAGING

The clinical staging systems provide prognostic information by using the results of physical examination and blood counts. Various biological and genetic markers provide additional prognostic information. Deletions of the short arm of chromosome 17 (del[17p]) and/or mutations of the TP53 gene predict resistance to chemoimmunotherapy and a shorter time to progression with most targeted therapies. The CLL international prognostic index integrates genetic, biological, and clinical variables to identify distinct risk groups of patients with CLL.

THERAPY

Only patients with active or symptomatic disease or with advanced Binet or Rai stages require therapy. When treatment is indicated, several therapeutic options exist: a combination of the B-cell lymphoma 2 (BCL2) inhibitor venetoclax with obinutuzumab, monotherapy with inhibitors of Bruton tyrosine kinase (BTK) such as ibrutinib and acalabrutinib, or chemoimmunotherapy. At relapse, the initial treatment may be repeated, if the treatment-free interval exceeds 3 years. If the disease relapses earlier, therapy should be changed using an alternative regimen. Patients with a del(17p) or TP53 mutation are usually resistant to chemotherapy and should, therefore, be treated with targeted agents.

FUTURE CHALLENGES

Combinations of targeted agents are now being investigated to create efficient, potentially curative therapies of CLL with fixed duration. One of the most relevant questions currently addressed in clinical trials is the comparison of monotherapies with BTK inhibitors with fixed duration combination therapies. Moreover, the optimal sequencing of targeted therapies remains to be determined. Alternative therapies are needed for patients with BTK and BCL2 inhibitor double-refractory disease.

Therapeutic Options for Patients with TP53 Deficient Chronic Lymphocytic Leukemia: Narrative Review

Chronic lymphocytic leukemia (CLL), which is the most common type of leukemia in western countries in adults, is characterized by heterogeneity in clinical course, prognosis and response to the treatment. Although, in recent years a number of factors with probable prognostic value in CLL have been identified (eg NOTCH1, SF3B1 and BIRC-3 mutations, or evaluation of microRNA expression), TP53 aberrations are still the most important single factors of poor prognosis. It was found that approximately 30% of all TP53 defects are mutations lacking 17p13 deletion, whereas sole 17p13 deletion with the absence of TP53 mutation consists of 10% of all TP53 defects. The detection of del(17)(p13) and/or TP53 mutation is not a criterion itself for starting antileukemic therapy, but it is associated with an aggressive course of the disease and poor response to the standard chemoimmunotherapy. Treatment of patients with CLL harbouring TP53-deficiency requires drugs that promote cell death independently of TP53. Novel and smarter therapies revolutionize the treatment of del(17p) and/or aberrant TP53 CLL, but development of alternative therapeutic approaches still remains an issue of critical importance.

Phosphoinositide 3-Kinase Signaling in the Tumor Microenvironment: What Do We Need to Consider When Treating Chronic Lymphocytic Leukemia With PI3K Inhibitors?

Phosphoinositide 3-kinases (PI3Ks) and their downstream proteins constitute a signaling pathway that is involved in both normal cell growth and malignant transformation of cells. Under physiological conditions, PI3K signaling regulates various cellular functions such as apoptosis, survival, proliferation, and growth, depending on the extracellular signals. A deterioration of these extracellular signals caused by mutational damage in oncogenes or growth factor receptors may result in hyperactivation of this signaling cascade, which is recognized as a hallmark of cancer. Although higher activation of PI3K pathway is common in many types of cancer, it has been therapeutically targeted for the first time in chronic lymphocytic leukemia (CLL), demonstrating its significance in B-cell receptor (BCR) signaling and malignant B-cell expansion. The biological activity of the PI3K pathway is not only limited to cancer cells but is also crucial for many components of the tumor microenvironment, as PI3K signaling regulates cytokine responses, and ensures the development and function of immune cells. Therefore, the success or failure of the PI3K inhibition is strongly related to microenvironmental stimuli. In this review, we outline the impacts of PI3K inhibition on the tumor microenvironment with a specific focus on CLL. Acknowledging the effects of PI3K inhibitor-based therapies on the tumor microenvironment in CLL can serve as a rationale for improved drug development, explain treatment-associated adverse events, and suggest novel combinatory treatment strategies in CLL.

Prognostic Role of Lymphocyte/Monocyte Ratio in Chronic Lymphocytic Leukemia

Background

Chronic lymphocytic leukemia (CLL) is a B-lymphoproliferative disease with varying clinical characteristics, which occurs mostly in older ages. In studies from literature, we see that different parameters are examined to determine the prognosis of CLL. The main purpose of our study is to determine the relationship of lymphocyte/monocyte ratio (LMR) value in CLL, which has been previously shown to be a prognostic factor in various solid organ tumors and some hematological malignancies.

Methods

A total of 173 patients who were followed up between 2005 and 2019 were retrospectively analyzed. The diagnostic age, gender, laboratory, absolute lymphocyte and monocyte count, LMR and overall survival (OS), treatment and responses, recurrence, cytogenetic subtype and mortality rates were examined.

Results

The median LMR was 26.7 and it was considered as cut-off value of 26. A positive correlation was found between LMR and Rai Stage. LMR was significantly higher in patients who have an indication for treatment or who died.

Conclusions

In our study, in CLL, LMR has been shown to be over 26 in advanced stages, in relapse or with indication of a treatment. With the increase of LMR, it was found that survival and disease-free gap decreased.

Chronic lymphocytic leukemia: 2020 update on diagnosis, risk stratification and treatment

DISEASE OVERVIEW

Chronic lymphocytic leukemia (CLL) is the commonest leukemia in western countries. The disease typically occurs in elderly patients and has a highly variable clinical course. Leukemic transformation is initiated by specific genomic alterations that impair apoptosis of clonal B-cells.

DIAGNOSIS

The diagnosis is established by blood counts, blood smears, and immunophenotyping of circulating B-lymphocytes, which identify a clonal B-cell population carrying the CD5 antigen, as well as typical B-cell markers.

PROGNOSIS

The two similar clinical staging systems, Rai and Binet, create prognostic information by using results of physical examination and blood counts. Various biological and genetic markers also have prognostic value. Deletions of the short arm of chromosome 17 (del [17p]) and/or mutations of the TP53 gene, predict resistance to chemoimmunotherapy and a shorter time to progression, with most targeted therapies. A comprehensive, international prognostic score (CLL-IPI) integrates genetic, biological and clinical variables to identify distinct risk groups of CLL patients.

THERAPY

Only patients with active or symptomatic disease, or with advanced Binet or Rai stages require therapy. When treatment is indicated, several options exist for most CLL patients: a combination of venetoclax with obinutuzumab, ibrutinib monotherapy, or chemoimmunotherapy. For physically fit patients younger than 65 (in particular when presenting with a mutated IGVH gene), chemoimmunotherapy with fludarabine, cyclophosphamide and rituximab remains a standard therapy, since it may have curative potential. At relapse, the initial treatment may be repeated, if the treatment-free interval exceeds 3 years. If the disease relapses earlier, therapy should be changed using an alternative regimen. Patients with a del (17p) or TP53 mutation are a different, high-risk category and should be treated with targeted agents. An allogeneic SCT may be considered in relapsing patients with TP53 mutations or del (17p), or patients that are refractory to inhibitor therapy.

FUTURE CHALLENGES

Targeted agents (ibrutinib, idelalisib, venetoclax, obinutuzumab) will be increasingly used in combination to allow for short, but potentially definitive therapies of CLL. It remains to be proven that they generate a superior outcome when compared to monotherapies with inhibitors of Bruton tyrosine kinase, which can also yield long-lasting remissions. Moreover, the optimal sequencing of drug combinations is unknown. Therefore, CLL patients should be treated in clinical trials whenever possible.

HIF-1α is over-expressed in leukemic cells from TP53-disrupted patients and is a promising therapeutic target in chronic lymphocytic leukemia

In chronic lymphocytic leukemia (CLL), the hypoxia-inducible factor 1 (HIF-1) regulates the response of tumor cells to hypoxia and their protective interactions with the leukemic microenvironment. In this study, we demonstrate that CLL cells from TP53-disrupted (TP53^dis) patients have constitutively higher expression levels of the α-subunit of HIF-1 (HIF-1α) and increased HIF-1 transcriptional activity compared to the wild-type counterpart. In the TP53^dis subset, HIF-1α upregulation is due to reduced expression of the HIF-1α ubiquitin ligase von Hippel-Lindau protein (pVHL). Hypoxia and stromal cells further enhance HIF-1α accumulation, independently of TP53 status. Hypoxia acts through the downmodulation of pVHL and the activation of the PI3K/AKT and RAS/ERK1-2 pathways, whereas stromal cells induce an increased activity of the RAS/ERK1-2, RHOA/RHOA kinase and PI3K/AKT pathways, without affecting pVHL expression. Interestingly, we observed that higher levels of HIF-1A mRNA correlate with a lower susceptibility of leukemic cells to spontaneous apoptosis, and associate with the fludarabine resistance that mainly characterizes TP53^dis tumor cells. The HIF-1α inhibitor BAY87-2243 exerts cytotoxic effects toward leukemic cells, regardless of the TP53 status, and has anti-tumor activity in Em-TCL1 mice. BAY87-2243 also overcomes the constitutive fludarabine resistance of TP53^dis leukemic cells and elicits a strongly synergistic cytotoxic effect in combination with ibrutinib, thus providing preclinical evidence to stimulate further investigation into use as a potential new drug in CLL.

Assessment of microRNA expression in leukemic cells as predictors of sensitivity to purine nucleoside analogs, fludarabine and cladribine, in chronic lymphocytic leukemia patients

Background: Great progress has been achieved lately in the therapy for chronic lymphocytic leukemia (CLL), one of the most frequently diagnosed adult leukemias. New classes of drugs, such as kinase inhibitors and BCL-2 protein antagonists, have been approved for treatment of CLL patients. Despite the abovementioned therapies the disease can still be effectively treated with purine nucleoside analogs (PNA). However, some patients, for example, those with TP53 gene abnormalities, become resistant, and the other factors involved in the therapy resistance are still being investigated. This study was aimed at analyzing the possible role of microRNAs as markers predicting the outcome of chemotherapy based on PNA – fludarabine and cladribine in CLL patients.

Methods: The expression of miR-21, miR-34a, miR-181a and miR-221 in previously separated leukemic cells was assessed with the use of qRQ-PCR technique at the moment of diagnosis in 40 CLL patients. In turn, apoptosis induced by fludarabine and cladribine in 24-hour cell culture was evaluated by determining the increase in the percentage of apoptotic cells of CD5+/CD19+/Cas3+ phenotype, using a flow cytometry method. Nine of the 40 studied subjects were treated with fludarabine-based regimens and were analyzed with regards to in vivo response to PNA.

Results: We detected a significantly higher PNA-induced apoptosis rate in patients with high miR-34a expression in comparison to low expression ones. Interestingly, such differences were detected particularly in standard cytogenetic patients.

Conclusions: These results may prove an important role of miR-34a expression as a predictor of apoptosis, even in cases when other risk factors like cytogenetic abnormalities are absent. An assessment of microRNAs expression seems to be useful as an indicator of sensitivity to PNA and may help to predict PNA-based therapy outcome.

Overview of non-coding mutations in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is the most frequent leukemia type in which the genetic alterations influencing the clinico‐biological course are not entirely understood. CLL has a heterogeneous course, with some patients showing an indolent course and others experiencing an aggressive course. Whole‐genome sequencing and whole‐exome sequencing studies identified recurrently mutated genes in CLL and profiled its clonal evolution patterns. However, more recent whole‐genome sequencing studies also identified variants in non‐coding sequences of the CLL genome, revealing important lesions outside the protein‐coding regions. Here we describe the most representative non‐coding lesion of the CLL genome, including lesions in the 3′‐UTR region of NOTCH1 which result in the truncation of the NOTCH1 protein PEST domain, and non‐coding mutations in an enhancer region on chromosome 9p13 which result in reduced expression of the PAX5 transcription factor. In addition, we describe the role of microRNA in CLL, in particular the miR15a/miR16‐1 microRNA recurrently affected by deletions of chromosome 13q14. Together, new findings in non‐coding genome genetic lesions provide a more complete portrait of the genomic landscape of CLL with clinical implications.

SENP2 exerts an anti‑tumor effect on chronic lymphocytic leukemia cells through the inhibition of the Notch and NF‑κB signaling pathways

Chronic lymphocytic leukemia (CLL) is one of the most often diagnosed hematological malignant tumors in the Western world and a type of inert B-cell lymphoma that commonly attacks the elderly. Small ubiquitin related modifier (SUMO)-specific protease 2 (SENP2) can act as a suppressor in various types of cancer by regulating the stability of β-catenin to affect the Notch signaling pathway; however, it has a low expression level in CLL cells. In this study, we firstly used western blot analysis and RT-qPCR to detect the protein and mRNA expression levels of SENP2 in the peripheral blood of patients with CLL and healthy volunteers. Secondly, we overexpressed or knocked down the expression of SENP2 in CLL cells and then determined the cell invasive and chemotactic ability in a Transwell assay and chemotaxis assay. We examined the sensitivity of the cells to cytarabine and dexamethasone via a CCK-8 assay and determined the cell apoptotic condition and the expression of the Notch signaling pathway using flow cytometry and western blot analysis. The results demonstrated that the patients with CLL had relatively low expression levels of SENP2. The overexpression of SENP2 in the CLL cells decreased their invasive and proliferative ability, as well as their chemotactic response and enhanced their sensitivity to cytarabine and dexamethasone, while it promoted cell apoptosis. The silencing of SENP2 in the CLL cells generally produced the opposite results. We thus hypothesized that the overexpression of SENP2 downregulated β-catenin expression, thus inhibiting the Notch signaling pathway in CLL cells. Moreover, the nuclear factor (NF)-κB signaling pathway was also regulated by the overexpression of SENP2. On the whole, the findings of this study indicate tha SENP2 can act as a tumor suppressor in CLL cells, and may thus prove to be a novel target for CLL treatment in clinical practice.

MicroRNA-92a-3p overexpression in peripheral blood mononuclear cells is an independent predictor of prolonged overall survival of patients with chronic lymphocytic leukemia

MicroRNA-92a-3p (miR-92a-3p) derives from the oncogenic miR-17/92 cluster and its highly homologous miR-106a/363 cluster. miR-92a-3p regulates the expression of key transcription factors such as HIF1 and inhibits SOCS1 to enhance the anti-apoptotic STAT3/IL6 signaling pathway. In this study, we assessed the putative usefulness of miR-92a-3p as a prognostic and/or diagnostic biomarker in chronic lymphocytic leukemia (CLL). For this purpose, total RNA was extracted from mononuclear cells isolated from the peripheral blood of 88 CLL patients and 36 non-leukemic blood donors, was polyadenylated and reversely transcribed. miR-92a-3p expression was quantified using an accurate qPCR method. miR-92a-3p levels were significantly lower in peripheral blood mononuclear cells of CLL patients. Overall survival (OS) analysis revealed that high miR-92a-3p expression predicts significantly prolonged OS of CLL patients. Interestingly, miR-92a-3p overexpression remains a significant prognosticator in subgroups of CLL patients with distinct prognosis. In conclusion, miR-92a-3p overexpression is a potential surrogate biomarker of favorable outcome of CLL patients.

Circular RNA circ-CBFB promotes proliferation and inhibits apoptosis in chronic lymphocytic leukemia through regulating miR-607/FZD3/Wnt/β-catenin pathway

Circular RNA (circRNA) belongs to the non-coding RNA family and is involved in various human cancers, such as lung cancer and colorectal cancer. Nevertheless, whether circRNA expression is related to chronic lymphocytic leukemia (CLL) progression remains largely unclear. In our study, we investigated the role of circ-CBFB in CLL. We found that circ-CBFB was markedly overexpressed in CLL cells compared to normal controls. Furthermore, we found that circ-CBFB could serve as a diagnostic and prognostic biomarker for CLL patients. We also explored the physiological function of circ-CBFB. We found that circ-CBFB knockdown significantly suppressed CLL cell proliferation, arrested cell cycle progression, and induced cellular apoptosis. In terms of its mechanism, we identified circ-CBFB as a sponge of miR-607, which targeted FZD3. By inhibiting miR-607 availability, circ-CBFB promoted FZD3 expression, leading to the activation of the Wnt/β-catenin pathway and consequent CLL progression. Taken together, our findings revealed that the circ-CBFB/miR-607/FZD3/Wnt/β-catenin regulatory signaling cascade contributes to CLL progression.

Chronic lymphocytic leukemia: 2017 update on diagnosis, risk stratification, and treatment

DISEASE OVERVIEW

Chronic lymphocytic leukemia (CLL) is the commonest leukemia in western countries. The disease typically occurs in elderly patients and has a highly variable clinical course. Leukemic transformation is initiated by specific genomic alterations that impair apoptosis of clonal B cells.

DIAGNOSIS

The diagnosis is established by blood counts, blood smears, and immunophenotyping of circulating B lymphocytes, which identify a clonal B-cell population carrying the CD5 antigen and B-cell markers.

PROGNOSIS

Two prognostic staging systems exist, the Rai and Binet staging systems, which are established by physical examination and blood counts. Various biological and genetic markers also have prognostic value. Deletions of the short arm of chromosome 17 (del(17p)) and/or mutations of the TP53 gene predict resistance to available chemotherapies. A comprehensive prognostic score (CLL-IPI) using genetic, biological, and clinical variables has recently been developed allowing to classify CLL into very distinct risk groups.

THERAPY

Patients with active or symptomatic disease or with advanced Binet or Rai stages require therapy. For physically fit patients, chemoimmunotherapy with fludarabine, cyclophosphamide, and rituximab remains the current standard therapy. For unfit patients, currently available evidence supports two options for a first-line therapy: chlorambucil combined with an anti-CD20 antibody (obinutuzumab or rituximab or ofatumumab) or a continuous therapy with ibrutinib. At relapse, the initial treatment may be repeated, if the treatment-free interval exceeds 3 years. If the disease relapses earlier, therapy should be changed using alternative agents such as bendamustine (plus rituximab), alemtuzumab, lenalidomide, ofatumumab, ibrutinib, idelalisib, or venetoclax. Patients with a del(17p) or TP53 mutation can be treated with ibrutinib, venetoclax, or a combination of idelalisib and rituximab. An allogeneic SCT may be considered in relapsing patients with TP53 mutations or del(17p) or patients that are refractory to chemoimmunotherapy and the novel inhibitors.

FUTURE CHALLENGES

The new agents (ibrutinib, idelalisib, venetoclax, and obinutuzumab) hold the potential to significantly improve the outcome of CLL patients. However, their optimal use (in terms of combination, sequence, and duration) remains unknown. Therefore, CLL patients should be treated in clinical trials whenever possible.

Concepts of Chronic Lymphocytic Leukemia Pathogenesis: DNA Damage Response and Tumor Microenvironment

Pathogenesis of chronic lymphocytic leukemia (CLL) is characterized by specific genetic aberrations and alterations of cellular signaling pathways. In particular, a disturbed DNA damage response (DDR) and an activated B-cell receptor signaling pathway play a major role in promoting CLL cell survival. External stimuli are similarly essential for CLL cell survival and lead to activation of the PI3K/AKT and MAPK pathways. Activation of nuclear factor-kappa B (NFkB) influences the disturbed anti-apoptotic balance of CLL cells. Losses or disabling mutations in TP53 and ATM are frequent events in chemotherapy-naïve patients and are further enriched in chemotherapy-resistant patients. As these lesions define key regulatory elements of the DDR pathway, they also determine treatment response to genotoxic therapy. Novel therapeutic strategies therefore try to circumvent defective DDR signaling and to suppress the pro-survival stimuli received from the tumor microenvironment. With increasing knowledge on specific genetic alterations of CLL, we may be able to target CLL cells more efficiently even in the situation of mutated DDR pathways or protection by microenvironmental stimuli.

The rate of in vitro fludarabine-induced peripheral blood and bone marrow cell apoptosis may predict the chemotherapy outcome in patients with chronic lymphocytic leukemia

Purpose

The problem of drug sensitivity and predicting the outcome of chemotherapy seems to be of great importance in hemato-oncological disorders. There are some factors that can help to predict effects of chemotherapy in chronic lymphocytic leukemia (CLL), such as presence of del17p, del11q, or TP53 gene mutations, which result in resistance to purine analogues and alkylating drugs. Despite the new therapeutic options introduced recently, purine analogues in combination with cyclophosphamide and the monoclonal antibody rituximab is still the gold standard for the first-line treatment of fit patients with CLL. The aim of this study was to assess whether the rate of apoptosis caused by one of purine analogues—fludarabine in cell cultures differs between patients who clinically respond to fludarabine-based chemotherapy and those who do not respond.

Methods

CLL leukemic cells, obtained from peripheral blood and bone marrow of 23 patients, were cultured in the presence of fludarabine. After 24 h of incubation, the rate of apoptosis, indicated by the expression of active caspase-3, was assessed with flow cytometry and then analyzed regarding clinical response to fludarabine-based regimens.

Results

The percentage of apoptotic cells induced by fludarabine was significantly higher in the group of patients who achieved remission in comparison to the group with no response to purine analogues therapy. Interestingly, we observed that among the patients who did not respond to chemotherapy, the presence of del17p and del11q was detected only once. Other non-responders had no detectable genetic abnormalities.

Conclusions

Based on these results, it can be presumed that in vitro drug sensitivity test, which is easy to perform, may predict the outcome of fludarabine-based chemotherapy in CLL patients.

Electronic supplementary material

The online version of this article (doi:10.1007/s00228-015-1893-0) contains supplementary material, which is available to authorized users.

Targeting ATM-deficient CLL through interference with DNA repair pathways

Chronic lymphocytic leukemia (CLL) is the most common form of leukemia in the Western world and accounts for approximately 30% of adult leukemias and 25% of non-Hodgkin lymphomas. The median age at diagnosis is 72 years. During recent years numerous genetic aberrations have been identified that are associated with an aggressive course of the disease and resistance against genotoxic chemotherapies. The DNA damage-responsive proapoptotic ATM-CHK2-p53 signaling pathway is frequently mutationally inactivated in CLL either through large deletions on chromosome 11q (ATM) or 17p (TP53), or through protein-damaging mutations. Here, we focus on the role of ATM signaling for the immediate DNA damage response, DNA repair and leukemogenesis. We further discuss novel therapeutic concepts for the targeted treatment of ATM-defective CLLs. We specifically highlight the potential use of PARP1 and DNA-PKcs inhibitors for the treatment of ATM-mutant CLL clones. Lastly, we briefly discuss the current state of genetically engineered mouse models of the disease and emphasize the use of these preclinical tools as a common platform for the development and validation of novel therapeutic agents.

Chronic lymphocytic leukemia: 2015 Update on diagnosis, risk stratification, and treatment

DISEASE OVERVIEW

Chronic lymphocytic leukemia (CLL) is the commonest leukemia in western countries. The disease typically occurs in elderly patients and has a highly variable clinical course. Leukemic transformation is initiated by specific genomic alterations that impair apoptosis of clonal B-cells.

DIAGNOSIS

The diagnosis is established by blood counts, blood smears, and immunophenotyping of circulating B-lymphocytes, which identify a clonal B-cell population carrying the CD5 antigen as well as B-cell markers.

PROGNOSIS

Two prognostic staging systems exist, the Rai and Binet staging systems, which are established by physical examination and blood counts. Various biological and genetic markers also have prognostic value. Deletions of the short arm of chromosome 17 (del(17p)) predict resistance to available chemotherapies. Comprehensive prognostic scores are currently being developed.

THERAPY

Patients with active or symptomatic disease or with advanced Binet or Rai stages require therapy. For physical fit patients, chemoimmunotherapy with fludarabine, cyclophosphamide, and rituximab remains the current standard therapy. For unfit patients, treatment with an anti-CD20 antibody (obinutuzumab or rituximab or ofatumumab) plus a milder chemotherapy (Chlorambucil) may be applied. At relapse, the initial treatment may be repeated, if the treatment-free interval exceeds two to three years. If the disease relapses earlier, therapy should be changed using alternative agents such as bendamustine (plus rituximab), alemtuzumab, lenalidomide, ofatumumab, ibrutinib, or idelalisib. Patients with a del(17p) or TP53 mutation can be treated with ibrutinib or a combination of idelalisib and rituximab. An allogeneic SCT may be considered in relapsing patients with TP53 mutations or del(17p) or patients that are refractory to repeated chemoimmunotherapies. Future challenges: Several new agents (e.g., ibrutinib, idelalisib, obinutuzumab) hold the potential to improve the outcome of patients with CLL. However, their optimal use (in terms of combination, sequence, and duration) is unknown. Therefore, CLL patients should be treated in clinical trials whenever possible.

DNA damage response and evasion from immunosurveillance in CLL: new options for NK cell-based immunotherapies

Chronic lymphocytic leukemia (CLL) is the most prominent B cell malignancy among adults in the Western world and characterized by a clonal expansion of B cells. The patients suffer from severe immune defects resulting in increased susceptibility to infections and failure to generate an antitumor immune response. Defects in both, DNA damage response (DDR) pathway and crosstalk with the tissue microenvironment have been reported to play a crucial role for the survival of CLL cells, therapy resistance and impaired immune response. To this end, major advances over the past years have highlighted several T cell immune evasion mechanisms in CLL. Here, we discuss the consequences of an impaired DDR pathway for detection and elimination of CLL cells by natural killer (NK) cells. NK cells are considered to be a major component of the immunosurveillance in leukemia but NK cell activity is impaired in CLL. Restoration of NK cell activity using immunoligands and immunoconstructs in combination with the conventional chemotherapy may provide a future perspective for CLL treatment.

Variable induction of PRDM1 and differentiation in chronic lymphocytic leukemia is associated with anergy

Despite antigen engagement and intact B-cell-receptor (BCR) signaling, chronic lymphocytic leukemia (CLL) cells fail to undergo terminal differentiation. We hypothesized that such failure may be due to anergy, as CLL cells exhibit variable levels of nonresponsiveness to surface IgM stimulation that is reversible in vitro. Moreover, anergy is associated with reduced differentiation capacity in normal B cells. We investigated responses of CLL cells to two potent differentiation-promoting agents, IL-21 and cytosine guanine dinucleotide-enriched oligo-deoxynucleotides. The induction of PR domain-containing protein 1 (PRDM1; also known as Blimp-1), a critical regulator of plasmacytic differentiation, by these agents was closely correlated but varied between individual cases, despite functionally intact IL-21 receptor- and Toll-like receptor 9-mediated signal transducer and activator of transcription 3, and nuclear factor-κB pathways. PRDM1 induction was inversely correlated with the extent of anergy as measured by the ability to mobilize intracellular Ca(2+) following BCR crosslinking. PRDM1 responsiveness was associated with other markers of differentiation and proliferation but not with differences in apoptosis. The ability to induce PRDM1 did correlate with differential transcriptional and epigenetic regulation of the PRDM1 gene. These studies extend our understanding of CLL pathobiology, demonstrating that reduced differentiation capacity may be a consequence of anergy. Epigenetic drugs may offer possibilities to reactivate PRDM1 expression as part of novel differentiation therapy approaches.

Chronic lymphocytic leukemia: 2013 update on diagnosis, risk stratification and treatment

DISEASE OVERVIEW

Chronic lymphocytic leukemia (CLL) is the commonest leukemia in western countries. The disease typically occurs in elderly patients and has a highly variable clinical course. Leukemic transformation is initiated by specific genomic alterations that impair apoptosis of clonal B-cells.

DIAGNOSIS

The diagnosis is established by blood counts, blood smears, and immunophenotyping of circulating B-lymphocytes, which identify a clonal B-cell population carrying the CD5 antigen as well as B-cell markers.

PROGNOSIS

Two prognostic staging systems exist, the Rai and Binet staging systems, which are established by physical examination and blood counts. Various biological and genetic markers also have prognostic value. Deletions of the short arm of chromosome 17 (del(17p)) predict resistance to most available therapies.

THERAPY

Patients with active or symptomatic disease or with advanced Binet or Rai stages require therapy. For physical fit patients, chemoimmunotherapy with fludarabine, cyclophosphamide and rituximab represents the current standard therapy. For unfit patients, treatment with an anti-CD20 antibody plus a milder chemotherapy (chlorambucil) is currently established as standard treatment. At relapse, the initial treatment may be repeated, if the treatment-free interval exceeds two years. If the disease relapses earlier, alternative therapies such as bendamustine alone or with rituximab, alemtuzumab, lenalidomide, or ofatumumab should be used. Patients with a del(17p) or TP53 should be considered for an allogeneic SCT.

FUTURE CHALLENGES

Several new agents (e.g., ibrutinib, obinutuzumab) hold the potential to change standard of CLL treatment in the next 6-12 months. Therefore, CLL patients should be included into current clinical trials whenever possible.

High CD74 expression correlates with ZAP70 expression in B cell chronic lymphocytic leukemia patients

Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults in Western countries. It is characterized by heterogeneous clinical course of the disease and new prognostic factors are still needed. CD74 plays an important role in signal transduction in B cell proliferation and survival pathway. CD74 expression has been shown in solid tumors and has been connected with poor prognosis and tumor progression. The aim of the study was to evaluate the expression of CD74 in chronic lymphocytic leukemia patients with combination with other known prognostic factors. Expression of CD74 was determined in 90 patients and 28 healthy controls. CD74 expression was significantly higher in CLL group than in controls. There was positive correlation between CD74 and ZAP70 expression (p = 0.008). High expression of CD74 was positively correlated with more advanced stage of the disease (p = 0.02). No correlation was shown between CD74 and sex, mutational status IgVH and time to first treatment.

Aggressive disease defined by cytogenetics is associated with cytokine dysregulation in CLL/SLL patients

Early treatment of CLL/SLL does not impact survival-reflecting limitations in detecting progression early and identifying asymptomatic patients likely to benefit from early treatment. Improved understanding of CLL/SLL biology would identify better prognostic/predictive markers. This study attempts to address these issues by determining the relationship between cytokine aberrations and poor clinical outcomes in CLL/SLL in the context of a genetic-based prognostic model. Fifty-nine serum cytokines/chemokines were measured in 28 untreated CLL/SLL patients. Patients were stratified as GR or int/PR using cytogenetics. Comparison of CLL/SLL with 28 HCs revealed increased expression of Th2 cytokines (IL-10, IL-5, sIL-2Rα; P≤0.01) and decreased levels of Th1 cytokines (IL-17, IL-23, IFN-γ; P≤0.003). In a multivariate analysis of GR versus int/PR groups, differential expression of sIL-2Rα maintained significance with increased expression in int/PR CLL/SLL. With median follow-up of 54.3 months after diagnosis, four patients incurred disease progression, with an IL-17/sIL-2Rα model predicting need for treatment in all cases. In summary, specific cytokine signatures are associated with genetically defined aggressive disease and predict need for therapy. This suggests utility in detecting disease progression early, identifying those likely to incur a survival advantage with early treatment, and directing future therapy.