Chronic lymphocytic leukaemia

"Role of the B-cell receptor and the microenvironment in chronic lymphocytic leukemia''

Despite significant progress in treatment, chronic lymphocytic leukemia (CLL) remains an incurable disease. Advances have been made to understand the molecular pathogenesis underlying CLL progression and treatment resistance. We here review the available evidences concerning the role of the B-cell receptor (BCR) and the tumor microenvironment interactions in CLL pathogenesis. Antigen likely has a key role in the selection of the tumoral clone, the mutational status of immunoglobulin genes is a strong prognostic predictor and BCR signaling has been postulated to have a role for CLL trafficking and interaction with the stromal microenvironment. There is also important evidence, favoring a role for the microenvironment in CLL pathogenesis. Most, if not all, proliferative events occur in the lymph nodes and bone marrow, where leukemic cells receive through microenvironment interactions survival signals aiming to avoid apoptosis and acquire favorable tumoral growing conditions. In addition, the tumoral microenvironment appears to be the site where the acquisition of additional genetic lesions in the clone occur, which should greatly influence clinical outcome. The advent of new tyrosine kinase inhibitors which seem to be able to modulate microenvironment interactions and circumvent the p53 deletion have generated significant promise by raising the possibility that they could provide significant progress in disease treatment.

Opticin, a small leucine-rich proteoglycan, is uniquely expressed and translocated to the nucleus of chronic lymphocytic leukemia cells

Background

Opticin (OPTC) is a member of the small leucine-rich proteoglycan (SLRP) family and is localized particularly in certain extracellular matrices. We have previously reported the unique expression of another SLRP, fibromodulin (FMOD) in the leukemic cells of patients with chronic lymphocytic leukemia (CLL). OPTC is located in the same region as FMOD on chromosome 1 (1q32.1). Cluster up-regulation of genes may be observed in malignancies and the aim of the present study was to analyze the expression of OPTC in CLL cells.

Methods

The expression of OPTC was tested by RT-PCR and realtime qPCR in PBMC from CLL patients, other hematological malignancies and healthy controls. The presence of OPTC protein, and its subcellular localization, was investigated using fractionation methods where the obtained lysate fractions were analyzed by Western blotting. Deglycosylation experiments were performed to investigate the glycosylation status of the CLL OPTC.

Results

OPTC was expressed at the gene level in all patients with CLL (n = 90) and in 2/8 patients with mantle cell lymphoma (MCL) but not in blood mononuclear cells of healthy control donors (n = 20) or in tumor samples from nine other types of hematological malignancies. OPTC was detected by Western blot in all CLL samples analyzed (n = 30) but not in normal leukocytes (n = 10). Further analysis revealed a CLL-unique unglycosylated 37 kDa core protein that was found to be located preferentially in the cell nucleus and endoplasmic reticulum (ER) of the CLL cells.

Conclusions

A 37 kDa unglycosylated OPTC protein was detected in ER and in the nucleus of CLL cells and not in healthy control donors. The function of this OPTC core protein remains unclear but its CLL-specific expression and subcellular localization warrants further investigations in the pathobiology of CLL.

Role of CTLA4 in the proliferation and survival of chronic lymphocytic leukemia

Earlier, we reported that CTLA4 expression is inversely correlated with CD38 expression in chronic lymphocytic leukemia (CLL) cells. However, the specific role of CTLA4 in CLL pathogenesis remains unknown. Therefore, to elucidate the possible role of CTLA4 in CLL pathogenesis, CTLA4 was down-regulated in primary CLL cells. We then evaluated proliferation/survival in these cells using MTT, (3)H-thymidine uptake and Annexin-V apoptosis assays. We also measured expression levels of downstream molecules involved in B-cell proliferation/survival signaling including STAT1, NFATC2, c-Fos, c-Myc, and Bcl-2 using microarray, PCR, western blotting analyses, and a stromal cell culture system. CLL cells with CTLA4 down-regulation demonstrated a significant increase in proliferation and survival along with an increased expression of STAT1, STAT1 phosphorylation, NFATC2, c-Fos phosphorylation, c-Myc, Ki-67 and Bcl-2 molecules. In addition, compared to controls, the CTLA4-downregulated CLL cells showed a decreased frequency of apoptosis, which also correlated with increased expression of Bcl-2. Interestingly, CLL cells from lymph node and CLL cells co-cultured on stroma expressed lower levels of CTLA4 and higher levels of c-Fos, c-Myc, and Bcl-2 compared to CLL control cells. These results indicate that microenvironment-controlled-CTLA4 expression mediates proliferation/survival of CLL cells by regulating the expression/activation of STAT1, NFATC2, c-Fos, c-Myc, and/or Bcl-2.

Accelerated development of chronic lymphocytic leukemia in New Zealand Black mice expressing a low level of interferon regulatory factor 4

A recent genome-wide SNP association study identified IRF4 as a major susceptibility gene for chronic lymphocytic leukemia (CLL). Moreover, the SNPs located in the 3' UTR of the IRF4 gene have been linked to a down-regulation of IRF4. However, whether a low level of IRF4 is critical for CLL development remains unclear. New Zealand Black (NZB) mice are a naturally occurring, late-onset mouse model of CLL. To examine the role of a reduced level of IRF4 in CLL development, we generated, through breeding, IRF4 heterozygous mutant mice in the NZB background (NZB IRF4(+/-)). Our results show that CLL development is accelerated dramatically in the NZB IRF4(+/-) mice. The average onset of CLL in NZB mice is 12 months, but CLL cells can be detected in NZB IRF4(+/-) mice at 3 months of age. By 5 months of age, 80% of NZB IRF4(+/-) mice developed CLL. CLL cells are derived from B1 cells in mice. Interestingly, NZB IRF4(+/-) B1 cells exhibit prolonged survival, accelerated self-renewal, and defects in differentiation. Although NZB IRF4(+/-) CLL cells are resistant to apoptosis, high levels of IRF4 inhibit their survival. High levels of IRF4 also reduce the survival of MEC-1 human CLL cells. Our analysis further reveals that high levels of IRF4 suppress Akt activity and can do so without the IRF4 DNA binding domain. Thus, our findings reveal a causal relationship between a low level of IRF4 and the development of CLL and establish IRF4 as a novel regulator in the pathogenesis of CLL.

Analysis of activation-induced cytidine deaminase mRNA levels in patients with chronic lymphocytic leukemia with different cytogenetic status

Activation induced cytidine deaminase (AID) enzyme, which converts cytosine into uracil and is expressed only by activated B lymphocytes, plays a role in B cells in both the mechanisms of somatic hypermutation (SHM) and class switch recombination (CSR). There are studies showing that AID can cause numerous translocations in different lymphoproliferative diseases. Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of monoclonal B cells in bone marrow and peripheral blood. The predictability and clinical status of B-CLL are difficult to determine. About 30-50% of patients have chromosomal abnormalities. AID, which is thought to create fraction segments for translocations, might also cause deletions in DNA regions of 17p13, 11q22.3, 13q14 and 13q34 that are associated with prognostic implications in patients with CLL. In this study, the AID gene expression in patients with CLL with and without deletions was investigated. When compared to healthy subjects and patients without deletions, increased levels of AID expression in patients with deletions of 17p13, 11q22.3 or 13q14 were found, but not for the 13q34 region. Our results show that AID expression may be associated with deletions in patients with CLL.

Attenuating homologous recombination stimulates an AID-induced antileukemic effect

Inhibition of the RAD51 homologous recombination factor prevents the repair of AID-initiated DNA breaks and induces apoptosis preferentially in AID-expressing human CLL.

Activation-induced cytidine deaminase (AID) is critical in normal B cells to initiate somatic hypermutation and immunoglobulin class switch recombination. Accumulating evidence suggests that AID is also prooncogenic, inducing cancer-promoting mutations or chromosome rearrangements. In this context, we find that AID is expressed in >40% of primary human chronic lymphocytic leukemia (CLL) cases, consistent with other reports. Using a combination of human B lymphoid leukemia cells and mouse models, we now show that AID expression can be harnessed for antileukemic effect, after inhibition of the RAD51 homologous recombination (HR) factor with 4,4′-diisothiocyanatostilbene-2-2′-disulfonic acid (DIDS). As a proof of principle, we show that DIDS treatment inhibits repair of AID-initiated DNA breaks, induces apoptosis, and promotes cytotoxicity preferentially in AID-expressing human CLL. This reveals a novel antineoplastic role of AID that can be triggered by inhibition of HR, suggesting a potential new paradigm to treat AID-expressing tumors. Given the growing list of tumor types with aberrant AID expression, this novel therapeutic approach has potential to impact a significant patient population.

The changing paradigm of chronic lymphocytic leukemia management

B cell-chronic lymphocytic leukemia (CLL), the commonest adult leukemia in western world, is today most often diagnosed at early-stage, following the accidental detection of lymphocytosis during a routine blood analysis. Moreover, the expectations of CLL patients have dramatically changed in the past decade and for the first time a significant overall survival improvement has been demonstrated in the disease--at least in the younger and fit patients--with the use of the FCR regimen, which combines rituximab fludarabine and cyclophosphamide. New drugs and new regimens are currently being developed for the relapsed patients and for those too old or too frail to receive aggressive treatments. Some of these promising compounds will likely be part of the future front-line treatments. Additionally, the increasing knowledge on the molecular features that predict the clinical outcome may soon result in a molecular classification of the disease. These acquisitions are producing a migration from palliative care to a curative and individually-tailored approach. In this review we tried to summarize the advances achieved in the past decade and help the specialists in internal medicine and the general practitioners to understand the completely changed scenario in which the disease should nowadays be managed.

Immunoglobulin gene rearrangements and mutational status in argentinian patients with chronic lymphocytic leukemia

BACKGROUND

Chronic lymphocytic leukemia (CLL) is a clinically heterogeneous disease. The mutational status of the immunoglobulin heavy chain variable (IGHV) region represents one of the best prognostic markers and defines 2 disease subgroups: mutated (M-CLL) and unmutated (UM-CLL), with different clinical course.

MATERIALS AND METHODS

IGHV-D-J gene rearrangements and mutational status were analyzed in 73 Argentinian patients with CLL, 22 previously treated, by reverse transcriptase-polymerase chain reaction and bidirectional sequencing. The results were compared with those reported in other geographic regions. Fluorescence in situ hybridization analysis was also performed.

RESULTS

A total of 43 (58.9%) cases were of patients with M-CLL, and 30 (41.1%) were patients with UM-CLL. Deletion of chromosome 13q14 as a single alteration was more frequently observed in the M-CLL group (48%) than in the UM-CLL group (24%). In the M-CLL group, the proportion of cases with deletion of chromosome 13q14 was significantly higher than those with +12 and those with deletions of chromosomes 17p and 11q (P = .003). The most frequently used IGHV families were IGHV3 > IGHV1 > IGHV4, which are different from those observed in Asian, Brazilian, and Uruguayan series. The IGHV3-23 gene (10.8%) was the most commonly used, followed by IGHV1-69 (9.5%), IGHV4-59 and IGHV2-5 (6.8% each), and IGHV3-21 and IGHV3-30 (5.4% each). IGHV4-34 showed the lowest frequency (2.7%) in our cohort compared with published data, whereas IGHV4-59, IGHV3-72, and IGHV2-5 were overexpressed in our series. Stereotyped HCDR3 (heavy chain complementary determining region 3) was found in 9.5% of patients.

CONCLUSIONS

Our results showed that Argentinian patients with CLL display an IGHV gene usage that resembles that observed in Western countries and exhibited interesting similarities and differences with respect to published series from other Latin American populations, which reflect variations in the genetic background.

Clinical implications of the molecular genetics of chronic lymphocytic leukemia

Genetics and molecular genetics have contributed to clarify the biological bases of the clinical heterogeneity of chronic lymphocytic leukemia. In recent years, our knowledge of the molecular genetics of chronic lymphocytic leukemia has significantly broadened, offering potential new clinical implications. Mutations of TP53 and ATM add prognostic information independently of fluorescence in situ hybridization cytogenetic stratification. In addition, next generation sequencing technologies have allowed previously unknown genomic alterations in chronic lymphocytic leukemia to be identified. Mutations of NOTCH1, SF3B1 and BIRC3 have been associated with short time to progression and survival. Each of these lesions recognizes a different distribution across different clinical phases and biological subgroups of the disease. The clinical implications of these molecular lesions are in some instances well established, such as in the case of patients with TP53 disruption, who should be considered for alternative therapies/allogeneic stem cell transplant upfront, or in patients with ATM disruption, who are candidates to rituximab-based immunochemotherapy. On the contrary, NOTCH1, SF3B1 and BIRC3 mutations appear to have a specific significance, the clinical value of which is currently being validated, i.e. association to Richter syndrome transformation for NOTCH1 mutations, and short progression-free survival after treatment for SF3B1 mutations. Certainly, these new lesions have helped clarify the molecular bases of chronic lymphocytic leukemia aggressiveness beside TP53 disruption. This review covers the recent advancements in our understanding of the molecular genetics of chronic lymphocytic leukemia and discusses how they are going to translate into clinical implications for patient management.

Methylation of tumor suppressor microRNAs: lessons from lymphoid malignancies

miRNAs are a group of small noncoding RNAs measuring 19-25 nucleotides. Sequence-specific binding of miRNAs to the 3´ untranslated regions of target genes leads to translational repressions. Dysregulation of miRNA expression involved in cancer can be triggered by multiple mechanisms including aberrant DNA methylation of the miRNA gene promoter. Of note, DNA methylation of tumor suppressor miRNAs has been implicated in various human cancers. Moreover, miRNA silencing mediated by aberrant promoter DNA methylation can potentially be reversed by hypomethylating agents, and hence may pose a new therapeutic target in cancer. In this review, the authors will focus on the aberrant methylation of miRNAs in the pathogenesis of lymphoid malignancies including chronic lymphocytic leukemia, multiple myeloma and acute lymphoblastic leukemia.

LCK is an important mediator of B-cell receptor signaling in chronic lymphocytic leukemia cells

B-cell receptor (BCR) signals promote survival of chronic lymphocytic leukemia (CLL) cells, and it is believed that overexpressed and constitutively active Lyn mediates this signaling. Here, we show that CLL cells express lymphocyte-specific protein tyrosine kinase (LCK) and that inhibition of this Src family tyrosine kinase with the specific inhibitor [4-amino-5-(4-phenoxyphenyl)-7H-pyrrolo[3,2-d]pyrimidin-7-yl-cyclopentane (Lck-i)], or reduction of its expression with siRNA, blocks the induction of CD79a, Syk, inhibitor of IκB kinase (IKK), Akt, and extracellular signal-regulated kinase (ERK) phosphorylation by BCR cross-linking in these cells. Furthermore, we show that CLL cells with high levels of LCK expression have higher levels of BCR-mediated IKK, Akt, and ERK phosphorylation as well as cell survival than CLL cells with low levels of LCK expression. We also show that treatment of CLL cells with Lck-i inhibits BCR cross-linking-induced cell survival. Taken together, these data show a major role for LCK in proximal and distal BCR-mediated signaling in CLL cells and suggest that LCK expression is important in the pathogenesis of this disease. On a clinical level, these studies advocate the use of specific LCK inhibitors in the treatment of progressive CLL.

ABT-737 resistance in B-cells isolated from chronic lymphocytic leukemia patients and leukemia cell lines is overcome by the pleiotropic kinase inhibitor quercetin through Mcl-1 down-regulation

Chronic lymphocytic leukemia (CLL) is the most frequent form of leukemia in adult population and despite numerous studies, it is considered an incurable disease. Since CLL is characterized by overexpression of pro-survival Bcl-2 family members, treatments with their antagonists, such as ABT-737, represent a promising new therapeutic strategy. ABT-737 is a BH3 mimetic agent which binds Bcl-2, Bcl-XL and Bcl-w with high affinity, while weakly interacts with Mcl-1 and Bfl-1. Previous studies demonstrated that quercetin, a flavonoid naturally present in food and beverages, was able to sensitize B-cells isolated from CLL patients to apoptosis when associated with death ligands or fludarabine, through a mechanism involving Mcl-1 down-regulation. Here, we report that the association between ABT-737 and quercetin synergistically induces apoptosis in B-cells and in five leukemic cell lines (Combination Index <1). Peripheral blood mononuclear cell from healthy donors were not affected by quercetin treatment. The molecular pathways triggered by quercetin have been investigated in HPB-ALL cells, characterized by the highest resistance to both ABT-737 and quercetin when applied as single molecules, but highly sensitivity to the co-treatment. In this cell line, quercetin down-regulated Mcl-1 through the inhibition of PI3K/Akt signaling pathway, leading to Mcl-1 instability. The same mechanism was confirmed in B-cells. These results may open new clinical perspectives based on a translational approach in CLL therapy.

Biological functions of ecto-enzymes in regulating extracellular adenosine levels in neoplastic and inflammatory disease states

When present in the extracellular environment, the nucleoside adenosine protects cells and tissues from excessive inflammation and immune-mediated damage while promoting healing processes. This role has been highlighted experimentally using distinct disease models, including those of colitis, diabetes, asthma, sepsis, and ischemic injury. Adenosine also suppresses immune responses, as in the tumor microenvironment, assisting immune evasion while promoting angiogenesis. The mechanisms involved in adenosine signaling are addressed elsewhere in this issue. Here, the authors specifically address the generation of adenosine from extracellular nucleotides. This process is catalyzed by a series of plasma membrane ectonucleotidases, with the focus in this article on members of the CD39, CD73, and CD38 families and on their role in inflammatory and neoplastic hematological diseases. Pharmacological modulation of adenosine generation by drugs that either have or modulate ectonucleotidase function might be exploited to treat these diverse conditions.

Integrated mutational and cytogenetic analysis identifies new prognostic subgroups in chronic lymphocytic leukemia

The identification of new genetic lesions in chronic lymphocytic leukemia (CLL) prompts a comprehensive and dynamic prognostic algorithm including gene mutations and chromosomal abnormalities and their changes during clonal evolution. By integrating mutational and cytogenetic analysis in 1274 CLL samples and using both a training-validation and a time-dependent design, 4 CLL subgroups were hierarchically classified: (1) high-risk, harboring TP53 and/or BIRC3 abnormalities (10-year survival: 29%); (2) intermediate-risk, harboring NOTCH1 and/or SF3B1 mutations and/or del11q22-q23 (10-year survival: 37%); (3) low-risk, harboring +12 or a normal genetics (10-year survival: 57%); and (4) very low-risk, harboring del13q14 only, whose 10-year survival (69.3%) did not significantly differ from a matched general population. This integrated mutational and cytogenetic model independently predicted survival, improved CLL prognostication accuracy compared with FISH karyotype (P < .0001), and was externally validated in an independent CLL cohort. Clonal evolution from lower to higher risk implicated the emergence of NOTCH1, SF3B1, and BIRC3 abnormalities in addition to TP53 and 11q22-q23 lesions. By taking into account clonal evolution through time-dependent analysis, the genetic model maintained its prognostic relevance at any time from diagnosis. These findings may have relevant implications for the design of clinical trials aimed at assessing the use of mutational profiling to inform therapeutic decisions.

Acadesine for patients with relapsed/refractory chronic lymphocytic leukemia (CLL): a multicenter phase I/II study

Purpose

Acadesine has shown in vitro to selectively induce apoptosis in B cells from chronic lymphocytic leukemia (CLL) patients. We conducted a phase I/II open-label clinical study, to determine the safety and tolerability of acadesine given intravenously as a 4-h infusion to CLL patients.

Methods

Patient population included CLL patients with relapsed/refractory disease who had received one or more prior lines of treatment including either a fludarabine or an alkylator-based regimen. Twenty-four patients were included: eighteen in Part I treated at single doses of 50–315 mg/kg, and six in Part II, three with two doses at 210 mg/kg and three with five doses at 210 mg/kg.

Results

A manageable and predictable safety profile was demonstrated for acadesine at single doses between 50 and 210 mg/kg; 210 mg/kg was the maximum tolerated dose (MTD) and optimal biological dose (OBD). Grade ≥2 hyperuricemia occurred commonly but was not clinically significant and resolved with the administration of prophylactic allopurinol. Other adverse events included transient anemia and/or thrombocytopenia (not clinically significant), renal impairment, and transient infusion-related hypotension (clinically significant). Trends of efficacy such as a reduction of peripheral CLL cells and reduction in lymphadenopathy were observed; however, the results were variable due to the small population and the range of doses tested.

Conclusions

A MTD of 210 mg/kg was established with single acadesine dose. Multiple dose administrations at the OBD were tested with an acceptable safety profile, showing that acadesine might be a valuable agent for the treatment of relapsed/refractory CLL patients.

A Japanese case of chronic lymphocytic leukemia with t (1;6)

Chronic lymphocytic leukemia (CLL) rarely exhibits an aggressive clinical course and its patients often have chromosomal deletions or additions. Furthermore, reciprocal translocations are barely observed in CLL. There have only been a few reports of CLL with t(1;6), and here we report the first Asian case of CLL with reciprocal translocation t(1;6). Since our case and previously reported CLL patients with t(1;6) consistently showed aggressive clinical course, t(1;6) may define a distinct type of CLL.

The role of FISH in hematologic cancer

SUMMARY Cytogenetic analysis is now considered a mandatory investigation in the diagnostic work-up of hematologic malignancies. Recurring structural aberrations serve as powerful markers not only for diagnosis and prognosis of these conditions, but also guide the selection of targeted drugs for personalized oncology. The FISH approach is established as an indispensable tool to complement conventional cytogenetics, in addition to basic and clinical research applications. FISH is used to identify specific chromosomal aberrations through the detection of target DNA sequences by fluorescently labeled DNA probes. Multicolor FISH analysis allows the accurate identification of recurring translocations in neoplastic cells by means of genomic probes that flank the breakpoints. This review summarizes the panel of FISH probes for selection and the current utilization of these FISH techniques in unraveling chromosomal aberrations. The niche of FISH analysis is also highlighted. Variant signal patterns of the clinically useful FISH probes for hematologic oncology illustrated here provide useful interpretative reference for molecular pathology laboratories. In addition, the recent application of FISH tests in contributing information on drug targets at the genomic level to support personalized oncology will also be discussed.

Therapeutic advancement of chronic lymphocytic leukemia

Despite the combinations of chemotherapy with monoclonal antibodies have further improved response rates, chronic lymphocytic leukemia (CLL) remains an incurable disease with an extremely variable course. This article reviews the ongoing clinical advances in the treatment of CLL in both previously untreated and relapsed disease and focuses on the benefit of different therapeutic strategies, the most effective therapy combinations and the potential activity of novel agents. Novel agents and combination therapies have been investigated by several studies in both the upfront and relapsed setting, particularly for patients with 17p deletion, TP53 mutation and fludarabine-refractory CLL. While these agents and combination therapies have improved initial response rates, ongoing studies are continued to determine and improve the efficacy and safety. Despite advancements in the treatment of CLL have led to high response rates, allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only curative option and reduced-intensity conditioning (RIC) allo-HSCT must be strongly considered whenever feasible. As such, ongoing studies of these agents and other novel approaches in clinical development are needed to expand and improve treatment options for CLL patients.

Chronic lymphocytic leukemia in African Americans

Chronic lymphocytic leukemia (CLL) is the most prevalent leukemia in the United States with almost 4390 attributable deaths per year. Epidemiologic data compiled by the Surveillance, Epidemiology and End Results (SEER) program identifies important differences in incidence and survival for African Americans with CLL. Although the incidence of CLL is lower among African Americans than among Caucasians (4.6 and 6.2 per 100 000 men, respectively), age-adjusted survival is inferior. African American patients with CLL are almost twice as likely to die from a CLL-related complication in the first 5 years after diagnosis as are Caucasian patients with CLL. The biologic basis for these observations is almost entirely unexplored, and a comprehensive clinical analysis of African American patients with CLL is lacking. This is the subject of the present review.

Single nucleotide polymorphisms and inherited risk of chronic lymphocytic leukemia among African Americans

The incidence of chronic lymphocytic leukemia (CLL) is significantly lower in African Americans than whites, but overall survival is inferior. The biologic basis for these observations remains unexplored. We hypothesized that germline genetic predispositions differ between African Americans and whites with CLL and yield inferior clinical outcomes among African Americans. We examined a discovery cohort of 42 African American CLL patients ascertained at Duke University and found that the risk allele frequency of most single nucleotide polymorphisms known to confer risk of development for CLL is significantly lower among African Americans than whites. We then confirmed our results in a distinct cohort of 68 African American patients ascertained by the CLL Research Consortium. These results provide the first evidence supporting differential genetic risk for CLL between African Americans compared with whites. A fuller understanding of differential genetic risk may improve prognostication and therapeutic decision making for all CLL patients.

Search for an aetiological virus candidate in chronic lymphocytic leukaemia by extensive transcriptome analysis

As an approach to determining the aetiology of chronic lymphocytic leukaemia (CLL), we searched for a virus expressed in human CLL B‐cells by combining high‐throughput sequencing and digital subtraction. Pooled B‐cell mRNA transcriptomes from five CLL patients and five healthy donors were sequenced with 454 Life Sciences technology. Human reads were excluded by BLAST (Basic Local Alignment Search Tool) and BLAT (BLAST‐like alignment tool) searches. Remaining reads were screened with BLAST against viral databases. Purified B‐cells from two CLL patients, with and without stimulation by phorbol‐esters, were sequenced using Illumina technology to achieve depth of sequencing. Burrows‐Wheeler Aligner mapping and BLAST searches were used for the Illumina data. Pyrosequencing resulted in about 400 000 reads per sample. No viral candidate could be found. Illumina single‐end sequencing for 115 cycles yielded an average of 26 ± 2·5 million filtered reads per sample, of which 2·2 ± 0·6 million remained unmapped to human references. BLAST searches of these reads against viral and human databases assigned nine reads to an Epstein‐Barr virus origin, in one sample following phorbol‐ester stimulation. Other reads showing a putative viral origin were dismissed after further analysis. Despite an in‐depth analysis of the CLL transcriptome reaching more than 100 million sequences, we have not found evidence for a putative viral candidate in CLL.

Translocation of nucleoside analogs across the plasma membrane in hematologic malignancies

Nucleoside analogs are currently used in the treatment of various hematologic malignancies due to their ability to induce apoptosis of lymphoid cells. For nucleoside-derived drugs to exert their action, they must enter cells via nucleoside transporters from two gene families, SLC28 and SLC29 (CNT and ENT, respectively). Once inside the cell, these drugs must be phosphorylated to their active forms. In contrast, some members of the ATP-binding cassette (ABC) protein family have been identified as responsible for the efflux of the phosphorylated forms of these nucleoside-derived drugs. Here, we review the main nucleoside analogs used in hematologic malignancies and focus especially on those that are currently used in chronic lymphocytic leukemia (CLL). Moreover, we discuss the pharmacological profile of the nucleoside transporters, which determines the bioavailability of and cell sensitivity to these nucleoside-derived drugs. We also discuss the expression of nucleoside transporters and their activities in CLL as well as the possibility of modulating these transporter activities as a means of modulating intracellular drug availability and, consequently, responsiveness to therapy.

Present status and perspectives in functional analysis of p53 in chronic lymphocytic leukemia

Aberrations of TP53 (mutations and/or deletions) are associated with a dismal prognosis in chronic lymphocytic leukemia (CLL). Complete loss of ATM is another mechanism of failed DNA damage response and also associated with poorer prognosis in CLL. However, p53 dysfunction may arise through alternative mechanisms unrelated to structural aberrations (deletion and/or mutation) of TP53 or ATM, and thus be undetectable by traditional DNA-directed approaches (fluorescence in situ hybridization [FISH], sequencing, karyotyping). In order to address the latter changes, and also to better understand the consequences of TP53/ATM aberrations, p53 functional assays have recently been developed. The purpose of dynamic assessment of p53 response in CLL is to carry out a comprehensive analysis of all mechanisms causing p53-deficient phenotype, including those unrelated to genomic aberrations of TP53 and ATM. The present review focuses on the current knowledge of p53 function assays in CLL, including important features such as technical issues, correlation with structural aberrations and clinical value.

Mutations of NOTCH1 are an independent predictor of survival in chronic lymphocytic leukemia

Analysis of the chronic lymphocytic leukemia (CLL) coding genome has recently disclosed that the NOTCH1 proto-oncogene is recurrently mutated at CLL presentation. Here, we assessed the prognostic role of NOTCH1 mutations in CLL. Two series of newly diagnosed CLL were used as training (n = 309) and validation (n = 230) cohorts. NOTCH1 mutations occurred in 11.0% and 11.3% CLL of the training and validation series, respectively. In the training series, NOTCH1 mutations led to a 3.77-fold increase in the hazard of death and to shorter overall survival (OS; P < .001). Multivariate analysis selected NOTCH1 mutations as an independent predictor of OS after controlling for confounding clinical and biologic variables. The independent prognostic value of NOTCH1 mutations was externally confirmed in the validation series. The poor prognosis conferred by NOTCH1 mutations was attributable, at least in part, to shorter treatment-free survival and higher risk of Richter transformation. Although NOTCH1 mutated patients were devoid of TP53 disruption in more than 90% cases in both training and validation series, the OS predicted by NOTCH1 mutations was similar to that of TP53 mutated/deleted CLL. NOTCH1 mutations are an independent predictor of CLL OS, tend to be mutually exclusive with TP53 abnormalities, and identify cases with a dismal prognosis.

CD73-generated extracellular adenosine in chronic lymphocytic leukemia creates local conditions counteracting drug-induced cell death

Extracellular adenosine (ADO), generated from ATP or ADP through the concerted action of the ectoenzymes CD39 and CD73, elicits autocrine and paracrine effects mediated by type 1 purinergic receptors. We have tested whether the expression of CD39 and CD73 by chronic lymphocytic leukemia (CLL) cells activates an adenosinergic axis affecting growth and survival. By immunohistochemistry, CD39 is widely expressed in CLL lymph nodes, whereas CD73 is restricted to proliferation centers. CD73 expression is highest on Ki-67(+) CLL cells, adjacent to T lymphocytes, and is further localized to perivascular areas. CD39(+)/CD73(+) CLL cells generate ADO from ADP in a time- and concentration-dependent manner. In peripheral blood, CD73 expression occurs in 97/299 (32%) CLL patients and pairs with CD38 and ZAP-70 expression. CD73-generated extracellular ADO activates type 1 purinergic A2A receptors that are constitutively expressed by CLL cells and that are further elevated in proliferating neoplastic cells. Activation of the ADO receptors increases cytoplasmic cAMP levels, inhibiting chemotaxis and limiting spontaneous drug-induced apoptosis of CLL cells. These data are consistent with the existence of an autocrine adenosinergic loop, and support engraftment of leukemic cells in growth-favorable niches, while simultaneously protecting from the action of chemotherapeutic agents.

Single-agent rituximab in treatment-refractory or poor prognosis patients with chronic lymphocytic leukemia

OBJECTIVE

Rituximab in combination with fludarabine and cyclophosphamide has significantly improved outcomes for patients with chronic lymphocytic leukemia (CLL) and an improvement in overall survival has recently been shown for the first time in the history of CLL treatment. However, the chemotherapy portion of this regimen may be unsuitable for elderly patients or those with significant comorbidities. We investigated the safety and tolerability of single-agent rituximab in 23 consecutive patients presenting with CLL at a single institution.

RESEARCH DESIGN AND METHODS

Patients received eight cycles of weekly rituximab (375 mg/m(2) initially). Patients progressing on rituximab treatment could receive up to five further courses of single-agent rituximab in escalating doses up to 3 gm/m(2) per dose. Previously untreated and previously treated patients, including those refractory to fludarabine, were eligible for the study.

RESULTS

Single-agent rituximab was efficacious, even in patients with treatment-refractory or poor-prognosis CLL. The overall response rate was 90.9% with a CR rate of 63.6%. The median PFS was 28.5 months, and median duration of response was 26 months. Responses were seen regardless of prior treatment including in patients refractory to fludarabine. Especially encouraging results were seen in patients receiving rituximab maintenance therapy who had a median duration of response substantially longer than those who did not receive maintenance (35 months vs. 14 months, respectively).

CONCLUSIONS

Rituximab was well tolerated with no unexpected adverse events even at the highest dose. These results indicate that single-agent rituximab is effective and has a place in the treatment of CLL.

Use and costs of oral anticancer agents in the Netherlands in the period 2000-2008

PURPOSE

In recent years, the number of oral anticancer agents has increased substantially. Although these agents have quickly been incorporated in the treatment of a variety of malignancies, data on their incidence, prevalence and costs are lacking. The objective of the present study was to obtain insight into the use and the costs of oral anticancer agents (with Anatomical Therapeutic Chemical classification system (World Health Organisation) code L01) in the Netherlands between 2000 and 2008.

METHODS

Incidence and prevalence were determined using community pharmacy dispensing records obtained from the PHARMO Record Linkage System database. The data of costs were provided by the Genees- en hulpmiddelen Informatie Project of the Dutch Health Care Insurance Board (CVZ, Diemen, The Netherlands).

RESULTS

In the years 2000-2008, the use of oral anticancer agents has more than doubled from 64 to 140 users per 100 000 inhabitants. The increase is mainly caused by the prescription of capecitabine for various indications. There was a 50-fold rise in costs on oral anticancer agents from €2 m in 2000 to approximately €100 m in 2008. The share in the costs of tyrosine kinase inhibitors (TKIs) in 2008 was 67% (€70 m) with the oldest TKI, imatinib, having a share of more than 50% within the group of TKIs.

CONCLUSIONS

The increased use of oral anticancer agents is mainly due to the frequent prescription of capecitabine. The increased costs are caused by the registration of a variety of TKIs, in particular imatinib. The costs of new agents with an orphan drug status are very high as compared with those of capecitabine, a newer agent for which there are alternative treatment options.

Phase II study of cenersen, an antisense inhibitor of p53, in combination with fludarabine, cyclophosphamide and rituximab for high-risk chronic lymphocytic leukemia

Patients with chronic lymphocytic leukemia (CLL) with deletion or mutation of TP53 have exceedingly poor clinical outcomes. Cenersen, an oligonucleotide targeting TP53, has been shown to abrogate the activity of TP53 gain-of-function mutants and to increase sensitivity of lymphoma cells to cytotoxic chemotherapy in vitro. We combined cenersen with fludarabine, cyclophosphamide and rituximab (FCR) as treatment for patients with high-risk CLL. The purpose of this phase II study was to determine the overall response rate, response duration and toxicity of cenersen administered in combination with FCR. Twenty patients with relapsed or high-risk CLL were evaluated. Nineteen patients were previously treated. The complete response rate was 18%; the overall response rate was 53%. Median progression-free and overall survival was 5.3 and 10.6 months, respectively. The most common serious adverse events were neutropenia and thrombocytopenia. In this single arm phase II study, cenersen combined with FCR yielded clinical responses with acceptable toxicity in patients with high-risk CLL.

Ofatumumab: a novel anti-CD20 monoclonal antibody for treatment of refractory chronic lymphocytic leukemia

OBJECTIVE

To present the current clinical evidence on ofatumumab for use in refractory chronic lymphocytic leukemia (CLL).

DATA SOURCES

A literature search was performed using MEDLINE and PubMed (both 1966-May 2011), as well as the American Society of Hematology abstracts (2000-May 2011), using the primary search terms ofatumumab and HuMax-CD20.

STUDY SELECTION AND DATA EXTRACTION

Clinical studies and abstracts available in the English language, describing the pharmacology, pharmacokinetics, clinical activity, and safety of ofatumumab in CLL were included in this review.

DATA SYNTHESIS

Ofatumumab is a human immunoglobulin monoclonal antibody that binds to B-lymphocytes expressing CD-20 cell surface antigens. Ofatumumab was granted accelerated approval by the Food and Drug Administration in October 2009 for the treatment of CLL refractory to fludarabine and alemtuzumab. A Phase 1/2 trial has established the safety and tolerability of single-agent ofatumumab at an initial dose of 300 mg intravenously on week 1, followed by 2000 mg once weekly for 7 doses (weeks 2-8), followed by 2000 mg once every 4 weeks for 4 doses (weeks 9-12), for a total of 12 doses. The final analysis of a pivotal international multicenter trial has shown promising activity in patients with CLL refractory to fludarabine and alemtuzumab, demonstrating overall response rates of 44-51%, with prolonged progression-free and overall survival. Ofatumumab activity has also been shown in a variety of other malignant and nonmalignant conditions, including non-Hodgkin lymphoma, rheumatoid arthritis, and multiple sclerosis. The most common adverse effect is grade 1 and 2 infusion reactions. Other adverse effects include infection, neutropenia, anemia, rash, fever, and diarrhea.

CONCLUSIONS

Clinical evidence suggests that ofatumumab is an effective agent in patients with CLL refractory to fludarabine and alemtuzumab. Data are awaited comparing ofatumumab to other salvage regimens. Until results of head-to-head trials are conducted comparing ofatumumab to existing regimens, it cannot be said whether ofatumumab is more efficacious or tolerable than currently available therapies.

The cytotoxic activity of Aplidin in chronic lymphocytic leukemia (CLL) is mediated by a direct effect on leukemic cells and an indirect effect on monocyte-derived cells

Aplidin is a novel cyclic depsipeptide, currently in Phase II/III clinical trials for solid and hematologic malignancies. The aim of this study was to evaluate the effect of Aplidin in chronic lymphocytic leukemia (CLL), the most common leukemia in the adult. Although there have been considerable advances in the treatment of CLL over the last decade, drug resistance and immunosuppression limit the use of current therapy and warrant the development of novel agents. Here we report that Aplidin induced a dose- and time-dependent cytotoxicity on peripheral blood mononuclear cells (PBMC) from CLL patients. Interestingly, Aplidin effect was markedly higher on monocytes compared to T lymphocytes, NK cells or the malignant B-cell clone. Hence, we next evaluated Aplidin activity on nurse-like cells (NLC) which represent a cell subset differentiated from monocytes that favors leukemic cell progression through pro-survival signals. NLC were highly sensitive to Aplidin and, more importantly, their death indirectly decreased neoplasic clone viability. The mechanisms of Aplidin-induced cell death in monocytic cells involved activation of caspase-3 and subsequent PARP fragmentation, indicative of death via apoptosis. Aplidin also showed synergistic activity when combined with fludarabine or cyclophosphamide. Taken together, our results show that Aplidin affects the viability of leukemic cells in two different ways: inducing a direct effect on the malignant B-CLL clone; and indirectly, by modifying the microenvironment that allows tumor growth.

Safety and persistence of adoptively transferred autologous CD19-targeted T cells in patients with relapsed or chemotherapy refractory B-cell leukemias

We report the findings from the first 10 patients with chemotherapy-refractory chronic lymphocytic leukemia (CLL) or relapsed B-cell acute lymphoblastic leukemia (ALL) we have enrolled for treatment with autologous T cells modified to express 19-28z, a second-generation chimeric antigen (Ag) receptor specific to the B-cell lineage Ag CD19. Eight of the 9 treated patients tolerated 19-28z(+) T-cell infusions well. Three of 4 evaluable patients with bulky CLL who received prior conditioning with cyclophosphamide exhibited either a significant reduction or a mixed response in lymphadenopathy without concomitant development of B-cell aplasia. In contrast, one patient with relapsed ALL who was treated in remission with a similar T-cell dose developed a predicted B-cell aplasia. The short-term persistence of infused T cells was enhanced by prior cyclophosphamide administration and inversely proportional to the peripheral blood tumor burden. Further analyses showed rapid trafficking of modified T cells to tumor and retained ex vivo cytotoxic potential of CD19-targeted T cells retrieved 8 days after infusion. We conclude that this adoptive T-cell approach is promising and more likely to show clinical benefit in the setting of prior conditioning chemotherapy and low tumor burden or minimal residual disease. These studies are registered at www.clinicaltrials.org as #NCT00466531 (CLL protocol) and #NCT01044069 (B-ALL protocol).

Increased metastasis of malignant fibrous histiocytoma in patients with chronic lymphocytic leukemia and non-hodgkin lymphoma

OBJECTIVE

To further understand the characteristics and behavior of malignant fibrous histiocytoma (MFH) in the clinical setting of chronic lymphocytic leukemia (CLL) or non-Hodgkin lymphoma (NHL).

PATIENTS AND METHODS

The patient database of MHF diagnosed at our institution from January 1, 1976, to December 31, 2008, was reviewed. For each MFH case with prior NHL or CLL, 3 matched controls from the same cohort without prior CLL or NHL were randomly selected. A retrospective chart review collected patient data, including sex; age; pathologic confirmation of MFH; tumor grade, size, and location; time since MFH diagnosis; history of chemotherapy or irradiation; treatment of MFH; recurrence; metastasis; and death. The Kaplan-Meier method was used to estimate overall survival, survival free of recurrence, and survival free of metastasis. Cox proportional hazards models were fit to evaluate associations between case status and outcomes.

RESULTS

Fifteen MFH cases with prior NHL or CLL were identified. Cases had frequent bone (n=7 [47%]) and cutaneous (n=5 [33%]) involvement. Five cases (33%) had previous irradiation, 6 (40%) had metastases, and 4 (27%) had recurrence. Overall survival and survival free of recurrence were not significantly different between the cases and controls (5-year overall survival, 49.9% and 58.7%; 12-month survival free of recurrence, 79.4% and 90.3%). However, cases were significantly more likely than controls to have metastasis (hazard ratio, 3.79; 95% confidence interval, 1.22-11.79; P=.02). In addition, survival free of metastasis at 12 months was 65.2% and 90.7%, respectively.

CONCLUSION

In the presence of CLL or NHL, MFH seems to behave more aggressively, suggested by the increased likelihood of metastases compared with controls without prior CLL or NHL. However, overall survival does not appear to be worse in cases of MFH and CLL or NHL than in MFH alone.

The novel member of the BCL2 gene family, BCL2L12, is substantially elevated in chronic lymphocytic leukemia patients, supporting its value as a significant biomarker

BCL2L12 is a recently identified gene belonging to the BCL2 family, members of which are implicated in hematologic malignancies, including chronic lymphocytic leukemia (CLL). The aim of this study was to analyze the mRNA expression of the novel apoptosis-related gene BCL2L12 in patients with CLL and to examine its prognostic and predictive value and potential clinical application as a novel molecular biomarker for CLL. For this purpose, total RNA was isolated from peripheral blood of 65 CLL patients and 23 healthy donors. An ultrasensitive quantitative real-time polymerase chain reaction methodology for BCL2L12 and BCL2 mRNA quantification was developed using SYBR Green chemistry. After preparing cDNA by reverse transcription, relative quantification analysis was performed using the comparative C(T) (2(-ΔΔCT)) method. Furthermore, analysis of IGHV mutational status, CD38 expression, and detection of early apoptosis by double staining with Annexin V-FITC and propidium iodide were performed. According to our findings, BCL2L12 mRNA expression is significantly higher in CLL patients than in healthy donors. Receiver operating characteristic analysis demonstrated that BCL2L12 expression had significant discriminatory value, distinguishing very efficiently CLL patients from the non-leukemic population. Moreover, BCL2L12 expression predicts the presence of CLL, as demonstrated by both univariate and multivariate logistic regression analyses. Finally, high BCL2L12 mRNA levels are associated with advanced clinical stage and predict shorter overall survival in CLL patients.

Autologous stem cell transplantation as a first-line treatment strategy for chronic lymphocytic leukemia: a multicenter, randomized, controlled trial from the SFGM-TC and GFLLC

Long-term responses have been reported after autologous stem cell transplantation (ASCT) for chronic lymphocytic leukemia (CLL). We conducted a prospective, randomized trial of ASCT in previously untreated CLL patients. We enrolled 241 patients < 66 years of age with Binet stage B or C CLL. They received 3 courses of mini-CHOP (cyclophosphamide, hydroxydaunorubicin, oncovin, and prednisone/prednisolone) and then 3 courses of fludarabine. Patients in complete response (CR) were then randomized to ASCT or observation, whereas the other patients were randomized to dexamethasone, high-dose aracytin, cisplatin (DHAP) salvage followed by either ASCT or 3 courses of fludarabine plus cyclophosphamide (FC). The primary end point was event-free survival (EFS). After up-front treatment, 105 patients entered CR and were randomized between ASCT (n = 52) and observation (n = 53); their respective 3-year EFS rates were 79.8% and 35.5%; the adjusted hazard ratio was 0.3 (95% CI: 0.1-0.7; P = .003). Ninety-four patients who did not enter CR were randomized between ASCT (n = 46) and FC (n = 48); their respective 3-year EFS rates were 48.9% and 44.4%, respectively; the adjusted hazard ratio was 1.7 (95% CI: 0.9-3.2; P = .13). No difference in overall survival was found between the 2 response subgroups. In young CLL patients in CR, ASCT consolidation markedly delayed disease progression. No difference was observed between ASCT and FC in patients requiring DHAP salvage.

Multiplex ligation-dependent probe amplification and fluorescence in situ hybridization to detect chromosomal abnormalities in chronic lymphocytic leukemia: a comparative study

Chronic lymphocytic leukemia (CLL) is a clinically heterogeneous disease characterized by recurrent chromosomal aberrations of prognostic significance. We aimed to evaluate the potential of the multiplex ligation-dependent probe amplification (MLPA) assay to detect genomic alterations in CLL. Highly purified (>90%) peripheral mononuclear CD19+ cell populations from 100 untreated CLL patients (pts) in early stage disease (Binet stage A) were included in this study. All samples were investigated by fluorescence in situ hybridization (FISH) for the presence of trisomy 12 and 17p13.1, 11q22.3, and 13q14.3 deletions. For MPLA analysis, DNA was amplified by means of two commercially available probes sets allowing the simultaneous screening of 56 genomic sequences. Overall, a high degree of concordance (95%) between MPLA and FISH results was found, if the abnormal clone was present in more than 30% of the leukemic cell population. The use of multiple MPLA probes allowed the fine-mapping of the 13q14 deletion and the identification of intragenic or small alterations undetected by FISH. Moreover, additional alterations in 2p24 (MYCN) (3 pts), 8q24 (MYC) (1 pt), 9p21 (CDKN2A2B) (1 pt), 1q21 (LMNA) (1 pt), and 6q25-26 (1 pt) regions not covered by a standard FISH assay were detected and all confirmed by FISH. Our data extend previously limited evidence that MLPA may represent a useful technique for the characterization of well-known lesions as well as the investigation of additional genomic changes in CLL.

OSU-DY7, a novel D-tyrosinol derivative, mediates cytotoxicity in chronic lymphocytic leukaemia and Burkitt lymphoma through p38 mitogen-activated protein kinase pathway

Drug resistance and associated immune deregulation limit use of current therapies in chronic lymphocytic leukaemia (CLL), thus warranting alternative therapy development. Herein we demonstrate that OSU-DY7, a novel D-tyrosinol derivative targeting p38 mitogen-activated protein kinase (MAPK), mediates cytotoxicity in lymphocytic cell lines representing CLL (MEC-1), acute lymphoblastic leukaemia (697 cells), Burkitt lymphoma (Raji and Ramos) and primary B cells from CLL patients in a dose- and time-dependent manner. The OSU-DY7-induced cytotoxicity is dependent on caspase activation, as evidenced by induction of caspase-3 activation and poly (ADP-ribose) polymerase (PARP) cleavage and rescue of cytotoxicity by Z-VAD-FMK. Interestingly, OSU-DY7-induced cytotoxicity is mediated through activation of p38 MAPK, as evidenced by increased phosphorylation of p38 MAPK and downstream target protein MAPKAPK2. Pretreatment of B-CLL cells with SB202190, a specific p38 MAPK inhibitor, results in decreased MAPKAPK2 protein level with concomitant rescue of the cells from OSU-DY7-mediated cytotoxicity. Furthermore, OSU-DY7-induced cytotoxicity is associated with down regulation of p38 MAPK target BIRC5, that is rescued at protein and mRNA levels by SB202190. This study provides evidence for a role of OSU-DY7 in p38 MAPK activation and BIRC5 down regulation associated with apoptosis in B lymphocytic cells, thus warranting development of this alternative therapy for lymphoid malignancies.

An observational study of outcomes after initial infused therapy in Medicare patients diagnosed with chronic lymphocytic leukemia

The study goal was to characterize older chronic lymphocytic leukemia (CLL) patients and to evaluate outcomes in those patients who initiated infused therapy. Patients 66 years of age and older in the Surveillance, Epidemiology, and End Results (SEER) program with a CLL diagnosis were matched to their Medicare Part A and Part B claims for long-term follow-up. Treatment patterns, survival after initiation of infused therapy, and both hematologic and hospitalization outcomes were assessed. There were 6433 CLL patients identified, and 2040 received infused therapy. Treated patients were categorized as receiving rituximab monotherapy (16%), rituximab plus chemotherapy (14%), and chemotherapy alone (70%) based on the initial 60 days after infusion. Rituximab plus chemotherapy compared with chemotherapy alone was associated with a 25% lower risk of overall mortality (95% confidence interval, 9%-38%). Restricting to patients age 70 years and older did not change the risk reduction for rituximab plus chemotherapy. Hematologic interventions were more common with rituximab plus chemotherapy compared with chemotherapy alone, but there was no difference in all-cause hospitalizations. These analyses, based on observational data, suggest that the benefits of initial therapy with rituximab in a heterogeneous group of older CLL patients are comparable with those demonstrated in younger patients.