Clinical implications of the molecular genetics of chronic lymphocytic leukemia

Absence of BTK, BCL2, and PLCG2 Mutations in Chronic Lymphocytic Leukemia Relapsing after First-Line Treatment with Fixed-Duration Ibrutinib plus Venetoclax

PURPOSE

Mutations in BTK, PLCG2, and BCL2 have been reported in patients with progressive disease (PD) on continuous single-agent BTK or BCL2 inhibitor treatment. We tested for these mutations in samples from patients with PD after completion of first-line treatment with fixed-duration ibrutinib plus venetoclax for chronic lymphocytic leukemia (CLL) in the phase II CAPTIVATE study.

PATIENTS AND METHODS

A total of 191 patients completed fixed-duration ibrutinib plus venetoclax (three cycles of ibrutinib then 12-13 cycles of ibrutinib plus venetoclax). Genomic risk features [del(11q), del(13q), del(17p), trisomy 12, complex karyotype, unmutated IGHV, TP53 mutated] and mutations in genes recurrently mutated in CLL (ATM, BIRC3, BRAF, CHD2, EZH2, FBXW7, MYD88, NOTCH1, POT1, RPS15, SF3B1, XPO1) were assessed at baseline in patients with and without PD at data cutoff; gene variants and resistance-associated mutations in BTK, PLCG2, or BCL2 were evaluated at PD.

RESULTS

Of 191 patients completing fixed-duration ibrutinib plus venetoclax, with median follow-up of 38.9 months, 29 (15%) developed PD. No baseline risk feature or gene mutation was significantly associated with development of PD. No previously reported resistance-associated mutations in BTK, PLCG2, or BCL2 were detected at PD in 25 patients with available samples. Of the 29 patients with PD, 19 have required retreatment (single-agent ibrutinib, n = 16, or ibrutinib plus venetoclax, n = 3); 17 achieved partial response or better, 1 achieved stable disease, and 1 is pending response assessment.

CONCLUSIONS

First-line fixed-duration combination treatment with ibrutinib plus venetoclax may mitigate development of resistance mechanisms associated with continuous single-agent targeted therapies, allowing for effective retreatment. See related commentary by Al-Sawaf and Davids, p. 471.

Implementation of International Prognostic Index with flow cytometry immunophenotyping for better risk stratification of chronic lymphocytic leukemia

BACKGROUND

Current chronic lymphocytic leukemia (CLL) International Prognostic Index (IPI) stratifies patients based on clinical, molecular, and biochemical features; however, B-cell markers also influence CLL outcomes. Here, prognostic roles of CD11c, CD38, and CD49d were first evaluated, and then an immunophenotypic score was combined with CLL-IPI for risk stratification of CLL patients.

METHODS

A total of 171 CLL subjects were included, and surface marker expression was assessed by flow cytometry. Levels ≥30% were chosen as cut-off of positivity to a marker; then values of 1 (for CD11c and CD38) or 3 (for CD49d) were assigned and scores determined for each patient's clone immunophenotype.

RESULTS

CD49d positivity was significantly associated with simultaneous expression of CD11c and/or CD38, unmutated IGHV status, and higher β2-microglobulin levels compared to those with CD49d negativity. Moreover, CD49d⁺ patients experienced a shorter progression-free survival and time to treatment. When the immunophenotypic score was combined with CLL-IPI, patients with high-risk immunophenotype had a significantly lower time-to-treatment regardless CLL-IPI.

CONCLUSIONS

Our results suggested clinical utility of an integrated prognostic score for better risk stratification of CLL patients. These results require further validation in prospective larger studies.

Up to 6.5 years (median 4 years) of follow-up of first-line ibrutinib in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma and high-risk genomic features: integrated analysis of two phase 3 studies

Genomic abnormalities, including del(17p)/TP53 mutation, del(11q), unmutated IGHV, and mutations in BIRC3, NOTCH1, SF3B1, and XPO1 predict poor outcomes with chemoimmunotherapy in chronic lymphocytic leukemia. To better understand the impact of these high-risk genomic features on outcomes with first-line ibrutinib-based therapy, we performed pooled analysis of two phase 3 studies with 498 patients randomized to receive ibrutinib- or chlorambucil-based therapy with median follow-up of 49.1 months. Ibrutinib-based therapy improved overall response rates (ORRs), complete response rates, and progression-free survival (PFS) versus chlorambucil-based therapy across all subgroups. In ibrutinib-randomized patients with versus without specified genomic features, ORR and PFS were comparable across subgroups. PFS hazard ratio (95% CI) for del(17p)/TP53 mutated/BIRC3 mutated: 1.05 (0.54-2.04); del(17p)/TP53 mutation, del(11q), and/or unmutated IGHV: 1.11 (0.69-1.77); unmutated IGHV: 1.79 (0.99-3.24); and NOTCH1 mutated 1.05 (0.65-1.69). This integrated analysis demonstrated efficacy of first-line ibrutinib-based treatment irrespective of cytogenetic and mutational risk features.Registered at ClinicalTrials.gov (NCT01722487 and NCT02264574).

Optimal Management of Chronic Lymphocytic Leukemia and Economic Constraints

ABSTRACT

In this article, we carry out an overview on the management options available for chronic lymphocytic leukemia (CLL) patients and discuss possible treatment decisions, taking into account the issue of sustainability and availability. Targeted agents have shown to be superior compared with chemoimmunotherapy (CIT) in terms of progression-free survival in high-risk CLL. In the majority of studies, however, continuous treatment was compared with fixed-duration CIT and no overall survival or progression-free survival-2 (time from randomization to second progression or death) advantage could be documented. Meanwhile, a substantial financial burden on both patients and payers has raised issues about affordability and adherence to treatment. Therefore, value-based pricing of new drugs has been used to set up price negotiation policies in several countries, and fixed-duration therapy has shown to be less costly than continuous treatment. Thus, CIT continues to have a role in the treatment of CLL patients with a favorable genetic profile, that is, with a mutated IGHV gene profile and a wild-type TP53. Targeted treatment represents the preferred choice in patients with an unmutated IGHV gene configuration and/or a TP53 disruption, provided that adherence to treatment is guaranteed and bearing in mind that should costly drugs not be available for frontline treatment, new agents can be very effective as first salvage treatment.

Prognostic significance of translocations in the presence of mutated IGHV and of cytogenetic complexity at diagnosis of chronic lymphocytic leukemia

Mutations of the IGH variable region in patients with chronic lymphocytic leukemia (CLL) are associated with a favorable prognosis. Cytogenetic complexity (>3 unrelated aberrations) and translocations have been associated with an unfavorable prognosis. While mutational status of IGHV is stable, cytogenetic aberrations frequently evolve. However, the relationships of these features as prognosticators at diagnosis are unknown. We examined the CpG-stimulated metaphase cytogenetic features detected within one year of diagnosis of CLL and correlated these features with outcome and other clinical features including IGHV. Of 329 untreated patients, 53 (16.1%) had a complex karyotype (16.1%), and 85 (25.8%) had a translocation. Median time to first treatment (TFT) was 47 months. In univariable analyses, significant risk factors for shorter TFT (p3.5, log-transformed WBC, unmutated IGHV, complex karyotype, translocation, and FISH for trisomy 8, del(11q) and del(17p). In multivariable analysis, there was significant effect modification of IGHV status on the relationship between translocation and TFT (p=0.002). In IGHV mutated patients, those with a translocation had over 3.5 times higher risk of starting treatment than those without a translocation (p.

AID in Chronic Lymphocytic Leukemia: Induction and Action During Disease Progression

The enzyme activation-induced cytidine deaminase (AID) initiates somatic hypermutation (SHM) and class switch recombination (CSR) of immunoglobulin (Ig) genes, critical actions for an effective adaptive immune response. However, in addition to the benefits generated by its physiological roles, AID is an etiological factor for the development of human and murine leukemias and lymphomas. This review highlights the pathological role of AID and the consequences of its actions on the development, progression, and therapeutic refractoriness of chronic lymphocytic leukemia (CLL) as a model disease for mature lymphoid malignancies. First, we summarize pertinent aspects of the expression and function of AID in normal B lymphocytes. Then, we assess putative causes for AID expression in leukemic cells emphasizing the role of an activated microenvironment. Thirdly, we discuss the role of AID in lymphomagenesis, in light of recent data obtained by NGS analyses on the genomic landscape of leukemia and lymphomas, concentrating on the frequency of AID signatures in these cancers and correlating previously described tumor-gene drivers with the presence of AID off-target mutations. Finally, we discuss how these changes could affect tumor suppressor and proto-oncogene targets and how they could be associated with disease progression. Collectively, we hope that these sections will help to better understand the complex paradox between the physiological role of AID in adaptive immunity and its potential causative activity in B-cell malignancies.

A 3' tRNA-derived fragment produced by tRNALeuAAG and tRNALeuTAG is associated with poor prognosis in B-cell chronic lymphocytic leukemia, independently of classical prognostic factors

OBJECTIVE

3' tRNA-derived fragments (3' tRFs) are important epigenetic regulators in normal and pathological conditions. In this study, we aimed to explore the potential value of a 3' tRF as a prognostic and/or screening biomarker for B-cell chronic lymphocytic leukemia (B-CLL).

METHODS

Publicly available next-generation sequencing data from 20 B-CLL cases were analyzed, followed by prediction of targets of the most abundantly and ubiquitously expressed 3' tRFs, leading to selection of tRF-Leu^AAG/TAG . PBMCs were isolated from blood samples of 91 B-CLL patients and 43 non-leukemic donors, followed by total RNA extraction, in-vitro polyadenylation, and first-strand cDNA synthesis. Next, a real-time quantitative PCR (qPCR) assay was developed for the accurate quantification of tRF-Leu^AAG/TAG and applied in all samples, prior to biostatistical analysis.

RESULTS

High tRF-Leu^AAG/TAG levels are associated with inferior overall survival (OS) of B-CLL patients. The unfavorable significance of tRF-Leu^AAG/TAG was independent of established prognostic factors in B-CLL. Stratified Kaplan-Meier OS analysis uncovered the unfavorable prognostic role of high tRF-Leu^AAG/TAG levels for patients in Binet A or Rai I stage, negative CD38 expression, mutated, or unmutated IGHV genomic locus.

CONCLUSION

Our approach revealed the independent prognostic value of a particular 3' tRF, derived from tRNA^LeuAAG and tRNA^LeuTAG (tRF-Leu^AAG/TAG ) in B-CLL.

Genetic landscape of ultra-stable chronic lymphocytic leukemia patients

Background

Chronic lymphocytic leukemia (CLL) has a heterogeneous clinical course. Beside patients requiring immediate treatment, others show an initial indolent phase followed by progression and others do not progress for decades. The latter two subgroups usually display mutated IGHV genes and a favorable FISH profile.

Patients and methods

Patients with absence of disease progression for over 10 years (10-34) from diagnosis were defined as ultra-stable CLL (US-CLL). Forty US-CLL underwent extensive characterization including whole exome sequencing (WES), ultra-deep sequencing and copy number aberration (CNA) analysis to define their unexplored genetic landscape. Microarray analysis, comparing US-CLL with non-US-CLL with similar immunogenetic features (mutated IGHV/favorable FISH), was also carried out to recognize US-CLL at diagnosis.

Results

WES was carried out in 20 US-CLL and 84 non-silent somatic mutations in 78 genes were found. When re-tested in a validation cohort of 20 further US-CLL, no recurrent lesion was identified. No clonal mutations of NOTCH1, BIRC3, SF3B1 and TP53 were found, including ATM and other potential progression driving mutations. CNA analysis identified 31 lesions, none with known poor prognostic impact. No novel recurrent lesion was identified: most cases showed no lesions (38%) or an isolated del(13q) (31%). The expression of 6 genes, selected from a gene expression profile analysis by microarray and quantified by droplet digital PCR on a cohort of 79 CLL (58 US-CLL and 21 non-US-CLL), allowed to build a decision-tree capable of recognizing at diagnosis US-CLL patients.

Conclusions

The genetic landscape of US-CLL is characterized by the absence of known unfavorable driver mutations/CNA and of novel recurrent genetic lesions. Among CLL patients with favorable immunogenetics, a decision-tree based on the expression of 6 genes may identify at diagnosis patients who are likely to maintain an indolent disease for decades.

Chronic Myelogenous Leukemia Diagnosed in the Setting of Untreated Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma

Chronic myeloid leukemia (CML) is rarely reported to occur in treated chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). In this article, we report a woman in her 70s, diagnosed with CLL/SLL in 2000, untreated, who subsequently presented 12 years later with de novo CML, BCR-ABL1+. Her IGHV mutated CLL/SLL based on the initial sample in our laboratory showed homozygous and heterozygous 13q14.3 deletions, whereas her CML, at presentation, showed a 46,XX,t(9;22)(q34;q11.2)[7]/46,XX[18] karyotype with a p190 BCR-ABL1 transcript. The tumor burden of each clone varied with treatment, including when treated with dasatinib, used to target both clones. In addition, the cytogenetic abnormalities evolved over time and treatments and included acquisition of an extra chromosome 8 in the CML clone and a novel K1992T ATM missense mutation (47% allele frequency) in the CLL/SLL clone. The patient's last bone marrow biopsy, 5 years after her CML diagnosis and 17 years after the CLL/SLL diagnosis, showed residual CML with extensive involvement by CLL/SLL (80%). Cytogenetic studies showed a 46,XX karyotype, while FISH identified 13q14.3 deletion and the BCR-ABL1 translocation in the CLL/SLL and CML clones, respectively. To date, this is the fourth case of concurrent CML, BCR-ABL1+ arising in untreated CLL/SLL. Here we show dynamic variation in the size of the 2 clonal processes reflecting the variable responsiveness to specific therapies. In addition to the unusual BCR-ABL1+ p190 transcript in the patient's CML, a novel ATM K1992T mutation was identified in the CLL/SLL population.

Minimal Residual Disease in Chronic Lymphocytic Leukemia: A New Goal?

In chronic lymphocytic leukemia (CLL), there is a growing interest for minimal residual disease (MRD) monitoring, due to the availability of drug combinations capable of unprecedented complete clinical responses. The standardized and most commonly applied methods to assess MRD in CLL are based on flow cytometry (FCM) and, to a lesser extent, real-time quantitative PCR (RQ-PCR) with allele-specific oligonucleotide (ASO) primers of immunoglobulin heavy chain genes (IgH). Promising results are being obtained using droplet digital PCR (ddPCR) and next generation sequencing (NGS)-based approaches, with some advantages and a potential higher sensitivity compared to the standardized methodologies. Plasma cell-free DNA can also be explored as a more precise measure of residual disease from all different compartments, including the lymph nodes. From a clinical point of view, CLL MRD quantification has proven an independent prognostic marker of progression-free survival (PFS) and overall survival (OS) after chemoimmunotherapy as well as after allogeneic transplantation. In the era of mechanism-driven drugs, the paradigms of CLL treatment are being revolutionized, challenging the use of chemoimmunotherapy even in first-line. The continuous administration of ibrutinib single agent has led to prolonged PFS and OS in relapsed/refractory and treatment naïve CLL, including those with TP53 deletion/mutation or unmutated IGHV genes, though the clinical responses are rarely complete. More recently, chemo-free combinations of venetoclax+rituximab, venetoclax+obinutuzumab or ibrutinib+venetoclax have been shown capable of inducing undetectable MRD in the bone marrow, opening the way to protocols exploring a MRD-based duration of treatment, aiming at disease eradication. Thus, beside a durable disease control desirable particularly for older patients and/or for those with comorbidities, a MRD-negative complete remission is becoming a realistic prospect for CLL patients in an attempt to obtain a long-lasting eradication and possibly cure of the disease. Here we discuss the standardized and innovative technical approaches for MRD detection in CLL, the clinical impact of MRD monitoring in chemoimmunotherapy and chemo-free trials and the future clinical implications of MRD monitoring in CLL patients outside of clinical trials.

Predicting the outcome of patients with chronic lymphocytic leukemia: Progress and uncertainty

Because chronic lymphocytic leukemia is a heterogeneous disease, there are considerable efforts underway to develop increasingly accurate and precise analytics with which to estimate the probability of future events such as the need for and probability of response to therapy, progression-free survival, and survival. These analytics typically are constructed from clinical and laboratory variables. These variables often are combined into scores or staging systems, some of which are prognostic (therapy-independent), whereas others are predictive (therapy-dependent). Predictive variables differ with different therapies. Because response to therapy is a necessary condition for the improvement of survival, predictive biomarkers are extremely important. However, despite some progress to identify new predictive biomarkers, del(17p)/TP53 mutation remains the only widely accepted variable used to guide therapy. New laboratory techniques and analytical tools may contribute to improvements in the precision and accuracy of outcome indicators. However, there are inherent limitations when applying cohort-based estimates to individuals within the cohort. The accuracy and precision of prediction also are limited by measurement error and chance. Ultimately, estimating outcomes requires a careful balance between clinical experience, imperfect prediction, and uncertainty.

Distinct immunoglobulin heavy chain variable region gene repertoire and lower frequency of del(11q) in Taiwanese patients with chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is the most common leukaemia in Western countries but very rare in Asia. Peripheral blood or bone marrow mononuclear cells obtained at initial diagnosis from 194 patients with CLL were analysed to determine the ethnic difference in genetic abnormalities. Mutated IGHV was detected in 71·2% of Taiwanese CLL and IGHV3‐23 was the most frequently used gene. Stereotyped BCR was present in 18·3% with subset 8 being the most frequent. All cases with subset 8 belonged to IGHV 4‐39 and were exclusively associated with un‐mutated IGHV and poor outcome. Mutation frequencies of SF3B1 (9·7%), NOTCH1 (8·6%), BIRC3 (1·1%), ATM (16·9%) or TP53 (8·1%), and frequencies of cytogenetic abnormalities including trisomy 12 (18·6%), del(17p) (10·4%), del(13q) (43·7%) and IGH translocation (10·1%) were comparable to those reported from Western countries, except del(11q) (6·9%) which was lower in our patients. Patients with un‐mutated IGHV, subset 8, disrupted TP53, trisomy 12, and SF3B1 mutations had a worse outcome compared to patients without these mutations. In conclusion, IGHV3‐23 usage, stereotyped subset 8 and lower frequency of del(11q) show an ethnicity‐dependent association in Taiwanese CLL patients.

Prognostic Factors in the Era of Targeted Therapies in CLL

PURPOSE OF REVIEW

Chronic lymphocytic leukemia is heterogeneous disease characterized by a variable clinical course that is greatly influenced by various patient and disease characteristics. Over the last two decades, advent of new diagnostic methodologies has led to the identification of several factors of prognostic and predictive relevance. Furthermore, recent advances in next-generation sequencing techniques has identified recurrent novel mutations in NOTCH1, SF3B1, BIRC3, and ATM genes whose role as prognostic and predictive markers is currently being investigated. These biologic markers carry new prognostic information and their incorporation into prognostic scoring systems will likely lead to refined multi-parameter risk models.

RECENT FINDINGS

While the prognostic impact of many of the most commonly used markers on clinical outcomes in patients treated with chemo-immunotherapy is well documented, it is important to review their predictive and prognostic role in the era of novel targeted therapies. This article will discuss the currently available information on the clinical relevance of prognostic markers in patients treated with novel targeted therapies.

TLR2 Expression on Leukemic B Cells from Patients with Chronic Lymphocytic Leukemia

Antigenic stimulation is considered as a possible trigger of neoplastic transformation in chronic lymphocytic leukemia (CLL). B-cell receptor plays a key role in the interactions between the microenvironment and leukemic cells; however, an important role has also been attributed to Toll-like receptors (TLRs). It is believed that disorders of TLR expression may play a part in the pathogenesis of CLL. In this study, we investigated the potential role of TLR2 in CLL by analyzing its expression on leukemic B cells in correlation with clinical and laboratory parameters characterizing disease activity and patients’ immune status. We assessed the frequencies of TLR2⁺/CD19⁺ cells by the flow cytometry method in peripheral blood of 119 patients with CLL. The percentage of TLR2⁺/CD19⁺ cells was significantly lower in patients with CLL as compared to the healthy volunteers. There was also a lower percentage of TLR2⁺/CD19⁺ cells in CLL patients with poor prognostic factors, such as ZAP70 and/or CD38 expression, 17p and/or 11q deletion. On the other hand, among patients with del(13q14) associated with favorable prognosis, the percentage of TLR2⁺/CD19⁺ cells was higher than among those with del(11q22) and/or del(17p13) as well as in the control group. We found an association between low percentage of CD19⁺/CD5⁺/TLR2⁺ cells and shorter time to treatment. We also demonstrated the relationship between low percentage of CD19⁺/CD5⁺ TLR2-positive and overall survival (OS) of CLL patients. CLL patients with a proportion of 1.6% TLR2-positive B CD5⁺ cells (according to the receiver operating characteristic curve analysis) or more had a longer time to treatment and longer OS than the group with a lower percentage of TLR2 positive cells. To sum up, the results of the study suggest that low TLR2 expression is associated with poor prognosis in CLL patients. The monitoring of CD19⁺/CD5⁺/TLR2⁺ cells number may provide useful information on disease activity. Level of TLR2 expression on leukemic B cells may be an important factor of immunological dysfunction for patients with CLL. Our study suggests that TLR2 could becomes potential biological markers for the clinical outcome in patients with CLL.

Elevated absolute NK cell counts in peripheral blood predict good prognosis in chronic lymphocytic leukemia

PURPOSE

The aim of this study was to investigate the prognostic significance of the absolute natural killer (NK) cell counts in peripheral blood in patients with chronic lymphocytic leukemia (CLL).

METHODS

A total of 273 previously untreated patients with CLL from April 2004 and October 2015 were enrolled into this retrospective study. We analysed the T cell subsets of all patients and figured out the number of NK cells. Comparisons of NK cell count as continuous parameter in different groups were described using Mann-Whitney U test and the Kruskal-Wallis test. Kaplan-Meier method was used to survival analysis, and the Cox proportional hazards models were used for the estimation of prognostic factors.

RESULTS

NK cell counts were calculated in 273 therapy-naive CLL patients, and higher number of NK cell was observed in those with Binet stage A/B, ZAP-70 < 20%, normal serum albumin and β₂-microglobulin levels. Using a NK cell count cut-off of 0.40 × 10⁹/L, patients with lower NK cell count (< 0.40 × 10⁹/L) had a significantly shorter overall survival (OS) than those with higher NK cell count (≥ 0.40 × 10⁹/L) (P = 0.0014). Multivariate analysis showed that NK cell counts remained its prognostic value. However, the effect of NK cell count on time to treatment was not significant.

CONCLUSIONS

Our results suggest that NK cell count is an independent prognostic marker for OS in patients with CLL and NK cell counts ≥ 0.40 × 10⁹/L can routinely be used to identify patients with favorable survival.

Clinical utility of recently identified diagnostic, prognostic, and predictive molecular biomarkers in mature B-cell neoplasms

Genomic profiling studies have provided new insights into the pathogenesis of mature B-cell neoplasms and have identified markers with prognostic impact. Recurrent mutations in tumor-suppressor genes (TP53, BIRC3, ATM), and common signaling pathways, such as the B-cell receptor (CD79A, CD79B, CARD11, TCF3, ID3), Toll-like receptor (MYD88), NOTCH (NOTCH1/2), nuclear factor-κB, and mitogen activated kinase signaling, have been identified in B-cell neoplasms. Chronic lymphocytic leukemia/small lymphocytic lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, mantle cell lymphoma, Burkitt lymphoma, Waldenström macroglobulinemia, hairy cell leukemia, and marginal zone lymphomas of splenic, nodal, and extranodal types represent examples of B-cell neoplasms in which novel molecular biomarkers have been discovered in recent years. In addition, ongoing retrospective correlative and prospective outcome studies have resulted in an enhanced understanding of the clinical utility of novel biomarkers. This progress is reflected in the 2016 update of the World Health Organization classification of lymphoid neoplasms, which lists as many as 41 mature B-cell neoplasms (including provisional categories). Consequently, molecular genetic studies are increasingly being applied for the clinical workup of many of these neoplasms. In this review, we focus on the diagnostic, prognostic, and/or therapeutic utility of molecular biomarkers in mature B-cell neoplasms.

Differences between chronic lymphocytic leukaemia and small lymphocytic lymphoma cells by proteomic profiling and SNP microarray analysis

The majority of malignant cells in chronic lymphocytic leukaemia (CLL) circulate in the peripheral blood whereas small lymphocytic lymphoma (SLL) cells reside in tissues. The aim of this study was to detect differences in chemokine receptor expression, DNA single nucleotide polymorphism (SNP) microarray analysis and proteomic profiling to help elucidate why the cells remain in their respective environments. We identified by flow cytometric studies of chemokine receptors and DNA SNP microarray analysis significant differences between cells from CLL and SLL patients. Proteomic analysis revealed two potential markers (m/z 3091 and 8707) to distinguish the two disorders. There was a significantly greater expression of leucocyte trafficking receptor CXCR3 (CD183) and migration and homing receptor CXCR4 (CD184), and significantly lower expression of cell adhesion molecule integrin α₄ chain (CD49d), on CLL cells, compared with SLL cells. Conversely, SNP microarrays revealed greater numbers of copy-neutral loss of heterozygosity chromosomal aberrations, as well as gross chromosomal aberrations, in the SLL group, compared with the CLL group. These findings revealed that there was a significantly greater expression of trafficking, migration and homing receptors and significantly lower expression of adhesion molecules on CLL cells than on SLL cells, and that SLL may be a more progressive disease than CLL, with a more complex genotype.

Telomere shortening, TP53 mutations and deletions in chronic lymphocytic leukemia result in increased chromosomal instability and breakpoint clustering in heterochromatic regions

Complex karyotypes are associated with a poor prognosis in chronic lymphocytic leukemia (CLL). Using mFISH, iFISH, and T/C-FISH, we thoroughly characterized 59 CLL patients regarding parameters known to be involved in chromosomal instability: status of the genes ATM and TP53 and telomere length. Interestingly, a deletion of the ATM locus in 11q, independent of the cytogenetic context, was associated with significantly diminished risk (p<0.05) of carrying a mutation in TP53. In patients with loss or mutation of TP53, chromosomal breakage occurred more frequently (p<0.01) in (near-) heterochromatic regions. Median telomere length in patients with complex karyotypes was significantly shorter than that of healthy controls and shorter than in all other cytogenetic cohorts. Furthermore, the median telomere length of patients carrying a TP53 mutation was significantly shorter than without mutation. We conclude that telomere shortening in combination with loss of TP53 induces increased chromosomal instability with preferential involvement of (near-) heterochromatic regions.

Extended follow-up and impact of high-risk prognostic factors from the phase 3 RESONATE study in patients with previously treated CLL/SLL

In the phase 3 RESONATE study, ibrutinib demonstrated superior progression-free survival (PFS), overall survival (OS) and overall response rate (ORR) compared with ofatumumab in relapsed/refractory CLL patients with high-risk prognostic factors. We report updated results from RESONATE in these traditionally chemotherapy resistant high-risk genomic subgroups at a median follow-up of 19 months. Mutations were detected by Foundation One Heme Panel. Baseline mutations in the ibrutinib arm included TP53 (51%), SF3B1 (31%), NOTCH1 (28%), ATM (19%) and BIRC3 (14%). Median PFS was not reached, with 74% of patients randomized to ibrutinib alive and progression-free at 24 months. The improved efficacy of ibrutinib vs ofatumumab continues in all prognostic subgroups including del17p and del11q. No significant difference within the ibrutinib arm was observed for PFS across most genomic subtypes, although a subset carrying both TP53 mutation and del17p had reduced PFS compared with patients with neither abnormality. Reduced PFS or OS was not evident in patients with only del17p. PFS was significantly better for ibrutinib-treated patients in second-line vs later lines of therapy. The robust clinical activity of ibrutinib continues to show ongoing efficacy and acceptable safety consistent with prior reports, independent of various known high-risk mutations.

Distinct molecular genetics of chronic lymphocytic leukemia in Taiwan: clinical and pathogenetic implications

Differences in chronic lymphocytic leukemia between the Asian and the Western population are widely known. To further clarify these ethnic differences, we profiled the molecular genetics in a cohort of 83 newly diagnosed patients from Taiwan. In detail, we assessed: (i) the usage and the mutational status of the clonotypic immunoglobulin heavy-chain variable region (IgHV) genes, (ii) the presence of VH CDR3 stereotypes, and (iii) TP53, NOTCH1, SF3B1, BIRC3, and MYD88 mutations. The IgHV gene repertoire was biased and distinct from that observed in the West with the most common IgHV genes being IgHV3-23, IgHV3-7, and IgHV3-48 In terms of IgHV gene mutational status, 63.8% of patients carried mutated rearrangements, whereas 22.4% of patients were assigned to stereotyped subsets (6.9% to major subsets and 15.5% to minor ones). The frequencies of NOTCH1, SF3B1, BIRC3 and MYD88 mutations were 9.6%, 7.2%, 1.2%, and 2.4%, respectively; however, the frequency of TP53 mutations was significantly higher (20.5%). Patients with TP53 mutations or del(17p), SF3B1 mutations and unmutated IgHV had a worse outcome compared to the other patients. In conclusion, the differences observed in IgHV properties suggest different pathogenetic factors implicated in the development of chronic lymphocytic leukemia, while the high frequency of TP53 mutations could in part explain the dismal outcome of these patients in Taiwan.

IFI16 reduced expression is correlated with unfavorable outcome in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults. Its clinical course is typically indolent; however, based on a series of pathobiological, clinical, genetic, and phenotypic parameters, patient survival varies from less than 5 to more than 20 years. In this paper, we show for the first time that the expression of the interferon-inducible DNA sensor IFI16, a member of the PYHIN protein family involved in proliferation inhibition and apoptosis regulation, is associated with the clinical outcome in CLL. We studied 99 CLLs cases by immunohistochemistry and 10 CLLs cases by gene expression profiling. We found quite variable degrees of IFI16 expression among CLLs cases. Noteworthy, we observed that a reduced IFI16 expression was associated with a very poor survival, but only in cases with ZAP70/CD38 expression. Furthermore, we found that IFI16 expression was associated with a specific gene expression signature. As IFI16 can be easily detected by immunohistochemistry or flow cytometry, it may become a part of phenotypic screening in CLL patients if its prognostic role is confirmed in independent series.

Clinicopathological features and outcome of chronic lymphocytic leukaemia in Chinese patients

Chronic lymphocytic leukaemia (CLL) is uncommon in Chinese population and its biology, genetics and treatment outcome in Chinese patients have not been comprehensively investigated. In this study, we studied the clinicopathological features and outcome of 212 Chinese patients with newly diagnosed CLL in Hong Kong and Singapore. The median age at diagnosis was 64 years. The majority of patients presented with early-stage disease (Binet stage A, 56.1%). Del(13)(q14) was the most frequent abnormality (41.7%) detected by fluorescence in situ hybridization (FISH) analysis. Del(17p) and TP53 gene mutations were detected in 7.8% and 8.2% of patients, respectively. MYD88 mutations were found at a higher frequency (11.5%) than expected. CLL with unmutated variable region of the immunoglobulin heavy chain genes (IGHV) occurred in only 31.2% of cases, and was associated with advanced-stage disease (p <0.01) and adverse FISH abnormalities (p<0.01). With a median follow-up of 39 months, the median overall survival (OS) was 108 months. The presence of del(17p) or TP53 mutations was associated with a significantly shorter time to first treatment and an inferior OS (p <0.01). Unmutated IGHV was also associated with a significantly shorter time to treatment (p <0.01). Among patients who required treatment, the median OS and progression-free survival (PFS) were 107 and 23 months, respectively. The presence of del(17p) was associated with a significantly inferior OS and PFS (p <0.01). In summary, Chinese CLL patients had similar genetic aberrations at diagnosis compared with those of Western populations. FISH abnormalities are major factors affecting outcome.

Serum LDH level may predict outcome of chronic lymphocytic leukemia patients with a 17p deletion: a retrospective analysis of prognostic factors in China

Objective

This study aims to evaluate the natural history of patients with chronic lymphocytic leukemia (CLL) and a 17p deletion (17p-) and identify the predictive factors within this subgroup.

Methods

The sample of patients with CLL were analyzed by fluorescencein situ hybridization for deletions in chromosome bands 11q22, 13q14 and 17p13; trisomy of bands 12q13; and translocation involving band 14q32. The data from 456 patients with or without a 17p- were retrospectively collected and analyzed.

Results

The overall response rate (ORR) in patients with a 17p- was 56.9%, and patients with a high percentage of 17p- (defined as more than 25% of cells harbouring a 17p-) had a lower ORR. The median overall survival (OS) in patients with a 17p- was 78.0 months, which was significantly shorter than the OS in patients without this genetic abnormality (median 162.0 months, P<0.001). Within the subgroup with a 17p-, the progression-free survival was significantly shorter in patients at Binet stage B-C and patients with elevated lactate dehydrogenase (LDH), B symptoms, unmutatedIGHV and a high percentage of 17p-.

Conclusions

These results indicated that patients with a 17p- CLL have a variable prognosis that might be predicted using simple clinical and laboratory characteristics.

Chronic lymphocytic leukemia and small lymphocytic lymphoma: two faces of the same disease

INTRODUCTION

Chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL) are considered indolent lymphocytic malignancies, more often requiring active surveillance rather than intervention. Despite the indolent nature of CLL/SLL, treatment is likely indicated in a patients' lifetime. Recent changes in the therapeutic landscape have created more options to the clinician. Areas covered: The authors provide a broad assessment of the current state of disease, including the work-up, prognostic features, and mutational aspects of the disease that should be acknowledged when developing a rational treatment plan. Key studies, guideline recommendations, and expert analysis are used to create this update on CLL/SLL. Expert commentary: The recent pace of treatment additions in CLL/SLL is a welcome addition. Moving forward, it is anticipated that treatment modalities will continue to evolve, leading to additional management options that truly would define CLL/SLL as a chronic disease.

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

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

ESMO consensus conference on malignant lymphoma: general perspectives and recommendations for prognostic tools in mature B-cell lymphomas and chronic lymphocytic leukaemia

The European Society for Medical Oncology (ESMO) consensus conference on mature B-cell lymphomas and chronic lymphocytic leukaemia (CLL) was held on 20 June 2015 in Lugano, Switzerland, and included a multidisciplinary panel of 25 leading experts. The aim of the conference was to develop recommendations on critical subjects difficult to consider in detail in the ESMO Clinical Practice Guidelines. The following areas were identified: (i) the elderly patient, (ii) prognostic factors suitable for clinical use and (iii) the 'ultra-high-risk' group. Before the conference, the expert panel was divided into three working groups; each group focused on one of these areas in order to address four clinically relevant questions relating to that topic. All relevant scientific literature, as identified by the experts, was reviewed in advance. During the consensus conference, each working group developed recommendations to address each of the four questions assigned to their group. These recommendations were then presented to the entire panel and a consensus was reached. This manuscript presents recommendations dedicated to the second area of interest, i.e. prognostic factors suitable for clinical use. The four topics [i.e. interim positron emission tomography (PET), TP53 mutations, cell of origin (COO) and minimal residual disease (MRD)] were primarily chosen because of the bulk of available data together with the lack of clear guidance regarding their use in clinical practice and within clinical trials. Results, including a summary of evidence supporting each recommendation, are detailed in this manuscript. The panel acknowledged that detection of TP53 inactivation by deletion or mutation in CLL should be implemented in clinical practice (level of evidence I, strength of recommendation A). Due to their potentially high prognostic value, at least in some lymphoma entities, implementation of interim PET, COO and MRD was highly recommended in the context of clinical trials. All expert panel members approved this final article.

NF-κB activation in chronic lymphocytic leukemia: A point of convergence of external triggers and intrinsic lesions

The nuclear factor-κB (NF-κB) pathway is constitutively activated in chronic lymphocytic leukemia (CLL) patients, and hence plays a major role in disease development and evolution. In contrast to many other mature B-cell lymphomas, only a few recurrently mutated genes involved in canonical or non-canonical NF-κB activation have been identified in CLL (i.e. BIRC3, MYD88 and NFKBIE mutations) and often at a low frequency. On the other hand, CLL B cells seem 'addicted' to the tumor microenvironment for their survival and proliferation, which is primarily mediated by interaction through a number of cell surface receptors, e.g. the B-cell receptor (BcR), Toll-like receptors and CD40, that in turn activate downstream NF-κB. The importance of cell-extrinsic triggering for CLL pathophysiology was recently also highlighted by the clinical efficacy of novel drugs targeting microenvironmental interactions through the inhibition of BcR signaling. In other words, CLL can be considered a prototype disease for studying the intricate interplay between external triggers and intrinsic aberrations and their combined impact on disease evolution. In this review, we will discuss the current understanding of mechanisms underlying NF-κB deregulation in CLL, including micro-environmental, genetic and epigenetic events, and summarize data generated in murine models resembling human CLL. Finally, we will also discuss different strategies undertaken to intervene with the NF-κB pathway and its upstream mediators.

Ibrutinib downregulates a subset of miRNA leading to upregulation of tumor suppressors and inhibition of cell proliferation in chronic lymphocytic leukemia

The lymph node (LN) is the site of chronic lymphocytic leukemia (CLL) cell activation and proliferation. Aberrant microRNA (miRNA) expression has been shown to have a role in CLL pathogenesis; however, a comparison of miRNA expression between CLL cells in the LN and the peripheral blood (PB) has previously not been reported. On the basis of the analysis of 17 paired LN and PB samples from CLL patients, we identify a panel of miRNAs that are increased in LN CLL cells correlating with an activation phenotype. When evaluated in CLL cells from 38 patients pre and post treatment with ibrutinib, a subset of these miRNAs (miR-22, miR-34a, miR-146b and miR-181b) was significantly decreased in response to ibrutinib. A concomitant increase in putative miRNA target transcripts (ARID1B, ARID2, ATM, CYLD, FOXP1, HDAC1, IBTK, PTEN and SMAD4) was also observed. Functional studies confirmed targets of ibrutinib-responsive miRNAs to include messenger RNA transcripts of multiple tumor suppressors. Knockdown of endogenous miR-34a and miR146b resulted in increased transcription of tumor suppressors and inhibition of cell proliferation. These findings demonstrate that ibrutinib downregulates the expression of a subset of miRNAs related to B-cell activation leading to increased expression of miRNA targets including tumor suppressors and a reduction in cell proliferation.

Interphase Molecular Cytogenetic Detection Rates of Chronic Lymphocytic Leukemia-Specific Aberrations Are Higher in Cultivated Cells Than in Blood or Bone Marrow Smears

Banding cytogenetics is still the gold standard in many fields of leukemia diagnostics. However, in chronic lymphocytic leukemia (CLL), GTG-banding results are hampered by a low mitotic rate of the corresponding malignant lymphatic cells. Thus, interphase fluorescence in situ hybridization (iFISH) for the detection of specific cytogenetic aberrations is done nowadays as a supplement to or even instead of banding cytogenetics in many diagnostic laboratories. These iFISH studies can be performed on native blood or bone marrow smears or in nuclei after cultivation and stimulation by a suitable mitogen. As there are only few comparative studies with partially conflicting results for the detection rates of aberrations in cultivated and native cells, this question was studied in 38 CLL cases with known aberrations in 11q22.2, 11q22.3, 12, 13q14.3, 14q32.33, 17p13.1, or 18q21.32. The obtained results implicate that iFISH directly applied on smears is in general less efficient for the detection of CLL-specific genetic abnormalities than for cultivated cells. This also shows that applied cell culture conditions are well suited for malignant CLL cells. Thus, to detect malignant aberrant cells in CLL, cell cultivation and cytogenetic workup should be performed and the obtained material should be subjected to banding cytogenetics and iFISH.

Dielectrophoretic recovery of DNA from plasma for the identification of chronic lymphocytic leukemia point mutations

Aim

Circulating cell free (ccf) DNA contains information about mutations affecting chronic lymphocytic leukemia (CLL). The complexity of isolating DNA from plasma inhibits the development of point-of-care diagnostics. Here, we introduce an electrokinetic method that enables rapid recovery of DNA from plasma.

Materials & methods

ccf-DNA was isolated from 25 µl of CLL plasma using dielectrophoresis. The DNA was used for PCR amplification, sequencing and analysis.

Results

The ccf-DNA collected from plasma of 5 CLL patients revealed identical mutations to those previously identified by extracting DNA from CLL cells from the same patients.

Conclusion

Rapid dielectrophoresis isolation of ccf-DNA directly from plasma provides sufficient amounts of DNA to use for identification of point mutations in genes associated with CLL progression.

A Canadian perspective on the use of immunoglobulin therapy to reduce infectious complications in chronic lymphocytic leukemia

Infections are a major cause of morbidity and mortality in patients with chronic lymphocytic leukemia (cll), who typically have increased susceptibility because of hypogammaglobulinemia (hgg) related to their disease and its treatment. Immunoglobulin replacement therapy (igrt) has been shown to reduce the frequency of bacterial infections and associated hospitalizations in patients with hgg or a history of infection, or both. However, use of igrt in cll is contentious. Studies examining such treatment were conducted largely before the use of newer chemoimmunotherapies, which can extend lifespan, but do not correct the hgg inherent to the disease. Thus, the utility of igrt has to be re-evaluated in the current setting. Here, we discuss the evidence for the use of igrt in cll and provide a practical approach to its use in the prevention and management of infections.

Residual expression of SMYD2 and SMYD3 is associated with the acquisition of complex karyotype in chronic lymphocytic leukemia

SET and MYND domain containing 2 (SMYD2) and the SET and MYND domain containing 3 (SMYD3) are the most studied and well-characterized members of SMYD family. It has been demonstrated that their altered expression is associated with the progression of several solid tumors. Nevertheless, whether these methyltransferases exert any impact in chronic lymphocytic leukemia (CLL) remains unknown. Here, we investigated the gene expression profile of SMYD2 and SMYD3 in 59 samples of CLL and 10 normal B cells. The obtained results were associated with white blood cells (WBC) and platelet counts, ZAP-70 protein expression, and cytogenetic analysis. We found that SMYD2 and SMYD3 are overexpressed in CLL patients and, interestingly, patients with residual expression of both genes presented a high WBC count and complex karyotype. Furthermore, a strong correlation between SMYD2 and SMYD3 gene expression was unveiled. Our data demonstrate the association of a residual expression of SMYD2 and SMYD3 with CLL progression indicators and suggests both genes are regulated by a common transcriptional control in this type of cancer. These results may provide the basis for the development of new therapeutic strategies to prevent CLL progression.

Frequencies of SF3B1, NOTCH1, MYD88, BIRC3 and IGHV mutations and TP53 disruptions in Chinese with chronic lymphocytic leukemia: disparities with Europeans

We studied 307 consecutive Chinese with chronic lymphocytic leukemia (CLL) in diverse disease-stages before and after diverse therapies for mutations in several CLL-related genes. Mutation frequencies were SF3B1, 5%, NOTCH1, 8%, MYD88, 8%, BIRC3, 2%, TP53, 15% and IGHV, 60%. Several of these frequencies differ from those reported in persons of predominately European descent with CLL. Biological and clinical associations were detected including SF3B1 and NOTCH1 mutations with un-mutated IGHV, MYD88 mutations with mutated IGHV, SF3B1 mutations with fludarabine-resistant CLL and NOTCH1 mutation with advanced Binet disease stage and with +12. The NOTCH1 correlation with briefer survival was confirmed in multivariate analyses but the SF3B1 correlation was confounded by concurrent mutations in TP53 and germline IGHV. We show differences in incidence and prognostic impact of mutations in Chinese and CLL compared with persons of predominately European descent with CLL. These data may give insights into the etiology and biology of CLL and suggests different risk stratification models may be needed for different CLL populations.

Inter- and intra-patient clonal and subclonal heterogeneity of chronic lymphocytic leukaemia: evidences from circulating and lymph nodal compartments

Whole exome sequencing and copy number aberration (CNA) analysis were performed on cells taken from peripheral blood (PB) and lymph nodes (LN) of patients with chronic lymphocytic leukaemia (CLL). Of 64 non-silent somatic mutations, 54 (84·4%) were clonal in both compartments, 3 (4·7%) were PB-specific and 7 (10·9%) were LN-specific. Most of the LN- or PB-specific mutations were subclonal in the other corresponding compartment (variant frequency 0·5-5·3%). Of 41 CNAs, 27 (65·8%) were shared by both compartments and 7 (17·1%) were LN- or PB-specific. Overall, 6 of 9 cases (66·7%) showed genomic differences between the compartments. At subsequent relapse, Case 10, with 6 LN-specific lesions, and Case 100, with 6 LN-specific and 8 PB-specific lesions, showed, in the PB, the clonal expansion of LN-derived lesions with an adverse impact: SF3B1 mutation, BIRC3 deletion, del8(p23·3-p11·1), del9(p24·3-p13·1) and gain 2(p25·3-p14). CLL shows an intra-patient clonal heterogeneity according to the disease compartment, with both LN and PB-specific mutations/CNAs. The LN microenvironment might contribute to the clonal selection of unfavourable lesions, as LN-derived mutations/CNAs can appear in the PB at relapse.

Low-dose alemtuzumab in refractory/relapsed chronic lymphocytic leukemia: Genetic profile and long-term outcome from a single center experience

Relapsed/refractory chronic lymphocytic leukemia (CLL) represents a clinical challenge, in particular when high risk gene mutations occur. In this setting, alemtuzumab was recognized to be effective. This retrospective study evaluates long-term efficacy and tolerability of low-dose alemtuzumab in relapsed/refractory CLL and correlates clinical outcome with biological feature. Sixty-two consecutive patients (median age 68 years) were evaluated; alemtuzumab was administered 30 mg weekly for up to 18 weeks. Among the patients included in the analysis, 37% were fludarabine-refractory, 33.3% carried a TP53 disruption, 14.8% a NOTCH1 mutation and 9% a SF3B1 mutation. Overall response rate (ORR) was 61.3% (complete remission 25.8%). After a median follow-up of 43 months, overall survival (OS) and progression free survival (PFS) were 43.1 and 15 months, respectively; while ORR was 77.8% for patients carrying TP53 disruptions (OS 33.8 months) and 43.5% for fludarabine-refractory patients (OS 30 months). Noteworthy, long-term survivors (OS ≥ 36 months) were 54.8%. None of the biological poor risk factors negatively impacted on ORR, PFS and OS. Grade ≥3 cytopenia occurred in 24.2% patients, 6.5% experienced a grade ≥3 non-CMV infection and no grade ≥3 CMV-event occurred. In conclusion, low dose-alemtuzumab is safe and effective in relapsed/refractory CLL, also in a long-term follow-up and high-risk genetic subgroups.

Integration of microarray analysis into the clinical diagnosis of hematological malignancies: How much can we improve cytogenetic testing?

Purpose

To evaluate the clinical utility, diagnostic yield and rationale of integrating microarray analysis in the clinical diagnosis of hematological malignancies in comparison with classical chromosome karyotyping/fluorescence in situ hybridization (FISH).

Methods

G-banded chromosome analysis, FISH and microarray studies using customized CGH and CGH+SNP designs were performed on 27 samples from patients with hematological malignancies. A comprehensive comparison of the results obtained by three methods was conducted to evaluate benefits and limitations of these techniques for clinical diagnosis.

Results

Overall, 89.7% of chromosomal abnormalities identified by karyotyping/FISH studies were also detectable by microarray. Among 183 acquired copy number alterations (CNAs) identified by microarray, 94 were additional findings revealed in 14 cases (52%), and at least 30% of CNAs were in genomic regions of diagnostic/prognostic significance. Approximately 30% of novel alterations detected by microarray were >20 Mb in size. Balanced abnormalities were not detected by microarray; however, of the 19 apparently “balanced” rearrangements, 55% (6/11) of recurrent and 13% (1/8) of non-recurrent translocations had alterations at the breakpoints discovered by microarray.

Conclusion

Microarray technology enables accurate, cost-effective and time-efficient whole-genome analysis at a resolution significantly higher than that of conventional karyotyping and FISH. Array-CGH showed advantage in identification of cryptic imbalances and detection of clonal aberrations in population of non-dividing cancer cells and samples with poor chromosome morphology. The integration of microarray analysis into the cytogenetic diagnosis of hematologic malignancies has the potential to improve patient management by providing clinicians with additional disease specific and potentially clinically actionable genomic alterations.

A canadian perspective on the first-line treatment of chronic lymphocytic leukemia

Despite important advances in the treatment of first-line chronic lymphocytic leukemia (CLL) over the past decade, CLL remains an incurable disease with significant unmet needs. The combination of rituximab with fludarabine and cyclophosphamide (FCR) significantly improved overall survival and progression-free survival compared with fludarabine and cyclophosphamide alone in first-line treatment of CLL. However, because of its high toxicity, FCR is only recommended for younger, fit patients who can tolerate the treatment. This excludes a large fraction of CLL patients who are elderly and/or who have comorbidities. Thus, determining the appropriate treatment choices for this group of patients who are unfit for FCR treatment is a significant challenge in CLL. Current treatment choices in Canadian practice include bendamustine with rituximab, fludarabine with rituximab, and chlorambucil with rituximab. Two novel monoclonal antibodies, ofatumumab and obinutuzumab, have also recently received Health Canada approval for the first-line treatment of CLL patients in combination with chlorambucil. In addition, the Bruton tyrosine kinase inhibitor, ibrutinib, has recently been approved by Health Canada for the first-line treatment of CLL patients with deletion 17p. In the coming years, several other novel agents that are being developed are likely to change the CLL treatment landscape dramatically, however, because these novel agents are currently unavailable, the purpose of this review is to recommend the best treatment approaches in Canada using currently available therapies.

Molecular basis of chronic lymphocytic leukemia diagnosis and prognosis

BACKGROUNDS

Chronic lymphocytic leukemia (CLL) is the most common type of leukemia in adults and is characterized by a clonal accumulation of mature apoptosis-resistant neoplastic cells. It is also a heterogeneous disease with a variable clinical outcome. Here, we present a review of currently known (epi)genetic alterations that are related to the etiology, progression and chemo-refractoriness of CLL. Relevant literature was identified through a PubMed search (1994-2014) of English-language papers using the terms CLL, signaling pathway, cytogenetic abnormality, somatic mutation, epigenetic alteration and micro-RNA.

RESULTS

CLL is characterized by the presence of gross chromosomal abnormalities, epigenetic alterations, micro-RNA expression alterations, immunoglobulin heavy chain gene mutations and other genetic lesions. The expression of unmutated immunoglobulin heavy chain variable region (IGHV) genes, ZAP-70 and CD38 proteins, the occurrence of chromosomal abnormalities such as 17p and 11q deletions and mutations of the NOTCH1, SF3B1 and BIRC3 genes have been associated with a poor prognosis. In addition, mutations in tumor suppressor genes, such as TP53 and ATM, have been associated with refractoriness to conventional chemotherapeutic agents. Micro-RNA expression alterations and aberrant methylation patterns in genes that are specifically deregulated in CLL, including the BCL-2, TCL1 and ZAP-70 genes, have also been encountered and linked to distinct clinical parameters.

CONCLUSIONS

Specific chromosomal abnormalities and gene mutations may serve as diagnostic and prognostic indicators for disease progression and survival. The identification of these anomalies by state-of-the-art molecular (cyto)genetic techniques such as fluorescence in situ hybridization (FISH), comparative genomic hybridization (CGH), single nucleotide polymorphism (SNP) microarray-based genomic profiling and next-generation sequencing (NGS) can be of paramount help for the clinical management of these patients, including optimal treatment design. The efficacy of novel therapeutics should to be tested according to the presence of these molecular lesions in CLL patients.

Mutations in chronic lymphocytic leukemia and how they affect therapy choice: focus on NOTCH1, SF3B1, and TP53

Chronic lymphocytic leukemia (CLL) is characterized by a relatively small number of recurrent genetic defects. These can be evaluated by clinically available methods such as fluorescent in situ hybridization and targeted sequencing approaches to provide data that can be very helpful in prognostication and planning of treatment. Acquired defects in the p53 pathway, activating mutations of NOTCH1, and dysfunctional mutations of SF3B1 and BIRC3 identify patients with higher risk of progressive disease, poorer responses to conventional chemoimmunotherapy, and shorter survival. Risk stratification using these data can identify patients with aggressive CLL who require careful monitoring and are unlikely to have durable responses to chemoimmunotherapy at disease progression. Patients with defective DNA damage repair mechanisms because of p53 dysfunction should be considered for non-chemotherapy-based regimens including tyrosine kinase inhibitors, BCL2 inhibitors, monoclonal antibodies, and immunological therapies including allogeneic transplantation and chimeric antigen receptor-targeted T cells. Conversely, patients with no high-risk mutations can usually be monitored for a prolonged time and are likely to have durable responses to chemoimmunotherapy at disease progression. New technologies for genetic analysis such as targeted next-generation sequencing have the potential to make these analyses cheaper, faster, and more widely available. Comprehensive genetic analysis of patients both at diagnosis and before treatment for progressive disease could become an integral component of care for CLL.

De novo deletion 17p13.1 as a predictor for disease progression in chronic lymphocytic leukemia

To determine the prognostic impact of de novo deletion 17p13.1 (17p-) in previously untreated chronic lymphocytic leukemia (CLL) patients, we prospectively studied the outcome of 71 treatment-naïve CLL patients. About 18.3 % of them had 17p- detected by interphase fluorescent in situ hybridization (FISH) at diagnosis. There was statistically significant difference between 17p- negative and positive patients as regards 2-year overall survival [OS] (89.7 vs. 53.8 %, respectively; P = 0.001). On the other hand, 2-year progression-free survival [PFS] was also significantly higher in 17p- negative group than in 17p- positive one (82.8 vs. 23.1 %, respectively; P < 0.001). On univariate analysis for OS, 17p- positivity was significantly associated with shorter OS (P = 0.003). However, when we performed multivariate analysis, 17p- lost its significant impact. On the other hand, 17p- positivity was a significant risk factor for PFS in both univariate and multivariate analyses [independent risk factor] (P < 0.001 and P = 0.02, respectively). So, 17p- is a predictor for disease progression, but not for survival in CLL patients.

New insights into monoclonal B-cell lymphocytosis

Monoclonal B-cell lymphocytosis (MBL) is a premalignant condition characterized by the presence of less than 5000/μL circulating clonal B cells in otherwise healthy individuals. Three subcategories have been identified according to the immunophenotypic features: CLL-like, CD5(+) atypical, and CD5(−) MBL. CLL-like MBL is by far the most frequent and best studied category and further divided in low-count [LC] and high-count [HC] MBL, based on a cutoff value of 500/μL clonal B cells. LC-MBL typically remains stable and probably does not represent a truly premalignant condition, but rather an age-related immune senescence. On the other hand, HC-MBL is closely related to CLL-Rai0, bearing similar immunogenetic profile, and is associated with an annual risk of progression to CLL requiring therapy at a rate of 1.1%. Currently there are no reproducible factors for evaluating the risk of progression to CLL. CD5(−) MBL is characterized by an immunophenotype consistent with marginal zone origin and displays many similarities with marginal zone lymphomas (MZL), mainly the splenic MZL. The cutoff value of 5000/μL clonal B cells cannot probably be applied in CD5(−) MBL, requiring a new definition to describe those cases.