State of the art treatment of chronic lymphocytic leukaemia

The management of chronic lymphocytic leukaemia is currently undergoing profound changes. Several drugs like bendamustine, alemtuzumab and rituximab have recently been approved for CLL treatment by regulatory agencies. New and very promising compounds like lenalidomide, ofatumumab, GA101, flavopiridol, or ABT-263 are currently investigated in clinical trials and are likely to further enlarge the therapeutic armamentarium in the next years. Latest results show that chemoimmunotherapies like FCR (fludarabine, cyclophosphamide and rituximab) may improve the life expectancy of CLL patients. This new paradigm will modify the way of CLL management in a radical manner. Finally, the development of new biological markers that describe distinct forms of CLL allows to enter the era of personalized therapy similar to other malignancies.     

KRN5500: a novel therapeutic agent with in vitro activity against human B-cell chronic lymphocytic leukemia cells mediates cytotoxicity via the intrinsic pathway of apoptosis

Therapy of B-cell chronic lymphocytic leukemia (CLL) is currently palliative, emphasizing the need for identification of new therapies for this disease. KRN5500 is a novel agent that has a unique sensitivity pattern in the National Cancer Institute cell line screening panel, suggesting a unique mechanism of action. To assess its in vitro activity in CLL, we exposed peripheral mononuclear cells from CLL patients (n = 11) to varying concentrations of this agent. Viability of the CLL cells was reduced by 50% (LC50) at 4 hours, 24 hours, and 4 days at KRN5500 concentrations of 2.50 microM, 0.276 microM, and 0.139 microM, respectively. KRN5500 induced cellular injury via caspase-dependent apoptosis involving the intrinsic mitochondrial (caspase-9) initiating caspase and caspase-3 effector caspase; however, expression of the antiapoptotic mitochondrial membrane protein Bcl-2 was unaffected. These data demonstrate KRN5500 has significant in vitro activity against human CLL cells, thus providing support for introduction of this agent into clinical trials for patients with CLL.     

Optimal management of older patients with chronic lymphocytic leukemia: some facts and principles guiding therapeutic choices

Chronic lymphocytic leukemia (CLL) is a disease of older patients and median age at diagnosis is 72 years. This older group is under-represented in clinical trials, (median age 58-62 years). Here we review background data on incidence, survival, definitions of older age, fitness criteria, frailty and co-morbidities. Issues influencing the choice of therapy in older patients are also addressed and different therapeutic options are highlighted based on recent available data. Fit older patients with less co-morbidities benefit most from the very effective chemoimmunotherapy (FC-R) given for younger patients today, but whether other novel drug combinations or new agents are more suitable for less fit patients is still unsettled. Based on careful evaluation of published data from larger clinical trials and major referral centers we present our concept of therapy as a guide to optimal management for subgroups of older patients with CLL.     

Guidelines for clinical protocols for chronic lymphocytic leukemia: recommendations of the National Cancer Institute-sponsored working group

The National Cancer Institute (NCI)-sponsored Chronic Lymphocytic Leukemia (CLL) Working Group was convened to develop a set of standardized eligibility, response, and toxicity criteria for clinical trials. We recognized the previous efforts in 1967 (published again in 1973 as the report of the Chronic Leukemia-Myeloma Task Force [1] and 1978 of Cancer and Leukemia Group B (CALGB) [2]). We have used these reports for guidance during the current effort. Several noteworthy developments in the past few years have made it necessary to modify the previous guidelines. First, the diagnostic criteria for CLL and its clinical staging have been developed and well defined. Second, although staging systems facilitated entry of comparable and relatively homogeneous groups of patients in clinical trials, the definitions of response (CR) and partial response (PR) were not uniformly adopted from the previous guidelines in the clinical trials (Tables IA, IB); therefore, comparisons of results obtained in different studies became difficult. Third, there has been an improvement in our understanding of the immunology and biology of CLL. Finally, we are witnessing the emergence of several chemotherapy agents that promise impressive activity in CLL (e.g., 2'-deoxycoformycin [3], fludarabine monophosphate [4, 5]), and thereby offer the potential for improving survival time in this disease. To best identify regimens worthy of continued pursuit in large comparative trials, standardized guidelines for evaluation are essential. A number of laboratory investigations are also presented for which scientific interest is high yet relevance remains to be determined; thus, they are presented as companion studies to the clinical trials. This mechanism allows for flexibility in the testing of these questions and for additional ideas in the future without requiring modification of an entire treatment protocol. The following guidelines were developed to be used as a form of standardization for clinical trials, incorporating current technologies, yet remaining relevant to the general hematology/oncology community. Based on the membership of the Working Group, it is expected that these guidelines will serve as the criteria for most clinical trials in the near future.     

Treatment of chronic lymphocytic leukemia

The therapeutic landscape of chronic lymphocytic leukemia (CLL) is changing rapidly. Advances in the understanding of the biology of the CLL cell and development of new and effective therapies for CLL are starting to shift the treatment paradigm from palliation towards therapy with curative intent. Traditional chemotherapy with alkylators and/or nucleoside analogs achieves complete remissions in up to 30% to 40% of patients. Combinations of monoclonal antibodies with chemotherapy agents (chemo-immunotherapy) have almost doubled clinical complete remissions to 60% to 70%. In addition, eradication of residual disease and achievement of molecular responses have now become possible. New therapeutic agents in development and modifications of stem cell transplant are being evaluated in clinical trials. It is hoped that the combined effort of molecular biology and new therapies will lead to risk-adapted strategies and cure for some patients with CLL.     

Limited clinical relevance of imaging techniques in the follow-up of patients with advanced chronic lymphocytic leukemia: results of a meta-analysis

The clinical value of imaging is well established for the follow-up of many lymphoid malignancies but not for chronic lymphocytic leukemia (CLL). A meta-analysis was performed with the dataset of 3 German CLL Study Group phase 3 trials (CLL4, CLL5, and CLL8) that included 1372 patients receiving first-line therapy for CLL. Response as well as progression during follow-up was reassessed according to the National Cancer Institute Working Group1996 criteria. A total of 481 events were counted as progressive disease during treatment or follow-up. Of these, 372 progressions (77%) were detected by clinical symptoms or blood counts. Computed tomography (CT) scans or ultrasound were relevant in 44 and 29 cases (9% and 6%), respectively. The decision for relapse treatment was determined by CT scan or ultrasound results in only 2 of 176 patients (1%). CT scan results had an impact on the prognosis of patients in complete remission only after the administration of conventional chemotherapy but not after chemoimmunotherapy. In conclusion, physical examination and blood count remain the methods of choice for staging and clinical follow-up of patients with CLL as recommended by the International Workshop on Chronic Lymphocytic Leukemia 2008 guidelines. These trials are registered at http://www.isrctn.org as ISRCTN 75653261 and ISRCTN 36294212 and at http://www.clinicaltrials.gov as NCT00281918.     

Risk categories and refractory CLL in the era of chemoimmunotherapy

Standardized criteria for diagnosis and response evaluation in chronic lymphocytic leukemia (CLL) are essential to achieve comparability of results and improvement of clinical care. With the increasing range of therapeutic options, the treatment context is important when defining refractory CLL. Refractory CLL has been defined as no response or response lasting ≤ 6 months from last therapy. This subgroup has a very poor outcome, and many trials use this group as an entry point for early drug development. With the intensification of first-line regimens, the proportion of patients with refractory CLL using these criteria decreases. This has immediate consequences for recruitment of patients into trials as well as salvage strategies. Conversely, patients who are not refractory according to the traditional definition but who have suboptimal or short response to intense therapy also have a very poor outcome. In this Perspective, we discuss recent results that may lead to a reassessment of risk categories in CLL focusing on fit patients who are eligible for all treatment options. We cover aspects of the history and biologic basis for refractory CLL and will focus on how emerging data on treatment failure from large trials using chemoimmunotherapy may help to define risk groups in CLL.     

Current approaches to the chemotherapy of B-cell chronic lymphocytic leukemia: a review

Standard therapy has not substantially improved the outcome of patients with chronic lymphocytic leukemia (CLL). However, an increased understanding of the biology and immunology of CLL, and the availability of several new and active chemotherapy agents (eg, fludarabine, 2'-deoxycoformycin [DCF], 2-chlorodeoxyadenosine [CDA]) has stimulated enthusiasm for clinical trials. DCF induces CRs or PRs in 25% of heavily treated patients. Fludarabine has been associated with a response rate of greater than 50% in previously treated patients, and greater than 70% in untreated patients, with almost a third of these achieving a CR. Currently, phase I and II clinical trials are evaluating combinations of these drugs with each other or with conventional agents (eg, fludarabine/chlorambucil [CLB]/prednisone [P]; DCF/CLB/P; fludarabine/DCF; fludarabine/P) in previously treated patients. To facilitate comparison of these regimens, each study is adhering to the NCl-Working Group guidelines for eligibility and response criteria, and toxicity assessment. A collaborative phase III trial will then compare the most promising of these regimens with "standard" chemotherapy in previously untreated patients. The widespread availability of these clinical trials will allow clinicians ready access to the new treatments.     

Chronic lymphocytic leukaemia: current management

INTRODUCTION: Chronic lymphocytic leukemia (CLL) is the most common leukaemia in the Western world. Recent advancement in the aetiology, pathophysiology and the development of new therapeutics tools have significantly modified the current management of CLL. CURRENT KNOWLEDGE AND KEY POINTS: The cellular origin of CLL is still unknown. The current main hypothesis will be first briefly described. This review will then focus on the newly defined prognostic factors and the development and use of new drugs for the treatment of CLL. To describe the modern and practical management of CLL, we will compare classical and new prognostic markers. Then, we will discuss the various therapeutic options including chemotherapy and immunotherapy (monoclonal antibodies, allogenic transplantation), and define their current respective indications. FUTURE PROSPECTS AND PROJECTS: These new diagnostic and prognostic markers will allow the characterization of new prognostic subgroups of patients. This will lead to a targeted and individualized therapeutic approach. We will present the first results of clinical trials and the on-going studies conducted in this disease.     

Mechanisms of ibrutinib resistance in chronic lymphocytic leukaemia and non‐Hodgkin lymphoma

Bruton tyrosine kinase (BTK), a mediator of B‐cell receptor (BCR) signalling, has been implicated in the pathogenesis of chronic lymphocytic leukaemia (CLL) and other B‐cell malignancies. Ibrutinib is an orally bioavailable and highly specific BTK inhibitor that was recently approved for treatment of patients with recurrent CLL and mantle cell lymphoma (MCL). In addition, ibrutinib has shown efficacy in subsets of patients with diffuse large B cell lymphoma (DLBCL) and Waldenstrom macroglobulinaemia (WM). However, despite ibrutinib's activity in multiple B‐cell malignancies, cases of primary and secondary resistance have emerged. The overall reported frequency of resistance is low, but follow‐up in many trials was short, and we predict that the incidence of observed resistance will increase as clinical use outside clinical trials expands over time. Mutations within BTK have been described and clearly interfere with drug binding; however, there are also emerging alternative mechanisms that bypass BTK entirely and offer new opportunities for other targeted agents. Improved understanding of mechanisms of primary and secondary resistance is essential to developing appropriate therapeutic strategies to both prevent and address resistance. This review provides a comprehensive analysis of ibrutinib resistance in CLL, MCL, DLBCL and WM and considers potential strategies for further study.     

The humanized CD40 antibody SGN-40 demonstrates pre-clinical activity that is enhanced by lenalidomide in chronic lymphocytic leukaemia

Antibody-based therapies, such as rituximab and alemtuzumab, have contributed significantly to the treatment of Chronic Lymphocytic leukaemia (CLL). The CD40 antigen is expressed predominantly on B-cells and represents a potential target for immune-based therapies. SGN-40 is a humanized IgG1 monoclonal antibody currently in Phase I/II clinical trials for indolent lymphomas, diffuse large B cell lymphomas and Multiple Myeloma. Its biological effect on CLL cells has not been studied. The present study demonstrated that SGN-40 mediated modest apoptosis in a subset of patients with secondary cross-linking but did not mediate complement-dependent cytotoxicity. SGN-40 also mediated antibody-dependent cellular cytotoxicity (ADCC) predominantly through natural killer (NK) cells. Previous studies by our group and others have demonstrated that lenalidomide upregulates CD40 expression on primary B CLL cells and activates NK-cells. We therefore examined for the combinatorial effect of lenalidomide and SGN-40 and demonstrated that both enhanced direct apoptosis and ADCC against primary CLL B cells. These data together provide justification for clinical trials of SGN-40 and lenalidomide in combination for CLL therapy.     

Clinical utility of molecular and flow cytometric markers in chronic lymphocytic leukaemia

Background: Chronic lymphocytic leukaemia (CLL) is a clinically heterogeneous disease. While immunoglobulin variable region heavy chain (IgVH) mutational status remains the ‘gold standard’ in molecular prognostication, a range of additional markers is increasingly being used in clinical trials. As awareness of trial data increases, requests to determine these prognostic markers for new CLL patients are becoming more prevalent in Australia. Aim: To explore the clinical utility of currently available prognostic markers for CLL in an Australian cohort. Methods: IgVH mutational status and gene usage was determined and compared with other reported immunophenotypic markers, cytogenetics and clinical outcome as defined by treatment‐free survival (TFS), lymphocyte doubling time and clinical stage in a cohort of 65 CLL patients. Results: An unmutated IgVH gene, high expression of CD38, ZAP‐70, CD25, CD49d, CD54 or low expression of CD49c was associated with shorter TFS indicating an adverse clinical prognosis in our cohort. High expression of each of CD38, ZAP‐70, CD49d and CD54 was significantly associated with an unmutated IgVH gene; however, associations were not absolute. IgVH and CD25 expression retained their significance in multivariate analysis. Concordant CD25^high/IgVH unmutated CLL patients had the shortest median TFS interval (40 months) in our cohort. Conclusions: Molecular and immunophenotypic markers remain useful as adjuncts to clinical prognostication; however, as single parameters they are unable to dictate the timing of therapeutic intervention. The combined use of CD25 and IgVH mutational status may be clinically relevant to CLL prognostication while also providing insight into the biological pathways involved in disease progression.     

'Prolymphocytoid' Transformation of Chronic Lymphocytic Leukaemia

S ummary . We report clinical, morphological and surface marker studies on seven patients with the common type of chronic lymphocytic leukaemia (CLL) whose disease underwent an insidious though progressive change in character with increasing refractoriness to treatment. This transformation was accompanied by the appearance of a population of immature-appearing cells in the peripheral blood which resembled prolymphocytes, both at light and electron microscopy. The characteristic morphological feature was the presence of two distinct populations of cells, the typical CLL lymphocytes and the 'prolymphocytoid' cells. These cells retained the surface marker characteristics of CLL, i.e. the formation of mouse RBC rosettes and sparse surface-bound immunoglobulin. This transformation can be distinguished by morphological and surface marker criteria from acute leukaemia occurring in CLL, Richter's syndrome and prolymphocytic leukaemia. The recognition of this group of CLL patients may add a new prognostic index to CLL and may help plan subsequent trials for the treatment of the disease.     

Perspectives on the use of new diagnostic tools in the treatment of chronic lymphocytic leukemia

Recently, considerable progress has been made in the identification of molecular and cellular markers that may predict the tendency for disease progression in patients with chronic lymphocytic leukemia (CLL) or detect minimal residual disease after therapy. These developments have created uncertainty for clinicians who hope to incorporate the use of these markers and new disease-assessment tools into standard clinical practice. However, clinical trials are required to determine whether poor-prognosis leukemia-cell markers, such as expression of unmutated immunoglobulin genes or the zeta-associated protein of 70 kDa (ZAP-70), can be used as the basis for determining the time or type of therapy. Pending the outcome of such trials, treatment decisions outside the context of a clinical trial still should be based on guidelines established by the most recent National Cancer Institute-sponsored Working Group.     

Chronic lymphocytic leukemia: A prognostic model comprising only two biomarkers (IGHV mutational status and FISH cytogenetics) separates patients with different outcome and simplifies the CLL‐IPI

Rai and Binet staging systems are important to predict the outcome of patients with chronic lymphocytic leukemia (CLL) but do not reflect the biologic diversity of the disease nor predict response to therapy, which ultimately shape patients' outcome. We devised a biomarkers‐only CLL prognostic system based on the two most important prognostic parameters in CLL (i.e., IGHV mutational status and fluorescence in situ hybridization [FISH] cytogenetics), separating three different risk groups: (1) low‐risk (mutated IGHV + no adverse FISH cytogenetics [del(17p), del(11q)]); (2) intermediate‐risk (either unmutated IGHV or adverse FISH cytogenetics) and (3) high‐risk (unmutated IGHV + adverse FISH cytogenetics). In 524 unselected subjects with CLL, the 10‐year overall survival was 82% (95% CI 76%‐88%), 52% (45%‐62%), and 27% (17%‐42%) for the low‐, intermediate‐, and high‐risk groups, respectively. Patients with low‐risk comprised around 50% of the series and had a life expectancy comparable to the general population. The prognostic model was fully validated in two independent cohorts, including 417 patients representative of general CLL population and 337 patients with Binet stage A CLL. The model had a similar discriminatory value as the CLL‐IPI. Moreover, it applied to all patients with CLL independently of age, and separated patients with different risk within Rai or Binet clinical stages. The biomarkers‐only CLL prognostic system presented here simplifies the CLL‐IPI and could be useful in daily practice and to stratify patients in clinical trials.     

UCN-01 induces cytotoxicity toward human CLL cells through a p53-independent mechanism

OBJECTIVES: UCN-01, a novel protein kinase C inhibitor, is currently being tested in phase I clinical trials after being noted to induce apoptosis in lymphoid cell lines. We sought to study the in vitro activity of UCN-01 against human chronic lymphocytic leukemia (CLL) cells and potential mechanisms of action for inducing this cytotoxicity. METHODS: Detailed in vitro studies were performed from tumor cells derived from patients with CLL cells following attainment of written informed consent. RESULTS: The 50% loss of viability (LC(50)) in mononuclear cells from CLL patients (n = 10) following exposure to UCN-01 for 4 days was 0.4 microM (95% CI +/- 0.21; range 0.09-1.16). Loss of viability in human CLL cells correlated with early induction of apoptosis. Exposure of CLL cells to 0.4 and 5.0 microM of UCN-01 resulted in decreased expression of p53 protein. We therefore investigated the dependence of UCN-01 on intact p53 by exposing splenocytes from wild-type (p53(+/+)) and p53 null (p53(-/-)) mice, which demonstrated no preferential cytotoxicity when compared to the marked differential induced by F-Ara-A and radiation. CONCLUSIONS: UCN-01 has significant in vitro activity against human CLL cells that appears to occur independent of p53 status. While demonstration of in vitro cytotoxicity does not establish in vivo efficacy, the findings described support the early introduction of UCN-01 into clinical trials for patients with B-CLL.     

Aberrantly activated anti-apoptotic signalling mechanisms in chronic lymphocytic leukaemia cells: clues to the identification of novel therapeutic targets

Chronic lymphocytic leukaemia (CLL) is the commonest haematological malignancy in the western world and is incurable by cytotoxic therapy. Considerable research effort has identified the signal transduction pathways in CLL cells that contribute to anti-apoptotic signalling. Some pathways are constitutively activated in CLL cells but upregulated in normal cells only when protein tyrosine kinases (PTKs) are activated by ligands. This review describes which PTKs are aberrantly activated in CLL cells and are potential targets for inhibition. Additional potential targets within pathways downstream of these PTKs include Mek/Erk, mTorc1, protein kinase C, PI-3 kinase/Akt, nuclear factor-κB and cyclin-dependent protein kinase. Numerous studies have identified chemical agents and antibodies that selectively kill CLL cells, irrespective of their genetic resistance to conventional chemotherapeutic agents, and which can overcome cytoprotective microenvironmental signalling. These studies have resulted in identification of novel therapies, some of which are currently undergoing clinical trials. In vitro and animal model studies and clinical trials could determine which inhibitors of which targets are the likely to be most effective and least toxic either singly or in combination.     

Chlorinated adenosine analogue induces AMPK and autophagy in chronic lymphocytic leukaemia cells during therapy

8‐chloro‐adenosine (8‐Cl‐Ado) is currently in phase‐I clinical trials for acute myeloid leukaemia and chronic lymphocytic leukaemia (CLL). Previously, we demonstrated that treatment with 8‐Cl‐Ado leads to diminished ATP levels. We hypothesized that AMP‐activated protein kinase (AMPK) signalling would be initiated in these cells, leading to induction of autophagy. AMPK activation and induction of autophagy were demonstrated during preclinical incubations in CLL cells with the analogues. Importantly, we extended similar observations in CLL lymphocytes during an 8‐Cl‐Ado phase‐I trial. In conclusion, 8‐Cl‐Ado treatment induces autophagy in CLL lymphocytes in vitro as well as in vivo during clinical trial.     

Externally validated predictive clinical model for untreated del(17p13.1) chronic lymphocytic leukemia patients

Little is known about outcomes of patients with chronic lymphocytic leukemia (CLL) with del(17p13.1) karyotype at diagnosis. We reviewed 114 de novo del(17p13.1) CLL patients seen at our institution. Using proportional hazards models to identify pretreatment clinical variables significantly associated with treatment‐free survival (TFS) and overall survival (OS), we developed a simplified risk score for de novo del(17p13.1) CLL patients to predict TFS and OS based on these variables. These scores, particularly the very highest, can be utilized to identify high‐risk patients for expedient enrollment on clinical trials. Our data support careful observation for low‐risk patients, potentially preventing unnecessary use of aggressive therapies. Am. J. Hematol. 90:967–969, 2015. © 2015 Wiley Periodicals, Inc.     

New modalities of therapy in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is the most cormmon form of leukemia in adults in Western countries. After several decades of relative inactivity, important progress has been made in our understanding of the biology and immunology of this disorder. In addition, exciting therapeutic results have been achieved with several new, unique, and effective therapies. The most interesting chemotherapeutic agent is fludarabine, a purine analogue which achieves complete remission in 13% of relapsed or refractory patients and in greater than 30% of previously untreated patients; the overall response rates of 60% and 75%, respectively, are superior to reports with other single agents or combination regimens. Related drugs with promising activity are 2'-deoxycoformycin, and 2-chlorodeoxyadenosine. Preliminary studies are evaluating allogeneic and autologous bone marrow transplantation as potentially curative therapy. Biological approaches exploiting new insights into the immunology of CLL include the use of lymphoid growth factors. Interpretation of results of CLL studies has suffered from variability in eligibility and response criteria, especially definitions of complete remission. Recently published standardized guidelines for CLL clinical trials will facilitate comparisons among therapies and help identify those which are most promising. Continued progress will require integration of laboratory science and clinical investigation.