Alkylating agents and nucleoside analogues in the treatment of B cell chronic lymphocytic leukemia

Rhodamine B-Conjugated Fluorescent Block Copolymer Micelles for Efficient Chlorambucil Delivery and Intracellular Imaging

The clinical development of the anticancer drug chlorambucil (CHL) is limited by its low solubility in water, poor bioavailability, and off-target toxicity. Besides, another constraint for monitoring intracellular drug delivery is the non-fluorescent nature of CHL. Nanocarriers based on block copolymers of poly(ethylene glycol)/poly(ethylene oxide) (PEG/PEO) and poly(ε-caprolactone) (PCL) are an elegant choice for drug delivery applications due to their high biocompatibility and inherent biodegradability properties. Here, we have designed and prepared block copolymer micelles (BCM) containing CHL (BCM-CHL) from a block copolymer having fluorescent probe rhodamine B (RhB) end-groups to achieve efficient drug delivery and intracellular imaging. For this purpose, the previously reported tetraphenylethylene (TPE)-containing poly(ethylene oxide)-b-poly(ε-caprolactone) [TPE-(PEO-b-PCL)₂] triblock copolymer was conjugated with RhB by a feasible and effective post-polymerization modification method. In addition, the block copolymer was obtained by a facile and efficient synthetic strategy of one-pot block copolymerization. The amphiphilicity of the resulting block copolymer TPE-(PEO-b-PCL-RhB)₂ led to the spontaneous formation of micelles (BCM) in aqueous media and successful encapsulation of the hydrophobic anticancer drug CHL (CHL-BCM). Dynamic light scattering and transmission electron microscopy analyses of BCM and CHL-BCM revealed a favorable size (10-100 nm) for passive targeting of tumor tissues via the enhanced permeability and retention effect. The fluorescence emission spectrum (λ_ex 315 nm) of BCM demonstrated Förster resonance energy transfer between TPE aggregates (donor) and RhB (acceptor). On the other hand, CHL-BCM revealed TPE monomer emission, which may be attributed to the π-π stacking interaction between TPE and CHL molecules. The in vitro drug release profile showed that CHL-BCM exhibits drug release in a sustained manner over 48 h. A cytotoxicity study proved the biocompatibility of BCM, while CHL-BCM revealed significant toxicity to cervical (HeLa) cancer cells. The inherent fluorescence of RhB in the block copolymer offered an opportunity to directly monitor the cellular uptake of the micelles by confocal laser scanning microscopy imaging. These results demonstrate the potential of these block copolymers as drug nanocarriers and as bioimaging probes for theranostic applications.

Promoting Dual-Targeting Anticancer Effect by Regulating the Dynamic Intracellular Self-Assembly

Despite the promise of nanomedicine in the fight against complex diseases, the enthusiasm for its pharmaceutical development is backed by the elevated costs associated with the R&D process. Therefore, as a compromise solution, nanotechnology was mainly applied as a drug delivery system to improve bioavailability and controllability of pharmaceutical drugs. Attempting to break the restrictions without elevating potential costs, we multiply the functions of excipients in the nanodelivery system by endowing subcellular-targeting ability. To prove the concept, fluorescent endoplasmic reticulum-targeted short peptides were covalently connected to chemotherapy medication chlorambucil achieving enhanced drug-loading efficiency. Via visualized intracellular dynamic enzyme-catalyzed hydrolysis, the ER-targeting excipient and nucleus-targeting chlorambucil are released simultaneously, achieving a synergistic anticancer effect and elucidating the influence of intracellular self-assembly transition on enzymatic reactions.

Aromatic Nitrogen Mustard-Based Autofluorescent Amphiphilic Brush Copolymer as pH-Responsive Drug Delivery Vehicle

Delivery of clinically approved nonfluorescent drugs is facing challenges because it is difficult to monitor the intracellular drug delivery without incorporating any integrated fluorescence moiety into the drug carrier. The present investigation reports the synthesis of a pH-responsive autofluorescent polymeric nanoscaffold for the administration of nonfluorescent aromatic nitrogen mustard chlorambucil (CBL) drug into the cancer cells. Copolymerization of poly(ethylene glycol) (PEG) appended styrene and CBL conjugated N-substituted maleimide monomers enables the formation of well-defined luminescent alternating copolymer. These amphiphilic brush copolymers self-organized in aqueous medium into 25-68 nm nanoparticles, where the CBL drug is enclosed into the core of the self-assembled nanoparticles. In vitro studies revealed ∼70% drug was retained under physiological conditions at pH 7.4 and 37 °C. At endolysosomal pH 5.0, 90% of the CBL was released by the pH-induced cleavage of the aliphatic ester linkages connecting CBL to the maleimide unit. Although the nascent nanoparticle (without drug conjugation) is nontoxic, the drug conjugated nanoparticle showed higher toxicity and superior cell killing capability in cervical cancer (HeLa) cells rather than in normal cells. Interestingly, the copolymer without any conventional chromophore exhibited photoluminescence under UV light irradiation due to the presence of "through-space" π-π interaction between the C═O group of maleimide unit and the adjacent benzene ring of the styrenic monomer. This property helped us intracellular tracking of CBL conjugated autofluorescent nanocarriers through fluorescence microscope imaging. Finally, the 4-(4-nitrobenzyl)pyridine (NBP) colorimetric assay was executed to examine the ability of CBL-based polymeric nanomaterials toward alkylation of DNA.

Photocaging of Single and Dual (Similar or Different) Carboxylic and Amino Acids by Acetyl Carbazole and its Application as Dual Drug Delivery in Cancer Therapy

A new fluorescent photoremovable protecting group (FPRPG) based on acetylcarbazole framework has been explored for the first time release of single and dual (similar or different) substrates from single chromophore. Mechanistic studies of the photorelease process revealed that photorelease of two (similar or different) substrates from acetyl carbazole proceeds via a stepwise pathway. Further, we constructed photoresponsive dual drug delivery system (DDS) to release two different anticancer drugs (caffeic acid and chlorambucil, 1 equiv each). In vitro study reveals that our DDS exhibit excellent properties like biocompatibility, cellular uptake, and photoregulated dual drug release.

Management of chronic lymphocytic leukemia (CLL) in the era of B-cell receptor signal transduction inhibitors

The treatment of patients with chronic lymphocytic leukemia (CLL), an indolent B-cell lymphoma is in the midst of a transformation. There are a large number of promising new therapeutic agents and cellular therapies being studied which exhibit remarkable activity, favorable toxicity profiles, convenient administration schedules, and treatment options are rapidly expanding. The recent advances in the management of CLL exemplify the value of translational medicine. This review highlights key aspects of B-cell receptor (BCR) signaling in relation to novel inhibitors of the BCR signaling pathway, currently at various stages of preclinical and clinical development.

Trichostatin A effectively induces apoptosis in chronic lymphocytic leukemia cells via inhibition of Wnt signaling and histone deacetylation

BACKGROUND

The ontogenetic Wnt pathway shows almost no activity in adult tissues. In contrast, chronic lymphocytic leukemia (CLL) cells show constitutionally active Wnt signaling, which is associated with upregulated levels of pathway members such as Wnt3 and lymphoid enhancer-binding factor-1. Functionally, this results in increased resistance to apoptosis. We therefore assumed that targeting members of the pathway could reveal new therapeutic options for the treatment of CLL.

METHODS

Screening a Wnt compound library with 75 Wnt modulators via ATP assay revealed Trichostatin A as an outstanding substance with strong viability decreasing effects on CLL cells and little effect on healthy peripheral blood mononuclear cells (PBMCs). Further survival analysis was performed via fluorescence-activated cell sorting analysis.

RESULTS

A maximum effect was achieved after 48 h with a wide therapeutic window in contrast to PBMCs (CLL cells: 0.253 µM, PBMCs: 145.22 µM). Trichostatin A induced caspases and acted via a dual mechanism to reveal histone and non-histone targets. Histone targets were displayed in deacetylation inhibition at DNA level, and non-histone targeting was demonstrated by elevated levels of Dickkopf-related protein 1 mRNA. Primary cells of patients with critical mutations such as TP53 or those who had already undergone extensive previous treatment responded well to the treatment. Moreover, the approved histone deacetylase (HDAC) inhibitor suberoylanilidehydroxamic acid (SAHA) was not as effective as Trichostatin A (Trichostatin A: 0.253 µM, SAHA: 7.88 µM). Combining Trichostatin A with established CLL drugs fludarabine or bendamustine showed an additive effect in vitro.

CONCLUSION

Taken together, Trichostatin A appears to act via a dual anti-HDAC/Wnt mechanism with a high selectivity and efficacy in CLL and therefore warrants further investigation.

B-cell antigen receptor signaling in chronic lymphocytic leukemia: therapeutic targets and translational opportunities

B-cell chronic lymphocytic leukemia (CLL) is characterized by clonally expanded and molecularly heterogeneous populations of B lymphocytes with impaired apoptotic mechanisms. This occurs as a result of multiple genetic and epigenetic abnormalities, including chromosomal aberrations and enhancer region hypomethylation, often impinging on intracellular signaling pathways that are essential to normal B-cell activation, proliferation, and survival. The B-cell antigen receptor (BCR) signaling is one such pathway usurped by malignant B cells, as exemplified by the early phase clinical success achieved by small-molecule agents targeting key players involved in the pathway. Such new targeted agents, including those that inhibit the function of Spleen tyrosine kinase (SYK), Bruton's tyrosine kinase (BTK), phosphatidylinositol 3-kinases (PI3K), and B-cell lymphoma 2 (BCL-2), along with the current standard therapy comprising chemo-immunotherapies with or without B-cell depleting biologic agent rituximab (anti-CD20 monoclonal antibody), should expand the armamentarium for CLL therapy. We review the therapeutic agents currently in clinical development which target different effectors of the malignant BCR signaling, and discuss their overlapping and discriminating translational opportunities in the context of CLL treatment.

Second Malignancies and Richter's Syndrome in Patients with Chronic Lymphocytic Leukemia

Second malignancies are frequent complications in patients with chronic lymphocytic leukemia (CLL). Patients with this leukemia may develop large cell lymphoma (LCL) known as Richter's syndrome (RS). RS occurs in CLL patients of about 3% and may develop in a single lymph node or more often in a group of nodes. However, in some patients extranodal localization of aggressive lymphoma in RS has been observed. Besides LCL, Hodgkin's disease, prolymphocytoid leukemia, multiple myeloma and acute lymphoblastic leukemia may also occur as RS variants. The origin of lymphoid cells in RS remains tentative. However, CLL and RS originate from the same clone for some patients, whereas, in other patients cells of aggressive lymphoma do not have the features of the same clone as the CLL cells. The prognosis of RS is poor. Survival in different studies will be usually 2-5 months. The secondary development or coexistence of myeloproliferative disorders or myelodysplastic syndrome and solid tumors have also been rarely documented in CLL patients. It is of great concern that therapy may further increase the risk of a second neoplasm. However, until now, there are no clear evidence that alkylating agents or purine nucleoside analogs may be associated with an increased incidence of second malignancies in patients with CLL. In this review, epidemiology, biology, clinical characteristic and treatment approaches in RS and other secondary neoplasms in patients with CLL are discussed.

The influence of maltotriose-modified poly(propylene imine) dendrimers on the chronic lymphocytic leukemia cells in vitro: dense shell G4 PPI

Chronic lymphocytic leukemia (CLL) is the most common leukemia in Europe and North America. For many years scientists and doctors have been working on introducing the most effective therapy into CLL as prognosis of survival time and the course of the disease differ among patients, which might pose a problem in treating. Nanotechnology is providing new insights into diagnosis and, compared with conventional treatments, more efficient treatments, which might improve patients' comfort by decreasing side effects. Among the various nanoparticles that are available, dendrimers are one of the most promising. The aim of this study was a preliminary assessment of the clinical value of treating CLL patients with fourth generation poly(propylene imine) (PPI) dendrimers-either unmodified (PPI-G4) or approximately 90% maltotriose-modified (PPI-G4-DS-Mal-III). PPI-G4-DS-Mal-III dendrimers have, in contrast to the cationic PPI-G4, a neutral surface charge and are characterized by low cyto-, geno-, and hematotoxicity in vitro and in vivo. For the in vitro study we used blood mononuclear cells collected from both untreated CLL patients and from healthy donors. Apoptosis was measured by an annexin-V (Ann-V)/propidium iodide (IP) assay, and mitochondrial membrane potential was estimated with use of Mito Tracker Red CMXRos. Presented results confirm the influence of dendrimers PPI-G4 and PPI-G4-DS-Mal-III on apoptosis and CLL lymphocytes viability in in vitro cultures. Both tested dendrimers demonstrated higher cytotoxicity to CLL cells than to healthy donors cells, whereas unmodified dendrimers were more hematotoxic. The surface modification clearly makes glycodendrimers much more suitable for biomedical applications than unmodified PPI-G4; therefore further biological evaluations of these nanoparticles are conducted in our laboratories.

Emerging monoclonal antibodies and related agents for the treatment of chronic lymphocytic leukemia

Monoclonal antibodies (mAbs) – rituximab, ofatumumab and alemtuzumab – have been approved for use in the therapy of chronic lymphocytic leukemia (CLL). Recently, a new generation of anti-CD20 mAbs has become available for preclinical studies and clinical trials. These antibodies were engineered to have augmented antitumor activity by increasing complement-dependent cytotoxicity, antibody-dependent cellular cytotoxicity and Fc-binding affinity for the low-affinity variants of the Fcγ receptor IIIa. The most promising mAb directed against CD20 is obinutuzumab (GA-101). mAbs directed against CD22, CD37 and CD40 have also shown some activity in CLL. In addition, small modular immunopharmaceuticals – TRU-015 (anti-CD20) and TRU-016 (anti-CD37) – that retain Fc-mediated effector functions have been developed and investigated in preclinical studies and clinical trials. Antibody–drug conjugates and recombinant immunotoxins are also being evaluated in lymphoid malignancies. Further studies will elucidate the role of these agents in the treatment of CLL.

Standard of care and novel treatments for chronic lymphocytic leukemia

PURPOSE

The standard of care and novel treatments for chronic lymphocytic leukemia (CLL) are reviewed.

SUMMARY

Recent advances in the treatment of CLL have dramatically changed the therapeutic landscape for both patients and health care professionals. The majority of conventional first-line therapies are noncurative and are only used to treat disease that is symptomatic or progressive and include chlorambucil, monotherapy with purine analogues, and combination chemotherapy. Immunotherapeutic agents such as rituximab and alemtuzumab may be indicated in select patient populations. However, because clinical trials have found that overall survival does not depend on the initial therapy, selection of first-line therapy should be based on patient-specific factors and the patient's goals for therapy with respect to response, survival, and symptom palliation. Progression-free survival time and time to treatment are critical endpoints for CLL treatment. An increasingly important endpoint is minimal residual disease (MRD), as it is considered to be the major cause of relapse in CLL. Finally, comparison of toxicities between different therapies is critical in CLL, as it is in other disease states. Several new agents are currently being evaluated for use in CLL, including alvocidib, oblimersen, and lumiliximab.

CONCLUSION

Chemotherapy remains the mainstay of treatment for the majority of patients with CLL. The introduction of rituximab, alemtuzumab, and bendamustine has improved the current outlook for patients with CLL. As overall survival does not appear to depend on the initial therapy, treatment should be selected based on patient-specific factors and goals. Challenges in CLL include determining when to initiate therapy, eradicating MRD, and managing therapeutic resistance.

Rituximab and subcutaneous cladribine in chronic lymphocytic leukemia for newly diagnosed and relapsed patients

The aim of this study was to investigate the efficacy of combined treatment with rituximab and subcutaneous cladribine in patients with newly diagnosed and relapsed chronic lymphocytic leukemia (CLL). Forty-three patients with active CLL or small lymphocytic lymphoma received rituximab 375 mg/m(2) on day 1 and cladribine 0.1 mg/kg subcutaneously on days 2-6. The treatment was repeated every 4 weeks for a total of four cycles. Sixteen patients were pretreated. The overall response rate was 88% (50% complete remission and 38% partial remission). The median time to treatment failure was 37.9 months. Grade 4 neutropenia developed in 5% of patients. The data indicate that combination therapy with rituximab and cladribine is a valuable and safe treatment for patients with CLL.

Assessment of chemoselective neoglycosylation methods using chlorambucil as a model

To systematically assess the impact of glycosylation and the corresponding chemoselective linker upon the anticancer activity/selectivity of the drug chlorambucil, herein we report the synthesis and anticancer activities of a 63-member library of chlorambucil-based neoglycosides. A comparison of N-alkoxyamine-, N-acylhydrazine-, and N-hydroxyamine-based chemoselective glycosylation of chlorambucil revealed sugar- and linker-dependent partitioning among open- and closed-ring neoglycosides and corresponding sugar-dependent variant biological activity. Cumulatively, this study represents the first neoglycorandomization of a synthetic drug and expands our understanding of the impact of sugar structure upon product distribution/equilibria in the context of N-alkoxyamino-, N-hydroxyamino-, and N-acylhydrazine-based chemoselective glycosylation. This study also revealed several analogues with increased in vitro anticancer activity, most notably D-threoside 60 (NSC 748747), which displayed much broader tumor specificity and notably increased potency over the parent drug.

Current and emerging treatments for chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is the most common adult leukaemia in Europe and North America. The disease is characterized by proliferation and accumulation of small CD5+ B cells in blood, lymph nodes, spleen, liver and bone marrow. The natural clinical course of CLL is highly variable, and chemotherapy is usually not indicated in early and stable disease. However, patients with progressive and more advanced CLL require treatment. For many years, chlorambucil with or without corticosteroids was used in previously untreated patients with CLL. More recently, purine nucleoside analogues (PNAs) [fludarabine, cladribine and pentostatin] have been included in treatment approaches for this disease, and chlorambucil is no longer the leading standard everywhere. Currently, this drug is rather recommended for the treatment of older, unfit patients with co-morbidities, especially in European countries. Significantly higher overall response (OR) and complete response (CR) rates in patients treated initially with PNAs than in those treated with chlorambucil or cyclophosphamide-based combination regimens have been confirmed in randomized, prospective, multicentre trials. Moreover, PNAs administered in combination with cyclophosphamide produce higher response rates, including CR and molecular CR, compared with PNA as monotherapy. Recent reports suggest that the administration of monoclonal antibodies (mAbs) can significantly improve the course of CLL. At present, two mAbs have the most important clinical value in patients with CLL. The first is rituximab, a human mouse antibody that targets CD20 antigens, and the second is alemtuzumab, a humanized form of a rat antibody active against CD52. Several recent reports suggest that in patients with CLL, rituximab combined with a PNA can increase the OR and CR rates compared with PNA or rituximab alone, with acceptable toxicity. In randomized trials, the combination of rituximab with fludarabine and cyclophosphamide (FC-R regimen) demonstrated higher rates of OR, CR and progression-free survival in patients with previously untreated and relapsed or refractory CLL than fludarabine plus cyclophosphamide (FC regimen). Several reports have confirmed significant activity with alemtuzumab in relapsed or refractory CLL, as well as in previously untreated patients. Recently, several new agents have been investigated and have shown promise in treating patients with CLL. These treatments include new mAbs, agents targeting the antiapoptotic bcl-2 family of proteins and receptors involved in mediating survival signals from the microenvironment, antisense oligonucleotides and other agents. The most promising are new mAbs directed against the CD20 molecule, lumiliximab and anti-CD40 mAbs. Oblimersen, alvocidib (flavopiridol) and lenalidomide are also being evaluated both in preclinical studies and in early clinical trials. In recent years, a significant improvement in haematopoietic stem cell transplantation (HSCT) procedures in patients with high-risk CLL has been observed. However, the exact role of HSCT, autologous or allogeneic, in the standard management of CLL patients is still undefined.

Skin lesions in chronic lymphocytic leukemia

Cutaneous lesions occur in up to 25% of patients with chronic lymphocytic leukemia (CLL). These can be caused by either cutaneous seeding by leukemic cells (leukemia cutis, LC) and other malignant diseases or nonmalignant disorders. Skin infiltration with B-lymphocyte CLL manifests as solitary, grouped, or generalized papules, plaques, nodules, or large tumors. Prognosis in CLL patients with LC is rather good and many authors claim that it does not significantly affect patients' survival. However, prognosis is poor in patients in whom LC shows blastic transformation (Richter's syndrome) and when leukemic infiltrations in the skin appear after the diagnosis of CLL. Secondary cutaneous malignancies are also frequent complications in patients with CLL. A higher risk was seen in skin cancer, for which eightfold higher occurrence has been stated. There are some suggestions that alkylating agents and purine analogs may be associated with an increased incidence of secondary malignancies in CLL. Nonspecific, secondary cutaneous lesions are frequently observed in CLL patients. The most common secondary cutaneous changes seen in CLL are those of infectious or hemorrhagic origin. Other secondary lesions present as vasculitis, purpura, generalized pruritus, exfoliative erythroderma, and paraneoplastic pemphigus. An exaggerated reaction to an insect bite and insect bite-like reactions have been also observed.

Current status of older and new purine nucleoside analogues in the treatment of lymphoproliferative diseases

For the past few years more and more new cytotoxic agents active in the treatment of hematological malignancies have been synthesized and become available for either in vitro studies or clinical trials. Among them the class of antineoplastic drugs belonging to the purine nucleoside analogues group (PNAs) plays an important role. Three of them: pentostatin (DCF), cladribine (2-CdA) and fludarabine (FA) were approved by Food and Drug Administration (FDA) for the treatment of hematological malignancies. Recently three novel PNAs: clofarabine (CAFdA), nelarabine (ara-G) and forodesine (immucillin H, BCX-1777) have been synthesized and introduced into preclinical studies and clinical trials. These agents seem to be useful mainly for the treatment of human T-cell proliferative disorders and they are currently undergoing clinical trials in lymphoid malignancies. However, there are also several studies suggesting the role of these drugs in B-cell malignancies. This review will summarize current knowledge concerning the mechanism of action, pharmacologic properties, clinical activity and toxicity of PNAs accepted for use in clinical practice, as well as new agents available for clinical trials.

Growth arrest of BCR-ABL positive cells with a sequence-specific polyamide-chlorambucil conjugate

Chronic myeloid leukemia (CML) is characterized by the presence of a constitutively active Abl kinase, which is the product of a chimeric BCR-ABL gene, caused by the genetic translocation known as the Philadelphia chromosome. Imatinib, a selective inhibitor of the Bcr-Abl tyrosine kinase, has significantly improved the clinical outcome of patients with CML. However, subsets of patients lose their response to treatment through the emergence of imatinib-resistant cells, and imatinib treatment is less durable for patients with late stage CML. Although alternative Bcr-Abl tyrosine kinase inhibitors have been developed to overcome drug resistance, a cocktail therapy of different kinase inhibitors and additional chemotherapeutics may be needed for complete remission of CML in some cases. Chlorambucil has been used for treatment of B cell chronic lymphocytic leukemia, non-Hodgkin's and Hodgkin's disease. Here we report that a DNA sequence-specific pyrrole-imidazole polyamide-chlorambucil conjugate, 1R-Chl, causes growth arrest of cells harboring both unmutated BCR-ABL and three imatinib resistant strains. 1R-Chl also displays selective toxicities against activated lymphocytes and a high dose tolerance in a murine model.

Calorimetric study as a potential test for choosing treatment of B-cell chronic lymphocytic leukemia

Differential scanning calorimetry (DSC) and complementary techniques were utilized to evaluate the sensitivity of B-cell chronic lymphocytic leukemia (B-CLL) cell samples in vitro exposed to cladribine or fludarabine in combination with mafosfamide. Mafosfamide, the active in vitro form of cyclophosphamide with both purine analogs produced the cytotoxic effect on mononuclear cell probes, however, to a different degree. Our results indicated that higher sensitivity of examined leukemic cell samples to the used drug combinations was usually accompanied by a marked decrease or even a complete loss of thermal transition at 95+/-3 degrees C in DSC scans of nuclear preparations as well as by more significant reduction of cell viability, higher extent of DNA damage estimated by the comet assay and by dropping/disappearance of anti-apoptotic protein Mcl-1 in comparison with untreated cells. We have also observed that the reduction of transition at 95+/-3 degrees C in thermal scans of nuclear preparations isolated from blood of B-CLL randomized patients who showed response to cladribine or fludarabine combined with cyclophosphamide, i.e., CC and FC, respectively, corresponded with the decrease or disappearance of anti-apoptotic proteins Bcl-2 and/or Mcl 1. In conclusion, these in vitro and in vivo studies revealed that quick DSC technique, usually supplemented by other methods, is a potent tool to distinguish efficacy of B-CLL treatment and could be helpful in choosing the most effective manner of treatment for this type of leukemia.

Molecular allelokaryotyping of early-stage, untreated chronic lymphocytic leukemia

BACKGROUND

To the authors' knowledge, genetic abnormalities in early-stage chronic lymphocytic leukemia (CLL) have not been examined fully. Single nucleotide polymorphism (SNP) genomic array (SNP-chip) is a new tool that can detect copy number changes and uniparental disomy (UPD) over the entire genome with very high resolution.

METHODS

The authors performed SNP-chip analysis on 56 samples from patients with early-stage, untreated CLL. To validate the SNP-chip data, fluorescence in situ hybridization (FISH) analysis was performed at selected sites. Expression levels of ZAP-70 and the mutational status of immunoglobulin heavy-chain gene also were examined.

RESULTS

SNP-chip analysis easily detected nearly all changes that were identified by FISH, including trisomy 12, deletion of TP53 (17p13), deletion of ATM (11q22), and deletion of 13q14. Only 10 of 56 CLL samples (18%) had no genomic abnormalities. Excluding the 4 common abnormalities mentioned above, 25 CLL samples (45%) had a total of 45 copy number changes detected by SNP-chip analysis. Four samples had 6q deletion at 6q21 that involved the AIM1 gene. UPD was detected in 4 samples; 2 samples involved whole chromosome 13 resulting in homozygous deletion of micro-RNA-15a (miR-15a)/miR-16-1. CLL samples with deletion of 13q14 and trisomy 12 were mutually exclusive.

CONCLUSIONS

Genetic abnormalities, including whole chromosome 13 UPD, are very common events in early-stage CLL. SNP-chip analysis can detect small genetic abnormalities in CLL and may be able to support or even supplant FISH and cytogenetics.

Modulation of the human equilibrative nucleoside transporter1 (hENT1) activity by IL-4 and PMA in B cells from chronic lymphocytic leukemia

Nucleoside transporters (NTs) are essential for the uptake of therapeutic nucleoside analogs, broadly used in cancer treatment. The mechanisms responsible for NT regulation are largely unknown. IL-4 is a pro-survival signal for chronic lymphocytic leukemia (CLL) cells and has been shown to confer resistance to nucleoside analogs. The aim of this study was to investigate whether IL-4 is able to modulate the expression and function of the human equilibrative NT1 (hENT1) in primary cultures of CLL cells and, consequently, to affect cytotoxicity induced by therapeutic nucleosides analogs. We found that treatment with IL-4 (20 ng/ml for 24 h) increased mRNA hENT1 expression in CLL cells without affecting that of normal B cells. Given that the enhanced mRNA levels of hENT1 in CLL cells did not result in increased transport activity, we examined the possibility that hENT1 induced by IL-4 may require post-translational modifications to become active. We found that the acute stimulation of PKC in IL-4-treated CLL cells by short-term incubation with PMA significantly increased hENT1 transport activity and favoured fludarabine-induced apoptosis. By contrast, and in line with previous reports, IL-4 plus PMA protected CLL cells from a variety of cytotoxic agents. Our findings indicate that the combined treatment with IL-4 and PMA enhances hENT1 activity and specifically sensitizes CLL cells to undergo apoptosis induced by fludarabine.

Recent progress in the management of chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is a clonal disease characterized by proliferation and accumulation of small CD5-positive B cells. More than 50% of patients are asymptomatic at diagnosis and usually require no treatment. However, treatment is needed in the advanced and progressive disease. Chlorambucil with or without steroids has been the drug of choice for many years in previously untreated patients with CLL. The purine nucleoside analogs (PNAs), fludarabine (FA), cladribine (2-CdA-chlorodeoxyadenosine) and pentostatin (DCF, 2'-deoxycoformycin) also have been introduced for treatment of CLL. Significantly higher overall response (OR) and complete response (CR) and longer progression free survival (PFS) in patients with CLL treated with FA or 2-CdA have been confirmed in randomized, multicenter trials and more recently in meta-analysis. However, the median survival time did not differ between patients treated with PNA and alkylating agents. Combination therapies with PNAs and cyclophosphamide and especially with cyclophosphamide and rituximab are more active than monotherapy in terms of OR, CR and PFS. Several reports have shown significant activity of alemtuzumab in previously untreated and pretreated patients even when refractory to FA. Alemtuzumab also can be used in CLL as a preparative regimen before stem cell transplantation (SCT) and to eliminate minimal residual disease (MRD). Recently, several new agents have shown promise in treating CLL, including new monoclonal antibodies, agents targeting bcl-2 family of proteins, antisense oligonucleotides and other agents. Moreover, autologous and allogenic hematopoietic cell transplantations are increasingly considered for treatment of patients with CLL. In this review current therapeutic strategies in CLL are presented.

Primary cutaneous marginal zone B-cell lymphoma in a patient with chronic lymphocytic leukaemia

Primary cutaneous marginal zone B-cell lymphoma (PCMZL) is a low-grade malignant lymphoma that presents in the skin with no evidence of extracutaneous localization at diagnosis. We present an 80-year-old woman with B-cell chronic lymphocytic leukaemia (CLL) who developed multifocal PCMZL lesions 14 months after CLL diagnosis. PCMZL was clonally similar to the original bone marrow (BM) CLL cells. The specific translocation t(14;18) (q32;q21) with breakpoints in IGH and BCL2 loci was found in a skin specimen, but was absent in BM and peripheral blood (PB) cells. In contrast, a 13q deletion was found in BM and PB CLL cells. The patient was treated with chlorambucil and complete response of PCMZL was achieved. To our knowledge this is the first patient with CLL in whom PCMZL has been diagnosed.

Rituximab plus cladribine with or without cyclophosphamide in patients with relapsed or refractory chronic lymphocytic leukemia

OBJECTIVES

The aim of our study was to determine the feasibility, effectiveness and toxicity of combined regimens consisting of rituximab and cladribine (2-CdA) (RC) and RC plus cyclophosphamide (RCC) in the treatment of patients with recurrent or refractory chronic lymphocytic leukemia (CLL).

METHODS

The RC regimen consisted of rituximab given on day 1 and 2-CdA (days 2-6). The RCC protocol included rituximab (day 1), 2-CdA (days 2-4) and cyclophosphamide given on days 2-4. The courses were re-administered at time intervals of 4 weeks or longer if severe myelosuppression occurred.

RESULTS

Forty-six patients with CLL entered the study. Eighteen patients were treated with RC and 28 with RCC regimen. The median number of courses administered were three cycles (range 1-6). Three (6.5%) patients (95% CI: 1-14%) achieved a complete response and 31 (67%) patients (95% CI: 50-83%) a partial response. According to the particular regimen, the overall response rate was obtained in 12 (67%) patients treated with RC (95% CI: 45-89%) and in 22 patients (78%) treated with RCC (95% CI: 62-93%). The median progression free survival of responders to RC/RCC regimens was 12 months (range 4-46). Hypersensitivity to rituximab occurred in 16 (33%) patients, mostly during the first infusion of the drug. Grade 3/4 neutropenia was seen in six (13%) patients, grade 3/4 thrombocytopenia in three (9%) patients and grade 3/4 infections were observed in ten (28%) patients.

CONCLUSIONS

These data indicate that both RC and RCC regimens are feasible in heavily pretreated patients with CLL, showing also distinct therapeutic activity and relatively low toxicity, even in patients previously treated with cladribine-based protocols.

Rituximab combined with cladribine or with cladribine and cyclophosphamide in heavily pretreated patients with indolent lymphoproliferative disorders and mantle cell lymphoma

BACKGROUND

In vitro studies have shown synergistic or additive interactions between rituximab and purine nucleoside analogues. The results of recent clinical trials seem to confirm these preclinical observations.

METHODS

For the current study, the authors evaluated the feasibility, efficacy, and toxicity of combined regimens that consisted of either rituximab plus cladribine (2-CdA) (the RC regimen) or RC plus cyclophosphamide (the RCC regimen) in the treatment of patients with heavily pretreated, indolent lymphoid malignancies. Fifty-four adult patients with recurrent or refractory, low-grade non-Hodgkin lymphoma (LG-NHL) and B-cell chronic lymphocytic leukemia (B-CLL) were treated according to the RC/RCC regimens. The RC protocol consisted of intravenous rituximab at a dose of 375 mg/m(2) on Day 1 and 2-CdA at a dose of .12 mg/kg per day on Days 2 through 6. The RCC protocol consisted of rituximab at a dose of 375 mg/m(2) on Day 1, 2-CdA at a dose of 0.12 mg/m(2) on Days 2 through 4, and intravenous cyclophosphamide at a dose of 250 mg/m(2) per day on Days 2 to 4. The RC/RCC courses were repeated at 4-week intervals.

RESULTS

Thirty-three patients with B-CLL, 12 patients with LG-NHL and 9 patients with mantle cell lymphoma (MCL) entered the study. Thirty-three patients (61%) had recurrent disease after prior therapy, and 21 patients (39%) had refractory disease. Thirty-one patients were treated on the RC regimen, and 23 patients were treated on the RCC regimen. Six patients (11%) achieved a complete response, and 33 patients (60%) achieved a partial response. The median failure-free survival of responders was 10.5 months. The treatment revealed tolerability, with episodes of severe neutropenia (Grade 3 and 4 [according to World Health Organization criteria]) observed in 6 patients (11%), episodes of Grade 3 and 4 infections observed in 11 patients (20%), and episodes of Grade 3-4 thrombocytopenia observed in 4 patients (7%).

CONCLUSIONS

The RC and RCC regimens were highly effective and well tolerated modalities of treatment in heavily pretreated patients with indolent lymphoproliferative disorders.

New agents in chronic lymphocytic leukemia

For many years, alkylating agents, especially chlorambucil, have been considered the drugs of choice for first-line treatment of progressive and symptomatic chronic lymphocytic leukemia (CLL). More recently, treatment approaches have included purine nucleoside analogs (PNAs), fludarabine or cladribine (2-CdA), and monoclonal antibodies (MoAbs). PNAs are highly active in patients with CLL, previously treated and untreated. Significantly higher overall response and complete response in patients treated initially with fludarabine or 2-CdA than in those treated with chlorambucil- or cyclophosphamide-based combination regimens have been recently confirmed in prospective, randomized trials. However, the median survival times do not differ among the patients treated with PNA and alkylating agents. The MoAbs directed against CD52 antigen (alemtuzumab) and CD20 antigen (rituximab) also demonstrate significant activity in CLL and should be used in patients with disease that is refractory to PNAs. Combination therapies with PNAs and cyclophosphamide, and especially with rituximab, are more active than monotherapy with PNAs in regard to response rate and possible survival. Because most patients are older and there is no survival time advantage for alkylating agents or PNA therapies, we recommend chlorambucil as the first-line treatment, with PNAs for consideration as the second-line therapy. PNAs alone or in combination with cyclophosphamide and rituximab as first-line treatment are an option in younger patients, who may be candidates for consolidation therapy with alemtuzumab and/or stem cell transplantation. Alemtuzumab may be an effective treatment for patients refractory to PNAs. Several biological parameters have been gaining increasing importance to evaluate the prognosis of patients with CLL and define optimal therapeutic strategy. Moreover, novel therapies are being evaluated, especially in patients refractory to PNAs, including those targeting the antiapoptotic bcl-2 family of proteins and receptors, vaccines, and allogenic stem cell transplantation, especially after nonmyeloablative chemotherapy.

Dihydrodiol dehydrogenase in drug resistance and sensitivity of human carcinomas

We previously reported (UroOncology 1:165, 2001) cross-resistance and collateral-sensitivity to 2-chlorodeoxyadenosine (CldAdo) and fludarabine (FaraA), respectively, in a human renal cell carcinoma selected for resistance to 2'-deoxytubercidin (Caki-dTub). Insofar that these drugs generally demonstrate cross resistance rather than collateral sensitivity, we further examined the bases for this phenomenon. Both CldAdo and FaraA induce apoptosis, as the triphosphates, via binding to Apaf-1. In the presence of cytochrome c, this binding leads to activation of procaspase 9 to active caspase 9 that induces apoptosis through its activation of caspase 3. CldAdo and FaraA induced caspase 3 activities in wild type and Caki-dTub cell lines in a dose-dependent manner that paralleled the cross-resistance (CldAdo, 200-fold) or collateral sensitivity (FaraA, 20-fold) with regard to cell viability. The activation of caspase 3 was inhibited by the caspase 9 inhibitor, Z-LEHD-FMK, suggesting that both drugs act via the same pathway. By differential display and direct enzyme analysis, dihydrodiol dehydrogenase (DDH) was observed to be profoundly underexpressed in the Caki-dTub compared to wild-type Caki-1 cells. Stable transfection of the Caki-dTub cells with a vector encoding the enzyme led to partial reversal of the resistance to CldAdo. Resistance to cisplatin has recently been ascribed to overexpression of DDH in a human ovarian carcinoma cell line (Deng et al. in J Biol Chem 227:15035, 2002). It is tempting to speculate a mutation in the Apaf-1 nucleotide binding site that reduces (CldAdo) or increases (FaraA) toxicity in the Caki-dTub cells; however, the recent finding by others in a human ovarian carcinoma cell line suggests that DDH expression mediates the cross-resistance and perhaps, collateral-sensitivity.

Single-agent purine analogues for the treatment of chronic lymphocytic leukaemia: A systematic review and meta-analysis

BACKGROUND

Recent trials suggest improved response rates for purine analogues compared to alkylator-based regimens in the treatment of B-CLL. However, none was able to show a survival advantage. Thus, a systematic Cochrane review may be able to further define the role of purine analogues in the first-line treatment of B-CLL.

METHODS

Randomized controlled trials comparing single-agent purine analogues with alkylator-based regimens were included. Medical databases (Cochrane Library, MEDLINE, EMBASE), conference proceedings and trial registers were searched. We included full-text and abstract publications as well as unpublished data. Relative risks (RR) and hazard ratios (HR) were calculated under a fixed-effects model, clinical and statistical heterogeneity was examined with sensitivity analyses and meta-regression. If applicable, numbers needed to treat or harm (NNT, NNH) were also determined.

FINDINGS

Five trials with 1838 randomized patients were included. Importantly, four trials had a cross-over design. There was a trend for improved overall survival for patients receiving purine analogues as initial therapy but statistical significance was just not reached (HR 0.89 [95% CI 0.78-1.01]). The RR for achieving an overall (RR 1.22 [95% CI 1.13-1.31]; NNT 8 [95% CI 6-13]) and complete response (RR 1.94 [95% CI 1.65-2.28]; NNT 6 [5-8]) was significantly improved, resulting in a longer progression-free survival (HR 0.70 [95% CI 0.61-0.82]). Incidence of grade III/IV infections (RR 1.83 [95% CI 1.30-2.58]; NNH 20 [95% CI 12.5-50]) and haemolytic anaemia (RR 3.36 [95% CI 1.27-8.91]; NNH 21 [95% CI 6-185]) was significantly higher in patients receiving purine analogues.

INTERPRETATION

Despite significantly increased response rates and longer progression-free survival with purine analogues as first-line therapy, we were not able to detect a statistically significant improvement of overall survival compared to alkylator-based regimens. Furthermore, the use of purine analogues augments the risk for grade III/IV infections and haemolytic anaemia.

Purine antagonists for chronic lymphocytic leukaemia

BACKGROUND

Recent trials suggest improved response rates for purine antagonists compared to alkylator-based regimens in the treatment of B-CLL. However, none was able to show a survival advantage.

OBJECTIVES

To determine if there is any advantage of purine antagonists compared to alkylating agents (alone or in combination) in the treatment of patients with previously untreated B-CLL.

SEARCH STRATEGY

Medical databases (Cochrane Library, MEDLINE, EMBASE), conference proceedings and internet-based trial registers were searched electronically and/or by hand (1990-2003). All references were checked for further trial information. We also contacted experts in the field and pharmaceutical companies.

SELECTION CRITERIA

Randomised controlled trials comparing purine antagonists as single agents with alkylator-based regimens in patients with previously untreated B-CLL were included. We included full-text and abstract publications as well as unpublished data.

DATA COLLECTION AND ANALYSIS

Data extraction and quality assessment were done in duplicate by two independent reviewers. Missing data were obtained from original authors. Endpoints included overall survival, overall response rate, rate of complete remissions, progression-free survival, treatment-related morbidity and mortality.

MAIN RESULTS

Five trials with 1838 randomised patients were included. There is some evidence for improved overall survival after treatment with purine antagonists compared to alkylators, but statistical significance was not reached (HR 0.89 [95% CI 0.78-1.01], 4 trials, n=1638). However, the relative risk for achieving an overall response (RR 1.22 [95% CI 1.13-1.31], 5 trials, n=1751) and complete remission (RR 1.94 [95% CI 1.65-2.28], 5 trials, n=1751) was significantly higher, resulting in a longer progression-free survival (HR 0.70 [95% CI 0.61-0.82], 4 trials, n=1638). Incidence of grade III/IV infections was significantly higher in patients receiving treatment with purine antagonists (RR 1.83 [95% 1.30-2.58], 4 trials, n=1620). There was no significant difference concerning the relative risk for grade III/IV neutropenia (RR 1.14 [95% CI 0.98-1.34], 4 trials, n=1620) and therapy-related mortality (RR 0.94 [95% CI 0.45-1.95]). Overall incidence of hemolytic anemia was low, but significantly increased in the purine antagonist group (RR 3.36 [95% CI 1.27-8.91], 3 trials, n=1258).

AUTHORS' CONCLUSIONS

Despite significantly increased overall response and complete remission rates and longer progression-free survival with first-line treatment of B-CLL patients with single-agent purine antagonists, we were not able to detect a statistically significant improvement of overall survival compared to alkylator-based regimens. Furthermore, the use of purine antagonists also augments the risk for grade III/IV infections and hemolytic anemia.

Activity of Cladribine Combined with Etoposide in Heavily Pretreated Patients with Indolent Lymphoid Malignancies

We determined the effectiveness and toxicity of combined chemotherapy consisting of etoposide 100 mg/m(2)/day i.v. and cladribine (2-CdA) 0.12 mg/kg/day i.v. each for 5 days (EC regimen) in the treatment of refractory or relapsed low-grade non-Hodgkin's lymphoma and chronic lymphocytic leukemia. The cycles were repeated every 28 days, reaching a maximum of six courses. Twenty patients entered the study. All patients had received three or more cycles of chemotherapy before the EC regimen (median 8, range 3-19). Thirteen patients received 2-CdA before the EC regimen. Seven out of 20 patients (35%) responded, including one complete response. Median overall survival time of responding patients was 22 months (range 3-30). Myelosuppression and infections were the major toxicity of the EC regimen.

Therapy of chronic lymphocytic leukemia with purine analogs and monoclonal antibodies

B-cell chronic lymphocytic leukemia (CLL) is a clonal hematopoietic disorder characterized by proliferation and accumulation of small lymphocytes. It is the most common form of leukemia in North America and Europe. The management of CLL is determined by the stage and activity of the disease. Several randomized studies indicate that cytotoxic therapy based on alkylating agents in the indolent phase of disease, does not prolong the survival time of CLL patients. Chlorambucil, with or without steroids, has been for many years the drug of choice in previously untreated patients with this leukemia. Alternative treatment approaches, including new purine nucleoside analogs (PNA), such as fludarabine and 2-chlorodeoxyadenosine (cladribine) have also shown activity in CLL. The randomized studies have indicated a higher overall response, complete remission rates and longer response duration in patients treated initially with PNA than with chlorambucil or cyclophosphamide based combination regimens. These agents alone or in combinations, seem to be the treatment of choice for patients failing standard therapies. The monoclonal antibodies directed against CD52 antigen (alemtuzumab, Campath-1H) and CD20 antigen (rituximab) demonstrate also significant activity in CLL patients. These agents have significant single-agent activity, distinct mechanism of action and generally, favorable toxicity profiles. Both antibodies achieved the most promising results in the treatment of patients with relapsed or refractory CLL. More recently the effect of alemtuzumab in previously untreated patients has been also investigated and results are very encouraging. A multicenter prospective randomized study comparing alemtuzumab and chlorambucil as first line therapies are ongoing and preliminary results show acceptable toxicity profile of monoclonal antibody.

Alemtuzumab in the Treatment of Chronic Lymphocytic Leukemia

Alemtuzumab is a humanized therapeutic monoclonal antibody (MAb) that recognizes the CD52 antigen, expressed on normal and neoplastic lymphocytes, monocytes, and natural killer cells. In 2001, alemtuzumab was approved in the US and Europe to treat B-cell chronic lymphocytic leukemia (CLL) that had been treated previously with alkylating agents and was refractory to fludarabine. In heavily pretreated patients this MAb is able to produce response rates of about 40%, and in symptomatic, previously untreated patients response rates of more than 80% can be achieved. Alemtuzumab can also be used in patients with CLL as a preparative regimen for stem cell transplantation (SCT) and to prevent graft versus host disease. Moreover its in vivo use before or after SCT may also potentially result in depletion of residual leukemia cells, especially in the autologous setting. Adverse events associated with alemtuzumab include acute first-dose reaction, hematologic toxicity, and infectious complications. Usually they are predictable, manageable, and acceptable in the context of CLL. However, in a significant percentage of patients, cytomegalovirus reactivation occurs during alemtuzumab therapy, and routine weekly monitoring with the polymerase chain reaction methodology is indicated. Moreover, antiviral and antibacterial prophylaxis is mandatory.

Therapy of Chronic Lymphocytic Leukaemia with Purine Nucleoside Analogues

Chronic lymphocytic leukaemia (CLL) is a neoplastic disease of unknown aetiology characterised by an absolute lymphocytosis in peripheral blood and bone marrow. The disease is diagnosed most commonly in the elderly with the median age at diagnosis being about 65 years. The purine nucleoside analogues (PNAs) fludarabine, cladribine (2-chlorodeoxyadenosine) and pentostatin (2'-deoxycoformycin) are highly active in CLL, both in previously treated and in refractory or relapsed patients. These three agents share similar chemical structures and mechanisms of action such as induction of apoptosis. However, they also exhibit significant differences, especially in their interactions with enzymes involved in adenosine and deoxyadenosine metabolism. Recent randomised studies suggest that fludarabine and cladribine have similar activity in CLL. However, clinical observations indicate the existence of cross-resistance between fludarabine and cladribine. Patients who received PNAs as their initial therapy and achieved long-lasting response can be successfully retreated with the same agent. PNAs administered in combination with other chemotherapeutic agents and/or monoclonal antibodies may produce higher response rates, including complete response (CR) or molecular CR, compared with PNAs alone or other treatment regimens. Management decisions are more difficult in elderly patients because of the apparent increase in toxicity of PNAs in this population. In elderly patients, we recommend chlorambucil as the first-line treatment, with PNAs in lower doses in refractory or relapsed patients. Myelosuppression and infections, including opportunistic varieties, are the most frequent adverse effects in patients with CLL treated with PNAs. Therefore, some investigators recommend routine antibacterial and antiviral prophylaxis during and after PNA treatment. This review presents current results and treatment strategies with the use of PNAs in CLL, especially in elderly patients.

The place of cladribine in the treatment of chronic lymphocytic leukemia: a 10-year experience in Poland

Cladribine (2-CdA) is structurally similar to another purine analog, fludarabine (FA), recently accepted in several centers as the first-line treatment in chronic lymphocytic leukemia (CLL). Unfortunately, there is less experience with the use of 2-CdA than with FA in patients with CLL in the majority of Western countries. In the last decade we performed several phase II studies and two phase III randomized trials to evaluate the activity and toxicity of 2-CdA in previously treated and untreated patients with CLL. We have also compared the results of Polish studies with the data presented by other investigators. Similarly to FA this agent has been found to be more effective in previously untreated CLL than in patients refractory to or relapsed after conventional therapy with alkylating agents. In different studies the overall response (OR) rate ranged from 70 to 85% and complete response (CR) from 10 to 47%. Higher CR and OR rates in CLL patients treated with 2-CdA and prednisone than with chlorambucil and prednisone were confirmed in our multicenter, randomized study. Subsequently, we performed a multicenter, randomized study comparing 2-CdA alone with a combination of 2-CdA and cyclophosphamide (CC) or cyclophosphamide and mitoxantrone (CMC). Our updated results seem to indicate that the CC program used as a first-line therapy in CLL gives higher CR and OR and better elimination of minimal residual disease (MRD) than 2-CdA alone. CC is also less myelotoxic than CMC. More recently, we have undertaken a phase II study to determine the efficacy and toxicity of 2-CdA combined with the anti-CD20 monoclonal antibody rituximab in CLL and other refractory or relapsed indolent lymphoproliferative disorders. The preliminary results seem to be better than in similar patients previously treated in our institution with 2-CdA alone. In conclusion, the studies performed in the last decade in Poland and other countries have shown that 2-CdA used alone or in combination with other agents is, similarly to FA, a highly active and relatively safe agent in previously treated and untreated patients with CLL.

Equilibrative nucleoside transporter-2 (hENT2) protein expression correlates with ex vivo sensitivity to fludarabine in chronic lymphocytic leukemia (CLL) cells

Fludarabine is considered the treatment of choice for most patients with chronic lymphocytic leukemia (CLL). We have analyzed the role of plasma membrane transporters in nucleoside-derived drug bioavailability and action in CLL cells. Among the known plasma membrane transporters, we have previously observed a significant correlation between fludarabine uptake via ENT carriers and ex vivo sensitivity of CLL cells to fludarabine, although mRNA amounts of the equilibrative nucleoside transporters hENT1 and hENT2 do not show any predictive response to treatment. In this study, using polyclonal monospecific antibodies we have observed a significant correlation between the expression of hENT2 by Western blot and fludarabine uptake via hENT carriers and also with ex vivo sensitivity of CLL cells to fludarabine. These results suggest that the equilibrative nucleoside transporter hENT2 plays a role in fludarabine responsiveness in CLL patients.

The clinical and epidemiological burden of chronic lymphocytic leukaemia

The purpose of this literature review was to identify and summarize published studies describing the epidemiology and management of chronic lymphocytic leukaemia (CLL). Chronic lymphocytic leukaemia represents 22-30% of all leukaemia cases with a worldwide incidence projected to be between < 1 and 5.5 per 100,000 people. Australia, the USA, Ireland and Italy have the highest CLL incidence rates. Chronic lymphocytic leukaemia presents in adults, at higher rates in males than in females and in whites than in blacks. Median age at diagnosis is 64-70 years. Five-year survival rate in the USA is 83% for those < 65 years old and 68% for those 65 + years old. Hereditary and genetic links have been noted. Persons with close relatives who have CLL have an increased risk of developing it themselves. No single environmental risk factor has been found to be predictive for CLL. Patients are usually diagnosed at routine health care visits because of elevated lymphocyte counts. The most common presenting symptom of CLL is lymphadenopathy, while difficulty exercising and fatigue are common complaints. Most patients do not receive treatment after initial diagnosis unless presenting with clear pathologic conditions. Pharmacological therapy may consist of monotherapy or combination therapy involving glucocorticoids, alkylating agents, and purine analogs. Fludarabine may be the most effective single drug treatment currently available. Combination therapy protocols have not been shown to be more effective than fludarabine alone. As no cure is yet available, a strong unmet medical need exists for innovative new therapies. Experimental treatments under development include allogeneic stem cell transplant, mini-allogeneic transplants, and monoclonal antibodies (e.g. alemtuzumab against CD52; rituximab against CD20).