Lack of effect of 2-chlorodeoxyadenosine therapy in patients with chronic lymphocytic leukemia refractory to fludarabine therapy

Sepsis due to Erysipelothrix rhusiopathiae in a patient with chronic lymphocytic leukemia associated with bronchopneumonia due to Pseudomonas aeruginosa and Escherichia coli: A case report

INTRODUCTION

The present report describes a case of sepsis due to Erysipelothrix rhusiopathiae in a patient with B-cell chronic lymphocytic leukemia with no animal exposure, associated with concomitant bronchopneumonia due to Pseudomonas aeruginosa and Escherichia coli.

CASE PRESENTATION

A 54-year-old Caucasian man presented to an emergency room with a three-day history of chest pain, fever, cough with purulent sputum, chills and dyspnea. The patient had associated erythematous papules on the chest and enlarged axillary, submandibular, pectoral and supraclavicular lymph nodes, which regressed under treatment with penicillin. The patient was found to have sepsis without endocarditis caused by E rhusiopathiae, associated with bronchopneumonia that was induced by a double Gram-negative infection.

CONCLUSIONS

The underlying-B cell chronic lymphocytic leukemia may have favoured the development of bacteremia due to E rhusiopathiae, which occurred subsequent to glossitis in an immunocompromised host being treated with methylprednisolone and cladribine.

Beyond hairy cell: the activity of cladribine in other hematologic malignancies

Before the contemporary development of rationally designed antineoplastic therapies, cladribine was identified as a lymphocyte-specific agent. Its profound impact on the natural history of hairy cell leukemia, with responses approaching 100% and a median duration of response of nearly a decade after only a single 7-day course, is well known and revolutionized the treatment of hairy cell leukemia. However, cladribine's impressive activity in other lymphoproliferative disorders has been generally underappreciated. Multiple single-arm phase 2 trials have demonstrated cladribine's potency across the full spectrum of lymphoid malignancies. In a limited number of phase 3 trials and cross-study analyses, cladribine compared favorably with fludarabine, another purine nucleoside analog that is more commonly used in the treatment of indolent lymphoid malignancies. Cladribine has been noted to have particular activity among lymphoid disorders with few effective therapies, specifically, chronic lymphocytic leukemia, lymphoplasmacytic lymphoma, marginal zone lymphoma, and mantle cell lymphoma. Recently approved novel agents may act in synergy with cladribine for these conditions and should be incorporated into future clinical studies.

Treatment of patients with fludarabine-refractory chronic lymphocytic leukemia: need for new treatment options

Fludarabine-refractory chronic lymphocytic leukemia is associated with poor survival rates. Chemoimmunotherapy combinations that include purine analogs, alkylating agents, and monoclonal antibodies have shown the highest response rates to date. Intensive treatment approaches can be associated with poor tolerability that is often characterized by deteriorating immune functions and high infection rates. Treatment with some monoclonal antibodies is often complicated by infusion-related adverse events and increased risk of infections. Several novel agents are currently being investigated for this difficult-to-treat patient population. Ofatumumab is an anti-CD20 monoclonal antibody that targets a different epitope from the one targeted by rituximab and, it has shown promising antileukemia activity. Lenalidomide is an immunomodulatory agent that has shown promising activity in patients with fludarabine-refractory chronic lymphocytic leukemia, many of whom had poor prognostic features and bulky disease. Encouraging results have been observed with each of these agents individually. However, given the diverse mechanisms governing CLL pathogenesis and disease progression, ongoing clinical trials combinations of these agents may improve clinical outcomes for this patient population.

Cladribine: not just another purine analogue?

Cladribine was synthesized as a purine analogue drug that inhibited adenosine deaminase. It received FDA approval in the 1980s for treatment of hairy cell leukemia. Given its toxicity towards lymphocytes and its corresponding immunosuppressive effects, it has been studied and found efficacious in a variety of hematologic malignancies and autoimmune conditions, most recently multiple sclerosis. This review highlights pharmacological, toxicological and clinical data for the use of cladribine. It also discusses existing and new mechanisms that may contribute to its unique clinical activity. Emerging data show that in addition to its known purine nucleoside analogue activity, cladribine possesses epigenetic properties, inhibiting S-adenosylhomocysteine hydrolase and DNA methylation. This may contribute to its efficacy and highlights the importance of studying combination therapy with other epigenetic or targeted agents. Clinical trials are underway in a variety of malignant and nonmalignant conditions.

Drug cross-resistance and therapy-induced resistance in chronic lymphocytic leukaemia by an enhanced method of individualised tumour response testing

Previous results with individualised tumour response testing (ITRT) in vitro in chronic lymphocytic leukaemia (CLL) have consistently shown good correlation with patient response and survival. We describe here an improved test and report its use with samples from the Leukaemia Research Fund CLL4 randomised clinical trial and previously treated patients. ITRT was performed by the tumour response to anti-neoplastic compounds (TRAC) assay, a modification of the differential staining cytotoxicity (DiSC) assay. Improvements included drying drugs into wells before assay and using the Octospot system to cytocentrifuge eight spots of cells onto one microscope slide. We successfully tested 765/782 (98%) cellular blood samples received within 48 h of phlebotomy. Cross-resistance (Pearson's r > 0.7) in untreated CLL was found between similar drugs. Mitoxantrone (r = 0.31), cyclophosphamide (r = 0.35) and pentostatin (r = 0.29) had low cross-resistance with fludarabine. Treatment resulted in increased resistance to chlorambucil, cyclophosphamide, doxorubicin, mitoxantrone, corticosteroids, cladribine and fludarabine (P < 0.01) but not to pentostatin. These results provide further rationale for standard drug combinations such as fludarabine-mitoxantrone and fludarabine-mitoxantrone-cyclophosphamide and suggest possible pentostatin salvage in fludarabine-resistant patients. ITRT results could assist both in determining the best treatment for individual patients and in the design and rationale of future clinical trials.

Drug induction apoptosis assay as predictive value of chemotherapy response in patients with B-cell chronic lymphocytic leukemia

A large number of prognostic factors are available to help predict the course of the disease for patients with B-cell chronic lymphocytic leukemia (B-CLL). However, it is not clear the involvement of these well established prognostic factors in the clinical response of the patients with B-CLL to the chemotherapy. The possible association of the patient clinical-biological characteristics and the in vitro response to chemotherapic agents may serve to provide powerful predictive information to identify optimum treatment for patients. An apoptosis induction assay displays the patient in vitro responses to chemotherapy and the possible association with their clinical-biological characteristics. In this study, patients showed a significant better in vitro response to drugs when they were in the initial stages of the disease or with low beta(2) microglobulin serum level. Response to purine analogues was significantly higher in patients with long lymphocyte doubling time (LDT), few cells expressing CD38, normal karyotype or no p53 deletion, whereas there was no correspondence with ZAP-70 expression. Furthermore, a good correlation was shown between in vitro apoptosis induction assay and the patient clinical response to purine analogues. In conclusion, association between in vitro drug sensitivity and some of the markers considered as prognostic factors could help to develop personalised therapeutic regimens for patients with B-CLL.

Alemtuzumab in the treatment of fludarabine refractory B-cell chronic lymphocytic leukemia (CLL)

The introduction of immunotherapeutic agents has provided renewed hope for Chronic lymphocytic leukemia fludarabine-refractory patients. Several clinical trials have shown that alemtuzumab is a more effective option compared to combination chemotherapy for treatment of patients who have relapsed or who are refractory to fludarabine, including those with poor prognostic factors. Although there are significant potential toxicities associated with alemtuzumab, such as infusional reactions and the risk of cytomegalovirus (CMV) reactivation, most are manageable. Pre-treatment anti-pyretics and anti-histamines are recommended to prevent or mitigate the acute infusional reactions associated with intravenous infusion. Recent use of alemtuzumab via the subcutaneous route has been shown to be well tolerated and has yielded similar response rates to the infusional method of administration. Prophylaxis with thrimethoprim/sulphamethoxazole (TMP/SMZ) as well as valacyclovir or a similar anti-viral can prevent many of the opportunistic infections seen in early trials. Reactivation of CMV infection can be effectively managed with monitoring and early treatment. Chemo-immunotherapy combination with alemtuzumab has been tested and demonstrated unprecedented clinical results in relapsed and refractory patients. The use of this agent earlier in the algorithm of patients with these characteristics should be considered. Future areas of research will include the use of alemtuzumab in combination with other monoclonal antibodies and other targeted therapies.

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.

Role of fludarabine in hematological malignancies

Fludarabine is a prodrug that is converted to the free nucleoside 9-beta-D-arabinosyl-2-fluoroadenine (F-ara-A), which enters cells and accumulates mainly as the 5'-triphosphate, F-ara-ATP. F-ara-ATP has multiple mechanisms of action, which are mostly directed toward DNA. Collectively, these actions affect DNA synthesis, which is the major mechanism of F-ara-A-induced cytotoxicity. Secondarily, incorporation into RNA and inhibition of transcription has been shown in cell lines. As a single agent, fludarabine has been effective for indolent leukemia. Biochemical modulation strategies resulted in enhanced accumulation of cytarabine triphosphate and led to the use of fludarabine for the treatment of acute leukemia. The combination of fludarabine with DNA-damaging agents to inhibit DNA repair processes has been highly effective for indolent leukemia and lymphomas. Other strategies have incorporated fludarabine into preparative regimens for nonmyeloablative stem-cell transplantation.

Phase II study of single-agent bortezomib for the treatment of patients with fludarabine-refractory B-cell chronic lymphocytic leukemia

Therapeutic options are limited and the prognosis is poor for patients with fludarabine-refractory B-cell chronic lymphocytic leukemia (CLL). Bortezomib induces apoptosis in vitro in CLL cells, both alone and in combination, including in cells resistant to fludarabine or other agents. The aim of the current randomized, open-label, Phase II study was to investigate the clinical activity of bortezomib in patients with fludarabine-refractory B-cell CLL. Twenty-two patients with histologically confirmed B-cell CLL were treated with bortezomib at doses of 1.0 mg/m2, 1.3 mg/m2, or 1.5 mg/m2 on Days 1, 4, 8, and 11 of a 21-day treatment cycle for a maximum of 9 cycles. None of 19 patients evaluable for response achieved complete remission or partial response; however, signs of biologic activity based on disease site responses (e.g., reduction in lymphocytosis, splenomegaly, and lymphadenopathy) were observed. In the 1.5 mg/m2 dose group, a higher proportion of patients had stable disease, and a lower proportion had progressive disease compared with the 2 lower-dose groups. Eleven patients, all in the 2 higher dose groups, experienced Grade 3/4 adverse events (AEs) (according to National Cancer Institute Common Toxicity Criteria [version 2.0]); 2 patients experienced Grade 4 neutropenia. Grade 3 hematologic AEs included anemia, neutropenia, thrombocytopenia, and hemolytic anemia; Grade 3 nervous system AEs included aphasia; peripheral neuropathy, not otherwise specified; and peripheral sensory neuropathy. Although no objective responses were achieved in patients with fludarabine-refractory B-cell CLL, single-agent bortezomib demonstrated biologic activity. In view of the evidence for its activity, further exploration of bortezomib in combination with other agents is warranted.

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.

Purine nucleoside analogues and combination therapies in B-cell chronic lymphocytic leukemia: dawn of a new era

Purine nucleoside analogues are unique drugs that are effective in a variety of hematologic malignancies. Fludarabine and 2-chlorodeoxyadenosine (2-CdA) are active in chronic lymphocytic leukemia (CLL) both as salvage therapy and in newly diagnosed patients. These agents have revolutionized therapeutic strategies for patients with CLL that had remained unchanged for many years and included alkylating agents-based therapy with no potential for long-term remission or cure. Purine analogues have also been successfully combined with a variety of other chemotherapeutic drugs such as mitoxantrone, cyclophosphamide, corticosteroids, and monoclonal antibodies, specifically Rituximab and CAMPATH-1H. These agents are immunosuppressive and have been associated with opportunistic infections, the incidence of which can be significantly reduced by early recognition and administration of prophylactic antibiotics. In this review, the activity and toxicity of 2-CdA, fludarabine, and pentostatin in CLL as single agents and in combination with conventional chemotherapy are discussed. These drugs are increasingly used as initial therapy in CLL. Such strategies are associated with higher remission rates than have been previously achieved and in some cases, molecular remission, suggesting an important step towards cure.

Treatment for Waldenstrom’s macroglobulinemia

Waldenstrom's macroglobulinemia is a rare form of indolent lymphoma characterized by the production of a monoclonal immunoglobulin M protein, and complications such as hyperviscosity, cytopenias and peripheral neuropathy. Conventional treatment approaches are based on alkylators or nucleoside analogs, but in the absence of a clearly superior regimen, a broad array of alternative therapies exists. Choices range from biological agents to combination chemotherapy to stem-cell transplantation. A rational approach therefore must be based on careful patient assessment and individualization of therapy.

Chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) is one of the most commonly diagnosed leukemias managed by practicing hematologists. For many years patients with CLL have been viewed as similar, with a long natural history and only marginally effective therapies that rarely yielded complete responses. Recently, several important observations related to the biologic significance of V(H) mutational status and associated ZAP-70 overexpression, disrupted p53 function, and chromosomal aberrations have led to the ability to identify patients at high risk for early disease progression and inferior survival. Concurrent with these investigations, several treatments including the nucleoside analogues, monoclonal antibodies rituximab and alemtuzumab have been introduced. Combination of these therapies in clinical trials has led to high complete and overall response rates when applied as initial therapy for symptomatic CLL. Thus, the complexity of initial risk stratification of CLL and treatment has increased significantly. Furthermore, when these initial therapies do not work, approach of the CLL patient with fludarabine-refractory disease can be quite challenging. This session will describe the natural history of a CLL patient with emphasis on important decision junctures at different time points in the disease. In Section I, Dr. Stephan Stilgenbauer focuses on the discussion that occurs with CLL patients at their initial evaluation. This includes a review of the diagnostic criteria for CLL and prognostic factors utilized to predict the natural history of the disease. The later discussion of risk stratification focuses on molecular and genomic aberrations that predict rapid progression, poor response to therapy, and inferior survival. Ongoing and future efforts examining early intervention strategies in high risk CLL are reviewed. In Section II, Drs. Ian Flinn and Jesus G. Berdeja focus on the discussion of CLL patients when symptomatic disease has developed. This includes an updated review of monotherapy trials with nucleoside analogs and recent trials that have combined these with monoclonal antibodies and/or alternative chemotherapy agents. Appropriate application of more aggressive therapies such as autologous and allogeneic immunotherapy and less aggressive treatments for appropriate CLL patient candidates are discussed. In Section III, Dr. John Byrd focuses on the discussion that occurs with CLL patients whose disease is refractory to fludarabine. The application of genetic risk stratification in choosing therapy for this subset of patients is reviewed. Available data with conventional combination based therapies and monoclonal antibodies are discussed. Finally, alternative promising investigational therapies including new antibodies, kinase inhibitors (CDK, PDK1/AKT, PKC) and alternative targeted therapies (DNA methyltransferase inhibitors, histone deacetylase inhibitors, etc.) are reviewed with an emphasis on the most promising agents for this patient population.

Treatment recommendations in Waldenstrom's macroglobulinemia: consensus panel recommendations from the Second International Workshop on Waldenstrom's Macroglobulinemia

This presentation represents consensus recommendations for the treatment of patients with Waldenstrom's macroglobulinemia (WM), which were prepared in conjunction with the second International Workshop held in Athens, Greece during September 2002. The faculty adopted the following statements for the management of patients with Waldenstrom's macroglobulinemia: (1) Alkylating agents, nucleoside analogues, and rituximab are reasonable choices for first line therapy of WM. (2) Both cladribine and fludarabine are reasonable choices for the therapy of WM. (3) Combinations of alkylating agents, nucleoside analogues, or rituximab should at this time be encouraged in the context of a clinical trial. (4) In WM, rituximab can cause a sudden rise in serum IgM and viscosity levels in certain patients, which may lead to complications, therefore close monitoring of these parameters and symptoms of hyperviscosity is recommended for WM patients undergoing rituximab therapy. (5) For relapsed disease, it is reasonable to use an alternate first line agent or re-use of the same agent; however, since autologous stem cell transplantation may have a role in treating patients with relapsed disease it is recommended that for patients in whom autologous transplantation is seriously being considered, exposure to alkylator or nucleoside analogue drugs should be limited. (6) Combination chemotherapy for patients who can tolerate myelotoxic therapy, thalidomide alone or with dexamethasone, can reasonably be considered to have relapsed. (7) Autologous stem cell transplantation may be considered for patients with refractory or relapsing disease. (8) Allogeneic transplantation should only be undertaken in the context of a clinical trial. (9) Plasmapheresis should be considered as interim therapy until definitive therapy can be initiated. (10) Rituximab should be considered for patients with IgM-related neuropathies. (11) Corticosteroids may be useful in the treatment of symptomatic mixed cryoglobulinemia. (12) Splenectomy is rarely indicated but has been used to manage painful splenomegaly and hypersplenism.

A phase II study of cladribine treatment for fludarabine refractory B cell chronic lymphocytic leukemia: results from CALGB Study 9211

Cladribine has been reported to have little activity in fludarabine- refractory chronic lymphocytic leukemia (CLL). We sought to determine whether resistance to therapy with cladribine in fludarabine-refractory CLL patients represented primary drug resistance or the inability to tolerate the myelosuppression associated with this therapy. Patients with fludarabine refractory CLL patients without severe thrombocytopenia (platelets >/=50 x 10(9)/l) or granulocytopenia (neutrophils >1.5 x 10(9)/l) were enrolled. All patients received cladribine (0.14 mg/kg) as a 2-h intravenous infusion daily for 5 days, repeated every 4 weeks. Patients received up to six cycles of therapy. Twenty-eight patients enrolled; 13 had intermediate (Rai stage I or II) and 15 high (Rai stage III and IV) risk stages. No patient had a complete remission, but nine (32%; 95% confidence interval, 15-49%) attained a partial remission when assessed using the modified NCI criteria (1996). The median time to relapse for responders was 12 months, while median progression-free survival for the entire group was 9 months (95% confidence interval, 4-14 months). The median overall survival was 2.2 years (95% confidence interval, 0.8-3.1 years). Response was predicted by pre-treatment Rai status with seven of 13 (54%) intermediate risk vs two of 15 (13%) high-risk patients responding (P = 0.04). Toxicity was myelosuppression and infections (grade 3-5: neutropenia 75%, thrombocytopenia 68%, and infections 43%). Cladribine has modest clinical activity and considerable toxicity in a very selected group of patients with fludarabine-refractory CLL lacking pre-treatment neutropenia and thrombocytopenia.

B-chronic lymphocytic leukemia: practical aspects

B-CLL is the most common adult leukemia in the Western world. It is a neoplasia of mature looking B-monoclonal lymphocytes co-expressing the CD5 antigen (involving the blood, the bone marrow, the lymph nodes and related organs). Much new information about the nature of the neoplastic cells, including chromosomal and molecular changes as well as mechanisms participating in the survival of the leukemic clone have been published recently, in an attempt to elucidate the biology of the disease and identify prognostic subgroups. For the time being, clinical stage based on Rai and Binet staging systems remains the strongest predictor of prognosis and patients' survival, and therefore it affects treatment decisions. In the early stages treatment may be delayed until progression. When treatment is necessary according to well-established criteria, there are nowadays many different options. Chlorambucil has been the standard regimen for many years. During the last decade novel modalities have been tried with the emphasis on fludarabine and 2-chlorodeoxyadenosine and their combinations with other drugs. Such an approach offers greater probability of a durable complete remission but no effect on overall survival has been clearly proven so far. Other modalities, included in the therapeutic armamentarium, are monoclonal antibodies, stem cell transplantation (autologous or allogeneic) and new experimental drugs. Supportive care is an important part of patient management and it involves restoring hypogammaglobulinemia and disease-related anemia by polyvalent immunoglobulin administration and erythropoietin respectively.

Results of first salvage therapy for patients refractory to a fludarabine regimen in chronic lymphocytic leukemia

Resistance to purine analogs is emerging as a major problem in the management of patients with chronic lymphocytic leukemia (CLL). Most of these patients have already been exposed to and have become refractory to alkylating agents. To define the natural history of fludarabine (Fludara) refractory patients with CLL, we reviewed the response to first salvage therapy of 147 patients who were refractory to Fludara or had a remission less than six months in duration after a Fludara-containing regimen. Thirty-three (22%) patients responded to their first salvage attempt. However, the median survival was only 10 months. Responders survived significantly longer than non-responders. The most effective salvage regimens were combinations of purine analogs and cyclophosphamide. Patients still possibly sensitive to alkylating agents had a superior response than alkylating agent resistant or naive patients. Subsequent salvage therapy was administered to 61 patients. The most promising results noted in the group were transplantation and the use of Campath-1H antibody. The major morbidity and cause of death were associated with infections. The probability of infection was most strongly associated with the response to salvage therapy. Gram-positive organisms were most commonly associated with infection. However, gram-negative bacilli or opportunistic infection such as fungi, Pneumocystis carinii, acid-fast bacilli and legionella were prominent causes of infection. Fludara-refractory patients are a poor prognosis group and need more effective therapeutic regimens and well-designed infection prophylactic regimens.

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

Chronic lymphocytic leukemia (CLL) is the most common form of leukemia in the Western world. The natural clinical course is highly variable and chemotherapy is usually not indicated in early and stable disease. Treatment is needed in the progressive form of this leukemia. Chlorambucil, with or without steroids, has been for many years the drug of choice in the treatment of CLL. More recently, treatment approaches have included nucleoside analogues, (NA) fludarabine (FAMP) and cladribine (2-CdA, 2-chlorodeoxyadenosine), which seem to be the treatment of choice for patients failing standard therapies. Their role as first line therapy is being investigated in randomized trials and the results have recently been published. These studies have shown a higher overall response and complete remission (CR) rate and longer response duration in patients treated initially with NA than with chlorambucil or cyclophosphamide-based combination regimens. In contrast, overall survival is similar in patients treated with NA and alkylating agents. However, the randomized trials were designed as crossover studies which may influence survival. Combined use of NA with other cytotoxic drugs, cytokines, monoclonal antibodies and other agents may increase the CR and prolong survival time. However, the results of randomized trials comparing combination treatment with NA alone are not yet available. In conclusion, alkylating agents still have an important place in the routine management of the majority of CLL patients. NA should be routinely used as second line treatment and possibly as first line therapy in younger patients, who are candidates for potentially curative treatment such as stem cell transplantation and/or monoclonal antibodies.

Resistance of leukemic cells to 2-chlorodeoxyadenosine is due to a lack of calcium-dependent cytochrome c release

The purine nucleoside 2-chlorodeoxyadenosine (CdA) is often used in leukemia therapy. Its efficacy, however, is compromised by the emergence of resistant cells. In the present study, 3 CdA-resistant cell lines were generated and characterized. Their ability to accumulate 2-chloroadenosine triphosphate (CdATP) varied, reflecting differences in activities of deoxycytidine kinase (dCK) and deoxyguanosine kinase (dGK). Nonetheless, the selected lines were uniformly resistant to CdA-induced apoptosis, as assessed by caspase activation and DNA fragmentation. In contrast, cytosols from resistant cells were capable of robust caspase activation when incubated in the presence of cytochrome c and dATP. Moreover, replacement of dATP with CdATP also resulted in caspase activation in the parental and some of the resistant cell lines. Strikingly, CdA-induced decreases in mitochondrial transmembrane potential and release of cytochrome c from mitochondria were observed in the parental cells but not in any resistant lines. The lack of cytochrome c release correlated with an increased ability of mitochondria from resistant cells to sequester free Ca2+. Consistent with this enhanced Ca2+ buffering capacity, an early increase in cytosolic Ca2+ after CdA treatment of parental cells but not resistant cells was detected. Furthermore, CdA-resistant cells were selectively cross-resistant to thapsigargin but not to staurosporine- or Fas-induced apoptosis. In addition, CdA-induced caspase-3 activation and DNA fragmentation were inhibited by the Ca2+ chelator BAPTA-AM in sensitive cells. Taken together, the data indicate that the mechanism of resistance to CdA may be dictated by changes in Ca2+-sensitive mitochondrial events.

Cladribine in the treatment of chronic lymphocytic leukemia

Cladribine (2-chlorodeoxyadenosine, 2-CdA) is a nucleoside analog with substituted halogen atom at position 2 in its purine ring that makes it resistant to deamination by adenosine deaminase (ADA). 2-CdA is the drug of choice in the treatment of hairy cell leukemia, but it is also highly active in other low grade lymphoid malignancies including chronic lymphocytic leukemia (CLL). The results of the studies presented so far have shown that 2-CdA gives similar complete response (CR) rate and overall response (OR) rate to fludarabine but the influence of both agents on survival times of the patients with CLL is still uncertain. CR rate induced with 2-CdA is significantly higher than in the patients treated with conventional chemotherapy. In refractory or relapsed patients 2-CdA induces 31 to 68% of overall responses including CR in 4 to 31%. In previously untreated patients overall remission rates of about 56-82% have been achieved with 2-CdA alone. When 2-CdA was used as primary therapy the CR rate was also significantly higher and ranged from 10% to 47%. Patients who received 2-CdA as their initial therapy and experienced a response lasting at least a year may be successfully treated subsequently with the same agent. A second response has been achieved in 35 to 100% patients treated with this agent for the second time. Despite the fact that 2-CdA gives higher CR and OR rates than conventional chemotherapy, it has not been established whether it has any influence on survival time. However, cross resistance between 2-CdA and FAMP in CLL patients is evident in the majority of studies. Bone marrow suppression with anemia neutropenia and thrombocytopenia are the dose limiting factors for 2-CdA use. These side effects are pronounced in heavily pretreated patients and after multiple courses of therapy. Treatment with this agent also leads to the decrease of the CD4+/CD8+ ratio for an extensive period of time exceeding 12, even up to 24 months. In consequence, infections including opportunistic type, are frequently observed. We suggest, that in patients with CLL, 2-CdA should be used as second line treatment rather than the first line therapy until the final results of ongoing randomized clinical trials are available.

Achieving Optimal Outcomes in Chronic Lymphocytic Leukaemia

Chronic lymphocytic leukaemia (CLL) is a disease of late middle age and older. The majority of patients are diagnosed because of a lymphocytosis of at least 5 x 10(9)/L on an incidental blood count. It needs to be distinguished from mantle cell lymphoma and splenic marginal zone lymphoma by lymphocyte markers. The immunophenotype of CLL is sparse surface immunoglobulin, CD5+, CD19+, CD23+, CD79b-, and FMC7-. The disease is staged according to the presence of lymphadenopathy and/or splenomegaly and the features of bone marrow suppression. Most patients have an early stage of disease when diagnosed and perhaps 50% will never progress. This group of patients have a normal life expectancy and do not require treatment beyond reassurance. Progression involves an increasing white cell count, enlarging lymph nodes and spleen, anaemia and thrombocytopenia. Complications of progression include autoimmune haemolytic anaemia and thrombocytopenia, immunodeficiency, and the development of a more aggressive lymphoma. A range of prognostic factors is available to predict progression, but most haematologists rely on close observation of the patient. Intermittent chlorambucil remains the first choice treatment for the majority of patients. Combination chemotherapy offers no advantage. Intravenous fludarabine is probably more effective than chlorambucil, but no trial has yet shown a survival advantage for using it first rather than as a salvage treatment in patients not responding to chlorambucil. It is at least 40 times as expensive as chlorambucil. Cladribine may be as effective as fludarabine, although it has been used less and is even more expensive. Patients who relapse after chlorambucil should be offered retreatment with the same agent and if refractory should be switched to fludarabine, which may also be offered for retreatment on relapse. For patients refractory to both drugs, a variety of options are available. High dose corticosteroids, high dose chlorambucil, CHOP (cyclophosphamide, prednisolone, vincristine and doxorubicin), anti-CD52, anti-CD20 and a range of experimental drugs which are being evaluated in clinical trials. Younger patients should be offered the chance of treatment with curative intent, preferably in the context of a clinical trial. Autologous stem cell transplantation after achieving a remission with fludarabine has relative safety and may produce molecular complete remissions. Only time will tell whether some of these patients are cured but it seems unlikely. Standard allogeneic bone marrow transplant is probably too hazardous for most patients, but non-myeloablative regimens hold out the hope of invoking a graft-versus-leukaemia effect without a high tumour-related mortality. Trials of immunotherapy are exciting options for a few patients in specialised centres.

Infection and immunity in chronic lymphocytic leukemia

Patients having chronic lymphocytic leukemia (CLL) are at increased risk for infectious morbidity and mortality. The predisposition to infections in CLL patients has many components, including both immunodeficiency related to the leukemia itself (humoral and cellular immune dysfunction) and the results of cumulative immunosuppression related to CLL treatment. The risk of infectious complications increases with the duration of CLL, reflecting the natural history of the disease and the cumulative immunosuppression related to its treatment. Hence, in early, untreated CLL, the infectious risk is mainly related to hypogammaglobulinemia, and infections by encapsulated bacteria are common. However, in patients having advanced CLL, particularly those who receive the newer purine analogues, neutropenia and defects in cell-mediated immunity appear to be the major predisposing factors. An expanded spectrum of pathogens, including opportunistic fungi, Pneumocystis carinii, Listeria monocytogenes, mycobacteria, and herpesviruses, are seen in that setting. The changing spectrum of infections in this latter group of patients mandates a newer approach to prophylaxis and therapy.

Phase I/II study of 2-chloro-2'-deoxyadenosine with cyclophosphamide in patients with pretreated B cell chronic lymphocytic leukemia and indolent non-Hodgkin's lymphoma

Because of their substantial in vitro synergy, we conducted a dose-escalation study of cyclophosphamide (CP) added to 2-chloro-2'-deoxyadenosine (CdA) in patients with previously treated chronic lymphocytic leukemia and non-Hodgkin's lymphoma. CdA was given at a fixed dose (5.6 mg/m2/day) as a 2-h intravenous (i.v.) infusion, immediately followed by a 1-h i.v. infusion of CP, for 3 days. The initial daily CP dose was 200 mg/m2, and was escalated by 100 mg/m2 increments in successive cohorts of three to six patients to determine the maximum-tolerated dose (MTD). Additional patients were included at the MTD to extend toxicity and response analysis. Twenty-six patients received 68 cycles of chemotherapy. The MTD of CP after CdA 5.6 mg/m2, was 300 mg/m2. Acute neutropenia was the dose-limiting toxicity of this regimen, which was otherwise well tolerated. Delivery of repeated cycles was not feasible in eight patients (31%) because of prolonged thrombocytopenia. Severe infections were seen in three of 68 cycles (4%). The overall response rate was 58% (15 of 26; 95% CI, 36-76%), with 15% complete responses and 42% partial responses. These data show the feasibility of the association of CdA with CP. Given the response rate observed, further studies of this regimen are warranted in untreated patients, in particular with chronic lymphocytic leukemia and with Waldenström macroglobulinemia.

Allogeneic bone marrow transplantation for low-grade lymphoma and chronic lymphocytic leukemia

Twenty-six patients with low-grade lymphoma (LGL) (n = 18) or chronic lymphocytic leukemia (CLL) (n = 8) received allogeneic BMTs between 1985 and 1998. Median age was 42 years, median interval from diagnosis to transplant 22 months and median number of prior treatments three. Twenty (77%) had stage IV disease; 22 (85%) had never achieved CR. Donor source was HLA matched sibling (n = 19, 73%), matched unrelated (n = 6, 23%) or syngeneic (n = 1). Conditioning therapy included total body irradiation in 23 patients and busulphan in three. Twenty-five received GVHD prophylaxis with cyclosporine A; + methotrexate (n = 19), + methylprednisolone (n = 2) or + T cell depletion of allograft +/- methotrexate (n = 4). Sixteen patients are alive, a median of 2.4 years post BMT. Death occurred due to transplant complications (n = 7) or underlying disease (n = 3). Eighteen (12 LGL, six CLL) of 22 evaluable patients (82%) achieved CR post BMT. Cumulative incidence of refractory/recurrent disease was 18% (95% confidence interval (CI) 7-42%). Overall and event-free survivals were 58% (95% CI 35-75%) and 54% (95% CI 32-72%), respectively. Allogeneic BMT for young patients with advanced LGL or CLL is feasible and can result in long-term disease-free survival.

Fludarabine and cladribine in relapsed/refractory low-grade non-Hodgkin's lymphoma: a phase II randomized study

BACKGROUND

It is unclear whether the purine analogs fludarabine (Flu) and cladribine (CdA) are non-resistant.

PATIENTS AND METHODS

Sixty patients with relapsed or refractory low-grade NHL were randomly allocated to initial treatment with either Flu 25 mg/m2, or CdA 0.14 mg/kg, each for five consecutive days every four weeks. Upon treatment failure, eligible patients were crossed over to the other study drug.

RESULTS

Overall response and CR were 68% and 48% with Flu, and 72% and 38% with CdA, respectively. For responders, actuarial three-year progression-free survival was 58% with Flu and 52% with CdA. Treatment with both drugs was well tolerated, with toxic effects primarily hematological. Two patients (8%) in the Flu group and 15 patients (47%, P = 0.001) in the CdA group were taken off study because of persistent hematological toxicity. After cross over, none of seven refractory patients responded, while eight of nine previously responsive patients achieved second responses.

CONCLUSIONS

Our study confirms that Flu and CdA have similar response rates and durations. However, further studies are required to optimize the CdA schedule and dosage in order to ameliorate its toxic profile while maintaining antitumor activity. The two drugs appear to be cross-resistant.

Cladribine with or without prednisone in the treatment of previously treated and untreated B-cell chronic lymphocytic leukaemia - updated results of the multicentre study of 378 patients

Between January 1992 and January 1999, we treated 378 B-chronic lymphocytic leukaemia (CLL) patients with cladribine (2-CdA), and 255 of the patients were also treated with prednisone. A total of 194 patients were previously untreated, and 184 had relapsed or refractory disease after previous other therapy. Complete response (CR) was obtained in 111 (29.4%) and partial response (PR) in 138 (36.5%) patients, giving an overall response (OR) rate of 65.9%. CR and OR were achieved more frequently in patients in whom 2-CdA was a first-line treatment (45.4% and 82.5% respectively) than in the pretreated group (12.5% and 48.4% respectively) (P < 0.0001). The median duration of OR for previously untreated patients was 14.7 months and for pretreated patients 13.5 months (P = 0.09). The median survival evaluated from the beginning of 2-CdA treatment was shorter in the pretreated group (16.3 months) than in the untreated group (19.4 months) (P < 0.0001). A total of 117 (63.9%) patients died in the pretreated group and 63 (32.6%) in the untreated group. In pretreated patients, 2-CdA + prednisone (P) and 2-CdA alone resulted in similar OR (51.0% and 45.0% respectively; P = 0.4). In contrast, in untreated patients, 2-CdA + P produced a higher OR (85.4%) than 2-CdA alone (72.1%) (P = 0.04). Infections and fever of unknown origin, observed in 91 (49.4%) pretreated and 74 (38.1%) untreated patients (P = 0.03), were the most frequent toxic effects. Our results indicate that 2-CdA is an effective, relatively well-tolerated drug, especially in previously untreated CLL.

Management of chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is the most common form of adult leukaemia in Western countries. The diagnosis requires mature-appearing lymphocytes in the peripheral blood to >5 x 10(9)/L. The immunophenotype typically includes B cell antigens CD19, CD20 and CD23, low expression of surface immunoglobulin and CD5+, with other T cell antigens absent. Bone marrow biopsy, although not required for diagnosis, must show at least 30% lymphocytes. Cytogenetic abnormalities are frequent in patients with CLL, and may be associated with poor prognosis. Clinically, most patients are asymptomatic at presentation, with incidental lymphadenopathy and/or hepatosplenomegaly in the routine physical examination. Infections by opportunistic pathogens are the major cause of death. Aggressive transformation occurs in 10% of patients with CLL, most commonly prolymphocytic leukaemia (PLL) and Richter's syndrome. PLL de novo must be differentiated from PLL of an aggressive transformation. The incidences of autoimmune diseases and solid or haemopoietic secondary malignancies are increased in patients with CLL. Clinical stage is the strongest prognostic factor in CLL. There is no indication for early intervention. The current recommendation to start treatment includes disease-related symptoms, massive and/or progressive hepatosplenomegaly or lymphadenopathy, increasing bone marrow failure, autoimmune disease, and recurrent infections. Alkylating agents (e.g. chlorambucil) and nucleoside analogues (e.g. fludarabine) are the most active agents for CLL. Fludarabine induces higher response rates, but no improvement in overall survival has been observed. Fludarabine is the drug of choice for the majority of patients with CLL. Chlorambucil may be helpful for elderly patients with poor performance, and for patients who do not tolerate fludarabine. No drug combination is better than single agents. For patients refractory to initial treatment, referral to a clinical trial is the best choice. Other salvage therapy includes retreatment with the same initial agent (chlorambucil or fludarabine) if initial response was observed, or fludarabine for patients refractory to chlorambucil. Promising new approaches include cycle-active agents, nelarabine, biological therapy such as anti-CD52 monoclonal antibody, bone marrow transplantation, including the use of submyeloablative preparative regimens ('minitransplant') to induce graft-versus-leukaemia effect, and gene therapy. Prophylactic antibacterials and intravenous immunoglobulin should not be used routinely during supportive care. Epoetin may be helpful for patients who have anaemia without obvious cause. Assessment of response to therapy in CLL has been updated by the National Cancer Institute Working Group, and these guidelines are used worldwide for clinical trials.

Waldenström's macroglobulinemia: clinical features, complications, and management

PURPOSE

To review the clinical features, complications, and treatment of Waldenström's macroglobulinemia, a low-grade lymphoproliferative disorder that produces monoclonal immunoglobulin (Ig) M.

METHODS

A review of published reports was facilitated by the use of a MEDLINE computer search and by manual search of the Index Medicus.

RESULTS

The clinical manifestations associated with Waldenström's macroglobulinemia can be classified according to those related to direct tumor infiltration, to the amount and specific properties of circulating IgM, and to the deposition of IgM in various tissues. Asymptomatic patients should be followed without treatment. For symptomatic patients, standard treatment consists primarily of oral chlorambucil; nucleoside analogs, such as fludarabine and cladribine, are effective in one third of previously treated patients and in up to 80% of previously untreated patients. Preliminary evidence suggests that anti-CD20 monoclonal antibody may be active in about 30% of previously treated patients and that high-dose therapy with autologous stem-cell rescue is effective in most patients, including some with resistance to nucleoside analogs.

CONCLUSION

Waldenström's macroglobulinemia has a wide clinical spectrum that practicing physicians need to recognize early to reach the correct diagnosis. When therapy is indicated, oral chlorambucil is the standard primary treatment, but cladribine or fludarabine can be used when a rapid cytoreduction is desirable. Prospective randomized trials are required to elucidate the impact of nucleoside analogs on patients' survival. A nucleoside analog is the treatment of choice for patients who have been previously treated with an alkylating agent.

Sequential cis-platinum and fludarabine with or without arabinosyl cytosine in patients failing prior fludarabine therapy for chronic lymphocytic leukemia: a phase II study

Patients with chronic lymphocytic leukemia (CLL) who fail fludarabine (Fluda) therapy have a poor response to subsequent salvage regimens and a poor prognosis. This study was undertaken to determine the efficacy and toxicity of a cis-platinum, (cis-p)fluda and arabinosyl cytosine (ara-C) combination in patients who were refractory to fluda or had relapsed following prior fluda therapy for CLL. Forty-one patients who had progressive CLL were treated on study. Eleven patients (27%) were sensitive to fluda and thirty (73%) refractory prior to study entry. Therapy consisted of cis-p 100 mg/m2 continuous intravenous (i.v.) infusion over 4 days, fluda 30 mg/m2 i.v. over 15 minutes on Days 3 and 4 either given alone (PF) or with ara-C 500 mg/m2 i.v. over 1 hour on Day 4 (PFA). The median number of PF or PFA courses received was two. No patient achieved a complete response. Eight patients (19%) achieved a partial response (PR), 28 were taken off study with progressive or refractory disease and 5 had induction deaths. The overall median survival was 6 months, 15 months in responding patients, and 4 months in non-responding patients. Rai stage I-II patients had a median survival of 7 months and stage III-IV patients had a median survival of 3 months. Major toxicities (myelosuppression, sepsis, renal failure and tumor lysis syndrome) were frequent. In conclusion, it can be said that the PF and PFA regimens have equivalent modest activity in patients with progressive CLL following prior fluda therapy, predominantly among patients whose disease was sensitive to fluda at last prior exposure. Ara-C did not add to the activity of the cis-p/fluda combination in this study group.

Evaluation of purine and pyrimidine analogues in human tumor cells from patients with low-grade lymphoproliferative disorders using the FMCA

The purine analogues fludarabine and cladribine (CdA) have recently become established to be effective treatment for low-grade non-Hodgkin's lymphoma (NHL). The pyrimidine nucleoside analogue cytarabine (AraC) has an important place in the treatment of acute leukemia, and gemcitabine is a new pyrimidin antimetabolite which has shown clinical activity against solid tumors. We have used the semiautomated fluorometric microculture cytotoxicity assay (FMCA), based on the measurement of fluorescence generated from cellular hydrolysis of fluorescein diacetate (FDA), to study these drugs. Eighty samples from 60 patients with low-grade NHL were studied. Fifty samples from patients with acute lymphoid leukemia (ALL) and 118 samples from patients with acute myeloid leukemia (AML) were included for comparison. The results indicate that the purine- and pyrimidine nucleoside analogues tested may be as active against low-grade NHL as against acute leukemia. In low-grade NHL, AraC seems to be even more active in comparison to CdA (p=<0.0001) and fludarabine (p=0.001). Untreated patients were more drug sensitive than previously treated patients. Gemcitabine showed the highest correlation with AraC (0.90) whereas CdA showed the highest correlation with fludarabine (0.84). Based on these results we propose that AraC and gemcitabine may have a role in the treatment of low-grade NHL.

Cladribine with cyclophosphamide and prednisone in the management of low-grade lymphoproliferative malignancies

The feasibility of combining cladribine with cyclophosphamide and prednisone in the management of indolent lymphoid malignancies was determined. Nineteen patients [nine chronic lymphocytic leukaemia (CLL), seven non-Hodgkin's lymphoma (NHL) and three macroglobulinaemia (M))] received cladribine 0.1 mg kg(-1) per day as a subcutaneous bolus injection on days 1-3 (up to 5 injections) with intravenous cyclophosphamide 500 mg m(-2) on day 1 and oral prednisone 40 mg (m-2) on days 1-5 at 4-weekly intervals up to a maximum of six courses. A total of 80 courses were given. Overall response rate was 88%, with four patients achieving a complete clinical and haematological response and 12 achieving a partial response. Neutropenia WHO grade 4 in two patients and WHO grade 3 infection in one patient were the limiting toxicities on treatment. During the follow-up, WHO grade >3 haematological complications occurred in five patients and WHO grade >3 non-haematological complications in five patients. There were no treatment-related deaths. This study demonstrates the feasibility of the cladribine/cyclophosphamide/prednisone (CCP) combination that appears highly active and safe in the management of indolent lymphoid malignancies.

Expression of Apoptosis-Regulating Proteins in Chronic Lymphocytic Leukemia: Correlations With In Vitro and In Vivo Chemoresponses

B-cell chronic lymphocytic leukemia (B-CLL) represents a neoplastic disorder caused primarily by defective programmed cell death (PCD), as opposed to increased cell proliferation. Defects in the PCD pathway also contribute to chemoresistance. The expression of several apoptosis-regulating proteins, including the Bcl-2 family proteins Bcl-2, Bcl-XL, Mcl-1, Bax, Bak, and BAD; the Bcl-2–binding protein BAG-1; and the cell death protease Caspase-3 (CPP32), was evaluated by immunoblotting using 58 peripheral blood B-CLL specimens from previously untreated patients. Expression of Bcl-2, Mcl-1, BAG-1, Bax, Bak, and Caspase-3 was commonly found in circulating B-CLL cells, whereas the Bcl-XL and BAD proteins were not present. Higher levels of the anti-apoptotic protein Mcl-1 were strongly correlated with failure to achieve complete remission (CR) after single-agent therapy (fludarabine or chlorambucil) (P = .001), but the presence of only seven CRs among the 42 patients for whom follow-up data were available necessitates cautious interpretation of these observations. Higher levels of the anti-apoptotic protein BAG-1 were also marginally associated with failure to achieve CR (P = .04). Apoptosis-regulating proteins were not associated with patient age, sex, Rai stage, platelet count, hemoglobin (Hb) concentration, or lymph node involvement, although higher levels of Bcl-2 and a high Bcl-2:Bax ratio were correlated with high numbers (>105/μL) of white blood cells (WBC) (P = .01; .007) and higher levels of Bak were weakly associated with loss of allelic heterozygosity at 13q14 (P = .04). On the basis of measurements of apoptosis induction by fludarabine using cultured B-CLL specimens, in vitro chemosensitivity data failed to correlate with in vivo clinical response rates (n = 42) and expression of the various apoptosis-regulating proteins. Although larger prospective studies are required before firm conclusions can be reached, these studies show the expression in B-CLLs of multiple apoptosis-regulating proteins and suggest that the relative levels of some of these, such as Mcl-1, may provide information about in vivo responses to chemotherapy. In vitro chemosensitivity data, however, do not appear to be particularly useful in predicting responses in B-CLL.

Expression of Apoptosis-Regulating Proteins in Chronic Lymphocytic Leukemia: Correlations With In Vitro and In Vivo Chemoresponses

B-cell chronic lymphocytic leukemia (B-CLL) represents a neoplastic disorder caused primarily by defective programmed cell death (PCD), as opposed to increased cell proliferation. Defects in the PCD pathway also contribute to chemoresistance. The expression of several apoptosis-regulating proteins, including the Bcl-2 family proteins Bcl-2, Bcl-XL, Mcl-1, Bax, Bak, and BAD; the Bcl-2–binding protein BAG-1; and the cell death protease Caspase-3 (CPP32), was evaluated by immunoblotting using 58 peripheral blood B-CLL specimens from previously untreated patients. Expression of Bcl-2, Mcl-1, BAG-1, Bax, Bak, and Caspase-3 was commonly found in circulating B-CLL cells, whereas the Bcl-XL and BAD proteins were not present. Higher levels of the anti-apoptotic protein Mcl-1 were strongly correlated with failure to achieve complete remission (CR) after single-agent therapy (fludarabine or chlorambucil) (P = .001), but the presence of only seven CRs among the 42 patients for whom follow-up data were available necessitates cautious interpretation of these observations. Higher levels of the anti-apoptotic protein BAG-1 were also marginally associated with failure to achieve CR (P = .04). Apoptosis-regulating proteins were not associated with patient age, sex, Rai stage, platelet count, hemoglobin (Hb) concentration, or lymph node involvement, although higher levels of Bcl-2 and a high Bcl-2:Bax ratio were correlated with high numbers (>105/μL) of white blood cells (WBC) (P = .01; .007) and higher levels of Bak were weakly associated with loss of allelic heterozygosity at 13q14 (P = .04). On the basis of measurements of apoptosis induction by fludarabine using cultured B-CLL specimens, in vitro chemosensitivity data failed to correlate with in vivo clinical response rates (n = 42) and expression of the various apoptosis-regulating proteins. Although larger prospective studies are required before firm conclusions can be reached, these studies show the expression in B-CLLs of multiple apoptosis-regulating proteins and suggest that the relative levels of some of these, such as Mcl-1, may provide information about in vivo responses to chemotherapy. In vitro chemosensitivity data, however, do not appear to be particularly useful in predicting responses in B-CLL.

2-Chloro-2'-deoxyadenosine, an antileukemic drug, has an early effect on cellular mitochondrial function

2-Chloro-2'-deoxyadenosine [CldAdo (cladribine)], a novel effective antileukemic agent, was examined for its effects on cellular mitochondrial function and DNA content after long term (< or = 7-day) incubation of cultured CCRF-CEM human leukemia cells. Dideoxycytidine (ddC), which is known to have a delayed effect on mitochondrial DNA content, was used as a positive control to monitor mitochondrial dysfunction. CldAdo at 6-16 nM was toxic to cells within 24 hr, which is in contrast to 300 nM ddC, which had no effect on cell growth for the first 4 days of treatment. Cellular lactic acid production was used to monitor concomitant perturbations in oxidative phosphorylation during drug treatment. Unlike the delayed increase in lactate observed with ddC exposure, CldAdo-treated cells exhibited a 2-2.4-fold increase in lactate levels after 2 days of exposure to 16 nM CldAdo. By days 4 and 7, however, lactate production returned to control levels. Shorter incubations with CldAdo revealed that lactate levels began to increase within 12 hr of drug exposure, paralleling cytotoxicity. We also examined mitochondrial DNA content during drug treatment by competitive polymerase chain reaction. ddC (300 nM) reduced mitochondrial DNA levels from approximately 1000 copies/untreated cell to approximately 130 copies/cell after 7 days of exposure. In contrast, cytotoxic doses of CldAdo had little or no effect on mitochondrial DNA content during the 1-week incubation. Thus, the early CldAdo-induced perturbation of mitochondrial function was not associated with a loss of mitochondrial DNA per cell. In addition, no evidence of DNA laddering, indicative of cellular apoptosis, was detected at these dosage levels and treatment times.

2-Chlorodeoxyadenosine in the treatment of relapsed/refractory chronic lymphoproliferative disorders

2-Chlorodeoxyadenosine (2-CdA) is a purine analog with cytotoxic activity on both resting and cycling lymphocytes which has been used as salvage therapy in advanced/resistant chronic lymphoproliferative disorders. In our study 39 patients (19 B-CLL, 5 B-PLL, 9 low-grade B-NHL, 5 CTCL and 1 high-grade T-NHL) who relapsed or became resistant after 1-4 chemotherapy regimens were treated with 2-CdA 6 mg/m2 per day by 2 h infusion for 5 d every 28 d. The overall clinical response rate, including complete remission (CR) and partial remission (PR), was 66%. Two of 19 (10%) B-CLL patients achieved a CR lasting 9 months, while 11/19 B-CLL (58%) and 4/5 B-PLL (3 B-PLL/B-CLL and 1 B-PLL) (80%) achieved a PR. Interestingly, 5 of 6 patients who had been previously treated with fludarabine obtained a clinical response (2 CR and 3 PR). One of 9 (11%) low-grade B-NHL patients achieved a CR and relapsed after 26 months, and 5/9 (55%) achieved a PR. One of 5 (20%) CTCL achieved a CR lasting 32 months, while 2/5 (40%) achieved a PR. The overall mean duration of PR was 7.4 months and no differences were observed among different groups of patients. Toxicity was acceptable, as only a transient severe hematological impairment was observed in 20% of the patients while nonhematological toxicity was not documented. Two patients died because of bacterial pneumonia, 1 of meningitis due to Listeria and 9 from progression of the disease. In conclusion, treatment with 2-CdA in heavily pretreated patients with chronic lymphoproliferative disorders is well tolerated and obtains high response rates, even in patients relapsed after treatment with fludarabine.

The COP regimen is not a feasible treatment for advanced, refractory chronic lymphocytic leukemia

The COP regimen has been widely used as a second-line treatment for advanced chronic lymphocytic leukemia (CLL). In this retrospective analysis of COP therapy 24 patients with CLL were included. All but two patients had previously been treated with alkylating agents and had become refractory to the therapy. The overall response rate to COP was 25%. Three patients had CR (12.5%), three PR (12.5%), five SD (21%), four PD (17%), and nine patients died (37.5%) during the COP treatments. The cause of death was neutropenic sepsis in all cases. The median duration of responses was 18 months. The median survival of all patients was 9.5 months. The survival of responders was 24.5 and of non-responders only 5.5 months. The COP regimen seems to have low efficacy in the treatment of refractory CLL and the toxicity of this regimen in the late disease phase appears to be unacceptable.

2-chloro-2'-deoxyadenosine: clinical applications in hematology

The anticancer drug 2-chloro-2'-deoxyadenosine (CdA) belongs to the family of purine nucleoside analogs. CdA is exquisitely cytotoxic both to the dividing and to the non-dividing lymphocyte, which supports its use in lymphoproliferative disorders of low-grade malignancy. Indeed, the best clinical results with CdA are achieved in hairy-cell leukemia, in chronic lymphocytic leukemia, in Waldenström's macroglobulinemia and in low-grade malignant lymphoma. Most patients with hairy-cell leukemia achieve a complete response with a single course of CdA. However, the disease is not eradicated and a fraction of complete responders will eventually relapse. In chronic lymphocytic leukemia and in malignant lymphoma, complete or partial responses can be achieved in approximately 40% of previously treated patients, even after classical chemotherapy has failed. However, few responses sustain beyond 1 to 2 years, while longer unmaintained responses may be obtained in Waldenström's macroglobulinemia. More responses (70-80%) are achieved in patients with chronic lymphoproliferative disorders treated de novo with CdA but their impact on survival remains to be established. More than 10 years after its first use in clinical practice, late adverse consequences of the severe and sustained immunosuppression induced by CdA have not been reported but should still be closely monitored.

Infectious complications after 2-chlorodeoxyadenosine therapy

Infection is a common adverse event after therapy with nucleoside analogs, including 2-chlorodeoxyadenosine (CdA). However, the incidence of CdA-related infections has been poorly documented. In this study we compare, in the same patient population, the incidence of infectious episodes during the 6-month period before CdA to their incidence during the 6 months after initiating therapy. Ninety-five patients with hematological malignancies were studied. The incidence of infectious episodes almost doubled after CdA (0.87 vs. 0.47 during the pre-CdA period). The following factors were associated with an increased risk of infection after therapy: a history of previous chemotherapy, infection during the pre-CdA period and a diagnosis of chronic lymphocytic leukemia or of non-Hodgkin's lymphoma. Age, neutrophil and lymphocyte count at onset of CdA and time interval between diagnosis and therapy with CdA did not correlate with the infectious risk. The pattern of infections was modified after therapy with an increase of herpes virus infections ( 1 vs. 8 episodes, p=0.04) and of fever of unknown origin (6 vs. 17 episodes, p=0.03). In conclusion, a population at high risk for developing infectious complications after CdA therapy can be identified. Specific measures aimed at reducing the incidence of infectious events should concentrate on this population.

Long-term survival following cladribine (2-chlorodeoxyadenosine) therapy in previously treated patients with chronic lymphocytic leukemia

PURPOSE

To assess long-term survival following cladribine salvage treatment for previously treated patients with chronic lymphocytic leukemia.

PATIENTS AND METHODS

Fifty-two patients aged 39-84 years with previously treated CLL received cladribine 0.12 mg/kg/day in 2-hour infusions for 5 days in monthly courses. Two-thirds were refractory to previous therapy, and 8 had prior fludarabine.

RESULTS

Sixteen (31%) patients achieved complete response (CR) and 14 (27%) partial remission (PR) according to consensus criteria. Response correlated with clinical stage, number of previous treatment regimes, blood lymphocyte count, and lymphocyte halflife following the first cladribine course. Toxicity included pneumonia (n = 9), herpes zoster (n = 7), and septicemia (n = 2). Four patients in CR underwent high-dose chemotherapy with autologous blood stem cell support, and 2 remain in CR 48 and 60 months from start of cladribine, and 2 had relapse at 42 and 48 months, respectively. Median progression-free survival (Kaplan-Meier analysis) for CR patients was 23 months from start of cladribine treatment, and for PR patients 16 months. The projected overall survival was 80% at 3 years for CR patients, and the median survival 28 months for PR patients and 4 months for non-responding patients.

CONCLUSIONS

Our previous finding of durable CRs from cladribine in advanced CLL is thus confirmed in a larger patient material, and follow-up indicate that long-term survival may be achieved.

Purine analogs in chronic lymphocytic leukemia and Waldenström's macroglobulinemia

The observation of lymphopenia in children deficient in adenosine deaminase (ADA) led to exploration of an inhibitor of the enzyme in lymphoid malignancies; thus deoxycoformycin was the first purine nucleotide used in human trials. Fludarabine and 2-chlorodeoxyadenosine (2-CdA), agents resistant to deamination by ADA, have been utilized in the past decade. All of these drugs act as competitors for deoxyadenosine triphosphate at the A sites of the elongating DNA strand, terminating DNA synthesis. However, their remarkable efficacy in indolent lymphoid malignancies is not well explained by this mechanism of action. The induction of apoptosis and resultant cytotoxicity may be important in their activity. As a single agent, fludarabine has been associated with overall remission rates as high as 55% in previously treated patients and 79% in previously untreated patients. With this agent, a dosage regimen of 25-30 mg/m2 daily over 5 days seems to be the most effective to date. Fludarabine has shown more favorable remission rates than the traditional salvage regimens incorporating anthracyclines and alkylating agents. Regimens combining fludarabine with mitoxantrone and with doxorubicin have shown minimal therapeutic advantage in CLL, while combination with cyclophosphamide appears promising. Remission rates with deoxycoformycin have been lower than with fludarabine, but studies have been small in patient numbers. The agent 2-CdA, first successful in hairy-cell leukemia, has shown overall response rates in chronic lymphocytic leukemia similar to those seen with fludarabine. Whether or not cross-resistance occurs among the purine analogs has not been fully determined, but occasional patients with disease refractory to fludarabine have responded to 2-CdA. Cumulative myelosuppression and immunosuppression may be experienced however. In the B-cell neoplastic entity, Waldenström's macroglobulinemia, fludarabine therapy in patients previously treated with alkylating agents and/or steroids produced a 36% response rate. Only two previously untreated patients received fludarabine, and both responded. A similar response rate of 40% was seen when 2-CdA was administered to previously treated patients. This response rate increased to 85% in a study of 26 previously untreated patients, making this one of the most effective drugs yet investigated in this condition.

Purine analogues in the management of lymphoproliferative diseases

Three analogues of the purine 2-deoxyadenosine are available for the treatment of low grade lymphoproliferative disorders: pentostatin, cladribine and fludarabine. They have some common features in their mode of action, but differ both in their detailed pharmacology and the extent to which they have activity against specific lymphoid malignancies. Studies defining the scope of these drugs as single agents are now being followed by plans to exploit their potential synergy with other agents and clinically to define useful combination therapies.

Opportunistic pulmonary infections with fludarabine in previously treated patients with low-grade lymphoid malignancies: a role for Pneumocystis carinii pneumonia prophylaxis

The high incidence of opportunistic pulmonary infections in fludarabine-treated patients at Walter Reed Army Medical Center (WRAMC) and in the literature are described. A CancerLit search of fludarabine from June 1983-April 1994 with subsequent cross referencing and a retrospective review of all patients receiving fludarabine at WRAMC was performed. A total of 2,269 patients with low-grade lymphoid malignancies who received 7,547 + cycles of fludarabine were identified from the literature. Seventy-three (3.2%) of these patients developed opportunistic infections. Seventy-one (97%) of these infections occurred in patients who were pretreated with alkylator regimens or corticosteroids. Forty-five (2%) of these were of respiratory origin and associated with a 56% mortality rate. In contrast, 6 of the 21 patients (29%) treated with fludarabine at WRAMC developed opportunistic pulmonary infections which included three Pneumocystis carinii (PCP), one PCP/disseminated Candidiasis, one Mycobacterium avium intracellulare, and one Aspergillus niger pneumonia. These infections developed during and after treatment with fludarabine in alkylator-resistant patients who had received corticosteroids before (n = 6), during (n = 1), or after (n = 4) fludarabine therapy. Lack of PCP prophylaxis was the only significant (P = .018) variable that differentiated patients who developed opportunistic pulmonary infections. Corticosteroid treatment before, during, or after fludarabine treatment in patients with alkylator-resistant, low-grade lymphoid malignancies who have not received PCP prophylaxis is associated with an increased risk of opportunistic pulmonary infections. Aggressive work-up of pulmonary syndromes and PCP prophylaxis in these patients should be considered during and after treatment with fludarabine.

Purine analogs in the treatment of low-grade lymphomas and chronic lymphocytic leukemias

The purine analogs fludarabine (FAMP), 2-chlorodeoxy-adenosine (2-CDA) and 2-deoxycoformycin (DCF) comprise a novel group of agents with high activity in low-grade lymphoid malignancies. Although all three agents share several mechanisms of action, such as the induction of apoptosis, and toxic effects, such as prolonged immunosuppression, their activity appears to be different in different disorders. While FAMP and possibly also 2-CDA are highly active in chronic lymphocytic leukemia and low-grade follicular lymphomas, 2-CDA and DCF are most effective in hairy cell leukemia. However, prospective comparative evaluations are in progress and their results may ultimately help to define the appropriate indications for and potential side effects of these highly promising new agents.