Treatment of chronic lymphocytic leukemia in early and stable phase of the disease: long-term results of a randomized trial

Relationship between progression-free survival and overall survival in chronic lymphocytic leukemia: a literature-based analysis

BACKGROUND

The endpoints of progression-free survival (pfs) and time-to-progression (ttp) are frequently used to evaluate the clinical benefit of anticancer drugs. However, the surrogacy of those endpoints for overall survival (os) is not validated in all cancer settings. In the present study, we used a trial-based approach to assess the relationship between median pfs or ttp and median os in chronic lymphocytic leukemia (cll).

METHODS

The pico (population, interventions, comparators, outcomes) method was used to conduct a systematic review of the literature. The population consisted of patients with cll; the interventions and comparators were standard therapies for cll; and the outcomes were median pfs, ttp, and os. Two independent reviewers screened titles, abstracts, and full papers for eligibility and then extracted data from selected studies. Correlation coefficients were calculated to assess the relationship between median pfs or ttp and median os. Subgroup correlation analyses were also conducted according to the characteristics of the selected studies (such as line of treatment and type of treatment under investigation).

RESULTS

Of the 1263 potentially relevant articles identified during the literature search, twenty-three were included. On average, median pfs or ttp was 16.0 months (standard deviation: 12.4 months) and median os was 43.5 months (standard deviation: 31.2 months). Results of the correlation analysis indicated that median pfs or ttp is highly correlated with median os (Spearman correlation coefficient: 0.813; p ≤ 0.001). A significant correlation between median pfs or ttp and median os was observed in second- and subsequent-line therapies, but not in the first-line setting.

CONCLUSIONS

Our study demonstrates a strong correlation between median pfs or ttp and median os in previously treated cll, which reinforce the hypothesis that pfs and ttp could be adequate surrogate endpoints for os in this cancer setting.

Economic assessment on the management of chronic lymphocytic leukaemia

In the last decade, several new promising treatments for chronic lymphocytic leukaemia (CLL) have been developed. Healthcare costs are increasing and new treatments tend to be very expensive; therefore, information about the cost effectiveness in treatments for CLL is urgently needed. The authors performed a literature review on the currently available economic evaluations on CLL treatments. A total of 65 articles were found, of which 11 could be included. These articles were evaluated on the basis of six methodological requirements for economic evaluations, enabling readers to judge the value of the studies. Only a small amount of information was available on the costs of CLL treatments. Future economic evaluations should be performed according to the methodological requirements for these studies, which should also be properly documented.

New directions in the diagnosis and treatment of chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is the most common leukaemia of adults in Western countries. It is a systemic haematological malignancy that originates from B cells (B-CLL) in 95% of patients, while only a minority are derived through malignant transformation of T cells (T-CLL). Although B-CLL is classified as a non-Hodgkin's lymphoma, several issues make this leukaemia a unique entity among malignant lymphoma. Inhibition of the programmed cell death (apoptosis) and upregulation of the anti-apoptotic protein Bcl-2 are key elements of the pathophysiology of B-CLL cells and define clinical prognosis. Furthermore, B-CLL cells are arrested in G0/G1 phase of the cell cycle. Dysfunctional apoptosis and cell cycle are the main reasons for the clinical enigma, that CLL can not yet be cured with conventional chemotherapy. However, the molecular pathways that are responsible for this characteristic feature of the B-CLL cells still need further definition.Recently, considerable progress has been made in defining the molecular basis for the pathogenesis of CLL and in finding new therapeutic options. Recent studies indicate that B-CLL cells may be delineated from two main groups of normal B cells, i.e. pre- and postgerminal B cells, and can be distinguished through lack of or existence of mutations of the V heavy chain gene. This differential mutational status of the Ig V gene has significant impact on patient survival. Modern cytogenetic methods such as fluorescence in situ hybridisation (FISH) have opened a new era in the molecular analysis of CLL cells. Determining the chromosomal aberration of the leukaemic cells has become a standard scientific programme for each clinical trial. The cytogenetic profile may soon help to define a clinical risk profile and guide the various treatment strategies. Further progress has been made in the therapy of CLL. Purine analogues such as fludarabine were able to induce significant improvement in remission rates; however, they did not lead to improved survival. Chimera of murine or rat monoclonal antibodies and human antibodies were designed to treat CLL. Antibodies such as rituximab and alemtuzumab (Campath-1H), directed against CD20 and CD52, respectively, appear as attractive alternatives to conventional chemotherapy because of their lack of significant myelotoxicity. Studies using myeloablative chemotherapy followed by autologous or allogeneic stem cell transplantation were initiated with the hope of finding a cure for CLL. In contrast to autologous stem cell transplantation, allogeneic transplants appear to display a plateau of relapse rates. In conclusion, for many years CLL was considered as a chronic haematological malignancy that required only few diagnostic tools and for whom no hope of cure could be offered. The current review focuses on recent improvements in diagnosis and treatment of CLL that have opened a new era in the management of patients with this systemic malignancy.

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.

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.

Does intensive treatment with high dose chlorambucil and prednisone as first line and cladribine as second line influence the survival of the patients with chronic lymphocytic leukemia?

Cladribine (2-CdA) and fludarabine are the new purine analogs introduced in the treatment of chronic lymphocytic leukemia (CLL). Despite the high response rate, their influence on survival is still uncertain. The aim of this study was a retrospective analysis and comparison of the response rate and survival of CLL patients treated with high dose chlorambucil (HDChl) as first and 2-CdA as second line, with an historical group of patients never treated with purine analogs who received standard doses of chlorambucil (SDChl). We analyzed 347 patients with CLL treated between January 1985 and January 2000. Group A (190 patients) received HDChl (12 mg/m(2) ) with prednisone (P) 30 mg/m(2) daily for 7 days monthly as first line and in refractory or early relapsed patients 2-CdA (0.12 mg/kg/day) for 5 days with or without P (30mg/m(2) ) as second line. Group B (157 patients) received continuous SDChl (4-8 mg/m(2) /day) and P as first line and COP or CHOP as second line. The overall response rate (OR) for the first line was 48,4% in group A and 38,9% in group B (p=0.09). 148 patients in group A and 52 in group B received the second line treatment and the second OR was 19.6% and 13.5%, respectively (p=0.4). At the time of analysis, 124 patients died in group A and 139 in group B. Median survival was 65 months and 50 months, respectively. In group A, survival was longer in advanced Rai stage patients (p=0.001) but in early Rai stage was similar for both groups (p=0.4). We suggest that intensive treatment with HDChl as first line and 2-CdA as second line should be applied in more advanced rather than in less advanced stages of CLL until the final results of randomized clinical trials are available.

In vitro improvement of chlorambucil-induced cytotoxicity by deflazacort and 6-methylprednisolone in B-cell chronic lymphocytic leukaemia

We examined whether CLL cell chemosensitivity to in vitro exposure to chlorambucil (CLB) might be improved by the presence of deflazacort (DFZ) in comparison to 6-methylprednisolone (PDN). The PDN lethal dose (LD)50 values were low in 5 samples, intermediate in 4 and high in 7. Low, intermediate and high DFZ-LD50 values were detected in 3, 2 and 11 samples, respectively. The CBL-LD50 mean values were significantly reduced at all PDN and at the 4 highest DFZ concentrations. However, a dose-response effect was seen only in the DFZ group. Both CLB-DFZ and CLB-PDN interactions were analysed in 16 samples at 25 different dose-combinations, resulting in 400 comparisons between expected and observed leukaemic cell survival (LCS) values for each group. In particular, 45.75% and 40% dose combinations were synergistic in CLB-DFZ and CLB-PDN groups, respectively. A relatively higher number of antagonistic interactions were observed among CLB-PDN dose combinations, while analogous number of additive interactions were detected. At concentrations of CLB x1 microgram/ml the phenomenon of synergism, regardless of the steroid concentration, did occur more frequently. On the other hand, a more elevated number of antagonistic interactions were counted at CLB 100 micrograms/ ml. In conclusion, both DFZ and PDN synergize in vitro with CLB, especially at low concentrations of the alkylating agent.

The bone-marrow infiltration pattern in B-cell chronic lymphocytic leukemia is not an important prognostic factor. Danish CLL Study Group

In a multicentre study of 635 consecutive newly diagnosed patients with B-CLL, the histological bone marrow (BM) specimens were reviewed independently by each of 3 pathologists and found evaluable for BM infiltration pattern in 575 patients, 404 of whom had a CD5+, mainly FMC7-, faint surface-membrane immunoglobulin (SIg) fluorescence-intensity ppenotype. In these 404 patients the following BM infiltration patterns were found: mixed nodular-interstitial (30%), moderate interstitial (44%), heavy interstitial (20%) and diffuse packed (6%). In univariate survival analysis, significant differences were found according to BM pattern (p < 0.05), the presence of nodules being a favorable prognostic sign. In multivariate survival analysis in a model including age, clinical stage, BM pattern, BM lymphocytosis, WBC and sex, only age and stage but not BM pattern or BM lymphocytosis had independent prognostic significance. In stage A, progression-free survival was significantly longer in patients with nodular than in patients with non-nodular bone-marrow pattern. The overall survival of these patients, however, did not differ, possibly owing to the prompt and prolonged treatment given to most patients at the time of progression to stage B or C. We conclude that in CD5+, SIg(faint), mainly FMC7-B-CLL, bone-marrow histology may predict unstable disease in early clinical stage but is not important for treatment decisions, when these are based on clinical stage.