Long-term clinical outcome of B-cell chronic lymphocytic leukaemia patients in clinical remission phase evaluated at phenotypic level

Chronic lymphocytic leukemia in India-A clinico-hematological profile

Chronic lymphocytic leukemia (CLL) is the most common form of leukemia in elderly people. The clinico-hematological profile and treatment outcome of patients with CLL were assessed using retrospective case record analysis over 11 years. There were 95 (75 males: 20 females) patients with a median age of 61 years. Thirty patients were aged 55 years or less (young CLL patients) and 65 were more than 55 years of age (elder CLL patients). Sixty percent patients had non-specific complaints, such as weakness, cough and indigestion. Twenty-six (27%) patients had pallor and 24 (25%) had fever as initial presenting manifestation. Bleeding manifestations were seen in 7 patients. Seven patients were diagnosed incidentally. Lymphadenopathy, splenomegaly and hepatomegaly were seen in 52 (55%), 63 (66%) and 60 (63%) patients, respectively. The median white blood cell count and absolute lymphocyte counts were 70,600 and 51,490/mul, respectively. Three patients had autoimmune hemolytic anemia. Twenty-five patients (26%) had anemia with hemoglobin < 11 g/dl and thrombocytopenia with platelet count 100 x 10(3)/mm(3) was seen in 17 (18%). Interstitial nodular, mixed and diffuse bone marrow (BM) involvement was seen in 10.2, 67.3, 6.1 and 16.3% cases, respectively. Eighteen (60%) young patients and 35 (54%) older patients required treatment with chlorambucil. The mean time from initial diagnosis to treatment was 4.6 +/- 10.7 months. None of our patient attained complete response. Six patients obtained partial response. Median duration of chlorambucil was 7 months (1-86 months). Forty-six patients had stable disease. Three patients died. Median survival of study group was 4 years (8 months-13 years). In older CLL it was 4 years (8 months-11 years) and in young patients, survival duration was 5.5 years (1-13 years).

Use of alemtuzumab and rituximab consolidation in CLL: Pros and cons

As new therapeutic approaches have improved responses and outcomes in the treatment of chronic lymphocytic leukemia (CLL), the scientific community focuses now on diagnostic procedures and definitions of response in CLL. The use of monoclonal antibodies in particular has made it possible to treat CLL more effectively. The success of these new therapeutic tools can be traced back to the eradication of detectable disease in a significant number of patients. Therefore, the evaluation of minimal residual disease has become an important end point within clinical trials. This article describes various methods of assessing minimal residual disease and presents data demonstrating that new therapeutic approaches can eliminate residual malignant cells at the highest levels of sensitivity currently available. Although initial evidence suggests that the use of alemtuzumab induces a survival benefit when used in the consolidation setting, important safety issues remain to be resolved before this approach can be introduced in routine practice.

Comparison of cladribine plus cyclophosphamide with fludarabine plus cyclophosphamide as first-line therapy for chronic lymphocytic leukemia: a phase III randomized study by the Polish Adult Leukemia Group (PALG-CLL3 Study)

PURPOSE Little is known about comparison of the activity of different purine nucleoside analogs in chronic lymphocytic leukemia (CLL). We conducted a randomized phase III trial to compare efficacy and safety of cladribine and fludarabine, each combined with cyclophosphamide, in previously untreated progressive CLL. PATIENTS AND METHODS Patients received cladribine at 0.12 mg/kg combined with cyclophosphamide at 250 mg/m(2) for 3 days intravenously (CC regimen) or fludarabine at 25 mg/m(2) combined with cyclophosphamide at 250 mg/m(2) for 3 days intravenously (FC regimen), every 28 days for up to six cycles. The primary end point was complete response (CR) rate. Secondary end points included overall response rate (ORR), progression-free survival (PFS), overall survival (OS), and treatment-related toxicity. RESULTS Of 423 randomly assigned patients (211 to CC and 212 to FC), 395 were evaluated in the final analysis. The CR and ORR reached 47% and 88% in the CC arm and 46% and 82% in the FC arm (P = .25 and P = .11, respectively). The median PFS was 2.34 years with CC and 2.27 years with FC (P = .51). OS and grade 3/4 treatment-related toxicity were also comparable. Moreover, we did not observe any significant differences in CC and FC efficacy across different patient prognostic subgroups that included patients with 17p13 (TP53 gene) deletion who had poor survival in both study arms. CONCLUSION Cladribine and fludarabine in combination with cyclophosphamide are equally effective and safe first-line regimens for progressive CLL. Both combinations have unsatisfactory activity in patients with 17p13 (TP53 gene) deletion.

Eradication of Minimal Residual Disease with Alemtuzumab in B-Cell Chronic Lymphocytic Leukemia (B-CLL) Patients: The Need for a Standard Method of Detection and the Potential Impact of Bone Marrow Clearance on Disease Outcome

The introduction of new therapeutic agents, such as fludarabine phosphate (Fludara) and alemtuzumab (MabCampath, Campath), has made it possible to treat B-cell chronic lymphocytic leukemia (B-CLL) more effectively, compared with alkylating agents. However, although an increasing number of patients are able to achieve complete remission (CR), relapse is almost inevitable, because of the re-emergence of the malignant clone from small numbers of residual malignant cells. This phenomenon has introduced a need for a more sensitive assessment of low-level disease which, in turn, has encouraged the development of therapies aimed at the eradication of all residual disease in CR patients. The eradication of residual disease is associated with improved remission durability and has great potential in offering the possibility of cure. Alemtuzumab is the foundation of many eradication-based treatment approaches because of its ability to achieve clinical remissions and to successfully purge minimal residual disease (MRD) from both blood and bone marrow in B-CLL patients. This article describes and compares polymerase chain reaction (PCR) and flow cytometric methodologies for the assessment of MRD, and presents data demonstrating that alemtuzumab can eliminate residual malignant cells from blood and bone marrow (whether assessed by PCR or flow cytometry) at the highest levels of sensitivity currently available. The ability to clear MRD from bone marrow in patients achieving clinical CR using alemtuzumab is a significant step forward in the treatment of B-CLL, and supports treatment strategies in which alemtuzumab is used in combination with other agents. Purging of MRD from both blood and bone marrow also enables patients to proceed to autologous hematopoietic stem cell transplantation, a strategy that is able to achieve long-term remission.

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.

Re-treatment with cladribine-based regimens in relapsed patients with B-cell chronic lymphocytic leukemia. Efficacy and toxicity in comparison with previous treatment

The aim of the study was to determine the effectiveness and toxicity of cladribine (2-CdA) used alone or in combination with prednisone (P) or cyclophosphamide and mitoxantrone in re-treatment of patients with progressive B-cell chronic lymphocytic leukemia (B-CLL). We analyzed treatment outcome in 40 patients who had responded to previous treatment with 2-CdA-based regimens. Criteria for re-treatment were the same as for the first treatment. The patients were retreated with the same agents if they responded to the first treatment and then relapsed with progressive disease not earlier than 3 months after achieving the first response. Eight patients received 2-CdA alone (0.12 mg kg(-1) d(-1)) i.v. for 5 d, and 21 patients additionally were given P (30 mg m(-2) d(-1)) orally, also for 5 d. Eleven patients received 2-CdA for 3 d combined with cyclophosphamide (650 mg m(-2)) i.v. and mitoxantrone (10 mg m(-2)) i.v. on day 1 (CMC regimen). The cycles were repeated usually at 4 wk intervals or longer if severe myelosuppression or infections occurred. The therapy was finished if complete remission (CR) was achieved or until maximum of six courses. Overall response (OR) in re-treatment was obtained in 16 out of 40 (40%) patients (95% CI 16-64), including 62% after 2-CdA, 33% after 2-CdA +P and 36% after CMC. CR was obtained in four (10%) patients. Residual disease evaluated in the patients with CR by surface immunophenotyping had been demonstrated in 5 out of 16 (31%) patients after the first treatment and in one out of four (25%) patients after re-treatment. The median progression-free survival (PFS) was 16 months (range 3-39) for the first treatment and 9.5 months (range 3-18) for re-treatment (P=0.34). Grade III or IV neutropenia was observed in 20% patients during the first treatment and in 35% patients during re-treatment (P=0.1). 2-CdA-induced thrombocytopenia occurred in 20% and 42% of the patients, respectively (P=0.05). Anemia was also more frequent during re-treatment (35%) than during the first treatment (7%) (P=0.007). Autoimmune hemolytic anemia developed in four (10%) of the patients during or after re-treatment. Severe infections, including pneumonia and herpes reactivation, occurred in 11 patients during the first treatment and in 10 patients during re-treatment. Twelve (30%) patients died during the study. Infections were the cause of death in six and AIHA in two patients. In conclusion, 2-CdA applied in monotherapy or in combination with prednisone or cyclophosphamide and mitoxantrone has therapeutic activity in some B-CLL patients in whom these drugs induced earlier complete or partial remission. However, since the second response is usually shorter and myelotoxicity more pronounced than during the first therapy, more clinical trials to find other therapeutical approaches are necessary.

Cladribine combined with cyclophosphamide and mitoxantrone as front-line therapy in chronic lymphocytic leukemia

The objective of the study was to determine the effectiveness and the toxicity of a combined chemotherapy consisting of cladribine (2-CdA), mitoxantrone and cyclophosphamide (CMC regimen) in the treatment of previously untreated B cell chronic lymphocytic leukemia (B-CLL). From August 1998 to December 2000 2-CdA was administered at a dosage of 0.12 mg/kg for 3 (CMC3) or 5 (CMC5) consecutive days, mitoxantrone at 10 mg/m2 on day 1 and cyclophosphamide at 650 mg/m2 on day 1 to 62 patients with advanced or progressive B-CLL. The cycles were repeated at 4 week intervals or longer if severe myelosuppression occurred. Twenty patients received CMC5 and 42 patients CMC3. Within the analyzed group an overall response (OR) rate (CR+PR) of 64.5% (95% CI: 52.7-76.3%) was reported, including 29.0% CR. There was no difference in the CR rate between the patients treated with CMC5 (30%) and CMC3 (28.6%) (P = 0.9), nor in the OR rate (55.0% and 69.0%, respectively, P = 0.3). Residual disease was identified in seven out of 18 (38.9%) patients who were in CR, including two treated with CMC5 and five treated with CMC3 protocols. CMC-induced grade III or IV thrombocytopenia occurred in 12 (19.4%) of patients, including four (20%) CMC5-treated and eight (19%) CMC3-treated patients (P= 0.8). Neutropenia grade III or IV was observed in seven (35%) and 11 (26.2%) patients, respectively (P = 0.8). Severe infections, including pneumonia and sepsis, occurred more frequently after CMC5 (11 patients, 55.0%) than CMC3 (10 patients, 28.6%) (P = 0.03) Fourteen patients died, including six treated with CMC5 and eight treated with CMC3 (30% and 19%, respectively). Infections were the cause of death in nine patients, including four in the CMC5 group and five in the CMC3 group. In conclusion, our results indicate that the CMC programme is an active combined regimen in previously untreated B-CLL patients; its efficiency seems to be similar to that observed earlier in B-CLL patients treated with 2-CdA as a single agent. However, toxicity, especially after CMC5 administration, is significant. Therefore, we recommend the CMC3 but not the CMC5 programme for further evaluation.

A phase II study of sequential combination chemotherapy with cyclophosphamide, prednisone, and 2-chlorodeoxyadenosine in previously untreated patients with chronic lymphocytic leukemia

In an earlier study of previously untreated patients with chronic lymphocytic leukemia (CLL), we used a concomitant combination of chlorambucil and 2-chlorodeoxyadenosine and reported overall (OR) and complete (CR) remission rates of 80% and 20%, respectively. After a median follow-up of 5 years, more than 80% of the responders have had a relapse. In the current phase II study of 27 previously untreated patients with CLL, we used a sequential combination of six cycles of intravenous cyclophosphamide (1 g/m2) plus oral prednisone (100 mg/m2 per day for 5 days) followed by two to six cycles of 2-chlorodeoxyadenosine (5 mg/m2 per day for 5 days). The OR and CR rates were 96% and 33%, respectively. After a median follow-up of 29 months, 35% of the responders have had a relapse. Progression-free survival was significantly better in CR patients than in those with partial remission. However, minimal residual disease was phenotypically detected in four of the nine CR patients. Despite the fact that the current OR and CR rates are superior to those seen in a historical cohort treated with a concomitant schedule, a longer follow-up period is needed to assess the durability of these remissions, and a controlled trial is necessary to estimate the impact on overall survival and toxicity.

Quantitation of minimal disease levels in chronic lymphocytic leukemia using a sensitive flow cytometric assay improves the prediction of outcome and can be used to optimize therapy

Previous studies have suggested that the level of residual disease at the end of therapy predicts outcome in chronic lymphocytic leukemia (CLL). However, available methods for detecting CLL cells are either insensitive or not routinely applicable. A flow cytometric assay was developed that can differentiate CLL cells from normal B cells on the basis of their CD19/CD5/CD20/CD79b expression. The assay is rapid and can detect one CLL cell in 10(4) to 10(5) leukocytes in all patients. We have compared this assay to conventional assessment in 104 patients treated with CAMPATH-1H and/or autologous transplant. During CAMPATH-1H therapy, circulating CLL cells were rapidly depleted in responding patients, but remained detectable in nonresponders. Patients with more than 0.01 x 10(9)/L circulating CLL cells always had significant (> 5%) marrow disease, and blood monitoring could be used to time marrow assessments. In 25 out of 104 patients achieving complete remission by National Cancer Institute (NCI) criteria, the detection of residual bone marrow disease at more than 0.05% of leukocytes in 6 out of 25 patients predicted significantly poorer event-free (P =.0001) and overall survival (P =.007). CLL cells are detectable at a median of 15.8 months (range, 5.5-41.8) posttreatment in 9 out of 18 evaluable patients with less than 0.05% CLL cells at end of treatment. All patients with detectable disease have progressively increasing disease levels on follow-up. The use of sensitive techniques, such as the flow assay described here, allow accurate quantitation of disease levels and provide an accurate method for guiding therapy and predicting outcome. These results suggest that the eradication of detectable disease may lead to improved survival and should be tested in future studies.

Stem cell transplantation for chronic lymphocytic leukemia: different outcome after autologous and allogeneic transplantation and correlation with minimal residual disease status

The clinical outcome and its correlation with the status of minimal residual disease (MRD) was analyzed in 26 patients with chronic lymphocytic leukemia (CLL) undergoing stem cell transplantation. All patients having received autotransplant (n = 14) achieved CR which was MRD(-) in nine patients (64%) and MRD(+) in five. With a median follow-up of 26.5 months (range, 12-52), four of the five MRD(+) patients relapsed at 9, 15, 17 and 18 months after transplant, respectively. In contrast, only two patients of the nine MRD(-) patients have relapsed at 15 and 38 months (P = 0.02), and four became MRD(+) at 6, 12, 30, and 42 months after transplantation, respectively. Of the 12 patients that were allografted, three (25%) died in the early post-transplant period, one had resistant disease, and eight (67%) achieved CR. Among the latter, no evidence of MRD post-transplantation was observed in five cases, while a delayed clearance of MRD (up to 22 months after transplantation) was seen in two, and a persistent positivity of MRD after transplant was detectable in another patient until last follow-up (12 months). After a median follow-up of 43 months (range, 15-106), none of the responding patients had clinical or MRD relapse. These results show that in CLL the probability of achieving sustained MRD(-) CR is higher with allogeneic than with autologous transplants, and confirm the value of MRD assessment in the follow-up of patients transplanted for CLL.

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.

Phase II study of 2-chlorodeoxyadenosine in combination with chlorambucil in previously untreated B-cell chronic lymphocytic leukemia

The objective was to determine the safety and efficacy of adding a maximally tolerated dose of 2-chlorodeoxyadenosine (2-CdA) to standard chlorambucil (CLB) therapy in previously untreated B-cell chronic lymphocytic leukemia (CLL). Thirty patients with CLL (median age, 64 years) received two courses of 2-CdA given intravenously (2 mg/m2 daily for 7 days) added to biweekly administration of CLB at 30 mg/m2 given orally. The diagnosis of CLL, treatment indications, and response criteria were according to the National Cancer Institute established guidelines. Sixteen patients (53%) had advanced-stage disease, and four (13%) had trisomy 12 abnormality. The overall remission rate was 80%, including 20% complete remission (CR), 30% nodular partial remission (nPR), and 30% partial remission (PR). Minimal residual disease was detected phenotypically in two of five patients with CR and in eight of nine with nPR. Overall, CR, nPR, and PR rates were not influenced significantly by the presence of cytogenetic abnormalities or advanced clinical stage. With a median follow-up of 33 months, 58% of patients who had a response had relapse. Median time to progression in all 30 patients was 30 months, and time to progression and progression-free survival were not significantly different for the different response groups, clinical stages, or cytogenetic groups. Severe neutropenia and thrombocytopenia occurred in 33% and 7% of patients, respectively. Only two patients had documented bacterial infections, and four had herpetic infections. Concurrent combination chemotherapy with abbreviated doses of 2-CdA and standard-dose CLB is feasible and safe in previously untreated CLL. Antitumor activity may be superior to that of CLB alone given in conventional doses. Whether a different schedule of combining these two agents would result in improved outcome is being investigated.

Clinical Characteristics and Outcome of Young Chronic Lymphocytic Leukemia Patients: A Single Institution Study of 204 Cases

A retrospective analysis on chronic lymphocytic leukemia (CLL) patients ≤55 years observed at a single institution was performed with the purpose of characterizing the clinical features and outcome of young CLL and of identifying patients with different prognostic features. Over the period from 1984 to 1994, 1,011 CLL patients (204 [20%] ≤55 years of age and 807 [80%] >55 years of age) were observed. At diagnosis, younger and older patients displayed a similar distribution of clinical features, except for a significantly higher male/female ratio in younger patients (2.85 v 1.29;P < .0001). Both groups showed an elevated rate of second primary cancers (8.3% v 10.7%), whereas the occurrence of Richter’s syndrome was significantly higher in younger patients (5.9% v 1.2%; P < .00001). Younger and older patients showed a similar overall median survival probability (10 years) but were characterized by a different distribution of causes of deaths: CLL unrelated deaths and second primary malignancies predominated in the older age group, whereas the direct effects of leukemia were prevalent in the younger age group. Although younger and older patients displayed a similar survival, the evaluation of the relative survival rates showed that the disease had a greater adverse effect on the expected survival probability of the younger population. Multivariate analysis showed that for young CLL patients only dynamic parameters, such as lymphocyte doubling time and other signs of active disease, were the independent factors that significantly influenced survival probability (P = .00001). A prolonged clinico-hematologic follow-up allowed us to identify two subsets of young CLL patients with a different prognostic outcome: a group of patients (40%) with long-lasting stable disease without treatment and an actuarial survival probability of 94% at 12 years from diagnosis and another group (60%) with progressive disease and a median survival probability of 5 years after therapy. For the latter patients, the therapeutic effect of innovative therapies with curative intents needs to be investigated in prospective, comparative clinical trials.

Clinical Characteristics and Outcome of Young Chronic Lymphocytic Leukemia Patients: A Single Institution Study of 204 Cases

A retrospective analysis on chronic lymphocytic leukemia (CLL) patients ≤55 years observed at a single institution was performed with the purpose of characterizing the clinical features and outcome of young CLL and of identifying patients with different prognostic features. Over the period from 1984 to 1994, 1,011 CLL patients (204 [20%] ≤55 years of age and 807 [80%] &gt;55 years of age) were observed. At diagnosis, younger and older patients displayed a similar distribution of clinical features, except for a significantly higher male/female ratio in younger patients (2.85 v 1.29;P &lt; .0001). Both groups showed an elevated rate of second primary cancers (8.3% v 10.7%), whereas the occurrence of Richter’s syndrome was significantly higher in younger patients (5.9% v 1.2%; P &lt; .00001). Younger and older patients showed a similar overall median survival probability (10 years) but were characterized by a different distribution of causes of deaths: CLL unrelated deaths and second primary malignancies predominated in the older age group, whereas the direct effects of leukemia were prevalent in the younger age group. Although younger and older patients displayed a similar survival, the evaluation of the relative survival rates showed that the disease had a greater adverse effect on the expected survival probability of the younger population. Multivariate analysis showed that for young CLL patients only dynamic parameters, such as lymphocyte doubling time and other signs of active disease, were the independent factors that significantly influenced survival probability (P = .00001). A prolonged clinico-hematologic follow-up allowed us to identify two subsets of young CLL patients with a different prognostic outcome: a group of patients (40%) with long-lasting stable disease without treatment and an actuarial survival probability of 94% at 12 years from diagnosis and another group (60%) with progressive disease and a median survival probability of 5 years after therapy. For the latter patients, the therapeutic effect of innovative therapies with curative intents needs to be investigated in prospective, comparative clinical trials.

Serum levels of IL-6 type cytokines and soluble IL-6 receptors in active B-cell chronic lymphocytic leukemia and in cladribine induced remission

We have investigated the serum concentrations of interleukin-6 (IL-6) and two IL-6 family cytokines-oncostatin M (OSM) and leukemia inhibitory factor (LIF)-in 63 patients with B-cell chronic lymphocytic leukemia (B-CLL) and 17 healthy controls using the enzyme-linked immunosorbent assay (ELISA) method. Simultaneously, we measured the serum levels of the soluble forms of two subunits of the IL-6 receptor complex-ligand binding glycoprotein 80 (sIL-6R) and glycoprotein 130 (sgp130). The cytokines and receptors were evaluated in 25 untreated patients and 38 patients treated with cladribine (2-CdA), as well as in 17 healthy controls. We have correlated the serum levels of these proteins with Rai's clinical stage of the disease, the response to 2-CdA treatment and some hematological parameters. We have also evaluated the correlation of the IL-6 serum level with the concentration of OSM and IL-6 soluble receptors. IL-6 was measurable in 62/63 (98.4%), OSM in 20/25 (80%) of untreated and 14/38 (37.8%) of the treated patients. sIL-6R and sgp130 were detectable in all 63 patients and LIF in none of the CLL patients. IL-6 serum level in untreated patients was not significantly different as compared to its concentration in the control group (P>0.05). However, in the patients treated with 2-CdA the IL-6 level was significantly lower (P<0.02), and the lowest concentration was found in the patients with complete remission (CR; median 1.4pg/ml; P<0.02). The concentration of sIL-6R was significantly higher in untreated (median 61.8 ng/ml) and treated (median 50.1 ng/ml) CLL patients when compared to normal persons (median 41.2 ng/ml; P=0.04; P<0.001, respectively). There was no difference between the sIL-6R levels in the patients with CR and the healthy controls. In non-responders sIL-6R concentration was the highest and similar to its level in the untreated patients. OSM level was higher in the untreated patients (median 1.8pg/ml) than in the normal controls (median 0.0pg/ml; P<0.001) and in the CR patients (median 0.0pg/ml; P<0.03). The serum concentration of sgp130 was similar in the untreated (median 480 pg/ml) and treated (median 470 pg/ml) patients, as well as in the healthy persons (median 420 pg/ml; P>0.05). We have found significant positive correlation between the levels of sIL-6R and the lymphocytes count in CLL patients (p=0.423; P<0.001). In addition, sIL-6R and OSM serum concentrations correlated also with CLL Rai stage. In conclusion, the serum level of IL-6, OSM and sIL-6R, but not LIF and sgp130, are useful indicators of CLL activity.