In vitro antileukemic activity of novel adenosine derivatives bearing boron cluster modification.

A series of adenosine derivatives bearing a boron cluster were synthesized and evaluated for their cytotoxicity against primary peripheral mononuclear cells from the blood of 17 patients with leukemias (16 CLL and 1 very rare PLL), as well as from 5 healthy donors used as a control. Among the tested agents, two, i.e., compounds 1 and 2, displayed high in vitro cytotoxicity and proapoptotic potential on leukemic cells, with only scarce activity being seen against control cells. Biological tests related to apoptosis revealed the activation of the main execution apoptotic enzyme, procaspase-3, in CLL and PLL cells exposed to compounds 1 and 2. Moreover, the above compounds indicated high activity in the proteolysis of the apoptotic markers PARP-1 and lamin B1, fragmentation of DNA, and the induction of some changes in the expression of the Mcl-1, protein apoptosis regulator in comparison with control cells.

Prognostic value of thymidine kinase activity in patients with chronic lymphocytic leukemia.

Thymidine kinase (TK) activity is a marker of biological activity that allows the indolent and aggressive forms of chronic lymphocytic leukemia (CLL) to be distinguished. The aims of the study were to determine the relationship between TK activity and clinical status and prognosis, as well as to compare its activity with that of other prognostic and predictive factors. TK activity was measured in patient sera at the time of diagnosis using the DiviTum method, with the mean value being 439 Du/L. A correlation was found between TK activity and risk of disease progression (p=0.045). The optimal discriminative value of TK activity in the prediction of CLL progression was found to be 600 Du/L. TK activity significantly differed between the patients who achieved complete remission and those who only partially responded to therapy. In 93% of patients without any response to treatment and 18 out of 20 patients with progressive disease, TK activity over 600 Du/L was noted. In addition, all of the 10 patients with 17p13 deletion displayed TK activity of over 600 Du/L (p=0.0004). High TK activity also correlated with elevated levels of LDH (p=0.001) and ß2­microglobulin (p=0.03) in the study group. The results of the study indicated the importance of TK activity as a prognostic factor in patients with CLL.

Clonal evolution in CLL patients as detected by FISH versus chromosome banding analysis, and its clinical significance.

The acquisition of new aberrations during the course of chronic lymphocytic leukemia (CLL) named clonal evolution (CE) is usually detected by one of the two methods: chromosome banding analysis (CBA) and interphase fluorescence in situ hybridization (I-FISH). The purpose of this study was to compare the usefulness of FISH and CBA for detecting CE and to evaluate its influence on clinical outcome. FISH and CBA were performed at two time points: baseline and follow-up. Thirty-eight previously untreated patients with CLL were included in this study. CBA and I-FISH revealed CE in 15 (39.5%) and 10 (26.3%) patients, respectively. High-risk CE was detected in six cases by CBA and in five cases by I-FISH. In four cases with CE-dependent 17p abnormalities detected by CBA, metaphase FISH was needed for the confirmation of 17p13.1 deletion. Time from first-line to second-line treatment (TTST) and overall survival (OS) did not differ between patients with and without CE, irrespective of the CE-detecting method used. However, shorter OS (P = 0.043) and TTST (P = 0.006) were observed for the patients with potentially relevant CE (rCE) detected by CBA, in which acquired aberrations were present in at least 20% of undivided cells and/or changed baseline karyotype to abnormal or complex and were not resulting from 13q deletion. Our results suggest that some, but not all, CE-dependent aberrations detected by CBA influence clinical outcome. Moreover, I-FISH, which was aimed at detecting aberrations of prognostic significance, was found to be more precise than CBA in their detection, especially TP53 deletion.

Cytotoxic and apoptosis-inducing effects of bendamustine used alone and in combination with rituximab on chronic lymphocytic leukemia cells in vitro.

AIM: The aim of our study was to compare the cytotoxic effects of bendamustine (BENDA) and rituximab (RIT) used either alone or in combination and to evaluate the influence of the above mentioned drugs on apoptosis measured as changes in mitochondrial transmembrane potential (Δψm), expression of caspases and selected apoptosis-regulating proteins in freshly isolated peripheral blood mononuclear cells of chronic lymphocytic leukemia (CLL) patients. MATERIALS/METHODS: Cytotoxic effect of tested drugs, as well as induction of apoptosis, drop in Δψm and expression of selected proteins involved in regulation of apoptosis were assessed in 48 hour cultures containing autologous serum (AS) using flow cytometry. BENDA was used at the concentration of 40 µg/ml and RIT at the concentration of 10 µg/ml. Control cultures were incubated without drugs. RESULTS: BENDA used either alone or in combination with RIT strongly induced apoptosis as well as enhanced expression of selected apoptotic proteins, especially those involved in the intrinsic apoptotic pathway: P53, PUMA and BAX, which cause mitochondrial transmembrane potential changes leading to activation of caspase-9 and -3. CONCLUSIONS: Our results indicate that both BENDA and RIT participate in the induction of apoptosis of CLL lymphocytes in vitro in the presence of AS in the culture medium. The drug-induced apoptosis occurs mainly via intrinsic pathway and activation of P53 and PUMA proteins, however the extrinsic pathway is likely to be involved as well. We also found that the combination of these drugs induces the expression of P53, caspase-8 and -9 more potently than either of them used separately.

Immune thrombocytopenia in patients with chronic lymphocytic leukemia treated with cladribine-based regiments or chlorambucil--follow-up of PALG-CLL randomized trials.

OBJECTIVES: The relationship between treatments of chronic lymphocytic leukemia (CLL) with cladribine (2-CdA) or chlorambucil and immune thrombocytopenia (IT) has not been yet determined. METHODS: The records of 777 patients in two randomized Polish Adult Leukemia Group (PALG)-CLL programs treated with these agents were retrospectively analyzed. RESULTS: Immune thrombocytopenia occurred in 55 of 777 (7.1%) patients. No significant differences in IT prevalence were seen between patients on chlorambucil or 2-CdA-based regiments (P = 0.33). IT developed at a median time of 0.499 yr (0.06-4.8) from the start of CLL therapy. This time was significantly longer in patients treated with chlorambucil (2.03 yr, 95% CI: 0.06-4.22) in relation to patients treated with 2-CdA-based regiments (0.52 yr, 95%CI: 0.34-0.69, P = 0.049). Overall survival (OS) of patients with IT and those without IT were similar (2.65 yr vs. 3.2 yr P = 0.23) but the severity of bleeding was more pronounced in the 2-CdA group. The responses to IT therapy were 35%, 54% and 75% for steroids, chemotherapy and splenectomy, respectively. CONCLUSIONS: In this study, an unexpectedly high percentage of IT incidence was demonstrated in patients with CLL requiring chemotherapy. Although no marked differences were seen in IT frequency in patients treated with 2-CdA-based regiments compared to chlorambucil regimen, the clinical course of hemorrhagic diathesis was more severe in 2-CdA group. Also, the time elapsed from study screening to IT diagnosis was significantly shorter in the 2-CdA group than in the chlorambucil group suggesting a causative relationship. The appearance of IT did not influence the median time of OS.

R-roscovitine (Seliciclib) affects CLL cells more strongly than combinations of fludarabine or cladribine with cyclophosphamide: Inhibition of CDK7 sensitizes leukemic cells to caspase-dependent apoptosis.

Chronic lymphocytic leukemia (CLL) is characterized by the accumulation of malignant, apoptosis-resistant B CD19(+)/CD5(+) cells. Populations of CLL cells are heterogeneous and consist primarily of quiescent cells with a minor subset of dividing cells. In this study the efficacy of a first-line in vivo therapy was compared with treatment by R-roscovitine (ROSC) alone or by purine analogues (cladribine and fludarabine) combined with maphosphamide for 14 CLL patients under ex vivo conditions. ROSC induced the highest reduction in numbers of living B-cells, coinciding with an increased rate of apoptosis. After 24 h the percentage of apoptotic cells in ROSC-treated cultures was markedly higher than in untreated controls. ROSC also induced strong activation of the apoptosome and effector caspases in CLL cells. During progression of apoptosis the plasma membrane became permeable, resulting in the release of activated caspases into the culture medium. Leukemic cells were more sensitive to ROSC than normal mononuclear cells. Treatment with ROSC did not affect the activating phosphorylation of CDK2 or CDK1. However, ROSC decreased phosphorylation of survivin, CDK7, and RNA-Pol II, resulting in inhibition of transcription elongation and subsequent down-regulation of levels of anti-apoptotic factors, thereby facilitating apoptosis. Unlike ROSC, two other purine analogues barely affected the cellular levels of anti-apoptotic proteins and more weakly activated effector caspases. In addition, the efficacies of in vivo and ex vivo therapies were found to be correlated. Marked between-patient differences in expression patterns of apoptosis-regulating factors in CLL cells were observed, explaining the variations in patients' sensitivity to therapy.

Dose and drug changes in chronic lymphocytic leukemia cell response in vitro: A comparison of standard therapy regimens with two novel cyclin­dependent kinase inhibitors.

Chronic lymphocytic leukemia (CLL) treatment is improving; however, some patients do not respond to therapy. Due to the high heterogeneity in disease development, there is an urgent need for personalization of therapy. In the present study, the response of leukemic mononuclear cells to anticancer drugs used for CLL treatment (cladribine + mafosfamide; CM or CM combined with rituximab; RCM) was compared with the response to new cyclin­dependent kinase (CDK) inhibitors: BP14 and BP30. Viable apoptotic and necrotic cells were quantified by flow cytometry using propidium iodide and Yo­Pro stains. CDK inhibitors were studied in several doses to determine the reduction of necrosis and simultaneous increase of apoptosis in leukemic cell incubations with anticancer agents. The distinct cell response to applied doses/anticancer agents was observed. Results obtained in the current manuscript confirmed that modulation of doses is important. This was particularly indicated in results obtained at 24 h of cells incubation with anticancer agent. While an important time for analysis of anticancer response efficacy (monitoring of apoptosis induction potential) seems to be 48 h of cells exposition to anticancer agents. High variability in response to the drugs revealed that both the nature and the dose of the anticancer agents could be important in the final effect of the therapy. The present findings support the thesis that personalized medicine, before drug administration in the clinic, could be important to avoid the application of ineffective therapy.

Bendamustine alone or with rituximab modifies expression of apoptosis-regulating genes and proteins of CLL cells, depending on IGVH mutational status.

We studied whether bendamustine (BENDA) alone or with rituximab (RIT) modifies in vitro expression of apoptosis-involved genes and proteins of chronic lymphocytic leukemia (CLL) cells depending on IGVH mutational status. Circulating lymphocytes from 34 untreated patients (18 IGVH-MUT and 16 IGVH-UNMUT) were incubated with above drugs to evaluate proteins expression. Microarray analysis of 93 genes was performed in 14 patients. BENDA and BENDA + RIT increased expression of BAX and BBC3 in IGVH-MUT and IGVH-UNMUT groups, and significant differences in expression of above genes after BENDA + RIT were observed between both groups. Additionally, BENDA + RIT decreased NFκB and BCL-2 genes in IGVH-UNMUT patients and increased expression of P53, BAX and PUMA proteins in IGVH-MUT and UNMUT subjects. However, no significant differences were found between these groups. In conclusion, BENDA + RIT modified gene expression profile in CLL cells and affected expression of some apoptosis-regulating proteins in vitro. Expression of BAX and BBC3 depends on action of drugs and IGVH mutational status.

Forodesine (BCX-1777, Immucillin H)--a new purine nucleoside analogue: mechanism of action and potential clinical application.

Recently a few new purine nucleoside analogues (PNA) have been synthesized and introduced into preclinical and clinical trials. The transition-state theory has led to the design of 9-deazanucleotide analogues that are purine nucleoside phosphorylase (PNP) inhibitors, termed immucillins. Among them the most promising results have been obtained with forodesine. Forodesine (BCX-1777, Immucillin H, 1-(9-deazahypoxanthin)-1,4-dideoxy-1,4-imino-D-ribitol) has carbon-carbon linkage between a cyclic amine moiety that replaces ribose and 9-deaza-hypixanthine. The drug is a novel T-cell selective immunosuppressive agent which in the presence of 2'-deoxyguanosine (dGuo) inhibits human lymphocyte proliferation activated by various agents such as interleukin-2 (IL-2), mixed lymphocyte reaction and phytohemagglutinin. In the mechanism of forodesine action two enzymes are involved: PNP and deoxycytidine kinase (dCK). PNP catalyzes the phosphorolysis of dGuo to guanine (Gu) and 2'-deoxyribose-1-phosphate, whereas dCK converts dGuo to deoxyguanosino-5'-monophosphate (dGMP) and finally to deoxyguanosino-5'-triphosphate (dGTP). The affinity of dGuo is higher for PNP than for dCK. Nevertheless, if PNP is blocked by forodesine, plasma dGuo is not cleaved to Gu, but instead it is intracellularly converted to dGTP by high dCK activity, which leads to inhibition of ribonucleotide reductase (RR), an enzyme required for DNA synthesis and cell replication, which eventually results in apoptosis. Forodesine is active in some experimental tumors in mice, however it could be used for the treatment of human T-cell proliferative disorders and it is undergoing phase II clinical trials for the treatment of T-cell non-Hodgkin's lymphoma, which includes cutaneous T-cell lymphoma (CTCL). Moreover, recent preclinical and clinical data showed activity of forodesine in B-cell acute lympholastic leukemia (ALL).

Personalized therapy tests for the monitoring of chronic lymphocytic leukemia development.

There is individual variation in the course of disease development and response to therapy of patients with chronic lymphocytic leukemia (CLL). Novel treatment options for CLL include a new generation of purine analogs, antibodies and inhibitors of specific cell signaling pathways, which typically induce apoptosis or necrosis. A prospective analysis of patient blood samples revealed that a combination of four tests allowed the most appropriate and effective type of treatment to be selected prior to drug administration, and for the analysis of leukemic cell sensitivity to anticancer drug(s) during disease development. The comparative analysis of blood from the stable and progressive form of CLL in an individual patient revealed diversity in the response to anticancer agents. CLL peripheral blood mononuclear cells were incubated with cladribine + mafosfamide (CM), fludarabine + mafosfamide, CM + rituximab, rituximab alone (Rit) or kinetin riboside (RK). A combination of cell viability, differential scanning calorimetry (DSC) profiles of nuclear preparations and poly(ADP-ribose) polymerase 1 (PARP-1) protein expression analysis of the leukemic cells was performed to evaluate the anticancer effects of the tested agents during CLL development. The results of the present study indicate that such studies are effective in determining the most appropriate anticancer drug and could monitor disease progression on an individual level. In addition, the results of the current study suggest that CLL progression leads to diversification of the cellular drug response. The most efficient apoptosis inducer for the patient was purine analog RK when the disease was stable, while the CM combination was the most effective agent for the progressive form of disease.

Health-related quality of life and patient-reported outcomes of ofatumumab plus fludarabine and cyclophosphamide versus fludarabine and cyclophosphamide in the COMPLEMENT 2 trial of patients with relapsed CLL.

Chronic lymphocytic leukemia (CLL) is an incurable disease. Quality of life during treatment and periods of subsequent remission is therefore vital. Health-related quality of life (HRQoL) was compared in relapsed CLL during and after treatment with ofatumumab combined with fludarabine and cyclophosphamide versus fludarabine and cyclophosphamide alone. The European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 v3 and QLQ-CLL16 were used to assess HRQoL in this open-label, phase 3 study. Improvements in prespecified domains of patient-reported outcomes (Global Health Status [GHS]/HRQoL and B symptom scores) were recorded in both treatment arms after three cycles and were sustained after 18 months of follow-up. The two treatment arms were not significantly different at the nominal 0.05 level for GHS/HRQoL (p = .7278) or B symptoms (p = .5968). Small improvements in quality of life were maintained after therapy. The addition of ofatumumab was without any adverse impact on HRQoL (NCT00824265).

Ofatumumab plus fludarabine and cyclophosphamide in relapsed chronic lymphocytic leukemia: results from the COMPLEMENT 2 trial.

In this multicenter, open-label, phase III study, patients with relapsed chronic lymphocytic leukemia (CLL) were randomized (1:1) to receive ofatumumab plus fludarabine and cyclophosphamide (OFA + FC) or FC alone; the primary endpoint being progression-free survival (PFS) assessed by an independent review committee (IRC). Between March 2009 and January 2012, 365 patients were randomized (OFA + FC: n = 183; FC: n = 182). Median IRC-assessed PFS was 28.9 months with OFA + FC versus 18.8 months with FC (hazard ratio = 0.67; 95% confidence interval, 0.51-0.88; p = .0032). Grade ≥3 adverse events (≤60 days after last dose) were reported in 134 (74%) OFA + FC-treated patients compared with 123 (69%) FC-treated patients. Of these, neutropenia was the most common (89 [49%] vs. 64 [36%]). OFA + FC improved PFS with manageable safety for patients with relapsed CLL compared with FC alone, thus providing an alternative treatment option for patients with relapsed CLL. TRIAL REGISTRATION: www.clinicaltrials.gov (NCT00824265).

In vitro sensitivity of B-cell chronic lymphocytic leukemia to cladribine and its combinations with mafosfamide and/or mitoxantrone.

We examined in vitro sensitivity of B-CLL cells exposed to cladribine, mafosfamide, mitoxantrone and combinations ofcladribine with mafosfamide and/or mitoxantrone. The results revealed that each applied treatment of leukemic cells, besides having a cytotoxic effect, affected the events associated with apoptosis. All drugs used alone, and cladribine combinations with mafosfamide and/or mitoxantrone induced DNA fragmentation and the changes in expression/proteolysis level of caspase-3, caspase-9 precursors, PARP-1, lamin B, Bax and Bcl-2; however, each to a different degree. The exposure of leukemic cells to both cladribine combinations induced stronger effects. Moreover, the data showed that the expression of regulatory antiapoptotic protein Bcl-2 generally decreased in drug-treated B-CLL cells, whereas proapoptotic polypeptide Bax increased, resulting in enhancement of Bax-Bcl-2 ratios in comparison with untreated cells. Drug-treatment of the studied cells induced the translocation of Bax protein from the cytosol to the cellular pellet, containing mitochondria, where this polypeptide indicated the capacity for oligomerization. These observations suggest that the examined drugs are able to induce apoptosis of B-CLL cells via the mitochondria pathway.

Antibody therapy alone and in combination with targeted drugs in chronic lymphocytic leukemia.

The development of non-chemotherapeutic agents, including monoclonal antibodies (mAbs) and other targeted drugs, makes chemotherapy-free treatment an attractive option for chronic lymphocytic leukemia (CLL). The classical mAb, rituximab, has been authorized for use in both first-line and second-line therapy for CLL. New mAbs directed against CD20, ofatumumab, and obinutuzumab (GA-101) have also been approved for the treatment of this disease. Recently, several new mAbs with potential benefits over the approved anti-CD20 antibodies have been developed for use in CLL. Anti-CD37, anti-CD19, and anti-CD40 mAbs are in early clinical trials and show promise in treating CLL. In addition, the combination of mAbs with B-cell receptor signaling pathway inhibitors and immunomodulatory drugs makes the chemotherapy-free option a reality today. Combinations of antibodies with targeted drugs like ibrutinib, idelalisib, or lenalidomide are expected to replace chemotherapy-based combinations for treating CLL in the near future. However, phase III trials should confirm the benefit of these new treatment strategies and establish their exact place in the therapeutic armamentarium for CLL.

The effect of subsequent therapies in patients with chronic lymphocytic leukemia previously treated with prednisone and either cladribine or chlorambucil.

We present the long-term follow-up and results of subsequent treatments in patients with chronic lymphocytic leukemia treated initially with cladribine + prednisone or chlorambucil + prednisone in a randomized, cross-over study. We found higher complete and overall responses rates in patients who received cladribine + prednisone as first and second-line treatment but no significant differences in survival.

Changes in leukemic cell nuclei revealed by differential scanning calorimetry.

Using differential scanning calorimetry we analyzed the thermal profiles of nuclei from normal and B-cell chronic lymphocytic leukemia mononuclear cells. Intact nuclear fraction of normal mononuclear cells is characterized by four thermal transitions, i.e., at 60, 70, 83 and 103 degrees C. Leukemic nuclear samples revealed the transitions at 67 and 83 degrees C, however, in more aggressive stage of the disease additional thermal peaks at 76 and 93 degrees C were observed. Our very preliminary results revealed that mononuclear cell nuclear fraction from blood of patients responding to the used therapy, i.e., cladribine alone or its combination with mitoxantrone and cyclophosphamide indicates decrease (or even loss) of transition at 93 degrees C concomitant with increase of transition at 76 degrees C. A complementary study showed that in mononuclear cells of patients who appeared to be sensitive to chemotherapy the decrease of antiapoptotic Bcl-2 protein expression and signs of apoptotic morphology were observed.

Circulating vascular endothelial growth factor (VEGF) and its soluble receptors in patients with chronic lymphocytic leukemia.

UNLABELLED: The vascular endothelial growth factor (VEGF) transduction pathway may be very active in B-cell chronic lymphocytic leukemia (B-CLL) cells and contributes to their enhanced survival. Vascular endothelial growth factor receptor-1 (VEGFR-1) and receptor-2 (VEGFR-2), are the high-affinity VEGF receptors, which play an important role in de novo blood vessel formation and hematopoietic cell development. The aim of our study was to compare the concentration of VEGF, VEGFR-1 and VEGFR-2 in the serum of 83, never-treated B-CLL patients in different stage of disease according to Rai classification, and 20 healthy volunteers. Of all the cytokines only the serum concentration of VEGF was found to be significantly higher in the CLL group when compared to the control group (median 468.2 pg/mL and 246.9 pg/mL, respectively) (p = 0.01). In the group of CLL patients, the serum concentrations of VEGF and VEGFR-2 were significantly higher in patients in Rai stage III and IV (median 890.0 pg/mL and 4680.4 pg/mL respectively) than in patients in Rai stage 0-II (347.8 pg/mL and 2411.6 pg/mL respectively) (p<0.0001). In the entire group of CLL patients, we have found a strong, positive correlation between the serum level of VEGF and VEGFR-2 (p = 0.00001, R = 0.46). We have also found a positive correlation between the number of lymphocytes in the peripheral blood of CLL patients and the level of VEGF (p = 0.05, R = 0.24) and VEGFR2 (p = 0.02, R = 0.29). IN CONCLUSION: VEGF and VEGF R2, but not VEGF R1, may have an important influence on the course of B-CLL.

Relationship between in vitro drug sensitivity and clinical response of patients to treatment in chronic lymphocytic leukemia.

To improve the efficacy of therapeutic options in chronic lymphocytic leukemia (CLL) an in vitro system to determine the response of mononuclear blood cells from blood of patients was elaborated. The study combines four approaches, i.e., cell viability, apoptosis rate, differential scanning calorimetry (DSC), and immunoblotting to develop personalized therapy protocols based on the cell sensitivity to drug exposure of individual CLL patients. The complementary analyses were performed on 28 peripheral blood samples from previously untreated CLL patients before therapy. The induction and progress of apoptosis in CLL cells exposed in vitro to purine analogs combined with mafosfamide, i.e., cladribine + mafosfamide (CM) and fludarabine + mafosfamide (FM) were assessed using the above approaches. The changes in thermal profiles (decrease/loss of transition at 95±5˚C) coincided with an accumulation of apoptotic cells, a decrease in the number of viable cells, and differences in the expression of the apoptosis­related protein PARP­1. No significant changes were observed in the thermal profiles of nuclei isolated from CLL cells resistant to the treatment. The complementary assays revealed a strong relationship between both the in vitro sensitivity of leukemia cells to drugs and the clinical response of the patients, determined usually after the sixth course of treatment (after ~6 months of therapy). As a summary of studies followed by complementary tests, our findings demonstrate the value of in vitro exposure of CLL cell samples to drugs intended to treat CLL patients, before their administration in order to recommend the most suitable and effective therapy for individual patients.

Cladribine combined with cyclophosphamide is highly effective in the treatment of chronic lymphocytic leukemia.

The aim of the study was to evaluate the activity and toxicity of cladribine (2-CdA) in combination with cyclophosphamide (CY), the CC schedule, in patients with previously untreated B-cell chronic lymphocytic leukemia (B-CLL). From November 1998 to May 2002 82 patients with advanced or progressive B-CLL received treatment with 2-CdA at a dose of 0.12 mg/kg for three consecutive days and CY at a dose of 650 mg/m(2) on day 1. The cycles were repeated at four week intervals or longer if severe myelosuppression occurred. Guidelines for the evaluation of response and toxicity were those developed by the National Cancer Institute sponsored Working Group. Minimal residual disease (MRD) was detected by immunophenotyping only in patients with CR by standard criteria. In the analysed group an overall response (OR) rate (CR+PR) of 87.8% (95% CI 80.7-94.9%) was achieved, including complete response (CR) in 29.3% patients (95% CI 19.4-39.1%). Twenty-two of 24 patients with CR and 39 of 48 patients with PR are still in remission. Median duration of follow-up in these patients is 11.8 months (range 3-25.4). MRD was only detected in six out of 24 (25%) patients with CR. Grade III/IV thrombocytopenia was seen in four patients (4.9%) and neutropenia in 10 (12.2%). Severe infections were noted in 21 (25.6%) patients. Thirteen patients died, including seven with treatment related toxicity, one because of CLL progression and five because of reasons not related to CLL. In conclusion, the CC schedule is a highly active regimen in previously untreated B-CLL, with acceptable toxicity. The efficacy of the regimen seems to be higher than observed earlier after treatment with 2-CdA alone. A randomized clinical trial is in progress in our institutions.

Rituximab followed by cladribine in the treatment of heavily pretreated patients with indolent lymphoid malignancies.

The purpose of this study was to determine the efficacy and toxicity of combined therapy consisting of rituximab (RIT), an anti-CD20 monoclonal antibody, and cladribine (2-chlorodeoxyadenosine, 2-CdA) (RC regimen) in patients with refractory or relapsed indolent lymphoproliferative disorders. Twenty six CD20 antigen positive patients, 15 with B-cell chronic lymphocytic leukemia (B-CLL) and 11 with low grade non-Hodgin's lymphoma (LG-NHL) were enrolled to the study. Fourteen patients (53.8%) had refractory disease, the other 12 (46.2%) were recurrent after prior chemotherapy. RC regimen consisted of RIT at a dose of 375 mg/m2 in 6 h infusion on day 1 and 2-CdA at a dose of 0.12 mg/kg, in 2 h infusion, given on days 2-6. The RC courses were repeated at 4 week intervals or longer if severe myelosuppression occurred. Seventy eight cycles of RC with median of 3 cycles per patient were administered (range 1-5 cycles). Four patients (15.4%) (95% CI 1.5-29.3%), 1 with B-CLL and 3 with LG-NHL, achieved a complete response (CR). Fourteen patients (53,8%) (95%CI 34.6-72.9%), including 10 with B-CLL and 4 with LG-NHL, had a partial response (PR). Overall response rate (OR) was 69.2% (95%CI 51.4-86.9%) in the whole group, from 63.6% (95% CI 35.2 92.0%) in LG-NHL to 73.3% (95%CI 50.1-95.7%) in B-CLL patients. Twelve of 18 patients with CR/PR are still in remission, with the median follow up 10 (7-28 months). The median failure-free survival (FFS) of responders was 6.5 months. Hypersensitivity to RIT was the major toxicity of RC regimen, and occurred in 9 patients (34.6%), mostly only during the first infusion of RIT. Severe neutropenia (grade III) was seen in 3 patients (11.5%). Anemia and thrombocytopenia associated with RC treatment were observed in 5 (19.2%) and 2 patients (7.7%), respectively. Four episodes (15.4%) of grade III-IV infections were observed. There was no treatment related mortality. During the follow-up six patients (23.1%) died from the disease progression. In conclusion, the combination of RIT and 2-CdA is an effective and well tolerated treatment, even for heavily pre-treated patients, and the results seem to be better than in patients previously treated in our institution with 2-CdA alone. This regimen can be considered as an alternative treatment of CD-20 positive indolent lymphoproliferative disorders.