Early induction intensification with cladribine, cytarabine, and mitoxantrone (CLAM) in AML patients treated with the DAC induction regimen: a prospective, non-randomized, phase II study of the Polish Adult Leukemia Group (PALG)

We present the results of a prospective, non-randomized phase 2 trial in which 253 AML patients (pts) under 60 years old received DAC (Daunorubicin + AraC + Cladribine) as first induction followed by CLAM (Cladribine + AraC + Mitoxantrone) as early second induction on day 16 based on bone marrow (BM) blasts on day 14 (D14). The CR/CRi rate after a single course of DAC was 83% for pts with D14 BM blasts less than 10%. Forty-six pts had >10% BM blasts on D14, of whom 35 received CLAM with rates of CR/CRi 60% and early death (ED) 23%. The remaining 11 pts were not fit to receive CLAM, with rates of CR/CRi 28%, PR 18%, and ED 18%. Median OS was 7.2 versus 7.5 months, respectively. The overall CR/CRi rate was 77% after the first induction, with final CR/CRi rate 80% after DAC reinduction for pts who achieved PR with initial DAC course. CLAM used as early second induction might improve CR/CRi rates for younger AML pts with poor early response to DAC induction, but may be associated with higher mortality.

The kinetics of hematopoietic niche cytokines and their influence on mobilization efficacy and timing in patients with hematological malignancies

The bone marrow niche functions are modulated by complicated cytokines network. The aim of our study was to evaluate the levels of VCAM-1, VEGF, MMP-9 and SDF during mobilization of CD34+ cells in patients with hematological malignancies. Thirty four patients were enrolled to the study (19F, 15 M) at median age of 57 years. The group consisted of patients with multiple myeloma (26) and lymphoma (8). The mobilization procedures comprised chemotherapy and then G-CSF. Blood samples were collected before chemotherapy (N = 34) and on the day of the first apheresis (N = 26). Cytokines were evaluated with ELISA assay. We observed significant increase in VCAM-1 levels during mobilization. On contrary, VEGF and SDF levels decreased during mobilization procedure. The levels of MMP-9 were stable during mobilization. We divided patients according to baseline cytokines levels below and above median into "low" and "high" expressors. The group of VEGF "low" expressors had longer median time of G-CSF treatment before first apheresis than 'high' expressors. Baseline VEGF levels correlated adversely with duration of G-CSF treatment before first apheresis. Patients were also divided according to median cytokines levels at apheresis into "low" and "high" expressors. "High" VCAM-1 expressors had higher CD34+in peripheral blood as well as higher CD34+numbers collected during first apheresis than "low" expressors. In conclusion, the levels of niche cytokines change significantly during mobilization in patients with hematopoietic malignancies. Baseline VEGF can influence timing of mobilization. Higher VCAM-1 corresponds with higher mobilization efficacy.

Jagged-1: a new promising factor associated with favorable prognosis in patients with acute myeloid leukemia

In this study Jagged-1 and Dll-1 surface expression as well as Notch-1 receptor intracellular domain (Notch-1-IC) expression were assessed by multi-color flow cytometry in leukemic blasts obtained from 88 patients with acute myeloid leukemia (AML). CD34+peripheral blood stem cells (PBSCs) were used as a control. The median expression of Jagged-1 and Dll-1 was significantly higher in AML blasts than in PBSCs (p=0.001 and p=0.002, respectively). Higher expression of Notch-1-IC was detected in patients with poor-risk karyotype as compared to good- and intermediate-risk groups (p=0.035). In our study, poor-risk cytogenetics and low (<median) expression of Jagged-1 were the only factors associated with significantly shorter overall survival in intensively treated patients according to multivariate analysis. In conclusion, high Jagged-1 surface level in leukemic cells is an independent favorable prognostic factor in patients with AML. To our knowledge, this is the first study evaluating the prognostic role of Notch-1-IC in AML blasts.

Hematopoietic stem cell mobilization with the reversible CXCR4 receptor inhibitor plerixafor (AMD3100)-Polish compassionate use experience

Recent developments in the field of targeted therapy have led to the discovery of a new drug, plerixafor, that is a specific inhibitor of the CXCR4 receptor. Plerixafor acts in concert with granulocyte colony-stimulating factor (G-CSF) to increase the number of stem cells circulating in the peripheral blood (PB). Therefore, it has been applied in the field of hematopoietic stem cell mobilization. We analyzed retrospectively data regarding stem cell mobilization with plerixafor in a cohort of 61 patients suffering from multiple myeloma (N = 23), non-Hodgkin’s lymphoma (N = 20), or Hodgkin’s lymphoma (N = 18). At least one previous mobilization attempt had failed in 83.6% of these patients, whereas 16.4% were predicted to be poor mobilizers. The median number of CD34+ cells in the PB after the first administration of plerixafor was 22/μL (range of 0–121). In total, 85.2% of the patients proceeded to cell collection, and a median of two (range of 0–4) aphereses were performed. A minimum of 2.0 × 10⁶ CD34+ cells per kilogram of the patient’s body weight (cells/kg b.w.) was collected from 65.6% of patients, and the median number of cells collected was 2.67 × 10⁶ CD34+ cells/kg b.w. (0–8.0). Of the patients, 55.7% had already undergone autologous stem cell transplantation, and the median time to neutrophil and platelet reconstitution was 12 and 14 days, respectively. Cases of late graft failure were not observed. We identified the diagnosis of non-Hodgkin’s lymphoma and previous radiotherapy as independent factors that contributed to failure of mobilization. The current report demonstrates the satisfactory efficacy of plerixafor plus G-CSF for stem cell mobilization in heavily pre-treated poor or predicted poor mobilizers.

Influence of high expression of Smac/DIABLO protein on the clinical outcome in acute myeloid leukemia patients

The role of the Smac/DIABLO protein, a novel apoptosis agonist, in acute myeloid leukemia (AML) is not clearly determined. The expression of Smac/DIABLO protein in AML leukemic cells and its relationship with clinical outcome was evaluated in this study. The intracellular expression of Smac/DIABLO protein was assessed using multi-color flow cytometry in 71 newly diagnosed AML patients treated with conventional chemotherapy. It was found that the high expression of Smac/DIABLO protein was an independent prognostic factor in terms of higher complete remission rate (p<0.001) and longer overall survival (p=0.003). Moreover the low expression of Smac/DIABLO protein was associated with poor karyotype.

Evaluation of circulating endothelial cells as noninvasive marker of angiogenesis in patients with chronic lymphocytic leukemia

An increased angiogenesis has been documented in bone marrow and lymph nodes of patients with chronic lymphocytic leukemia (CLL). There is accumulating evidence that circulating endothelial cells (CECs) play an important role in angiogenesis. The aim of our study was to compare the number of CECs in peripheral blood of CLL patients and healthy donors and to correlate these numbers with bone marrow microvessel density (MVD) and known prognostic factors in CLL. Proportions of resting CECs (rCECs), activated CECs (aCECs), apoptotic CECs (apoCECs) and circulating precursor endothelial cells (CPECs) were estimated by flow cytometry in 104 untreated CLL patients and 29 healthy blood donors. The MVD was analysed in the bone marrow biopsy in 21 CLL patients and 11 controls using the 'hot spot analysis' of vessels' density (x200 HPS). We found significantly higher numbers of CPECs, rCECs, aCECs and apoCECs in CLL patients than in healthy controls (p < 0.001 for all comparisons). Furthermore, the rCECs number was higher in advanced versus low clinical stage CLL (median 17.5 cells/microL vs. 13.5 cells/microL, p = 0.05). The MVD was significantly higher in the bone marrow of CLL patients when compared with controls (p = 0.016). However, we did not find any correlation between MVD and different CECs populations. In conclusion, the number of CECs is increased in CLL and correlates with stage of the disease, but does not seem to directly reflect the intensity of neovascularisaton in the bone marrow.

Human leukocyte antigens HLA DRB1 influence clinical outcome of chronic lymphocytic leukemia

We investigated HLA DRB1 correlations with chronic lymphocytic leukemia (B-CLL) outcome in 90 patients. Neither of the alleles was associated with B-CLL clinical characteristics or mortality. HLA DRB1*01 and HLA DRB1*02-null were associated with shorter overall survival (p=0.007, p=0.002). Our results suggest that HLA-restricted adaptive immunity influences CLL outcome.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Proapoptotic activity of alemtuzumab alone and in combination with rituximab or purine nucleoside analogues in chronic lymphocytic leukemia cells

Proapoptotic activity of anti-CD52 monoclonal antibody, alemtuzumab (ALT) as well as ALT-affected apoptosis-regulatory mechanisms were assessed in tumor cells from 36 patients with chronic lymphocytic leukemia (CLL). Cells were treated in vitro for 24-48 h with ALT alone or in combination with rituximab (RTX), or purine nucleoside analogues (PNA), fludarabine and cladribine. Moreover, eight ALT-treated patients were examined in vivo. In 22/36 patients with the pre-treatment overexpression of Bax, Bak and Bid proteins, ALT induced a distinct (more than 50% from the baseline) increase in the incidence of apoptosis after 24 h of in vitro treatment. ALT-attributed CLL cell apoptosis was also detected after 24 h from in vivo ALT administration, with significantly downregulated Bcl-2 (P = 0.012) and Mcl-1 (P = 0.031). ALT combined with PNA or RTX exerted significantly higher proapoptotic effect in vitro than single agents, downregulating FLIP and Bcl-2 (ALT + PNA) or significantly increasing Bax expression (ALT + RTX; P = 0.007). In conclusion, the evidence of apoptotic CLL cells death in response to ALT, with deregulation of intrinsic apoptotic pathway, is presented. ALT and PNA or RTX trigger complementary changes in expression of proteins regulating cell propensity to undergo apoptosis, what provides molecular rationale for combining ALT with those agents.

Relation of P-glycoprotein expression with spontaneous in vitro apoptosis in B-cell chronic lymphocytic leukemia

Prolonged lifespan of monoclonal lymphocytes in B-cell lymphocytic leukemia (B-CLL) arises from their resistance to programmed cell death. In contrast, when cultured in vitro, B-CLL tumour cells rapidly undergo apoptosis. There is mounting evidence that P-glycoprotein (P-gp), an adenosine triphosphate-binding cassette (ABC) family transporter, plays a significant role in the regulation of apoptosis induced by various stimuli. Since P-gp is commonly expressed in B-CLL cells, we aimed to establish whether its expression level influences resistance to spontaneous apoptosis in B-CLL. For that purpose, P-gp expression by UIC2 antibody staining and P-gp activity by rhodamine 123 (Rh123) efflux in presence or absence of P-gp inhibitor verapamil were studied in peripheral blood lymphocytes obtained from 43 previously untreated B-CLL patients. Simultaneously, the percentage of cells undergoing spontaneous in vitro apoptosis (apoptotic index, AI) by means of activation of caspases and annexin-V-based assays was evaluated. The AI were higher in B-CLL cells than in normal peripheral blood mononuclear cells (medians of AI 27.7% vs 3.9%, p=0.0001 and 34.7% vs 7.4%, p=0.0038, in 24 and 48-hour culture respectively). The AI were also higher among female patients as compared to male patients (medians: 29.7 vs 19.2 p=0.048). Interestingly, we found moderate inverse correlation between P-gp protein expression and AI after 24-hour culture in analysed B-CLL samples (r= -0.36, p=0.019). Moreover, P-gp positive B-CLL samples expressed significantly higher AI than P-gp negative samples with an arbitrary cut-off at Kolmogorov-Smirnov statistics D-value 0.2 (medians of AI 18.4% vs 29.7%, p=0.026). Based on these results we suggest that P-gp expression has some protective effect on B-CLL cell survival in vitro. The difference in the rates of spontaneous apoptosis among male and female patients may contribute to gender-dependent variations in clinical outcome in B-CLL.

Evaluation of apoptosis induced in vitro by cladribine (2-CdA) combined with anthracyclines in lymphocytes from patients with B-cell chronic lymphocytic leukemia

The aim of the study was to evaluate the effect of three anthracyclines [doxorubicin (DOX), mitoxantrone (MIT), and idarubicin (IDA)] on the rate of apoptosis triggered by 2-chlorodeoxyadenosine (2-CdA) in peripheral blood mononuclear cells isolated from 52 untreated patients with B-cell chronic lymphocytic leukemia (B-CLL). The cells were cultured up to 48 h in the presence of drugs alone and in the following combinations: 2-CdA+DOX, 2-CdA+MIT, and 2-CdA+IDA. Apoptosis was assessed after 24 h and 48 h of incubation using annexin V/propidium iodide assay by flow cytometry. The apoptotic index (AI) was defined as a percentage of annexin V-positive B-CLL cells. Additionally, in some patients other hallmarks of apoptosis (activation of caspases, DNA fragmentation) were assessed in parallel for confirmation of apoptotic mode of induced cell death. All of the cytostatics induced apoptosis of B-CLL cells at a rate significantly higher than the index of spontaneous apoptosis occurring during 24 h and 48 h of cell culture. 2-CdA in combination with DOX significantly increased the percentage of annexin V-positive cells, particularly after 48 h of incubation, as compared with DOX used in monotherapy (median AI for 2-CdA+DOX=37.9%, median AI for DOX =13.8%, P=0.0011, and median AI for 2-CdA=22.1%, P=0.013). Combination of 2-CdA with MIT induced a similar effect, also more distinct after 48 h (median AI for 2-CdA+MIT=41.05%, median AI for MIT=16.3%, p=0.0012, and median AI for 2-CdA=22.1%, p=0.017). For both combinations median AI were similar to the sum of median AI for each drug when used alone. IDA in a concentration ten times lower (0.1 micro g/ml) than used before in acute leukemia cells produced high cytotoxic effects, masking the additive effect of combination with 2-CdA. Only at a dose of 25 ng/ml of IDA, significant differences in AI after 24 h and 48 h were detected between samples treated with 2-CdA+IDA (median 27.5% and 65.0%, respectively) and those incubated with IDA alone (median 10.5% and 33.4%; P=0.0004 and 0.0274, respectively). Similarly, there were significant differences between AI of cells treated with 2-CdA+IDA and 2-CdA alone (median 9.5% at 24 h and 23.5% at 48 h; P=0.0013 and 0.0207, respectively). In conclusion; these data indicate an additive cytotoxic effect on B-CLL cells of DOX, MIT, and IDA applied in vitro with 2-CdA; all of them induced apoptosis with similar efficacy. We suggest that further preclinical and clinical studies concerning combined use of 2-CdA with anthracyclines are desirable. High sensitivity of B-CLL cells to IDA suggests the possibility of lowering its dose in patients, especially when combined with 2-CdA.

Anthracyclines potentiate activity against murine leukemias L1210 and P388 in vivo and in vitro

The interactions of 2-chlorodeoxyadenosine (2-CdA, cladribine) and three anthracyclines: doxorubicin (DOX), idarubicin (IDA) and mitoxantrone (MIT) were evaluated on murine leukemias P388 and L1210. Prolongation of survival time of animals receiving drugs in combination compared to mice treated with drugs in monotherapy was tested. We have also evaluated interactions of the cytostatics on murine leukemias in vitro by measuring their inhibitory effects on P388 and L1210 cell proliferation. We have observed a synergistic effect of MIT and IDA in combination with 2-CdA on P388 leukemia resulting in an increase of life span (ILS)=226% in case of MIT+2-CdA and ILS=126% in the case of IDA+2-CdA, whereas 2-CdA used as a sole drug resulted in an ILS=47%. The survival time of animals inoculated with P388 leukemic cells and treated with DOX+ 2-CdA was similar to ILS gained by DOX monotherapy (178% and 200% respectively). The mice bearing L1210 leukemia receiving combined chemotherapy lived significantly longer than the animals on single agent regimens. The animals treated with schedule 2-CdA+MIT lived significantly longer (P=0.004) as compared to the groups receiving drugs in monotherapy (ILS of 2-CdA+MIT group=60%, ILS of MIT group 33%, and 2-CdA group 33%). Finally, combination of DOX or IDA with 2-CdA resulted in ILS =73% (2-CdA+DOX regimen), and ILS=60% in case of 2-CdA+IDA regimen, which is significantly higher than ILS gained on monotherapy schedules. In vitro tests revealed that all tested anthracyclines enhance the antiproliferative activity of 2-CdA against L1210 and P388 leukemic cells (P<0.05). Our study has shown that all anthracyclines potentiate 2-CdA antileukemic activity, both in vivo and in vitro. It failed however to point the best one to be combined with cladribine. We suggests that further clinical trials with such combinations are needed.