Combination of granulocyte colony-stimulating factor and low-dose cytosine arabinoside further enhances myeloid differentiation in leukemia cells in vitro

Efficacy of high-dose cytarabine and aclarubicin in combination with G-CSF regimen compared to intermediate/high-dose cytarabine and standard-dose cytarabine induction regimen for non-remission acute myeloid leukemia

BACKGROUND

Acute myeloid leukemia (AML) patients with non-remission (NR) after the first cycle of standard induction chemotherapy remain a challenge owing to poor response and tolerance to re-induction regimen. We retrospectively evaluated the efficacy and safety of three regimens in AML patients refractory to the first course of standard induction regimen.

MATERIALS AND METHODS

The three regimens consisted of (1) High-dose cytarabine, aclarubicin and granulocyte colony-stimulating factor (HD-CAG) regimen (n = 44); (2) intermediate/high-dose cytarabine (I/HDAC) regimen (n = 30); and (3) standard-dose cytarabine (SDAC) combination regimen that was identical to the first course of standard induction regimen (n = 27).

RESULTS

Results indicated that after the second course, the overall response (OR), i.e., complete remission [CR]+partial remission [PR]) rates in HD-CAG was higher than in the I/HDAC group (84.1% vs. 56.7%, P = 0.009), whereas the CR rates among 3 groups were not statistically different (P = 0.541). Meanwhile, the proportion of subjects reporting certain adverse effects in the HD-CAG group was lower than the I/HDAC or SDAC groups. There were no significant differences in overall survival (OS) and disease-free survival (DFS) rates among the 3 groups (P = 0.881 and P = 0.872, respectively).

CONCLUSION

Our preliminary results indicate that HD-CAG regimen may represent a better alternative option for AML patients with NR after the first course of standard induction chemotherapy.

Efficacy of cytarabine, aclarubicin and granulocyte colony-stimulating factor (CAG) regimen compared to FLAG regimen for adult patients with relapsed/refractory Philadelphia chromosome-negative acute lymphoblastic leukemia

In this study, we retrospectively assess the results in comparing the efficacies and toxicities of the three chemotherapy regimens: CAG (cytarabine, aclarubicin and granulocyte colony-stimulating factor (G-CSF), n=87), HD-CAG (increasing the dose of aclarubicin in CAG regimen, n=73), and FLAG (fludarabine, cytarabine and G-CSF, n=41) regimens in patients with relapsed/refractory Philadelphia chromosome-negative acute lymphoblastic leukemia (Ph--ALL). Our study indicated that after one therapy course, the overall response (OR, complete reimssion (CR)+partial remission (PR)) rate was higher in CAG than that in FLAG regimen (55.2% vs. 31.7%, P=0.013), while the CR (50.7% vs. 26.8%, P =0.013) and OR (64.4% vs. 31.7%, P=0.001) rates in HD-CAG regimen were both higher than that in FLAG regimen. Furthermore, the results were more pronounced in the subgroup of patients with T cell and refractory Ph--ALL. There were no significant differences in CR and OR rates between the CAG and HD-CAG regimens. Meanwhile, the adverse effects of CAG regimen were less toxic than the FLAG and HD-CAG regimens. There were no statistically significant differences in overall survival rates at two years among the three groups (FLAG: 9.8%±4.6%, CAG: 11.8%±4.5%, HD-CAG: 11.1%±4.0%; P>0.05). Our preliminary results indicated that CAG and HD-CAG regimens could be more effective and safer than FLAG regimen for relapsed/refractory Ph--ALL.

Increasing the dose of aclarubicin in low-dose cytarabine and aclarubicin in combination with granulocyte colony-stimulating factor (CAG regimen) can safely and effectively treat relapsed or refractory acute myeloid leukemia

It is difficult for relapsed and refractory acute myeloid leukemia (AML) patients to achieve complete remission (CR). The CAG regimen [low-dose cytarabine and aclarubicin in combination with granulocyte colony-stimulating factor (G-CSF)] has been used to treat relapsed and refractory AML patients, and showed good therapeutic efficacy. It is unknown, however, whether increasing the dose of aclarubicin in CAG regimen could treat relapsed or refractory AML safely and effectively. We evaluate the efficacy and tolerability of increasing the dose of aclarubicin in CAG regimen, in 37 relapsed or refractory AML patients. All patients were treated with CAG regimen including low-dose cytarabine (10 mg/m(2) every 12 h, days 1-14), aclarubicin (5-7 mg/m(2) every day, days 1-14), and G-CSF (200 μg/m(2) every day, days 1-14) priming. After a single course of therapy, the overall response [CR + partial remission (PR)] rate of all patients was 78.4 % (29/37), in which the CR rate was 62.2 % (23/37). There was no early death. The median overall survival was 6 months (range 2-36 months). Myelosuppression was ubiquitous, but tolerated. No severe non-hematologic toxicity was observed. Thus, increasing the dose of aclarubicin in CAG regimen can be used safely and effectively in the treatment of relapsed or refractory AML.

Cell cycle-dependent priming action of granulocyte colony-stimulating factor (G-CSF) enhances in vitro apoptosis induction by cytarabine and etoposide in leukemia cell lines

We investigated the priming effect and mechanism of granulocyte colony-stimulating factor (G-CSF) in chemotherapy with low-dose Ara-C and VP-16 for acute myeloid leukemia. We analyzed cell proliferation, apoptosis, and cell cycle in vitro using leukemia cell lines 32Dcl3, U937, HL-60, and Ba/F3. Cell proliferation assays were performed using the Trypan Blue dye exclusion method. For detection of apoptosis, the Annexin V-binding capacity of treated cells was examined by flow cytometry. To evaluate the cell cycle, we used an FITC BrdU Flow kit and conducted analysis by flow cytometry. The combination of Ara-C and VP-16 significantly enhanced the observed effects compared with those of Ara-C or VP-16 alone. Concurrent administration of G-CSF further reduced the cell number and viability of 32Dcl3 and U937 cells, but not of HL-60 and Ba/F3 cells. Apoptotic cells were significantly increased in number by the addition of G-CSF to 32Dcl3 and U937 cells, while G-CSF had no significant effect on HL-60 and Ba/F3 cell lines. The addition of G-CSF significantly decreased the percentage of G0/G1-phase cells and significantly increased that of S-phase cells among 32Dcl3 and U937 cells. No significant effect was observed for HL-60 and Ba/F3 cells. An enhancement was confirmed for the combination of Ara-C, VP-16, and G-CSF for 32Dcl3 and U937 cells but not for HL-60 and Ba/F3 cells. It was thought that this difference was a result of different responses to G-CSF. G-CSF potentiates Ara-C- and VP-16-induced cytotoxicities through apoptosis induction by mobilizing resting G0-G1-phase cells into S phase.

Continuous drip infusion of low dose cytarabine and etoposide with granulocyte colony-stimulating factor for elderly patients with acute myeloid leukaemia ineligible for intensive chemotherapy

BACKGROUNDS AND OBJECTIVES

The optimal strategy for the management of elderly patients with acute myeloid leukaemia (AML) is still controversial. We previously reported the effectiveness of low dose cytarabine (Ara-C) and etoposide (VP-16) (AV therapy) for those elderly AML patients ineligible for intensive chemotherapy. We initiated the present feasibility study to improve the efficacy by using glanulocyte-colony stimulating factor (G-CSF) with AV therapy (AVG therapy).

PATIENTS AND METHODS

The eligibility for enrolment was AML patients according to the World Health Organization (WHO) criteria who were over 60 years of age and who had difficulty in tolerating intensive chemotherapy due to their poor performance status (PS) or some comorbidities. They were given continuous drip infusion of Ara-C (20 mg/body) and VP-16 (50 mg/body) for 7-14 days, and were also simultaneously administered G-CSF (150 microg/m2) once daily.

RESULTS

The median age of consecutively enrolled 25 patients was 73 years. Eighteen (72%) patients achieved complete remission (CR). The 1-year overall survival (OS) and the 3-year OS rates were 69% and 22%, respectively. The 1-year disease free survival (DFS) rate in CR patients was 44%. The major regimen related toxicities of grade 3 or 4 were only febrile neutropenia in 15 patients (60%). No regimen-related mortality was observed.

CONCLUSION

AVG therapy was therefore found to be an effective and well-tolerated regimen for remission induction in elderly AML patients with poor PS or comorbidity.

CAG regimen enables relapsed or refractory T-cell acute lymphocytic leukemia patients to achieve complete remission: a report of six cases

Patients with either relapsed or refractory T-cell acute lymphocytic leukemia (T-ALL) are candidates for allogeneic hematopoietic stem cell transplantation (allo-HSCT). Achieving complete remission (CR) in these patients is difficult but crucial for the success of allo-HSCT. In this study, we examined 6 relapsed or refractory T-ALL patients. In the patient group, 4 were male and 2 were female, with ages ranging from 15 to 57 years (median=29 years). All 6 patients presented with the nonmature T-ALL phenotype. Cytogenetically, only one had an i(7q) anomaly, whereas the remaining 5 cases had normal karyotypes. One of these patients had the MLL/AF9 fusion transcript, as shown by molecular study. After initial remission-induction therapy, two patients achieved CR, one showed a partial remission, and all relapsed soon. The other 3 cases failed the therapy. The CAG regimen (cytosine arabinoside 10 mg/m(2) subcutaneously every 12 hr, day 1-14; aclarubicin 5-7 mg/m(2) intravenously daily, day 1-8; and concurrent use of G-CSF 200 microg/m(2)/day subcutaneously) was devised originally for the treatment of relapsed acute myelogenous leukemia. After CAG therapy, all the T-ALL patients in our study achieved CR, indicating that the CAG regimen is beneficial to the treatment of relapsed or refractory T-ALL. The efficacy of CR-induction in T-ALL patients and the adverse effects of the CAG regimen need to be further studied.

Cytokines in the differentiation therapy of leukemia: from laboratory investigations to clinical applications

Differentiation therapy of leukemia is the treatment of leukemia cells with biological or chemical agents that induce the terminal differentiation of the cancer cells. It is regarded as a novel and targeted approach to leukemia treatment, based on our better understanding of the hematopoietic process and the mechanisms of its deregulation during leukemogenesis. Clinically, differentiation therapy has been most successful in acute promyelocytic leukemia using all-trans-retinoic acid as the inducer, either alone or in combination with chemotherapy. This review presents evidence that a number of hematopoietic cytokines play important roles in both normal and aberrant hematopoietic processes. In vitro laboratory investigations in the past two decades using well-characterized myeloid leukemic cell lines and primary blast cells from leukemia patients have revealed that many hematopoietic cytokines can trigger lineage-specific differentiation of leukemia cells, which may have important implications in the clinical setting. Moreover, our current understanding of cytokine interactions and the molecular mechanisms of cytokine-induced leukemic cell differentiation will be discussed in the light of recent findings. Finally, ways in which laboratory research on cytokines in the differentiation therapy of leukemia can lead to the improved design of protocols for future clinical applications to leukemia therapy will also be addressed.

Combination of 22-oxa-1,25-dihydroxyvitamin D(3), a vitamin D(3) derivative, with vitamin K(2) (VK2) synergistically enhances cell differentiation but suppresses VK2-inducing apoptosis in HL-60 cells

We originally reported that vitamin K(2) (VK2) effectively induces apoptosis in various types of primary cultured leukemia cells and leukemia cell lines in vitro. In addition, VK2 was shown to induce differentiation of leukemia cells when the cells were resistant against VK2-inducing apoptosis. A novel synthetic vitamin D(3)derivative, 22-oxa-1,25-dihydroxyvitamin D(3) (OCT: oxacarcitriol) shows a more potent differentiation-inducing ability among myeloid leukemia cells in vitro with much lesser extent of the induction of hypercalcemia in vivo as compared to the effects of 1alpha,25(OH)(2)D(3). In the present study, we focused on the effects of a combination of OCT plus VK2 on leukemia cells. Treatment of HL-60 cells with OCT for 72 h induces monocytic differentiation. A combination of OCT plus VK2 dramatically enhances monocytic differentiation as assessed by morphologic features, positivity for non-specific esterase staining, and cell surface antigen expressions. This combined effect far exceeds the maximum differentiation induction ability at the optimal concentrations of either OCT or VK2 alone. In addition, pronounced accumulation of the cells in the G0/G1 phase is observed by combined treatment with OCT plus VK2 as compared with each vitamin alone. In contrast to cell differentiation, caspase-3 activation and apoptosis induction in response to VK2 are significantly suppressed in the presence of OCT in HL-60 cells. These data suggest that monocytic differentiation and apoptosis induction of HL-60 cells are inversely regulated. Furthermore, pronounced induction of differentiation by combined treatment with VK2 plus OCT was also observed in four out of six cases of primary cultured acute myeloid leukemia cells in vitro, suggesting that VK2 plus OCT might be a potent combination for the differentiation-based therapy for acute myeloid leukemias.

Apoptosis/differentiation-inducing effects of vitamin K2 on HL-60 cells: dichotomous nature of vitamin K2 in leukemia cells

We originally reported that vitamin K2 (VK2) analogs, including menaquinone 4 (MK4) but not vitamin K1, effectively induce apoptosis in various types of primary cultured leukemia cells and leukemia cell lines in vitro. It has also been reported by others that VK2 showed the differentiation-inducing activity in leukemia cell lines. To investigate the discrepancy between apoptosis- and differentiation-inductions of leukemia cells by VK2 treatment, we used bcl-2 gene transfected HL-60 cells (HL-60-bcl-2) which resulted in five-fold over-expression of BCL-2 protein, and then compared the effects of MK4 to the control HL-60-neo cells. Seventy-two hours of exposure to various concentrations of MK4 resulted in growth inhibition of these cells in a dose-dependent manner (0.1-50 microM), however, HL-60-bcl-2 was less sensitive against MK4. MK4 potently induced apoptosis of HL-60-neo cells along with the depolarization of mitochondrial membrane potential and caspase-3 activation. Notably, HL-60-bcl-2 was almost completely resistant to apoptosis induction in response to MK4, although cell growth inhibition was still observed. In spite of the abrogation of apoptosis induction, about 90% of HL-60-bcl-2 cells were arrested in the G0/G1 phase within 48 h of exposure to 10 microM of MK4 accompanied by up-modulation of p27KIP1 expression. Concomitantly, HL-60-bcl-2 cells underwent monocytic differentiation. These data suggest that VK2 also shows the differentiation inducing effects on leukemia cells which are resistant against VK2-inducing apoptosis. The dichotomous nature of VK2 against leukemia cells appears to have clinical benefits for the treatment of patients with leukemias and myelodysplastic syndromes.