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In acute lymphoblastic leukemia (ALL), treatment with granulocyte colony stimulating factor (G-CSF) during remission induction shortens granulocytopenia and may decrease morbidity due to infections. However, the optimal timing of G-CSF administration after chemotherapy is not known. In a prospective randomized multi-center study, adult ALL patients were treated with high-dose ARA-C [HDAC, 3 g/m(2) bid (1 g/m(2) bid for T-ALL) days 1-4] and mitoxantrone (MI 10 mg/m(2) days 3-5). They were randomized to receive recombinant human G-CSF (Lenograstim) 263 micro g/day SC starting either from day 12 (Group 1) or day 17 (Group 2). Fifty-five patients (41 male, 14 female) with a median age of 34 years (range: 18-55 years) were enrolled into the study; 50 patients were evaluable. The median duration of neutropenia <500/ micro l after HDAC/MI was 12 days (range: 7-22 days) in the early G-CSF Group 1 and also 12 days (range: 4-22 days) in the late G-CSF Group 2; this was shorter than in the historical control group (15 days, range: 4-43 days, n=46) where the patients received identical cytotoxic treatment without G-CSF. Seventeen infections were observed in 14 patients in Group 1 (47%) and 13 infections in 10 patients in Group 2 (50%) compared to 27 infections in 49 patients of the historical control (54%). In Group 1, the patients received a median of 11 injections with G-CSF (range: 7-22) compared to 7 injections (range: 4-19) in Group 2. The total administered dose of G-CSF in Group 2 was significantly reduced by 40% ( P<0.0001). The delayed start of G-CSF after HDAC/MI in ALL achieves the same clinical benefit compared to the earlier initiation of G-CSF. The reduction of treatment costs by reducing the total G-CSF dose may be important in future treatment with this hematopoietic growth factor.

Used as single agents, ATRA, G-CSF, and IFN-alpha have shown a moderate benefit in patients with low-risk MDS, with a response rate of 10%. The aim of the present study was to evaluate the efficacy of a combination of these agents. The effect on hemoglobin (Hb), platelets, and absolute neutrophil count (ANC), as well as on transfusion frequency, was examined in 25 patients with MDS (11 RA, four RARS, eight RAEB, two CMML). The median age was 61 years (range 44-81), and the male/female ratio was 14/11. Treatment consisted of ATRA at 25 mg/m2/day p.o. for months 1, 3, 5, 7, 9, and 11, IFN-alpha at 1.5 MIU twice a week s.c. for 52 weeks, and, in patients with initial ANC <500/microl, G-CSF at 100-480 microg daily s.c. according to the degree of ANC. The duration of therapy was scheduled for 12 months. Two patients achieved ongoing CR (+19 months; +16 months), one patient with RA after 3 months and one with CMML after 7 months of treatment. In all patients, the mean ANC increased significantly from 1400+/-200/microl before the start of therapy to 3500+/-600/microl at the end of treatment (p=0.025). In two patients an increase of Hb was observed, and one patient ceased to require transfusions. In an additional patient with RA and 5q-syndrome, the platelet count normalized following administration of ATRA/IFN-alpha, increasing from 89,000/microl to 293,000/microl. The eight RAEB patients were nonresponders. We conclude that therapy with ATRA, IFNalpha, and G-CSF is effective in approximately 35% of low-risk MDS patients (in this study: six of 17) and may induce complete remission in individual cases.

Differentiation induction therapy is being tested in myelodysplastic syndromes to ameliorate maturation defects and to restore normal hematopoietic function. To this end, 17 patients (eight with refractory anemia, two with refractory anemia and ring sideroblasts, and seven with refractory anemia and excess of blast cells) were treated with a combination of all-trans-retinoic acid (ATRA), granulocyte colony-stimulating factor (G-CSF), erythropoietin (EPO), and alpha-tocopherol for durations of 8-16 weeks. Absolute neutrophil counts increased in all patients; platelet counts increased in five patients with discontinuation of transfusion needs in two of four transfusion-dependent patients. Stimulation of erythropoiesis was seen in eight patients with an increase in hemoglobin concentration in three, a discontinuation of transfusion requirements in another three, and a significant increase in reticulocyte counts as the only parameter in two patients. Clinically important multilineage responses with increases of hemoglobin levels or discontinuation of transfusion needs were thus seen in six patients (35.3%) with three patients having a trilineage response. Serum erythropoietin concentrations did not differ significantly between responders and nonresponders, but the erythroid response was accompanied by a rise in the serum transferrin receptor levels. In the bone marrow, the myeloid-to-erythroid ratio and the maturation index of myeloid cells increased during therapy, while the percentage of blast cells did not change. Cytogenetic analysis demonstrated the persistence of the abnormal clones. Prior to therapy, nonresponders had a significantly higher serum TNF level than responders. Serum concentrations of TNF-alpha and soluble TNF-alpha receptor significantly increased during therapy, but mainly in the patients without an erythroid and platelet response. Soluble IL-2 receptor and soluble ICAM-1 concentrations both increased. This pilot study demonstrates that treatment with ATRA/G-CSF/EPO/tocopherol is well tolerated, leading to normalization of neutrophil counts in most, and to improvement of platelets and red blood cells in a significant subgroup of patients.

Hematopoietic growth factors primarily used in patients with acute myelogenous leukemia after chemotherapy could reduce significantly the neutrophil recovery time in all patients. In high-risk acute myelogenous leukemia, trials also reported a reduction in the incidence of documented infections and early mortality rate. Thus in elderly patients with acute myelogenous leukemia and in high-risk patients with acute myelogenous leukemia the use of hematopoietic growth factors seems justified. Whether the rate of infections, particularly of life-threatening fungal infections, can be reduced by granulocyte colony-stimulating factor or granulocyte-macrophage colony-stimulating factor after chemotherapy cannot be known without larger studies. A novel strategy in the treatment of acute myelogenous leukemia is the attempt to increase the growth fraction of clonal leukemic cells prior to administration of chemotherapeutic agents by the administration of hematopoietic growth factors. Evidence shows that hematopoietic growth factors enhance anti-leukemic activity of cytosine arabinoside against leukemic cells by recruitment of leukemic cells into cell cycle, an increase of intracellular cytosine arabinoside triphosphate:deoxcytidine 5' triphosphate pool ratios, or by an enhanced cytosine arabinoside incorporation into the DNA of acute myelogenous leukemia blasts. Whether these mechanisms lead to an increase in the complete remission rate and eventually to an improvement in survival must be answered in ongoing larger acute myelogenous leukemia trials using granulocyte colony-stimulating factor or granulocyte-macrophage colony-stimulating factor in such a setting.

Since all-trans retinoic acid (ATRA) and granulocyte colony-stimulating factor (G-CSF) not only enhance proliferation and differentiation of normal myeloid cells but also synergistically promote the differentiation of myeloid leukemic blast cells in vitro, we have started a pilot study of combined treatment with ATRA and G-CSF in patients with myelodysplastic syndrome, to analyze the effect of these drugs on hematopoietic differentiation. ATRA was given at 45 mg/m2/day p.o. from week 1-12 and G-CSF at 5 micrograms/kg/day s.c. from week 5-12 with dose modifications according to the absolute neutrophil counts (ANC). A total of 15 patients, predominantly with refractory anemia, were treated. During initial ATRA therapy, a bilineage response with increases of both ANC and platelet counts occurred in three patients. During combined ATRA/G-CSF therapy, ANC increased in all patients, and platelets increased in three out of 14 evaluable patients. An increase in hemoglobin concentration and a decrease in transfusion requirements occurred in one patient each. In the bone marrow, the myeloid-to-erythroid ratio increased during ATRA treatment and remained increased during concomitant G-CSF administration, while the maturation index of myeloid cells increased only in response to ATRA therapy, but returned to baseline during ATRA/G-CSF treatment. Cytogenetic analysis demonstrated persistence of the abnormal clones in all patients. The number of circulating progenitor cells CFU-GM increased in all patients studied. Serum concentrations of the soluble TNF receptor and IL-2 receptor both increased, while TNF-alpha--already elevated prior to therapy--and soluble ICAM-1 concentrations did not significantly change. Adverse effects included dermatitis and cheilosis in most patients, and a drop in platelet counts related to G-CSF in one patient. The pilot study demonstrates that the combination treatment with ATRA/G-CSF is well tolerated, leading to normalization of ANC in most, and improvement of platelets and red blood cells in a subgroup of patients.