Treatment of relapsed acute myeloid leukemia using GM-CSF before intensive chemotherapy

In vitro effects of growth factors and interferon-alpha on busulfan cytotoxicity

An experimental approach to increasing the effectiveness of leukemia treatment with S-phase-specific cytotoxics is to increase the cycling of leukemia cells with growth factors. However, growth factors may have a different relationship with non-cell-cycle-specific agents. The authors examined the effects of granulocyte colony-stimulating factor (G-CSF), granulocyte/macrophage colony-stimulating factor (GM-CSF), and interferon-alpha (INF-alpha) on the cytotoxic effects of the alkylating agent busulfan on the erythro-myeloid cell line K562. G-CSF and GM-CSF increased the proliferation and colony-forming ability of K562 cells and protected the cells from busulfan effects. INF-alpha decreased the colony-forming ability and proliferation of the K562 cells and demonstrated a possibly additive effect with busulfan. In the cell line K562, the growth factors G-CSF and GM-CSF protected the cells from the non-cell-cycle-specific alkylating agent busulfan, whereas IFN-alpha demonstrated an additive cytotoxic effect.

The treatment of acute myeloid leukemia in first relapse: a comprehensive review of the literature

Twenty years of published literature was reviewed for chemotherapy regimens used to treat patients with acute myeloid leukemia (AML) in first relapse. Thirty-one trials containing at least 20 patients in first relapse and information on patient age, duration of first complete remission (CR1), and rate of second complete remission (CR2) were analyzed. These trials included 10 retrospective studies with CR2 rates ranging from 30 to 64%, two phase II single-agent studies with CR2 rates of 8 and 25%, 15 phase II combination-agent studies with CR2 rates ranging from 14 to 87%, and four phase III randomized studies with CR2 rates ranging from 40 to 89%. When reported, median duration of CR2 was < or = 14 months and overall median survival was < or = 12 months. The probability of 3-year survival ranged from 8 to 29%. Combination therapies resulted in higher CR2 rates but were associated with longer duration of myelosuppression and greater incidence of mucositis. None of the reviewed regimens provided durable remissions for the majority of AML patients in first relapse. The CR2 rates were closely associated with age and duration of CR1. Therefore, considering the poor clinical outcomes of patients with AML in first relapse, improved therapies need to be developed.

Timed sequential chemotherapy with concomitant granulocyte colony-stimulating factor for high-risk acute myelogenous leukemia: a single arm clinical trial

BACKGROUND

The timed-sequential chemotherapy regimen consisting of etoposide, mitoxantrone and cytarabine (EMA) is an effective therapy for relapsed or refractory acute myelogenous leukemia (AML). We postulated that granulocyte colony-stimulating factor (G-CSF) might enhance the cytotoxicity of EMA by increasing the proportion of leukemic blasts in S-phase. We added G-CSF to EMA (EMA-G) for therapy of advanced high-risk AML patients.

METHODS

High-risk AML was defined as refractory, relapsed or secondary to either an antecedent hematologic disorder or exposure to cytotoxic agents. The patients were treated with one course of EMA-G consisting of mitoxantrone and cytarabine on days 1-3, and etoposide and cytarabine on days 8-10. G-CSF was started on day 4 and continued until absolute neutrophil count recovered.

RESULTS

Thirty patients were enrolled. The median age was 51 years (range, 25-75). Seventeen (61%) patients had unfavorable cytogenetic karyotypes. Twenty (69%) patients had secondary AML. Ten (34%) had relapsed disease. Four (14%) had refractory AML. Three (10%) patients died from febrile neutropenia and sepsis. Major non-hematologic toxicity included hyperbilirubimenia, renal insufficiency, mucositis, diarrhea, nausea and vomiting, skin rash. A complete remission was achieved in 13 (46%) patients. Median overall survival was 9 months (range, 0.5-66). Median relapse-free survival (RFS) for those who had a CR was 3 months (range, 0.5-63) with RFS censored at the time of allogeneic bone marrow transplantation or peripheral stem cell transplantation for 6 of the patients.

CONCLUSIONS

EMA-G is a safe and efficacious option for induction chemotherapy in advanced, high-risk AML patients. The activity of EMA may be increased if applied in patients with less advanced disease.

Kinetic characteristics of de novo and secondary AML cells influence their response to haemopoietic growth factor (HGF) priming and correlate with clinical outcome

This study has assessed the effect of in vitro haemopoietic growth factor (HGF) priming on the S phase activity of cells from patients with de novo AML and AML secondary to MDS. The occurrence of receptors for G-CSF, GM-CSF, IL-3 and SCF on marrow cells was assessed using immunofluorescent ligand binding assays. Additionally, patients responses to first phase induction chemotherapy was recorded to examine whether in vitro kinetic data might correlate with clinical outcome. All kinetic and receptor assays were performed in normal marrow cells to ascertain their response to priming. Incubation of AML cells in serum free medium (SFM) +/- G + GM-CSF, IL-3, SCF, G + GM-CSF + SCF or IL-3 + SCF prior to S phase assessment revealed that priming permutations inclusive of SCF were most effective but also that the baseline level of S phase activity with SFM alone influenced the subsequent response to priming. Regardless of AML group, samples with low baseline S phase activity (< 10%) were significantly more responsive than those with high (> 10%) SFM S phase levels. However there was no corresponding difference in the percentages of cells bearing receptors. In both AML groups, low baseline S phase activity was observed more frequently in samples from patients who achieved CR. Normal samples possessed receptors for all HGFs and were responsive to all priming permutations except SCF alone. This study raises four points: (a) it may be prudent to reserve the use of priming HGFs for those patients with low baseline S phase activity whose cells respond in vitro and to use SCF in these priming cocktails; (b) the presence of receptors capable of ligand binding in AML samples did not guarantee kinetic response; (c) normal progenitors were responsive to priming which may have implications for haemopoietic reconstitution post therapy; and (d) the kinetic characteristics of AML progenitors may influence clinical outcome regardless of whether treatment includes HGFs.

Haemopoietic growth factors, the cell cycle of acute myeloblastic leukaemia progenitors and sensitivity to cytosine arabinoside

We describe an 'in vitro' model which permits assessment of acute myeloblastic leukaemia (AML) progenitor cells' response to Ara-C alone and in conjunction with recombinant human (rh) cytokines by evaluating cell cycle characteristics of purified AML blast progenitors and their chemosensitivity in clonogenic culture before and after cytokine priming. Parallel investigation of Ara-C/cytokine treatment on normal CFU-GM progenitors was included as these cells are important for post-therapeutic reconstitution of haemopoiesis. Kinetic and clonogenic findings for AML marrows were extremely variable with G+GM-CSF or IL-3 priming. However, inclusion of rhSCF and resultant synergism with the other cytokines, introduced a pronounced element of consistency in AML results. Normal CFU-GM responded to rhG+GM-CSF or IL-3 with increased kinetic activity and sensitivity to Ara-C. rhSCF synergised strongly with the other factors, causing increased cell cycling and attainment of maximal chemosensitivity 'in vitro'. No correlation was evident between 'in vitro' findings for AML samples, patient FAB types or clinical outcome. This study highlights the fact that both normal and AML cells can be targeted by rh cytokines, particularly when rhSCF is included in priming cocktails.

Influence of rhGM-CSF on Ara-C sensitivity of patients with acute myeloid leukemia in relapse: a flow cytometry study

Twenty-three patients with acute myelogenous leukemia (AML) in first relapse were treated with high-dose cytosine-arabinoside (Ara-C) and amsacrine or idarubicin. To prime the cells, the patients were given rhGM-CSF. We studied the influence of 48-h infusion of rhGM-CSF on proliferation and Ara-C sensitivity of leukemic cells both ex vivo and in vitro. We found that a 48-h infusion of rhGM-CSF increased both white blood cell counts and peripheral blood blast cell percentages. Using a Bromodeoxyuridine/DNA (BrdUrd/DNA) staining in flow cytometry, we found an non-constant increase in cells in the S-phase. Ex vivo 48-h culture of leukemic cells with or without rhGM-CSF, with or without other hematopoietic growth factors (HGFs), showed a greater increase of the cells in the S-phase with GF but no correlation with the ex vivo results. We used a method of quantitation of the DNA synthesis previously described (Lacombe F., et al. (1992) Cytometry 13, 730) to monitor the Ara-C sensitivity of the cells in S-phase before and after 48-h infusion with rhGM-CSF. We observed a great variation in the Ara-C sensitivity of the leukemic cells before and after infusion with rhGM-CSF from one patient to another. The BrdUrd/DNA method seems a convenient method to study the influence of HGFs on Ara-C sensitivity of the patients.

High-dose cytarabine and recombinant human granulocyte colony-stimulating factor for the treatment of resistant acute myelogenous leukemia

Few salvage treatments are successful for patients with relapsed acute myelogenous leukemia after a short first remission, multiple relapses, or for patients with disease refractory to initial induction chemotherapy. To improve the results of salvage therapy we studied the efficacy and toxicity of a combination of G-CSF (5 mu tg/kg IV q day) used as a priming agent followed by continued exposure to G-CSF and high-dose cyatarabine (2 gm/m(2) IV q 12 hours x 12 doses) in fifteen adult patients with relapsed or refractory acute myelogenous leukemia. Nine of fourteen (64%; 95% confidence interval 35 to 87%) achieved complete remission, four failed to enter remission and one died of multiorgan system failure after progressive leukemia cutis despite chemotherapy-induced bone marrow aplasia. Median disease-free survival is 148 days and median survival from study entry for responding patient is 174 days. Three patients who achieved complete remission subsequently relapsed with a median time to relapse of 147 days. Median time to granulocyte >0.5 x 10(9)/L was 22 days (19 to 34 days) and the median time to platelet recovery >20 x 10(9)/L was 30 days (23 to 214 days). Although gastrointestinal toxicity was common, no patient developed severe cardiac, hepatic, pulmonary, or neurologic complications. An elevation in the percent of bone marrow blasts in S-phase after 48 hours of treatment with G-CSF was identified in 7 of 12 evaluable patients. These results demonstrate that the combination of G-CSF and high-dose cytarabine may be used as an effective salvage treatment for patients with resistant acute myelogenous leukemia.

The effect of haemopoietic growth factors on the cell cycle of AML progenitors and their sensitivity to cytosine arabinoside in vitro

This study examines the effect of pretreatment in liquid culture of acute myeloid leukaemic (AML) progenitors with recombinant human IL-3 or G and GM-CSF. Prior to and following cytokine priming, the sensitivity of cells to cytosine arabinoside (Ara-C) at concentrations ranging from 10(-12) to 10(-4) M was assessed in clonogenic culture. In addition, the initial percentage of AML cells in S phase was assessed and their subsequent kinetic response to cytokine treatment evaluated by FACScan analysis. Light-density marrow cells (LDMCs) from 19 AML patients were initially T-cell and monocyte depleted in order to remove potential sources of endogenous cytokine production prior to in vitro investigation. LDMCs were incubated in liquid phase for 7 d in a chemically defined complete medium with or without cytokines. Clonogenic data from fresh AML LDMCs not pretreated with growth factors demonstrated a heterogenous response to Ara-C. In only 4/15 marrows tested clonogenically was there any improvement in sensitivity to Ara-C following cytokine priming. S-phase data on all 19 marrows were similarly variable either before or after cytokine preincubation. There was no discernible correlation between clonogenic and kinetic data, nor could any relationship be established between in vitro findings and the FAB subtypes of patients or clinical outcomes. In summary, it would appear that the cell-cycle status of AML cells is likely to be only one of many contributory factors governing the sensitivity of AML progenitors to Ara-C. The clinical response of AML patients to cytokine therapy in association with cell-cycle-specific cytotoxic agents may therefore be variable and unpredictable.