Modeling the Pharmacodynamics of Highly Schedule-Dependent Agents: Exemplified by Cytarabine-Based Regimens in Acute Myeloid Leukemia

A network meta-analysis of randomized controlled trials of induction treatments in acute myeloid leukemia in the elderly

BACKGROUND

The optimal induction treatment of acute myeloid leukemia (AML) in the clinically and biologically heterogeneous group of elderly patients is not well-defined since direct comparisons between treatments is limited.

OBJECTIVE

The aim of this study was to estimate the relative effectiveness of induction treatments in AML elderly patients.

METHODS

A network of multiple treatments meta-analysis was performed by combining direct and indirect evidence from published randomized controlled trials (RCTs). The complete remission (CR) was considered as the outcome of interest. We systematically searched PubMed, EMBASE, and Cochrane Library until September 30, 2010, to identify all RCTs published in English that compared diverse induction chemotherapies in elderly AML patients. Our search strategy focused on RCTs that included AML patients >60 years, considering, however, that age stratification was varied between countries and over time and studies were not necessarily designed to compare elderly patients. Regimens were grouped a priori into 42 different types of induction treatment. Prognostic parameters (age, performance status, unfavorable cytogenetics, antecedent malignancy), AML outcomes (median disease-free, overall survival, CR, induction deaths), and myelotoxicity parameters (median duration until neutrophil recovery [>1.0 × 10(9)/L], platelet recovery [>100 × 10(9)/L], hospitalization duration) were evaluated for each induction type. In combining direct and indirect evidence, we calculated the odds ratio (OR) for each therapy relative to the most commonly used combination of standard-dose daunorubicin (30-60 mg/m(2) for 3 days) and standard-dose cytarabine (100 mg/m(2) for 7-10 days) that was set as the reference induction treatment.

RESULTS

We identified 65 RCTs (15,110 patients) that described 64 direct comparisons of induction treatments, but only 14 of them showed significant differences in CR after random effects meta-analyses. Median age of included patients was 68, 18.0% had secondary AML, 21.1 % had poor performance status, 26.7% displayed unfavorable cytogenetics, and 49.3% finally achieved CR. No significant differences were observed in the recorded induction toxicity parameters among the treatment arms. Through the network meta-analysis, the addition of all-trans retinoic acids or lomustine to the combination of idarubicin plus cytarabine showed significantly higher CR rate (OR = 1.93 [1.06-3.49] and 1.76 [1.08-2.88], respectively), whereas no treatment, clofarabine, daunorubicin plus topotecan, and the 2 different schedules of gemtuzumab ozogamicin (at 1, 3, and 5 days and at 1 and 8 days) showed a significantly lower CR rate (OR = 0.01 [0.001-0.19], 0.15 [0.04-0.58], 0.03 [0.002-0.64], 0.06 [0.01-0.51], and 0.05 [0.01-0.32], respectively) than that of the reference induction. Median overall survival showed no difference between treatments (P = 0.150) but was significantly increased during the last 30 years (P < 0.001), presumably reflecting advances in AML management.

CONCLUSIONS

Compared with the reference induction, significant differences were found for specific induction regimens, although most compared regimens appeared to have similar efficacy profiles. These results, however, should be interpreted with caution because the network was dominated by indirect comparisons. Data from large RCTs that make direct comparisons between treatments are needed to detect the optimal induction regimen for elderly AML patients.

Selenium and glutathione peroxidase status in adult Egyptian patients with acute myeloid leukemia

This study was undertaken to evaluate selenium (Se) and glutathione peroxidase (GPX) status in patients with newly diagnosed acute myeloid leukemia (AML) before and after induction therapy. Twenty-five patients with newly diagnosed AML and 15 healthy age- and sex-matched control subjects were included in this study. Serum Se level by the graphite furnace atomic absorption spectrometric technique and GPX activity by an adaptation of Beutler method was performed for the patients before and after receiving the induction therapy. Serum Se level was significantly lower in patients with AML versus control subjects (63.1 ± 8.8 versus 77 ± 8.8 μg/L before therapy with a P value <0.01 and 69 ± 6.8 versus 77 ± 8.8 μg/L after therapy with a P value <0.01).GPX activity was significantly lower in patients with AML versus control subjects (1.6 ± 0.4 versus 3.4 ± 0.7 μ/g protein pretreatment with a P value <0.01 and 1.9 ± 0.6 versus 3.4 ± 0.7 μ/g protein post induction treatment with P value <0.01).Se level and GPX activity significantly increased in AML patients after treatment. Patients who accomplished complete remission after induction harbored significantly higher Se levels than resistant patients before and after treatment. There was no significant correlation between serum Se level and GPX activity. Decreased Se level and reduced GPX activity in AML patients support the association of carcinogenesis and subnormal Se states.

Maximum supportive care, standard conditioning and allogeneic stem cell transplantation for elderly patients with acute myelogenous leukemia

Dose-intense conditioning (DIC) (myeloablative) regimens for allogeneic stem cell transplantation (alloSCT) were previously avoided in patients with acute myelogenous leukemia aged more than 55 years because of the fear of excessive morbidity and mortality. The introduction of reduced-intensity conditioning (RIC) alloSCT led to their increasing use in these patients because of their reduced toxicity. Significant disadvantages remain, however, including the late establishment of a posttransplant graft-versus-leukemia effect and an overrepresentation of poor prognostic factors in elderly patients, resulting in the risk of early relapse/progression before the graft-versus-leukemia effect being disproportionally large. Preliminary results suggest that DIC with maximum prophylaxis and support is safe for elderly patients up to age 70 years. We hypothesize that DIC may be important for the early control of leukemia in elderly patients, and that prospective, randomized trials comparing DIC and RIC-based transplants should be carried out, with the expectation that early transplant-related mortality will be no different.

Erufosine, a novel alkylphosphocholine, in acute myeloid leukemia: single activity and combination with other antileukemic drugs

PURPOSE

Alkylphosphocholines represent a new class of cytostatic drugs with a novel mode of action. Erufosine (ErPC3), the first compound of this class that can be administered intravenously, has recently been shown to be active against human tumor and leukemic cell lines.

METHODS

In order to evaluate the antileukemic potential of ErPC3 in acute myeloid leukemia (AML) the lethal concentration 50% (LC 50) was determined using WST-1 assay. For analysis of cell death, staining for Annexin V and activated caspase 3 was performed. An interaction analysis was performed by calculation of combination index and construction of isobolograms.

RESULTS

The LC 50 was 7.4 microg/ml after 24 h and 3.2 microg/ml after 72 h in HL 60 cells and 30.1 and 8.6 microg/ml, respectively, in 19 fresh samples from patients with AML. ErPC3 was found to be cytotoxic in HL60 cells with distinct activation of caspase 3. ErPC3 was not cross-resistant with cytarabine, idarubicine and etoposide as shown by the linear relation of respective LC 50s. The latter agents, however, exerted an additive cytotoxicity in combination with ErPC3 as revealed by isobologram analysis and combination index, although results are uneven for idarubicine.

CONCLUSION

Based on these data ErPC3 appears as a novel antileukemic candidate drug, which needs to be explored further in the treatment of AML.

Cytotoxic activity of the third-generation bisphosphonate zoledronic acid in acute myeloid leukemia

The third-generation bisphosphonate zoledronic acid (ZOL) has recently been shown to be active against human tumour and leukemic cell lines. The purpose of this study was to evaluate the antileukemic potential of ZOL in acute myeloid leukemia (AML). We determined the lethal concentration 50% (LC 50) using the WST-1 assay of ZOL as being 287.9 microg/ml after 24 h and 108.3 microg/ml after 96 h in HL 60 cells and to be 382.4 and 43.2 microg/ml, respectively, in nine samples from patients with AML. The ZOL induced inhibition of proliferative activity of HL 60 cells could not be abrogated by the hematopetic growth factors G-CSF and GM-CSF. ZOL was found to by cytotoxic in HL 60 cells without activation of caspase 3. ZOL was not cross resistant with cytarabine as shown by the linear correlation of LC 50s. Both agents, however, exerted an additive cytotoxicity as revealed by isobologram-analysis and combination index. These data warrant further investigation of ZOL in the treatment of AML.

Chemotherapy Dosing Part I: Scientific Basis for Current Practice and Use of Body Surface Area

Cytotoxic chemotherapy is characterised by a low therapeutic index and significant variability in therapeutic and toxic effects. In an attempt to reduce this variability, most chemotherapy doses are individualised according to patient body surface area (BSA). This practice, which was introduced almost 50 years ago, clearly has practical and economic implications for the healthcare system. Furthermore, the clinical value of this approach has, in recent years, been questioned. Despite established practice, chemotherapy dose selection remains complicated, partly because treatment effects are difficult to measure, partly because drugs are used in combination with other treatment modalities, and also because the patient's condition may change with disease progression. Various patient-related factors can affect drug pharmacokinetics (PK) and pharmacodynamics (PD), for example organ function, expression and activity of metabolising enzymes, drug resistance, body size, gender, age, concomitant disease and co-administration of other drugs. These factors may be of clinical significance in chemotherapy dose determination and measures of PK, PD or both feature in attempts to devise more rigorous methods for chemotherapy dosing. Part I of this series of two reviews describes the history and clinical impact of BSA-based chemotherapy, and examines the scientific evidence to support BSA dosing. It evaluates the factors affecting PK and PD for specific drugs that could inform and refine dose determination.