Economic Evaluation of Elective Cesarean Section on Maternal Request Compared With Planned Vaginal Birth-Application to Swedish Setting Using National Registry Data.

OBJECTIVES: There is a lack of consensus around the definition of delivery by cesarean section (CS) on maternal request, and clinical practice varies across and within countries. Previous economic evaluations have focused on specific populations and selected complications. Our aim was to evaluate the cost-effectiveness of CS on maternal request compared with planned vaginal birth in a Swedish context, based on a systematic review of benefits and drawbacks and national registry data on costs. METHODS: We used the results from a systematic literature review of somatic risks for long- and short-term complications for mother and child, in which certainty was rated low, moderate, or high using the Grading of Recommendations Assessment, Development and Evaluation. Swedish national registry data were used for healthcare costs of delivery and complications. Utilities for long-term complications were based on a focused literature review. We constructed a decision tree and conducted separate analyses for primi- and multiparous women. Costs and effects were discounted by 3% and the time horizon was varied between 1 and 20 years. RESULTS: Planned vaginal birth leads to lower healthcare costs and somatic health gains compared with elective CS without medical indication over up to 20 years. Although there is uncertainty around, for example, quality-of-life effects, results remain stable across sensitivity analyses. CONCLUSIONS: CS on maternal request leads to increased hospitalization costs in a Swedish setting, taking into account short- and long-term consequences for both mother and child. Future research needs to study the psychological consequences related to different delivery methods, costs in outpatient care, and productivity losses.

Prevalence and initiation of statin therapy in the oldest old-a longitudinal population-based study.

PURPOSE: To investigate the prevalence and initiation of statins as well as treatment intensity in the oldest old, with younger olds as a reference. METHODS: A population-based cohort was used, including record-linked data from the Total Population Register, the Swedish Prescribed Drug Register, and the Swedish Patient Register. In each year over the study period (2009-2015), statin use was described in individuals 85 years or older and 65-84 years of age, and initiation rates were calculated among individuals with no statin treatment during a preceding 3-year period. RESULTS: A total of 1,764,836 individuals ≥ 65 years in 2009, increasing to 2,022,764 in 2015, were included in the analyses. In individuals 85 years or older, the prevalence of statin therapy increased from 11% in 2009 to 16% in 2015, the corresponding initiation rates being 1.3% and 1.7%, respectively. Corresponding prevalence and incidence figures in 65-84-year-olds were 23 to 25% and 3.0 to 3.3%, respectively. Overall, the proportion of individuals initiating statin with high-intensity treatment (atorvastatin ≥ 40 mg or rosuvastatin ≥ 20 mg) in the oldest old increased from 1 to 36% during the study period, and a similar increase was seen in the younger age group. Over the study years, the presence of an established indication for statin treatment varied between 70 and 76% in the oldest old and between 30 and 39% in the younger olds. CONCLUSION: Prevalence and initiation of statin therapy are increasing among the oldest old, despite the fact that randomized controlled trials focusing on this age group are lacking and safety signals are difficult to detect.

Use of statins in the elderly according to age and indication-a cross-sectional population-based register study.

PURPOSE: To investigate statin use in the elderly by age (≥ 80 vs. 65-79 years) in relation to established indications. METHODS: A population-based cohort, including data from four registers, encompassing inhabitants in Region Västra Götaland, Sweden, was used. Statin users were defined as those filling statin prescriptions ≥ 75% of the year 2010. Primary care and hospital diagnoses in 2005-2010 regarding ischemic heart disease, stroke, transient ischemic attacks, and diabetes were considered established indications. RESULTS: A total of 278,205 individuals were analyzed. In individuals aged ≥ 80 and 65-79 years (n = 81,885 and n = 196,320, respectively), 17% (95% confidence interval 17%; 18%) and 23% (23%; 23%) respectively, were statin users. Among the statin users, 74% (73%; 74%) of those aged ≥ 80 and 60% (59%; 60%) of those aged 65-79 years had ≥ 1 established indication. Conversely, of those with ≥ 1 established indication, 30% (30%; 31%) and 53% (52%; 53%) were on statins in the respective age groups. Logistic regression revealed that age, nursing home residence, and multi-dose drug dispensing were the most prominent negative predictors for statin use; adjusted odds ratios (95% confidence interval): 0.45 (0.44; 0.46), 0.39 (0.36; 0.42), and 0.47 (0.44; 0.49), respectively. CONCLUSIONS: In the oldest old (≥ 80 years), statin users were fewer and had more often an established indication, suggesting that physicians extrapolate scientific evidence for beneficial effects in younger age groups to the oldest, but require a more solid ground for treatment. As the oldest old, nursing home residents, and those with multi-dose drug-dispensing were statin users to a lesser extent, physicians may often refrain from treatment in those with lower life expectancy, either due to age or to severely reduced health status. In both age groups, our results however also indicate some over- as well as undertreatment.

Long-term use of proton pump inhibitors and prevalence of disease- and drug-related reasons for gastroprotection-a cross-sectional population-based study.

PURPOSE: To analyse the prevalence of long-term use of proton pump inhibitors (PPI) with respect to underlying diseases and drugs, and to find predictors for such treatment when an evident rationale for the PPI treatment is lacking. METHODS: The study cohort consisted of individuals, ≥65 years in 2010, residing in the Region Västra Götaland during 2005-2010. For individuals with and without long-term use of PPI in 2010, we investigated the prevalence of an underlying diagnosis, that is, an acid-related disease during the five preceding years, as well as concomitant long-term use of antiplatelet agents or cyclooxygenase inhibitors. RESULTS: In all, 278 205 individuals (median age: 74 years; 55% female; median 3 drugs per person; 5% nursing home residents, 11% with multi-dose drug dispensing) were included in the analyses, 32 421 (12%) of whom were on long-term treatment with PPI in 2010. For 12 253 individuals (38%) with such treatment, no underlying rationale was found. In individuals without a disease- or a drug-related reason for PPI use, nursing home residence, number of drugs, female sex, but not multi-dose drug dispensing, were associated with long-term use of PPI; adjusted odds ratios (95% confidence interval): 1.63 (1.49; 1.78), 1.27 (1.26; 1.28), 1.24 (1.19; 1.29), and 0.94 (0.88; 1.01), respectively. CONCLUSIONS: Long-term use of PPI occurs in one out of nine individuals in the older population. For four out of ten of these, no reason for PPI use can be identified. Nursing home residence, female sex, and greater number of drugs predict non-rational long-term use of PPI. © 2016 The Authors. Pharmacoepidemiology and Drug Safety published by John Wiley & Sons Ltd.

Pronounced Interindividual But Not Intraindividual Variation in Tamoxifen and Metabolite Levels in Plasma During Adjuvant Treatment of Women With Early Breast Cancer.

BACKGROUND: Tamoxifen is still an important antihormonal treatment option for patients with breast cancer and estrogen receptor-positive tumors. More than 20% of patients relapse despite treatment. The drug is usually dosed 20 mg/d irrespective of interindividual variation in drug clearance. To study interindividual and intraindividual variation in plasma levels we measured tamoxifen and metabolite levels in plasma on 2 occasions, with at least 4 weeks in between, of 39 women (19 premenopausal and 20 postmenopausal women) on adjuvant treatment (20 mg/d) of early breast cancer. METHODS: We used an ultra-performance liquid chromatography with a mass spectrometry detection method for identification and quantification of tamoxifen, N-desmethyltamoxifen, 4-OH-tamoxifen, and endoxifen. Follicle-stimulating hormone, luteinizing hormone, and estradiol levels were also measured. RESULTS: The plasma concentrations of tamoxifen and its metabolites showed a pronounced interindividual variation, whereas intraindividual concentrations were rather stable. Despite the same dosage, interindividual tamoxifen concentrations varied from 51 to 307 ng/mL (124 ± 57, mean ± SD) and endoxifen values showed a range from 3.2 to 19 ng/mL (10.4 ± 5.2, mean ± SD), that is, 6-fold variation for both. CONCLUSIONS: Large interindividual variation of tamoxifen and endoxifen with stable intraindividual levels, and too low levels of endoxifen in a considerable proportion of patients strongly support that therapeutic drug monitoring and individualized dosing could lead to optimal exposure and hopefully better outcome. A randomized outcome study between conventional dosing and therapeutic drug monitoring-guided dosing is needed to show whether this approach works.

Biosimilar erythropoiesis-stimulating agents and the risk of developing anti-drug antibodies-a systematic review.

PURPOSE: We systematically reviewed published observational studies and randomized controlled trials (RCT) reports of clinical trials on erythropoiesis-stimulating agents (ESA's). Only studies evaluating the risk of developing anti-drug antibodies (ADA) of both original and biosimilar drugs were chosen. METHODS: Databases including PubMed, EMBASE and Cochrane Library were searched up to 17 March 2015. Two reviewers independently assessed the relevant studies for risk of bias. RESULTS: Twenty-one publications were included. The overall prevalence of ADA in the studies was about 0.2 to 0.5 %. Most studies were not designed to monitor the development of ADA and often the study duration was too short (less than 6 months) and the patient population too small. Moreover, in many studies, the assays used only determined the presence of ADA and did not measure therapy failure due to ADA. In one RCT, as many as 13 cases (4 %) of ADA were identified. CONCLUSION: ADA development seems to be low in short-term studies with ESA. None of the efficacy and safety issues for ESA biosimilars were judged to be adequately addressed in the evaluated literature, with respect to ADA formation, due to the study design and the assay method used.

Differential role of thiopurine methyltransferase in the cytotoxic effects of 6-mercaptopurine and 6-thioguanine on human leukemia cells.

The thiopurine antimetabolites, 6-mercaptopurine (6-MP) and 6-thioguanine (6-TG) are inactive pro-drugs that require intracellular metabolism for activation to cytotoxic metabolites. Thiopurine methyltransferase (TPMT) is one of the most important enzymes in this process metabolizing both 6-MP and 6-TG to different methylated metabolites including methylthioinosine monophosphate (meTIMP) and methylthioguanosine monophosphate (meTGMP), respectively, with different suggested pharmacological and cytotoxic properties. While meTIMP is a potent inhibitor of de novo purine synthesis (DNPS) and significantly contributes to the cytotoxic effects of 6-MP, meTGMP, does not add much to the effects of 6-TG, and the cytotoxicity of 6-TG seems to be more dependent on incorporation of thioguanine nucleotides (TGNs) into DNA rather than inhibition of DNPS. In order to investigate the role of TPMT in metabolism and thus, cytotoxic effects of 6-MP and 6-TG, we knocked down the expression of the gene encoding the TPMT enzyme using specifically designed small interference RNA (siRNA) in human MOLT4 leukemia cells. The knock-down was confirmed at RNA, protein, and enzyme function levels. Apoptosis was determined using annexin V and propidium iodide staining and FACS analysis. The results showed a 34% increase in sensitivity of MOLT4 cells to 1µM 6-TG after treatment with TPMT-targeting siRNA, as compared to cells transfected with non-targeting siRNA, while the sensitivity of the cells toward 6-MP was not affected significantly by down-regulation of the TPMT gene. This differential contribution of the enzyme TPMT to the cytotoxicity of the two thiopurines is probably due to its role in formation of the meTIMP, the cytotoxic methylated metabolite of 6-MP, while in case of 6-TG methylation by TPMT substantially deactivates the drug.

Inverse relationship between leukaemic cell burden and plasma concentrations of daunorubicin in patients with acute myeloid leukaemia.

AIMS: It has been shown that the cellular uptake and cytotoxicity of anthracyclines decrease with increasing cell density in vitro, an event termed 'the inocculum effect'. It is not known whether such an effect occurs in vivo. In this study the relationships between white blood cell (WBC) count, plasma and cellular concentrations of daunorubicin (DNR) in patients with acute myeloid leukaemia were investigated. METHODS: Plasma and mononuclear blood cells were isolated from peripheral blood from 40 patients with acute myeloid leukaemia at end of infusion (time 1 h), 5 and 24 h following the first DNR infusion. DNR concentrations were determined by high-pressure liquid chromatography and related to the WBC count at diagnosis. A population pharmacokinetic model was used to estimate the correlations between baseline WBC count, volume of distribution and clearance of DNR. RESULTS: A clear but weak inverse relationship between the baseline WBC count and plasma concentrations of DNR (r(2)=0.11, P<0.05) at time 1 was found. Furthermore, a clear relationship between baseline WBC count and DNR central volume of distribution using population pharmacokinetic modelling (dOFV 4.77, P<0.05) was also noted. Analysis of plasma DNR and the metabolite daunorubicinol (DOL) concentrations in patients with a high WBC count support that the low DNR/DOL concentrations are due a distribution effect. CONCLUSION: This study shows that the leukaemic cell burden influences the plasma concentrations of anthracyclines. Further studies are needed to explore if patients with high a WBC count may require higher doses of anthracyclines.

Uptake of anthracyclines in vitro and in vivo in acute myeloid leukemia cells in relation to apoptosis and clinical response.

AIMS: To study anthracycline-induced apoptosis in leukemic cells isolated from patients with acute myelogenous leukemia (AML) in vitro and to compare intracellular anthracycline concentrations causing apoptosis in vitro with those obtained in vivo during anthracycline treatment. METHODS: Mononuclear blood cells from AML patients were isolated before (n = 20) and after anthracycline infusion (n = 24). The pre-treated cells were incubated in vitro with daunorubicin (DNR) and/or idarubicin (IDA). Anthracycline concentrations were determined by high-performance liquid chromatography, and apoptosis was detected by propidium iodine staining using a flow cytometer. RESULTS: There was a clear concentration-response relationship between intracellular anthracycline levels and apoptosis albeit with a large interindividual variation. Intracellular levels >1200 muM always led to high apoptosis development (>60%) in vitro. The intracellular concentrations of DNR in vivo (n = 24) were more than tenfold lower than the concentrations needed to induce effective apoptosis in vitro, although a significant relation between in vivo concentrations and clinical remission was found. We also found a significant relation between apoptosis induction in leukemic cells by IDA in vitro and clinical remission. CONCLUSIONS: Our results indicate that intracellular anthracycline levels in vivo are suboptimal and that protocols should be used that increase intracellular anthracycline levels.

Plasma concentrations of lamotrigine and its 2-N-glucuronide metabolite during pregnancy in women with epilepsy.

OBJECTIVE: To further characterize pregnancy-induced alterations in the pharmacokinetics of lamotrigine (LTG). METHODS: Fifteen women treated with LTG were studied during 17 pregnancies. Complete trough blood samples from all trimesters and baseline > 1 month after delivery were available for 12 pregnancies (Group A), whereas, five contributed with samples only from the third trimester and baseline (Group B). High-performance liquid chromatography (HPLC) was used to determine LTG plasma concentrations, and liquid chromatography-mass spectrometry to assay the main metabolite 2-N-lamotrigine glucuronide (2-N-GLUC) in plasma. RESULTS: In group A, the mean dose/plasma concentration ratio (D/C) of LTG at baseline after pregnancy was 66.5 +/- 17.9 (+/- SD) L/day and approximately 250% higher in late pregnancy. The mean lamotrigine-2-N-glucuronide/lamotrigine plasma concentration ratio (2-N-GLUC/LTG) was 0.349 +/- 0.141 (+/- SD) at baseline and 147% higher in late pregnancy. Taking group A and B together, the 2-N-GLUC/LTG ratio was 175% higher in the third trimester compared to baseline. CONCLUSION: Our study confirms a significant decline in LTG plasma levels during pregnancy in women on monotherapy with LTG. An increased 2-N-GLUC/LTG ratio suggests that this decline may be related to an increased metabolism of LTG by glucuronidation.

Acute Myelogenous Leukemia Cells Secrete Factors that Stimulate Cellular LDL Uptake via Autocrine and Paracrine Mechanisms.

Leukemic cells isolated from most patients with acute myelogenous leukemia (AML) have higher low density lipoprotein (LDL) uptake than normal mononuclear blood cells. Little is known, however, about the mechanism behind the elevated LDL uptake. We investigated if AML cells secrete factors that stimulate cellular LDL uptake. Mononuclear blood cells were isolated from peripheral blood from 42 patients with AML at diagnosis. Cellular LDL uptake was determined from the degradation rate of 125I-labelled LDL. Conditioned media from AML cells stimulated the LDL degradation in the leukemic cell lines KG1 and HL60, and in isolated AML cells. The stimulatory effect correlated with the LDL degradation in the AML cells directly after isolation from blood. Conditioned media also autostimulated LDL degradation in the AML cells themselves. Concentrations of IL-6 and IL-8 in AML cell conditioned media correlated with the LDL degradation in AML cells directly after isolation from blood. Addition of R-TNF-α, but not IL-6 or IL-8, stimulated LDL degradation in HL60, KG1, and AML cells. The LDL degradation in AML cells could be inhibited by a LDL receptor blocking antibody. AML cells secrete factors that stimulate LDL uptake in a paracrine and autocrine pattern which open up therapeutic possibilities to inhibit the uptake of LDL by administration of antibodies to these factors.

GRADE equity guidelines 1: considering health equity in GRADE guideline development: introduction and rationale.

OBJECTIVES: This article introduces the rationale and methods for explicitly considering health equity in the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology for development of clinical, public health, and health system guidelines. STUDY DESIGN AND SETTING: We searched for guideline methodology articles, conceptual articles about health equity, and examples of guidelines that considered health equity explicitly. We held three meetings with GRADE Working Group members and invited comments from the GRADE Working Group listserve. RESULTS: We developed three articles on incorporating equity considerations into the overall approach to guideline development, rating certainty, and assembling the evidence base and evidence to decision and/or recommendation. CONCLUSION: Clinical and public health guidelines have a role to play in promoting health equity by explicitly considering equity in the process of guideline development.

GRADE equity guidelines 3: considering health equity in GRADE guideline development: rating the certainty of synthesized evidence.

OBJECTIVES: The aim of this paper is to describe a conceptual framework for how to consider health equity in the Grading Recommendations Assessment and Development Evidence (GRADE) guideline development process. STUDY DESIGN AND SETTING: Consensus-based guidance developed by the GRADE working group members and other methodologists. RESULTS: We developed consensus-based guidance to help address health equity when rating the certainty of synthesized evidence (i.e., quality of evidence). When health inequity is determined to be a concern by stakeholders, we propose five methods for explicitly assessing health equity: (1) include health equity as an outcome; (2) consider patient-important outcomes relevant to health equity; (3) assess differences in the relative effect size of the treatment; (4) assess differences in baseline risk and the differing impacts on absolute effects; and (5) assess indirectness of evidence to disadvantaged populations and/or settings. CONCLUSION: The most important priority for research on health inequity and guidelines is to identify and document examples where health equity has been considered explicitly in guidelines. Although there is a weak scientific evidence base for assessing health equity, this should not discourage the explicit consideration of how guidelines and recommendations affect the most vulnerable members of society.

Cytotoxic effect of a lipophilic alkylating agent after incorporation into low density lipoprotein or emulsions: studies in human leukemic cells.

The use of low density lipoprotein (LDL) as drug carrier in acute myeloblastic leukemia chemotherapy is attractive due to high LDL uptake by leukemic cells. Lipid-based formulations, such as liposomes or microemulsions are promising alternatives. In the current study, we incorporated N-trifluoroacetyl-adriamycin-14-valerate (AD32), a lipophilic derivative of daunorubicin (DNR), and WB4291, a lipophilic alkylating agent, into LDL or lipid microemulsions and evaluated their cytotoxic activities towards leukemic cell lines using as references DNR and melphalan. The incorporation of AD32 into LDL or emulsion resulted in complexes with poor cytotoxicity. WB4291-LDL and WB4291-emulsion exerted, on the other hand, promising cytotoxic effects towards parental and resistant K562 and HL60 cell lines.

Aromatase inhibitors alone or sequentially combined with tamoxifen in postmenopausal early breast cancer compared with tamoxifen or placebo - Meta-analyses on efficacy and adverse events based on randomized clinical trials.

Tamoxifen (TAM) and aromatase inhibitors (AI) are adjuvant therapy options for postmenopausal women with estrogen receptor positive (ER+) breast cancer. This systematic review of seven randomized controlled studies comparing TAM and AI, and one study comparing extended therapy with an AI with placebo after about 5 years of tamoxifen, aims to assess long-term clinical efficacy and adverse events. The literature review was performed according to the principles of the Cochrane Collaboration. The search included common databases up to 2013-01-14. Studies of high or moderate quality were used for grading of evidence. Revman™ software was utilized for meta-analyses of published data. Disease free survival (DFS) and overall survival (OS) were improved with AI monotherapy compared to TAM with high and moderate quality of evidence respectively. Sequenced therapy with AI → TAM (or vice versa) improved DFS compared with TAM with moderate quality of evidence, but did not improve OS (low quality of evidence). However, if only studies on sequenced AI therapy with randomization before endocrine therapy were considered, no improvement of DFS could be found. Fractures are more frequently associated with AI whereas the risk of endometrial cancer and venous thromboembolism are higher with TAM. For cardiovascular events no difference was found between AI (mono- or sequenced therapy) and TAM, whereas sequenced therapy compared with AI had lower risk of cardiovascular events (moderate level of evidence). AIs are superior to TAM as adjuvant hormonal therapy for postmenopausal ER-positive breast cancer. TAM can be considered for individual patients due to the different toxicity profile compared with AI. Cardiovascular events related to AI treatment deserve further attention.

Drastic effect of cell density on the cytotoxicity of daunorubicin and cytosine arabinoside.

White blood cell count (WBC) is generally accepted as a prognostic risk factor in acute myeloid leukemia (AML) outcome and displays a marked interindividual variation. The dose regimen currently used ignores the size of the tumor burden and the standardization of the dose is generally based on body surface area. In this study we have investigated the effect of cell density on the cytotoxic activity of daunorubicin (DNR) and cytosine arabinoside (AraC) towards HL60 cells and leukemic cells isolated from patients with AML. We demonstrate that drug cytotoxicity decreased with cell density and that apoptosis induction by DNR in isolated leukemic cells was greatly reduced at higher cell density. A marked reduction of the uptake of DNR and AraC in HL60 parental and mitoxantrone resistant cells was observed with increasing cell density. Such a drug depleting effect by cells at high density has been previously described for vincristine, doxorubicin and paclitaxel. By extrapolating the in vitro results to the in vivo situation, one could hypothesize that a high WBC can lower the plasma concentration through high uptake in the tumor burden, leading to a shortage of drug in leukemic blasts. Patients with high WBC might therefore benefit from a dose increase of DNR and/or AraC.

Elevated uptake of low density lipoprotein by drug resistant human leukemic cell lines.

Overexpression of a 170kD membrane glycoprotein, P-glycoprotein (Pgp), which acts as an energy dependent efflux pump for cytotoxic drugs is believed to be one of the factors that is responsible for clinical drug resistance. Recent studies suggest that Pgp is also responsible for the intracellular transport of cholesterol from the plasma membrane to the endoplasmic reticulum. Leukemic cells from patients with acute myelogenous leukemia have an elevated uptake of low density lipoprotein (LDL) when compared with white blood cells from healthy individuals. Since elevated LDL receptor expression and multidrug resistance are both common events in leukemic cells, we investigated LDL receptor expression in sensitive and drug resistant human leukemic cell lines. We found a 2- to 10-fold higher uptake of LDL in five out of five drug resistant K562 cell lines. All three drug resistant HL60 cell lines studied also had higher uptake than the parental cells. The LDL receptor expression in vincristine resistant Pgp positive K562 cells was less sensitive to downregulation by sterols than in parental cells. There was no selective effect of the Pgp inhibitor PSC-833 or other Pgp modulators on LDL receptor activity in Pgp positive cells. Since also resistant Pgp, multidrug resistance protein 1, and breast cancer resistance protein negative cells exhibited an elevated LDL receptor activity, we conclude that overexpression of these proteins is not the mechanism behind the elevated LDL uptake in the drug resistant leukemic cell lines. The findings are of interest for the concept of using lipoproteins as carriers of cytotoxic drugs in cancer treatment.

Relationship between daunorubicin concentration and apoptosis induction in leukemic cells.

Aiming to determine if a concentration window exists in which apoptosis induction by daunorubicin (DNR) is optimal, we studied the relationship between DNR concentration and apoptosis induction in HL60 and K562 cells and in peripheral leukemic cells isolated from three patients with acute myelogenous leukemia (AML). Cells were incubated for 2hr with increasing DNR concentrations and thereafter for 22hr in drug-free medium. Apoptosis was measured by detection of caspase-3-like activity and DNA fragmentation assayed by propidium iodide and flow cytometry. High DNR concentrations initiated faster apoptosis in HL60 cells and in AML cells, as shown by caspase-3 and DNA fragmentation data. DNA fragmentation into small fragments was preceded by the formation of a narrow peak on the left side of the G1 peak, most likely large DNA fragments, but further studies are required for unequivocal confirmation. This peak could easily be misinterpreted as a G1 peak without careful time monitoring. In K562 cells, no left peak was detected, apoptosis was slow and not related to concentration. In AML cells, large interindividual variations were observed in the time course of DNA fragmentation at 0.25microg DNR/mL. In conclusion, our findings support the concept of dose intensification for optimal apoptosis induction as higher doses correlate with earlier and more rapid caspase-3 induction and DNA fragmentation in leukemic cells. The DNA fragmentation assay may be a valuable tool to determine leukemic cells' chemosensitivity to apoptosis.