Gene expression profiling for the diagnosis of acute leukaemia

An optimised diagnostic setting in acute leukaemias combines cytomorphology and cytochemistry, multiparameter immunophenotyping, cytogenetics, fluorescence in situ hybridisation, and polymerase chain reaction (PCR)-based assays. This allows classification and definition of biologically defined and prognostically relevant subtypes, and allows directed treatment in some sub-entities. Over the last years the microarray technology has helped to quantify simultaneously the expression status of ten thousands of genes in single experiments. This novel approach will hopefully become an essential tool for the molecular classification of acute leukaemias in the near future. It can be anticipated that new biologically defined and clinically relevant subtypes of leukaemia will be identified based on their unique gene expression profiles. This method may therefore guide therapeutic decisions and should be investigated in a diagnostic setting in parallel to established standard methods.

Is the frequency of self-monitoring of blood glucose related to long-term metabolic control? Multicenter analysis including 24,500 patients from 191 centers in Germany and Austria

Blood glucose measurements are generally accepted components of a modern diabetes self-management. The value of self-monitoring of blood glucose (SMBG) is, however, discussed controversially and only a few studies addressed the efficacy of SMBG under real-life conditions so far. In order to investigate whether the frequency of SMBG is related to long-term metabolic control, data from the DPV-Wiss-database, a standardized,prospective, computer-based documentation of diabetes care and outcome, were analyzed for patients with type 1(n = 19,491) and type 2 (n = 5,009) diabetes from 191 centers in Germany and Austria. Local HbA1c reference ranges were mathematically adjusted to the DCCT reference. For each patient, data from the most recent year of diabetes care were used. On average,patients with type 1 diabetes performed 4.4 blood glucose measurements/day. Corrected for age, gender, diabetes duration,on intensified (>or=4 daily injections or CSII) therapy (HbA1c reduction of 0.32% for one additional SMBG/day) compared to patients on conventional (1-3 daily injections) therapy(HbA1c-reduction of 0.16% for one additional SMBG/day). In 2,021 patients with insulin-treated type 2 diabetes (2.7 measurements/day), more frequent SMBG was associated with better metabolic control (HbA1c-reduction of 0.16% for one additionalSMBG/day, p < 0.0001), while in 2,988 patients on OAD or diet alone (2.0 measurements/day), more frequent blood glucose measurements were associated with higher HbA1c-levels(HbA1c-increase of 0.14% for one additional SMBG/day,p < 0.0001). These data indicate that more frequent SMBG are associated with better metabolic control in both, patients with type 1 and insulin-treated type 2 diabetes. Since no benefit ofSMBG on metabolic control was found in patients with type 2 diabetes on OAD or diet alone, SMBG should primarily be recommended for those patients with suboptimal metabolic control whereas the benefit of SHBG in non-insulin-treated patients with adequate HbA1c-levels remains uncertain.insulin therapy and center difference, the SMBG frequency was associated with better metabolic control (HbA1c-reduction of0.26% for one additional SMBG/day, p < 0.0001). HbA1c-reduction with higher frequency of SMBG was more pronounced in patients Blood glucose measurements are generally accepted components of a modern diabetes self-management. The value of self-monitoring of blood glucose (SMBG) is, however, discussed controversially and only a few studies addressed the efficacy of SMBG under real-life conditions so far. In order to investigate whether the frequency of SMBG is related to long-term metabolic control, data from the DPV-Wiss-database, a standardized,prospective, computer-based documentation of diabetes care and outcome, were analyzed for patients with type 1(n = 19,491) and type 2 (n = 5,009) diabetes from 191 centers in Germany and Austria. Local HbA1c reference ranges were mathematically adjusted to the DCCT reference. For each patient, data from the most recent year of diabetes care were used. On average,patients with type 1 diabetes performed 4.4 blood glucose measurements/day. Corrected for age, gender, diabetes duration,insulin therapy and center difference, the SMBG frequency wasassociated with better metabolic control (HbA1c-reduction of 0.26% for one additional SMBG/day, p < 0.0001). HbA1c-reduction with higher frequency of SMBG was more pronounced in patients on intensified (>or= 4 daily injections or CSII) therapy (HbA1c reduction of 0.32% for one additional SMBG/day) compared to patients on conventional (1-3 daily injections) therapy(HbA1c-reduction of 0.16% for one additional SMBG/day). In 2,021 patients with insulin-treated type 2 diabetes (2.7 measurements/day), more frequent SMBG was associated with better metabolic control (HbA1c-reduction of 0.16% for one additionalSMBG/day, p < 0.0001), while in 2,988 patients on OAD or diet alone (2.0 measurements/day), more frequent blood glucose measurements were associated with higher HbA1c-levels(HbA1c-increase of 0.14% for one additional SMBG/day, p < 0.0001). These data indicate that more frequent SMBG are associated with better metabolic control in both, patients with type 1 and insulin-treated type 2 diabetes. Since no benefit of SMBG on metabolic control was found in patients with type 2 diabetes on OAD or diet alone, SMBG should primarily be recommended for those patients with suboptimal metabolic control whereas the benefit of SHBG in non-insulin-treated patients with adequate HbA1c-levels remains uncertain.

Antiviral prophylaxis in patients with haematological malignancies and solid tumours: Guidelines of the Infectious Diseases Working Party (AGIHO) of the German Society for Hematology and Oncology (DGHO)

Morbidity and mortality in patients with malignancies are increased by viral infections. These mostly are reactivations of asymptomatic latent infections. They primarily concern clinical entities associated with the reactivation of herpes viruses, such as varicella zoster virus (VZV) and cytomegalovirus (CMV). Respiratory tract infections caused by influenza, parainfluenza or respiratory syncytial virus (RSV) are less common. Since reactivation of latent infections has major clinical impact, antiviral prophylaxis is an attractive approach for patients expecting immunosuppression. The main risk factor for clinically relevant reactivation is profound disruption of cellular immune response. Duration and severity of chemotherapy induced neutropenia are of lesser importance. The risk of viral complications rises significantly in the presence of sustained suppression of T-cell function, e.g. in recipients of allogeneic stem cell transplants or of alemtuzumab (Campath-1H) antibody therapy. The objective of this guideline is to review the basis of prophylactic strategies and to provide recommendations for clinicians treating patients with haematological malignancies and solid tumors.

An international multi-center study to assess the clinical accuracy of the molecular subclassification of leukemia by gene expression profiling

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Background: Microarray analysis can identify differentially expressed genes of pediatric and adult leukemias. Recently, the MILE (Microarray Innovations in Leukemia) study has started in 11 centers (European Leukemia Network: 7, USA: 3, Singapore: 1). MILE compares the accuracy of gene expression profiles of 16 acute and chronic leukemia subclasses, MDS, and non-leukemia as control group to routine diagnostic workup. Methods: In a pre-phase each center was trained on the identical microarray protocol (HG-U133 Plus 2.0 microarrays). 2 cell lines (MCF-7, HEPG2) and cell lysates of three leukemia patients (AML t(8;21), CML, CLL) were tested. After proficiency testing, centers started to analyze 2000 leukemia samples. Results: The pre-phase demonstrated a very high intra- and inter-laboratory comparability among centers. Using principal component analysis each sample type was clustered with no observable sub-grouping of the different centers. Replicates of leukemia samples demonstrated squared correlation coefficients between 0.930–0.997 for CML, 0.936–0.998 for CLL, and 0.940–0.999 for AML t(8;21).Here we present classification results of the first series of 607 pts. that were included prospectively in a training data set (total n=1,049) to form linear classifiers for all 153 class pairs. The average cross-validation accuracy is 89.4%. In first independent cohort (HG-U133 Plus 2.0, n=105) 89.5% classification accuracy were achieved. In a second independent cohort (n=1,094), analyzed previously in two centers on HG-U133A/B microarrays, 83.5% classification accuracy were achieved. In detail, 136 out of 139 (97.8%) chronic leukemia samples (CML or CLL) were classified fully in agreement with standard diagnostic procedures. For acute leukemia subtypes 767 out of 904 (84.8%) were classified correctly. Interestingly, an AML-like signature can be found in MDS samples with IPSS >1.5. Conclusions: This international multi-center study demonstrates a very high inter- and intralaboratory reproducibility of microarray analyses. Data will be used to design a new custom format microarray dedicated to further develop the application of gene expression profiling for diagnosis and subclassification of leukemia.

No significant financial relationships to disclose.

The selfish brain: competition for energy resources

Although the brain constitutes only 2% of the body mass, its metabolism accounts for 50% of total body glucose utilization. This delicate situation is aggravated by the fact that the brain depends on glucose as energy substrate. Thus, the contour of a major problem becomes evident: how can the brain maintain constant fluxes of large amounts of glucose to itself in the presence of powerful competitors as fat and muscle tissue. Activity of cortical neurons generates an "energy on demand" signal which eventually mediates the uptake of glucose from brain capillaries. Because energy stores in the circulation (equivalent to ca. 5 g glucose) are also limited, a second signal is required termed "energy on request"; this signal is responsible for the activation of allocation processes. The term "allocation" refers to the activation of the "behavior control column" by an input from the hippocampus-amygdala system. As far as eating behavior is concerned the behavior control column consists of the ventral medial hypothalamus (VMH) and periventricular nucleus (PVN). The PVN represents the central nucleus of the brain's stress systems, the hypothalamus-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS). Activation of the sympatico-adrenal system inhibits glucose uptake by peripheral tissues by inhibiting insulin release and inducing insulin resistance and increases hepatic glucose production. With an inadequate "energy on request" signal neuroglucopenia would be the consequence. A decrease in brain glucose can activate glucose-sensitive neurons in the lateral hypothalamus (LH) with the release of orexigenic peptides which stimulate food intake. If the energy supply of the brain depends on activation of the LH rather than on increased allocation to the brain, an increase in body weight is evitable. An increase in fat mass will generate feedback signals as leptin and insulin, which activate the arcuate nucleus. Activation of arcuate nucleus in turn will stimulate the activity of the PVN in a way similar to the activation by the hippocampus-amydala system. The activity of PVN is influenced by the hippocampal outflow which in turn is the consequence of a balance of low-affinity and high-affinity glucocorticoid receptors. This set-point can permanently be displaced by extreme stress situations, by starvation, exercise, hormones, drugs or by endocrine-disrupting chemicals. Disorders in the "energy on request" process will influence the allocation of energy and in so doing alter the body mass of the organism. In this "selfish brain theory" the neocortex and the limbic system play a central role in the pathogenesis of diseases, such as anorexia nervosa, obesity and diabetes mellitus type II. From these considerations it appears that the primary disturbance in obesity is a displacement of the hippocampal set-point of the system. The resulting permanent activation of the feedback system must result in a likewise permanent activation of the sympatico-adrenal system, which induces insulin resistance, hypertension and the other components of the metabolic syndrome. Available therapies for treatment of the metabolic syndrome (blockade of alpha- and beta-adrenergic receptors, insulin and insulin secretagogues) interfere with mechanisms, which must be considered compensatory. This explains why these therapies are disappointing in the long run. New therapeutic strategies based on the "selfish brain theory" will be discussed.

Towards a pathogenesis-oriented therapy of acute myeloid leukemia

Genetic and molecular techniques have provided increasing insights into the biology of acute myeloid leukemia (AML). These investigations showed that AML is not a homogeneous disease but a heterogeneous group of biologically different subentities. These subentities are currently primarily defined by cytogenetics by which three main subgroups can be discriminated: AML with balanced translocations, AML with unbalanced aberrations and AML without cytogenetically detectable aberrations. Within the latter group molecular alterations are identified in more than half of cases such as NPM mutations, FLT3 mutations, MLL duplications and mutations of CEBP-alpha. The clinical meaning of these findings is illustrated by substantial differences in response to therapy and long-term outcome. As demonstrated by the recent multicenter trial of the German AML Cooperative Group (AMLCG) and other studies intensification of induction therapy may improve the results in distinct subtypes but fails to do so in others. Therefore, new strategies need to be explored which incorporate the knowledge about the biology of AML to develop biology adapted treatment strategies. This process has just begun and is predominantly determined by the availability of new agents and their evaluation in clinical phase I and II studies. A variety of targets are currently explored and some trials have yielded promising results already. The step towards a biology adapted treatment of AML is long and requires the combined efforts of researchers, clinicians and the pharmaceutical industry. The first steps towards this goal have been taken and give rise to the hope for more effective and more specific therapies of AML.

Serum adiponectin concentrations during a 72-hour fast in over- and normal-weight humans

OBJECTIVE

Adiponectin is currently considered an important link between obesity and insulin resistance, since circulating levels of this insulin sensitizing hormone have consistently been found to be reduced in obese subjects. However, until now it is not known how the secretion of adiponectin is regulated in response to acute metabolic changes. Here, we assessed the influence of complete fasting for 72 h on serum adiponectin levels.

DESIGN

Between group comparison of repeated measurements.

SUBJECTS

In total, 18 normal-weight (mean+/-s.e.m. BMI: 22.2+/-0.4 kg/m(2); age: 39.2+/-4.4 y) and nine over-weight (BMI: 33.2+/-1.8 kg/m(2); age: 36.9+/-4.5 y) subjects.

MEASUREMENTS

Serum adiponectin levels were measured every 4 h during a 72-h fasting period. Additionally, concentrations of plasma glucose and serum insulin and leptin were assessed at the beginning and in the end of the fasting experiment. Insulin resistance was estimated using the homeostasis model assessment (HOMA).

RESULTS

While concentrations of glucose, insulin, and leptin decreased across the fasting period by 31.0, 33.1 and 60.0%, respectively (all P<0.005), adiponectin levels remained unchanged (P=0.817). Overall, over-weight subjects exhibited slightly lower adiponectin levels than normal-weight subjects (P=0.092), but there was no difference in the time course of adiponectin levels during fasting between these two groups (P=0.970). Although, averaged adiponectin levels before and after fasting did not systematically differ, individual changes in adiponectin levels across fasting displayed a slight but significant inverse correlation with changes in plasma glucose concentration (r=-0.42, P=0.03).

DISCUSSION

The data show that serum adiponectin concentrations remain remarkably stable during 72 h of fasting in normal- and over-weight subjects. Thus, adiponectin appears to reflect primarily long-term changes in body weight with little evidence for a dependence on short-term regulatory influences.

Antecedent hypoglycaemia attenuates vascular endothelial growth factor response to subsequent hypoglycaemia in healthy men

AIM

The plasma concentration of vascular endothelial growth factor (VEGF) has recently been shown to increase sharply in response to hypoglycaemia and, thus, has been proposed as having a role in hypoglycaemia counter-regulation. Many counter-regulatory hormones show a reduced response after antecedent hypoglycaemia. We therefore investigated whether this decrease in responsiveness with repetitive hypoglycaemia also pertains to VEGF.

METHODS

Three hypoglycaemic clamp experiments were performed on two consecutive days in 15 healthy men. VEGF response was assessed during the first and last hypoglycaemic period.

RESULTS

As expected, plasma VEGF concentrations rose markedly during the clamps (P < 0.001). The increase was distinctly blunted during the third (+13 +/- 8 pg/ml) as compared with the first (+54 +/- 18 pg/ml) hypoglycaemic clamp (P = 0.046).

CONCLUSION

This data confirms that circulating VEGF concentrations increase acutely during hypoglycaemia. Like the counter-regulatory hormones, the hypoglycaemia-induced rise in VEGF is attenuated after antecedent hypoglycaemia. The origin of increased systemic VEGF concentration during hypoglycaemia and its physiological role remains to be defined.

New insights into MLL gene rearranged acute leukemias using gene expression profiling: shared pathways, lineage commitment, and partner genes

Rearrangements of the MLL gene occur in both acute lymphoblastic and acute myeloid leukemias (ALL, AML). This study addressed the global gene expression pattern of these two leukemia subtypes with respect to common deregulated pathways and lineage-associated differences. We analyzed 73 t(11q23)/MLL leukemias in comparison to 290 other acute leukemias and demonstrate that 11q23 leukemias combined are characterized by a common specific gene expression signature. Additionally, in unsupervised and supervised data analysis algorithms, ALL and AML cases with t(11q23) segregate according to the lineage they are derived from, that is, myeloid or lymphoid, respectively. This segregation can be explained by a highly differing transcriptional program. Through the use of novel biological network analyses, essential regulators of early B cell development, PAX5 and EBF, were shown to be associated with a clear B-lineage commitment in lymphoblastic t(11q23)/MLL leukemias. Also, the influence of the different MLL translocation partners on the transcriptional program was directly assessed. Interestingly, gene expression profiling did not reveal a clear distinct pattern associated with one of the analyzed partner genes. Taken together, the identified molecular expression pattern of MLL fusion gene samples and biological networks revealed new insights into the aberrant transcriptional program in 11q23/MLL leukemias.

Prognostic impact of RT-PCR-based quantification of WT1 gene expression during MRD monitoring of acute myeloid leukemia

In search for general PCR targets for minimal residual disease (MRD) studies in acute myeloid leukemia (AML), Wilms' tumor gene 1 (WT1) expression was assessed by real-time RT-PCR relative to the control gene ABL in 569 archived samples of AML patients (pts). Pts were analyzed at diagnosis (n=116) and during follow-up (n=105, median 4 times, range 2--17). Median follow-up time was 258 days (range 16--1578 days). In 66 pts, the WT1 expression was analyzed in comparison to a second PCR marker or to multiparameter flow cytometry. Quantitative WT1 levels correlated to the clinical course or a second marker in 83-96% of the cases. Prognostic significance of WT1 levels was analyzed at diagnosis and three intervals: (1) days 16--60, (2) days 61--120, and (3) days 121--180 after start of chemotherapy. Higher levels of WT1 expression were associated with shorter overall survival (OS) and event-free survival (EFS) within intervals 2 and 3 but not at diagnosis or interval 1. In addition, within these intervals, WT1/ABL levels <or=0.4% were associated with improved OS and EFS. An increase of WT1 levels was detected in 16/44 cases, which subsequently relapsed within a median of 38 days (range 8--180 days). In conclusion, quantification of WT1 may be used for MRD studies and for prognostification in AML.