Clinical impact of leukemic blast heterogeneity at diagnosis in cytogenetic intermediate-risk acute myeloid leukemia.

BACKGROUND: Individual cellular heterogeneity within the acute myeloid leukemia (AML) bone marrow samples can be observed by multi parametric flow cytometry analysis (MFC) indicating that immunophenotypic screening for leukemic blast subsets may have prognostic impact. MATERIAL AND METHODS: Samples from de novo AML patients of all cytogenetic risk groups were collected at diagnosis and subjected to MFC based on a four-color antibody panels against 33 CD membrane markers and retrospectively analyzed for the leukemia blast expression pattern and mean fluorescence intensity. Identification of the leukemic blast cells was based on right angle light scatter (SSC) and expression of CD45 and the cellular heterogeneity identified by the presence of at least two distinct subsets by any CD marker. RESULTS: Analysis of marrow samples from 86 patients with cytogenetic intermediate risk identified recurrent heterogeneous blast phenotypes for selected CD markers, three of which had prognostic impact with loss or gain of CD58, CD117, or CD14 expression. Multivariate Cox regression analysis of diagnostic variables identified poor prognostic factors: Age >55 years, presence of extramedullary disease, WHO performance score >2, a heterogeneous CD58, CD117, or CD14 expression on blast cells. Each variable added to a simple and clinical useful and MFC based prognostic score system associated to inferior survival in the intermediate risk group of AML patients. CONCLUSIONS: These observations support that leukemic blast heterogeneity detected by MFC has additional prognostic significance in de novo AML; however, the score system needs to be prospectively validated in future clinical trials before implementation.

GFR prediction from cystatin C and creatinine in children: effect of including body cell mass.

BACKGROUND: Aiming to develop a more accurate cystatin C-based model for estimation of glomerular filtration rate (GFR) in children, we hypothesized that inclusion of body cell mass (BCM) would increase the accuracy of the GFR estimate in comparison to a well-established GFR reference method. STUDY DESIGN: Diagnostic test accuracy study. SETTINGS & PARTICIPANTS: 119 children (mean age, 8.8; range, 2.3-14.9 years) referred for GFR measurement by chromium 51 ethylenediaminetetraacetic acid ((51)Cr-EDTA) clearance (mean GFR, 98; range, 13.7-147.4 mL/min/1.73 m(2)). INDEX TEST: GFR estimations by the 2 prediction models resulting from theoretical considerations corroborated by forward stepwise variable selection: GFR (mL/min) = 0.542 × (BCM/SCysC)(0.40) × (height × BSA/SCr)(0.65) and GFR (mL/min) = 0.426 × (weight/SCysC)(0.39) × (height × BSA/SCr)(0.64), where SCysC is serum cystatin C level, BSA is body surface area, and SCr is serum creatinine level. The accuracy and precision of these models were compared with 7 previously published prediction models using random subsampling cross-validation. Local constants and coefficients were calculated for all models. Root mean square error, R(2), and percentage of predictions within ±10% and ±30% of the reference GFR were calculated for all models. Based on 1,000 runs of the cross-validation procedure, median values and 2.5th and 97.5th quantiles of the validation parameters were calculated. REFERENCE TEST: GFR measurement by (51)Cr-EDTA clearance. RESULTS: The BCM model predicted 98% within ±30% of reference GFR and 66% within ±10%, which was higher than for any other model. The weight model predicted 97.5% within ±30% of reference GFR and 62% within ±10%. The BCM model had the highest R(2) and the smallest root mean square error. LIMITATIONS: Included only 9 children with GFR <60 mL/min/1.73 m(2). Lack of independent validation cohort. CONCLUSIONS: The novel BCM model predicts GFR with higher accuracy than previously published models. The weight model is almost as accurate as the BCM model and allows for GFR estimation without knowledge of BCM. However, endogenous methods are still not sufficiently accurate to replace exogenous markers when GFR must be determined with high accuracy.

Multiparametric flow cytometry for identification and fluorescence activated cell sorting of five distinct B-cell subpopulations in normal tonsil tissue.

The purpose of this study was to establish a procedure capable of isolating distinct B-cell subpopulations from human tonsils as a basis for subsequent molecular analyses. Overall, 5 distinct B-cell subpopulations were purified from fresh tonsils based on their fluorescence surface marker expression: naive B cells, centroblasts, centrocytes, memory B cells, and plasmablasts. The immunophenotypic identity of the subpopulations was verified by quantitative real-time reverse transcriptase-polymerase chain reaction using the proliferation marker MKI-67 and 6 B-cell-associated differentiation markers (BACH2, BCL6, PAX5, IRF4, PRDM1, and XBP1). Furthermore, within the centroblast compartment, large and small centroblasts could be distinguished and large centroblasts were shown to proliferate with a morphologic appearance of a "centroblast"-like cell but with lower gene expression of the germinal center markers BCL6 and BACH2 vs small centroblasts. This study has established a detailed and fast procedure for simultaneous sorting of up to 5 distinct maturation-associated B-cell subpopulations from human tonsils.

Generation of a predictive melphalan resistance index by drug screen of B-cell cancer cell lines.

BACKGROUND: Recent reports indicate that in vitro drug screens combined with gene expression profiles (GEP) of cancer cell lines may generate informative signatures predicting the clinical outcome of chemotherapy. In multiple myeloma (MM) a range of new drugs have been introduced and now challenge conventional therapy including high dose melphalan. Consequently, the generation of predictive signatures for response to melphalan may have a clinical impact. The hypothesis is that melphalan screens and GEPs of B-cell cancer cell lines combined with multivariate statistics may provide predictive clinical information. MATERIALS AND METHODS: Microarray based GEPs and a melphalan growth inhibition screen of 59 cancer cell lines were downloaded from the National Cancer Institute database. Equivalent data were generated for 18 B-cell cancer cell lines. Linear discriminant analyses (LDA), sparse partial least squares (SPLS) and pairwise comparisons of cell line data were used to build resistance signatures from both cell line panels. A melphalan resistance index was defined and estimated for each MM patient in a publicly available clinical data set and evaluated retrospectively by Cox proportional hazards and Kaplan-Meier survival analysis. PRINCIPAL FINDINGS: Both cell line panels performed well with respect to internal validation of the SPLS approach but only the B-cell panel was able to predict a significantly higher risk of relapse and death with increasing resistance index in the clinical data sets. The most sensitive and resistant cell lines, MOLP-2 and RPMI-8226 LR5, respectively, had high leverage, which suggests their differentially expressed genes to possess important predictive value. CONCLUSION: The present study presents a melphalan resistance index generated by analysis of a B-cell panel of cancer cell lines. However, the resistance index needs to be functionally validated and correlated to known MM biomarkers in independent data sets in order to better understand the mechanism underlying the preparedness to melphalan resistance.

Efficacy of routine surveillance with positron emission tomography/computed tomography in aggressive non-Hodgkin lymphoma in complete remission: status in a single center.

Post-therapy surveillance imaging in patients with lymphoma remains controversial. We report our experience with positron emission tomography/computed tomography (PET/CT) surveillance in patients with aggressive non-Hodgkin lymphoma in first complete remission (CR). The 138 PET/CTs performed in 52 patients revealed four unsuspected relapses. In one patient, relapse was visualized by fluorodeoxyglucose (FDG) accumulation without any significant CT pathology. The specificity and sensitivity of surveillance PET/CT were 89% and 100%, respectively. The predictive values of positive and negative PET/CTs were 21% and 100%, respectively. The cost of half-yearly routine PET/CT surveillance during the first 2 years in CR was $US8552 per patient and accounted for 81% of the total follow-up costs. PET/CT was effective in detecting unexpected relapse and normal PET/CT supported continuous CR. However, the impact of PET/CT was limited by the high number of false-positive results and PET/CT surveillance was costly compared to CT surveillance.

European Myeloma Network: the 3rd Trialist Forum Consensus Statement from the European experts meeting on multiple myeloma.

Over the past two decades, not only treatment options, but also the diagnosis, staging, and risk assessment of multiple myeloma (MM), have undergone significant development, partially due to a deeper understanding of MM pathogenesis. Conventional cytogenetics and fluorescence in situ hybridization are routinely assessed in MM, and when combined with ISS stage may attain an even better predictive potential. In order to achieve even more effective and individualized therapies, one crucial goal is the identification of genes and gene combinations that predict for response or resistance to chemotherapy. High-dose chemotherapy with autologous stem cell transplant (SCT) still remains the standard therapy for younger patients, with novel agents now being included in both pre-transplant regimens and post-transplant consolidation/maintenance approaches. Similarly, novel agents are also being incorporated into allogeneic SCT for selected patients. In the treatment of elderly patients with MM, novel agents have been successfully incorporated into less intensive regimens, including melphalan/prednisone, low-dose dexamethasone, and cyclophosphamide/dexamethasone. While second-generation proteasome inhibitors are currently being intensively investigated, the subcutaneous administration of bortezomib, being equivalent to the established i.v. route, is now entering clinical practice. Supportive care remains a crucial aspect in the management of MM. The European Myeloma Network Trialist Group aims to address these contemporary aspects in MM.

Improved survival for multiple myeloma in denmark based on autologous stem cell transplantation and novel drug therapy in collaborative trials: analysis of accrual, prognostic variables, selection bias, and clinical behavior on survival in more than 1200 patients in trials of the nordic myeloma study group.

BACKGROUND: An unexplained survival difference was observed in the Nordic Myeloma Study Group (NMSG) high-dose therapy trial 5/94 in Denmark compared with Sweden and Norway; however, this difference was eliminated in the subsequent NMSG trial 7/98. It was hypothesized that a detailed analysis of potential explanations would reveal important information for future designs of clinical trials for multiple myeloma (MM) patients in Denmark. PATIENTS AND METHODS: The analysis is based on 3 consecutive clinical trials coordinated by NMSG from 1990 to 2000: NMSG 4/90 including 583 patients, NMSG 5/94 including 274 patients and NMSG 7/98 including 414 patients with newly diagnosed MM. Event-free and total survival rates were calculated according to the Kaplan-Meier method, and survival comparisons were made by the log-rank test. The Cox proportional hazards regression model was used to estimate the prognostic importance of selected variables. RESULTS: The analysis revealed no differences in disease stages, prognostic variables, or inclusion bias at diagnosis between the 3 consecutive NMSG trials. However, the number of initial treatment failures was low, and post-relapse survival was superior in Swedish patients as compared to Danish patients. These differences were explained by a defensive clinical practice in Denmark during 1994-1997 for patients with poor risk refractory or relapsed disease. CONCLUSION: These initially observed differences were subsequently eliminated most likely as a consequence of international collaboration improving diagnosis, research infrastructure, clinical training, and education as planned within the European Myeloma Network (EMN).

Cancer stem cells and the cellular hierarchy in haematological malignancies.

Malignancies in the haematopoietic system seem to depend on a small subset of so-called cancer stem cells (CSC) for their continued growth and progression - this was first described as the "sleeper-feeder theory" for leukaemia. The leukaemia stem cell was the first of such subsets to be described although the origins of these cells have been difficult to dissect. Consequently, their biology is not fully elucidated, which also holds true for the normal-tissue counterparts. The stem cell concept describes stem cells to be of low frequency, self renewing and with multilineage potential based on phenomenology - a definition which may not hold strictly true for CSCs when studied in animals and humans in vivo and in vitro. Several studies have analysed the cellular hierarchy of the haematopoietic system by cell sorting of few and even single cells, tracking acquired genetic changes and performing transplantation model studies to document subsets within the differentiating hierarchy as potential CSC compartments. In leukaemia the CSC has been described in the bone marrow compartment of haematopoietic stem cells (HSC); however, in other bone marrow disorders like multiple myeloma it is likely that the cell of origin is a more differentiated cell, like post-germinal memory B cells or plasmablasts. Studies performed so far have even indicated that the genetic events may occur in different B cell subsets in accordance with the stepwise oncogenesis of the disease. Although our understanding of the nature and biology of these initiating cells remains unknown, the obvious existence of such cells has implications for understanding initial malignant transformation and disease metastasis or progression and, most important, the selection of individualised therapeutic strategies targeting the subsets harbouring the CSC function. In the present review on stem cells in haematological malignancies we have focused on two topics, first, describing the stem cell concept in health and disease, and its "phenomenology", and second, describing the CSC compartments in leukaemia and multiple myeloma.