Impact of cytogenetic and molecular prognostic markers on the clinical management of chronic lymphocytic leukemia

Abstract

© F e r r a t a S t o r t i F o u n d a t i o nsubgroups for further analysis in microarray studies. Gene expression profiling revealed the association of a number of genes previously thought to be unrelated to CLL. Depending on the use of CD19-selected/T-cell depleted or unpurified B-CLL samples, a variety of markers have been found since the initial experiments of Klein and Rosenwald in 2001. 19,52-54 A comprehensive analysis of more than 500 patients suggests a complex expression pattern with many CLL subgroups and overlaps.55 Furthermore, Fernàndez et al. have shown considerable intra-individual modulation of gene expression patterns during the course of disease. 56The first established marker emerging from microarray analysis was the receptor kinase ZAP-70. The prognostic value of this genetic marker has now been well established by FACS-analysis or PCR.33,34,57-62 ZAP-70 protein expression predicts for treatment-free survival (TFS) and overall survival independently of mutation status. While convincing results were obtained by several groups using different protein detection methods, efforts by the European Initiative in CLL Research (ERIC) to standardize their study approach have proved problematic.63 Furthermore, investigations into the association with IgVH mutational status have yielded differing results, particularly 17p-samples cluster in the ZAP-70 negative group.64 Assessment of ZAP-70 mRNA expression by real time PCR requires positive (CD19) or negative selection of B-cells. 33,34 Despite these drawbacks, ZAP-70 is a useful clinical marker and may also serve as a future target for specific signal transduction inhibitors.Among the markers with an even stronger correlation to IgVH mutational status, 52,53 lipoprotein lipase has been extensively studied. [35][36][37][38][39][40] Its association with other markers (cytogenetic risk groups, molecular markers) as well as patient outcome (time to treatment, overall survival) is also strong. Lipoprotein lipase is a stable marker which has been studied by real-time PCR in several large series using purified or unpurified CLL cells or even whole blood. No difference between purified and unpurified samples was observed in several studies, indicating its potential for easy and general use. Its specificity regarding IgVH mutational status is 89%, with a sensitivity of 68%, a positive predictive value of 83% and a negative predictive value of 78%.39 Discordant results are also observed.36 Lipoprotein lipase can be combined with a downregulated marker (ADAM29) to increase specificity.35 While lipoprotein lipase protein can also be detected on normal B-cells, its cytoplasmatic expression correlates well with RNA levels. 36 We have used the level of lipoprotein lipase-expression as a discriminator for microarray analysis.19 Several markers emerging from this experiment have been validated by real time PCR. Among those, septin 10 and dystrophin (DMD) were strongly associated with time to treatment. The prognostic significance of some of these factors have also be...

p53 flow cytometry evaluation in leukemias: Correlation to factors affecting clinical outcome

“…In this disease, chromosomal structural alterations as 17p deletion and point mutation of p53 gene have been reported in 10-15% of cases (6). These genetic abnormalities have been associated with poor survival and failure to therapy and they were reported in patients with transformation to Richter's syndrome, suggesting that p53 alterations play a role in this clinical adverse outcome (7,38). In addition, these genetic alterations result in poor response to fludarabine, a drug frequently used in CLL treatment (38).…”

“…These genetic abnormalities have been associated with poor survival and failure to therapy and they were reported in patients with transformation to Richter's syndrome, suggesting that p53 alterations play a role in this clinical adverse outcome (7,38). In addition, these genetic alterations result in poor response to fludarabine, a drug frequently used in CLL treatment (38). The analysis of patients with CLL revealed that 14 of 64 patients with CLL had increased levels of p53 protein expression including eight of nine that progressed to Richter's syndrome.…”

“…Unfortunately, these systems fail to identify patients in early stages whose disease will rapidly progress. In recent years, numerous biological approaches have been provided new prognostic markers such as CD38, ZAP-70 and detection of p53 alterations (14,38). In this disease, chromosomal structural alterations as 17p deletion and point mutation of p53 gene have been reported in 10-15% of cases (6).…”

Sequential gene expression profiling during treatment for identification of predictive markers and novel therapeutic targets in chronic lymphocytic leukemia

“…Importantly, the aberrant COX-2 expression is associated with disease progression suggesting a role in the malignant transformation. 4 In normal cells, COX-2 is an inducible key factor in prostaglandin synthesis and mediates inflammation by increased levels of prostaglandin. Ectopic expression of COX-2 and its downstream partner microsomal prostaglandin E synthase-1 (mPGES1) has been implicated in the pathogenesis of several cancer types, and the resulting production of prostaglandin E 2 (PGE 2 ) is known to sustain cancer progression by promotion of angiogenesis, invasion and metastasis.…”

“…So far, gene expression profiling (GEP) in vivo in CLL was mainly used in a cross-sectional approach by studying patient samples before treatment. 4 We applied a sequential GEP (sGEP) approach to investigate the gene expression signature of CD19 þ selected CLL cells before and after treatment in vivo. This was complemented by protein analysis as well as by functional in vitro analysis of selected targets.…”