Articles
Chronic Lymphocytic Leukemia
274haematologica | 2013; 98(2)
IntroductionChronic lymphocytic leukemia (CLL) is a heterogeneous disease with a highly variable outcome depending on clinical and biological characteristics. Clinical staging is a relatively simple method of assessing the outcome of CLL patients based on clinical parameters.1,2 In the last two decades, multiple biological markers have been shown to have prognostic relevance in CLL, most notably chromosomal aberrations, IGHV mutations and expression of surface markers such as ZAP-70 and CD38. [3][4][5][6][7][8] Gene expression analyses have also revealed the heterogeneity of CLL, with distinct gene expression signatures being associated with particular genetic subgroups of CLL. [9][10][11] In particular, the expression of genes such as CLLU1, ADAM29 and LPL have recently been associated with different outcomes in CLL. [12][13][14][15][16][17] CLLU1 located at chromosome 12q22, encodes a novel transcript, which has been identified as a marker specific to CLL. 18 In particular, high CLLU1 expression (CLLU1-H) is significantly more frequent in unmutated IGHV and CD38 + CLL. 19,20 CLLU1-H has been shown to be associated with shorter overall survival and shorter time to first treatment in patients with early stage CLL, 20 especially those younger than 70 years. 13 In addition, CLLU1 expression has been shown to be a specific and stable marker in CLL cells, 21 making it a promising marker not only for prognosis but also for minimal residual disease analysis. 22 However, the effect of CLLU1 expression on response to therapy is currently unknown and, to date, there are no data on the significance of CLLU1 expression with regards to progression-free survival and overall survival in patients receiving first-line therapy. We assessed the value of CLLU1 expression as a prognostic marker in the LRF CLL4 randomized controlled trial.
Design and Methods
Patients and samplesPre-treatment blood samples were collected at the time of entry into the trial and were available for CLLU1 expression analysis from 515 of the 777 patients. The patients were previously untreated, 25% having Binet stage A-progressive disease, 45% stage B and 30% stage C. The male:female ratio was 3:1 and the median age was 65 years (range, 35-86 years). Patients were randomized to receive chlorambucil, fludarabine, or fludarabine with cyclophosphamide. The trial was approved by a multicenter research ethics committee and all patients gave informed consent.
RNA extraction and CLLU1 expression analysisRNA was extracted using the RNeasy Mini Kit (Qiagen) after which ©2013 Ferrata Storti Foundation. This is an open-access paper. doi:10.3324/haematol.2012.070201 DG and ME contributed CLLU1, located at chromosome 12q22, encodes a transcript specific to chronic lymphocytic leukemia and has potential prognostic value. We assessed the value of CLLU1 expression in the LRF CLL4 randomized trial. Samples from 515 patients with chronic lymphocytic leukemia were collected immediately before the start ...