Gene expression profiles of 16 relapsed/refractory CLL patients treated with lenalidomide in a phase II clinical trial

The aim of the study is to identify differentially expressed genes between chronic lymphocytic leukemia (CLL) patients who will respond to lenalidomide treatment and non responsive patients. We performed a whole genome gene-expression analysis of pre-treatment samples collected from 16 CLL patients included in a phase II clinical trial. The pre-treatment sample comprises purified CD19 cells from peripheral blood. Ten (37%) patients achieved partial responses (PR) and were classified as responders (R), 2 (7%) stable diseases (SD) and 4 (15%) progressive diseases (PD) and were classified as non responders (NR). Supervised analysis identified 78 genes up-regulated and 119 genes down-regulated in R compared with NR (Fold change [FC]≥2, p<0.01, Figure 4). Different expression levels of genes involved in interferon (INF) and Wnt signaling pathways characterized patients who will respond to lenalidomide. In particular, R showed a 23-fold increase in Wnt inhibitor Shisa homolog 3 (SHISA3), whereas a decrease of WISP3, CDH4, HOXB7 and WNT10A. Moreover, leukemic cells collected from R down-regulated interferon-induced proteins (IFI44, -6.6; IFI44L, -9.3; IFIT2, -2) and STAT1 (-2.4 fold change). NR group up-regulated lipoprotein lipase (LPL, +7.5). The baseline expression levels of cereblon (CRBN) were not dissimilar between R and NR subsets Large-scale gene expression profiling (GEP) was performed on total RNA extracted from purified CD19+ CLL cells (RNeasy Mini kit Plus, QIAGEN, Valencia, CA, USA) from 16 individual CLL patients by hybridization on 4X44K Whole Human Genome Microarray (Agilent Technologies, Palo alto, CA). Fluorescence data were analysed with Feature Extraction Software v.10.5 (Agilent Technologies) an QC Chart tool v.1.3. Agglomerative two-dimensional clustering analysis and supervised analyses based on t-test were performed using Gene Spring GX (Agilent) software. Genes were defined as differentially expressed between groups at a significant level of p<0.05 and with a fold change cut off ± 2 in all the pair wise comparisons.