BioProject

Purpose: Accurate prediction of clinical response is the prerequisite for individualized therapy in chronic lymphocytic leukemia (CLL). More...

Purpose: Accurate prediction of clinical response is the prerequisite for individualized therapy in chronic lymphocytic leukemia (CLL). We hypothesized that sequential assessment of gene expression changes early during therapy may well reflect behaviour of the leukemic clone in response to specific drugs. Patients and Methods: Gene expression profiles (GEP) were determined in CD19+ selected B-cells from 20 patients treated with fludarabine and cyclophosphamide (FC) (N=10) or FC plus rituximab (FCR) (N=10). Samples were collected in the first cycle before and within 48hours after initiation of treatment. GEP analysis was stratified by clinical response 3 months after start of therapy. Results: GEP before treatment detected high expression of 34 genes correlated with response and 32 genes correlated with resistance to therapy. These genes were related to regulation of apoptosis, cell cycle, cell adhesion, and signal transduction. Different results were obtained with sequential GEP: Sixteen genes were up-regulated after rituximab infusion in non-responders. Rituximab therapy resulted in down-regulation of AKT1 indicating involvement of the PI3-kinase pathway in CD20-signaling. Up-regulation of 24 genes after FC (including ITPKB (inositol 1,4,5-trisphosphate 3-kinase) and CD44) and of 36 genes after FCR (including CD49d) was associated with resistance. Down-regulation of CTLA4 correlated with poor response to FC. CD44, CD49d and the PI3-kinase signaling pathway were confirmed as potential therapeutic targets to overcome resistance by (protein analysis) or functional experiments. Conclusion Sequential GEP provides rapid and relevant information for prediction of response and resistance. This approach could be used to guide and adapt individualized therapy in CLL. Overall design: 50 Samples from CD19 selected B-cells, three treatments (rituximab, FC and RFC), 10 replicates for each treatment, 20 replicates for control condition Less...