Array comparative genomic hybridization reveals genomic copy number changes associated with outcome in diffuse large B-cell lymphomas.

Abstract

To identify, in high-resolution regions of DNA, the copy number changes associated with outcome in patients with diffuse large B-cell lymphoma (DLBCL), a disease with an approximately 50% mortality rate, we performed array comparative genomic hybridization (array-CGH) on specimens from 64 patients with newly diagnosed DLBCL treated with anthracycline-based chemotherapy. For the entire cohort, 55 commonly gained/lost regions, ranging in size from less than 1 Mbp to entire chromosomes, were identified using 1- to 2-Mbp and 2- to 4-Mbp resolution BAC arrays. Copy number changes of 9 minimal regions significantly correlated with overall survival, of which 6 were 10 Mbp or smaller. On multivariate analysis, loss of chromosomes 2 (2.4-4.1 Mbp) and 16 (33.8-35.6 Mbp) were found to be prognostic indicators of poor survival, independent of clinical features routinely used to predict outcome. Loss of chromosome 1 (78.2-79.1 Mbp) was predictive of good outcome. For a subset of 55 specimens classified according to cell-of-origin expression signature subtype, gain of chromosome 12 (45.4-53.8 Mbp) was found to be significantly associated with the germinal center B-cell-like DLBCL subtype. Overall, array-CGH identified relatively small genomic regions associated with outcome, which, along with follow-up expression studies, may reveal target genes important in DLBCL clinical behavior.