Clinical and molecular characterization of diffuse large B-cell lymphomas with 13q14.3 deletion.

Background: Deletions at 13q14.3 are common in chronic lymphocytic leukemia and are also present in diffuse
large B-cell lymphomas (DLBCL) but never in immunodeficiency-related DLBCL. To characterize DLBCL with 13q14.3
deletions, we combined genome-wide DNA profiling, gene expression and clinical data in a large DLBCL series treated
with rituximab, cyclophosphamide, doxorubicine, vincristine and prednisone repeated every 21 days (R-CHOP21).
Patients and methods: Affymetrix GeneChip Human Mapping 250K NspI and U133 plus 2.0 gene were used.
MicroRNA (miRNA) expression was studied were by real-time PCR. Median follow-up of patients was 4.9 years.
Results: Deletions at 13q14.3, comprising DLEU2/MIR15A/MIR16, occurred in 22/166 (13%) cases. The deletion
was wider, including also RB1, in 19/22 cases. Samples with del(13q14.3) had concomitant specific aberrations. No
reduced MIR15A/MIR16 expression was observed, but 172 transcripts were significantly differential expressed.
Among the deregulated genes, there were RB1 and FAS, both commonly deleted at genomic level. No differences in
outcome were observed in patients treated with R-CHOP21.
Conclusions: Cases with 13q14.3 deletions appear as group of DLBCL characterized by common genetic and
biologic features. Deletions at 13q14.3 might contribute to DLBCL pathogenesis by two mechanisms: deregulating the
cell cycle control mainly due RB1 loss and contributing to immune escape, due to FAS down-regulation.