RESUMO
The t(14;19)(q32;q13) often juxtaposes BCL3 with immunoglobulin heavy chain (IGH) resulting in overexpression of the gene. In contrast to other oncogenic translocations, BCL3 rearrangement (BCL3-R) has been associated with a broad spectrum of lymphoid neoplasms. Here we report an integrative whole-genome sequence, transcriptomic, and DNA methylation analysis of 13 lymphoid neoplasms with BCL3-R. The resolution of the breakpoints at single base-pair revealed that they occur in two clusters at 5' (n=9) and 3' (n=4) regions of BCL3 associated with two different biological and clinical entities. Both breakpoints were mediated by aberrant class switch recombination of the IGH locus. However, the 5' breakpoints (upstream) juxtaposed BCL3 next to an IGH enhancer leading to overexpression of the gene whereas the 3' breakpoints (downstream) positioned BCL3 outside the influence of the IGH and were not associated with its expression. Upstream BCL3-R tumors had unmutated IGHV, trisomy 12, and mutated genes frequently seen in chronic lymphocytic leukemia (CLL) but had an atypical CLL morphology, immunophenotype, DNA methylome, and expression profile that differ from conventional CLL. In contrast, downstream BCL3-R neoplasms were atypical splenic or nodal marginal zone lymphomas (MZL) with mutated IGHV, complex karyotypes and mutated genes typical of MZL. Two of the latter four tumors transformed to a large B-cell lymphoma. We designed a novel fluorescence in situ hybridization assay that recognizes the two different breakpoints and validated these findings in 17 independent tumors. Overall, upstream or downstream breakpoints of BCL3-R are mainly associated with two subtypes of lymphoid neoplasms with different (epi)genomic, expression, and clinicopathological features resembling atypical CLL and MZL, respectively.
Assuntos
Leucemia Linfocítica Crônica de Células B , Linfoma Difuso de Grandes Células B , Humanos , Leucemia Linfocítica Crônica de Células B/genética , Hibridização in Situ Fluorescente , Translocação Genética , Rearranjo Gênico , Linfoma Difuso de Grandes Células B/genética , Cadeias Pesadas de Imunoglobulinas/genética , Cromossomos Humanos Par 14/genéticaRESUMO
Fludarabine-cyclophosphamide-rituximab (FCR) has been the gold standard front-line treatment for fit CLL patients until novel agent's introduction. Decision between either time-limited FCR or "endless" Bruton's tyrosine kinase inhibitor (BTKi) therapy may be difficult in fit IGHV-mutated-non-TP53 cases. We describe the outcomes after front-line FCR in 110 CLL patients from 5 centres in Catalonia, Spain, over a period of more than 10 years. ORR was 96.3% and CR 74.5%. Median second-treatment free survival (TFS1) was 6.2 years and median OS was 10.8 years. 50 (45.5%) patients required a subsequent therapy. Median third-treatment free survival was better for BTKi than for chemotherapy ± antiCD20 strategies (not reached vs 3.1 years, p = 0.003). Only 50 (45.5%) patients completed 6 cycles of FCR, and the main reason for discontinuation was cytopenia 29 (26.4%). 15 (13.6%) patients developed a second cancer, and 5 (4.5%) patients experienced a Richter's transformation (RT). At the end of follow-up, 50 (45.5%) patients remained in CR. Response rates, TFS1, OS, RT, and second cancers did not differ between patients treated with 6 vs 4 cycles of FCR. In conclusion, front-line FCR treatment leads to very long CR in almost half of patients, and BTKi yields excellent outcomes in relapsed patients.