Chronic lymphocytic leukemia patients with <scp><i>IGH</i></scp> translocations are characterized by a distinct genetic landscape with prognostic implications

Abstract

Chromosome 14q32 rearrangements/translocations involving the immunoglobulinheavy chain (IGH) are rarely detected in chronic lymphocytic leukemia (CLL). Theprognostic significance of the IGH translocation is controversial and its mutational profile remains unknown. Here, we present for the first time a comprehensive next-generation sequencing (NGS) analysis of 46 CLL patients with IGH rearrangement(IGHR-CLLs) and we demonstrate that IGHR-CLLs have a distinct mutational profilewith recurrent mutations in BRAF and HIST1H1E genes. Interestingly, BCL2 and FBXW7mutations were significantly associated with this subgroup and almost half of BCL2, IGLL5 and HISTH1E mutations reported were previously identified in non-Hodgkin lymphomas. Notably, IGH/BCL2 rearrangements were associated with a lower mutation frequency and carried BCL2 and IGLL5 mutations, while the other IGHR-CLLs had mutations in genesrelated to poor prognosis (NOTCH1, SF3B1 and TP53) and shorter time to first treat-ment (TFT). Moreover, IGHR-CLLs patients showed a shorter TFT than CLL patients carrying 13q−, normal fluorescence in situ hybridization (FISH) and +12 CLL, NOTCH1, SF3B1, TP53, BIRC3 and BRAF werealso mutated. The presence of these mutations not only was an independent risk fac-tor within IGHR-CLLs, but also refined the prognosis of low-risk cytogenetic patients(13q−/normal FISH). Hence, our study demonstrates that IGHR-CLLs have a distinct mutational profile from the majority of CLLs and highlights the relevance of incorporating NGS and the status ofIGHby FISH analysis to refine the risk-stratification CLL model.