Association between molecular lesions and specific B-cell receptor subsets in chronic lymphocytic leukemia

CD49d is overexpressed by trisomy 12 chronic lymphocytic leukemia cells: evidence for a methylation-dependent regulation mechanism

CD49d, a negative prognosticator with a key role for microenvironmental interactions in CLL, is near universally expressed in trisomy 12 CLL. CD49d overexpression in trisomy 12 CLL is regulated by a methylation-dependent mechanism.

Molecular bases of chronic lymphocytic leukemia in light of new treatments

The human genome era heralded a fundamental progress in the field of cancer genetics that shifted from a candidate gene approach toward global views of genomes and transcriptomes. Whole genome/exome sequencing has disclosed the genetic landscape of several hematologic tumors, providing comprehensive catalogs of somatic mutations and new insights into the genes that contribute to cellular transformation. Thanks to these technical progresses, research on the molecular pathogenesis of chronic lymphocytic leukemia (CLL) has also advanced at a sustained pace in recent times revealing NOTCH1, SF3B1, BIRC3, and MYD88 as the most recurrently (>5%) mutated genes that have been identified in CLL. Beside mutations of cancer related genes, another mechanism involved in disease initiation and progression of mature B-cell tumors, including CLL, is represented by B cell receptor (BCR) signaling. The BCR plays a central role in disease pathogenesis and, consequently, BCR signaling might represent a suitable target for therapy in many patients. Currently, the Bruton tyrosine kinase (BTK) inhibitor ibrutinib, which acts downstream the BCR signaling pathway, appears to be particularly promising and shows important clinical activity in CLL.

Temporal dynamics of clonal evolution in chronic lymphocytic leukemia with stereotyped IGHV4-34/IGKV2-30 antigen receptors: longitudinal immunogenetic evidence

Chronic lymphocytic leukemia (CLL) patients assigned to stereotyped subset 4 possess distinctive patterns of intraclonal diversification (ID) within their immunoglobulin (IG) genes. Although highly indicative of an ongoing response to antigen(s), the critical question concerning the precise timing of antigen involvement is unresolved. Hence, we conducted a large-scale longitudinal study of eight subset 4 cases totaling 511 and 398 subcloned IG heavy and kappa sequences. Importantly, we could establish a hierarchical pattern of subclonal evolution, thus revealing which somatic hypermutations were negatively or positively selected. In addition, distinct clusters of subcloned sequences with cluster-specific mutational profiles were observed initially; however, at later time points, the minor cluster had often disappeared and hence not been selected. Despite the high intensity of ID, it was remarkable that certain residues remained essentially unaltered. These novel findings strongly support a role for persistent antigen stimulation in the clonal evolution of CLL subset 4.