Genetic Heterogeneity and Evolution in Lymphoid Malignancies

Patterns of mutation and clonal evolution in relapsed acute lymphoblastic leukemiaRelapsed acute lymphoblastic leukemia remains a major cause of childhood cancer death, and this remains true despite the advent of new targeted and immunotherapeutic approaches. Recent years have witnessed the use of broad and deep serial genomic profiling approaches to dissect the relationship of genetic variegation to clonal evolution and relapse. Studies of over 90 children treated on St Jude Total Therapy protocols, incorporating genome, exome and transcriptome sequencing, coupled with limiting dilution xenografting to formally elucidate clonal structure have provided multiple key insights. In the majority of cases, the relapse-fated clone is a minor clone at diagnosis, that harbors resistance-enriched (and thus relapse-promoting) mutations at diagnosis, and/or acquires additional mutations the confer resistance after initial therapy. Approximately one third of cases relapse from a major clone, or show polyclonal evolution, and such cases typically have a shorter time to disease recurrence and relapse. A subset of cases exhibit complete discordance for somatic non-silent mutations, DNA copy number alterations and antigen receptor rearrangements between diagnosis and relapse, suggesting relapse represents a second leukemia; however such cases typically preserve the founding chromosomal rearrangement and a subset of non-coding mutations, indicating that relapse arises from an ancestral clone t...
Source: Blood - Category: Hematology Authors: Tags: Role and Mechanisms of Clonal Evolution in Lymphoid Malignancies Source Type: research