Chronic lymphocytic leukemia (CLL), the most common leukemia in adults, has consistently been at the forefront of genomic discovery. The two major subtypes of CLL are distinguished by the level of mutation in their immunoglobulin IGHV gene, which reflects the maturation level of their B-cell of origin. Despite prior advances, we lack a comprehensive molecular map of CLL that could explain the high variability in patient outcome and provide a roadmap towards precision medicine. To that end, we devised the ‘CLL-map’ project - an international endeavor to harmonize and analyze genomic, transcriptomic, and epigenomic data from 1148 patients.
The large genomic cohort, which was two-fold larger than previous studies, facilitated novel discovery. With greater statistical power, we identified 202 candidate genetic drivers of CLL (109 novel) and refined the characterization of the two IGHV subtypes, which revealed distinct genomic landscapes and predictors of patient outcome. Using 600 CLL RNA-seqs, we discovered 8 new gene expression subtypes that proved to be independent prognostic factors. Through CLL drug-screens and a machine learning classifier, we show the expression subtypes’ potential in precision medicine. Integrative multiomic analysis shows that clinical outcomes are associated with a combination of genetic, epigenetic, and gene expression features, further advancing our prognostic paradigm for CLL.
Overall, this work reveals fresh insights into CLL oncogenesis and prognostication and advances us towards improved precision medicine for CLL patients. In the current post-TCGA project era, our findings motivate the initiation of cancer multiomics projects at larger scale for additional tumor types.