Molecular pathogenesis of chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is characterised by the clonal expansion of mature, CD5 positive, B lymphocytes in the blood, marrow, lymph nodes and spleen. For the majority of patients, CLL follows an indolent clinical course, while a proportion of patients experience rapid disease progression. Despite the strong correlation between certain genetic defects and prognosis, there remains no single unifying pathogenic lesion in CLL. With recent advances in therapy it is increasingly important to stratify CLL patients according to risk. This has been highlighted by two recent studies, the first showing that immunoglobulin heavy chain mutational status predicts a durable response to frontline chemoimmunotherapy and the second showing that complex karyotype is a stronger predictor of poor response to ibrutinib and venetoclax therapy than TP53 deletion. In this review we discuss the molecular features of CLL and how technological advances can identify patient subsets and stratify them according to risk.