Risk-stratification in frontline CLL therapy: standard of care

The treatment of chronic lymphocytic leukemia (CLL) has been transformed over the past decade based on a better understanding of disease biology, especially regarding molecular genetic drivers and relevant signaling pathways. Agents focusing on B-cell receptor (in particular Bruton tyrosine kinase [BTK]) and apoptosis (BCL2) targets have replaced chemoimmunotherapy (CIT) as the treatment standard. BTK and BCL2 inhibitor-based therapy has consistently shown prolonged progression-free survival and in some instances even increased overall survival against CIT in frontline phase 3 trials. This improvement is particularly pronounced in high-risk CLL subgroups defined by unmutated IGHV, deletion 17p (17p-), and/or the mutation of TP53, making CIT in these subgroups essentially obsolete. Despite remarkable advances, these markers also retain a differential prognostic and predictive impact in the context of targeted therapies, mandating risk-stratification in frontline management. Furthermore, BTK- and BCL2-targeting agents differ in their adverse event profiles, requiring adjustment of treatment choice based on patient characteristics such as coexisting conditions, comedications, and delivery-of-care aspects.