Sequencing of chronic lymphocytic leukemia therapies.

It is an unprecedented time for the treatment of patients with chronic lymphocytic leukemia (CLL) with the recent approval of several targeted agents for use in frontline, relapsed, refractory, and high-risk disease. Traditionally, frontline management of CLL has been a combination of chemotherapy (fludarabine, cyclophosphamide, bendamustine, or chlorambucil) with an anti-CD20 monoclonal antibody (rituximab, ofatumumab, obinutuzumab). The current landscape is rapidly evolving with the advent of therapies that demonstrate selective inhibition of important pathways necessary for CLL proliferation and survival. Despite considerable progress, much is still unknown and optimal treatment selection and sequence is still debatable. None of the new agents have been compared against each other and the impact of adding an additional agent to monotherapy is not yet fully elucidated. In routine clinical practice, the choice of therapy is based on nonrandomized comparisons, presence of comorbidities, and toxicity considerations. These recently approved drugs (ibrutinib, idelalisib, and venetoclax) are reporting excellent outcomes, including patients with high-risk disease such as 17p deletion (17p-) or TP53 mutations (TP53mut). Ibrutinib and venetoclax have been approved for use in 17p- patients (frontline and relapsed, respectively). Ibrutinib is currently moving into the frontline space given recent regulatory approvals. This review will summarize and interpret the limited therapeutic sequencing data available, highlighting the need for additional studies to optimize combination strategies and treatments after failure or discontinuation of these novel agents.